The invention concerns a method for generating electrical
conducting and/or semiconducting structures in two or three dimensions in a composite
matrix, wherein the matrix comprises one or more materials provided in spatially
separate and homogenous material structures, wherein the materials in response to
the supply of energy can undergo specific changes of state which cause transition
from an electrical non-conducting state to an electrical conducting and/or semiconducting
state or vice versa, or a change in the electrical conduction mode of the material,
and wherein each material structure is made in the form of a thin layer. The invention
also concerns a method for erasing globally electrical conducting and/or semiconducting
structures generated in two or three dimensions in a composite matrix, wherein the
matrix comprises two or more material provided in spatially separate and homogenous
material structures, wherein the materials in response to the supply of energy can
undergo specific changes of state which cause transition from an electrical non-conducting
state to an electrical conducting and/or semiconducting state or vice versa, or
a change in the electrical conduction mode of the material, and wherein each material
structure is made in the form of a thin layer. Finally, the invention concerns an
electric field generator/modulator (EFGM) for patterning and generating electrical
conducting and/or semiconducting structures in two or three dimensions in a composite
matrix, wherein the matrix comprises one or more materials respectively provided
in one or more spatially separate and homogenous material structures, wherein the
materials in response to the supplied energy can undergo specific changes of state
which cause transition from an electrical non-conducting state to an electrical
conducting and/or semiconducting state and vice versa, or a change in the conduction
mode of the material, and wherein each material structure is made in the form of
a thin layer.
More particularly the present invention concerns the fabrication
of two- and three-dimensional isolating, resistive, conducting and/or semiconducting
patterns and structures for use in electronic circuits which most particularly consist
of a single or several stacked layers of thin films.
The evolution of microelectronic technology shows a steady
trend towards smaller dimensions and reduced costs of the devices. Well-substantiated
predictions show that the performance is going to increase, while the price per
unit or device will decrease. However, today's microelectronic technology is substantially
based on crystalline silicon and shows an increasing tendency towards diminishing
returns, mainly due to the inherent limitations associated with the complexity of
ultra-high resolution lithography and increasing demands of the material processing.
Extrapolations of the present technologies based on crystalline silicon may hence
not be expected to offer dramatic breakthroughs in regard of either performance
or price and future improvements shall require manufacturing plants and manufacturing
equipment, which are extremely capital-intensive.
Microelectronics based on thin-film technology may on the
other hand confidently be predicted to deliver in the near future products representing
real breakthroughs in regard of performance as well as of price. The shift from
crystalline inorganic semiconductors to microcrystalline, polycrystalline or amorphous
inorganic or organic semiconductors will introduce entirely novel boundary conditions
with regard to the production of microelectronics and particularly by the blanks
having form factors which make large areas possible, i.e. the substrates may be
large sheets instead of wafers cut from blanks of limited size, and great flexibility
with regard to architectures, something which will be essential factors in the expected
development of tomorrow's electronic technology. In the present invention special
emphasis will be placed on the use of organic materials due to the ease whereby
they may be processed with basis in the use of large areas and multilayer blanks
with precisely controllable thickness, as well as their vast potential for chemical
tailoring of the desired material properties.
Particularly before the use of electronics based on amorphous
materials can fulfil their expected potential, further developments in certain areas
are required. In the recent years an effort has been made to improve the semiconducting
properties of organic semiconducting thin-film materials, which have given dramatic
and rapid increase in the transistor performance up to a point where organic-based
transistors may now compete with transistors based on amorphous silicon (see for
instance Y.-Y. Lin, D.J. Gundlach, S.F. Nelson and T.N. Jackson, "Pentacene-Based
Organic Thin Film Transistors", IEEE Transactions on Electron Devices, August 1997).
Other on-going projects will lead to coating processes for thin film in order to
generate organic and amorphous silicon semiconductors at low temperatures and with
compatibility to a broad range of organic and inorganic substrate materials. This
has lead to the development of extremely cheap electronic devices with large areas
based on the use of high-volume manufacturing methods.
In spite of this development a wholly satisfactory solution
to how the fabrication technology shall be adapted and made suitable for a low-cost
flexible high-volume production of electrical connections in the thin-film structures
forming the electronic circuits is still lacking. Currently thin-film devices are
based on amorphous silicon manufactured with current paths and conductors patterned
with traditional methods such as lithography and vacuum metallization. The latter
method has formerly also been applied to circuits for demonstration of organic-based
semiconductor thin-film devices (see for instance
A.R. Brown & al. "Logic gates made from polymer transistors and their use
of ring oscillators", Science 270: 972-974 (1995)
). Alternatively, screen printing with conducting "ink" has been used to
make transistors on flexible polymer substrates (see for instance
F. Gamier & al., "All-polymer field-effect transistor realized by printing
techniques", Science 265:1884-1886 (1994)
). Even though lithography may provide high resolution, it is relatively
complex and includes typically wet chemistry steps which are undesirable in high-volume
production of multilayer organic thin-film structures. Screen printing with ink
is also far from ideal, as it only provides low to moderate resolution besides being
a "wet" method.
As examples of prior art such it is evident from available
patent literature may also be mentioned
US patent No. 5 043 251
(Sonnenschein & al.) which discloses a process for three-dimensional lithography
of amorphous polymers for generating a momentary permanent pattern in a polymer
material and which comprises steps for providing doped non-crystalline layers or
films of a polymer in a stable amorphous state under humane operating conditions.
In manufacturing the patterns the film is masked optically and is exposed through
the mask to radiation with sufficient intensity to cause ablation of the exposed
portions such that a distinct three-dimensional imprint is generated in the film.
This process has among other been proposed for use in the manufacture of an optical
data storage disk. Further there is from
US patent No. 5 378 916 (Mantell
) known a photo-sensitive device in the form of a single-crystal structure,
wherein different portions of the structure may have different compositions. Particular
the structure forms a two-dimensional array and a first photosensitive portion comprises
a material which generates electron-hole pairs when it is exposed to light within
a predetermined first wavelength range, while another photosensitive portion comprises
a material which is adapted to generate electron-hole pairs when it is exposed to
light within another wavelength range distinctively different from the first wavelength
range. Yet further there is from
US patent 5 677 041 (Smayling
) known a transistor device which is made by forming a doped layer of radiation-sensitive
material on a substrate. The radiation-sensitive material may among others be polyimid,
polymer, an organic dielectric, a conductor or a semiconductor. The substrate may
be silicon, quarts, gallium arsenide, glass, ceramic, metal or polyamid. A neutral
or undoped layer of another radiation sensitive material is formed over the doped
layer. First and second source/drain areas are then formed in the neutral layer
and extend down to a top portion of the doped layer. A gate area is formed in the
top portion of the neutral layer between the first source/drain area and the second
source/drain area such that a channel area in the doped layer is provided under
the gate area. Drain/source and gate electrodes as formed by irradiation of the
uppermost neutral layer through a mask patterned in accordance with the desired
electrode pattern and realized such that it intensity-modulates the radiation. In
addition the mask may also be realized as a phase-shifting mask.
Finally there is from the article "
Polymeric integrated circuits and light-emitting diodes" of D.M. de Leeuw
& al., IEDM, pp. 331-336 (1997
) known a MISFET wholly realized in polymer and with the use of polymer
materials which are given the desired electrical properties by an exposure to UV
radiation. In the manufacture photochemical patterning of doped electrical conducting
polyaniline films, so-called PANI thin films is used. The films are dissolved in
a suitable solution, whereafter a photo-initiator is added to the solution which
has been deposited on a suitable substrate such as a polyimide film. By thereafter
exposing the PANI film to deep UV radiation through a mask the initially conducting
polyaniline is converted in the exposed areas to the non-conducting leucoemeraldine
form. The starting point here is accordingly a conducting polymer material, the
area resistance of which initially is 1 kiloohm/square, but which after the exposure
obtains an area resistance of more than 1013 ohm/square. In this manner
dielectric structures may be generated in an otherwise conducting matrix. Fig. 1
shows a MISFET according to Leeuw & al. comprising a polyimide substrate 1 with
a PANI thin film which after exposure to UV light through suitable masks forms isolating
structures 6 in the otherwise conducting thin-film material 3. The still conducting
areas 3 in the PANI film define respectively the source and drain electrode of a
MISFET transistor. Above the PANI film a further layer 4 is deposited in the form
of a thin film of polythienylenevinylene or PTV which is an organic semiconductor
material. This layer 4 substantially determines the electrical parameters of the
MISFET transistor. A film 5 of polyvinyl phenol PVP which forms the gate isolator
of the transistor and is opaque to UV radiation and visible light is deposited over
the PTV film 4. Another PANI film is again deposited on the top of the PTV film
5 and patterned by radiation with UV light such that isolating structures 6 are
formed. A still electrical conducting area 2 forms the gate electrode of the MISFET
structure.
If several transistors of this kind as mentioned above
shall be combined in integrated circuits realized in the form of stacked film layers,
vertical current paths between for instance source and drain electrodes in a transistor
and the gate electrode in another transistor must be used. Such vertical current
paths may in principle be realized mechanically, for instance by depositing a metal
film over vertically etched steps in the structure. Otherwise a close analogy is
the use of throughplated holes in circuit boards for realizing a vertical connection
between current paths on the upper and lower side of the circuit board.
The main object of the present invention is to provide
improved fabrication methods for conducting connections and electrodes in microelectronic
components and particularly microelectronic devices with large areas on flexible
substrates by means of processes which combine high-volume fabrication at low costs.
Particularly, it is an object of the invention to provide such fabrication methods
that they may be used on layered physical devices, for instance in the form of a
large number of adjacent stacked thin-film layers, thus generating three-dimensional
circuit structures. The present invention will thereby make possible flexible and
cheap, but simultaneously also singularly simple and precise fabrication of devices
such as flat display devices, logic circuits, memory devices etc.
Further it is also an object of the invention to provide
a method for erasing such three-dimensional circuit structures in situ, such that
the material in the structures is converted back to an initial virgin state whereafter
it by means of a suitable method may be reconfigured in the form of electrical conducting
and/or semiconducting structures in three dimensions, but for instance with another
pattern or another structure than the original.
The above-mentioned features and advantages are realized
according to the present invention with a method which is characterized by applying
to the separate layer a spatially modulated electric field generated by a potential
difference with given field strength and/or characteristics adapted to the specific
response of the material to the energy supplied by the field, the applied electric
field being spatially modulated according to a determined protocol which represents
a predetermined pattern of electrical conducting and/or semiconducting structures
in the relevant material structure, whereby in the layers in response to the energy
supplied by the field two-dimensional electrical conducting and/or semiconducting
structures are generated with the pattern predetermined by the protocol, and then
optionally providing two or more layers in a stacked configuration, such that the
composite matrix formed by separate adjacent layers is provided with electrical
conducting and/or semiconducting structures in three dimensions.
Further it is according to the invention advantageous that
the electric field generated by a potential difference is modulated spatially in
a plane substantially parallel with a layer by means of an electrode device with
patterned electrodes, the electrode device by selective supply of voltage to the
electrodes according to the determined protocol generating electrical point or line
potentials, which generate the electrical conducting and/or semiconducting structures.
It is according to invention advantageous that the stacked
configuration is formed by two or more layers after generating the electrical conducting
and/or semiconducting structure in each layer being combined into laminated multilayer
structures which forms the composite matrix with electrical conducting and/or semiconducting
structures in three dimensions.
It is according to the invention also advantageous positioning
the multilayer formed by a lamination of two or more self supporting layers into
a stacked configuration. A layer is after the lamination to adjacent layers then
preferably positioned such that two or more two-dimensional electrical conducting
and/or semiconducting structures in the first-mentioned layer according to the protocol
register with one or more two-dimensional electrical conducting and/or semiconducting
structures in adjacent layers, whereby one or more vertical electrical conducting
and/or semiconducting channels are generated in the cross-direction through the
layers.
Finally, it is according to the invention advantageous
providing an electrical conducting and/or semiconducting structure which forms a
vertical channel through the layer according to the protocol, in electrical conducting
and/or semiconducting connection with one or more two-dimensional electrical conducting
and/or semiconducting structures in this layer, each channel preferably being generated
with a conductivity or conduction mode which is constant between the layers or with
a conductivity or conduction mode which varies between the layers.
A method for global erasing according to the invention
is characterized by applying globally to the composite matrix a electric field generated
by a potential difference with given field strength and/or characteristics adapted
to the specific response of the material to the energy supplied by the field until
the materials in the composite matrix in response to the energy supplied by the
field in their entirety arrive in the electrical non-conducting state.
An electric field generator/modulator is according to the
invention characterized in that it comprises a first electrode means with a plurality
of parallel strip electrodes provided in a plane, a second electrode means with
a plurality of parallel strip electrodes provided at a distance from the first electrode
means and superpositioned thereto in a second plane parallel with the first plane
such that the electrodes mutually are substantially orthogonally oriented in a matrix-like
arrangement, that the electrode means over cross-connection devices are connected
with a controllable power supply, the electrical field generator/modulator in the
space between the electrode means being adapted for receiving a thin-film material
in the form of a discrete component or a continuous tape which without touching
the electrode means continuously or intermittently is fed through the space with
simultaneous positioning and alignment spaced apart from and between the electrode
means in a plane substantially parallel thereto, whereby the electrical conducting
and/or semiconducting structures can be generated according to a determined protocol
and by means of point, line or area potentials created between selected electrodes
in the electrode means when the former over the cross-connection devices are supplied
with electric power. Preferably are the electrodes in each electrode means provided
on or in surfaces of respective substrates facing each other and/or in that connection
preferably made as a part of the substrates and form conducting structures in the
substrate material.
Further it is according to the invention advantageous that
the distance between the electrode means is controllable depending on the thickness
of the thin-film material.
Finally it is according to the invention advantageous that
the electrodes in each electrode means are provided with a mutual distance between
0.1 µm and 1.0 µm and that the electrodes in each electrode means are
formed with substantially constant width of 0.1 µm to 1.0 µm.
The invention shall now be explained in more detail in
connection with a survey of its basic principles and with the use of exemplary embodiments
in connection with the appended drawings, wherein
- fig. 1. shows a MISFET with the electrodes formed of photo-convertible material
according to prior art,
- fig. 2a, b schematically respectively in section and plan view an embodiment
of the electric field generator/modulator (EFQM) according to the invention and
its use in a first step in the method for generating according to the invention,
- fig. 2c, d schematically in respectively section and plan view EFGM as shown
in fig. 2a, b and used in a second step in the method for generating according to
the invention,
- fig. 2e, f schematically in respectively section and plan view EFGM as shown
in fig. 2a, b and used in a third step of the method for generating according to
the invention,
- fig. 3 schematically the embodiment of the method for generating according to
the invention, combined with a lamination of single layers into a multilayer structure,
- fig. 4 a section through a multilayer structure with conducting and/or semiconducting
structures as generated by the steps shown in fig. 2a-f,
- fig. 5 a schematic section through a laminated multilayer structure which comprises
conducting and/or semiconducting structures generated by the method according to
the present invention,
- fig. 6 a schematic section through a diode structure generated by the method
according to the present invention,
- fig. 7 a schematic section through a MOSFET structure generated by the method
according to the present invention,
- fig. 8 a schematic section through a logic inverter structure based on the MOSFET
structure in fig. 7 and generated by the method according to the present invention,
- fig. 9 the equivalent diagram of an AND gate realized in CMOS technology,
- figs. 10a-d in plan view sublayers in an AND gate structure generated by the
method according to the invention and according to the equivalent diagram in fig.
8 with the use of MOSFET structures as shown in fig. 7,
- fig. 11 the AND gate structure in fig. 10 as a stacked multilayer configuration,
but exploded in the separate sublayers,
- fig. 12 schematically another variant of the AND gate structure in fig. 10 and
with the separate MOSFET structures provided mutually connected in a vertical configuration.
Now the basic principles of a method according to the present
invention whereby three-dimensional structures with a well-defined mode and degree
of electrical conduction are generated by spatially controlled patterning in situ
in convertible materials (CM) which have such properties that their electronic properties
are converted reversibly or irreversibly under the effect of radiation, heat, or
electric fields. The method for generating such structures according to the present
invention is based on the use of electric fields, either direct current fields or
alternating current fields. Initially the three-dimensional electrical conducting
and/or semiconducting structures can be generated as two-dimensional structures
of this kind by direct local influence of the electric field on a single layer and
appears as three-dimensional by joining single layers into a multilayer structure.
Typically an electric field-convertible material (EFCM) will be an organic material,
for instance a molecule, an oligomer or a polymer where a phase transition from
an initial first state to a new second state takes place upon being subjected to
an electric field, for instance of a given field strength or with a given frequency.
As mentioned in the following, it is presupposed that the most important change
taking place from the first to the second state, is the degree of electrical conduction.
In the following the method for generating and erasing of electrical conducting
and/or semiconducting structures by means of electric fields shall be discussed
both generally and more specifically in connection with a description of the figures.
For polymers such as polyaniline there are as shown in
the above-mentioned paper by de Leeuw & al., observed conduction ratios between
two states as high as 1010. In this case it concerned in situ conversion
of a single layer of irradiation convertible material from conducting to non-conducting
state in order to generate electrical connections in a single electronic circuit.
Electrical conducting connections in doped polyaniline films (PANI films) were defined
by exposure to deep UV radiation through a patterned mask.
A multilayer stack of different electric field-convertible
materials may be provided on a substrate which may be flexible or rigid, conducting
or non-conducting. The field-convertible materials are made conducting, semi-conducting
or isolating in desired patterns by subjecting a number of single layer field-convertible
materials to spatially-controlled electric fields, and with subsequent combination
of the layers into a multilayer stack. Multilayer stacks of field-convertible material
are of particular interest in connection with multilayer thin-film circuits where
it is required to generate electrical conducting lines, current paths, connection
points or electrodes in several layers such that the conducting structures in one
layer has a precisely controlled spatial relationship to the conducting structures
in the layers which are located above or below. One example is thin-film field effect
transistors (TFET) where the source and drain electrode in a layer must be correctly
positioned relative to the gate electrode and with intervening isolating and semiconducting
layers. Another example is electrical connections between the layers where traditional
solutions in many cases are unsatisfactory, for instance by incorporating a number
of steps such as forming open channels or vias between suitable points which then
shall be electrically connected in the different layers and with subsequent filling
or casing of the channels with a conducting material, such as this finds its parallel
in the use of through-plated holes in circuit boards to obtain a connection from
the front to the back of the circuit board. A third instance is the generation of
capacitors by defining conducting areas which are aligned mutually opposite in two
layers separated by an isolating layer. Evidently not only highly conducting, but
also isolating resistive and semiconducting patterns in multilayer structures are
of the greatest importance. Such as will be explained in more detail in the following,
patterns of this kind may be generated by using the method for generating electrical
conducting and/or semiconducting structures or patterns according to the present
invention. With regard to the precision and clarity the following description shall,
however, be introduced by emphasizing on how patterns and three-dimensional structures
which either are very good or very bad electrical conductors shall be defined.
Multilayer structures as described herein are of particular
interest when they are integrated with thin-film semiconductors in order to form
complete circuits. The present standard procedures for fabricating microelectronic
circuits which exploit the semiconducting properties of a common silicon substrate
restrict automatically the realizable architectures to the kind which allows access
to the substrate for all active devices. If the method according to the present
invention is used for generating electrical conducting and/or semiconducting structures
in three dimensions by means of converted stacked single layers, whole devices may
be generated in this manner without any essential restriction with regard to the
size or complexity as scaling quite simply takes place by joining more layers to
the stack. As each layer may be made thin, for instance with an order of magnitude
of 10-100 nm, the resulting volumetric density for the circuit patterns and hence
the performance per weight or volume unit may be extremely high. Further hybrid
architectures may be realized with the use of layers which include electrical field-converted
electronic structures which are formed on the top of and function in cooperation
with traditional silicon-based electronic circuits.
The basic object of the present invention is the generation
of electrical conducting, semiconducting and/or resistive structures in three dimensions
within a multilayer material in monolithic format, as the structures mentioned are
generated with the use of electric fields in the form of point, line or area potentials.
An embodiment of the method for generating with the use of electric field shall
now be described with reference to figs. 2a-f.
Fig. 2a shows a section through an electric field generator/modulator
according to the invention which functions as an electric patterning device for
electric field-convertible materials. The electric field generator/modulator is
realized such that it both generates the field and in addition also can modulate
the fields spatially, i.e. in a plane or two-dimensions and generate electrical
conducting and/or semiconducting structures with the desired pattern in this plane.
In the following will hence the electric field generator/modulator abbreviated be
denoted EFGM. EFGM 20 comprises as shown in fig. 2a in section and in fig. 2b in
plan view a first electrode means E1, consisting of thin parallel electrodes 21
and another electrode means E2 provided spaced apart from the electrode means E1
in a plane parallel thereto. The electrode means E2 consists similarly of thin parallel
electrodes 22 provided such that they are oriented substantially orthogonal to the
electrodes 21 in the electrode means E1. The electrode means E1, E2 are connected
with a power supply 23, here shown as a direct voltage supply, but the power supply
23 may also be an alternating voltage supply. The power supply 23 is connected with
the electrode 21; 22 in the electrode means E1;E2 over respective cross-connecting
devices 21, 24. The distance between the electrode means E1, E2 allows a thin film
of electrical field-convertible material EFCM in fig. 2a denoted SS1 to be inserted
between the electrode means E1, E2, without contacting these. The electrode means
E1, E2 may be formed of self-supporting or supported thin films wherein the electrodes
21, 22 in each case are embedded in the film material. Similarly it is to be understood
that the layer SS1 of the field-convertible material EFCM may be a continuous tape
which is inserted in EFGM 20 between the electrode means E1, E2 in a substantially
continuous movement. By applying voltage e.g. to an electrode 21 in the electrode
means E1 and to an electrode 22 in the electrode means E2 an electric field perpendicular
to the layer SS1 is formed in the intersection between the electrodes 21 and 22
and the field-convertible material SS1 will be able to transfer from a non-conducting
to a conducting state in areas which is influenced by the field between the electrodes
21, 22. If an electrode 21 and another electrode 22 respectively are addressed electrically
in this manner, an approximate point potential is obtained in the intersection between.
If e.g. an electrode 21 in the electrode device E1 and all electrodes 22 in the
electrode device E2 are addressed, a field is obtained substantially in the form
of a line potential along the electrode 21 in question and correspondingly a line-like,
for instance an electrical conducting structure in the layer SS1 which is located
between the electrode devices E1, E2 will be generated. If an number of electrodes
21 which are located juxtaposed to each other in the electrode device E1 and correspondingly
a plurality of electrodes 22 which are juxtaposed to each other in the electrode
device E2, the field which are created between the electrode intersections will
generate an area potential and it may for instance be generated an electric area
structure in the layer SS1. In figs. 2a, 2b such electrical conducting structures
are e.g. generated substantially as area structures, but it is to be understood
that there also may be generated as point of line structures, dependent on the manner
whereby the electric field is generated.
Figs. 2c and 2d show respectively in section and plan view
how EFGM 20 is used for generating for instance electrical conducting structures
9 in a second layer by addressing the electrode means E1, E2 in EFGM 20 in a suitable
manner. Correspondingly figs. 2e,f also shows in section and plan view EFGM 20 with
a third layer SS3 which here for instance is patterned with semiconducting structures
10. As shown in fig. 2a-f the patterning of the field-convertible material EFCM
takes place for each separate layer SS1, SS2, SS3, but these layers may as mentioned
above, be present in the form of self-supporting single films of EFCM and assembled
into a multilayer stack, such this schematically is shown in fig. 3. The fabrication
of circuits realized with electrical conducting and/or semiconducting structures
in EFCM can take place with tapes of EFCM in continuous paths as shown. Each tape
or each film are in fig. 3 shown as three films EFCM1, EFCM2, EFCM3 and are converted
by electric field to the desired spatial pattern in separate EFGM 20 for each of
the paths. Then follows the assembly into a multilayer structure MLS, e.g. by gluing
or heat-assisted lamination. The multilayer structure MLS may well be provided on
a substrate which, of course, is not subjected to any electric field, but is laminated
to the multilayer structure MLS in the same process step. In each case a flexible
tape MLS is obtained which either may be folded or coiled or cut into segments,
for instance to make single circuits. In fig. 3 the field-convertible material EFCM
in the form of three tapes or films EFCM1, EFCM2, EFCM3 is drawn from respective
rolls Ra and conveyed in separate lines by alignment rolls Rb1,
Rb2, Pb3, Rb4 in each line for tensioning and positioning
of the tapes through EFGM 20. The completed patterned films EFCM1, EFCM2, EFCM3
are conveyed over a guide roll set Rc and possibly after a further position
adjustment through a lamination step Rd and laminated into the multilayer
structure MLS. This multilayer structure may as mentioned, include a substrate 1
which is drawn from a further roll Ra in a separate line and is laminated
together with the converted film material EFCM in the lamination step Rd.
For three layers which are laminated together in this manner and converted as shown
in fig. 2a-f, it may then as shown schematically in section in fig. 4 be obtained
a circuit structure which is provided on the substrate 1. The conducting structures
9 and the semiconducting structures 10 contact each other vertically or extend horizontally
in each of the layers SS1, SS2, SS3 as shown and form to gether three-dimensional
structures of this kind in the desired pattern.
The electrode means E1, E2 in the electric field generator/modutalator
(EFGM 20) as for instance shown in fig. 2a and fig. 2b, may be formed in or on substrates
of a non-conducting material and the electrodes 21, 22 may then be provided on the
opposite surfaces of the substrates or embedded in the substrates. They may also
form conducting structures in the substrate material itself. The electrode width
and the mutual distance between the electrodes 21, 22 in each electrode means E1,
E2 will be determining for the spatial resolution in the patterning of the conducting
and/or semiconducting structures and the achievable pitches. In compatibility with
today's semiconductor technology the electrodes 21, 22 thus can be realized with
a width between 0.1 and 1.0 µm and corresponding mutual distances. It is with
present technology wholly possibly to realize electrode widths, e.g. in thin films
provided on substrates, of 0.1 µm or less by nanotechnology, for instance printing
methods, or by means of chemical methods. The circuit patterns which are realized
with EFGM20 with the method according to the present invention will at least be
dimensionally compatible with that which optimally may be achieved by using for
instance microlithography in silicon-based circuit technology, Dependent on the
thickness of thin film material wherein conducting and/or semiconducting structures,
i.e. circuit patterns, shall be generated, the distance between the electrode devices
E1, E2 can be controlled in order to achieve an optimum definition of the potentials
formed between the electrodes. The control may take place via not shown micromechanical
servocontrol means which are well-known to persons skilled in the art. - During
the generation of the circuit pattern the space between the electrodes may besides
be filled with an isolating gas with high dielectric strength in order to prevent
break-down between the electrodes.
As has been demonstrated with candidate materials for field-induced
conversion, the conversion can be performed with a high degree of reproducibility
at well-defined field strength. Typically the field strength necessary to induce
the conversion will be in the order of 5 000 000 V/m, implying a potential difference
over the electrode means E1, E2 in the order of 3-6 volts for film thicknesses in
the 200-300 nm range and a gap between the electrode means E1, E2 large enough to
accommodate films of this thickness. It should also be noted that the electric field
substantially is applied in a direction perpendicular to the thin film, although
in principle it could be applied with other orientations. The former alternative
appears as preferable with regard to the required precision in spatial resolution
as well as obtaining a well-defined field strength.
The power supply 23 in EFGM 20, e.g. as shown in fig. 2a
and 2b, may either be a direct current source or an alternating current source.
Preferably it will be realized as a controlled power supply and be able to supply
the electrode means E1, E2 with current with different modes and characteristics.
For this purpose both the power supply 23 and the cross-connection means 24, 25
hence will be connected with a not shown external control device which may be programmed
according to the protocol for a desired circuit pattern and corresponding control
the generation of the desired electrical conducting and/or semiconducting structures
in the layer material or the thin film material between the electrode means E1,
E2. Protocols and required software may be loaded to the not shown control device
from any external source and it is hence nothing against that the fabrication of
circuits with the use of EFGM 20 may be managed from a distant locality.
There shall now be given a more detailed discussion of
the electric field-convertible materials EFCM which may be used in the method according
to the present invention, as well as specific techniques which may be used in the
embodiment of said method. The basic principle of in situ field-conversion of materials
is to generate conducting and/or semiconducting structures by means of spatially
modulated and/or field strength modulated electric fields. The conversion itself
may additionally be reversible or irreversible. Concrete examples of this will be
given below. It must be mentioned that EFCMs at the time being are in an early development
stage and it is to be expected that ongoing research and development activities
in the field dramatically shall increase the number of available materials.
It is in the present invention particularly preferred using
EFCMs which by being subjected to an electric field remain in this state until they
again are subjected to which brings the material back to the initial state. This
is among other the case of different organic macromolecules and other materials
which generally are known as molecular electronic materials. An instance of a material
of this kind is disclosed in the paper "
A new material for optical, electrical and electronic thin film memories"
by Z.Y. Hua & G.R. Chen, Vacuum, Vol. 43, No. 11: 1019-1023 (1992)
. This material is an organometallic charge-transfer complex M(TCNQ) formed
by TCNQ (7,7,8,8-tetracyanoquinodimetan, C12H4N4)
which functions as an electron acceptor molecule with different metals as electron-rich
donors. The metals may be Li, Na, K, Ag, Cu or Fe. M(TCNQ) may under the application
of electric fields and for the sake of that also energy supplied in the form of
heat or light radiation transfer from a high impedance state to a low impedance
state. Generally the reaction can be written as
The process is reversible, as the return reaction may be
obtained by supplying energy &egr; in the form of heat, electrical fields or photon
radiation. The reversible reaction results in that M(TCNQ) may be used for generating
a bistable switching medium, for instance an erasable memory material. In the method
according to the present invention only electric fields are used and not irradiation.
In thin layers, for instance of 100-200 nm, M(TCNQ) has non-linear current-voltage
characteristics, something which may be used for realizing memories of the type
ROM and RAM. For this purpose it is of particular interest that M(TCNQ) stably and
reproducably allows current-controlled bistable electrical switching. In an electrical
addressable memory for instance the high impedance state may be used for representing
binary 1 and the low impedance state binary 0. The transition time between two such
states is less than 400 ns. - Further examples of relevant materials are discussed
in
W. Xu & al., "Two new all-organic complexes with electrical bistable states",
Appl. Phys. Lett. 67:2241-2242 (1995)
and the therein appended literature references. The materials mentioned
are bistable and have well-defined thresholds for conversion from conducting to
non-conducting state and vice versa with the use of electric fields.
In certain field-convertible materials, including TCNQ,
the conversion from a non-conducting to a conducting state may also take place when
the energy is supplied in the form of the heat. As the field-convertible material
basically is dielectric or strongly resistive, an electric alternating field which
over the electrodes is applied with a suitable frequency to the material, may induce
heat in the potential area and a heating with a subsequent conversion of the material
from a non-conducting to a conducting state in this area may then take place. The
power supply must then be operated as an alternating power supply and the thermal
conversion must be regarded as a secondary effect induced by the electric field.
In order to obtain good spatial definition of the generated electrical conducting
and/or semiconducting structures the thermal field which is induced by the alternating
field in the material must be precisely controlled. The thermal field will namely
propagate through the material and cause a temperature increase which may influence
the electrical properties of the material outside the potential area which ideally
shall define the spatial extent of the generated structure. If the field-convertible
material is regarded as an infinite thin layer, the temperature increase will make
itself felt unto a distance from for instance a point potential which falls together
with the intersection point of the activated electrodes, with a thermal diffusion
length defined by the formula
where the material parameters
- &kgr; = thermal conductivity,
- f= 1/&tgr; the characteristic frequency which is ≅ the inverse of the
pulse duration &tgr;,
- &rgr; = the density of the material, and
- c = the specific heat of the material.
It follows from equation 1 that in order to reduce the
thermal diffusion and obtain a sharp spatial definition of the desired electrical
conducting and/or semiconductor structures, an alternating current pulse should
be used which provides high field strength and a fast temperature increase in the
potential area with subsequent rapid conversion of the field-convertible material.
This may be achieved by combining a high field strength with high field frequency
and with the use of field-convertible materials in the form of thin films with a
thickness of 100 nm it is supposed that an unwanted thermal diffusion effectively
can be avoided by using alternating current pulses of at most a few microseconds.
In this connection the field characteristics must also be tuned to the desired degree
of conductivity on the potential areas which ideally defines the generated conducting
and/or semiconducting structures.
Electrical connections between different layers in thin-film
materials or other types of electronic materials present a major challenge for the
fabrication of microelectronics. Precise positioning of conducting paths in each
layer plane and in the perpendicular direction to the planes is of paramount importance
and comprises typically forming vias or holes which may be filled with conducting
material in order to create connections perpendicular to the layers. The physical
manufacture of the holes in prior art takes place by means of drilling, punching
or etching, and the conducting material is added by mechanical filling, electroplating
etc. Very clearly processes of this kind represent a significant complication and
a substantial cost with an accompanying limited precision.
In the present invention the connections as well as active
and passive devices may be generated in the same processing sequence which defines
the electrical conducting and/or semiconducting structures in each layer, i.e. with
the same kind of spatial precision as the structures themselves and without resorting
to further and other types of manufacturing steps. Fig. 5 shows the basic principle
for the particular case where a single conducting path 9 shall be generated between
a portion of for instance of a conducting structure in a layer SS5 and a portion
of another conducting structure 9 in a layer SS8 spaced apart from the former. By
repeated conversion of a small area in the same location of in each of several adjacent
layers between the termination points of a conducting and/or semiconducting structure,
a column 9' of conducting material is formed as shown in fig. 5 and electrical conductivity
obtained stepwise from the starting layer SS5 which contains the first conducting
structure, to the final layer SS8 which contains the second conducting structure.
The cross-section of column 9' may be defined arbitrarily via the selected electric
field pattern. A number of parallel conducting columns may be generated by direct
extension of this procedure and the columns may begin and end in different layers
such this is apparent from fig. 5. In a given layer which contributes with a conducting
structure 9 in connection with one or more conducting columns of vertical conducting
structures 9', the latter shall be made concurrently with other conducting 9 and/or
semiconducting structures 10 which are patterned in this layer, for instance SS6
in fig. 5, i.e. without having to carry out other or different processing steps.
Typically the degree of conversion from a non-conducting to a conducting state or
vice versa can be controlled by the field strength and/or its time characteristics,
possibly also by the duration of the field. Thus a column which connects points
in two different layers may be formed such that it functions as a resistor in a
circuit by choosing the degree of conductivity in segments from layer to layer along
the column.
A method for erasing electrical conducting and/or semiconducting
structures generated in three dimensions forms a part of the invention.
In principle may electrical conducting and/or semiconducting
structures in single layers be erased selectively with the use of EFGM20 as shown
in any of the figs. 2a-f and suitable spectral modulation. After joining of single
layers into a multilayer structure MLS the erasing at time being can, however, only
be performed globally by the multilayer structure, in case the matrix, globally
is subjected to an electric field with given field strength and/or characteristics
and possibly adapted to the specific response of the material to the energy supplied
by the field. The materials in the matrix will then be reconverted until the matrix
in its entirety arrives in an electrical non-conducting state, something which will
be the case if it e.g. is made of a material such as M(TCNQ). A multilayer structure
or matrix of M(MTCNQ) material may thereafter be reconfigured with new electrical
conducting and/or semiconducting structure, but this is not at present possible
by using electrical fields. However, a method for generating as disclosed by the
simultaneously filed International Patent Application
PCT/NO99/00023
which belongs to the present applicant, may be used.
As the method for generating according to the present invention
makes possible that suitable materials may be converted from an isolating to a semiconducting
state or vice versa by electric fields, either directly or indirectly (e.g. in the
last instance due to a simultaneous local heating), it will be possible to apply
the method to manufacture for instance diodes and transistors which may be connected
electrically with resistances and capacitors to form complete active electronic
circuits. More specific examples of active components and circuits formed thereof
shall be disclosed by the following examples.
Example 1
Fig. 6 shows a forward-biased pn junction diode with conducting
and/or semiconducting structures generated by the method according the invention
and realised in thin-film technology with four sublayers SS 1-SS4. The layers SS2
and SS3 contain the active semiconducting material provided between the electrodes
11 in respectively the sublayers SS1and SS4. The active material 10 in the sublayer
SS2 is an n-doped semiconductor, while the adjacent active material 10' in the sublayer
SS3 is a p-doped semiconductor. The electrodes 11 in the layers SS1 and SS4 are
contacted by horizontal electrical conducting structures or conducting paths 9 in
the same layer. The separate layer in the diode structure in fig. 6 has typically
a thickness of about 100 nm such that the whole structure forms a multilayer structure
with a thickness less than 1 µm. The horizontal extension of the area of the
diode structure will be determined by the spatial resolution which is realized with
the use of an EFGM, but with the electrode means E1, E2 as shown in fig. 2a-f, it
will be possible to form electrodes 21, 22 with pitches in the order of magnitude
0.2-1.0 µm by conventional lithographic methods or by using irradiation convertible
materials and a method as disclosed in the above mentioned international patent
application
PCT/NO99/00023
. Special printing methods or use of nanotechnological and chemical methods
will besides be able to realize electrode structures which are one order of magnitude
smaller. Realistically it may be supposed that with the available technologies for
making the electrode devices it will be possible to modulate point and line potentials
spatially in two dimensions to a smallest extension of 0.1 µm.
Example 2 - MOSFET
Fig. 7 shows schematically a MOSEET for use in the present
invention and realized wholly in organic material in thin-film technology. The gate
electrode 12 is provided in the sublayer SS1 and connected with a horizontal conducting
structure 9, while the sublayer SS2 constitutes the gate isolator 13. The active
semiconducting material 10 is provided in the sublayer SS3 and registers with the
gate electrode 10. The source and drain electrodes 14 are provided in the following
top layer SS4 and are contacted by horizontal electrical conducting structures 9
in the same layer. Each of the layers comprises either electrical conducting structures
and/or a semiconducting structure, as well as dielectric areas. The thickness of
a MOSFET of this kind may be S µm, while the extension in the horizontal
plane such as may be realized with present technology will be from at most a few
µm to less than 1 µm, cf. what is said in example 1.
Example 3 - Logic CMOS inverter
The MOSFET structure in fig. 7 may now be used in logic
gates, for instance a logic inverter in CMOS technology as shown in fig. 8. An inverter
of this kind is formed by parallel connection of the drain and source electrode
in respectively an n-MOSFET and a p-MOSFET in a back-to-back configuration, with
common gate electrode. For this purpose a vertical conducting structure 15 is generated
and passes through all sublayers SS1-SS7 and connects the electrodes 14'. The output
signal from the inverter is conveyed on this conducting structure 15 to a horizontal
connecting structure 9 at left in the figure. The common gate electrode 12 of the
MOSFET receives the input signal via the horizontal conducting structure 9 in the
sublayer SS4 at right in the figure. The thickness of all sublayers will then be
less than 1 µm, typically realized with about a thickness of about 0.7µm,
while the horizontal extension of the inverter will have the same dimensions as
stated above in connection with the discussion of the MOSFET structure in the figure
7.
Example 4 - CMOS AND gate
Active components like the MOSFET structures shown in fig.
7 may be used for forming integrated circuits by stacking of sublayers with structures
which have the desired electrical properties and wholly are realized in an organic
thin-film technology. Specifically the following example is connected with an AND
gate realized in CMOS technology with the use of the transistor structure as shown
in fig. 7. In order to facilitate the understanding of how active devices such as
field-effect transistors may be combined in multilayer structures into functional
devices as for instance logic gates, reference shall be made to fig. 9 which shows
the circuit diagram for an AND gate realized in complementary MOS technology (CMOS
technology). The CMOS AND gate is realized with respectively n-MOSFETS and p-MOSFETS
of the enrichment type as switches. Two input signals A and B are conveyed respectively
to the gate electrodes on p-MOS Q1 and Q2 and the gate electrodes
on n-MOS Q3 and Q4. If both input signals switches A and B
are high, the output signal X will be low. In this case Q3 and
Q4 will both be on and the p-MOS switches Q1 and Q2
will both off, i.e. no current flows and the output signal X hence goes low.
If, on the contrary, either the input signal A or the input signal B is low or both
are low, correspondingly the p-MOS transistors Q1 respectively Q2
will be switched on and the output signal X goes high, as either one or both
of the serially connected n-MOS Q3, Q4 are off and no current
flows. The devices Q1, Q2, Q3, Q4 realize,
as will be seen, a NAND gate and to realize an AND gate it is necessary to connect
the output of the NAND gate with a logical inverter which also is realized in CMOS
technology, respectively with the use of a p-MOS switch Q2 and an n-MOS
Q6 switch connected in parallel. This is a standard CMOS inverter and
if its input signal X is high, its output signal X will be the inverted of
the input signal X and hence low. Conversely a low input signal
X will be inverted to a high output signal X and this corresponds to the
input signals A and B to the NAND gate both being high. In other words it is easily
realized that circuit as shown in fig. 9 realizes an AND gate and persons skilled
in the art will understand that correspondingly logic OR and NOR gates may be realized
and with any number of inputs. However, in principle, all Boolean functions can
be realized in combinations of one type of gate and one or more inverters realized
in CMOS technology, for instance with the use of the transistor structure as shown
in fig. 7.
Purely practically the AND gate can be implemented in thin-film
technology as shown in figs. 10a-10d and with the use of MOSFET structures corresponding
to that shown in fig. 7. Figs. 10a-10d show the AND gate wholly realized in thin-film
technology and with the active and passive devices provided in four sublayers SS1,
SS3-SS5. The first sublayer SS1 (fig. 10a) contains the gate electrodes g1-g6
where the subscript points to the corresponding subscript for the MOSFETs Q1-Q6
in fig. 9. The inputs A and B are conveyed to respectively the gate electrodes g1,
g3 and g2, g4 and via horizontal conducting structures
or current paths 9. Correspondingly the gate electrodes g5, g6
in the inverter are connected with a horizontal current path 9. A vertical electrical
conducting structure is denoted 15, the symbol &Dgr; indicating that it extends
upwards in vertical direction from the sublayers SS1. In fig. 10b the symbols &Dgr;
and ∇ indicate that the vertical conductor structure 15 in the laver SS3
extend vertically through this layer and on both sides thereof. The layer SS3 comprises
areas with active semiconductor materials b1-b6 (corresponding
to 10 in fig. 7) which are assigned to and register with the corresponding gate
electrodes g1-g6 in the layer SS1. - It is to be remarked
that a layer SS2 exclusively, apart from the vertical conductor structure 15 which
also extends through this sublayer on both sides thereof, consists of dielectric
material which forms a common gate isolator for the MOSFETs Q1-Q6
which realize the AND gate. The layer SS2 is, of course, located between SS1 and
SS3, but has been excluded from the drawing. - The layer SS4 fig. 10c is provided
above and adjacent to the layer SS3 and comprises respectively the source electrodes
S1-S6 and the drain electrodes d1-d6
for the corresponding MOSFETs Q1-Q6. The active semiconductor
material d1-d6 which is located in the layer SS3 is here indicated
by stitched lines. The vertical current path 15 also extends also through the layer
SS4 and to both sides thereof and contacts a horizontal current path 9 in the sublayer
SS5 as shown in fig. 10d. This horizontal current path corresponds to the connection
between the drain electrodes d2 and d3 for the corresponding
MOSFETs Q2, Q3 and is additionally also connected with the
drain electrode d1 on Q1. Another horizontal current path
9 realizes the serial connection between the source electrode s3 on Q3
and the drain electrode d4 on Q4. The source electrodes s4
and s6 are grounded over further horizontal conductor structures 9, while
the horizontal conducting structure 9 farthest to right in the layer SS5 is supplied
with a voltage Vdd and connects the source electrodes s1,
s2, s5 on respectively Q1, Q2 and Q5.
A further horizontal current path 9 uppermost in fig. 10d forms the parallel connection
between the drain electrodes d5,d6 on Q5, Q6
and the output line, denoted with X. The output signal X from the NAND gate
consisting of Q1, Q2, Q3, Q4 is conveyed
on the vertical current path 15. Fig. 11 shows schematically how the layers in fig.
10 appear in stacked configuration, the layer SS2 with the gate isolator here being
included. For the sake of clarity the stack, however, is shown exploded in its separate
sublayers SS1-SS5, but with correct registration and the course of the vertical
current path 15 through every sublayer is indicated by the stitched line. With the
gate electrode layer SS1-SS5 provided on an underlying, not shown dielectric layer,
the total AND structure as shown in fig. 11 may have a thickness of 0.75 µm
and an area of about 100 µm2 (12·8 µm2). The
volume of the structure will hence be about 75 µm3. With conservative
spatial resolution this implies that about 10 000 logic gates of this kind may be
realized on an area of 1 mm2 and with a thickness well below 1 µm.
Correspondingly scaled the length of the current paths 9, 15 together becomes 60
µm.
Example 5 - AND gate with vertically stacked CMOS circuits
A reduction of the current path length and a significant
simplification of the structure of the AND gate may be achieved by stacking the
MOSFET structures vertically as shown in fig. 12. Again the same reference numbers
as in figs. 10 and 11 are used, and it will be seen that the vertical AND gate structure
exploits the fact that the gate electrodes g1 and g3 of the
transistors Q1, Q3 are at the same common potential, the gate
electrodes g2 and g4 in Q2, Q4 on another
common potential and the gate electrodes g5 and g5 in Q3,
Q6 on a third common potential. Hence the transistors Q1-Q6
are implemented as CMOS circuits in a pairwise back-to-back configuration by common
gate electrode g1,g3; g2,g4; g5,g6
for the corresponding MOSFET structures Q1,Q3; Q2,Q4;
Q5,Q6. Each CMOS circuit is provided on an isolating layer
which in fig. 12 is located below Q3, between Q1 and Q4
and between Q2 and Q5 in each of the MOSFET structures. The
gate electrodes g are also, of course, isolated from the active semiconductor material
b by not explicitly denoted isolating layers which comprise the respective gate
isolators. The horizontal current paths in figs. 10 and 11 are now substantially
replaced by vertical current paths which extend through the layers and provide the
same connection as shown in the equivalent circuit in fig. 9. Particularly the current
path 15 is shown which also is realized vertically in the configuration in fig.
10 and, as will be seen, as before connects the gate electrodes g5,g6
On Q5, Q6 with the connection between the drain electrodes
d2,d3 on Q2, Q3 and the drain electrode
d1 on Q1.
The vertical AND gate structure in fig. 12 including the
substrate 1 is generated by a total of 24 sublayers, of which 6 relatively thick
isolating layers form the gate isolators and three corresponding thick isolating
layers isolate the paired combinations of MOSFET structures mutually. With the same
dimensions as indicated in connection with the description of fig. 11 the whole
stacked layer configuration in fig. 12 hence will have a thickness of about 3.0
µm and be provided on an area of 16 µm2. The total volume thus
becomes less than 50 µm3, a reduction of the volume of 1/3 relative
to the configuration in fig. 11. Most important is, however, the current paths which
in the configuration in fig. 11 from the indicated dimensions will have a length
of 52 µm, may in the configuration in fig. 12 well be about 15 µm in an
optimal embodiment, which implies a reduction of about 70%. In this connection it
shall particularly be taken in regard that fig. 12 is schematic and that the vertical
current paths are mutually displaced in the horizontal and that the vertical current
paths are mutually displaced in the horizontal plane in order to appear more clearly.
They may, however, lie in the same plane, parallel to one of the side surfaces of
the structure.
Within the scope of today's thin-film technology and using
technologies as mentioned above in order to create electrical conduction and/or
semiconducting structures in thin films by irradiation of convertible organic materials,
it is wholly possible to reduce the linear dimensions in the horizontal direction,
such that the component density may be increased by at least one order of magnitude.
This implies that the configuration in fig. 11 may realize about 105
logic gates of the kind shown on 1 mm2 and with a layer thickness well
below 1 µm, while the configuration in fig. 12 might realize about 6·105
gates on the same area with a somewhat better form factor, such that the increase
in the device density becomes about 33% relative to the device density of the configuration
in fig. 11.
The processing of single layers, i.e. the generating of
electrical conducting and/or semiconducting structures may after the converting
by means of electric fields has taken place and when it is performed as shown in
figs. 2a-f and fig. 3, include possible post-treatments and corrections, e.g. a
possible heat treatment before the separate layers are joined into a multilayer
structure and form a stacked circuit configuration.
For instance a heat treatment of single layers after the
conversion may be performed to control conducting and/or semiconducting properties,
e.g. conversion of monomer to oligomer or polymer, doping, crystallization etc.
Such processes are well-known and have a wide application and specific examples
shall hence not be given here. The heat treatment may e.g. be performed by means
of irradiation. Another possibility is to use the electric alternating fields. In
principle alternating fields may also be used to effect the field conversion of
EFCM and the power supply 23 shown in figs. 2a-f must then, of course, be an alternating
voltage source. In that connection it shall be remarked that a resistive material
which is subjected to an alternating field will be heated. By using an or voltage
field for generating a transition from a non-conducting to for instance a conducting
state a heating of the thus generated electrical conducting structure may take place
and a possible desired heat treatment may also take place in situ and simultaneously
with the conversion process.
By for instance using organic materials in the layers and
generating the electrical conducting and/or semiconducting structures with conversion
and by means of electric fields according to the present invention, there may be
obtained a far simpler and cheaper manufacturing of electronic devices than which
is possible with today's inorganic semiconductor technology. If a reel-to-reel arrangement
is used in the manufacture of circuits as shown in fig. 7, the production may take
place with high volume and high speed and without essential dimensional limitations.
With the joining of separate layers into a multilayer structure and forming of a
stacked configuration, the registration between the layers will, however, be critical
among other in order to ensure that vertical conducting structures in separate layers
register mutually and that for instance electrodes and active semiconductor materials
in semiconductor structures do the same. The requirement for registration accuracy
will be given by the pitch which may be realized in the manufacture of the electrical
conducting and/or semiconducting structures, but may practically also be realized
by using interferometric methods for control and positioning, optically recordable
marking, or mechanical or electrical nanotechnology. Such measures, however, fall
outside the scope of the present invention and are hence not discussed in greater
detail, but must be regarded as known to persons skilled in the art.
By using the method for generation according to the present
invention the protocol for a given circuit configuration in multilayer design may
be generated far from the manufacturing location of the circuit and transmitted
thereto for downloading to for instance a control device which controls the generation
of the physical circuit patterns in situ at the manufacturing location. A user may
hence thereby generate and produce circuits by tele-processing according to own
specifications solely by transmitting the necessary instructions and information.
The present invention may thus furnish the concept application- and customer-specific
circuit production with a radically new content.