BACKGROUND OF THE INVENTION
1. FIELD OF THE INVENTION
The present invention relates to a processing apparatus
of an insulative substrate for use in a PDP (plasma display) manufacturing apparatus,
a master writer manufacturing apparatus for a DVD (digital video (or versatile)
disc), a substrate processing apparatus for a hard disc manufacturing apparatus,
a reticle fixing apparatus in an EB (electron beam) exposure apparatus, and a CVD,
etching or sputtering apparatus for manufacturing elements to be formed on SOS (silicon
on sapphire) and SOI (silicon on insulator) wafers.
2. DESCRIPTION OF PRIOR ART
In the manufacturing apparatuses for such as a DVD, a PDP
or the like, a material to be processed is a glass substrate which shows electrically
insulative characteristic. Therefore, in the conventional art, since it is impossible
to electrostatically attract these substrates within a vacuum, they are flatly placed
on a stage in the manufacturing apparatus thereof or they are fixed with a mechanical
mechanism.
A reticle of the EB exposure apparatus is comprised of
quartz which also shows electrically insulative characteristic. Therefore, conventionally,
the reticle is fixed tinder a vacuum with a mechanical mechanism.
SOS wafers and SOI wafers, attracting attention as next-generation
alternatives to silicon wafers, show electrically insulative characteristic with
regards to the surface by which they are mounted on a.stage. Therefore, conventionally,
it is impossible to apply a fixing method using an electrostatic chuck in the manufacturing
apparatus for forming devices on these wafers. A means and a principle of electrostatically
attracting a silicon wafer are disclosed, for example, in Japanese Patent Application
Laid-Open No. Hei
5-63062 (1993
), however it is impossible to electrostatically attract an insulative
substrate in accordance with the principle.
Also, there was known an apparatus for electrostatically
attracting a paper, for example, an electrostatic plotter.
As the level and integration is advanced in the process
for forming devices or the like on a substrate for use in a DVD, PDP, or a hard
disc, or on an SOS or SOI, the temperature control in the process comes to be very
important. With regards to the conventional process for forming devices on a silicon
wafer, the temperature control is conducted in the process using an electrostatic
chuck.
However, since the electrostatic chuck of the conventional
art can attract only a conductor or semiconductor, a material to be processed cannot
be electrostatically attracted in a case of having an electrically insulative characteristic.
Therefore, it is impossible to control the temperature in the process with high
accuracy.
Therefore, an electrostatic chuck, with which an insulative
substrate can be electrostatically attracted, and a processing apparatus using such
an electrostatic chuck are desired.
For fixing a reticle in the EB exposure apparatus, there
is also desired a method using an electrostatic chuck, the structure of which is
simpler than that of a mechanical fixation and which has a less problem of generating
dust particles.
SUMMARY OF THE INVENTION
According to the present invention, for solving the problems
mentioned above, there is provided an electrostatic chuck which can electrostatically
attract an insulative substrate, such as a glass substrate, under a vacuum atmosphere
and a heating/cooling apparatus and a temperature controller apparatus for an insulative
substrate using such an electrostatic chuck.
In the electrostatic chuck according to the present invention,
the distance between a plurality of electrodes which are provided on one side of
a dielectric constructing the electrostatic chuck is made small, and the thickness
of the dielectric is made thin. A potential difference is given between the electrodes
so as to form an ununiform electric field upon an attracting surface of the dielectric.
An insulative material to be processed being within the ununiform electric field
is partially polarized, and generates gradient force that is attracted in the direction
being strong in the strength of the electric field. The gradient force is expressed
by F∝ &agr; · grad E2, wherein F is gradient force, &agr;
an inductive polarization charge, and E an electric field. The present invention
utilizes this effect.
For obtaining the effect mentioned above, according to
the present invention described in the present claims 1 to 10, there is provided
an electrostatic chuck for attracting an insulative substrate, used under a vacuum
atmosphere by specifying the shape and the properties of a dielectric, and the shapes
of electrodes.
According to the present invention described in the present
claims 14 and 15, there is provided a heating/cooling apparatus, comprising the
electrostatic chuck mentioned above, a plate in which a flow passage is formed to
supply or diffuse heat generated in the process or heat to be supplied to an insulative
substrate by a medium, and a gas supply conduit for supplying a gas which is enclosed
within a space defined between the insulative substrate and the attracting surface
of a dielectric for adjusting heat transmission therebetween, wherein the pressure
of the enclosed gas can be adjusted by the temperature of the insulative substrate
and thereby the temperature can be adjusted to a predetermined value.
According to the present invention described in the present
claims 11, 13, 18 and 19, there is provided a processing method for an insulative
substrate under a vacuum atmosphere, using the electrostatic chuck mentioned above.
According to the present invention described in the present
claims 20 to 23, there is provided an apparatus for electrostatically attracting
an insulative substrate under a vacuum atmosphere, using the electrostatic chuck
mentioned above.
BRIEF DESCRIPTION OF THE DRAWINGS
- FIG. is a plane view showing an example of an electrostatic chuck;
- FIG. 2 is a cross-sectional view along with a cutting line A-A in FIG. 1;
- FIG. 3 is a cross-sectional view of another embodiment in which an insulative
substrate is attracted by an electrostatic chuck;
- FIG. 4 is a view showing an example of a pattern of electrodes provided on a
dielectric;
- FIG. 5 is a view showing another example of a pattern of electrodes provided
on a dielectric;
- FIG. 6 is a view showing another example of a pattern of electrodes provided
on a dielectric;
- FIG. 7 is a graph showing the relationship between the heating/cooling gas pressure
and the temperature of an insulative substrate;
- FIG. 8 is a graph showing the relationship between the voltage applied to an
electrostatic chuck and the temperature of an insulative substrate; and
- FIG. 9 is a graph showing the relationship between the area ratio of a solid-body
contact portion to an electrostatic chuck and the temperature of an insulative substrate.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT(S)
Hereinafter, embodiments according to the present invention
will be fully explained with reference to the attached drawings. FIG. 1 is a plane
view showing ao example of an electrostatic chuck according to the present invention
and FIG. 2 is a cross-sectional view thereof.
In an embodiment shown in F1G. 2, a dielectric layer 1a
and an insulative support base plate 1b are comprised of the same material, and
integrally formed with a layer-laminated structure. FIG. 3 is a cross-sectional
view showing the condition of attracting an insulative substrate 10 by an electrostatic
chuck 1. By applying voltage to electrodes 7 through conductors 12 for applying
voltage, an attracting force is generated between the insulative substrate 10 and
the electrostatic chuck 1, thereby attracting the insulative substrate 10 at protrusions
2 and an outer peripheral seal ring 3 (hereinafter, collectively referred to as
a "solid-body contact portion"). Also, the electrostatic chuck 1 is connected through
a connector portion 11 onto a metal plate 6, and heating/cooling is conducted to
the electrostatic chuck 1 by passing a medium through a medium flow passage 8 which
is provided within the metal plate 6.
FIGS. 4 through 6 show various examples of a pattern of
the electrodes 7 which are formed on one surface of the dielectric. By using the
electrodes 7 with a plurality of pairs, radio-frequency current which is used in
a plasma process for SOS or SOI wafers can be dispersed into each of the electrodes,
thereby enabling to reduce a load for each of electrically conductive terminals
or the like.
Gas is supplied through a gas supply conduit 13 from a
gas supply opening 5 and enclosed within a gas enclosure portion 9. In order to
quickly and uniformly enclose the gas, grooves 4 are formed on the surface of the
electrostatic chuck 1. Through the gas enclosure portion 9 and the solid-body contact
portion, heat transmission is conducted between the insulative substrate 10 and
the electrostatic chuck 1.
With the provision of a gas pressure gauge 16 in the vicinity
of the gas supply conduit, signal voltage is outputted in the range of 0 to 10 V
by pressure:
In the gas conduit, a pressure control valve 17 is provided,
and opened and closed by comparing the signal voltage of the gas pressure gauge
16 with a preset value, thereby enabling to adjust the pressure of the gas to the
preset value.
The measurement results of the electrostatically attracting
force in a case of changing the properties of the dielectric are shown in Table
1.
TABLE 1
No.
Scope Of Present Invention
Dielectric Material
Material To Be Attracted
Thickness (µm)
Resistivity Of Dielectric (&OHgr;cm)
Relative Dielectric Constant Of Dielectric
Surface Roughness Of Dielectric Ra (µm)
Electrostatically Attracting Force (g/5cm2)
1A
○
Al2O3-Cr2O3-TiO2
Ceramic Sintered Body
Low Alkaline Glass, Substrate Thickness 0.6 mm, Relative Dielectric
Constant 5
500
1010
9
0.25
>300
1B
○
Al2O3-Cr2O3-TiO2
Ceramic Sintered Body
Low Alkaline Glass, Substrate Thickness 0.6 mm
500
1011
9
0.25
>300
1C
○
Al2O3-Cr2O3-TiO2
Ceramic Sintered Body
Low Alkaline Glass, Substrate Thickness 0.6 mm
500
1012
9
0.25
>300
1D
○
Al2O3-Cr2O3-TiO2
Ceramic Sintered Body
Low Alkaline Glass, Substrate Thickness 0.6 mm
500
1013
9
0.25
>300
1E
○
Al2O3-Cr2O3-TiO2
Ceramic Sintered Body
Low Alkaline Glass, Substrate Thickness 0.6 mm
1000
1011
9
0.25
>300
1F
○
Al2O3-Cr2O3-TiO2
Ceramic Sintered Body
Low Alkaline Glass, Substrate Thickness 0.6mm
500
1011
9
0.4
250
1G
○
Al2O3-Cr2O3-TiO2
Ceramic Sintered Body
Low Alkaline Glass, Substrate Thickness 0.6mm
500
1011
9
1.0
50
1H
○
Al2-O3-Cr2O3-TiO2
Ceramic Sintered Body
Quartz Glass, Thickness 5 mm, Relative Dielectric Constant
4
500
1011
9
0.25
>300
1I
○
Al2O3-Cr2O3-TiO2
Ceramic Sintered Body
Sapphire, Thickness 0.5 mm, Relative Dielectric Constant 10
500
1011
9
0.25
>300
1J
○
Al2O3-Cr2O3-TiO2
Ceramic Sintered Body
High Dielectric Substrate (Relative Dielectric Constant 120,
Thickness 0.5 mm)
500
1011
9
0.25
>300
1K
○
Al2O3-Cr2O3-TiO2
Ceramic Sintered Body
High Dielectric Substrate (Relative Dielectric Constant 10,000,
Thickness 0.5 mm)
500
1011
9
0.25
>300
1L
○
Al2O3-Cr2O3-TiO2
Ceramic Sintered Body
Polyimide Film (Thickness 50 µm)
500
1011
9
0.25
100
1M
○
Al2O3-Cr2O3-TiO2
Ceramic Sintered Body
SOI Wafer
500
1011
9
0.25
>300
1N
○
Al2O3-Cr2O3-TiO2
Ceramic Sintered Body
SOS Wafer
500
1011
9
0.25
>300
1O
○
Al2O3-Cr2O3-TiO2
Ceramic Sintered Body
Polycrystal Alumina substrate, Thickness 0.6 mm. Surface Roughness
Ra 0.1 µm, Relative Dielectric Constant 10
500
1011
9
0.25
>300
1P
○
Al2O3-Cr2O3-TiO2
Ceramic Sintered Body
Polycrystal Alumina Substrate, Thickness 0.6 mm, Surface Roughness
Ra 0.4 µm, Relative Dielectric Constant 10
500
1011
9
0.25
>300
2
○
Al2O3 Ceramic Sintered Body
Low Alkaline Glass, Substrate Thickness 0.6 mm
500
1015
9
0.1
100
3
○
BaTiO3 Ceramic Sintered Body
Law Alkaline Glass, Substrate Thickness 0.6 mm
500
1011
120
0.1
150
4
○
BaTiO3 Ceramic Sintered Body
Low Alkaline GLass, Substrate Thickness 0.6 mm
500
1010
10,000
0.2
100
5
○
BaTiO3 Ceramic Sintered Body
Low. Alkaline Glass, Substrate Thickness 0.6 mm
500
109
20,000
0.3
100
6
○
SiC Ceramic Sintered Body
Low Alkaline Glass, Substrate Thickness 0.6 mm
500
1010
120
0.1
>300
7
○
Silicon Rubber
Low Alkaline Glass, Substrate Thickness 0.6 mm
500
1010
3
0.4
150
In the measurement of the electrostatically attracting
force, a material to be attracted having an area of 5 cm2 was prepared,
DC voltage in the range of 3 to 10 KV was applied to the electrostatic chuck. When
the material to be attracted started moving against the electrostatically attracting
force by applying force to the material to be attracted in the horizontal direction,
the moving force was measured by a spring scale. Because the maximum load of the
spring scale was 300g, it was impossible to measure force being larger than that.
However, if the coefficient of static friction between the dielectric and the material
to be attracted is 0.2, the electrostatically attracting force will correspond to
reaction about five (5) times as large as the measured value. Therefore, the electrostatically
attracting force will correspond to the tensile strength of 300g/cm2
in the case where the measured value is 300g/5cm2. This value corresponds
to about 30 kPa, which is enough to attract the material to be attracted within
a vacuum chamber. In order to make the shape of the dielectric uniform, it was set
to be 1 mm in the width of the electrode, 1 mm in the distance between the electrodes,
and 0.5 mm in the thickness of the dielectric.
1A through 1D and 2 show the electrostatically attracting
force in a case of varying the resistivity of the dielectric substrate. The resistivity
does not have an influence to the electrostatic force very much; however, it is
preferable that the resistivity be less than or equal to 1013 &OHgr;
cm, which creates larger electrostatically attracting force.
1F and 1G show the electrostatically attracting force in
a case of varying the surface roughness of the dielectric substrate. Compared to
1B, it is preferable that the surface roughness be less than or equal to Ra 0.25
µm.
The surface roughness of the material to be attracted used
in the present embodiment is less than or equal to Ra 0.1 µm, except for the
substrate of polycrystal alumina in 1P.
1B and 2 through 6 show the electrostatically attracting
force in a case of varying the dielectric material. As the properties of the dielectric,
the resistivity rather than the relative dielectric constant has a larger relationship
to the electrostatically attracting force. With regards to the dielectric material,
the most stable and large attracting force can be achieved by using ceramic sintered
body obtained by adding chromium oxide and/or titanium oxide to alumina, and the
material obtained by adding a sinter assisting material thereto.
1B and 1H through 1N show the electrostatically attracting
force in a case of varying the kind of the material to be attracted. The result
shows that different insulative materials can be electrostatically attracted, and
that the larger the relative dielectric constant of the material to be attracted,
the larger the force.
In 10 and 1P, a substrate of polycrystal alumina is used
as a material to be attracted, the surface roughness thereof is varied, and then
the electrostatically attracting force is measured. The result shows that the sufficient
force can be obtained if the surface roughness of the material to be attracted is
around Ra 0.4 µm Therefore, when the relative dielectric constant of the material
to be attracted becomes large, the surface roughness of the material to be attracted
can be degraded.
2 through 7 show the electrostatically attracting force
in a case of varying the dielectric material. The result shows that the sufficient
force can be obtained if a material other than ceramic sintered body obtained by
adding chromium oxide and/or titanium oxide to alumina is used. In a case of glass
for a PDP as a material to be attracted, it is preferable to use a material of rubber
group which is hard to damage the glass is effective from the viewpoint of visibility.
In the present embodiment, silicon rubber is used; however, natural rubber, chloroprene
rubber, butyl rubber, nitrile rubber, fluorocarbon rubber, or resin such as polyurethane,
PTFE, or the like, may be used. In this instance, it is preferable that the volume
resistivity thereof be less than or equal to 1013 &OHgr;cm.
Table 2 shows the relationship between the electrostatically
attracting force with respect to a glass substrate and the applied voltage (10 kV)
in a case of using ceramic sintered body obtained by adding chromium oxide and/or
titanium oxide to alumina, and varying the pattern of the electrodes in the electrostatic
chuck according to the present invention.
TABLE 2
No.
Scope Of Present Invention
Thickness of Dielectric (µm)
Width of Electrodes (mm)
Distance Between Electrodes (mm)
Electrostatically Attracting Force (g/5cm2)
10KV
7
×
300
0.3
0.3
Break down
8
○
300
0.5
0.5
Break down
9
○
300
0.7
0.7
>300
10
○
300
1.0
1.0
>300
11
○
300
2.0
2.0
180
12
×
300
3.0
3.0
30
13
○
300
0.5
1.0
>300
14
○
300
0.5
1.5
200
15
○
300
2.0
1.0
250
16
○
300
4.0
1.0
120
17
×
300
6.0
1.0
30
18
×
400
0.3
0.3
Break down
19
○
400
0.5
0.5
>300
20
○
400
0.7
0.7
>300
21
○
400
1.0
1.0
>300
22
○
400
2.0
2.0
120
23
×
400
3.0
3.0
30
24
○
400
05
1.0
>300
25
○
400
0.5
1.5
200
26
○
400
2.0
1.0
200
27
○
400
4.0
1.0
100
28
×
400
6.0
1.0
20
29
×
500
0.3
0.3
Break down
30
○
500
0.5
0.5
Break down
31
○
500
0.7
0.7
>300
32
○
500
1.0
1.0
280
33
○
500
2.0
2.0
100
34
×
500
3.0
3.0
20
35
○
500
0.5
1.0
>300
36
○
500
0.5
1.5
200
37
○
500
2.0
1.0
165
38
○
500
4.0
1.0
45
39
×
500
6.0
1.0
25
40
×
700
03
0.3
Break down
41
○
700
0.5
0.5
240
42
○
700
0.7
0.7
240
43
○
700
1.0
1.0
220
44
○
700
2.0
2.0
90
45
×
700
3.0
3.0
20
46
○
700
0.5
1.0
260
47
○
700
0.5
1.5
150
48
○
700
2.0
1.0
140
49
○
700
4.0
1.0
50
50
×
700
6.0
1.0
20
51
×
1,000
0.3
0.3
Break down
52
○
1,000
0.5
0.5
200
53
○
1,000
0.7
0.7
200
54
○
1,000
1.0
1.0
180
55
○
1,000
2.0
2.0
70
56
×
1,000
3.0
3.0
20
57
○
1,000
0.5
1.0
220
58
○
1,000
0.5
1.5
120
59
○
1,000
2.0
1.0
120
60
○
1,000
4.0
1.0
30
61
×
1,000
6.0
1.0
10
62
×
2,000
0.3
0.3
Break down
63
○
2,000
0.5
0.5
170
64
○
2,000
0.7
0.7
130
65
○
2,000
1.0
1.0
100
66
○
2,000
2.0
2.0
10
67
×
2,000
3.0
3.0
10
68
○
2,000
0.5
1.0
120
69
○
2,000
0.5
1.5
30
70
○
2,000
2.0
1.0
70
71
○
2,000
4.0
1.0
30
72
×
2,000
6.0
1.0
10
In a case of the pattern having the same width of the electrode
and the same distance between the electrodes, the maximum electrostatically attracting
force can be obtained when the thickness of the dielectric is 0.3 mm, and there
is a tendency that the thinner the thickness thereof, the larger the electrostatically
attracting force.
If both of the width and the distance are equal to or greater
than 0.5 mm, the electrostatically attracting is available. However sufficient insulation
between the electrodes cannot be achieved if the distance between the electrodes
is smaller than 0.5 mm. As a result of this, there are cases where the electrostatically
attracting cannot be obtained.
In a case of comparing the dielectric having the same thickness,
the smaller the width of the electrode, the larger the electrostatically attracting
force.
In a case where the distance between the electrodes is
larger than 2 mm, the electrostatically attracting force can hardly be obtained.
In the present embodiment, the voltage applied is raised to 10 kV. It is expected
that the sufficient force can be obtained even if the distance between the electrodes
is 2 mm, by applying voltage being larger than that.
In a case of comparing the dielectric having the same thickness
and the same width of the electrode, there is a tendency that the electrostatically
attracting force becomes small when the distance between the electrodes is larger
than the thickness of the dielectric.
The foregoing show that a large electrostatically attracting
force can be obtained in a case where the thickness of the dielectric is thin, the
width of the electrode is small, and the distance between the electrodes is almost
equal to the width of the electrode.
In a case of electrostatically attracting a glass substrate
as a material to be attracted, it can be put to practical use by setting the thickness
of the dielectric in the range of 03 to 2.0 mm, the distance between the electrodes
in the range of 0.5 to 1.0 mm, the width of the electrode in the range of 0.5 to
4.0 mm, and the resistivity of the dielectric to be less than or equal to 1013
&OHgr;cm. It is more preferable that the thickness of the dielectric be in the
range of 0.3 to 1.0 nun, the distance between the electrodes in the range of 0.5
to 1.0 mm, the width of the electrode in the range of 0.5 to 1.0 mm, and the resistivity
of the dielectric to be less than or equal to 1013 &OHgr;cm.
Hereinafter, an embodiment of a substrate heating/cooling
apparatus will be described.
FIGS. 7 through 9 are graphs showing data on thermal attraction
experiments and cooling experiments on an insulative substrate. A glass substrate
(i.e., a low alkaline glass) is used as the insulative substrate 10.
FIG. 7 is a graph showing the relationship between the
temperature of an insulative substrate and the pressure of the gas for heating/cooling
to be supplied into a space between the insulative substrate and the attracting
surface of the dielectric, in which the insulative substrate is positioned in a
substrate heating/cooling apparatus which is provided within a vacuum chamber. The
thermal characteristic in a case where a heat flow of 2W/cm2 is supplied
from the upper surface of the insulative substrate 10 is shown by expressing the
pressure of the above-mentioned gas on x-axis and the surface temperature of the
insulative substrate 10 on y-axis. This graph shows that the temperature of the
insulative substrate 10 can be controlled by varying the gas pressure enclosed in
a gas enclosure portion 9. He gas is mainly used in the present experiment; however,
the same heating/cooling effect can be obtained by using Ar or N2.
In order to increase efficiency of the heating/cooling
by supplying higher pressure, it is necessary to make the height of the protrusions
2 on the attracting surface of the dielectric 19 low and thereby bring the pressure
of the gas into the region of a molecular flow. For example, in order to bring the
above-mentioned gas in the range of 0 to 13329 Pa (0 to 100 Torr) into the region
of a molecular flow, the height of the protrusions 2 may be set to be less than
or equal to 5 µm. In this instance, in order to quickly and uniformly enclose
the above-mentioned gas, the formation of the grooves 4 is important as well as
the protrusions 2.
In a case where only the protrusions are formed on the
surface of the electrostatic chuck, it takes time until the pressure within the
space comes to be uniform depending upon the height of the protrusions. Therefore,
by forming of the grooves from the gas supply opening, the time is reduced until
the pressure within the space comes to be uniform. With regards to the shape and
the pattern of the grooves, the effect can be achieved when they are formed in a
radial pattern from the gas supply opening, and they are equal to or greater than
1.0 mm in the width and equal to or greater than 50 µm in the depth. Preferably,
the width is equal to or greater than 1.5 mm and the depth is equal to or greater
than 250 µm, and thereby the time until the pressure distribution in the shape
comes to be uniform is less than or equal to 5 seconds. The effect can be further
increased if the grooves are formed in a concentric pattern as well as a radial
pattern.
As shown in FiG. 8, by varying the applied voltage, it
is possible to vary the temperature of the insulative substrate 10. In this instance,
by varying the surface roughness of the electrostatic chuck, it is possible to adjust
the temperature of the insulative substrate 10.
Further, as shown in FIG. 9, the experiment result shows
that the temperature of the insulative substrate 10 is varied by varying the ratio
of a contact area. In order to vary the contact area ratio, it is necessary to vary
the number and the diameter of the protrusions. The diameter of the protrusions
in the present embodiment is 5 mm, and the width of the seal ring is 4 mm. The number
of the protrusions is converted from the contact area ratio. The protrusions are
distributed upon the surface of the electrostatic chuck in the substantially equal
position with regards to each other.
The present embodiment shows that large heating/cooling
effect on the insulative substrate 10 can be obtained by enclosing the high gas
pressure of 6664 Pa (50 Torr) in the gas enclosure portion 9. However, in order
to enclose such high gas pressure, it is necessary that the electrostatic chuck
generate a large attracting force. For, example, in order to enclose the gas pressure
of 1333 Pa (10 Torr) in a case where the contact area ratio is 20 %, theoretically,
the attracting force of at least 13 g/cm2 is required. Therefore, the
electrostatic chuck having a very large attracting force is required. As a material
for an insulating layer of the electrostatic chuck is used ceramic sintered body
comprised of mainly alumina, and chromium oxide (Cr2O3), titanium
oxide (TiO2), and a sinter assisting material added thereto in an appropriate
amount. The attracting force in this material is about 300 g/5cm2 under
application of 10 KV, which is the same as 1A - 1C mentioned above, and the tensile
strength in the vertical direction can be assumed to be 300 g/cm2. Even
if the contact area ratio is 20%, it can be ensured that the attracting force is
equal to or greater than 60 g/cm2. Therefore, it is possible to sufficiently
attract the insulative substrate.
A low alkaline glass is used as the insulative substrate
10 in the present embodiment; however, the electrostatic chuck according to the
present invention can in general also be applied to other electrical insulative
substrates and/or films.
With the provision of a heater within the insulative support
base plate of the heating/cooling apparatus for an insulative substrate, and an
optical thermometer, a thermocouple, or another noncontact thermometer as a means
for measuring the temperature on the material to be attracted, the signal outputted
from the measurement apparatus is compared with a predetermined value, and thereby
the temperature of the material to be attracted can easily be controlled. In a case
where the temperature of the insulative substrate cannot directly be measured, it
is possible to maintain the temperature of the insulative substrate based on a data
base in which the gas pressure, the applied voltage, the ratio of the solid-body
contact area, the supplied thermal energy, the flow rate of the medium, the temperature
of the medium, or the like are compiled in advance and linked together.
With the provision of the heating/cooling apparatus for
an insulative substrate according to the present embodiment within a reaction chamber,
it is possible to easily control the temperature in a semiconductor manufacturing
process, in particular, in a plasma CVD for an SOS or SOI, a plasma etching, a sputtering,
or the like.
As is fully explained in the above, according to the present
invention, since a material to be processed can be attracted with the electrostatic
chuck even if it is an insulative material, it is possible to easily heat/cool the
insulative substrate with the heating/cooling apparatus in which the electrostatic
chuck is installed, and thereby it is possible to control the temperature of the
insulative substrate at a predetermined value.