JP3403136B2 - Method for manufacturing switching element, switching element and switching element array - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a switching element used for driving a flat panel display, a switching element and a switching element array.

[0002]

2. Description of the Related Art In a display device such as a liquid crystal display or an EL display, by selectively driving thin film transistors (TFTs) and pixel electrodes as switching elements arranged in a matrix on a substrate such as a glass substrate, A display pattern is formed on the screen.

For example, in an active matrix type liquid crystal display device, an array substrate on which TFTs, pixel electrodes and wirings for applying signals to these are formed and an opposite substrate having an opposite electrode are arranged so as to face each other, and a liquid crystal is placed between them. It has an enclosed structure.

Conventionally, a TFT having silicon as an active layer has been used as a switching element used in such a display device. However, in order to form a silicon thin film, C is used.
A VD process is required, which is a major factor in preventing manufacturing cost reduction.

Although a glass substrate is usually used as the substrate, the glass substrate is generally vulnerable to impact and easily cracked. Therefore, it has been proposed to use a polymer film as a substrate in order to deal with the cracking of the substrate and the weight reduction and flexibility of the display device.

However, since the polymer film is far inferior in heat resistance as compared with the glass substrate, it is difficult to manufacture a silicon TFT which requires a relatively high temperature process.

Therefore, a switching element using an organic semiconductor which can be formed by a low temperature and inexpensive process as an active layer is under study.

However, the carrier mobility of an organic semiconductor is equal to or less than that of amorphous silicon in many cases. Therefore, a sufficient ON current value cannot be obtained.
It is not sufficient to drive a current drive type display device such as an L display.

There is a static induction type transistor (SIT) as a switching element which can obtain a relatively good ON current value even at low mobility. This is a vertical transistor in which a normal TFT allows a current to flow in the sheet direction of the active layer, while a vertical transistor allows a current to flow in the film thickness direction.

FIG. 1 is a schematic sectional view showing the structure of the SIT. Generally, the SIT has a structure similar to a triode in which a sheet-shaped gate electrode 3 having many holes (hereinafter referred to as gate holes) is inserted between a pair of parallel plate electrodes composed of a source electrode 1 and a drain electrode 2. A semiconductor layer 4 is filled between the parallel plate electrodes and in the gate hole. When a voltage is applied to the gate electrode 3, a depletion layer is formed in the semiconductor layer 4 penetrating the gate hole, and the current can be controlled.

In SIT using an organic semiconductor as an active layer, it is necessary to efficiently control the current even in a thin depletion layer in order to sufficiently reduce the low drive voltage and the OFF current value.
Therefore, it is necessary to make the gate hole small. In other words, organic semiconductors generally have insufficient carrier mobility as compared with inorganic semiconductors, so that it is necessary to increase the dopant concentration in order to obtain a sufficient ON current value. When the dopant concentration is high, the depletion length of the depletion layer formed at the same voltage is small. Therefore, depending on the dopant concentration, in the case of SIT using an organic semiconductor for the active layer, the diameter of the gate hole is 1μ.
It is necessary to make it m or less.

However, the resolution of a relatively low-cost lithography process that is usually used when manufacturing a flat panel display such as a liquid crystal display is about several μm, and it is expensive to form a gate hole of 1 μm or less in the lithography process. turn into.

In SIT using an organic semiconductor as an active layer, it has been attempted to use a discontinuous aluminum film formed by thinly depositing aluminum as a gate electrode (Kudo et al. Synthetic Metal).
s 102 (1999) 900-903), the formed porous structure is not uniform, resulting in poor durability, and it is difficult to obtain good switching characteristics, and the porous structure of the gate electrode largely changes depending on vapor deposition conditions. Therefore, when forming a switching element array for a display that needs to be collectively formed on a large-area substrate, it is difficult to keep the characteristics of each element constant.

[0014]

As described above, in the SIT using an organic semiconductor which can be manufactured at a low temperature as an active layer,
Since a hole having a size necessary for reducing the drive voltage and the OFF current value is formed in the gate electrode, it is difficult to manufacture the gate electrode at a low cost in the lithography process. Further, in forming a discontinuous film by vapor deposition, it has been difficult to form a gate hole of a gate electrode uniformly and form a gate electrode having uniform switching characteristics and excellent durability.

According to the present invention, when manufacturing a SIT gate electrode using an organic semiconductor which can be manufactured at a low temperature as an active layer, a gate electrode having a sufficiently small gate hole and a uniform gate hole is formed, which has excellent durability. It is an object of the present invention to provide a method for manufacturing a SIT type switching element that can be easily obtained, can reduce the drive voltage and the OFF current value, and exhibits good switching characteristics.

Further, the present invention relates to a SIT type switching element using an organic semiconductor which can be manufactured at a low temperature as an active layer, having a gate electrode excellent in durability, and a switching element excellent in switching characteristics. It is an object of the present invention to provide a switching element array that has been used.

[0017]

According to the present invention, there is provided an electrode pair comprising a source electrode and a drain electrode, a sheet-like gate electrode inserted between the source electrode and the drain electrode and having a plurality of through holes, and the gate. In a method of manufacturing a switching element, comprising an electron-transporting or hole-transporting organic charge-transporting substance filled in voids between the through-holes of the electrodes and the electrode pair, the gate electrode constitutes the gate electrode. A first step of forming a gate electrode precursor film, which is a thin film made of a substance, and a thin film of a compound such as a block copolymer or a graft copolymer that forms a microphase-separated structure on the gate electrode precursor film. A second step of forming, a third step of forming the micro phase separation structure in the thin film of the copolymer, and a small amount of the formed micro phase separation structure. A fourth step of selectively removing at least one kind of phase to form a porous film, and using the porous film as an etching mask, the gate electrode precursor film is etched to form a gate electrode having a plurality of holes. It is a manufacturing method of a switching element characterized by being manufactured by performing a fifth step.

Further, the present invention is a switching element comprising an electrode pair consisting of a source electrode and a drain electrode, and a gate electrode inserted between the source electrode and the drain electrode without contacting the electrode pair. The gate electrode is formed with a plurality of through holes having one surface facing the source electrode and the other surface facing the drain electrode, and a plurality of through holes each having an opening on each surface. It has a plurality of regions forming a dot pattern forming a triangular lattice at least partially between the contact openings, and has an electron transporting property or a hole transporting property in the through hole of the gate electrode and in the space between the electrode pair. The switching element is characterized by being filled with the organic charge transporting substance.

Further, the present invention is a switching element array for a display device comprising the above switching element.

That is, in the manufacturing method of the present invention,
In manufacturing a SIT type switching element using an organic semiconductor as an active layer, a micro phase separation structure using a copolymer that generates a micro phase separation structure on a gate electrode precursor film is used in a gate electrode manufacturing process. Forming a porous film by selectively removing at least one phase of the micro phase separation structure, and further etching the gate electrode precursor film by using the porous film as an etching mask to form a plurality of holes. A gate electrode having is formed.

According to the manufacturing method of the present invention in which the gate hole is formed by using the copolymer which forms the micro phase separation structure, the application of the copolymer which forms the micro phase separation structure is required. Therefore, the gate hole is sufficiently small and a uniform hole can be provided for a gate electrode with a constant film thickness by only the simple steps of forming a micro phase separation structure such as drying and heating and etching. Thus, it is possible to obtain a gate electrode that is inexpensive and has higher durability than the discontinuous film formation by vapor deposition.

Therefore, according to the manufacturing method of the present invention,
In a SIT type switching element using an organic semiconductor which can be manufactured at a low temperature as an active layer, it is possible to easily obtain an SIT type switching element which has a reduced OFF current value at a low driving voltage and exhibits good switching characteristics. You can

Further, for example, in the switching element of the present invention which can be manufactured by the manufacturing method of the switching element of the present invention, the opening of the gate hole formed in the gate electrode is at least partially between the closest openings. It has a plurality of areas that form a dot pattern that forms a triangular lattice. In this region, the openings are regularly arranged, and a gate electrode having better switching characteristics and higher durability than a discontinuous film formed by vapor deposition can be obtained.

Therefore, according to the switching element of the present invention, it is possible to obtain an SIT type switching element exhibiting excellent switching characteristics in the SIT type switching element using an organic semiconductor which can be manufactured at a low temperature as an active layer. .

Further, by applying such a switching element to a switching element array, a wide range of applications to various flat panel displays and the like are expected, and its industrial value is extremely large.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION The switching element according to the present invention relates to a static induction transistor (SIT). SIT is mainly classified into two types, a Schottky gate type and an insulated gate type. Hereinafter, these two types will be described in order. 1. Schottky gate type Schottky gate type SIT is characterized in that the gate electrode and the charge transporting material are in Schottky junction.

Schottky gate type SI according to the present invention
A typical device structure of T is shown in FIG.

The Schottky gate type SIT has an electrode pair consisting of a source electrode 1 and a drain electrode 2, and a porous sheet-shaped gate electrode 3 is inserted between the electrodes without making contact with these electrode pairs. . A charge-transporting substance 4 is filled in the space between the electrodes and the holes provided in the gate electrode 3. The gate electrode 3 is in Schottky contact with the charge transporting material 4.

The charge-transporting substance 4 is composed of an organic hole-conducting substance or an electron-conducting substance, and specifically, an organic semiconductor doped with p-type or n-type is used.

The organic semiconductor includes low molecular weight compounds and high molecular weight compounds, and the low molecular weight compounds are exemplified below.

That is, a phthalocyanine derivative, a naphthalocyanine derivative, an azo compound derivative, a perylene derivative, an indigo derivative, a quinacridone derivative, a polycyclic quinone derivative such as anthraquinones, a cyanine derivative, a fullerene derivative, or Indole,
Nitrogen-containing cyclic compound derivatives such as carbazole, oxazole, inoxazole, thiazole, imidazole, pyrazole, oxaadiazole, pyrazoline, thiathiazole and triazole, hydrazine derivatives, triphenylamine derivatives, triphenylmethane derivatives, stilbenes, anthraquinonediene Examples thereof include quinone compound derivatives such as phenoquinone, and polycyclic aromatic compound derivatives such as anthracene, pentacene, pyrene, phenanthrene and coronene.

It is preferable that these low molecular weight compounds are in an amorphous state, and it is preferable that the low molecular weight compound has a stable starburst type molecular shape.

As the above-mentioned polymer compound, the structure of the above-mentioned low-molecular compound is polyethylene chain, polysiloxane chain,
Used are those in the main chain of ordinary electrically inactive polymer chains such as polyether chains, polyester chains, polyamide chains and polyimide chains, or those pendantly bonded as side chains.

Further, as the polymer compound, the conjugated polymer compounds as exemplified below can be favorably used.

That is, an aromatic conjugated polymer such as polyparaphenylene, an aliphatic conjugated polymer such as polyacetylene, a heterocyclic conjugated polymer having a polypyrrole or polythiophene ratio, and a hetero-containing polymer such as polyaniline or polyphenylene sulfide. Atomic conjugated polymers, such as poly (phenylene vinylene), poly (arylene vinylene), poly (thienylene vinylene), and other conjugated conjugated polymers having a structure in which constituent units of the above conjugated polymers are alternately bonded A carbon-based conjugated polymer is preferably used.

Further, oligosilanes such as polysilanes, disilanylenearylene polymers, (disilanylene) ethenylene polymers, and (disilanylene) ethynylene polymers such as disilanylene-carbon conjugated polymer structures and carbon-based conjugated properties Polymers in which the structures are alternately linked are preferably used.

Such a main chain type conjugated polymer chain is more preferable than the above pendant type because it has excellent carrier transport properties such as carrier mobility.

Besides, polymer chains made of inorganic elements such as phosphorus and nitrogen may be used.

Further, polymers in which an aromatic ligand is coordinated with a polymer chain such as phthalocyanate polysiloxane may be used.

Further, a ladder-like polymer obtained by heat-treating perylenes such as perylenetetracarboxylic acid for condensation may be used. Further, a ladder type polymer obtained by heat-treating a polyethylene derivative having a cyano group such as polyacrylonitrile may be used.

Further, a composite material in which an organic compound is intercalated in perovskites may be used.

The material of the source electrode 1 and the drain electrode 2 is not particularly limited as long as it has sufficient conductivity, and gold,
Metals such as silver, copper, platinum, nickel, tungsten, aluminum and alloys thereof, metal oxides such as ITO, fluorine-doped varnish and vanadium oxide,
Graphite, n-type or p-type doped diamond, silicon, compound semiconductors, or organic conductive materials containing a conjugated polymer compound such as polyaniline, polythiophene, and polypyrrole are used.

The shape of the source electrode 1 and the drain electrode 2 is not particularly limited to a sheet shape, a mesh shape, a porous shape, a linear shape, a dot shape, a comb shape, etc., but as shown in FIG. It is preferably a flat plate electrode.

The thickness of the source electrode 1 and the drain electrode 2 is not particularly limited, but it is desired that the thickness is set to 5 to 2000 nm, preferably 10 to 500 nm, and further 20 to 200 nm.

In order to increase the amount of current flowing between the source and drain, it is usually preferable that the source electrode 1 and the drain electrode 2 are in ohmic contact with the charge transporting substance 4.

The gate electrode 3 may be flat, curved, or cylindrical as long as it has a sheet shape.

The thickness of the gate electrode 3 is not particularly limited, but it is desired that the gate electrode 3 is set at 5 to 500 nm, preferably 10 to 100 nm, and further 20 to 50 nm. If it is too thick, the distance between the source electrode 1 and the drain electrode 2 is increased, and the internal resistance of the device is increased. If it is too thin, it becomes difficult to form a uniform continuous film, and the sheet resistance of the gate electrode 3 increases to deteriorate the voltage-current characteristics of the device. Moreover, the OFF current value also increases.

One side of the gate electrode 3 is the source electrode 1
On the other hand, the other surface faces the drain electrode 2, and a plurality of through holes each having one opening are formed on each surface.

The average radius of gyration of the opening is 10 to 1000 n.
It is desirable that it is m.

The thickness is more preferably 20 to 200 nm, further preferably 30 to 50 nm. If it is too large, the OFF current value increases or the drive voltage increases. On the other hand, if it is too small, the O applied to the applied voltage of the gate electrode
The change in the N current value becomes too sensitive, making control difficult.

The aperture ratio of the opening (total area of the opening / total area of the region in which the through holes are entirely formed × 100) is 10 to 9
It is desirable to set in the range of 5%, and more desirably 20 to 80%. If the aperture ratio is too small, the internal resistance of the device will increase. Conversely, if the aperture ratio is too large, the sheet resistance of the gate electrode will increase.

FIG. 2 shows a partial plan view of the gate electrode according to the present invention. The gate electrode has an opening 8. The gate electrode has a region 9 in which the openings 8 form a dot-like pattern forming a triangular lattice at least partially between the closest openings, and a plurality of the regions are formed.

Furthermore, it is preferable that the orientation axis 10 in the dot pattern forming the triangular lattice of each area 9 is different in direction from the same orientation axis 10 in the adjacent area 9.

Generally, in SIT, it is easier for the potential distribution in the plane of the gate electrode to be uniform and the electric field concentration tends to occur when the openings are uniformly arranged in a triangular lattice whose alignment axes are aligned over the entire gate electrode. It is hard to cause element destruction. In addition, the source
The value of the current flowing between the drains can also be changed sharply.

However, when the switching elements are arrayed and used as a switching element array for a display, the arrangement of such openings is not appropriate. This is because, when switching elements are arranged in an array, variations in characteristics are likely to occur among the switching elements. Therefore, when the current value between the source and drain changes too sharply at a specific gate voltage, even if the same voltage is applied, the current value flowing between the source and drain of each element will differ greatly, resulting in a uniform display screen. It becomes difficult to maintain sex.

In order to prevent this, it is better to reduce the responsiveness of the source-drain current to the gate voltage to some extent. If the regularity of the arrangement of the openings is broken, the way the voltage is applied in the plane of the gate electrode becomes non-uniform, and the responsiveness deteriorates. However, if it is made too irregular, responsiveness will be reduced more than necessary, and
Element breakdown due to electric field concentration is also likely to occur.

In particular, the radius of gyration of the opening is 0.5 to 1 μm.
In the case of about m, if the triangular lattice pattern is uniform over the entire surface of the gate electrode, interference with visible light is likely to occur. When such an array of switching elements is used in a display, if the gate electrode is seen through the display surface, interference fringes, moire patterns, etc. are likely to occur on the display surface, and the image quality is likely to deteriorate. By locally shifting the alignment axis as in the switching element of the present invention, the occurrence of such interference fringes and moire patterns can be suppressed.

The alignment of the openings formed in the gate electrode 3 of one switching element is from 2 to 10 million, preferably from 100 to 100,000, and more preferably from 100 to 10,000. It is desirable that the region is divided into regions having different orientation axes and directions. The number of openings forming one region is preferably 5 or more, and 100 or more.
The number is preferably 0 or less, more preferably 500 or less, and desirably 100 or less. Too few, localized openings,
If the structure is unevenly distributed, electric field concentration is likely to occur, which is not good. If there are too many, problems such as the above-mentioned interference effect are likely to appear.

The ON / OFF current ratio may be improved if the source electrode 1 and the gate electrode 3 are installed as close to each other as possible. It is preferable that the distance between the source electrode 1 and the gate electrode 3 is smaller than the depletion length in the layer made of the charge transporting substance formed at the driving voltage of the device. Alternatively, it is desired that the distance between the source electrode 1 and the gate electrode 3 is smaller than the average radius of gyration of the opening of the gate electrode 3.

In the Schottky gate type SIT,
The gate electrode 3 is in Schottky contact with the charge transport material 4. Therefore, as the material, when the charge transporting substance 4 is a p-type semiconductor, a substance having a small work function is preferable, and for example, aluminum or its alloy is preferably used. When the charge transporting substance 4 is an n-type semiconductor, a substance having a large work function is preferable, and gold, platinum, ITO, fluorine-doped tin oxide or the like is suitable.

The Schottky gate type SIT may have a structure in which the gate electrode is supported by the insulating layer. Figure 3
A device structure of a Schottky gate type SIT having a structure in which a gate electrode is supported by an insulating layer is shown in (a) and (b). The insulating layer 5 supports the gate electrode 3 from one surface of the gate electrode 3 in FIG. 3A and from both surfaces of the gate electrode 3 in FIG. Such a structure is preferable because it is not necessary to pattern the gate electrode on the latent layer which is easily modified, as described later. In general, a charge transporting material has a high dielectric constant and easily increases the capacitance of the switching element. Therefore, it is also desirable to reduce the capacitance of the switching element.

The insulating layer 5 supporting the gate electrode 3 is preferably made of an insulating material having a low dielectric constant in order to reduce the electrostatic capacitance of the switching element. As the insulating substance, for example, a polymer material such as polyimide or an inorganic material such as SiO is used. Among them, polyimides,
Polyimide or Si with pores of nanometer order
A porous film such as O is preferable. 2. Insulated gate type The insulated gate type SIT has the same structure as the Schottky gate type SIT except that the gate electrode and the charge transporting substance are insulated by the insulating layer.

A typical device structure of the insulated gate SIT according to the present invention is shown in FIG. The insulated gate SIT includes an electrode pair composed of a source electrode 1 and a drain electrode 2, and a porous sheet-shaped gate electrode 3 is inserted between the electrodes without contacting these electrode pairs. A charge transporting material 4 is provided between the electrodes and in the holes provided in the gate electrode 3.
Is filled. The surface of the gate electrode 3 is covered with a gate insulating layer 5 ′ so as to be insulated from the charge transporting substance 4.

As the charge transporting substance 4, the same substance as the Schottky gate type SIT can be used.

Material of the source electrode 1 and the drain electrode 2,
The same shape and thickness as those of the Schottky gate type SIT can be used.

The shape and thickness of the gate electrode 3, and the configuration of the through hole formed in the gate electrode and the opening thereof can be the same as those of the Schottky gate type SIT.

The ON / OFF current ratio may be improved if the source electrode 1 and the gate electrode 3 are installed as close to each other as possible. It is preferable that the distance between the source electrode 1 and the gate electrode 3 is smaller than the depletion length in the layer made of the charge transporting substance formed at the driving voltage of the device. Alternatively, it is desired that the distance between the source electrode 1 and the gate electrode 3 is smaller than the average radius of gyration of the opening of the gate electrode 3.

Unlike the Schottky gate type, the material of the gate electrode 3 is not particularly limited as long as it has sufficient conductivity, and gold, silver, steel, platinum, nickel, tungsten, aluminum and these materials can be used. Metals such as alloys, IT
O, Fluorine-doped tin oxide, metal oxides such as vanadium oxide, graphite, n-type or p-type doped diamond, silicon or compound semiconductors, or polyaniline, polythiophene, polypyrrole, etc. An organic conductive material containing a polymer compound or the like is used.

The gate insulating layer 5'is provided to insulate the gate electrode 3 from the charge transporting substance 4, and the material thereof is not particularly limited as long as it is insulative, and an organic polymer film such as polyimide or the like may be used. , Silicon oxide, and metal oxides such as alumina and tantalum oxide are preferable. The oxide film may be newly formed on the porous gate electrode surface, or the gate electrode may be formed of aluminum, tantalum, or the like, and the surface of the gate electrode may be oxidized to form a surface oxide layer. It is more preferable that these gate insulating layers have a high dielectric constant in order to reduce the driving voltage.

The thickness of the gate insulating layer 5'is not particularly limited, but is 10 to 100 nm, more preferably 20 to 50 nm.
It may be set to nm. If it is too thin, it is difficult to have a sufficient insulating function, and if it is too thick, problems such as an increase in driving voltage occur.

Further, like the Schottky gate type SIT,
The insulated gate SIT may have a structure in which the gate electrode is supported by an insulating layer. FIGS. 5A and 5B show an insulated gate SIT device structure having a structure in which a gate electrode is supported by an insulating layer. The insulating layer 5 supports the gate electrode 3 from one surface of the gate electrode 3 in FIG. 5A and from both surfaces of the gate electrode 3 in FIG. 5B. Such a structure is preferable because the electrostatic capacitance of the switching element can be reduced and deterioration of the charge transporting substance can be prevented in the manufacturing process.

At this time, the insulating layer 5 supporting the gate electrode 3 and the drain electrode 1 or the gate electrode 3 sandwiched between the source electrodes 2 is formed of an insulating material having a low dielectric constant,
The gate insulating layer 5'on the inner surface of the gate hole of the gate electrode 3 is preferably formed of an insulating material having a high dielectric constant because both the driving voltage and the capacitance of the device can be reduced.

In any of the Schottky gate type element and the insulated gate type element described above, the charge transport layer does not have to be a single layer and may have a laminated structure composed of a plurality of layers. In addition, at least one of the laminated layers may be formed of an EL light emitting layer. By incorporating the light emitting layer, an EL element and a switching element can be laminated and integrated. In this case, at least one of the source electrode and the drain electrode is preferably a transparent electrode such as ITO.

Next, a method of manufacturing the switching element of the present invention will be described.

The manufacturing method of the switching element of the present invention is as follows.
It is characterized by the method of forming the opening of the gate electrode. The opening of the gate electrode according to the present invention utilizes a micro phase separation phenomenon that self-develops in a compound such as a block copolymer or a graft copolymer, and masks the micro phase separation structure formed by the compound. Is formed by patterning the gate electrode.

In the present invention, the microphase separation means the intramolecular phase separation of the block copolymer. On the other hand, intermolecular phase separation of a polymer blend composed of two kinds of polymers is called macro phase separation. In macro phase separation, the two polymer chains can be completely separated, and finally the two phases are completely separated. Moreover, since the scale of fluctuation occurrence is about 1 μm,
It is difficult to form a structure smaller than the regular μm order.
On the other hand, in the micro phase separation, since two types of polymer chains are bonded, the size of the unit cell does not become larger than the size of the molecular chain, and a regular nm-order structure can be formed.

Each step will be specifically described below.

In the first step, first, a thin film (hereinafter referred to as a gate precursor film) of a material forming a gate electrode is formed.

In the second step, a thin film (hereinafter referred to as a pattern forming film) of a compound that forms a micro phase separation structure such as a block copolymer or a graft copolymer is formed on the gate precursor film.

In the third step, the pattern forming film is heated as necessary to form a micro phase separation structure in the pattern forming film.

In the fourth step, at least one phase of the microphase-separated structure is selectively removed to turn the pattern forming film into a porous film.

In the fifth step, the gate precursor film is etched by using the porous pattern forming film as an etching mask. As a result, an opening pattern in which the micro phase separation structure generated in the pattern forming film is transferred is formed in the precursor film to form a gate electrode.

By performing the above first to fifth steps, the opening can be formed in the gate electrode.

Examples of the compound that forms the microphase-separated structure used as the pattern forming film include a block copolymer and a graft copolymer. The microphase-separated structure formed by the block copolymer or the graft copolymer often exhibits a pattern shape in which a plurality of regions having a regular array pattern are aggregated. The size and shape of such a pattern can be freely designed to some extent by appropriately selecting the molecular weight and the copolymerization ratio of the block copolymer or the graft copolymer.

In the present invention, the block copolymer or the graft copolymer may be used alone or a homopolymer may be mixed and used as the pattern forming film. When only the copolymer is used, a pattern having a period of about 10 to several hundreds nm can be obtained. Furthermore, the size of the domain formed by the block chains is expanded to about 1 μm by adding a polymer having a good affinity for each block chain constituting the copolymer, often a homopolymer of each block chain. It is possible. However, if too much homopolymer is mixed, the homogeneity and regularity of the domain size and arrangement are easily disturbed. Therefore, the mixing ratio of the homopolymer is 50% or less of the block copolymer or graft copolymer by weight ratio. It is preferably 10% or less.

In the switching element of the present invention, the pattern of the opening of the gate electrode is preferably a dot pattern in terms of the current-voltage characteristics of the element. To form the dot pattern, sea islands are formed in the pattern forming film. It suffices to generate a micro-phase-separated structure in the shape of. In order to form the sea-island structure, it is preferable to set the volume fraction of the sea phase to about 30% or less.

As the type of block copolymer or graft copolymer used in the method for producing a switching element of the present invention, a micro phase separation structure can be formed, and a desired one phase can be formed while maintaining the micro phase separation structure. There is no particular limitation as long as it can be removed to make it porous, but the following three types can be preferably used.

(A) At least 2 constituting the copolymer
The dry etching rate ratio of one kind of polymer block chain is 1.
A block copolymer or graft copolymer having 3 or more is used. The pattern forming film made of such a block copolymer or graft copolymer can be used to make the pattern forming film porous in the fourth step by dry etching selective and preferably highly anisotropic.

(B) At least 1 constituting the copolymer
A block copolymer or a graft copolymer is used in which the main chain of the polymer block chain is a decomposable block chain that is decomposed by energy beam irradiation. A pattern forming film made of such a block copolymer or a graft copolymer is used, and in the fourth step, the phase made of the decomposable block chain is decomposed and removed by irradiation with energy rays to make the pattern forming film porous. can do.

(C) A block copolymer or graft copolymer comprising at least two polymer block chains of a heat resistant block chain and a pyrolytic block chain is used. The pattern forming film made of such a block copolymer or graft copolymer is used, and in the fourth step, the phase made of the thermally decomposable block chain is selectively removed by heat treatment to make the pattern forming film porous. can do.

Specific examples of the block copolymer or graft copolymer of (a) include an aromatic ring-containing polymer chain as a block chain having etching resistance, and an acrylic polymer chain or polyether as a block chain which is easily etched. A block copolymer or a graft copolymer having a chain or a polysilane chain is preferably used.

The aromatic ring-containing polymer chain is, for example, a polymer chain obtained by polymerizing at least one kind of monomer selected from vinylnaphthalene, styrene or derivatives thereof, and the acrylic polymer chain is, for example, polyacrylic acid or polyacrylic acid. A polymer chain obtained by polymerizing at least one monomer selected from acrylic acid, methacrylic acid, crotonic acid or derivatives thereof such as methyl methacrylate and poly t-butyl methacrylate is used. The polyether chain is preferably a polyalkylene oxide chain such as polyethylene oxide or polypropylene oxide. The polysilane chain is preferably a dialkylpolysilane derivative such as polydibutylsilane.

Specific examples of the combination of block chains in the block copolymer or graft copolymer are as follows. Polystyrene chain +
Polymethylmethacrylate chain, polystyrene chain + polyacrylic acid chain, polystyrene chain + polyethyleneoxide chain, polystyrene chain + polypropyleneoxide chain, polystyrene chain + polyphenylmethylsilane chain, polystyrene chain + polydibutylsilane chain, polyvinylnaphthalene chain + polymethyl Methacrylate chains, polyvinylnaphthalene chains and polyacrylic acid chains, polyvinylnaphthalene chains + polyethylene oxide chains, polyvinylnaphthalene chains + polypropylene oxide chains, polyvinylnaphthalene chains + polyphenylmethylsilane chains, polyvinylnaphthalene chains + polydibutylsilane chains and the like.

As a dry etching gas for dry etching in the fourth step using the copolymer shown in (a), various etching gases such as Ar, O ₂ , CF ₄ and H ₂ are used. At this time, it is desirable to perform the etching under the condition that anisotropic etching is performed. When O ₂ gas is used, a silicon-based polymer such as polysilanes or polysiloxanes or a silicon-containing polymer such as poly (trimethylsilylstyrene) is used as a polymer chain that is difficult to be etched, and is a non-silicon-containing carbon-based polymer. It is preferably combined with a polymer chain that is easily etched, such as an acrylic polymer chain or a polyether chain.

As the energy rays used for decomposing / removing in the fourth step using the copolymer shown in (b), electromagnetic waves such as visible rays, ultraviolet rays, X-rays, electron rays (β rays) or particle rays are used. Used. Ultraviolet rays or electron beams are mainly used in practice. Among them, the electron beam is most preferable in terms of versatility.

As the ultraviolet ray source, a high pressure mercury lamp, an ultra high pressure mercury lamp, a low pressure mercury lamp, a carbon arc, a black light,
You can use a light source such as a metal halide lamp.

As the electron beam source, various electron beam accelerators such as Cockloft-Walton type, Van de Graft type, resonance transformer type, insulating core transformer type, linear type, dynamitron type and high frequency type are used. ~ 1000 Ke
Those which irradiate with electrons having an energy of V, preferably 100 to 30 KeV can be used. Usually, the irradiation dose is about 0.5 to 30 Mrad.

The block copolymer or graft copolymer of (b) has a decomposable block chain in which the main chain cleavage reaction proceeds by the above energy rays. The remaining block chain is preferably one in which the main chain is three-dimensionally crosslinked by irradiation with energy rays.

Specifically, for example, as a block chain in which a main chain cleavage reaction is caused by irradiation with ultraviolet rays, Norri can be obtained by irradiating with light such as poly (phenylisopropenyl ketone).
A substance that causes a shType1 reaction to cause a main chain cleavage reaction may be used. Further, polysilane chains such as polydibutylsilane can also be preferably used.

Examples of the block chain that causes the main chain cleavage reaction by electron beam (β-ray) irradiation include polyolefins such as polypropylene and polyisobutylene, poly-α-methylstyrenes, polymethacrylic acid such as polymethacrylic acid and polymethylmethacrylate. Acid esters, polymethacrylamides, polybutene-1-sulfone, polystyrene fulphone, polyolefensulphones such as poly-2-butylene sulphone, polymethylisopropenyl ketone, polymethacrylonitrile and the like are used. Particularly, polyhexafluorobutyl methacrylate, polytetrafluoropropyl methacrylate, which is a polymethacrylic acid ester into which fluorine is introduced, and polytrifluoroethyl-α-chloro in which the methyl group at the α-position of the polymethacrylic acid ester is replaced with chlorine. Acrylate is also good.

Polystyrene, polyacrylic acid, and the like are block chains that are three-dimensionally crosslinked by electron beam (β-ray) irradiation.
Polyacrylic acid ester such as polymethyl acrylate, polyacrylamide, polymethyl vinyl ketone, or block chain having side chain such as epoxy group such as glycidyl group, double bond, or triple bond, which has a structure easily cross-linked by electron beam irradiation. Is mentioned. A vinylidene fluoride resin such as a vinylidene fluoride homopolymer or a copolymer of vinylidene fluoride and propylene hexafluoride is also preferable.

As the decomposable block chain which causes a main chain cleavage reaction and the crosslinkable block chain which causes a crosslinking reaction upon irradiation with X-rays, basically the same ones as those for electron beam can be used. Furthermore, as a degradable block chain,
Metal salts such as Ti of polymethacrylic acid, polydimethylmethylene malonate, polychloroacetaldehyde and the like can also be used. As the crosslinkable block chain, for example, a metal salt of polyacrylic acid such as Ba, Pb, or Nd, a halogen-containing polyvinyl ether such as chloroethyl vinyl ether, or the like can be used.

After irradiation with energy rays, the decomposed block chains are removed by dry etching, wet etching such as solvent cleaning, or a method of volatilizing the decomposed products by heat treatment.

The copolymer used in the block copolymer (c) or the graft copolymer (c) is composed of a heat resistant block chain and a heat decomposable block chain.

As the heat resistant block chain, a polysilane chain, a polysiloxane chain, a polyacrylonitrile chain, a polymethacrylonitrile chain, a polyimide chain, a polyaniline derivative chain, a polyparaphenylene derivative chain composed of Si-Si bond chains, There is a polycyclohexadiene derivative represented by the chemical formula 1.

[Chemical 1] (Wherein R is a substituted or unsubstituted alkyl group, aryl group or aralkyl group) Among them, a polyacrylonitrile chain or a polymethacrylonitrile chain capable of living polymerization and capable of forming a good block copolymer having a narrow molecular weight distribution. Ronitrile chain, PPP
A precursor polymer chain obtained by polymerizing a monomer is preferable.

Further, as the heat resistant block chain, a polymer chain having a site which forms a heat resistant molecular structure in the side chain or main chain by heat crosslinking can also be favorably used. For example, those having a perylene skeleton in the side chain or the main chain can be preferably used. In addition, the side chain or the main chain has POSS (Polyhedral Oligom).
A polymer chain having a siloxane cluster such as eric silsesquioxane (polysiloxane T ₈ cube) in the main chain or in the side chain may be used, and for example, a methacrylate T represented by the following chemical formula 2 may be used.
_It is preferable to polymerize ₈ cubes.

[Chemical 2] (R represents H or a substituted or unsubstituted alkyl group, aryl group, aralkyl group, for example, methyl group, ethyl group, butyl group, isopropyl group, phenyl group, etc.) Besides the carbon-based polymer, a polysilane chain may be used as the block or graft copolymer polymer. Any polysilane chain may be used as long as it contains a polysilane structure having a repeating unit represented by the following chemical formula 3 in at least a part thereof.

[Chemical 3] (However, R1, R2, R3, and R4 are the same or different and each represent a substituted or unsubstituted alkyl group, aryl group, or aralkyl group having 1 to 20 carbon atoms.) The polysilane chain may be a homopolymer or a copolymer. It may have a structure in which one or more polysilanes are bonded to each other through an oxygen atom, a nitrogen atom, an aliphatic group, or an aromatic group.

Specific examples of such a polysilane chain include, for example, poly (methylphenylsilane), poly (diphenylsilane), poly (methylchloromethylphenylsilane), poly (dihexylsilane), poly (propylmethylsilane), poly ( Dibutylsilane), poly (methylsilane), poly (phenylsilane) and the like, and random or block copolymers thereof.

Further, since the polysilane chain is a silicon-based polymer chain, it is easy to increase the etching selection ratio with respect to a general carbon-based polymer chain, and the pattern transfer layer is formed in the pattern transfer step described later. When the carbon-based polymer is used, it is easy to transfer the pattern to the pattern transfer layer, which enables good pattern formation.

The polysilane chain is photooxidized by irradiating it with ultraviolet rays in the air or in an oxygen-containing atmosphere, and the main chain is cleaved and oxygen is inserted to form a siloxane bond. It is possible to drastically change the etching characteristics of the polysilane phase by this photo-oxidation. In addition, a heat treatment after photooxidation causes a crosslinking reaction mainly composed of siloxane bonds to change into a structure similar to SiO ₂ , so that heat resistance can be improved. In particular, phenylmethylpolysilane is preferable because it easily causes a cross-linking reaction by ultraviolet irradiation.

As the silicon block chain, a polysiloxane chain other than the polysilane chain may be used. It is also possible to synthesize a polymer having a small molecular weight distribution from a cyclic oligosiloxane having a polysiloxane chain by a living polymerization method. As the polysiloxane chain, poly (di-i-
Propoxysiloxane) and poly (di-t-butoxysiloxane) having an alkoxyl group in the side chain are preferable. Such a polysiloxane chain having an alkoxyl group on its side chain is preferable, since the alkoxyl groups are three-dimensionally crosslinked by a siloxane bond by heat treatment in the presence of an acid catalyst or the like, and heat resistance and mechanical strength are improved.

Further, a silicon-containing polymer such as poly (pentamethyldisilirylstyrene) may be used, and these may preferably be ozone-oxidized or / and irradiated with ultraviolet rays to have a heat-resistant structure similar to silicon oxycarbite.

Examples of the thermally decomposable block chain include polyethers such as polyethylene oxide and polypropylene oxide, α-methylstyrenes, acrylic resins such as polyacrylic acid ester and polymethacrylic acid ester, and polyphthalaldehydes. Used. Among them, polyethylene oxide, polypropylene oxide, α
-Methylstyrene, acrylic resins and the like are excellent because they can synthesize block chains having a narrow molecular weight distribution by living polymerization.

Specific examples of the combination of the heat resistant block chain and the heat decomposable block chain include polyacrylonitrile chain + polyethylene oxide chain, polyacrylonitrile chain +
Polypropylene oxide chain, polymethacrylonitrile chain + polyethylene oxide chain, polymethacrylonitrile chain + polypropylene oxide chain, polymethylphenylsilane chain + polystyrene chain, polymethylphenylsilane chain +
Examples include α-polystyrene chain, polymethylphenylsilane chain + polymethylmethacrylate, polymethylphenylresilane chain + polyethylene oxide chain. (In each case, the former shows a heat-resistant block chain, and the latter shows a thermally decomposable block chain.) Through the above first to fifth steps, the opening can be provided in the gate electrode. Further, a method of manufacturing a switching element using the above technique will be described.

Although the substrate side is used as the source electrode in the following steps, it goes without saying that the drain electrode may be used instead.

First, FIG. 6 is a sectional view showing the outline of the method of manufacturing the Schottky gate type SIT.

Step (1) Source Electrode Forming The source electrode 1 is formed on the substrate 6, and a wiring pattern is patterned on the source electrode 1 if necessary. IT
O film etc. is formed by the sputtering method, or P film is formed.
A metal film of t, Au, Pd, Ag, Cu, Ni, Co, In, W or the like is formed by a method such as a vapor deposition method, a sputtering method, or plating. Alternatively, a conductive polymer film such as polyaniline, polypyrrole, or polythiophene may be formed by a method such as coating or electric field polymerization.

Step (2) Formation of Insulating Layer An insulating layer 5 is formed on the source electrode 1. An SiO film or the like is formed by a sputtering method, a CVD method, an LPD method, or the like, or a polyimide film is formed by a coating method, an evaporation method, an electrodeposition method, or the like.

Step (3) Formation of Gate Electrode Precursor Film A gate electrode precursor film 3 is formed on the insulating layer 5. When a p-type organic conjugated polymer material or the like is used as the charge transporting substance, a metal film having a small work function such as aluminum is formed by a vapor deposition method or the like. This step corresponds to the first step of the manufacturing method of the present invention.

Step (4) Patterning of Gate Holes by Forming Pattern Film A pattern forming film 7 is formed on the gate electrode precursor film 3 by a spin coating method, a dipping method, a coating method such as an inkjet method, or the like. If necessary, a heat treatment or the like is performed to form a phase separation structure in the pattern forming film 7. The gate electrode film 3 and the insulating layer 5 are patterned using the pattern forming film 7 as an etching mask to form a gate hole. At the same time, if necessary, the gate electrode 3 is patterned into a desired wiring pattern. After patterning, the pattern forming film 7 is lifted off. (This step corresponds to the second to fifth steps according to the present invention) Step (5) Formation of charge transporting material The organic charge transporting material 4 is formed by a method such as CVD, vapor deposition, coating, plating, or LPD method. Form. At this time, the inside of the gate hole is also filled.

Step (6) Formation of Drain Electrode The drain electrode is formed on the charge transporting material 4 by a method such as a sputtering method, a vapor deposition method, a plating method, an LPD method, or the like, preferably by a vapor deposition method with less damage to the charge transporting material. Form 2. At the same time, if necessary, the drain electrode 2 is patterned into a desired wiring pattern to complete the switching element.

Next, FIG. 7 is a sectional view showing the outline of the method of manufacturing the insulated gate SIT.

The steps (1) to (4) are the same as the method of manufacturing the Schottky gate type SIT. However, the material of the gate electrode is not limited to a metal having a small work function,
For example, P, Pt, Au, Pd, Ag, Cu, Ni, Co, I formed by sputtering an ITO film or the like
A metal film of n, W or the like is formed by a method such as a vapor deposition method, a sputtering method, or plating. Alternatively, a conductive polymer film of polyaniline, polypyrrole, polythiophene, or the like may be formed as a gate electrode film by a method such as coating or field polymerization.

Step (5) Formation of Gate Insulating Layer (Formation of Insulating Layer on Inner Surface of Gate Hole) Gate insulating layer such as polymer film of polyimide or metal oxide film or metal oxide film by a method such as electrodeposition or plating. 5 ',
It is selectively deposited on the inner surface of the gate hole and the upper surface of the gate electrode. Alternatively, the gate insulating layer 5 ′ may be formed by simply forming a surface oxide layer on the surface of the gate electrode by heating or the like.

Step (6) Formation of Charge Transporting Material The organic charge transporting material 4 is formed by a technique such as CVD, vapor deposition, coating, plating and LPD method. At this time, the inside of the gate hole is also filled.

Step (7) Formation of Drain Electrode The drain electrode is formed on the charge transporting substance 4 by a method such as a sputtering method, a vapor deposition method, a plating method and an LPD method, preferably a vapor deposition method which causes less damage to the charge transporting substance. Form 2. At the same time, if necessary, the drain electrode 2 is patterned into a desired wiring pattern to complete the switching element.

In any of the SIT manufacturing processes, when patterning the pattern forming film 7, the micro phase separation structure may be oriented by an external electric field before patterning. That is, for example, in the cylinder type phase separation structure formed by a PS-PMMA block copolymer or the like,
It is known that the cylinder phase is oriented along the lines of electric force. Therefore, a pattern forming film made of a block copolymer or a graft copolymer showing a cylinder type phase separation structure is formed on the gate electrode precursor film, and a voltage-impressed upper electrode layer is further formed on this pattern forming film. To do. When a microphase-separated structure is formed by applying heat to the gate electrode precursor film and the upper electrode while applying a voltage, the microphase-separated structure in which the cylinder phase is oriented vertically to the gate electrode is formed. After forming the Migros phase separation structure, remove the upper electrode layer,
Similar to the described gate electrode patterning method, the gate electrode can be etched.

According to this method, the cylinder phase is open to the gate electrode and the upper electrode (that is, the upper surface of the pattern forming film), which is particularly advantageous for processing the gate electrode by wet etching. Further, since a dot pattern having a very large aspect ratio is formed in the film thickness direction, it is also advantageous when RIE processing the gate electrode.

The switching elements as described above are arranged in a matrix and are used in a liquid crystal display or an E display.
A switching element array for driving a display device such as an L display can be configured. Known arrangements and wirings of the switching elements can be used. FIG. 8 is a wiring diagram of a switching element array for driving the EL display, and FIG. 9 shows an example of element arrangement of the switching element array for driving the EL display.

In FIG. 8, the scanning lines 15 and the signal lines 16 are wired in a grid pattern, and the switching element 11 and the switching element 12 are connected to each.
Furthermore, each switching element has a capacitor 14
And the EL element 13 is connected.

In FIG. 9, the scanning lines 15 and the signal lines 16 are wired in a grid pattern, the switching elements 11 and the capacitors 14 are arranged on the scanning lines 15, and the scanning lines 15 and the signal lines 16 are arranged between them. The switching element 12 is arranged, and an EL element (not shown) is arranged below the switching element 12.

In the case of a switching element array for driving a current drive type light emitting element such as an EL display,
By stacking the switching element behind the light emitting element as shown in the layout of FIG. 9, it becomes possible to secure a sufficient ON current. Such an arrangement is most preferable from the viewpoint of characteristics and process in the switching element of the present invention having a vertical laminated structure.

Such a switching element array can be manufactured by appropriately combining an ordinary photolithography process and the above-described gate hole forming process according to the present invention.

[0133]

EXAMPLES The present invention will be specifically described below based on examples.

However, the present invention is not limited to these examples.

Example 1 Manufacturing of Schottky Gate Switching Element A method of manufacturing the Schottky gate switching element of the present invention will be described below.

First, gold, which is a source electrode material, is deposited on the surface of a polyether sulfone film on a substrate provided with an undercoat film of silicon oxide by an ordinary vapor deposition method.
The film was formed with a film thickness of 0 nm. Then, a source electrode was formed by patterning into a desired shape by a photolithography process and a wet etching process.

Next, silicon oxide, which is a raw material for the gate insulating film, was formed into a film having a thickness of 20 nm by a sputtering method to form a gate electrode supporting insulating film.

Further, an aluminum film having a film thickness of 20 nm was formed on the gate electrode supporting insulating film by a usual vapor deposition method to form a gate electrode precursor film.

On this gate electrode precursor film, a polystyrene (PS) -polymethylmethacrylate (PMMA) diblock copolymer (1) (molecular weight Mw = 35) was used.
10,000, Mw / Mn = 1.02, polystyrene molecular weight: polymethylmethacrylate molecular weight = 2: 8) was applied by a spin coating method to form a pattern forming film having a thickness of 65 nm. This pattern forming film was heat-treated in an oven at 200 ° C. for 10 minutes in a nitrogen atmosphere and then at 135 ° C. for 10 hours. The PMMA phase was decomposed by irradiating the pattern forming film with β-rays and removed by washing with a developing solution (mixed solution of methyl isobutyl ketone and isopropyl alcohol in a weight ratio of 3: 7) to make the pattern forming film porous. Observation of the porous film with an atomic force microscope (AFM) showed about 7
At least 10 or more regions having a dot pattern in which 0 nm holes were arranged in a triangular lattice pattern were arranged. Furthermore, the orientation axis of the dot-shaped pattern forming the triangular lattice in each area was different from the orientation axis in the adjacent area.

Wet etching was performed using the porous pattern forming film as an etching mask to form a gate electrode. A solution of poly (3-hexylthiophene) was applied onto this gate electrode to form a charge transporting layer. Further, gold, which is a raw material for the drain electrode, is deposited by a conventional vapor deposition method.
The film was formed with a film thickness of 0 nm.

Then, a drain electrode was formed by patterning into a desired shape by a photolithography process and a wet etching process.

A PMMA solution was applied to the entire device using a bar coater to prepare a Schottky gate type switching device of the present invention as a protective film.

The characteristics of this switching element are that the current density when applying 10 V between the source electrode and the drain electrode = 0.7 A / cm ² , the ON / OFF ratio (I _ON / I _{OFF) of the} current between the source electrode and the drain electrode. ) = 10 ⁵ or more, which is a good characteristic for driving an EL element or the like. Example 2 Manufacturing Method of Insulated Gate Switching Element A manufacturing method of the insulated gate switching element of the present invention will be described below.

First, gold as a source electrode material was formed into a film having a thickness of 100 nm on a substrate having an undercoat film made of silicon oxide provided on the surface of a glass plate, by an ordinary vapor deposition method. Then, a source electrode was formed by patterning into a desired shape by a photolithography process and a wet etching process.

Next, silicon oxide, which is a raw material for the gate electrode supporting insulating film, was formed into a film having a thickness of 20 nm by a sputtering method to form a gate electrode supporting insulating film. Further, a film thickness of 20 nm is formed on the gate electrode supporting insulating film by a normal vapor deposition method.
The above gold film was formed into a gate electrode precursor film.

On the gate electrode precursor film, polystyrene (PS) -polymethylmethacrylate (PMMA) diblock copolymer (1) (molecular weight Mw = 35) was used.
10,000, Mw / Mn = 1.02, polystyrene molecular weight: polymethylmethacrylate molecular weight = 2: 8) was applied by a spin coating method to form a pattern forming film having a thickness of 65 nm. This pattern forming film was heat-treated in an oven at 200 ° C. for 10 minutes in a nitrogen atmosphere and then at 135 ° C. for 10 hours. The PMMA phase was decomposed by irradiating the pattern forming film with β-rays and removed by washing with a developing solution (mixed solution of methyl isobutyl ketone and isopropyl alcohol in a weight ratio of 3: 7) to make the pattern forming film porous. Observation of the porous film with an atomic force microscope (AFM) showed about 7
At least 10 or more regions having a dot pattern in which 0 nm holes were partially arranged in a triangular lattice were arranged.

Wet etching was performed using the porous pattern forming film as an etching mask to form a gate electrode. A polyimide thin film was electrodeposited on this gate electrode. The electrodeposition solution of the polyimide thin film was prepared as follows. Biphenyl tetracarboxylic dianhydride 6 g and p
2.2 g of phenylenediamine was reacted in 100 g of N-methylpyrrolidone under a nitrogen stream to obtain a polyamic acid solution. 4.2 g of this polyamic acid solution was added to N, N-
Diluted with 67 g of dimethylformamide, 0.0
68 g of triethylamine was added with good stirring.
Further, methanol was added with good stirring to obtain a polyamic acid salt 0.01% electrodeposition solution. Using this electrodeposition solution, electrodeposition was performed using the gate electrode as the anode and the stainless steel plate as the cathode to deposit a thin film of polyamic acid on the surface of the gate electrode. Then, it was heated at 250 ° C. for 60 minutes to convert the polyamic acid thin film into a polyimide film to form a gate insulating film.

A solution of poly (3-hexylthiophene) was applied on the gate electrode on which the gate insulating film was formed to form a charge transporting layer.

Further, gold as a drain electrode raw material was formed into a film having a thickness of 100 nm by a usual vapor deposition method. Then, a drain electrode was formed by patterning into a desired shape by a photolithography process and a wet etching process.

A PMMA solution was applied to the entire device using a bar coater to prepare a Schottky gate type switching device of the present invention as a protective film.

The characteristics of this switching element are that the current density when applying 10 V between the source electrode and the drain electrode = 0.5 A / cm ² , the ON / OFF ratio of the current between the source electrode and the drain electrode (I _ON / I _OFF ) = 10 ⁵ or more, which is a good characteristic for driving an EL element or the like.

Example 3 Manufacturing Method of Switching Element Array A switching element array shown in FIGS. 8 and 9 was manufactured by the following method.

10 to 20 are schematic views showing the manufacturing process of the switching element array of this embodiment.

I was formed on a substrate provided with an undercoat film of silicon oxide on the surface of a polyethersulfone film.
The TO electrode 20 was formed on the entire surface. An EL electrode 21 was formed as a pixel electrode by mask-depositing an aluminum electrode according to a pixel pattern. (FIG. 10 (1)).

Next, an insulating layer 22 of a photosensitive polyimide film having a thickness of 1 μm is formed, and the contact hole 2 is formed on each pixel electrode.
3 was provided (FIG. 11 (2)).

Next, after depositing gold on the entire surface, patterning was performed by a photolithography process to form a wiring pattern 25 of the scanning line and a drain electrode pattern 24 of the switching element 12 (FIG. 12C).

A polysilazane solution was applied thereon by a dip coating method to give a thickness of 10 n on the drain electrode.
Insulating layer 26 for supporting gate electrode of polysilazane
Was formed (FIG. 13 (4)).

Subsequently, aluminum was vapor-deposited on the entire surface to form a gate electrode precursor film. This precursor film was patterned by a photolithography process to form gate electrode patterns 27 and 28 of the switching elements 11 and 12 (FIG. 14 (5)).

Photosensitive polyimide 29 was applied to form an opening 30 and a contact hole 31 on the gate electrode.

Polystyrene (PS) -polymethylmethacrylate (PMMA) diblock copolymer (1) (molecular weight Mw = 350,000, Mw / Mn = 1.02,
Polystyrene molecular weight: Polymethylmethacrylate molecular weight =
2: 8) was applied by a dip coating method to form a pattern forming film having a film thickness of about 65 nm. After heat treatment in a nitrogen atmosphere to form a microphase-separated structure in the pattern forming film, β-ray irradiation was performed. After irradiation, the developing solution (weight ratio of methyl isobutyl ketone and isopropyl alcohol is 3: 7).
The PMMA phase was removed by washing with a mixed solution (1) to make the pattern forming film porous. The precursor film and the gate electrode supporting insulating layer were etched and made porous by using this pattern forming film as an etching mask. (FIG. 15 (6)).

After removing the pattern forming film, poly (3-
Hexylthiophene) solution was applied over the entire surface. Next, after depositing gold on the entire surface, patterning was performed by a photolithography process to form the charge transporting material layer of the switching elements 11 and 12, the source electrode 32, and the contact hole 33 (FIG. 16 (7)).

Further, after applying photosensitive polyimide on the entire surface, contact holes 34 are formed directly on the source electrodes of the switching elements 11 and 12 and on the lead-out portions of the gate electrodes (FIG. 17 (8)). After depositing aluminum on the entire surface. Then, patterning was performed by a photolithography process to form a signal line 35 and a capacitor electrode 36 (FIG. 18 (9)).

Photosensitive polyimide was applied to form a contact hole 37 on the source electrode of the switching element 12. (FIG. 19 (10)).

After Al was vapor-deposited on the entire surface, an aluminum laminate film 38 was covered as a back substrate and sealed, to fabricate an EL display device comprising the switching element array of the present invention (FIG. 20 (11)).

This EL display device has a switching element 12
Since the ON current value of was sufficient, the display brightness was excellent.

[0166]

As described above in detail, according to the manufacturing method of the switching element of the present invention, the gate hole is sufficiently large for manufacturing the SIT gate electrode using the organic semiconductor which can be manufactured at a low temperature as the active layer. It is possible to obtain a gate electrode which is small and has uniform gate holes and is excellent in durability, and an SIT type switching element having good switching characteristics can be easily manufactured at low cost.

According to the switching element of the present invention, it is possible to obtain an SIT type switching element having good switching characteristics in the SIT type switching element using an organic semiconductor which can be manufactured at a low temperature as an active layer.

Further, by applying such a switching element to a switching element array, a wide range of applications to various flat panel displays and the like are expected, and its industrial value is extremely large.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the structure of SIT.

FIG. 2 is a partial plan view of a gate electrode according to the present invention.

FIG. 3 is a cross-sectional view showing a device structure of a Schottky gate type SIT having a structure in which a gate electrode is supported by an insulating layer.

FIG. 4 is a sectional view showing an element structure of an insulated gate SIT.

FIG. 5 is a cross-sectional view showing an element structure of an insulated gate SIT having a structure in which a gate electrode is supported by an insulating layer.

FIG. 6 is a cross-sectional view schematically showing a method of manufacturing a Schottky gate type SIT.

FIG. 7 is a cross-sectional view showing an outline of a method of manufacturing an insulated gate SIT.

FIG. 8 is a wiring diagram of a switching element array for driving an EL display.

FIG. 9 is a plan view showing an example of element arrangement of a switching element array for driving an EL display.

FIG. 10 is a schematic view showing a manufacturing process of the switching element array of the third embodiment.

FIG. 11 is a schematic view showing a manufacturing process of the switching element array of the third embodiment.

FIG. 12 is a schematic view showing the manufacturing process of the switching element array of Example 3;

FIG. 13 is a schematic view showing the manufacturing process of the switching element array of Example 3;

FIG. 14 is a schematic view showing the manufacturing process of the switching element array of Example 3;

FIG. 15 is a schematic view showing the manufacturing process of the switching element array of Example 3;

FIG. 16 is a schematic view showing the manufacturing process of the switching element array of Example 3;

FIG. 17 is a schematic view showing the manufacturing process of the switching element array of Example 3;

FIG. 18 is a schematic view showing the manufacturing process of the switching element array of Example 3;

FIG. 19 is a schematic view showing the manufacturing process of the switching element array of Example 3;

FIG. 20 is a schematic view showing a manufacturing process of the switching element array of the third embodiment.

[Explanation of symbols]

1 ... Source electrode 2 ... Drain electrode 3 ... Gate electrode 4 ... Charge transport material (semiconductor layer) 5 ... Insulator layer 5 '... gate insulating layer 6 ... Substrate 7 ... Pattern forming film 8 ... Opening 9 ... Area 10 ... Alignment axis 11 ... Switching element 12 ... Switching element 13 ... EL light emitting element 14 ... Capacitor 15 ... Scan line 16 ... Signal line 17 ... Substrate 20 ... ITO electrode 21 ... EL light emitting pixel 22 ... Insulating layer 23 ... Contact hole 24 ... Drain electrode pattern 25 ... Scan line wiring pattern 26 ... Gate electrode supporting insulating layer 27 ... Gate electrode pattern of switching element 11 28 ... Gate electrode pattern of switching element 12 29 ... Polyimide film 30 ... Opening 31 ... Contact hole 32 ... Source electrode 33 ... Contact hole 34 ... Contact hole 35 ... Signal line pattern 36 ... Capacitor electrode 37 ... Contact hole 38 ... Aluminum laminated film

(72) Inventor Kazushige Yamamoto 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Toshiba Research & Development Center, Inc. (72) Inventor Masahiko Yamamoto 1 Komu-shi, Toshiba-cho, Kawasaki-shi, Kanagawa Toshiba Corporation Research & Development Center (56) Reference JP 2000-286479 (JP, A) JP 1-209767 (JP, A) JP 63-140576 (JP, A) International publication 90/08402 ( WO, A1) IEICE Technical Report, Japan, The Institute of Electronics, Information and Communication Engineers, July 3, 1998, CPM98-48-58, Vol. 98, No. 163, p. 25-30 Japan Journal of Applied Physics Part 1, Japan, Journal of Applied Physics, January 15, 1999, Vol. 38, No. 1A, p. 256-259 (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 29/80 H01L 29/812 H01L 29/786 H01L 51/00

Claims (10)

(57) [Claims] 1. An electrode pair composed of a source electrode and a drain electrode, a sheet-shaped gate electrode inserted between the source electrode and the drain electrode and having a plurality of through holes, and in the through hole of the gate electrode and In a method of manufacturing a switching element, which comprises an electron-transporting or hole-transporting organic charge-transporting substance that is at least partially filled in a space between electrode pairs, the gate electrode is made of a substance that constitutes the gate electrode. A first step of forming a gate electrode precursor film that is a thin film, a second step of forming a thin film of a compound that forms a micro phase separation structure on the gate electrode precursor film, and a formation of the micro phase separation structure Third step of forming the micro phase separation structure in a thin film of a compound, and selectively removing at least one phase of the formed micro phase separation structure Manufactured by performing a fourth step of forming a porous film and a fifth step of forming a gate electrode having a plurality of holes by etching the gate electrode precursor film using the porous film as an etching mask. A method of manufacturing a switching element, comprising: 2. The compound in the second step contains at least a block copolymer or a graft copolymer, and the block copolymer or the graft copolymer is composed of at least two kinds of polymer block chains. Two
The dry etching rate ratio of one kind of polymer block chain is 1.
3. The method of manufacturing a switching element according to claim 1, wherein the number of the elements is 3 or more, and the porous film is formed by dry etching in the fourth step. 3. The compound in the second step contains at least a block copolymer or a graft copolymer, and the block copolymer or the graft copolymer is composed of at least two kinds of polymer block chains. The main chain of at least one kind of polymer block chain is a decomposable block chain that is decomposed by energy ray irradiation, and in the fourth step, the porous film is formed by irradiating a phase composed of the decomposable block chain with an energy ray. The method for manufacturing a switching element according to claim 1, wherein the method is performed by disassembling and removing the element. 4. The compound in the second step contains at least a block copolymer or a graft copolymer, and the block copolymer or the graft copolymer contains at least a heat-resistant block chain and a pyrolytic block chain. A polymer block chain of a kind, and in the fourth step, the formation of the porous film is performed by selectively removing a phase composed of the thermally decomposable block chain by heat treatment. 1. The method for manufacturing a switching element according to 1. 5. A switching element comprising: an electrode pair formed of a source electrode and a drain electrode; and a gate electrode inserted between the source electrode and the drain electrode without contacting the electrode pair. The electrode has a plurality of through holes each having one surface facing the source electrode and the other surface facing the drain electrode, each surface having an opening, and the opening is the closest opening. A plurality of dot-shaped regions forming a triangular lattice at least partially between them, and at least partially electron-transporting or hole-transporting in the through hole of the gate electrode and the space between the electrode pair. A switching element characterized by being filled with an organic charge transporting material. 6. The dot-shaped pattern formed by the opening of the through hole of the gate electrode is formed by transferring a micro phase separation structure formed of a block copolymer or a graft copolymer. The switching element according to claim 5. 7. The switching element according to claim 5, wherein the gate electrode is held by a porous insulating film formed on at least one of the source electrode and the drain electrode. 8. The switching element according to claim 5, wherein the gate electrode and the charge transporting material form a Schottky junction. 9. The gate electrode is made of aluminum or its alloy, and the charge transport material is thiophene,
The switching element according to claim 5, wherein the switching element comprises at least one selected from the group consisting of pyrrole, phenylene, phenylene vinylene, thienylene vinylene, and oligomers of these derivatives. 10. A switching element array for a display device comprising the switching element according to claim 5.