The present invention relates to a plating apparatus for plating a substrate such as a semiconductor wafer with copper.

In the production of a semiconductor device, a plating process is often performed for plating one surface of a semiconductor wafer (hereinafter referred to simply as "wafer") . Plating apparatuses for the plating of the wafer are required to perform complicated process steps and to provide a high-quality metal film (for example, having a highly uniform thickness) by the plating. Since the semiconductor wafer is formed with fine holes and grooves, it is necessary to fill the fine holes and grooves with copper by the plating.

An exemplary plating apparatus for the copper plating of the semiconductor wafer is disclosed in US Patent No. 6,261,433 B1.

However, none of the conventional plating apparatuses are satisfactory in the qualityof a film formed by the plating, operability, productivity and the like.

It is an object of the present invention to provide a plating apparatus which is capable of properly performing a plating process.

It is another object of the present invention to provide a plating apparatus which features easier operation.

It is further another object of the present invention to provide a plating apparatus which features higher productivity.

It is still another object of the present invention to provide a plating cup which ensures that a plating process can properly be performed.

It is further another object of the present invention to provide a cathode ring which ensures that a plating process can properly be performed.

A plating apparatus (10) according to the present invention comprises: a plating vessel (61a to 61d) having a cylindrical side wall (361) for containing a plating liquid; a substrate holding mechanism (74a to 74d) for generallyhorizontallyholdingagenerallyroundsubstrate (W) to be treated; a cathode ring (80) provided in the substrate holding mechanism and having substantially the same inner diameter as the plating vessel for sealing a peripheral edge portion of a lower surface of the substrate, the cathode ring having a cathode (83) to be brought into contact with the substrate held by the substrate holding mechanism; and a rotative driving mechanism (45) for rotating the substrate held by the substrate holding mechanism together with the cathode ring; wherein the plating vessel has an upper edge portion complementary in configuration to a portion of the cathode ring opposed to the plating vessel so that the lower surface of the substrate held by the substrate holding mechanism can approach the plating vessel so as to be substantially flush with an upper edge of the plating vessel without interference between the upper edge portion of the plating vessel and the cathode ring. The components represented by the parenthesized alphanumeric characters are equivalent to those to be described in the following embodiment. However, it should be understood that the present invention be not limited to the embodiment. This definition is also applied to the following description.

With this arrangement, the plating liquid is contained in the plating vessel, and the lower surface of the to-be-treated substrate can be brought into contact with the plating liquid with the substrate being generally horizontally held bythesubstrateholding mechanism. The substrate may have a diameter greater than the inner diameter of the cathode ring. In this case, the peripheral edge portion of the lower surface of the substrate can be sealed by the cathode ring. Since the inner diameter of the cathode ring is virtually equal to the inner diameter of the plating vessel, a surface area of the substrate exposed from the cathode ring has a round shape having a diameter virtually equal to the inner diameter of the plating vessel, and the exposed surface area of the substrate is brought into contact with the plating liquid in a plating process.

With the lower surface of the substrate kept in contact with the plating liquid, an electrolytic plating process can be performed on the lower surface of the substrate by electrically energizing the substrate via the cathode. At this time, the substrate can be moved relative to the plating liquid by rotating the substrate by means of the rotative driving mechanism, whereby the uniformity of the plating is improved.

The plating liquid may be supplied into the plating vessel, for example, via a pipe connected to the bottom of the plating vessel. In this case, the plating process can be performed, while the plating liquid is continuously supplied into the plating vessel to overflow from the upper edge of the plating vessel. Thus, the surface of the plating liquid is kept raised slightly from the edge of the plating vessel (e.g., by about 2.5 mm). Since the upper edge portion of the plating vessel is complementary in configuration to the portion (lower portion) of the cathode ring opposed to the plating vessel, the substrate held by the substrate holding mechanism can be brought into contact with the plating liquid raised from the edge of the plating vessel without interference between the upper edge portion of the plating vessel and the cathode ring.

Further, the lower surface of the substrate held by the substrate holding mechanism can be brought into substantially flush relation with the upper edge of the plating vessel, so that a distance between the lower surface of the substrate and the upper edge of the plating vessel can be reduced (e. g. , to 0.3 mm to 1. 0 mm) in the plating process. In this case, the plating liquid continuously supplied into the plating vessel flows in the form of a laminar flow along the lower surface of the substrate to the peripheral edge of the substrate in the vicinity of the lower surface of the substrate, and then flows out of the plating vessel through a gap defined between the upper edge of the plating vessel and the lower surface of the substrate.

Even if air bubbles are trapped between the substrate and the plating liquid, the air bubbles flow together with the plating liquid out of the plating vessel . The laminar flow of the plating liquid flowing along the lower surface of the substrate to the peripheral edge of the substrate and the absence of the air bubbles on the lower surface of the substrate make it possible to form a uniform film by the plating. That is, this plating apparatus can advantageously perform the plating process.

The inventive plating apparatus may further comprise a first adjustment mechanism (230, 231, 233, 235, 238A, 238B) for generally aligning the center axis of the plating vessel with the rotation axis of the cathode ring.

With this arrangement, the center axis of the plating vessel can virtually be aligned with the rotation axis of the cathode ring by the first adjustment mechanism. Where the rotation axis and center axis of the cathode ring coincide with each other, the interference between the plating vessel and the cathode ring can be prevented even if the cathode ring is slightly spaced from the upper edge of the plating vessel. This state is maintained even when the substrate is rotated by the rotative driving mechanism.

In the inventive plating apparatus, the upper edge of the plating vessel is present within substantially the same plane. The apparatus may further comprise a second adjustment mechanism (238A, 238B) for positioning the upper edge of the plating vessel within a generally horizontal plane.

With this arrangement, the upper edge of the plating vessel can be positioned within the generally horizontal plane by the second adjustment mechanism. Therefore, the substrate generally horizontally held by the substrate holding mechanism can be spaced a substantially constant distance from the upper edge of the plating vessel in adjacent relation. Thus, the substrate can circumferentiallybe spaced a sufficiently small distance from the upper edge of the plating vessel in non-contact adjacent relation.

With the upper edge of the plating vessel positioned within the generally horizontal plane, the plating liquid continuously supplied into the plating vessel from the pipe connected to the bottom of the plating vessel overflows circumferentially uniformly from the upper edge of the plating vessel. Thus, the exposed area of the lower surface of the substrate can entirely be brought into contact with the plating liquid.

The inventive plating apparatus may further comprise a retracting mechanism (222a, 44a) having a pivot shaft (223) generally horizontally disposed at a lower height than the bottom of the plating vessel and coupled to the substrate holding mechanism, the retracting mechanism (222a, 44a) being capable of pivoting the substrate holding mechanism about the pivot shaft to move the substrate holding mechanism between an upper position above the plating vessel and a retracted position apart from the upper position.

With this arrangement, the substrate holding mechanism can be located at the upper position above the plating vessel in the plating process, and retracted from the upper position to the retracted position in maintenance of the apparatus by the retracting mechanism.

The inventive plating apparatus may further comprise a cathode cleaning liquid supplying mechanism (81) for supplying a cathode cleaning liquid to the cathode of the cathode ring for cleaning the cathode in the plating process.

The cathode is generally prevented from contacting the plating liquid when the peripheral edge portion of the substrate kept in contact with the cathode is sealed by the cathode ring. Where the sealing by the cathode ring is insufficient, however, the plating liquid is likely to reach the cathode. Further, even if the sealing by the cathode ring is proper, the plating liquid remaining on the exposed surface of the substrate is likely to be sucked into the gap between the substrate and the cathode ring to contact the cathode when the cathode ring is disengaged from the substrate after the completion of the plating process.

With the aforesaid arrangement, the cathode cleaning liquid can be supplied to the cathode by the cathode cleaning liquid supplying mechanism to rinse away the plating liquid adhering on the cathode. Thus, the cathode can be kept clean to properly electrically energize the substrate for the electrolytic plating.

Another plating apparatus (10) according to the present invention comprises: a plating vessel (61a to 61d) for containing a plating liquid for performing a plating process on a substrate (W) to be treated; a substrate holding mechanism (74a to 74d) to be disposed above the plating vessel for generally horizontally holding the substrate to bring the substrate into contact with the plating liquid contained in the plating vessel; and a retractingmechanism (222a, 44a) havingapivotshaft (223) generally horizontally disposed at a lower height than the bottom of the plating vessel and coupled to the substrate holding mechanism, the retracting mechanism being capable of pivoting the substrate holding mechanism about the pivot shaft to move the substrate holding mechanism between an upper position above the plating vessel and a retracted position apart from the upper position.

According to the present invention, the substrate held by the substrate holding mechanism can be brought into contact with the plating liquid contained in the plating vessel for the plating thereof. Further, the substrate holding mechanism can be located at the upper position above the plating vessel in the plating process, and retracted from the upper position to the retracted position in maintenance of the apparatus by the retracting mechanism.

In the inventive plating apparatus, the plating vessel may have a cylindrical side wall (361), and the substrate holding mechanism may include a cathode ring (80) having substantially the same inner diameter as the plating vessel for sealing a peripheral edge portion of a lower surface of the to-be-treated substrate, the cathode ring being rotatable about a rotation axis thereof, the cathode ring including a cathode (83) to be brought into contact with the substrate held by the substrate holding mechanism. The plating apparatus may further comprise a first adjustment mechanism (230, 231, 233, 235, 238A, 238B) for aligning the center axis of the plating vessel with the rotation axis of the cathode ring.

With this arrangement, the peripheral edge portion of the lower surface of the substrate held by the substrate holding mechanism is covered with the cathode ring, and an inward round area of the lower surface of the substrate is exposed from the cathode ring. With the exposed area of the lower surface of the substrate kept in contact with the plating liquid contained in the plating vessel, the substrate is electrically energized by the cathode of the cathode ring for electrolytic plating.

Where the rotation axis and center axis of the cathode ring coincide with each other, the plating vessel and the cathode ring can be kept in circumferentially adjacent relation without interference therebetween by aligning the center axis of the plating vessel with the rotation axis of the cathode ring by the first adjustment mechanism.

In the inventive plating apparatus, the plating vessel has an upper edge present within substantially the same plane. The apparatus may further comprise a second adjustment mechanism (238A, 238B) for positioning the upper edge of the plating vessel within a generally horizontal plane.

With this arrangement, the upper edge of the plating vessel can be positioned within the generally horizontal plane by the second adjustment mechanism. Therefore, the substrate generally horizontally held by the substrate holding mechanism can be brought into non-contact adjacent relation to the upper edge of the plating vessel, whereby the surface area of the substrate exposed from the cathode ring can be brought into contact with the plating liquid contained (filled) in the plating vessel.

In the inventive plating apparatus, the plating vessel may have a cylindrical side wall (361), and the substrate holding mechanism may include a cathode ring (80) having substantially the same inner diameter as the plating vessel for sealing a peripheral edge portion of a lower surface of the to-be-treated substrate, the cathode ring being rotatable about a rotation axis thereof, the cathode ring including a cathode (83) to be brought into contact with the to-be-treated substrate. The apparatus may further comprise a cathode cleaning liquid supplying mechanism (81) for supplying a cathode cleaning liquid to the cathode for cleaning the cathode in the plating process.

With this arrangement, the electrolytic plating process can be performed on the substrate by electrically energizing the substrate by the cathode . The cathode ring generally prevents the cathode from contacting the plating liquid in the plating process. However, if the plating liquid happens to reach the cathode for some reason, the cathode can be cleaned by the cathode cleaning liquid supplying mechanism. Thus, the cathode can be kept clean, and properly brought into contact with the substrate for the electrolytic plating.

Further another plating apparatus (10) according to the present invention comprises: a plating vessel (61a to 61d) for containing a plating liquid; an anode (76) disposed in the plating vessel; a mesh member (49) of a resin disposed at a higher height than the anode in the plating vessel; and a substrate holding mechanism (74a to 74d) for holding a to-be-treated substrate (W) so as to locate the substrate at a plating position in contact with the plating liquid filled in the plating vessel, wherein a distance between the substrate located at the plating position and the mesh member is 0.5 mm to 30 mm.

According to the present invention, an electrolytic plating process can be performed on the substrate kept in contact with the plating liquid by electrically energizing the plating liquid through the anode. At this time, the mesh member is present between the anode and the substrate. Since the mesh member is composed of the resin, the electrical resistance of the plating liquid in a region between the anode and the substrate in the plating vessel is increased due to the presence of the mesh member.

Theplatingapparatusmayfurthercompriseacathode to be brought into contact with a peripheral edge portion of the substrate. In an electrical conduction path extending from the anode through the plating liquid to the cathode kept in contact with the peripheral edge portion of the substrate, a path passing through the center of the substrate has substantially the same electrical resistance as a path passing through the peripheral edge portion of the substrate but not through the center of the substrate. This is because the electrical resistance of the plating liquid contained in the plating vessel is increased by the mesh member and, hence, the electrical resistance between the center of the substrate and the peripheral edge portion of the substrate (cathode) is much smaller than the electrical resistance of the path extending from the anode to the substrate.

A film growth rate in the plating process is virtually proportional to the amperage of the electric current flowing across the interface between the substrate and the plating liquid. Where the path passing through the center of the substrate has substantially the same electrical resistance as the path passing through the peripheral edge portion of the substrate but not through the center of the substrate as described above, the electric current generally uniformly flows between the plating liquid and the substrate at different points on the substrate. Thus, the film growth rate in the plating process is generally uniform over the substrate. Therefore, the film formed by the plating has a generally uniform thickness.

The mesh member preferably covers almost the entire plating vessel as viewed in plan. Thus, the plating liquid in the plating vessel has a uniform electrical resistance as measured vertically at different points within a horizontal plane.

Where the plating liquid is supplied into the plating vessel through a pipe connected to the bottom of the plating vessel, the plating liquid flows upward from a lower side in the plating vessel. At this time, contaminants in the plating liquid can be removed by the mesh member. The plating liquid flowing upward from the lower side is rectified into a generally uniform upward flow by the mesh member.

The plating apparatus may further comprise a rotative driving mechanism for rotating the substrate held by the substrate holding mechanism. Since the substrate located at the plating position and the mesh member are spaced only 0.5 mm to 30 mm from each other in adjacent relation, the plating liquid is drawn by the substrate in a limited region when the substrate is rotated in contact with the plating liquid. This suppresses the eddy flow of the plating liquid which is unwanted for the plating. Thus, the film formed by the plating has a uniform thickness.

The distance between the substrate located at the plating position and the mesh member is preferably 0.5 mm to 20 mm.

The mesh member may include a plurality of mesh members which are vertically stacked one on another. The stacked mesh members have an increased total thickness as measured vertically. This enhances the effect of increasing the electrical resistance between the anode and the substrate, the effect of removing the contaminants and the effect of rectifying the plating liquid. The plating liquid flows in the form of a laminar flow along the lower surface of the substrate to the peripheral edge of the substrate in the vicinity of the lower surface of the substrate.

A plating cup (56a to 56d) according to the present invention comprises: a plating vessel (61a to 61d) for containing a plating liquid; a shower head (75) for diffusively introducing the plating liquid into the plating vessel from a plating liquid introduction port (54) provided in the bottom of the plating vessel; a mesh anode (76) disposed at a higher height than the shower head in the plating vessel; and a mesh member (49) of a resin disposed at a higher height than the anode in the plating vessel.

According to the present invention, the plating liquid can diffusively beintroducedin various directions (at various angles) into the plating vessel by the shower head. Since the plating liquid is introduced into the plating vessel from the plating liquid introduction port provided in the bottom of the plating vessel, the plating liquid flows upward from a lower side in the form of an upward flow in the plating vessel. Since the anode is of a mesh shaped, the plating liquid can pass upwardly through the anode.

The plating liquid flows further upward to pass upwardly through the meshmember disposed at a height higher than the anode. At this time, the plating liquid is rectified into a uniform upward flow.

With the use of the plating cup, a plating process can be performed on a to-be-treated substrate, while the plating liquid is introduced from the plating liquid introduction port to overflow from the upper edge of the plating vessel with the substrate kept in contact with the surface of the plating liquid. Since the plating liquid is supplied in the form of a uniform upward flow to the surface of the substrate, the substrate can uniformly be plated.

Contaminants in the plating liquid can be removed by the mesh member. Thanks to the aforesaid effects, the plating process can advantageously be performed with the use of the plating cup.

In the inventive plating cup, the mesh member may include a plurality of mesh members which are stacked one on another.

The stacked mesh members have an increased total thickness as measured vertically. This enhances the plating liquid rectifying effect and the contaminant removing effect.

Still another plating apparatus (10) according to the present invention comprises: a cathode (83) to be brought into contact with a substrate (W) to be treated; and a cathode cleaning liquid supplying mechanism (81) for supplying a cathode cleaning liquid to the cathode for cleaning the cathode.

According to the present invention, an electrolytic plating process can be performed on the substrate by electrically energizing the substrate by the cathode. If the cathode is contaminated with the plating liquid, the cathode can be cleaned by the cathode cleaning liquid supplying mechanism. Thus, the cathode can be kept clean, so that the electrolytic plating process can be performed with the cathode properly kept in contact with the substrate.

The inventive plating apparatus may further comprise a conductivity meter (212) disposed downstream of the cathode in a flow channel of the cathode cleaning liquid supplied by the cathode cleaning liquid supplying mechanism for measuring the electrical conductivity of the cathode cleaning liquid.

With this arrangement, the electrical conductivity of the cathode cleaning liquid flowing in the vicinity of the cathode can be measured by the conductivity meter, which is disposed downstream of the cathode in the cathode cleaning liquid flow channel.

The plating apparatus may generally be constructed so as not to permit the plating liquid to intrude into the cathode cleaning liquid flow channel. The plating process can be performed by supplying the cathode cleaning liquid to the cathode while measuring the electrical conductivity of the cathode cleaning liquid flowing in the vicinity of the cathode by means of the conductivity meter. The cathode cleaning liquid and the plating liquid differ in electrical conductivity. Therefore, if the plating liquid is mixed in the cathode cleaning liquid, the electrical conductivity of the cathode cleaning liquid measured by the conductivity meter is changed. This makes it possible to detect the intrusion of the plating liquid into the cathode cleaning liquid flow channel, thereby avoiding such an event that the plating process is continuously performed with the cathode left contaminated with the plating liquid.

The cathode cleaning liquid may be, for example, deionized water. In this case, the electrical conductivity measured by the conductivity meter is drastically increased by even a very small amount of the plating liquid mixed in the cathode cleaning liquid.

The inventive plating apparatus may further comprise a cathode cleaning liquid collection vessel (210) for collecting the cathode cleaning liquid supplied by the cathode cleaning liquid supplying mechanism.

With this arrangement, the cathode cleaning liquid can be collected separately from the plating liquid used in the plating vessel by providing the cathode cleaning liquid collection vessel dedicated to the collection of the cathode cleaning liquid.

Further another plating apparatus (10) according to the present invention is adapted to perform a plating process on a to-be-treated substrate (W) with the use of a plating liquid, and comprises: a liquid supplying mechanism (81) for supplying liquid to a restriction region (80f) where intrusion of the plating liquid is prevented in the plating apparatus, the restriction region having a liquid inlet and a liquid outlet; and a conductivity meter (212) for measuring the electrical conductivity of the liquid flowing out of the outlet of the restriction region.

The plating liquid may usually be prevented from intruding into the restriction region. According to the present invention, if the plating liquid happens to intrude into the restriction region for some reason, the plating liquid flows together with the liquid supplied by the liquid supplying mechanism to reach the conductivity meter. Where the liquid suppliedby the liquid supplying mechanism and the plating liquid differ in electrical conductivity, the intrusion of the plating liquid into the restriction region where the intrusion of the plating liquid is usually prevented can be detected on the basis of the electrical conductivity measured by the conductivity meter.

The restriction region may be the inside of a through-hole or a planar region having a surface on which the liquid flows.

In the inventive plating apparatus, the liquid supplying mechanism may be capable of supplying the liquid in the plating process.

With this arrangement, the intrusion of the plating liquid into the restriction region can be detected in the plating process. If the plating process cannot properly be performed when the plating liquid intrudes into the restriction region, the plating process can be interrupted.

The inventive plating apparatus may further comprise a liquid collection vessel (210) for collecting the liquid supplied by the liquid supplying mechanism.

With this arrangement, the liquid can be collected separately from the plating liquid by providing the liquid collection vessel dedicated to the collection of the liquid supplied by the liquid supplying mechanism.

Still another plating apparatus (10) according to the present invention comprises: a plating vessel (61a to 61d) for containing a plating liquid for performing a plating process on a substrate (W) to be treated; a cathode (83) to be brought into contact with the substrate in the plating process; a recovery vessel (62a to 62d) disposed around the plating vessel for recovering the plating liquid overflowing from the plating vessel; and a cathode cleaning liquid collection vessel (210) disposed around the recovery vessel for collecting a cathode cleaning liquid for cleaning the cathode.

According to the present invention, the plating process can be performed, while the plating liquid is supplied into the plating vessel to overflow from the plating vessel into the recovery vessel with the to-be-treated substrate kept in contact with the surface of the plating liquid filled in the plating vessel. In this case, the plating liquid is raised from the upper edge of the plating vessel, so that the to-be-treated substrate can easily be brought into contact with the surface of the plating liquid. An electrolytic plating process can be performed by electrically energizing the substrate with the substrate kept in contact with the cathode.

The cathode cleaning liquid used for the cleaning of the cathode can be collected separately from the plating liquid used in the plating vessel by the cathode cleaning liquid collection vessel provided separately from the recovery vessel. Thus, the cathode cleaning liquid can be prevented from being mixed in the plating liquid, so that the plating liquid is suitable for reuse. In this case, the plating process can be performed on the substrate, for example, while the plating liquid is circulated through the plating vessel and the recovery vessel.

The inventive plating apparatus may further comprise a conductivity meter (212) disposed downstream of the cathode in a flow channel of the cathode cleaning liquid used for the cleaning of the cathode for measuring the electrical conductivity of the cathode cleaning liquid.

With this arrangement, the electrical conductivity of the cathode cleaning liquid flowing in the vicinity of the cathode can be measured by the conductivity meter, which is disposed downstream of the cathode in the cathode cleaning liquid flow channel.

The plating apparatus may generally be constructed so as not to permit the plating liquid to intrude into the cathode cleaning liquid flow channel. Since the cathode is disposed in the cathode cleaning liquid flow channel, the plating liquid is usually kept out of contact with the cathode.

The plating process can be performed by supplying the cathode cleaning liquid to the cathode while measuring the electrical conductivity of the cathode cleaning liquid flowing in the vicinity of the cathode by means of the conductivity meter. The cathode cleaning liquid and the plating liquid differ in electrical conductivity. Therefore, if the plating liquid is mixed in the cathode cleaning liquid, the electrical conductivity of the cathode cleaning liquid measured by the conductivity meter is changed. This makes it possible to detect the intrusion of the plating liquid into the cathode cleaning liquid flow channel, thereby avoiding such an event that the plating process is continuously performed with the cathode left contaminated with the plating liquid.

The inventive plating apparatus may further comprise a cathode cleaning liquid supplying mechanism (81) for supplying the cathode cleaning liquid to the cathode for the cleaning of the cathode.

With this arrangement, the cathode cleaning liquid can automatically be supplied to the cathode by the cathode cleaning liquid supplying mechanism. This facilitates the operation of the plating apparatus.

Further another plating apparatus according to the present invention comprises: an anode (76) for electrically energizing a plating liquid; a cathode (83) for electrically energizing a substrate (W) to be treated; and a plating power source (82) for applying a voltage between the anode and the cathode; wherein an electrical conduction path between the anode and the plating power source and an electrical conduction path between the cathode and the plating power source are isolated from the ground.

According to the present invention, an electrolytic plating process can be performed on the to-be-treated substrate by applying the voltage between the anode and the cathode by the plating power source with the anode and the cathode kept in contact with the plating liquid and the substrate, respectively, and with the substrate kept in contact with the plating liquid. Thus, a target metal contained in the form of cations (e.g., copper ions) in the plating liquid can be deposited on the substrate.

Since the electrical conduction path between the anode and the plating power source and the electrical conduction path between the cathode and the plating power source are not connected to the ground, an electric current is prevented from flowing through unintended portions in the plating apparatus, and a noise is prevented from interfering with electric currents flowing between the anode and the plating power source and between the cathode and the plating power source.

The inventive plating apparatus may further comprise: a substrate holding mechanism (74a to 74d) for holding the to-be-treated substrate (W), the substrate holding mechanism including a rotary shaft (77); a rotative driving mechanism (45) for rotating the substrate held by the substrate holding mechanism about the rotary shaft; and an electrical conduction line (198) provided in the rotary shaft and rotatable together with the rotary shaft by a rotation force of the rotative driving mechanism, the electrical conduction line being electrically connected to the cathode and electrically isolated from the rotary shaft; wherein the cathode is provided in the substrate holding mechanism and adapted to be brought into contact with the substrate held by the substrate holding mechanism.

With this arrangement, the substrate can be moved relative to the plating liquid by rotating the substrate by the rotative driving mechanism while keeping the substrate held by the substrate holding mechanism in contact with the plating liquid. Thus, the substrate can uniformly be plated.

The rotary shaft may be composed of an electrically conductive material such as a metal. Since the electrical conduction line is electrically isolated from the rotary shaft, an electric current flowing through the electrical conduction line does not flow through the rotary shaft and other electrically conductive members contacting the rotary shaft even if the rotary shaft is electrically conductive. Further, no noise interferes with the electriccurrentflowingthroughtheelectricalconduction line via the rotary shaft. Therefore, a predetermined amperage of electric current is allowed to flow through the to-be-treated substrate via the cathode.

The inventive plating apparatus may further comprise: a cathode ring (80) provided with the cathode and adapted to be brought into contact with a peripheral edge portion of the to-be-treated substrate; a spin base (78) which supports the cathode ring; and an insulative member (78i) provided between the cathode ring and the spin base.

With this arrangement, the electrical conduction path between the cathode and the plating power source can be isolated from the spin base by the insulative member even if the spin base is composed of an electrically conductive member such as a metal. Therefore, the electriccurrentflowingthroughtheelectricalconduction path between the cathode and the plating power source does not flow through the spin base and other electrically conductive members contacting the spin base. Further, no noise interferes with the electric current flowing through the electrical conduction line between the cathode and the plating power source via the spin base. Therefore, a predetermined amperage of electric current is allowed to flow through the to-be-treated substrate via the cathode.

The inventive plating apparatus may further comprise a rotary connector (197) for electrically connecting the cathode and the plating power source via a liquid metal.

With this arrangement, the electrical connection between the plating power source on the side of a stationary system and the cathode can be maintained by the rotary connector, even if the cathode is rotated together with the substrate holding mechanism.

The liquid metal may be, for example, mercury (Hg) .

Still another plating apparatus (10) according to the present invention comprises: a substrate holding mechanism (74a to 74d) for holding a substrate (W) to be treated; a cathode (83) to be brought into contact with the substrate held by the substrate holding mechanism; a first rotary shaft (77) having a first electrical conduction line (198) electrically connected to the cathode, and coupled to the substrate holding mechanism; a rotative driving mechanism (45) for rotating the substrate held by the substrate holding mechanism about the first rotary shaft; a second rotary shaft (194) having a second electrical conduction line (194); a rotation force transmission mechanism (193, 195, 196) for transmitting a rotative driving force between the first rotary shaft and the second rotary shaft and establishing an electrical conduction path between the first and second electrical conduction lines; and a rotary connector (197) attached to one end of the second rotary shaft and electrically connected to the second electrical conduction line.

According to the present invention, an electrical conduction path is established as extending from the rotary connector to the cathode through the second electrical conduction line, the rotation force transmissionmechanism and the first electrical conduction line. Thus, an electrical conduction path can be established between the plating power source connected to the rotary connector on the side of a stationary system and the cathode.

The rotation speed of the second rotary shaft can be reduced as compared with the rotation speed of the first rotary shaft by the rotation force transmission mechanism. Thus, the rotary connector can be rotated at a lower rotation speed for reduction of a load exerted on the rotary connector, whereby the service life of the rotary connector can be extended. The rotative driving mechanism may be coupled to the first rotary shaft or to the second rotary shaft.

The rotary connectormaybe of a slidable type (e.g. , a slip ring), but is preferably of a non-slidable type. Where the rotary connector is of a non-slidable type, a noise is less likely to interfere with an electric current flowing between the plating power source connected to the rotary connector on the side of the stationary system and the cathode.

The rotation force transmission mechanism may comprise: a first pulley attached to the first rotary shaft and at least partly electrically conductive; a second pulley attached to the second rotary shaft and at least partly electrically conductive; and a belt stretched between the first and second pulleys and at least partly electrically conductive.

Further another plating apparatus (10) according to the present invention comprises: a treatment fluid supplying member (203, 81b) having a fluid channel (81c) formed therein for supplying a treatment fluid to a substrate (W) to be treated; and a rotary joint (191) being disposed in the treatment fluid supplying member, and including a rotor (244), a stator (243) and a sliding portiondefinedbetween the rotor and the stator, the rotary joint having a main channel (270) to constitute a part of the fluid channel and a leak channel (271) branched from the main channel, the sliding portion being disposed in the leak channel.

According to the present invention, the treatment fluid can be supplied to the to-be-treated substrate from a treatment fluid supply source located on the side of a stationary system via the rotary joint even if the to-be-treated substrate is rotated together with a part of the treatment fluid supplying member. Since the main channel of the rotary joint constitutes a part of the fluid channel, the treatment fluid flows through the main channel.

At this time, the internal pressure of the leak channel is reduced as compared with the internal pressure of the main channel, whereby a part of the treatment fluid flowing through the main channel flows into the leak channel. Since the sliding portion is disposed in the leak channel, particles generated around the sliding portion are expelled out of the rotary joint via the leak channel. Thus, the particles generated around the sliding portion are prevented from being supplied to the to-be-treated substrate.

The inventive plating apparatus may further comprise a substrate holding mechanism (74a to 74d) having a support shaft (81b) to be disposed generally vertically for holding the to-be-treated substrate, wherein the fluid channel is provided in the support shaft and the rotary joint is attached to one end of the support shaft.

With this arrangement, the to-be-treated substrate held by the substrate holding mechanism can be rotated by rotating the substrate holding mechanism about the support shaft disposed generally vertically. At this time, the treatment fluid can be supplied from the treatment liquid supply source located on the side of the stationary system to the fluid channel provided in the support shaft via the rotary joint attached to the one end (upper end) of the support shaft.

A cathode ring (80) according to the present invention has a cathode (83) to be brought into contact with a peripheral edge portion of a substrate (W) to be treated, and comprises: a first electrically conductive member (80c) provided in the cathode ring for electrically connecting to a plating power source (82); a second electrically conductive member (80d) provided in the cathode ring and electrically connected to the cathode; and a third electrically conductive member (80e) provided between the first electrically conductive member and the second electrically conductive member, the third electrically conductive member being resilient and kept in resilient contact with the first and second electrically conductive members for electrical connection between the first electrically conductive member and the second electrically conductive member.

According to the present invention, the electrical connection between the first electrically conductive member and the second electrically conductive member can be maintained by keeping the third electrically conductive member in resilient contact with the first and second electrically conductive members, even if the cathode ring is warped. Thus, an electric current is allowed to flow between the plating power source and the cathode. Therefore, the plating process can properly be performed on the substrate with the use of the cathode ring.

The third electrically conductive member may be, for example, a coil spring.

Another cathode ring (80) according to the present invention comprises: a ring-shaped support member (80b, 80u); a cathode (83) provided in the support member and adapted to be brought into contact with a peripheral edge portion of a substrate (W) to be treated; an electrically conductive member (80d, 80e, 80c) provided in the support member and establishing an electrical conduction path between the cathode and a plating power source (82); and a seal member (80r) provided between the support member and the electrically conductive member for providing a seal between the support member and the electrically conductive member for prevention of intrusion of a plating liquid into the support member.

According to the present invention, the electrical conduction path is established as extending from the plating power source to the cathode through the electrically conductive member. Thus, an electrolytic plating process can be performed on the substrate by electrically energizing the substrate in contact with the cathode by the plating power source.

Further, the seal member prevents the intrusion of the plating liquid into the support member to keep the inside of the support member clean.

Further another cathode ring (80) according to the present invention comprises: a cathode (83) to be brought into contact with a peripheral edge portion of a substrate (W) to be treated; and a positioning member (78j, 79j) for fixing the cathode ring in a predetermined position with respect to a spin base (78) which is adapted to rotate while supporting the cathode ring.

According to the present invention, the cathode ring can easily be fixed in the predetermined position with respect to the spin base by the positioning member. The predetermined position herein means a position at which the center axis of the cathode ring generally coincides with the rotation axis of the spin base. Thus, the cathode ring can properly be rotated together with the spin base.

Still another cathode ring (80) according to the present invention comprises: a cathode (83) to be brought into contact with a peripheral edge portion of a substrate (W) to be treated; and an abutment portion (80a) for holding the substrate in abutment against the substrate, the abutment portion being composed of a rigid material and having a sealing surface (80s) for sealing the peripheral edge portion of the substrate.

According to the present invention, an area of the substrate to be brought into contact with a plating liquid can be limited by sealing the peripheral edge portion of the substrate by the sealing surface.

Since the abutment portion is composed of the rigid material, the size of the abutment portion and its periphery can be reduced. That is, where the abutment portion is not composed of the rigid material, an abutment portion supporting member should be provided separately from the abutment portion as extending from a side opposite from the substrate, so that the size of the abutment portion and its periphery is increased thereby to reduce the area of the substrate to be brought into contact with the plating liquid. Further, when the substrate abutting against the abutment portion is kept in contact with the plating liquid which is filled in a plating vessel and overflows from the edge of the plating vessel, the plating liquid is liable to be stagnated by the abutment portion supporting member, leading to a problem of deterioration in the uniformity of the plating.

According to the present invention, there is no need to provide the abutment portion supporting member separately from the abutment portion, making it possible to overcome the aforesaid problem.

Examples of the rigid material include rigid vinyl chloride resins, rigid fluororesins and polyimide resins. The sealing surface is preferably a polished surface. Thus, the sealing surface can be brought into more intimate contact with the to-be-treated surface of the substrate.

Still another plating apparatus (10) according to the present invention is adapted to perform a plating process on a to-be-treated surface of a generally round semiconductor wafer (W) having a plurality of fine holes or grooves formed in the surface thereof and a barrier layer and a seed layer sequentially provided on the surface as covering the holes or grooves, and comprises: a cassette stage (16) for receiving thereon a cassette (C) capable of accommodating the semiconductor wafer to be treated, the cassette stage including a cassette guide (51) for limiting a cassette loading position on the cassette stage and a cassette detection sensor (52) for detecting the presence or absence of the cassette at a predetermined position on the cassette stage; a plurality of plating units (20a to 20d) each including a cathode ring (80) having a cathode (83) to be brought into contact with the semiconductor wafer and rotatable together with the semiconductor wafer kept in contact with the cathode, and a plating vessel (61a to 61d) capable of containing a plating liquid and having an anode (76) disposed therein; a plurality of cleaning units (22a, 22b) each including a cup (101) having a drain port (105a) and adapted to clean the semiconductor wafer therein, a wafer holding member (102) for holding the semiconductor wafer in the cup, a wafer rotating mechanism (103) for rotating the semiconductor wafer held by the wafer holding member, and a cleaning liquid supply nozzle (102d, 107) for supplying a cleaning liquid including a post-treatment agent to the surface of the semiconductor wafer held by the wafer holding member, the cup being connected to an air exhaustion mechanism for exhausting air from the cup; a wafer transport mechanism (TR) for transporting the semiconductor wafer subjected to the plating process in any of the plating units to any of the cleaning units, the wafer transport mechanism including an extendible arm (41, 42) capable of generally horizontally holding the semiconductor wafer, a vertical movement mechanism (24) for moving up and down the arm, and a horizontal rotating mechanism (25) for rotating the semiconductor wafer held by the arm within a generally horizontal plane; a post-treatment agent supplying section (4) including a post-treatment agent tank (290) which contains the post-treatment agent to be used in the cleaning units, a tank enclosure (291) which houses therein the post-treatment agent tank, and a vat (292) for receiving therein the post-treatment agent which leaks out of the post-treatment agent tank, the tank enclosure being connected to an air outlet pipe (297) for exhausting air from the tank enclosure; a minor constituent analyzing section (3) including an analyzing cup (336) for containing the plating liquid for analyzing a specific minor constituent of the plating liquid to be used in the plating units, and a rotary platinum electrode (308) disposed in the analyzing cup; an enclosure (30) which houses therein a wafer treating section (12) including the plating units, the cleaning units and the wafer transport mechanism, the enclosure including a barrier wall for isolating the inside thereof from an external environment, a frame (37) which supports the wafer treating section, and a filter (31) provided in an upper portion thereof, the enclosure having a loading/unloading port (Wh) for loading and unloading the semiconductor wafer or the cassette capable of accommodating the semiconductor wafer, a deionized water pipe introduction port (32h) through which a deionized water pipe (32) is introduced into the enclosure, a compressed air pipe introduction port (33h) through which a compressed air pipe (33) is introduced into the enclosure, an air outlet opening provided in the bottom of the enclosure for exhausting air from the enclosure, and an air outlet pipe connection port (34h, 35h) connected to an air outlet pipe (34, 35) for exhausting air from the enclosure, the enclosure being constructed so that air introduced into the enclosure through the filter is exhausted from the enclosure through the air outlet opening and the air outlet pipe connected to the air outlet pipe connection port; and a system controller (155) for controlling the entire plating apparatus, the system controller including a plurality of printed circuit boards (155P), a central processing unit (155C), a storage device (155M) having a semiconductor storage medium and a magnetic storage medium and storing therein a plating apparatus control program at least partly described in a high-level language, a serial port (280, 281), a keyboard (157) having alphabet inputting keys and numeral inputting keys, and a display (156).

According to the present invention, the plating process and the cleaning process can be performed by the plating units and the cleaning units, respectively, in the single plating apparatus.

The cassette placed on the cassette stage can accommodate an untreated semiconductor wafer (hereinafter referred to simply as "wafer") as well as a wafer subjected to the plating process and the cleaning process.

The cassette can easily be placed in the predetermined position on the cassette stage by the cassette guide. Thus, the arm of the wafer transport mechanism can access the cassette placed on the cassette stage on the basis of cassette position information preliminarily stored in the storage device of the system controller for loading/unloading of the wafer. Since the presence or absence of the cassette on the cassette stage can be detected by the cassette detection sensor, it is possible to avoid such an event that the arm of the wafer transport mechanism accesses the cassette stage on the assumption that the cassette is placed on the cassette stage on which actually no cassette is placed.

In the plating unit, the wafer kept in contact with the cathode is brought into contact with the plating liquid contained in the plating cup, and the cathode and the anode are electrically energized, whereby a metal film (e.g., a copper film) can be formed on the wafer by electrolytic plating.

In the cleaning unit, contaminants adhering on the surface of the wafer can be removed, for example, by the post-treatment agent for cleaning the wafer. At this time, the wafer canuniformlybe cleaned by supplying the cleaning liquid toward the wafer from the cleaning liquid supply nozzle while rotating the wafer held by the wafer holding member by means of the wafer rotating mechanism. Mist of the cleaning liquid and the like generated during the cleaning of the wafer can be expelled out of the plating apparatus by the air exhaustion mechanism connected to the cup.

The cleaning liquid may include deionized water besides the post-treatment agent. In this case, the cleaning liquid supply nozzle may include a post-treatment agent supply nozzle and a deionized water supply nozzle.

The wafer transport mechanism is capable of transporting the wafer from the plating unit to the cleaning unit, so that the plating process and the cleaning process can successively be performed on the wafer. The wafer transport mechanism may be capable of transporting the wafer between the cassette placed on the cassette stage and the plating unit or the cleaning unit. In this case, the untreated wafer can be transported from the cassette, for example, to the plating unit and to the cleaning unit in sequence by the wafer transport mechanism so as to be automatically subjected to the plating process and the cleaning process in sequence and then accommodated again in the cassette under the control of the system controller.

When only a small amount of the post-treatment agent remains in the post-treatment agent tank in the post-treatment agent supplying section, the post-treatment agent tank may be replaced with another post-treatment agent tank containing a sufficient amount of the post-treatment agent. Since the post-treatment agent tank is housed in the tank enclosure, the post-treatment agent is unlikely to be scattered out of the tank enclosure even if the post-treatment agent is splashed during the replacement of the post-treatment agent tank. Further, the air outlet pipe is connected to the tank enclosure, so that vapor or mist of the post-treatment agent generated in the tank enclosure can be expelled out of the plating apparatus.

The volume of the vat is preferably equal to or greater than the volume of the post-treatment agent tank (where a plurality of post-treatment agent tanks are provided, the total volume of the plurality of post-treatment agent tanks). Even if the post-treatment agent entirely leaks out of the post-treatment tank, the post-treatment agent can be received in the vat.

In the minor constituent analyzing section, a CVS (cyclic voltammetric stripping) analysis or a CPVS (cyclic pulse voltammetric stripping) analysis can be performed on the plating liquid contained in the analyzing cup with the use of the rotary platinum electrode. Where the plating liquid contains a plating accelerating additive (hereinafter referred to simply as "accelerator") and a plating retarding additive (hereinafter referred to simply as "retarder") as minor constituents thereof, the accelerator and the retarder can quantitatively be analyzed through the CVS analysis or the CPVS analysis.

Where the concentration of the accelerator or the retarder is lower than a lower limit of a predetermined concentration range as the result of the analysis, a replenishment liquid containing the accelerator or the retarder is added in a proper amount to the plating liquid so as to adjust the concentration of the accelerator or the retarder in the predetermined concentration range. Thus, the plating process can properly be performed on the wafer with the use of the plating liquid having a properly adjusted accelerator or retarder concentration.

Since the wafer treating section is housed in the enclosure, the plating process, the cleaning process and a like process can be performed in a clean atmosphere isolated from the external environment. By exhausting air from the enclosure through the air outlet pipe, the internal pressure of the enclosure can be reduced to a negative pressure, and external air from which contaminants are removed by the filter can be introduced into the enclosure.

The external air may be forced into the enclosure through the filter by fans and let out from the air outlet opening. Thus, down-flow of clean air occurs in the enclosure.

Deionized water can be supplied into the wafer treating section through the deionized water pipe introduced into the enclosure through the deionized water pipe introduction port provided in the enclosure. The deionized water may be used, for example, for the cleaning process in the cleaning units. Some of driving mechanisms employed in the plating units and the cleaning units may pneumatically be driven. Compressed air for driving these driving mechanisms can be supplied to the driving mechanisms through the compressed air pipe introduced into the enclosure through the compressed air pipe introduction port provided in the enclosure.

The operation of the plating apparatus can be controlled on the basis of the plating apparatus control program stored in the storage device of the system controller, for example, to automatically sequentially perform the plating process and the cleaning process on the untreated wafer. The display may be capable of displaying the status of the plating apparatus (wafer treating status) . The keyboard may permit the operator to input wafer treating conditions and the like. Thus, the plating apparatus ensures easy operation and high productivity.

In the inventive plating apparatus, the plating vessel may have an upper edge portion complementary in configuration to a portion of the cathode ring opposed to the plating vessel, so that a lower surface of the to-be-treated semiconductor wafer kept in contact with the cathode can approach the plating vessel so as to be substantially flush with the upper edge of the plating vessel without interference between the upper edge portion of the plating vessel and the cathode ring.

With this arrangement, the wafer kept in contact with the cathode can be brought into contact with the plating liquid filled in the plating vessel and raised from the edge of the plating vessel without interference between the upper edge portion of the plating vessel and the cathode ring, because the upper edge portion of the plating vessel is complementary in configuration to the portion (lower portion) of the cathode ring opposed to the plating vessel.

Since the lower surface of the wafer kept in contact with the cathode can be brought into substantially flush relation with the upper edge of the plating vessel, a distance between the lower surface of the wafer and the upper edge of the plating vessel can be reduced (e.g., to 0 . 3 mm to 1. 0 mm) in the plating process. In this case, the plating liquid continuously supplied into the plating vessel flows in the form of a laminar flow along the lower surface of the wafer to the peripheral edge of the wafer in the vicinity of the lower surface of the wafer, and then flows out of the plating vessel from a gap defined between the upper edge of the plating vessel and the lower surface of the wafer.

Even if air bubbles are trapped between the wafer and the plating liquid, the air bubbles flow together with the plating liquid out of the plating vessel. The laminar flow of the plating liquid flowing along the lower surface of the wafer to the peripheral edge of the wafer and the absence of the air bubbles on the lower surface of the wafer make it possible to uniformly form a film by the plating.

The inventive plating apparatus may further comprise: a wafer holding mechanism (74a to 74d) to be disposed above the plating vessel for holding the to-be-treated semiconductor wafer to bring the semiconductor wafer into contact with the plating liquid contained in the plating vessel; and a retracting mechanism (222a, 44a) having a pivot shaft (223) generally horizontally disposed at a lower height than the bottom of the plating vessel and coupled to the wafer holding mechanism, the retracting mechanism being capable of pivoting the wafer holding mechanism about the pivot shaft to move the wafer holding mechanism between an upper position above the plating vessel and a retracted position apart from the upper position.

With this arrangement, the wafer holding mechanism can be located at the upper position above the plating vessel in the plating process and retracted from the upper position to the retracted position in maintenance of the apparatus by the retracting mechanism.

The cathode ring may constitute a part of the wafer holding mechanism.

The inventive plating apparatus may further comprise: a mesh member (49) of a resin disposed at a higher height than the anode in the plating vessel; and a wafer holding mechanism (74a to 74d) for holding the to-be-treated semiconductor wafer to locate the semiconductor wafer at a plating position at which the semiconductor wafer is kept in contact with the plating liquid filled in the plating vessel; wherein a distance between the semiconductor wafer located at the plating position and the mesh member is 0.5 mm to 30 mm.

With this arrangement, the mesh member is present between the anode and the wafer held by the wafer holding mechanism in the plating process, so that the electrical resistance between the anode and the wafer is greater than the electrical resistance of the to-be-treated surface of the wafer. Thus, an electric current uniformly flows across an interface between the wafer and the plating liquid at different points on the wafer. Therefore, the film formed by the plating has a substantially uniform thickness.

Where the plating liquid can be introduced into the plating vessel through a pipe connected to the bottom of the plating vessel, the plating liquid flows upward from a lower side in the plating vessel. At this time, contaminants in the plating liquid can be removed by the mesh member. Further, the plating liquid flowing upward from the lower side of the plating vessel is rectified into a virtually uniform upward flow by the mesh member.

Since the wafer located at the plating position and the mesh member are spaced only 0.5 mm to 30 mm from each other in adjacent relation, the plating liquid is drawn by the wafer in a narrowly limited region when the wafer is rotated in contact with the plating liquid. This suppresses the eddy flow of the plating liquid which is unwanted for the plating. Thus, the film formed by the plating has a uniform thickness.

The inventive plating apparatus may further comprise: a shower head (75) for diffusively introducing the plating liquid into the plating vessel from a plating liquid introduction port (54) provided in the bottom of the plating vessel; and a mesh member (49) of a resin disposed at a higher height than the shower head in the plating vessel; wherein the anode has a mesh shape and is located at a height between the shower head and the mesh member.

With this arrangement, the plating liquid can diffusively be introduced in various directions (at various angles) into the plating vessel by the shower head. The plating liquid is introduced into the plating vessel from the plating liquid introduction port provided in the bottom of the plating vessel, so that the plating liquid flows upward from a lower side in the form of an upward flow in the plating vessel. Since the anode is of a mesh shape, the plating liquid can pass upwardly through the anode.

The plating liquid flows further upward to pass upwardly through the mesh member disposed at a higher height than the anode. At this time, the plating liquid is rectified into a uniform upward flow. Therefore, the uniformity of the film formed by the plating can be improved by keeping the wafer in contact with the rectified plating liquid in the plating process.

The inventive plating apparatus may further comprise a cathode cleaning liquid supplying mechanism (81) for supplying a cathode cleaning liquid to the cathode for cleaning the cathode in the plating process.

With this arrangement, the cathode cleaning liquid can be supplied to the cathode for the cleaning of the cathode, so that the plating process can be performed with the cathode kept clean.

The inventive plating apparatus may further comprise: a liquid supplying mechanism (81) for supplying liquid to a restriction region (80f) where intrusion of the plating liquid is prevented in the plating apparatus, the restriction region having a liquid inlet and a liquid outlet; and a conductivity meter (212) for measuring the electrical conductivity of the liquid flowing out of the outlet of the restriction region.

The plating liquid may usually be prevented from intruding into the restriction region. With this arrangement, if the plating liquid happens to intrude into the restriction region for some reason, the plating liquid flows together with the liquid supplied by the liquid supplying mechanism to reach the conductivity meter. Where the liquid supplied by the liquid supplying mechanism and the plating liquid differ in electrical conductivity, the intrusion of the plating liquid into the restriction region where the intrusion of the plating liquid is usually prevented can be detected on the basis of the electrical conductivity measured by the conductivity meter.

The restriction region may be a region of the cathode ring where the intrusion of the plating liquid is prevented. Alternatively, the restriction region may be the inside of a through-hole having an outlet and an inlet or a planar region having a surface on which the liquid flows.

The inventive plating apparatus may further comprise: a recovery vessel (62a to 62d) disposed around the plating vessel for recovering the plating liquid overflowing from the plating vessel; and a cathode cleaning liquid collection vessel (210) disposed around the recovery vessel for collecting the cathode cleaning liquid used for cleaning the cathode kept in contact with the to-be-treated semiconductor wafer in the plating process .

With this arrangement, the plating liquid and the cathode cleaning liquid can separately be collected by the recovery vessel and the cathode cleaning liquid collection vessel.

The inventive plating apparatus may further comprise a plating power source (82) for applying a voltage between the anode and the cathode, wherein an electrical conduction path between the anode and the plating power source and an electrical conduction path between the cathode and the plating power source are isolated from the ground.

With this arrangement, the electrical conduction path between the anode and the plating power source and the electrical conduction path between the cathode and the plating power source are not connected to the ground, whereby an electric current is prevented from flowing through unintended portions in the plating apparatus, and a noise is prevented from interfering with electric currents flowing between the anode and the plating power source and between the cathode and the plating power source .

In the inventive plating apparatus, the plating units may each further comprise: a wafer holding mechanism (74a to 74d) for holding the to-be-treated semiconductor wafer; a first rotary shaft (77) having a first electrical conduction line (198) electrically connected to the cathode, and coupled to the wafer holding mechanism; a rotative driving mechanism (45) for rotating the semiconductor wafer held by the wafer holding mechanism about the first rotary shaft; a second rotary shaft (194) having a second electrical conduction line (194); a rotation force transmission mechanism (193, 195, 196) for transmitting a rotative driving force between the first rotary shaft and the second rotary shaft and establishing an electrical conduction path between the first and second electrical conduction lines; and a rotary connector (197) attached to one end of the second rotary shaft and electricallyconnectedtothesecondelectricalconduction line.

With this arrangement, an electrical conduction path is established as extending from the rotary connector to the cathode through the second electrical conduction line, the rotation force transmission mechanism and the first electrical conduction line. Thus, an electrical conduction path can be established between the plating power source connected to the rotary connector on the side of a stationary system and the cathode.

The rotation speed of the second rotary shaft can be reduced as compared with the rotation speed of the first rotary shaft by the rotation force transmission mechanism. Thus, the rotary connector can be rotated at a lower rotation speed for reduction of a load exerted on the rotary connector, whereby the service life of the rotary connector can be extended.

In the inventive plating apparatus, the plating units may each further comprise: a treatment fluid supplying member (203, 81b) having a fluid channel (81c) formed therein for supplying a treatment fluid to the to-be-treated wafer; and a rotary joint (191) being disposed in the treatment fluid supplying member, and including a rotor (244), a stator (243) and a sliding portion definedbetween the rotor and the stator, the rotary joint having a main channel (270) to constitute a part of the fluid channel and a leak channel (271) branched from the main channel, the sliding portion being disposed in the leak channel.

With this arrangement, the treatment fluid can be supplied to the to-be-treated wafer from a treatment fluid supply source located on the side of the stationary system via the rotary joint even if the to-be-treated wafer is rotated together with a part of the treatment fluid supplying member. Since the sliding portion is disposed in the leak channel, particles generated around the sliding portion can be expelled out of the rotary joint through the leak channel. Thus, the particles generated around the sliding portion are prevented from being supplied to the to-be-treated wafer.

In the inventive plating apparatus, the cathode ring may comprise : a first electrically conductive member (80c) provided in the cathode ring and electrically connected to a plating power source (82); a second electrically conductive member (80d) provided in the cathode ring and electrically connected to the cathode; and a third electricallyconductivemember (80e) provided between the first electrically conductive member and the second electrically conductive member, the third electrically conductive member being resilient and kept in resilient contact with the first and second electrically conductive members for electrical connection between the first electricallyconductivememberandthesecondelectrically conductive member.

With this arrangement, the electrical connection between the first electrically conductive member and the second electrically conductive member can be maintained by keeping the third electrically conductive member in resilient contact with the first and second electrically conductive members, even if the cathode ring is warped. Thus, an electric current is allowed to flow between the plating power source and the cathode.

In the inventive plating apparatus, the cathode may be adapted to be brought into contact with a peripheral edge portion of the semiconductor wafer, and the cathode ring may comprise: a ring-shaped support member (80b, 80u) which supports the cathode; an electrically conductive member (80d, 80e, 80c) provided in the support member and establishing an electrical conduction path between the cathode and a plating power source (82); and a seal member (80r) provided between the support member and the electrically conductive member for providing a seal for prevention of intrusion of the plating liquid into the support member.

With this arrangement, the electrical conduction path is established as extending from the plating power source to the cathode through the electrically conductive member. Thus, the electrolytic plating process can be performed on the wafer by electrically energizing the wafer kept in contact with the cathode by the plating power source.

Further, the seal member prevents the intrusion of the plating liquid into the support member to keep the inside of the support member clean.

In the inventive plating apparatus, the plating units may each further comprise a spin base (78) which supports the cathode ring, and the cathode ring may further comprise a positioning member (78j, 79j) for fixing the cathode ring in a predetermined position with respect to the spin base.

With this arrangement, the cathode ring can easily be fixed in the predetermined position with respect to the spin base by the positioning member. The predetermined position herein means a position at which the center axis of the cathode ring generally coincides with the rotation axis of the spin base. Thus, the cathode ring can properly be rotated together with the spin base.

In the inventive plating apparatus, the cathode may be adapted to be brought into contact with the peripheral edge portion of the semiconductor wafer, and the cathode ring may further comprise an abutment portion (80a) for holding the semiconductor wafer in abutment against the semiconductor wafer, the abutment portion being composed of a rigid material and having a sealing surface (80s) for sealing the peripheral edge portion of the semiconductor wafer.

With this arrangement, an area of the wafer to be brought into contact with the plating liquid can be limited by sealing the peripheral edge portion of the wafer by the sealing surface.

Since the abutment portion is composed of the rigid material, the size of the abutment portion and its periphery can be reduced.

The foregoing and other objects, features and effects of the present invention will become more apparent from the following description of the preferred embodiments with reference to the attached drawings.

• Fig. 1 is a block diagram illustrating the construction of a plating apparatus according to one embodiment of the present invention;
• Fig. 2 is a schematic plan view of a wafer treating section;
• Fig. 3 is a schematic perspective view illustrating the construction of an enclosure of the wafer treating section;
• Fig. 4 is a schematic sectional view illustrating a jack bolt and a frame attached to the enclosure;
• Fig. 5 (a) is a schematic plan view for explaining the construction of a robot body provided in the wafer treating section;
• Fig. 5(b) is a schematic side view for explaining the construction of the robot body provided in the wafer treating section;
• Fig. 5(c) is a schematic front view for explaining the construction of the robot body provided in the wafer treating section;
• Fig. 6(a) is a schematic plan view of a cassette stage on which a cassette is placed;
• Fig. 6 (b) is a schematic side view of the cassette stage on which the cassette is placed;
• Fig. 7 is a schematic front view illustrating the construction of a plating section;
• Fig. 8 is a diagram illustrating a relationship between the concentrations of copper in plating liquid samples and measured absorbances;
• Fig. 9 is a schematic sectional view illustrating the construction of a plating unit;
• Fig. 10 is a schematic sectional view illustrating a portion around a rotary pipe on a greater scale;
• Fig. 11 is a schematic sectional view of a rotary joint;
• Fig. 12 is a schematic sectional view illustrating a portion around a wafer as observed in a plating process;
• Fig. 13(a) is a schematic plan view illustrating the entire cathode ring (as viewed from the side of a spin base);
• Fig. 13(b) is a schematic sectional view illustrating the entire cathode ring;
• Fig. 13(c) is a schematic plan view illustrating an inner peripheral portion of the cathode ring on a greater scale;
• Fig. 14(a) is a schematic plan view illustrating the entire cathode;
• Fig. 14(b) is a schematic plan view illustrating a part of the cathode on a greater scale;
• Fig. 14(c) is a schematic sectional view illustrating a part of the cathode on a greater scale;
• Fig. 15 is a schematic diagram illustrating an electrical equivalent circuit in a plating vessel;
• Fig. 16 is a schematic plan view of a plating cup;
• Fig. 17 is a schematic sectional view illustrating a portion around a deionized water supply nozzle;
• Fig. 18 is a schematic sectional view illustrating a portion around a liquid trap;
• Fig. 19 is a schematic sectional view illustrating a portion around a junction between an air outlet pipe and a cathode cleaning liquid collection vessel;
• Fig. 20 is a schematic sectional view illustrating the plating unit with the spin base facing upward;
• Fig. 21 is a schematic side view of the plating unit;
• Fig. 22 is a schematic side view of the plating cup;
• Fig. 23 is a schematic sectional view illustrating the construction of a bevel etching unit;
• Fig. 24 is a schematic sectional view illustrating the construction of a cleaning unit;
• Fig. 25 is a block diagram illustrating the construction of a control system for the wafer treating section;
• Fig. 26 is a schematic diagram illustrating the construction of a major constituent managing section;
• Fig. 27 is a schematic diagram illustrating the construction of an analyzing cup provided in a minor constituent managing section;
• Fig. 28 is a schematic perspective view illustrating the construction of a post-treatment agent supplying section; and
• Fig. 29 is a block diagram illustrating the construction of control systems for the major constituent managing section, the minor constituent managing section and the post-treatment agent supplying section.

Fig. 1 is a block diagram illustrating the construction of a plating apparatus 10 according to one embodiment of the present invention.

The plating apparatus 10 includes a wafer treating section 1 for plating a surface of a semiconductor wafer (hereinafter referred to simply as "wafer") with the use of a plating liquid and etching (bevel-etching) a peripheral edge of the wafer after the plating, a major constituent managing section 2 having a copper supply source for supplying copper ions to the plating liquid for management of the concentrations of major constituents of the plating liquid, a minor constituent managing section 3 for managing minor constituents of the plating liquid, and a post-treatment agent supplying section 4 for supplying a post-treatment agent to the wafer treating section 1 for post-treatment of the wafer after the plating. The plating apparatus 10 is disposed in a clean room.

The plating liquid for use in the wafer treating section 1 contains sulfuric acid (supporting electrolyte), copper ions (target metal), iron (oxidizing/reducing agent) and water as major constituents thereof. The plating liquid further contains chlorine, a plating acceleratingadditive (brightener) andaplatingretarding additive (suppresser) as minor constituents thereof.

Two plating liquid transport pipes P12a, P12b extend between the wafer treating section 1 and the major constituent managing section 2 for transporting the plating liquid between these sections in opposite directions. Similarly, a sampling pipe 322 and a replenishment pipe 324 extend between the wafer treating section 1 and the minor constituent managing section 3 for transporting the plating liquid between these sections in opposite directions. Further, a post-treatment agent pipe P14 extends between the wafer treating section 1 and the post-treatment agent supplying section 4 for supplying the post-treatment agent from the post-treatment agent supplying section 4 to the wafer treating section 1.

The wafer treating section 1 includes a system controller for controlling the entire plating apparatus 10. The wafer treating section 1 is connected to the major constituent managing section 2, the minor constituent managing section 3 and the post-treatment agent supplying section 4 via signal lines L12, L13 and L14, respectively. The operations of the major constituent managing section 2, the minor constituent managing section 3 and the post-treatment agent supplying section 4 are controlled by the system controller provided in the wafer treating section 1.

The plating liquid being used in the wafer treating section 1 is transported (sampled) into the minor constituent managing section 3 through the sampling pipe 322. The minor constituent managing section 3 has an analyzing cup in which at least one of the minor constituents of the plating liquid transported from the wafer treating section 1 can be analyzed through a CVS (cyclic voltammetric stripping) analysis.

The minor constituent managing section 3 includes a minor constituent management controller, which is capable of calculating the amounts of the minor constituents to be added to the plating liquid in the wafer treating section 1 so as to adjust the concentrations of the minor constituents of the plating liquid on the basis of the results of the CVS analysis. Under the control of the minor constituent management controller, the minor constituents are supplied in the amounts thus calculated to the plating liquid in the wafer treating section 1 through the replenishment pipe 324.

The post-treatment agent supplying section 4 includes an agent tank containing the post-treatment agent, and an agent supply mechanism for supplying the post-treatment agent from the agent tank to the wafer treating section 1. Examples of the post-treatment agent include an etching liquid to be used for the bevel etching and a cleaning liquid.

Fig. 2 is a schematic plan view of the wafer treating section 1.

The wafer treating section 1 is adapted to perform a plating process for forming a thin copper film on the surface of the wafer W, then perform an etching process for etching the peripheral edge of the wafer W, and perform a cleaning process for cleaning the entire surfaces of the wafer W.

A wafer loading/unloading section 19 is disposed along a first transport path 14 extending linearly horizontally. In the wafer loading/unloading section 19, a plurality of cassette stages 16 (four cassette stages in this embodiment) which are each adapted to receive thereon one cassette C capable of accommodating a wafer W are arranged along the first transport path 14. The wafer W is of a generally round shape, and has a multiplicity of fine holes or grooves formed in the to-be-treated (to-be-plated) surface thereof and a barrier layer and a copper seed layer formed on the surface thereof.

A second linear transport path 15 is provided horizontally and perpendicularly to the first transport path 14. In this embodiment, the second transport path 15 extends from a middle portion of the first transport path 14. Aplating section 12 including four plating units 20a to 20d arranged along the second transport path 15 is provided on one side of the second transport path 15. The plating units 20a to 20d are each adapted to plate the surface of the wafer W with copper.

A post-treatment section 13 including two bevel etching units 21a, 21b and two cleaning units (spincleaning units) 22a, 22b arranged along the second transport path 15 is provided on the other side of the second transport path 15. The bevel etching units 21a, 21b are each adapted to etch the peripheral edge of the wafer W, while the cleaning units 22a, 22b are each adapted to clean opposite sides of the wafer W.

The first transport path 14 and the second transport path 15 constitute a T-shaped transport path, and a single transport robot TR is provided on the T-shaped transport path. The transport robot TR includes transport guide rails 17 disposed along the second transport path 15, and a robot body 18 movable along the transport guide rails 17. The operation of the transport robot TR is controlled by a transport controller 29.

The robot body 18 is capable of transporting the wafer W along the first transport path 14 and along the second transport path 15. Therefore, the robot body 18 can access any of the cassettes C placed on the cassette stages 16 to load and unload a wafer W, and access any of the plating units 20a to 20d, the bevel etching units 21a, 21b and the cleaning unit 22a, 22b to load and unload the wafer W.

A basic wafer transport route and a basic process sequence are as follows. First, an untreated wafer W is unloaded from one of the cassettes C, then transported to the front of one of the plating units 20a to 20d, and loaded into the plating unit 20a to 20d by the robot body 18 so as to be subjected to the plating process. In turn, the wafer W subjected to the plating process is unloaded from the plating unit 20a to 20d, and loaded into one of the bevel etching units 21a, 21b so as to be subjected to the bevel etching process.

Subsequently, the wafer W subjected to the bevel etching process is unloaded from the bevel etching unit 21a, 21b, then transported along the second transport path 15, and loaded into one of the cleaning units 22a, 22b by the robot body 18 so as to be subjected to the cleaning process.

Further, the wafer W subjected to the cleaning process is unloaded from the cleaning unit 22a, 22b and then transported along the second transport path 15 toward the first transport path 14 by the robot body 18. Upon reaching the first transport path 14, the robot body 18 starts moving along the first transport path 14 toward a cassette C placed on one of the cassette stages 16, and loads the wafer W on the cassette C.

Fig. 3 is a schematic perspective view illustrating the construction of an enclosure 30 of the wafer treating section 1.

The enclosure 30 has a generally rectangular box-like outer shape defined by a plurality of barrier walls (boundary walls) for isolating the inside thereof from the external environment. In the enclosure 30, partition walls are provided between the second transport path 15 and the plating section 12 and between the second transport path 15 and the post-treatment section 13. The space of the second transport path 15 is isolated from the space of the plating section 12 and from the space of the post-treatment section 13 by the partition walls, except when the wafer W is loaded and unloaded with respect to these sections.

A filter 31 for filtering off contaminants in air is provided in a top barrier wall of the enclosure 30. The filter 31 includes a first filter 31a disposed above the cassette stages 16, the first transport path 14 and the second transport path 15, and a second filter 31b disposed above the post-treatment section 13. Fans not shown are provided above the first filter 31a for forcibly introducing external air into the enclosure 30.

The cassette stage 16 is separated from the first transport path 14 by a barrier wall. This barrier wall has wafer loading/unloading ports Wh, through which the cassettes C placed on the cassette stages 16 are accessed from the first transport path 14 for the loading and unloading of the wafer W.

A plurality of slit-like openings 36 are provided in a portion of the enclosure 30 below the second transport path 15 as extending longitudinally of the second transport path 15. Since the space of the second transport path 15 is isolated by the enclosure 30 and the internal partitions, the space of the second transport path 15 is kept at a positive pressure when air is forcibly introduced into the enclosure 30 through the first filter 31a. Therefore, internal air is exhausted from the enclosure 30 through the openings 36. Thus, air flows from the upper side toward the lower side (the down-flow of air occurs) in the space of the second transport path 15.

Since no reagent is used in the space of the second transport path 15, the air flowing through this space is not contaminated. Therefore, the air flowing through the space of the second transport path 15 is exhausted through the openings 36 around the enclosure 30.

Air outlet ports 34h, 35h are respectively provided in a lower portion of a barrier wall defining the plating section 12 and a lower portion of a barrier wall defining the post-treatment section 13 on a side of the enclosure 30 opposite from the cassette stages 16. The air outlet port 34h is connected to one end of an air outlet duct 34, while the air outlet port 35h is connected to one end of an air outlet duct 35. The other ends of the air outlet ducts 34, 35 are connected to an in-plant exhauster system line. Thus, air possibly exposed to the plating liquid and the post-treatment agent in the plating section 12 and the post-treatment section 13 can forcibly be exhausted outside the clean room.

By forcibly exhausting the air from the post-treatment section 13 through the air outlet port 35h, the internal pressure of the post-treatment section 13 is kept at a negative pressure, so that external air is sucked into the post-treatment section 13 through the second filter 31b. Thus, air flows downward in the space of the post-treatment section 13.

A deionized water pipe introduction port 32h and a compressed air pipe introduction port 33h are provided in the vicinity of the air outlet port 35h in the barrier wall formed with the air outlet port 35h. A deionized water pipe 32 and a compressed air pipe 33 for supplying deionized water and compressed air for use in the wafer treating section 1 are introduced into the wafer treating section 1 through the deionized water pipe introduction port 32h and the compressed air introduction port 33h, respectively.

A frame 37 formedby combining iron structural parts is attached to a lower peripheral edge of the enclosure 30 to support the entire wafer treating section 1. A plurality of jack bolts 38 are attached to the frame 37 as properly spaced longitudinally of the structural parts of the frame 37. The frame 37 is supported by the jack bolts 38 so as to be spaced a predetermined distance from the floor of the clean room in which the wafer treating section 1 is disposed.

Fig. 4 is a schematic sectional view illustrating the jack bolt 38 and the frame 37.

The structural parts of the frame 37 each have a laterally open U-shaped cross section, and include two generally horizontal and parallel plate portions. Alower one of the plate portions serves as a support plate 37a which has an internal thread portion. The jack bolt 38 includes a bolt portion 38b having an external thread portion provided on its circumference, a generally round base disk 38a fixed generally perpendicularly to a lower end of the bolt portion 38b, and a lock nut 38c fitted around the bolt portion 38b.

The bolt portion 38b is engaged with the internal thread portion of the support plate 37a and extends generally vertically through the support plate 37a. The lock nut 38c is tightened toward the support plate 37a from the lower side of the support plate 37a. A distance between the base disk 38a and the support plate 37a, i.e., the height of the frame 37 from the floor of the clean room, is adjustable by variably positioning the support plate 37a with respect to the length of the bolt portion 38b.

For the adjustment of the height of the frame 37, the lock nut 38c is loosened (the lock nut 38c is rotated with respect to the bolt portion 38b so as to be moved apart from the support plate 37a), and then the base disk 38a is rotated in a proper direction. Thus, the bolt portion 38b is rotated together with the base disk 38a, so that the position of the support plate 37a with respect to the length of the bolt portion 38b is changed for the adjustment of the height of the frame 37 from the floor of the clean room. After the adjustment, the lock nut 38c is tightened toward the support plate 37a, whereby the bolt portion 38b is locked with respect to the support plate 37a.

The plurality of jack bolts 38 attached to the frame 37 have the same construction as shown in Fig. 4. Therefore, the leveling adjustment of the wafer treating section 1 can be achieved by attaching at least three jack bolts 38 to the frame 37 in a non-aligned manner and adjusting the positions of the support plates 37a with respect to the lengths of the bolt portions 38b.

Figs. 5(a), 5(b) and 5 (c) are a schematic plan view, a schematic side view and a schematic front view, respectively, for explaining the construction of the robot body 18.

The robot body 18 includes a base 23, a vertical articulated arm 24 attached to the base 23, a pivotal driving mechanism 25 attached to the vertical articulated arm 24, and a substrate holder 26 to be driven pivotally about a vertical pivot axis V0 by the pivotal driving mechanism 25 (only the substrate holder 26 is shown in Fig. 5(a)).

The substrate holder 26 includes a body 40 having a flat top, and a pair of retractable arms 41, 42 provided on the flat top of the body 40. A retractable driving mechanism (not shown) for horizontally advancing and retracting the pair of retractable arms 41, 42 is incorporated in the body 40.

The retractable arms 41 and 42 respectively include first arm portions 41a and 42a, second arm portions 41b and 42b, and substrate holder hands (effecters) 41c and 42c. The body 40 has a generally round shape as seen in plan, and the first arm portions 41a, 42a are attached to a peripheral edge portion of the body 40 pivotally about vertical pivot axes thereof. The first arm portions 41a, 42a are driven pivotally about the pivot axes by the retractable driving mechanism provided in the body 40.

The retractable arms 41, 42 each constitute a so-called scholar robot, which is operative so that the second arm portion 41b, 42b is pivoted about a vertical pivot axis thereof in synchronization with the pivoting of the first arm portion 41a, 42a. Thus, the first arm portion 41a, 42a and the second arm portion 41b, 42b of the retractable arm 41, 42 are stretched and unstretched so as to advance and retract the substrate holder hand 41c, 42c.

When the retractable arms 41, 42 are in an unstretched state, the substrate holder hands 41c, 42c are kept in vertically overlapped relation (Fig. 5(a)). Therefore, the substrate holder hand 41c of the retractable arm 41 has a bent shape for prevention of interference with the substrate holder hand 42c of the retractable arm 42 (Fig. 5(b)).

The vertical articulated arm 24 includes a first arm 24a and a second arm 24b. The first arm 24a is attached to the base 23 so that the first arm 24a is pivotal about a horizontal pivot axis H1 at one end thereof. The second arm 24b is attached to the other end of the first arm 24a pivotally about a horizontal pivot axis H2 at one end thereof. The pivotal driving mechanism 25 is attached to the other end of the second arm 24b pivotally about a horizontal pivot axis H3. The pivot axes H1, H2 and H3 are parallel to each other.

Amotor 27 for pivoting the first arm 24a is provided in the base 23, and a motor 28 for pivotally driving the second arm 24b is provided in a coupling between the first arm 24a and the second arm 24b. The motor 28 is rotatable in synchronization with the motor 27. A driving force transmission mechanism (not shown) for transmitting a driving force from the motor 28 to the pivotal driving mechanism 25 is incorporated in the second arm 24b. Thus, the pivotal driving mechanism 25 can constantly hold the substrate holder 26 in the same attitude (e.g., in such an attitude as to hold the wafer W horizontally), even if the first arm 24a and the second arm 24b are pivoted.

A motor (not shown) is incorporated in the pivotal driving mechanism 25. The pivotal driving mechanism 25 receives a driving force from this motor to pivotally drive the substrate holder 26 about the vertical pivot axis V0.

With this arrangement, the transport robot TR can move the substrate holder hands 41c, 42c horizontally and vertically within a range hatched in Fig. 5(c).

When the robot body 18 accesses the cassette C placed on the cassette stage 16 (see Fig. 2), the robot body 18 is moved to ends of the transport guide rails 17 on the side of the first transport path 14 by the transport controller 29. In this state, the substrate holder 26 is brought into opposed relation to the cassette C on the cassette stage 16 by the operation of the vertical articulated arm 24. That is, the substrate holder 26 can be moved along the first transport path 14, while the base 23 is kept located on the transport guide rails 17.

Then, the retractable arm 41, 42 is brought into opposed relation to the cassette C by the operation of the pivotal driving mechanism 25, and caused to access the cassette C by the retractable driving mechanism not shown for loading and unloading the wafer W with respect to the cassette C. When the wafer W is transferred between the cassette C and the retractable arm 41, 42, the substrate holder 26 is slightly moved up or down by the operation of the vertical articulated arm 24.

When the robot body 18 accesses any of the plating units 20a to 20d, the bevel etching units 21a, 21b and the cleaning units 22a, 22b (see Fig. 2), the robot body 18 is moved to the front of the corresponding unit on the transport guide rails 17 by a movement mechanism not shown. In this state, the substrate holder 26 is moved up or down to the height of a substrate loading/unloading port of the unit by the operation of the vertical articulated arm 24, and the retractable arm 41, 42 is brought into opposed relation to the unit by pivoting the substrate holder 26 by means of the pivotal driving mechanism 25.

In this state, the retractable arm 41, 42 is caused to access the unit by the retractable driving mechanism for the loading and unloading of the wafer W. When the wafer W is transferred between the unit and the retractable arm 41, 42, the substrate holder 26 is slightly moved up or down by the operation of the vertical articulated arm 24.

With this arrangement, the cassette C, the plating units 20a to 20d, the bevel etching units 21a, 21b and the cleaning units 22a, 22b can be accessed by the single robot body 18 for the loading and unloading of the wafer W.

The wafer W subjected to the plating process in the plating unit 20a to 20d (hereinafter referred to as "entire-surface-plated wafer") has a copper film formed on the entire surface thereof including the peripheral edge thereof by the plating, before the wafer W is subjected to the bevel etching process in the bevel etching unit 21a, 21b. Therefore, the substrate holder hand 41c, 42c which holds the entire-surface-plated wafer is contaminated with copper. Hence, it is preferred that one of the substrate holder hands 41c, 42c is dedicated to holding the entire-surface-plated wafer. Thus, the contamination with copper is prevented from spreading via the substrate holder hand 41c or 42c.

Figs. 6 (a) and 6(b) are a schematic plan view and a schematic side view, respectively, of the cassette stage 16 on which the cassette C is placed.

The cassette stage 16 includes a planar cassette base 50 for receiving thereon the cassette C. The cassette base 50 has a generally square shape as seen in plan. The cassette C has a generally square shape having a smaller size than the cassette base 50 as seen in plan, and has a wafer loading/unloading opening Ce provided on one lateral side thereof.

The cassette base 50 has cassette guides 51 provided on one surface (upper surface) thereof in association with four corners of the cassette C as seen in plan. Therefore, the cassette C can be located in position on the cassette base 50 with its corners in contact with the cassette guides 51. With the cassette C located in position on the cassette base 50, the wafer loading/unloading opening Ce faces toward the first transport path 14 (see Fig. 2).

A light emitting element 52a and a light receiving element 52b are respectively provided at generally middle points on opposite edges of the cassette base 50 (excluding an edge having the wafer loading/unloading opening Ce) on the surface of the cassette base 50. The light emitting element 52a and the light receiving element 52b constitute a transmissive photosensor 52. When no cassette C is present on the cassette base 50, light emitted from the light emitting element 52a is received by the light receiving element 52b. When the cassette C is present on the cassette base 50, the light emitted from the light emitting element 52a is blocked by the cassette C and does not reach the light receiving element 52b. Thus, a judgment can be made on the presence or absence of the cassette C on the cassette base 50.

Fig. 7 is a schematic front view illustrating the construction of the plating section 12.

The plating section 12 includes a plurality of plating units (the four plating units 20a to 20d in this embodiment) for the plating of the wafer W, and a plating liquid container 55 for containing the plating liquid. The plating units 20a to 20d respectively include plating cups 56a to 56d for containing the plating liquid, and wafer holding/rotating mechanisms (treatment heads) 74a to 74d to be located above the plating cups 56a to 56d.

The plating liquid container 55 is capable of containing the plating liquid in a much greater amount than the plating cups 56a to 56d (e.g., 20 times the total volume of the plating cups 56a to 56d). Since a great amount of the plating liquid can be stored in the plating liquid container 55, the total amount of the plating liquid to be used in the plating section 12 can be increased. Thus, variations in the composition of the plating liquid can be reduced during the plating process.

The plating liquid transport pipe P12a for transporting the plating liquid to the major constituent managing section 2 is connected to the bottom of the plating liquid container 55 in communication with the plating liquid container 55. The plating liquid transport pipe P12b for introducing the plating liquid transported from the major constituent managing section 2 into the plating liquid container 55, the sampling pipe 322 for transporting the plating liquid to the minor constituent managing section 3, and the replenishment pipe 324 for transporting the plating liquid between the minor constituent managing section 3 and the plating liquid container 55 in opposite directions are introduced into the plating liquid container 55 from the top of the plating liquid container 55. The plating liquid transport pipe P12b, the sampling pipe 322 and the replenishment pipe 324 extend to a depth at which open ends thereof are submerged in the plating liquid in the plating liquid container 55.

The plating cups 56a to 56d are located at a higher position than the plating liquid container 55. A liquid supply pipe 57 extends from the bottom of the plating liquid container 55, and is branched into four branch liquid supply pipes 58a to 58d. The branch liquid supply pipes 58a to 58d extend upward to be respectively connected to bottom center portions of the plating cups 56a to 56d in communication with the plating cups 56a to 56d.

Pumps P1 to P4, filters 59a to 59d and flow meters 60a to 60d are provided in this order from a lower side to an upper side in the respective branch liquid supply pipes 58a to 58d. The pumps P1 to P4 are respectively capable of pumping the plating liquid from the plating liquid container 55 to the plating cups 56a to 56d. The operations of the pumps P1 to P4 are controlled by the system controller 155. The filters 59a to 59d are capable of removing particles (contaminants) from the plating liquid. Signals indicative of the flow rates of the plating liquid is outputted from the flow meters 60a to 60d, and inputted to the system controller 155.

The plating cups 56a to 56d respectively include cylindrical plating vessels (liquid containing portions) 61a to 61d provided inwardly thereof, and recovery vessels 62a to 62d surrounding the plating vessels 61a to 61d. The branch liquid supply pipes 58a to 58d are connected in communication with the plating vessels 61a to 61d. Branch return pipes 63a to 63d extend from bottom portions of the recovery vessels 62a to 62d. The branch return pipes 63a to 63d are connected in communication with a return pipe 64, which extends into the plating liquid container 55.

With the aforesaid arrangement, the plating liquid is supplied, for example, to the plating vessel 61a from the plating liquid container 55 through the liquid supply pipe 57 and the branch liquid supply pipe 58a by operating the pump P1. The plating liquid overflows from the top of the plating vessel 61a, and is fed back into the plating liquid container 55 from the recovery vessel 62a through the branch return pipe 63a and the return pipe 64 by gravity. That is, the plating liquid is circulated through the plating liquid container 55 and the plating cup 56a.

Similarly, the plating liquid is circulated through the plating liquid container 55 and the plating cup 56b, 56c or 56d by operating the pump P2, P3 or P4. When the plating process is performed in any of the plating units 20a to 20d, the plating liquid is circulated through the plating cup 56a to 56d of the corresponding plating unit 20a to 20d and the plating liquid container 55. Thus, the plating liquid container 55 is shared by the four plating units 20a to 20d.

One end of a bypass pipe 65 is connected to the branch liquid supply pipe 58a between the pump P1 and the filter 59a. The other end of the bypass pipe 65 is introduced into the plating liquid container 55. Absorptiometers 66A, 66B for measuring absorbances of the plating liquid at specific wavelengths of light are provided in the bypass pipe 65. The absorptiometer 66A is provided for determining the concentration of copper in the plating liquid, while the absorptiometer 66B is provided for determining the concentration of iron in the plating liquid.

When the pump P1 is operated to circulate the plating liquid through the plating liquid container 55 and the plating cup 56a, a part of the plating liquid flowing through the branch liquid supply pipe 58a flows into the bypass pipe 65 due to a pressure loss by the filter 59a. That is, the plating liquid can be introduced into the bypass pipe 65 without provision of a dedicated pump in the bypass pipe 65.

The absorptiometers 66A, 66B each include a cell 67A, 67B composed of a transparent material, and a light emitting section 68A, 68B and a light receiving section 69A, 69B disposed in opposed relation with the cell 67A, 67B interposed therebetween. The light emitting sections 68A and 68B are respectively capable of emitting light beams having specific wavelengths corresponding to absorption spectra of copper and iron (e.g., 780 nm for copper). The light receiving sections 69A and 69B are respectively capable of measuring the intensities of the light beams emitted from the light emitting sections 68A and 68B and transmitted through the plating liquid in the cells 67A and 67B. The absorbances of the plating liquid are determined on the basis of the light intensities. Signals indicative of the absorbances are outputted from the absorptiometers 66A, 66B, and inputted to the system controller 155.

A temperature sensor 70 and an electromagnetic conductivity meter 71 are attached to a side wall of the plating liquid container 55. The temperature sensor 70 and the electromagnetic conductivity meter 71 are located at a height lower than the surface level of the plating liquid contained in the plating liquid container 55. Detectors of the temperature sensor 70 and the electromagnetic conductivity meter 71 project into the plating liquid container 55, and are respectively adapted to measure the temperature and electrical conductivity of the plating liquid. Output signals of the temperature sensor 70 and the electromagnetic conductivity meter 71 are inputted to the system controller 155.

The concentrations of copper and iron in the plating liquid can be determined by measuring the absorbances of the plating liquid at the specific wavelengths of light. An explanation will be given to how to determine the copper concentration on the basis of the absorbance of the plating liquid.

For the determination of the copper concentration of the plating liquid, a relationship between the copper concentration and the absorbance is preliminarily determined. First, plural plating liquid samples having different copper concentrations are prepared. Copper sulfate is added as a copper source for the preparation of the plating liquid samples . The plating liquid samples each have substantially the same composition as the plating liquid actually used for the plating process, except that the copper concentrations thereof are different. The absorbances of the plating liquid samples are measured by the absorptiometer 66A. Thus, therelationshipbetween the copper concentration and the absorbance (copper calibration line) is determined on the basis of the known copper concentrations and the measured absorbances of the plating liquid samples as shown in Fig. 8.

For the determination of an unknown copper concentration of the plating liquid, the absorbance of the plating liquid is measured by the absorptiometer 66A. Then, the copper concentration is determined on the basis of the measured absorbance and the copper calibration line.

Similarly, a relationship between the iron concentration and the absorbance (iron calibration line) is preliminarily determined on the basis of known iron concentrations and measured absorbances of plating liquid samples, and the concentration of iron in the plating liquid is determined on the basis of the absorbance of the plating liquid measured by the absorptiometer 66B and the iron calibration line.

The system controller 155 includes a storage device storing therein data of the copper calibration line and the iron calibration line. The system controller 155 is capable of determining the copper concentration on the basis of the output signal of the absorptiometer 66A and the data of the copper calibration line, and determining the iron concentration on the basis of the output signal of the absorptiometer 66B and the data of the iron calibration line.

An ultrasonic level meter 72 is provided above the plating liquid container 55. The ultrasonic level meter 72 is capable of detecting the surface level of the plating liquid in the plating liquid container 55. An output signal of the ultrasonic level meter 72 is inputted to the system controller 155. A capacitive level meter may be employed instead of the ultrasonic level meter 72.

The plating liquid container 55, the liquid supply pipe 57, the branch liquid supply pipes 58a to 58d, the branch return pipes 63a to 63d and the return pipe 64 are disposed in a pipe chamber 73 virtually air-tightly enclosed by the enclosure 30 and partition walls of the wafer treating section 1. The pipe chamber 73 has the air outlet port 34h, which is connected to the air outlet duct 34. The other end of the air outlet duct 34 is connected to the in-plant exhauster system line. The internal pressure of the pipe chamber 73 is reduced to a negative pressure by air exhaustion through the exhauster system line, so that air possibly exposed to the plating liquid and the like in the plating section 12 can forcibly be exhausted out of the clean room.

Fig. 9 is a schematic sectional view illustrating the common construction of the plating units 20a to 20d as observed in the plating process. The wafer holding/rotating mechanisms 74a to 74d are each supported by a column-shaped inversion base 181 extending generally horizontally. An inversion driving section 43 is connected to one end of the inversion base 181.

The inversion driving section 43 includes a column-shaped vertical base 182 extending vertically, a rotary actuator 183 attached to the vertical base 182 and having a rotation shaft perpendicular to the vertical base 182 and parallel to the inversion base 181, and a toothed pulley 184 attached to the rotation shaft of the rotary actuator 183, a toothed pulley 185 attached to a shaft extending parallel to the shaft of the rotary actuator 183 and supported rotatably by the vertical base 182, and a timing belt 186 stretched between the toothed pulley 184 and the toothed pulley 185 for transmitting a rotation force of the rotary actuator 183.

The rotary actuator 183 may be, for example, pneumatically driven. The inversion base 181 is attached to the vicinity of the shaft of the toothed pulley 185 perpendicularly to the toothed pulley 185. The inversion base 181 and the wafer holding/rotating mechanism 74a to 74d supported by the inversion base 181 can be pivoted (inverted) about the horizontal shaft as indicated by an arrow a in Fig. 9 by a pivotal driving force of the rotary actuator 183. Thus, the wafer W held by the wafer holding/rotating mechanism 74a to 74d can face upward or downward toward the plating cup 56a to 56d.

The vertical base 182 is coupled to a lift mechanism 44. The lift mechanism 44 includes a column-shaped guide 44a extending generally vertically, a support member 44b extending from the guide 44a perpendicularly to the length of the guide 44a, a first motor 44c attached to the support member 44b and having a rotation shaft extending generally vertically, and a ball thread 44d coaxially attached to the rotation shaft of the first motor 44c The first motor 44c is located below the ball thread 44d. The first motor 44c may be, for example, a servo motor.

A support member 182a having an internal thread portion is provided in threading engagement with the ball thread 44d in the vicinity of a lower end of the vertical base 182. The guide 44a vertically guides the vertical base 182 while preventing the vertical base 182 from rotating about the axis of the ball thread 44d.

With this arrangement, the vertical base 182 can be moved vertically by rotating the first motor 44c. Therefore, the inversion base 181 coupled to the vertical base 182 and the wafer holding/rotating mechanism 74a to 74d supported by the inversion base 181 can vertically be moved up and down (in directions indicated by arrowsb in Fig. 9).

The wafer holding/rotating mechanism 74a to 74d includes a rotary pipe 77 and a disk-shaped spin base 78 attached to one end of the rotary pipe 77 perpendicularly to the rotary pipe 77.

Fig. 10 is a schematic sectional view illustrating a portion around the rotary pipe 77 on a greater scale. Referring to Figs. 9 and 10, the rotary pipe 77 is supported rotatably about its axis by the inversion base 181 via a bearing 181b.

A plurality of wafer transfer pins 84 are provided on a surface of the spin base 78 opposite from the rotary pipe 77 between the center and the peripheral edge of the spin base 78. A plurality of support posts (e.g., four support posts) 79 are provided in a peripheral edge portion on the surface of the spin base 78 opposite from the rotary pipe 77. An annular cathode ring 80 is attached to distal ends of the support posts 79. The support posts 79 have a greater length than the wafer transfer pins 84.

The cathode ring 80 has an abutment portion 80a projecting toward the center of the cathode ring 80. The abutment portion 80a has an inner diameter slightly smaller than the diameter of the wafer W. The cathode ring 80 further has a projection 80p projecting opposite from the support posts 79.

A susceptor 81 is provided coaxially with the rotary pipe 77. The susceptor 81 includes a support shaft 81b extending through the rotary pipe 77, and a disk-shaped wafer back side press plate 81a attached to an end of the support shaft 81b (on the side of the cathode ring 80) perpendicularly to the support shaft 81b. The support shaft 81b is supported coaxially with the rotary pipe 77 by a ball spline 190, while being permitted to move axially of the rotary pipe 77.

The wafer back side press plate 81a is surrounded by the plurality of support posts 79. The wafer back side press plate 81a has a slightly smaller diameter than the wafer W. An end portion of the support shaft 81b opposite from the wafer back side press plate 81a projects out of the rotary pipe 77.

The susceptor 81 is coupled to a susceptor movement mechanism 46. The susceptor movement mechanism 46 includes an air cylinder 46a attached to the inversion base 181 and having a piston extending parallel to the support shaft 81b, and a transmission member 46b which couples the piston of the air cylinder 46a to the support shaft 81b. The transmission member 46b is fixed to the end portion of the support shaft 81b projecting out of the rotary pipe 77 opposite from the wafer back side press plate 81a. The susceptor 81 can be moved along the center axis of the rotary pipe 77 by driving the air cylinder 46a.

The wafer back side press plate 81a is formed with holes in association with the wafer transfer pins 84. Thus, the wafer transfer pins 84 are inserted into the holes of the wafer back side press plate 81a as the susceptor 81 is moved with respect to the rotary pipe 77. With the aforesaid arrangement, the wafer W can be held by the abutment portion 80a of the cathode ring 80 and the wafer back side press plate 81a.

A rotative driving mechanism 45 for rotating the rotary pipe 77 about its axis is coupled to the rotary pipe 77. The rotative driving mechanism 45 includes a second motor 45a provided on the inversion base 181 and having a rotation shaft parallel to the axis of the rotary pipe 77, a toothed pulley 45b fixed to the rotation shaft of the second motor 45a, a toothed pulley 45c provided around the rotary pipe 77, and a timing belt 45d stretched between the toothed pulley 45b and the toothed pulley 45c for transmitting a rotation force of the second motor 45a. The toothed pulleys 45b, 45c and the timing belt 45d are housed in a cover 181c (not shown in Fig. 9) attached to the inversion base 181.

The rotary pipe 77 can be rotated about its axis (in a direction indicated by an arrow c in Fig. 9) by a rotative driving force of the secondmotor 45a. The second motor 45a may be, for example, a servo motor. The rotation of the rotary pipe 77 is transmitted to the support shaft 81b through the ball spline 190, so that the rotary pipe 77 and the susceptor 81 are rotated together. Thus, the wafer W held by the abutment portion 80a of the cathode ring 80 and the wafer back side press plate 81a can be rotated.

In the plating process, the wafer holding/rotating mechanism 74a to 74d is moved down by the lift mechanism 44 with the wafer W thus held as facing downward, and a lower surface of the wafer W is brought into contact with the plating liquid filled in the plating vessel 61a to 61d.

A rotary joint 191 is attached to the end of the support shaft 81b opposite from the wafer back side press plate 81a. One end of a supply pipe 203 and one end of a leak pipe 204 are connected to the rotary joint 191. The other end of the supply pipe 203 is branched into a cathode cleaning liquid pipe 201 and a nitrogen gas pipe 202.

The cathode cleaning liquid pipe 201 is connected to a cathode cleaning liquid supply source, and the nitrogen gas pipe 202 is connected to a nitrogen gas supply source. A valve 201V is provided in the cathode cleaning liquid pipe 201, so that a cathode cleaning liquid can be supplied into the rotary joint 191 by opening the valve 201V. The cathode cleaning liquid may be, for example, deionized water. In this case, the cathode cleaning liquid (deionized water) can be supplied into the cathode cleaning liquid pipe 201 through the deionized water pipe 32 (see Fig. 3) which is introduced into the enclosure 30 through the deionized water supply pipe introduction port 32h of the enclosure 30.

A valve 202V is provided in the nitrogen gas pipe 202, so that nitrogen gas can be supplied into the rotary joint 191 by opening the valve 202V.

A single fluid channel 81c extends through the support shaft 81b along the center axis of the support shaft 81b. Aplurality of fluid channels 81d are provided in the wafer back side press plate 81a in communication with the fluid channel 81c as extending from the center to the peripheral edge of the wafer back side press plate 81a. The fluid channels 81d open in the peripheral edge of the wafer back side press plate 81a.

Even during the rotation of the susceptor 81, a tr