JP2008171861A - Organic thin-film transistor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-durability organic thin-film transistor. <P>SOLUTION: The organic thin-film transistor comprises a gate electrode, a gate insulating film, an organic semiconductor layer made of an organic semiconductor material, and source and drain electrodes and has a protective layer, comprising an organic inorganic hybrid layer containing a water-soluble polymer and hydrolysis polycondensate of alkoxysilane expressed by general Formula 1 on the organic semiconductor layer. In this case, the general Formula 1 is R<SB>4-n</SB>Si(OR')<SB>n</SB>. In the Formula, R indicates a hydrogen atom or a substituent selected from among alkyl, halogenated alkyl, alkenyl, alkynyl, cycloalkyl, aryl, heteroaryl, and alkylsilyl groups, R' indicates a hydrogen atom or an alkyl group, and n indicates an integer of 2-4. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an organic thin film transistor using an organic semiconductor layer.

  With the widespread use of information terminals, there is an increasing need for flat panel displays as computer displays. In addition, with the progress of computerization, the information that has been provided in paper media has been increasingly digitized. As a mobile display medium that is thin, light, and easy to carry, it has become electronic paper or digital paper. Needs are growing.

  In general, in a flat panel display device, a display medium is formed using elements utilizing liquid crystal, organic EL (organic electroluminescence), electrophoresis, or the like. In such a display medium, an active driving method using a thin film transistor element (TFT element) has become mainstream as an image driving method in order to ensure uniformity of screen luminance, screen rewriting speed, and the like. For example, in a normal computer display, these TFT elements are formed on a glass substrate, and liquid crystal, organic EL elements, etc. are sealed.

  Here, semiconductors such as a-Si (amorphous silicon) and p-Si (polysilicon) are mainly used for the TFT element, and these Si semiconductors (and metal films as necessary) are formed into a multilayer structure. The TFT element is manufactured by sequentially forming the drain and gate electrodes on the substrate. The manufacture of such TFT elements usually requires sputtering or other vacuum manufacturing processes.

  However, in these Si-based TFT elements, it is necessary to form a large number of layers such that a plurality of semiconductor layers such as p-type and n-type are stacked only on a semiconductor layer that is necessary for a switching operation. Since the formation of the layer requires a vacuum manufacturing process including a vacuum chamber, the apparatus cost and running cost are extremely large. Furthermore, it is necessary to pattern the layer formed by these vacuum manufacturing processes by means such as photolithography, and in this patterning process, it is necessary to perform a number of steps such as exposure, development, and washing, and as a result In order to form the element on the substrate, dozens of processes are required. In such a conventional manufacturing method using a Si semiconductor, it is not easy to change the equipment, for example, a design change of a manufacturing apparatus such as a vacuum chamber is required in response to the need for a large display screen.

  Further, since the formation of such a conventional TFT element using a Si material includes a high temperature process, the base material is restricted to be a material that can withstand the process temperature. Therefore, in practice, glass must be used, and when the above-described thin display such as electronic paper or digital paper is configured using such a conventionally known TFT element, the display is heavy and flexible. Products that may break due to chipping or dropping impact. These characteristics resulting from the formation of Si-based TFT elements on a glass substrate are undesirable for a portable thin display for easy use accompanying the progress of computerization.

  Therefore, in recent years, attention has been focused on organic thin film transistor elements (organic TFT elements) using an organic material for a semiconductor layer. For example, as a semiconductor layer, acenes such as pentacene and tetracene, compounds having substituents introduced therein, phthalocyanines and porphyrins, and precursors thereof, low molecular compounds such as perylene and tetracarboxylic acid derivatives thereof, and α-thienyl Alternatively, aromatic oligomers, typically thiophene hexamers called sexual thiophenes, naphthalenes, anthracenes, 5-membered aromatic heterocycles condensed symmetrically, and hetero-condensed polymers such as diphenyl (benzothiophenobenzothiophene) Since ring compounds and the like are known and can be deposited and formed at a lower temperature than a-Si, formation on plastic films and the like has also been attempted. Manufacturing by such a low temperature process makes it possible to form TFT elements on a transparent resin substrate, making the display lighter and more flexible than conventional ones, and not broken (or very difficult to break) when dropped. It is thought that it can be.

  Furthermore, if it can be solubilized in a solvent by appropriately improving the molecular structure of these organic semiconductor materials, patterning is possible by a simple solution process such as an ink jet method or a printing method, and exposure and development associated with photolithography -It is expected that a number of processes such as washing can be reduced and a display can be manufactured by a simple process.

  By the way, these TFT elements are further connected to voltage drive elements or current drive elements such as liquid crystal display elements and organic EL elements, and are elements that have the role of adjusting the amount of current, so that the TFT elements are formed. After that, a display panel is formed through many processes. In these subsequent processes, a protective layer is applied to protect the TFT element from physical deterioration factors such as contact with mechanical parts, transportation, heating, exposure, and chemical deterioration factors due to oxygen, moisture, etc. in the environment. Need to form.

  However, an organic semiconductor layer made of an organic semiconductor is generally vulnerable to these stresses, and in the method of forming a protective layer by plasma CVD or sputtering such as an a-Si thin film transistor, the organic semiconductor layer deteriorates due to the thin film formation process itself. It had the problem of end.

  For such a problem, a method (for example, see Patent Document 1) in which a protective layer is formed by a solvent-free low temperature process such as a parylene thin film has been proposed. This method can be vapor-deposited at a low temperature and causes little damage to the organic semiconductor layer. However, since it is vapor deposition, direct patterning cannot be performed, and patterning must be performed by a technique such as photolithography. Moreover, since it is a vapor deposition method, it is difficult to form a large area uniformly.

Further, a method has been proposed in which a protective layer is formed by applying an aqueous solution containing a water-soluble polymer and a photosensitive agent (NH ₄ ) Cr ₂ O ₇ (see, for example, Patent Document 2). However, it is practically difficult to use dichromic acid, which is harmful to the environment, as a crosslinking agent for imparting sufficient solvent resistance to the protective layer. Further, the water-soluble polymer has a water absorption property, and may cause expansion / contraction due to humidity after film formation. In an actual use environment, the semiconductor layer is adversely affected over time due to humidity fluctuation. In general, organic substances alone are inferior in barrier properties such as oxygen and moisture, and protection of organic thin film transistors may be insufficient depending on applications.

Therefore, a method of suppressing the humidity change of the water-soluble polymer by forming the second protective layer made of an inorganic substance having a high gas barrier property on the water-soluble polymer thin film and preventing the permeation of moisture to the semiconductor layer. (For example, see Patent Document 3) has also been proposed. However, the adhesiveness between the first protective layer made of an organic material and the second protective layer made of an inorganic material is low, and has problems such as peeling off over time. It remained inadequate.
JP 2004-288774 A US Patent Application Publication No. 2002 / 022,299 JP 2005-277238 A

  An object of the present invention is to provide an organic thin film transistor having high durability.

  The above object of the present invention can be achieved by the following configuration.

  1. An organic thin film transistor having a gate electrode, a gate insulating film, an organic semiconductor layer made of an organic semiconductor material, a source electrode and a drain electrode, and hydrolyzing a water-soluble polymer and an alkoxysilane represented by the following general formula (1) An organic thin film transistor comprising a protective layer made of an organic-inorganic hybrid layer containing a polycondensate on the organic semiconductor layer.

General formula (1) R _4-n Si (OR ′) _n
Wherein R represents a hydrogen atom or a substituent selected from an alkyl group, a halogenated alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an aryl group, a heteroaryl group, an alkylsilyl group and a carbonyl group; Represents a hydrogen atom or an alkyl group, and n represents an integer of 2 to 4.)
2. 1-30 mass% of inorganic polymer compounds represented by the following general formula (2) obtained by hydrolytic polycondensation of the alkoxysilane represented by the general formula (1) to the organic-inorganic hybrid layer. 2. The organic thin film transistor according to 1 above, which is contained.

General formula (2) R _4-n SiO _{n / 2}
(In the formula, R represents a hydrogen atom or a substituent selected from an alkyl group, a halogenated alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an aryl group, a heteroaryl group, and an alkylsilyl group, and n represents 2 to 4) Represents an integer.)
3. 3. The organic thin film transistor according to 1 or 2 above, wherein n = 4 in the general formula (1) and the general formula (2).

  4). The water-soluble polymer is polyvinyl alcohol, halogenated polyvinyl alcohol, polyvinyl acetal, polyvinyl butyral, polyvinyl pyrrolidone, copolymers thereof, alkyl cellulose, hydroxyalkyl cellulose, cellulose ester, starch and derivatives thereof, gelatin, casein, albumin 4. The organic thin film transistor according to any one of 1 to 3, which is a water-soluble polymer selected from natural rubber and a mixture thereof.

  5. 5. The organic thin film transistor as described in 4 above, wherein the water-soluble polymer is polyvinyl alcohol.

  6). 6. The organic thin film transistor according to any one of 1 to 5, wherein the protective layer is formed by applying and drying an aqueous solution containing at least 50% by mass or more of water.

  7. After forming the protective layer containing the water-soluble polymer, the alkoxysilane represented by the general formula (1) and the photoacid generator, the pattern is exposed to actinic rays to generate an acid in the exposed area. 7. The organic thin film transistor according to any one of 1 to 6 above, wherein an organic-inorganic hybrid layer is formed only in an exposed portion with the acid.

  8). 8. The organic thin film transistor according to 7 above, wherein the photoacid generator is a sulfonium salt compound.

  9. 9. The method according to any one of 1 to 8, further comprising a second protective layer made of a metal oxide, a metal nitride, or a metal oxynitride on the protective layer made of the organic-inorganic hybrid layer. Organic thin film transistor.

  10. 10. The organic thin film transistor as described in 9 above, wherein the second protective layer is a protective layer made of silicon oxide.

  11. 11. The organic thin film transistor as described in 9 or 10 above, wherein the second protective layer is formed by a plasma CVD method under atmospheric pressure or a pressure near atmospheric pressure.

  12 12. The organic thin film transistor according to any one of 1 to 11, wherein the organic semiconductor layer is formed by coating using a non-aqueous solvent.

  According to the present invention, an organic thin film transistor having high durability can be provided.

  The organic thin film transistor of the present invention is an organic thin film transistor having a gate electrode, a gate insulating film, an organic semiconductor layer made of an organic semiconductor material, a source electrode and a drain electrode, and is represented by the water-soluble polymer and the general formula (1). The organic thin film transistor is characterized by having a protective layer composed of an organic-inorganic hybrid layer containing a hydrolyzed polycondensate of alkoxysilane formed on the organic semiconductor layer.

  Furthermore, it is preferable to laminate | stack the 2nd protective layer which consists of an inorganic layer on a protective layer (1st protective layer), By including an inorganic component in a 1st protective layer, it is with a 2nd protective layer. Adhesiveness becomes favorable and an organic thin film transistor with higher durability can be obtained.

  In the present invention, there is a feature that even if a protective layer is formed by coating on an organic semiconductor layer made of a soluble organic semiconductor, the organic semiconductor layer is not affected.

  Such an effect of the present invention is manifested by mixing the organic polymer and the inorganic substance in the protective layer, and by substantially forming a highly crosslinked structure by the interaction between the organic polymer and the inorganic substance. It is estimated to suppress the humidity fluctuation. Moreover, by forming an inorganic thin film having excellent water vapor barrier properties on the organic-inorganic hybrid layer (first protective layer) as the second protective layer, it is possible to further suppress performance deterioration due to humidity fluctuations. Since the inorganic substance is dispersed in a nano-size in the thin film, it is estimated that the adhesiveness is good.

  Hereinafter, the present invention will be described in more detail.

  Hereinafter, the constitution of the organic thin film transistor of the present invention, and then the materials and manufacturing methods of the respective layers constituting the organic thin film transistor of the present invention will be described.

<Structure of organic thin film transistor>
The configuration of the organic thin film transistor of the present invention will be described.

  The organic thin film transistor of the present invention is formed of a base material, a gate electrode, a gate insulating film, an organic semiconductor layer, a source electrode, and a drain electrode, and is a type of transistor generally called a MIS type (metal-insulator-semiconductor type) transistor. .

  In the MIS transistor, the electric field applied to the gate electrode is adjusted to control the conductivity of the semiconductor layer through the insulating layer, and as a result, the amount of current flows from the source electrode installed at both ends of the semiconductor layer to the drain electrode. Can be controlled.

  Among such MIS transistors, they can be classified into several types depending on the structure of each layer.

  First, a top gate type having a source electrode and a drain electrode connected by an organic semiconductor film (hereinafter also referred to as an organic semiconductor layer) on a substrate, and having a gate electrode on the gate electrode via a gate insulating layer, First, it is roughly classified into a bottom gate type having a gate electrode and having a source electrode and a drain electrode connected by an organic semiconductor film through a gate insulating layer.

  Furthermore, when viewed from the gate electrode, the source electrode and the drain electrode can be distinguished into a bottom contact type in front of the organic semiconductor layer and a top contact type on the other side of the organic semiconductor layer, and by combining both, Four types of organic thin film transistors can be configured. An example of a specific layer structure of the element is shown in FIGS. 1 (a) to 1 (e) below.

  FIGS. 1A and 1C show top gate / bottom contact layer configuration examples. A source electrode 102 and a drain electrode 103 are provided on a base 106, and an organic semiconductor film 101 is formed thereon. Further, the gate insulating layer 105 is formed in contact with the organic semiconductor film 101, and the source electrode 104 is provided thereover.

  FIG. 1B shows an example of a layer structure of a top gate / top contact type. A base electrode 106 is provided on a base 106, and a gate insulating layer 105 is formed thereon. The organic semiconductor film 101 is formed thereon, and the source electrode 102 and the drain electrode 103 are formed in contact with the organic semiconductor film 101.

  FIGS. 1D and 1F show an example of a bottom gate / bottom contact type layer structure. A base electrode 106 is provided on a base 106, and a gate insulating layer 105 is formed thereon. The source electrode 102 and the drain electrode 103 are formed thereon, and the organic semiconductor film 101 is formed thereon.

  FIG. 1E shows an example of a layer structure of a bottom gate / top contact type. A base electrode 106 is provided on a base 106, and a gate insulating layer 105 is formed thereon. The organic semiconductor film 101 is formed thereon, and the source electrode 102 and the drain electrode 103 are formed thereon.

  Among these configurations, in the case of the top gate structure as in (a) to (c), the organic semiconductor layer is substantially enclosed in the element, and thus the protective layer is not necessarily required. It is very difficult and practical to form and pattern a gate insulating film and a gate electrode on the organic semiconductor layer without causing deterioration of the film.

  The protective film of the present invention having the characteristic that it can be formed and patterned with low damage on the organic semiconductor layer is formed on the organic semiconductor layer 1 of the organic thin film transistor having the bottom gate structure as shown in (d) to (f). Thus, a practical organic thin film transistor can be formed.

  From such a viewpoint, it is preferable to have a bottom gate / bottom contact type configuration represented by the above (c) and (f). In these element configurations, only the protective layer may be formed on the organic semiconductor layer, the damage when forming other layers can be reduced most, and an organic thin film transistor having good characteristics with little deterioration is obtained. be able to.

  Hereinafter, the material and forming method of each layer forming the organic semiconductor will be described.

<Substrate>
Various materials can be used as a base (also referred to as a substrate) for forming an organic thin film transistor. For example, glass, quartz, aluminum oxide, sapphire, silicon nitride, silicon carbide and other ceramic bases, silicon, germanium, gallium A semiconductor substrate such as arsenic, gallium phosphide, and gallium nitrogen, paper, non-woven fabric, and the like, and a substrate made of a metal such as stainless steel or aluminum having a thickness that can be bent can be used. Preferably, for example, a plastic film sheet can be used.

  Examples of plastic films include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate (PC), and cellulose. Examples include films made of triacetate (TAC), cellulose acetate propionate (CAP), and the like. By using a plastic film, it is possible to reduce the weight as compared to the case of using a glass substrate, to improve portability, and to improve resistance to impact. Further, it becomes possible to incorporate or integrate a field effect transistor into a display device or electronic device having a curved shape.

  Further, in the organic thin film transistor of the present invention, when the substrate is a plastic film, an undercoat layer containing a compound selected from inorganic oxides and inorganic nitrides, and a polymer in order to improve the adhesion between the substrate and the organic thin film transistor It is preferable to have at least one of the undercoat layers containing.

  Examples of the inorganic oxide contained in the undercoat layer include silicon oxide, aluminum oxide, tantalum oxide, titanium oxide, tin oxide, vanadium oxide, barium strontium titanate, barium zirconate titanate, lead zirconate titanate, titanate Examples thereof include lead lanthanum, strontium titanate, barium titanate, barium fluoride magnesium, bismuth titanate, strontium bismuth titanate, strontium bismuth tantalate, bismuth tantalate niobate, and yttrium trioxide. Examples of the inorganic nitride include silicon nitride and aluminum nitride.

  Of these, silicon oxide, aluminum oxide, tantalum oxide, titanium oxide, and silicon nitride are preferable.

  In the present invention, as a method for forming an undercoat layer containing a compound selected from inorganic oxides and inorganic nitrides, the same method for forming an inorganic oxide or inorganic nitride as the above-described gate insulating film forming method is used. However, it is preferably formed by an atmospheric pressure plasma method.

  Polymers used for the undercoat layer containing polymer include polyester resin, polycarbonate resin, cellulose resin, gelatin, acrylic resin, polyurethane resin, polyethylene resin, polypropylene resin, polystyrene resin, phenoxy resin, norbornene resin, epoxy resin, vinyl chloride Vinyl acetate copolymer, vinyl chloride resin, vinyl acetate resin, copolymer of vinyl acetate and vinyl alcohol, partially hydrolyzed vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile Copolymers, ethylene-vinyl alcohol copolymers, polyvinyl alcohol, chlorinated polyvinyl chloride, ethylene-vinyl chloride copolymers, vinyl polymers such as ethylene-vinyl acetate copolymers, polyamide resins, ethylene-butadiene Down resin, a butadiene - rubber resin such as acrylonitrile resin, silicone resin, and fluorine resins.

<< Gate electrode, source electrode, drain electrode >>
Next, an electrode material for forming a gate electrode pattern and a source / drain electrode pattern and a method for forming the electrode material will be described.

  In the organic thin film transistor of the present invention, the material constituting the gate electrode pattern, the source / drain electrode pattern, and the wiring portion connecting the electrode and the power source can be formed of a known electrode material. The electrode material is not particularly limited as long as it is a conductive material. Platinum, gold, silver, nickel, chromium, copper, iron, tin, antimony lead, tantalum, indium, palladium, tellurium, rhenium, iridium, aluminum, ruthenium, germanium , Molybdenum, tungsten, tin oxide / antimony, indium tin oxide (ITO), fluorine doped zinc oxide, zinc, carbon, graphite, glassy carbon, silver paste and carbon paste, lithium, beryllium, sodium, magnesium, potassium, calcium, Scandium, titanium, manganese, zirconium, gallium, niobium, sodium, sodium-potassium alloy, magnesium, lithium, aluminum, magnesium / copper mixture, magnesium / silver mixture, magnesium / al Bromide mixture, a magnesium / indium mixture, aluminum / aluminum oxide mixture, a lithium / aluminum mixture, or the like is used. Alternatively, known conductive polymers whose conductivity is improved by doping or the like, for example, conductive polyaniline, conductive polypyrrole, conductive polythiophene (polyethylenedioxythiophene and polystyrenesulfonic acid complex, etc.) are also preferably used.

  In the case of the source / drain electrode pattern, those having a small electric resistance at the contact surface with the organic semiconductor layer are preferable, and when the semiconductor layer is a p-type semiconductor, platinum, gold, silver, and copper are preferable. Among them, gold is preferable because it has a small potential difference with respect to the organic semiconductor material and has a small carrier injection barrier from the electrode to the organic semiconductor. Further, since gold does not form an oxide film on the electrode surface due to oxidation or the like, there is no fear that the work function of the electrode surface changes.

  As a method for forming an electrode, a conductive thin film formed using a dry process such as vapor deposition or sputtering using the above as a raw material, and a method for forming an electrode shape using a known photolithography method or a lift-off method, aluminum, copper, or the like A method in which a resist is formed on a metal foil by thermal transfer, ink jet, etc., patterned by etching, transferred by laser ablation, etc., or a conductive polymer solution or dispersion containing metal fine particles, conductive ink, conductive A method of forming a functional paste or the like by a printing process such as relief printing, intaglio printing, planographic printing, screen printing, and ink jet printing, US Pat. No. 2,600,343, Japanese Patent Publication No. 42-23746, JP 2004 Photoreduction of silver halide grains described in JP-A-221565 That way, and the like.

  As a means for forming the shape of the gate electrode and the source / drain electrode, it is preferable to use a photolithographic method or an inkjet method.

  In addition, if the surface of the electrode is oxidized to form an oxide film, or if dirt due to organic matter or the like is attached, the reactivity with the electrode is reduced, and an organic semiconductor layer having a controlled thickness can be formed. Since it may be difficult, it is preferable to clean the electrode surface cleanly using a known cleaning method immediately before forming the organic semiconductor layer.

  Examples of such an electrode surface cleaning method include treatment with a strong acid / strong alkali, ultraviolet irradiation, ozone treatment, corona discharge treatment, plasma treatment and the like. Of these, plasma treatment is preferred, and atmospheric pressure plasma treatment is more preferred.

  The atmospheric pressure plasma treatment is a treatment in which a gas containing plasma generated by applying an electric field between opposing electrodes under atmospheric pressure is sprayed onto a substrate. In atmospheric pressure plasma processing, the density of active species is higher than in vacuum plasma processing, so the electrode surface can be processed at high speed and high efficiency. There is an advantage that you can. The atmospheric pressure plasma treatment can be performed with reference to JP-A No. 2003-309266.

<Gate insulation film>
Although various insulating films can be used as the gate insulating layer of the organic thin film transistor of the present invention, there are roughly two types, inorganic and organic, and there are formation methods suitable for each.

  For example, as inorganic substances, silicon oxide, aluminum oxide, tantalum oxide, titanium oxide, tin oxide, vanadium oxide, barium strontium titanate, barium zirconate titanate, lead zirconate titanate, lead lanthanum titanate, strontium titanate, titanium Metal oxides such as barium oxide, barium magnesium fluoride, bismuth titanate, strontium bismuth titanate, strontium bismuth tantalate, bismuth tantalate niobate, trioxide yttrium, etc., silicon nitride, aluminum nitride, boron nitride, titanium nitride, etc. Metal nitride, and the like.

  Insulating films formed from inorganic materials include vacuum deposition, molecular beam epitaxy, ion cluster beam, low energy ion beam, ion plating, chemical vapor deposition (CVD), and sputtering. If it can be formed from a dry process such as atmospheric pressure plasma CVD, which will be described later, a method of forming by oxidizing or nitriding the surface of the gate electrode, or a wet process such as a sol-gel method, the spray coating method , Spin coating method, blade coating method, dip coating method, casting method, roll coating method, bar coating method, die coating method, and other wet processes such as coating and inkjet printing methods that can be patterned simultaneously. Can be used depending on the material. Among these, it is preferable to use an anodic oxidation method, an atmospheric pressure plasma CVD method, and a combination thereof.

  Examples of organic substances include polymethyl methacrylate (PMMA), polyvinyl phenol (PVP), polyvinyl alcohol (PVA), polyimide, polyamide, polyester, polyacrylate, photo-radical polymerization, and photocationic polymerization such as epoxy resin and oxetane resin. Curable resin or copolymer containing acrylonitrile component, polyvinylphenol, polyvinyl alcohol, novolac resin, resin made from natural polysaccharides such as cyanoethyl pullulan and triacetyl cellulose, gelatin, low temperature chemical vapor deposition method An organic insulating material such as parylene formed in (1) can be used, and combinations thereof can also be used. These organic substances can be easily applied to the wet process described above, and the number of steps is small and the area can be easily increased. Therefore, the spray coating method, the spin coating method, the blade coating method, the dip coating method, the casting method, the roll coating method. It is preferably formed by a wet process such as a coating method such as a coating method, a bar coating method, or a die coating method, and a patterning method such as printing or inkjet. Among these, it is preferable to use a spin coating method, a printing method, or an ink jet method.

  Among these materials, it is preferable to use a material having a high dielectric breakdown voltage and a high relative dielectric constant. With a material having a high dielectric breakdown voltage, the film thickness of the insulating film can be reduced, the production speed can be increased, and the occurrence of cracks and peeling when the element is bent can be reduced. If a material having a high relative dielectric constant is used, a channel can be formed with a low gate voltage, and an organic thin film transistor that can be driven with a low voltage can be obtained. As an insulating film material satisfying such characteristics, silicon oxide, silicon nitride, polyvinylphenol, and polyimide can be preferably used.

  An inorganic oxide film and an organic oxide film can be laminated and used together. The thickness of these insulating films is generally 50 nm to 3 μm, preferably 100 nm to 1 μm.

  On the surface of the gate insulating layer, silane coupling agents such as octadecyltrichlorosilane and trichloromethylsilazane, alkanephosphoric acid, alkanesulfonic acid, and alkanecarboxylic acid are used for the purpose of modifying various properties such as flatness and surface energy. And a self-assembled alignment film made of the compounds described in Japanese Patent Application No. 2006-82419 may be formed on the surface of the insulating film.

  Among these, it is preferable to use a self-assembled alignment film formed from a silane coupling agent. When such a coating material having a functional group having reactivity with the surface of the insulating film is used, it can be formed with a monomolecular film thickness. Therefore, an organic thin film transistor element with high uniformity of film thickness and less variation is obtained. Obtainable.

<Organic semiconductor layer>
As an organic semiconductor material constituting the organic semiconductor layer, any material can be used without limitation as long as it can control the mobility of carriers by the electric field effect. However, the p-type semiconductor in which carriers are holes and the carriers are electrons. It can be roughly divided into n-type semiconductors. However, up to now, almost no n-type organic semiconductor material with high mobility and stability has been found, and the majority are p-type organic semiconductor materials. Note that even these relatively stable p-type organic semiconductor materials do not have sufficient durability against moisture, oxygen, heat, and stress, and it is necessary to form a protective layer on the organic semiconductor layer.

  Examples of the organic semiconductor material include various condensed polycyclic aromatic compounds and conjugated compounds.

  Examples of the condensed polycyclic aromatic compound include anthracene, tetracene, pentacene, hexacene, heptacene, chrysene, picene, fluorene, pyrene, peropyrene, perylene, terylene, quaterylene, coronene, ovalene, thacumanthracene, bisanthene, zeslen, heptazelene. , Pyranthrene, violanthene, isoviolanthene, cacobiphenyl, anthradithiophene, and the like, and derivatives and precursors thereof.

  Examples of the conjugated compound include polythiophene and its oligomer, polypyrrole and its oligomer, polyaniline, polyphenylene and its oligomer, polyphenylene vinylene and its oligomer, polythienylene vinylene and its oligomer, polyacetylene, polydiacetylene, tetrathiafulvalene compound, quinone Compounds, cyano compounds such as tetracyanoquinodimethane, fullerenes and derivatives or mixtures thereof.

  In particular, among polythiophene and oligomers thereof, thiophene hexamer, α-seccithiophene α, ω-dihexyl-α-sexualthiophene, α, ω-dihexyl-α-kinkethiophene, α, ω-bis (3- An oligomer such as butoxypropyl) -α-sexithiophene can be preferably used.

  Furthermore, porphyrin, copper phthalocyanine, metal phthalocyanines such as fluorine-substituted copper phthalocyanine described in JP-A No. 11-251601, naphthalene 1,4,5,8-tetracarboxylic acid diimide, N, N′-bis (4-tri Fluoromethylbenzyl) naphthalene 1,4,5,8-tetracarboxylic acid diimide, N, N'-bis (1H, 1H-perfluorooctyl), N, N'-bis (1H, 1H-perfluorobutyl) and N , N'-dioctylnaphthalene 1,4,5,8-tetracarboxylic acid diimide derivative, naphthalene tetracarboxylic acid diimides such as naphthalene 2,3,6,7 tetracarboxylic acid diimide, and anthracene 2,3,6,7 -Condensed rings such as anthracene tetracarboxylic acid diimides such as tetracarboxylic acid diimide Organics such as tracarboxylic acid diimides, tetrathiafulvalene (TTF) -tetracyanoquinodimethane (TCNQ) complex, bisethylenetetrathiafulvalene (BEDTTTTF) -perchloric acid complex, BEDTTTTF-iodine complex, TCNQ-iodine complex, etc. Molecular complexes, fullerenes such as C60, C70, C76, C78 and C84, carbon nanotubes such as SWNT, dyes such as merocyanine dyes and hemicyanine dyes, σ-conjugated polymers such as polysilane and polygerman, and JP 2000 Organic-inorganic hybrid materials described in -260999 can also be used.

  Among these π-conjugated materials, at least one selected from the group consisting of condensed polycyclic aromatic compounds such as pentacene, fullerenes, condensed ring tetracarboxylic acid diimides, metal phthalocyanines, and metal porphyrins is preferable.

  As a method for forming the organic semiconductor layer, physical vapor deposition methods such as a vacuum deposition method, an MBE (Molecular Beam Epitaxy) method, an ion cluster beam method, a low energy ion beam method, an ion plating method, and a sputtering method ( PVD method), chemical vapor deposition (CVD method), dry process, spin coating method, screen printing method, ink jet printing method, air doctor coater method, blade coater method, rod coater method, knife coater method, squeeze Coater method, reverse roll coater method, transfer roll coater method, gravure coater method, kiss coater method, cast coater method, spray coater method, slit orifice coater method, calender coater method, dipping method, spray method, dripping method, Langmier A solution process such as a Rojet method can be given, and an appropriate method may be used among these depending on the organic semiconductor material to be used.

  In the organic thin film transistor of the present invention, it is preferable to form the organic semiconductor layer by a solution process among the above processes. If it can be formed by a solution process, the number of steps can be greatly reduced, and not only can an organic thin film transistor be formed by a simple process, but also a crystal larger than that formed by a dry process can be formed. As a result, an organic thin film transistor having good mobility can be formed.

  However, in general, the above condensed polycyclic aromatic compounds and conjugated compounds have poor solubility, and in order to obtain a soluble organic semiconductor material, an organic group such as the above, an alkyl group, an alkylsilyl group, or a cycloalkyl group. It is preferable to use an organic semiconductor material solubilized in a solvent by adding a substituent such as a group or an aryl group.

  Examples of such a soluble organic semiconductor material include poly (3-hexylthiophene), polythiophene compounds having an alkyl group, and trialkyl as described in JP-A Nos. 2003-292588 and 2005-76030. Examples include acene compounds and heteroacene compounds having a silylethynyl group, and porphyrin compounds having a steric ring structure such as a bicyclo ring described in JP-A-2003-304104.

  The film thickness of these organic semiconductor layers is not particularly limited, but the characteristics of the obtained transistor are often greatly influenced by the film thickness of the organic semiconductor layer, and the film thickness varies depending on the organic semiconductor. In general, the thickness is 10 nm to 1 μm, preferably 20 to 200 nm, more preferably 30 to 100 nm.

《Protective layer》
The organic thin film transistor has a protective layer. By having the protective layer, the durability of the organic thin film transistor is improved. In the present invention, an organic-inorganic hybrid material is used as a protective layer.

  An organic-inorganic hybrid is a material that brings out a synergistic effect by combining an organic material and an inorganic material. The method is based on the so-called sol-gel method, in which metal alkoxides are hydrolyzed in solution to obtain inorganic polymers (inorganic oxides), so the formation of organic-inorganic hybrid materials is mainly based on solution processes. It is also easy to perform coating and patterning by a printing method, an inkjet method, or the like.

《Water-soluble polymer》
The organic thin film transistor of the present invention is characterized by having a protective layer composed of an organic-inorganic hybrid layer containing a water-soluble polymer and a hydrolyzed polycondensate of alkoxysilane represented by the general formula (1). Since a water-soluble polymer is used, a film can be formed using an aqueous solvent, so that the film can be formed without dissolving or damaging the organic semiconductor layer. Further, it is preferable because it is industrially inexpensive and harmless.

  The water-soluble polymer used in the present invention can be used without limitation as long as it is a water-soluble polymer. For example, polyvinyl alcohol, halogenated polyvinyl alcohol, polyvinyl acetal, polyvinyl butyral, polyvinyl pyrrolidone, and a copolymer of these. Examples include polymers, alkyl celluloses, hydroxyalkyl celluloses, cellulose esters, starches and derivatives thereof, gelatin, casein, albumin, natural rubber, and mixtures thereof. Among these, polyvinyl alcohol having low oxygen permeability is preferable.

<< Hydrolysis polycondensate of alkoxysilane represented by general formula (1), inorganic polymer compound represented by general formula (2) >>
The organic thin film transistor of the present invention has a protective layer comprising an organic-inorganic hybrid layer containing a water-soluble polymer and a hydrolyzed polycondensate of alkoxysilane represented by the general formula (1). .

  Moreover, the inorganic polymer compound represented by the said General formula (2) obtained by carrying out the hydrolysis polycondensation of the alkoxysilane represented by the said General formula (1) to the said organic-inorganic hybrid layer is 1-30. It is preferable to contain by mass. If the addition amount is 1% by mass or less, the modification effect of the organic polymer due to the addition of the inorganic polymer is difficult to obtain. Further, when the content is 30% by mass or more, the aggregation of the inorganic polymer is likely to occur, and the transparency and strength of the organic-inorganic hybrid molded product are likely to be lowered. More preferably, it is 3-15 mass%, More preferably, it is 5-10 mass%.

  In the general formula (1), OR ′ is preferably removed as much as possible until it is eliminated by the sol-gel reaction and mixed with the water-soluble polymer, so that it is preferably an alkoxy substituent having a molecular weight as small as possible. Accordingly, R ′ is preferably a C1-C4 alkyl group, more preferably a methyl group or an ethyl group. In addition, since substituents having an ether bond such as a methoxyethyl group and an ethoxyethyl group are easily mixed with an aqueous solvent, an alkoxy column having these substituents may be used as necessary.

  In the general formulas (1) and (2), R is a hydrogen atom or a substituent selected from an alkyl group, a halogenated alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an aryl group, a heteroaryl group, and an alkylsilyl group. Represents a group, and R may be optionally substituted with a hydrophilic group, a hydrophobic group, or a reactive group in order to enhance compatibility.

  Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a tert-butyl group, a pentyl group, a hexyl group, an octyl group, a dodecyl group, a tridecyl group, a tetradecyl group, and a pentadecyl group; As, for example, a trifluoromethyl group, 1,1,1-trifluoropropyl group, etc .; As an alkenyl group, for example, vinyl group, allyl group, etc .; As an alkynyl group, for example, ethynyl group, propargyl group, etc .; Examples of the cycloalkyl group include a cyclopentyl group and a cyclohexyl group; examples of the aryl group include a phenyl group, a p-chlorophenyl group, a mesityl group, a tolyl group, a xylyl group, a naphthyl group, an anthryl group, an azulenyl group, an acenaphthenyl group, and a fluorenyl group. Group, phenanthryl group, indeni Group, pyrenyl group, biphenylyl group and the like; examples of the heteroaryl group include furyl group, thienyl group, pyridyl group, pyridazinyl group, pyrimidinyl group, pyrazinyl group, triazinyl group, imidazolyl group, pyrazolyl group, thiazolyl group, quinazolinyl group, Examples of the alkylsilyl group such as a phthalazinyl group include a trimethylsilyl group, a triethylsilyl group, a tripropyl (i or n) silyl group, and a tributyl (i, t or n) silyl group.

  n represents an integer of 2 to 4. It may be a copolymer of n = 3 inorganic polymer and n = 4 inorganic polymer. In addition, since n = 3 alkoxysilane has one less condensable substituent than n = 4 alkoxysilane, the aggregation of the inorganic polymer is less likely to occur, and in order to reduce the aggregation property of the inorganic polymer, n = 3 or n = 2 compounds may be added. However, the modification effect of the organic polymer by the organic-inorganic hybrid tends to be higher as the number of alkoxy groups substituting silicon is larger. Therefore, it is preferable that the addition of n = 2 alkoxysilane is as small as possible.

  In general, an inorganic polymer obtained by polymerizing alkoxysilane with n = 4 is silica or silicon oxide, an inorganic polymer obtained by polymerizing alkoxysilane with n = 3 is silsesquioxane, and n = 2. An inorganic polymer obtained by polymerizing this alkoxysilane is referred to as polysiloxane. However, an inorganic polymer obtained from any alkoxysilane having n = 2 to 4 may be referred to as polysiloxane in a broad sense because the main chain is composed of Si—O bonds. In addition, only a dimer can be obtained only from the alkoxysilane of n = 1, and a high molecular weight body cannot be obtained.

  Specific examples of the alkoxysilane represented by the general formula (1) and n = 4 include, for example, tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), tetra n-propoxysilane, tetraisopropoxysilane, tetra Examples thereof include n-butoxysilane, tetra-t-butoxysilane, tetrakis (methoxyethoxy) silane, tetrakis (methoxypropoxy) silane, and tetraacetoxysilane. Alternatively, quantified silicon compounds such as silicate 40, silicate 45, silicate 48, and M silicate 51 manufactured by Tama Chemical may be used.

  In the present invention, alkoxysilane in which n = 4 is preferable.

  Specific examples of the alkoxysilane in which n = 3 include, for example, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-butyltrimethoxysilane, i-butyltrimethoxysilane, n-hexyltrimethoxysilane, cyclohexyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-amino Propyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, acetoxytriethoxysilane, ( Ptadecafluoro-1,1,2,2-tetrahydrodecyl) trimethoxysilane, (3,3,3-trifluoropropyl) trimethoxysilane, (3,3,3-trifluoropropyl) trimethoxysilane, penta Examples include fluorophenylpropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane.

  Examples of the alkoxysilane where n = 2 include dimethyldiethoxysilane and diphenyldimethoxysilane. As described above, these n = 2 alkoxysilanes can be used for controlling the cohesiveness of the polymerized inorganic polymer by adding a small amount during the polymerization of the alkoxysilanes with n = 3 and 4.

  These alkoxysilanes undergo hydrolysis polycondensation reaction by reacting with moisture in a solvent or in the absence of a solvent to produce an inorganic polymer.

  Moisture used for hydrolysis of alkoxysilane is stoichiometrically required to be n / 2 equivalent to alkoxysilane. However, in order to adjust the reactivity and degree of polymerization of alkoxysilane, the addition of moisture The amount may be n / 4 to n equivalent.

  In addition, when using a hydrophobic alkoxysilane, it is difficult to mix with water, so by dissolving in a hydrophilic organic solvent such as methanol, ethanol, acetone, acetonitrile so that the alkoxysilane is easily mixed with water, Alkoxysilane and water can be mixed uniformly, and the hydrolysis reaction can proceed rapidly and uniformly.

  In order to prevent deterioration of the organic semiconductor layer, the protective layer composed of the organic-inorganic hybrid layer containing the water-soluble polymer and the hydrolyzed polycondensate of alkoxysilane represented by the general formula (2) is at least 50. It is preferable to form by applying and drying an aqueous solution containing at least mass% of water.

  In the present invention, the degree of polymerization and cohesion of the inorganic polymer may change depending on the amount of the solvent used during the sol-gel reaction, so use a solvent having a mass 0.5 to 100 times the mass of the alkoxysilane. It is preferable to perform a sol-gel reaction. More preferably, a solvent having a mass of 0.7 to 20 times, more preferably 1 to 5 times, is used.

  In addition, the hydrolysis polycondensation reaction (sol-gel reaction) can proceed more rapidly by adding various catalysts.

  The sol-gel reaction can be accelerated by adding a catalyst. As a result, the modification effect of the obtained organic-inorganic hybrid molded product can be further enhanced.

  Such catalysts include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, 12 tungsto (VI) phosphoric acid, 12 molybdo (VI) phosphoric acid, silicotungstic acid and other inorganic acids, acetic acid, trifluoroacetic acid, levulinic acid, citric acid Organic acids such as p-toluenesulfonic acid and methanesulfonic acid are used. In addition, aliphatic amines such as ammonia, monoethanolamine, diethanolamine, triethanolamine, diethylamine and triethylamine, aromatic amines such as aniline, pyrrole, pyrazole and imidazole, DBU (diazabicycloundecene-1), DBN ( Bases such as bicyclo ring amines such as diazabicyclononene), ammonia, phosphine, alkali metal alkoxides, ammonium hydroxide, tetramethylammonium hydroxide, benzyltrimethylammonium hydroxide can be used. Further, Lewis acids such as acetates of metals such as germanium, titanium, aluminum, antimony and tin, other organic acid salts, halides and phosphates may be used in combination.

  Among these catalysts, when an acidic catalyst is used, it is preferable to use an acidic catalyst because an organic-inorganic hybrid molded product can be easily obtained with high transparency and strength. Furthermore, when a photoacid generator as described later is used, an acid can be generated only at a site irradiated with actinic rays, and further, an alkoxysilane hydrolysis polycondensation reaction occurs only at that site, and an organic-inorganic hybrid Since a layer is formed and insolubilized in a solvent, photopatterning can be performed, which simplifies the process.

  In addition, although there is no restriction | limiting in particular as the addition amount of these acid or alkali catalysts, Preferably 0.01-20 mass% is preferable with respect to the quantity of the alkoxysilane which can be polycondensed.

《Photoacid generator》
The organic thin-film transistor of this invention is exposed by carrying out pattern exposure of actinic rays by making it contain in the protective layer containing the said water-soluble polymer, the alkoxysilane represented by the said General formula (1), and a photo-acid generator. An acid is generated in the part, the exposed part is cured by the generated acid, the unexposed part is removed, and only the exposed part can be formed as an organic-inorganic hybrid layer. It is preferable to use such a method because patterning can be easily performed so as not to be formed at an electrical connection portion with a data line or the like of an organic thin film transistor.

As the photoacid generator used in the present invention, for example, a chemical amplification type photoresist or a compound used for photocationic polymerization is used (edited by Organic Electronics Materials Research Group, “Organic Materials for Imaging”, Bunshin Publishing ( 1993), pages 187-192). Suitable compounds for the present invention include, for example, B (C ₆ F ₅ ) ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , p of aromatic onium compounds such as diazonium, ammonium, iodonium, sulfonium and phosphonium. _{-CH 3 C 6 H 4 SO 3} - salt, CF ₃ SO ₃ ^- sulfonate, such as salts, sulfonated materials that generate a sulfonic acid, halide which generates hydrogen halide, but iron arene complex and the like, Preferred photoacid generators used in the present invention are onium salts such as sulfonium salts, iodonium salts, ammonium salts, phosphonium salts, etc. Among them, the acid generation ability is high, the polymerization reaction is fast, and the solvent resistance of the cured layer is high. A sulfonium salt compound capable of increasing durability is preferred.

  As a preferable sulfonium salt compound, a sulfonium salt compound represented by the following general formula (3) is preferable.

(In the formula, R _{31 to} R ₃₃ represent a monovalent substituent, and X ⁻ represents a counter anion.)
In the general formula (3), examples of the substituent represented by R _{31 to} R ₃₃ include a halogen atom (for example, a chlorine atom, a bromine atom, a fluorine atom, etc.), an alkyl group having 1 to 6 carbon atoms (for example, Methyl group, ethyl group, propyl group, isopropyl group, butyl group, etc.), cycloalkyl group having 3 to 6 carbon atoms (for example, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, etc.), 1 to 6 carbon atoms Alkenyl groups (for example, vinyl group, 1-propenyl group, 2-propenyl group, 2-butenyl group, etc.), alkynyl groups having 1 to 6 carbon atoms (for example, acetylenyl group, 1-propynyl group, 2-propynyl) Group, 2-butynyl group, etc.), an alkoxy group having 1 to 6 carbon atoms (for example, methoxy group, ethoxy group, n-propoxy group, iso-propoxy group, n-butoxy group, t ert-butoxy group, etc.), C1-C6 alkylthio group (for example, methylthio group, ethylthio group, n-propylthio group, iso-propylthio group, n-butylthio group, tert-butylthio group, etc.), carbon number 6 -14 aryl group (for example, phenyl group, naphthyl group, anthracenyl group, etc.), C6-C10 aryloxy group (for example, phenoxy group, naphthoxy group, etc.), C6-C10 arylthio group (for example, phenylthio group, Naphthylthio group etc.), acyl group (eg acetyl group, propionyl group, trifluoroacetyl group, benzoyl group etc.), acyloxy group (eg acetoxy group, propionyloxy group, trifluoroacetoxy group, benzoyloxy group etc.), alkoxycarbonyl Group (methoxycarbonyl group, ethoxycarbonyl group) Group, such as tert- butoxycarbonyl group), hetero atom-containing aromatic Hajime Tamaki (such as furyl group having 4 to 8 carbon atoms, a thienyl group, etc.), a nitro group, a cyano group, and the like.

  Preferred examples of the substituent include a halogen atom, an alkyl group, an alkyloxy group, an aryl group, an aryloxy group, an arylthio group, and an acyl group.

  Of these substituents, possible ones may be further substituted.

X ⁻ represents a counter anion. Counter anions include complex ions such as BF ₄ ⁻ , B (C ₆ F ₅ ) ₄ ⁻ , PF ₆ −, AsF ₆ ⁻ , SbF ₆ ⁻ , p-CH ₃ C ₆ H ₄ SO ₃ ⁻ , CF _3. SO ₃ ^- sulfonate ion and the like. As the counter anion, borate ion and PF ₆ ^- are preferable because of their high acid generation ability.

  Specific examples of the sulfonium salt represented by the general formula (3) are shown below, but the present invention is not limited thereto.

《Actinic ray》
Examples of actinic rays used for such curing include ultraviolet rays and electron beams.

As the ultraviolet light source, a light source having an emission wavelength peak at 250 to 370 nm, more preferably 270 to 340 nm is preferable. A light source having an illuminance of 1 to 3000 mW / cm ² , more preferably 1 to 200 mW / cm ² is preferable.

  Examples of such light sources include mercury arc lamps, xenon arc lamps, fluorescent lamps, carbon arc lamps, tungsten-halogen copying lamps high pressure mercury lamps, metal halide lamps, electrodeless UV lamps, low pressure mercury lamps, UV lasers, xenon. Examples include, but are not limited to, flash lamps, insect traps, black lights, germicidal lamps, cold cathode tubes, LEDs, and the like. Further, when the second protective layer is formed by a plasma CVD method under atmospheric pressure or a pressure near atmospheric pressure described later, the second protective layer may be cured using ultraviolet light emitted from the plasma space.

  In addition, in the case of curing with an electron beam, curing is usually performed with an electron beam having an energy of 300 eV or less, but it is also possible to cure instantaneously with an irradiation amount of 1 to 5 Mrad.

<< second protective layer >>
It is preferable that a second protective layer made of a metal oxide, a metal nitride, or a metal oxynitride is further provided on the protective layer made of the organic-inorganic hybrid layer to further improve the durability. Providing the second protective layer further reduces the permeation of chemical degradation factors such as moisture and oxygen into the organic semiconductor layer, and the first protective layer containing the water-soluble polymer expands due to environmental humidity. -It can prevent contracting.

  Examples of metal oxides, metal nitrides or metal oxynitrides include silicon oxide, aluminum oxide, tantalum oxide, titanium oxide, tin oxide, vanadium oxide, barium strontium titanate, barium zirconate titanate, zirconate titanate Lead, lead lanthanum titanate, strontium titanate, barium titanate, barium fluoride magnesium, bismuth titanate, strontium bismuth titanate, strontium bismuth tantalate, bismuth tantalate niobate, yttrium trioxide, etc., Examples thereof include metal nitrides such as silicon nitride, aluminum nitride, boron nitride, and titanium nitride. Among these, silicon oxide, silicon nitride, and silicon oxynitride having low gas permeability are preferable. Most preferably, it is a silicon oxide which has a comparatively flexible property.

  As a method for forming these thin films, a method similar to that for forming the gate insulating layer described above can be used. However, it is preferable to form the thin film by an atmospheric pressure plasma CVD method.

<Atmospheric pressure plasma CVD method>
The second protective layer is preferably formed by a plasma CVD method (hereinafter also referred to as an atmospheric pressure plasma CVD method) under atmospheric pressure or a pressure near atmospheric pressure. In addition, in this invention, the atmospheric pressure vicinity represents the pressure of 20-110 kPa, More preferably, it is 70-140 kPa.

  As a method for forming the second protective film by plasma film formation under atmospheric pressure, JP-A-11-43781, JP-A-2003-179234, WO04 / 75279, JP-A-2005-15085 are described. It is described in the issue. Thereby, a highly functional thin film can be formed with high productivity. Among these, as described in Japanese Patent Application Laid-Open No. 2005-15085, a discharge gas is introduced into the discharge space under an atmospheric pressure or a pressure in the vicinity of the atmospheric pressure and excited to form a thin film in a mixed space outside the discharge space. It is preferable to use a method in which a thin film is formed by mixing with a gas to form a secondary excitation gas and exposing the secondary excitation gas to the substrate (first protective layer).

  It is estimated that when the discharge gas directly exposed to the discharge space and the thin film forming gas are mixed outside the discharge space, the thin film forming gas receives energy from the discharge gas excited in the discharge space and is indirectly excited. ing. In the present invention, this mixed gas is called a secondary excitation gas.

  Although the principle is not clear, when the thin film forming gas is indirectly excited, the second protective layer can be formed at a high performance and at a high speed as compared with the case where it is exposed directly to the discharge space. In the present invention, such a method is also called a jet method.

  The discharge space is a space which is sandwiched between electrode pairs arranged to face each other with a predetermined distance, and causes discharge by introducing a discharge gas between the electrode pairs and applying a voltage. The term “outside the discharge space” means a space that is not the discharge space.

  The form of the discharge space is not particularly limited, and may be, for example, a slit formed by a pair of opposed flat plate electrodes, or a space formed in a circumferential shape between two cylindrical electrodes.

  Next, an embodiment of an atmospheric pressure plasma processing apparatus, an atmospheric pressure plasma processing method, and an electrode system for an atmospheric pressure plasma processing apparatus used for a thin film forming method will be described below with reference to the drawings. It is not limited. In addition, the following explanation may include assertive expressions for terms and the like, but it shows preferred examples of the present invention, and the meaning and technical scope of the terms of the present invention are shown. It is not limited.

  FIG. 2 is a cross-sectional view showing an example of a jet type atmospheric pressure plasma processing apparatus.

  In FIG. 2, the atmospheric pressure plasma processing apparatus 1 mainly includes a high frequency between a counter electrode that is disposed so that a first electrode 2 and a second electrode 3 face each other, and a counter electrode that is a voltage applying unit 4. In addition to the high-frequency power source 5 for applying an electric field, although not shown, a gas supply means for introducing a discharge gas into the discharge space and a thin film forming gas outside the discharge space, an electrode temperature adjusting means for controlling the electrode temperature, etc. It is configured.

  A region A that is sandwiched between the first electrode 2 and the second electrode 3 and has a dielectric shown by hatching on the first electrode is a discharge space. A discharge gas G is introduced into the discharge space A to excite the discharge gas. Further, the thin film forming gas M is introduced into a region where the discharge is not performed separately from the region where the electrodes are installed. Next, the excited discharge gas G ′ and the thin film forming gas M are mixed in the region of the mixed space B outside the discharge space where no electrode is present to form a secondary excitation gas N. A thin film is formed by exposing to the surface of the material 8. In the present invention, the thin film forming gas can be sufficiently indirectly excited by mixing the excitation gas and the thin film forming gas in the apparatus.

  In addition, the base material 8 can process not only a sheet-like base material like a support body but various sizes and shapes. For example, a thin film can be formed on a substrate having a shape such as a lens shape or a spherical shape.

  The pair of counter electrodes (the first electrode 2 and the second electrode 3) is composed of a metal base material and a dielectric 7, and by combining the metal base material to cover a dielectric having an inorganic property, Further, it may be constituted by a combination in which a ceramic material is sprayed on a metal base material and then a dielectric material sealed with a substance having an inorganic property is coated. As the metal base material, metals such as titanium, copper, gold, silver, platinum, stainless steel, aluminum, and iron can be used, but stainless steel or titanium is preferable. Dielectric lining materials include silicate glass, borate glass, phosphate glass, germanate glass, tellurite glass, aluminate glass, vanadate glass, etc. Of these, borate glass is preferable because it is easy to process. As the ceramic used for the thermal spraying of the dielectric, alumina is preferable, and it is preferable to perform a sealing treatment with silicon oxide or the like. Further, as the sealing treatment, the alkoxysilane-based sealing material can be made inorganic by a sol-gel reaction.

  In FIG. 2, the pair of counter electrodes are flat electrodes like the first electrode 2 and the second electrode 3, but one or both electrodes may be hollow cylindrical electrodes or prismatic electrodes. . The high-frequency power source 5 is connected to one electrode (for example, the first electrode 2) of the pair of counter electrodes, and the other electrode (for example, the second electrode 3) is grounded by the earth 9, and the pair of counter electrodes An electric field can be applied between them.

  The voltage applying means 4 applies a voltage from the high frequency power source 5 to the metal pair of each electrode. There is no particular limitation on the high-frequency power source. As a high-frequency power source that can be used for forming the inorganic thin film (second protective layer), a high-frequency power source (50 kHz) manufactured by Shinko Electric, a high-frequency power source manufactured by HEIDEN Laboratory (continuous mode use, 100 kHz), a high-frequency power source manufactured by Pearl Industries (200 kHz ), Pearl Industrial High Frequency Power Supply (800 kHz), Pearl Industrial High Frequency Power Supply (2 MHz), JEOL High Frequency Power Supply (13.56 MHz), Pearl Industrial High Frequency Power Supply (27 MHz), Pearl Industrial High Frequency Power Supply (150 MHz), etc. It can be preferably used. Alternatively, a power source that oscillates at 433 MHz, 800 MHz, 1.3 GHz, 1.5 GHz, 1.9 GHz, 2.45 GHz, 5.2 GHz, or 10 GHz may be used.

The frequency of the high frequency electric field applied between the counter electrodes when forming the inorganic thin film (second protective layer) is not particularly limited, but is preferably 0.5 kHz or more and 2.45 GHz or less as the high frequency power source. Moreover, the electric power supplied between counter electrodes becomes like this. Preferably it is 0.1 W / cm < ² > or more, Preferably it is 50 W / cm < ² > or less. Note that the voltage application area (cm ² ) in the counter electrode refers to the area where discharge occurs. The high-frequency voltage applied between the counter electrodes may be an intermittent pulse wave or a continuous sine wave.

  Further, an electric field may be applied between the electrodes by two or more high-frequency power supplies to form a discharge space.

  The distance between the counter electrodes is determined in consideration of the thickness of the dielectric on the metal base material of the electrodes, the magnitude of the applied voltage, the purpose of using plasma, and the like. The shortest distance between the dielectric when the dielectric is placed on one of the electrodes and the distance between the dielectrics when the dielectric is placed on both of the electrodes is the distance between the electrodes. From the viewpoint of discharging, it is preferably 0.1 to 20 mm, more preferably 0.2 to 10 mm.

  Before forming the inorganic thin film (second protective layer), the substrate or the first protective layer may be exposed to the discharge space or the excitation gas to perform surface treatment of the substrate. For example, when the raw material is an alkoxide, a hydrophilic treatment by exposure to a discharge space or an excitation gas is preferably used. Further, before the thin film is formed, the surface of the base material may be previously neutralized and dust may be further removed. As the charge removal means and the dust removal means after the charge removal process, the same means as those used in the above apparatus can be employed. Although not shown in the drawing, as a charge removal means, besides a normal blower type or contact type, a plurality of positive and negative ion generation charge removal electrodes and a charge removal device in which an ion attracting electrode is opposed to sandwich the substrate, and then positive / negative Alternatively, a high-density static elimination system (Japanese Patent Laid-Open No. 7-263173) provided with the above-described DC type static elimination device may be used. Examples of the dust removal means after the charge removal treatment include a non-contact type jet-type depressurization type dust removal device (Japanese Patent Laid-Open No. 7-60211) and can be preferably used, but are not limited thereto.

  FIG. 3 is a cross-sectional view showing another example of a jet-type atmospheric pressure plasma processing apparatus according to the present invention.

  In FIG. 3, the atmospheric pressure plasma processing apparatus 1 is mainly a counter electrode and voltage applying means 4 arranged so that the first electrodes 2, 2 ′ and the second electrodes 3, 3 ′ face each other. In addition to the high-frequency power source 5 that applies a high-frequency electric field between the opposing electrodes, although not shown in the drawing, it is constituted by gas supply means, electrode temperature adjustment means, and the like.

  A discharge gas G is introduced into a region where the first electrode 2 and the second electrode 3 or the first electrode 2 'and the second electrode 3' are opposed to each other and excited in the discharge spaces A and A '. A thin film forming gas M containing an organometallic compound substituted with an organic group having a fluorine atom is introduced into a region where the second electrodes 3 and 3 ′ are opposed to each other. Next, in the region of the mixed space B outside the discharge space where there is no counter electrode, the excited discharge gas G ′ and the thin film forming gas M are mixed to form a secondary excitation gas. A thin film is formed by exposing to the surface of the material 8.

  A discharge gas G is introduced into a region where the first electrode 2 and the second electrode 3 or the first electrode 2 'and the second electrode 3' are opposed to each other and excited in the discharge spaces A and A '. A thin film forming gas M containing an organometallic compound substituted with an organic group having a fluorine atom is introduced into a region where the second electrodes 3 and 3 ′ are opposed to each other. Next, in the region of the mixed space B outside the discharge space where there is no counter electrode, the excited discharge gas G ′ and the thin film forming gas M are mixed to form a secondary excitation gas. A thin film is formed by exposing to the surface of the material 8.

  FIG. 4 is an example of an atmospheric pressure plasma processing apparatus. The discharge gases G and G ′ are introduced from the discharge gas inlets 13 and 13 ′, and gas excitation is performed in the discharge spaces A and A ′. The excited gas is injected onto the base material 8 from the lower part of the apparatus, and is similarly injected. The thin film forming gas M is brought into contact, and the thin film forming gas is indirectly excited to form a thin film.

  By using an apparatus exemplified by these, the second protective film can be formed.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

Example 1
<< Production of organic thin film transistor >>
The following electroless plating catalyst solution is used as an ink on an n-type Si wafer having a specific resistance of 0.02 Ω · cm having a silicon oxide film with a thickness of 200 nm formed by thermal oxidation, and a bias voltage of 2000 V is applied to the support base. A voltage was applied, and a pulse voltage (400 V) was further superimposed to eject ink according to the source and drain electrode patterns. The inner diameter of the nozzle outlet was 10 μm, and the gap between the nozzle outlet and the substrate was kept at 500 μm. The following prescription was used as the plating catalyst-containing ink.

(Electroless plating catalyst solution)
Soluble palladium salt (palladium chloride, Pd ²⁺ concentration 1.0 g / L) 20% by mass
Isopropyl alcohol 12% by mass
Glycerin 20% by mass
2-Methyl-pentanethiol 5% by mass
1,3-butanediol 3% by mass
Ion exchange water 40% by mass
Furthermore, a catalyst pattern was formed by drying and fixing.

  Next, printing was performed on the region including the region where the plating catalyst pattern was formed by using the following electroless gold plating solution as an ink by a screen printing method. When the plating agent was in contact with the plating catalyst, the gold thin film was deposited only on the plating catalyst pattern.

(Electroless gold plating solution)
Dicyano gold potassium 0.1 mol / L
Sodium oxalate 0.1 mol / L
Sodium potassium tartrate 0.1mol / L
The substrate surface on which the gold thin film was dissolved was thoroughly washed with pure water and dried to form a source / drain electrode pattern made of gold. The source / drain electrodes were fabricated so that the channel length L was 25 μm and the channel width W was 250 μm.

  Next, the Si wafer on which the source / drain electrodes are formed is subjected to a vacuum oxygen plasma treatment for 60 seconds under conditions of an oxygen flow rate of 50 sccm, a degree of vacuum of 10 Pa, and an output of 200 W using a dry etching apparatus DEM-451 manufactured by Anelva Corporation. The surface of the source / drain electrode was cleaned.

  The surface of the source / drain electrode is subjected to surface treatment by immersing a Si wafer with a cleaned surface of the source / drain electrode in a 10 mmol / L ethanol solution of pentafluorobenzenethiol at room temperature for 30 minutes, rinsing with ethanol and drying. went.

  Next, the following organic semiconductor material 1 as a p-type organic semiconductor material is dissolved in toluene at a concentration of 0.5% by mass, and this solution is formed into a substantially circular shape having a diameter of about 300 μm using a microinjector IM300 manufactured by Narishige. After being applied and dried at room temperature, an organic semiconductor layer was formed by performing heat treatment at 90 ° C. for 1 minute in a nitrogen gas atmosphere. At this time, the film thickness of the organic semiconductor layer was 30 nm.

  Subsequently, the protective layer was formed with the following method and the organic thin-film transistors 11-17 were produced.

(Preparation of organic thin film transistor 11)
After forming the protective layer by applying the following protective layer solution 1 on the organic semiconductor layer produced above by spin coating at 3000 rpm for 1 minute, a high pressure mercury lamp is irradiated with energy of 150 mJ / cm ² through a mask, Pattern exposure was performed.

  After the exposure, ultrasonic cleaning with pure water for 10 minutes is performed three times, the protective layer of the unexposed portion is removed, and then drying is performed at 40 ° C. for 30 minutes and then at 60 ° C. for 30 minutes. Produced.

<Protective layer solution 1>
An aqueous solution containing 10% by mass of polyvinyl alcohol and 0.05% by mass of ammonium bichromate was designated as protective layer solution 1.

(Preparation of organic thin film transistor 12)
In the production of the organic thin film transistor 11, an organic thin film transistor 12 was produced in the same manner except that the protective layer solution 1 was replaced with Biosurfine-AWP (protective layer solution 2) manufactured by Toyo Gosei Co., Ltd.

(Preparation of organic thin film transistor 13)
In the production of the organic thin film transistor 11, the protective layer was formed in the same manner except that a protective layer was formed by vapor deposition of parylene (polyparaxylylene resin) using a CVD apparatus DACS-LAB manufactured by Kishimoto Sangyo Co., Ltd. Thus, an organic thin film transistor 13 was produced.

(Preparation of organic thin film transistor 14)
The following protective layer solution 4 was formed in a predetermined pattern using an ink jet printer, and then dried at 40 ° C. for 10 minutes.

  After drying, the substrate is ultrasonically washed with a dilute hydrochloric acid aqueous solution adjusted to pH 3 for 30 minutes, and then ultrasonically washed with pure water for 10 minutes three times to remove the protective layer of the unexposed portion, and then at 40 ° C. for 30 minutes. The organic thin-film transistor 14 was produced by performing drying for 30 minutes at 60 ° C. for 30 minutes.

<Protective layer solution 4>
To a mixed solution of 2.5 parts by mass of trimethoxysilane and 6.9 parts by mass of methanol maintained at 10 ° C., 0.6 part by mass of a 0.1% by mass aqueous trifluoroacetic acid solution was added dropwise, and then at room temperature 30 Stirring was carried out for a minute to carry out hydrolysis reaction of alkoxysilane.

  This solution was mixed with 90 parts by mass of a 10% by mass aqueous solution of polyvinyl alcohol, and a solution obtained by stirring at room temperature for 30 minutes was designated as protective layer solution 4.

(Preparation of organic thin film transistor 15)
In the production of the organic thin film transistor 14, an organic thin film transistor 15 was produced in the same manner except that 2.5 parts by mass of trimethoxysilane in the protective layer solution 4 was replaced with 2.0 parts by mass of methyltrimethoxysilane.

(Preparation of organic thin film transistor 16)
In the production of the organic thin film transistor 11, an organic thin film transistor 16 was produced in the same manner except that the protective layer solution 1 was replaced with the protective layer solution 6 described below.

<Protective layer solution 6>
Tetrakis (methoxyethoxy) silane 5.5 parts by mass, polyvinyl alcohol 9.0 parts by mass, Adekaoptomer SP152 (triphenylsulfonium salt, manufactured by Asahi Denka Co., Ltd.) 0.3 parts by mass, and pure water 85.2 parts by mass are mixed. The aqueous solution thus obtained was designated as protective layer solution 6.

(Preparation of organic thin film transistor 17)
In the production of the organic thin film transistor 16, an organic thin film transistor 17 was produced in the same manner except that the polyvinyl alcohol in the protective layer solution 5 was replaced with gelatin.

<< Evaluation of organic thin film transistor >>
About the obtained organic thin-film transistor, the carrier mobility before and behind a durability test was evaluated by the following method.

(Carrier mobility before durability test)
For the organic thin film transistor, the carrier mobility was calculated from the saturation region of the IV characteristic when the drain bias was −50 V and the gate bias was swept from −50 V to 0 V.

(Carrier mobility before durability test)
For the organic thin film transistor, after repeating the temperature and humidity change cycle of storing in an environment of 30 ° C. and 80% RH for 6 hours and in a temperature of 20 ° C. and 20% RH for 6 hours, similarly to the carrier mobility before the durability test Carrier mobility was evaluated.

  The results of evaluation are shown in Table 1.

  As can be seen from Table 1, in the durability test, the organic thin film transistor of the present invention has a decrease of about one digit, whereas the organic thin film transistor of the present invention shows a decrease of about two digits of the carrier mobility. It can be seen that the protective layer according to the present invention has a high protective ability.

Example 2
<< Production of organic thin film transistor >>
In order to obtain a higher protective effect, an organic thin film transistor was produced in which a second protective layer was formed on the protective layer (first protective layer) produced in Example 1. For comparison, an organic thin film transistor in which a protective layer made of an inorganic material was directly formed on the organic semiconductor layer was also produced.

(Preparation of organic thin film transistor 20)
A protective layer made of SiO ₂ was laminated 50 nm directly on the organic semiconductor layer of the organic thin film transistor element produced in Example 1 using a known sputtering technique, to produce an organic thin film transistor 20.

(Preparation of organic thin film transistors 21 to 27)
A first protective layer of an organic thin film transistor 11 - 17 prepared in Example 1, a protective layer made of SiO ₂ and 50nm laminated by a known sputtering technique, respectively to manufacture an organic thin film transistor 21-27.

(Preparation of organic thin film transistor 28)
An organic thin film transistor 28 was produced in the same manner as in the production of the organic thin film transistor 26 except that the organic semiconductor material 1 was replaced with the organic semiconductor material 2.

(Preparation of organic thin film transistor 29)
In the production of the organic thin film transistor 28, the organic thin film transistor 29 was produced in the same manner except that the method for forming the second protective layer was changed to the method for forming the SiO ₂ film by the atmospheric pressure plasma method described below.

<Atmospheric pressure plasma method>
In the atmospheric pressure plasma treatment, an SiO ₂ thin film was formed using an atmospheric pressure plasma treatment apparatus shown in FIG.

The discharge gas G introduced from the discharge gas introduction port 13 is gas type A, the discharge gas G introduced from the discharge gas introduction port 13 ′ is gas type B, and the thin film formation gas introduced from the thin film formation gas introduction port 15. A gas species C was used as M, and a SiO ₂ thin film was formed on the substrate 8. The film formation was performed by scanning the substrate in the horizontal direction in the figure.

<Gas type A: Discharge gas>
Nitrogen gas 98.5% by volume
Hydrogen gas 1.5% by volume
<Gas type B: Discharge gas>
Nitrogen gas 98.5% by volume
Hydrogen gas 1.5 volume%
<Gas type C: Thin film forming gas>
Nitrogen gas 99.9% by volume
Tetraethoxysilane 0.1% by volume
The above compound was vaporized in nitrogen gas by a vaporizer manufactured by STEC.

<Gas supply ratio>
Gas species A: Gas species B: Gas species C = 1: 1: 1 (volume ratio) were supplied.

  For the electrodes 2, 2 ', 3 and 3', a stainless steel SUS316 is used for the electrode, and further, the surface of the electrode is spray-coated with alumina ceramic to 1 mm, and then an alkoxysilane monomer is dissolved in an organic solvent. Was applied to an alumina ceramic coating and dried, followed by heating at 150 ° C. and sealing treatment to form a dielectric. The portion of the electrode not covered with the dielectric was connected to the high frequency power source 5 or grounded 9.

A discharge power of 7 W / cm ² was applied to the high-frequency power source 5 with a high-frequency power source (40 kHz) manufactured by HEIDEN Laboratory. The distance between the gas outlet 16 and the substrate was 2 mm. As the base material 8, 0.5 t soda lime glass (single side polishing) made of Japanese plate glass having a width of 10 mm, a length of 10 mm and a thickness of 0.5 mm was used.

  The constitutional contents of the organic thin film transistors 20 to 27 are shown in Table 2 below.

<< Evaluation of organic thin film transistor >>
About the obtained organic thin-film transistor, it carried out similarly to Example 1, and evaluated the carrier mobility before and behind a durability test.

  Moreover, the following method evaluated the adhesiveness of the 2nd protective layer.

<Adhesion test>
As an evaluation of adhesion, a cross-cut test based on JIS K5400 was performed. For the surface on which the second protective layer is formed (the portion where the first protective layer and the second protective layer are formed directly on the insulating layer, not on the organic semiconductor layer, the source electrode, and the drain electrode), Eleven incisions of 90 ° with respect to the surface of a single-edged razor blade were inserted vertically and horizontally at intervals of 1 mm to produce 100 1 mm square grids. A commercially available cellophane tape was affixed on this, and one end of the tape was peeled vertically by hand, and the ratio of the peeled area of the thin film to the affixed tape area from the score line was evaluated according to the following criteria.

◯: The peeled area ratio is less than 10%. Δ: The peeled area ratio is 10% or more and less than 25%. X: The peeled area ratio is 25% or more.

  As can be seen from Table 3, in the organic thin film transistor 20 in which the second protective layer is formed directly on the organic semiconductor layer, the carrier mobility is greatly reduced from the beginning due to damage during the formation of the second protective layer.

  Moreover, the comparative organic thin-film transistors 21-23 are inferior in adhesiveness with the 2nd protective layer which consists of an inorganic thin film, and the carrier mobility after a durability test is seen a 1-digit fall.

  On the other hand, the organic thin film transistors 24-29 of the present invention have high adhesiveness of the second protective layer, and the mobility after the durability test is maintained at a value of 60% or more, and it is confirmed that the organic thin film transistors have high protective ability. It was.

It is sectional drawing which shows the layer structural example of an organic thin-film transistor. It is sectional drawing which shows an example of a jet-type atmospheric pressure plasma discharge processing apparatus. It is sectional drawing which shows another example of a jet system atmospheric pressure plasma discharge processing apparatus. It is sectional drawing which shows another example of a jet system atmospheric pressure plasma discharge processing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Atmospheric pressure plasma discharge processing apparatus 2, 2 '1st electrode 3, 3' 2nd electrode 4 Voltage application means 5 High frequency power supply 6 Gas control board 7, 7 'Dielectric 8 Base material 9 Ground 13, 13' Discharge gas introduction Port 15 Thin film forming gas inlet 16 Gas outlet G Discharge gas G ′ Excited discharge gas M Thin film forming gas N Secondary excited gas A Discharge space B Mixed space 101 Organic semiconductor film 102 Source electrode 103 Drain electrode 104 Gate electrode 105 Gate insulation Layer 106 substrate

Claims (12)

An organic thin film transistor having a gate electrode, a gate insulating film, an organic semiconductor layer made of an organic semiconductor material, a source electrode and a drain electrode, and hydrolyzing a water-soluble polymer and an alkoxysilane represented by the following general formula (1) An organic thin film transistor comprising a protective layer made of an organic-inorganic hybrid layer containing a polycondensate on the organic semiconductor layer.
General formula (1) R _4-n Si (OR ′) _n
Wherein R represents a hydrogen atom or a substituent selected from an alkyl group, a halogenated alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an aryl group, a heteroaryl group, an alkylsilyl group and a carbonyl group; Represents a hydrogen atom or an alkyl group, and n represents an integer of 2 to 4.) 1-30 mass% of inorganic polymer compounds represented by the following general formula (2) obtained by hydrolytic polycondensation of the alkoxysilane represented by the general formula (1) to the organic-inorganic hybrid layer. The organic thin film transistor according to claim 1, which is contained.
General formula (2) R _4-n SiO _{n / 2}
(In the formula, R represents a hydrogen atom or a substituent selected from an alkyl group, a halogenated alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an aryl group, a heteroaryl group, and an alkylsilyl group, and n represents 2 to 4) Represents an integer.) The organic thin film transistor according to claim 1 or 2, wherein in the general formula (1) and the general formula (2), n = 4. The water-soluble polymer is polyvinyl alcohol, halogenated polyvinyl alcohol, polyvinyl acetal, polyvinyl butyral, polyvinyl pyrrolidone, copolymers thereof, alkyl cellulose, hydroxyalkyl cellulose, cellulose ester, starch and derivatives thereof, gelatin, casein, albumin The organic thin film transistor according to any one of claims 1 to 3, wherein the organic thin film transistor is a water-soluble polymer selected from natural rubber and a mixture thereof. The organic thin film transistor according to claim 4, wherein the water-soluble polymer is polyvinyl alcohol. The organic thin film transistor according to any one of claims 1 to 5, wherein the protective layer is formed by applying and drying an aqueous solution containing at least 50% by mass or more of water. After forming the protective layer containing the water-soluble polymer, the alkoxysilane represented by the general formula (1) and the photoacid generator, the pattern is exposed to actinic rays to generate an acid in the exposed area. The organic thin film transistor according to any one of claims 1 to 6, wherein an organic-inorganic hybrid layer is formed only in an exposed portion with the acid. The organic thin film transistor according to claim 7, wherein the photoacid generator is a sulfonium salt compound. 9. The method according to claim 1, further comprising a second protective layer made of a metal oxide, a metal nitride, or a metal oxynitride on the protective layer made of the organic-inorganic hybrid layer. The organic thin-film transistor as described. The organic thin film transistor according to claim 9, wherein the second protective layer is a protective layer made of silicon oxide. The organic thin film transistor according to claim 9 or 10, wherein the second protective layer is formed by a plasma CVD method under an atmospheric pressure or a pressure near atmospheric pressure. The organic thin film transistor according to claim 1, wherein the organic semiconductor layer is formed by coating using a non-aqueous solvent.

Images