JP2008153259A - Organic thin-film transistor, and its fabrication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic thin-film transistor which can be fabricated by a solution process with a high production efficiency, exhibiting high solution resistance after formation and having a gate insulating film formed with a uniform film thickness, and to provide its fabrication method. <P>SOLUTION: The organic thin-film transistor comprises a gate electrode pattern, a gate insulation layer, a source electrode pattern, a drain electrode pattern, and a semiconductor layer containing an organic semiconductor material formed on a substrate wherein the gate insulation layer contains gelatin bridged by a hardening agent. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an organic thin film transistor and a method for manufacturing the organic thin film transistor.

  With the widespread use of information terminals, there is an increasing need for flat panel displays (FPDs) 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 display device, a display medium is formed using an element using liquid crystal, an organic electroluminescence element (hereinafter also referred to as an organic EL element), 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 thin film transistor elements are formed on a glass substrate, and a desired image is displayed on the display by controlling a voltage or current applied to a pixel portion such as a liquid crystal or an organic EL element.

  The semiconductor layer is formed in contact with the gate insulating film, and a gate electrode is formed on the other surface of the gate insulating film. A charge amount corresponding to the electric field applied to the gate electrode can be generated at the interface between the insulating layer and the semiconductor layer. As a result, the conductivity of the semiconductor layer can be changed. That is, the amount of current flowing from the source electrode to the drain electrode through the semiconductor layer can be controlled by the electric field applied to the gate electrode.

  For this reason, if the thickness of the insulating layer is not constant, the amount of charge induced in the semiconductor layer, that is, the value of the current flowing between the source and drain electrodes varies. In addition, if there is an extremely thin part of the gate insulating layer, the concentration of the electric field may occur and the gate insulating layer may be destroyed. Therefore, the gate insulating layer is formed uniformly with high accuracy. Need to be done.

  As materials for forming the constituent elements of conventional transistors, various metals are used for electrodes, various metal oxides are used for insulating layers, and a-Si (amorphous silicon) and p-Si are mainly used for semiconductor layers. A semiconductor such as (polysilicon) is generally used.

  Formation of these Si semiconductor, metal oxide and metal layers usually requires sputtering, plasma CVD or other vacuum manufacturing processes. Furthermore, in these methods, the pattern shape cannot be directly formed. Therefore, after forming a layer on the entire surface, the pattern is formed by a process that requires many steps such as photolithography.

  A conventional TFT element is manufactured by repeatedly forming such a layer by a vacuum process and patterning having complicated steps to form each layer.

  For this reason, in the conventional TFT element manufacturing method, the apparatus cost and running cost are very large. Furthermore, to meet the needs for larger display screens and higher definition, it is necessary to make major design changes to the manufacturing equipment, such as changing the vacuum chamber size and mask pattern, and the reduction in manufacturing costs is approaching its limit. It is coming.

  In addition, since the formation of the Si-based semiconductor layer includes a process at a high temperature, the base material is restricted to be a material that can withstand the process temperature. Therefore, the TFT substrate is practically limited to glass. .

  When a thin display such as the electronic paper or digital paper described above is configured using a conventional TFT element, the display is heavy, lacks flexibility, and can be broken by a drop impact. . These characteristics resulting from the formation of Si-based TFT elements on a glass substrate are undesirable in satisfying the need for an easy-to-carry-type thin display with the progress of computerization.

  Therefore, in recent years, studies on organic thin film transistor elements using organic semiconductor materials for semiconductor layers have become active. Examples of such organic semiconductor materials include acenes such as pentacene and tetracene, compounds having substituents introduced therein, phthalocyanines and porphyrins, precursors thereof, low molecular compounds such as perylene and its tetracarboxylic acid derivatives, Aromatic oligomers typically represented by thiophene hexamers called α-thienyl or sexithiophene, naphthalene, anthracene, a compound in which a 5-membered aromatic heterocyclic ring is condensed symmetrically, mono-, oligo- and polydithienopyridines, and further polythiophene, Examples thereof include conjugated polymers such as polythienylene vinylene and poly-p-phenylene vinylene.

  If the semiconductor layer can be formed of these organic semiconductor materials, it can be manufactured by a solution process such as vacuum or low-pressure deposition at low temperature or coating. 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.

  Above all, if patterning can be performed by a simple solution process such as an ink jet method or a printing method, a number of steps such as exposure, development, and washing associated with photolithography can be reduced, and a display can be manufactured in a simple process, resulting in a manufacturing cost. It is expected that a significant reduction of

  Similarly, a material that can be easily processed without using a vacuum process has been studied for the gate insulating layer. For example, a method of forming an inorganic thin film by coating by the sol-gel method or a method of forming an insulating organic polymer by coating has been studied. In order to obtain a thin film having high insulation by the sol-gel method, a high temperature is required. Heat treatment is necessary and it is not suitable for the purpose of forming on a plastic substrate.

  In addition, studies have been made to form a gate insulating layer by applying and drying organic polymers such as polyvinylphenol, polyvinyl alcohol, and polyimide. However, since the insulating property is low, the durability is low or the insulating property is low. A thick film thickness is required to increase the transistor driving voltage, or the gate insulating layer dissolves during the solution process in the next process (for example, formation of an organic semiconductor layer) and the characteristics deteriorate. There was a problem.

  Although some polyimides report that TFTs can be driven with a relatively thin film, polyimide is generally an insoluble polymer material, and after applying a precursor polyamic acid solution, it is also subjected to high-temperature heat treatment. Since it is necessary to convert it to polyimide, it is necessary to use expensive engineering plastic in order to form it on a plastic substrate, which may be more expensive than using a glass substrate, which is not preferable.

  In recent years, attempts have been made to increase the insulation, reliability, and solvent resistance of a gate insulating layer made of an organic polymer by applying a cross-linking reaction after applying the organic polymer.

  For example, a gate insulating film in which a phenol resin is crosslinked with a melamine-based crosslinking agent is disclosed (for example, see Patent Document 1). Further, an organic thin film transistor is disclosed in which a polyvinylphenol containing a photoacid generator and a crosslinking agent is irradiated with ultraviolet light to form the crosslinked polyvinylphenol as a gate insulating layer (see, for example, Patent Document 2). .)

  Moreover, the gate insulating layer crosslinked by irradiating the gate insulating layer made of polyvinylphenol and poly (N- (hydroxyphenyl) maleimide) copolymer containing a photoacid generator and a crosslinking agent with ultraviolet light. An organic thin film transistor having the above has been disclosed (for example, see Patent Document 3).

  Furthermore, there is disclosed a gate insulating film made of a crosslinked polymer by utilizing a dimerization reaction of a cinnamic acid site caused by irradiating a thin film made of polyvinyl cinnamate with ultraviolet light (for example, (See Patent Document 4).

  However, in Patent Document 1 above, baking at a high temperature such as 180 ° C. is necessary for the completion of the crosslinking reaction, and it is difficult to form on a general-purpose plastic film. The temperature required for forming the gate insulating layer is reduced to the range of 140 ° C. to room temperature by using the gate insulating layer, but the coating method of the gate insulating layer is spin coating, which is continuously applied to a large-area substrate. There was a problem that it was not realistic as a method.

  In addition, since the concentration of the solution to be applied is low and low in viscosity, if there is a disturbance such as vibration or air current before the solvent volatilizes, the film thickness tends to fluctuate, resulting in large variations in the resulting organic thin film transistor elements. Therefore, it has been difficult to obtain an organic thin film transistor element with little variation between elements.

Thus, a gate insulating layer that can be formed by a simple coating process without using a vacuum process and a high-temperature process, and has a high solvent resistance and a uniform film thickness after formation. The materials that can be formed and the manufacturing methods are still unknown.
JP-A-2005-354012 International Publication No. 05-23876 Pamphlet US Patent Application Publication No. 2005-127355 JP 2005-303270 A

  An object of the present invention is to provide an organic thin film transistor having a gate insulating layer formed with a uniform film thickness and an organic thin film transistor that can be manufactured by a solution process with high production efficiency, has high solvent resistance after formation, and organic It is to provide a method for manufacturing a thin film transistor.

  The above object of the present invention has been achieved by the following configurations 1 to 15.

1. In an organic thin film transistor having a semiconductor layer containing at least a gate electrode pattern, a gate insulating layer, a source electrode pattern, a drain electrode pattern, and an organic semiconductor material on a substrate,
An organic thin film transistor, wherein the gate insulating layer contains gelatin crosslinked by a hardener.

  2. 2. The organic thin film transistor according to 1 above, wherein the gate insulating layer is surface-treated using a compound represented by the following general formula (1).

General formula (1)
A-R ₁
[Wherein, A is an aldehyde group, N-methylol group, epoxy group, alkylcarbonyloxycarbonyl group, arylcarbonyloxycarbonyl group, halogen-substituted carbonyl group, vinylsulfonyl group, acryloylamino group, methacryloylamino group, ethyleneimine-2 - yl group, an alkyl carbodiimide group, an aryl carbodiimide group, isoxazolyl group, an alkoxysilyl group, a halogenated silyl group, a functional group capable of forming a bond by reacting with an amino group, R ₁ is an alkyl group, a cycloalkyl An alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heteroaryl group or an alkylsilyl group is represented. ]
3. 3. The organic thin film transistor as described in 1 or 2 above, wherein A is a vinylsulfonyl group.

  4). 4. The organic thin film transistor according to any one of 1 to 3, wherein the gate insulating layer is surface-treated using a compound represented by the following general formula (2).

[In the formula, L represents an alkylene group, a cycloalkylene group, an alkenylene group, an alkynylene group or an arylene group, Q represents C, Si, Ge, Sn or Pb, and R _{2 to} R ₄ each represents an alkyl group, It represents a cycloalkyl group, an aryl group, a heteroaryl group or an alkylsilyl group, and may be linked to each other to form a ring. ]
5. 5. The organic thin film transistor according to any one of 1 to 4, wherein the Q represents Si.

  6). A bottom contact structure is formed in which a gate electrode pattern, a gate insulating layer, a source electrode pattern, a drain electrode pattern, and a semiconductor layer containing an organic semiconductor material are stacked in this order on the substrate. The organic thin film transistor according to any one of 1 to 5 above.

  7. The source electrode pattern and the drain electrode pattern are electrode patterns formed through an exposure process, a development process, and a plating process on a photosensitive layer in which silver salt particles are dispersed in a binder resin. 7. The organic thin film transistor according to any one of 1 to 6 above.

  8). 8. The organic thin film transistor as described in 7 above, wherein the binder resin is gelatin.

  9. 9. The organic thin film transistor as described in 7 or 8 above, wherein the silver salt grains are silver halide grains.

  10. 10. The organic thin film transistor according to any one of 7 to 9, wherein the metal formed by the plating process is gold.

  11. 11. The organic thin film transistor according to any one of 1 to 10 above, wherein the organic semiconductor material is a pentacene derivative.

12 In manufacturing the organic thin film transistor according to any one of 1 to 11,
(A) forming a photosensitive layer in which silver salt particles are dispersed in gelatin on a gate electrode pattern by coating;
(B) a step of obtaining a metallic silver pattern through an exposure step and a development treatment on the photosensitive layer;
(C) A step of forming a source electrode pattern and a drain electrode pattern through a plating process on the metal silver pattern,
A method for producing an organic thin film transistor, comprising:

  13. 13. The method for producing an organic thin film transistor as described in 12 above, which comprises a step of surface-treating the surface of the gate insulating layer with the compound represented by the general formula (1) or (2).

  14 14. The method for producing an organic thin film transistor according to 12 or 13, wherein the plating process includes a gold plating process.

  15. 15. The method for producing an organic thin film transistor according to any one of 12 to 14, further comprising a step of forming a semiconductor layer containing the organic semiconductor material by coating.

  According to the present invention, since a gate insulating layer can be formed with a uniform thickness, an organic thin film transistor having thin film transistor characteristics with little variation between elements can be obtained. In addition, an organic thin film transistor that can be formed on a plastic film with high production efficiency without using a vacuum process, a photolithographic process, a high-temperature heat treatment process, and the like, and a method for manufacturing the same were provided.

  In the present invention, the structure defined in any one of claims 1 to 10 has excellent transistor characteristics such as high carrier mobility, good ON / OFF characteristics, and low threshold voltage. It was possible to provide an organic thin film transistor, and to provide a method for producing the organic thin film transistor.

  Hereinafter, details of each component according to the present invention will be described.

  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 according to 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. The organic thin film transistor of the present invention may be any of the top gate type, the bottom gate type, the top contact type, and the bottom contact type, and can be selected according to the use of the organic thin film transistor.

  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 2 and a drain electrode 3 are provided on a base 6, and an organic semiconductor film 1 is formed thereon. Further, the gate insulating layer 5 is formed in contact with the organic semiconductor film 1, and the source electrode 4 is provided thereon.

  FIG. 1B shows an example of a layer structure of a top gate / top contact type. A substrate 6 has a gate electrode 4 on which a gate insulating layer 5 is formed. The organic semiconductor film 1 is formed thereon, and the source electrode 2 and the drain electrode 3 are formed in contact with the organic semiconductor film 1.

  FIGS. 1D and 1F show an example of a bottom gate / bottom contact type layer structure. A substrate 6 has a gate electrode 4 on which a gate insulating layer 5 is formed. The source electrode 2 and the drain electrode 3 are formed thereon, and the organic semiconductor film 1 is formed thereon.

  FIG. 1E shows an example of a layer structure of a bottom gate / top contact type. A substrate 6 has a gate electrode 4 on which a gate insulating layer 5 is formed. The organic semiconductor film 1 is formed thereon, and the source electrode 2 and the drain electrode 3 are formed thereon.

  More preferably, the organic thin film transistor of the present invention has a bottom-gate / bottom-contact type structure shown in FIGS.

  Since the organic semiconductor material may be deteriorated by oxygen, moisture, heat, or the like, the damage in forming other layers can be reduced by forming it in the latter half of the process as much as possible.

  From this point of view, the bottom gate / bottom contact type element can form the organic semiconductor layer in the second half of the process, so that an organic thin film transistor having good characteristics with little deterioration can be obtained.

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

<Gate insulation layer>
The gate insulating layer according to the organic thin film transistor of the present invention will be described.

  In the present invention, the fact that gelatin can easily form a high-quality insulating film having a uniform film thickness by sol-gel transition and the property that solvent resistance can be easily imparted by a known hardener, It is used as a material for forming the gate insulating layer of the organic thin film transistor of the invention.

  In various studies regarding providing a uniform film thickness to a gate insulating layer (also referred to as a gate insulating film) of an organic thin film transistor, the present inventors paid attention to gelatin having a sol-gel transition property.

  Gelatin can easily undergo sol-gel transition depending on the temperature, and a gelatin solution coated by heating and dissolving is easily gelled only by cooling, and the shape is fixed even if the solvent is not completely volatilized.

  In addition, since the volatile components in the film are completely volatilized and dried after the gelatin solution is applied, the film thickness hardly changes due to disturbances such as mechanical vibration and air current, so a uniform film thickness is required. It is useful as a material for forming a gate insulating layer of an organic thin film transistor.

  Furthermore, when the gate insulating layer is formed using gelatin, gelatin molecules can be cross-linked without using a step such as ultraviolet irradiation or high-temperature heat treatment by using a conventionally known cross-linking agent such as a hardener. In addition, a gate insulating layer having excellent solvent resistance can be formed.

"gelatin"
The gelatin according to the present invention is generally produced from cow bone, cow skin, pork skin, etc. as raw materials, and in the production process from collagen, alkali-treated gelatin accompanied by treatment with lime or acid-treated gelatin accompanied by treatment with hydrochloric acid or the like. Yes, any gelatin may be applied as a component of the coating solution.

  For details on the production method and properties of these gelatins, see, for example, Arthur Veis, “The Macromolecular Chemistry of Gelatin”, pp. 187 to 217, (1964), (Academic Press), T. et al. H. James, “The Theory of the Photographic Process”, 4th. ed. 55, (1977), (Macmillan), “Niwa and Gelatin”, published by Nippon Gelatin Industries Association, (1987), “Basics of Photographic Engineering, Silver Salt Photography”, pages 119-124, (Corona) It is described in.

  Gelatin preferably has a jelly strength (by PAGI method) of 250 g or more. Gelatin preferably has a calcium content (according to the PAGI method) of 4000 ppm or less, and particularly preferably 3000 ppm or less.

  Examples of gelatin include alkali-treated gelatin having a molecular weight of about 100,000, acid-treated gelatin, oxidized gelatin, Bull. Soc. Sci. Photo. Japan. No. 16. Enzyme-treated gelatin as described in P30 (1966) can be preferably used, and chemically modified gelatin is also preferably used. Examples of the chemically modified gelatin include gelatin substituted with an amino group described in JP-A-5-72658, JP-A-9-197595, JP-A-9-251193, and the like. .

  The gelatin preferably has a methionine content of less than 30 μmol / g, more preferably less than 20 μmol / g, and even more preferably 0.1 μmol / g to 10 μmol / g.

  In order to reduce the methionine content in gelatin to less than 30 μmol / g, oxidation treatment of alkali-treated gelatin with an oxidizing agent is effective. Examples of the oxidizing agent that can be used for the oxidation treatment of gelatin include hydrogen peroxide, ozone, peroxy acid, halogen, thiosulfonic acid compounds, quinones, and organic peracids. Hydrogen peroxide is used. Is most preferred.

  There are many literatures on methods for measuring the methionine content of gelatin. For example, Journal of Photographic Science 28, 111, 40, 149, 41, 172, 42, 117, Journal of Imaging Science, 33, 10; Journal of・ Reference is made to Imaging Science and Technology vol.39, p.367.

  By referring to these documents, the methionine content of gelatin can be measured by amino acid analysis, HPLC (High Performance Liquid Chromatography), gas chromatography, silver ion titration, and the like.

  In order to calculate the mobility as the organic thin film transistor element, the dielectric constant of the insulating film is required. However, the dielectric constant of gelatin is in the range of 2.6 to 2.7, and will be described later, such as a hardening process. Even if it is performed, the range is almost the same.

<Gate insulating layer forming material that can be used in combination with gelatin>
In addition to gelatin, the gate insulating layer can be formed by laminating various compounds in a layered manner, or fine particles can be dispersed in the gelatin layer.

  Among these compounds, inorganic substances include 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, barium titanate, barium magnesium fluoride, bismuth titanate, strontium bismuth titanate, strontium bismuth tantalate, bismuth tantalate niobate, yttrium trioxide, and the like. Of these, preferred are silicon oxide, aluminum oxide, tantalum oxide, and titanium oxide. Inorganic nitrides such as silicon nitride and aluminum nitride can also be suitably used.

  Examples of organic substances include polyimides, polyamides, polyesters, polyacrylates, radical photopolymerization systems, photocationic polymerization system photocurable resins, or copolymers containing acrylonitrile components, polyvinylphenol, polyvinyl alcohol, novolac resins, and Cyanoethyl pullulan or the like can also be used.

<Method for forming gate insulating layer>
As a method for forming a gate insulating layer according to the present invention, a conventionally known coating method relating to coating of a gelatin solution can be applied. For example, a gelatin solution is applied to a substrate (substrate, support, etc.) using a wire bar or the like. It can be formed by coating on top.

  In wire bar coating, the film thickness of the coating film can be easily controlled by appropriately selecting the solution concentration and the wire thickness. The film thickness of the gate insulating layer according to the present invention is generally 50 nm to 3 μm, preferably 100 nm to 1 μm.

  As described above, since gelatin easily gels upon cooling, the solution containing gelatin is preferably applied by heating to 25 ° C. or higher. More preferably, it is 30 ° C. or higher. After coating, the gelatin thin film is gelled by cooling to 30 degrees or less, preferably 25 degrees or less in order to fix the shape, and the shape of the thin film can be easily fixed.

  Thereafter, after crosslinking and insolubilization by a hardening process described later, an insulating film made of gelatin can be obtained with a precise film thickness by performing heat drying.

  Further, as will be described in detail in the method for producing the organic thin film transistor, the present inventors have found that gelatin is useful as a constituent material of the gate insulating layer, and as a result, it is easy to form, expose and develop a photosensitive layer. It has been found that a gate insulating layer, a source electrode pattern, and a drain electrode pattern can be integrally formed by a process, and thus a method for manufacturing an organic thin film transistor with extremely high production efficiency can be provided.

《Hardener》
The hardener according to the present invention hardens the above gelatin and can adjust the swelling rate, film strength, etc. of the coating film depending on the amount thereof. It also has an effect of improving electrical characteristics such as a dielectric breakdown voltage of the gelatin layer.

  The gate insulating layer containing gelatin cross-linked with the hardener according to the present invention has a uniform film thickness, and improves the stabilization of the characteristics of the organic thin film transistor of the present invention and reduces the variation in the characteristics of each element. There is an effect of becoming.

  Examples of the hardener according to the present invention include aldehydes (formaldehyde, glyoxal, glutaraldehyde, etc.), mucohalogenoic acids (mucochloric acid, mucophenoxycyclolic acid, etc.), epoxy compounds, active halogen compounds (2,4-dichloro). -6-hydroxy-s-triazine, etc.), active vinyl derivatives (1,3,5-triacryloylhexahydro-s-triazine, bis (vinylsulfonyl) methyl ether, N, N'-methylenebis (β-vinylsulfonyl ( Propionamide)) etc.) Organic hardeners such as ethyleneimines, carbodiimides, methanesulfonates, isoxazoles, inorganic hardeners such as chromium alum, US Pat. No. 3,057,723 No. 3,396,029, No. 4,161,407 It includes polymeric hardeners such as described. Among these, it is preferable to use highly reactive vinyl sulfone hardeners and acrylamide hardeners.

  The hardener according to the present invention may be used alone or in combination of two or more.

<Surface treatment agent>
The gate insulating layer according to the present invention is preferably treated with a surface treatment agent.

  By performing surface treatment on the gate insulating layer, the surface energy on the surface of the gate insulating layer can be reduced, and as a result, the carrier trap density generated at the interface between the gate insulating layer and the organic semiconductor layer is reduced, and the carrier Mobility can be increased.

  In addition, when the surface energy after the surface treatment is expressed by a contact angle with respect to pure water, 50 degrees or more is preferable, 70 degrees to 170 degrees is more preferable, and 90 degrees to 130 degrees is more preferable.

  By having the above contact angle range, the carrier mobility and the on / off ratio of the organic thin film transistor element can be remarkably improved, and variations in characteristics between elements can be reduced. The contact angle can be measured using various contact angle meters (for example, dynamic contact angle meter DCA-VZ manufactured by Kyowa Interface Science Co., Ltd.).

  The surface treatment agent according to the present invention is preferably a compound capable of forming a chemical bond with gelatin, which is a main component constituting the insulating layer. The gelatin surface has an amino group and a carboxylic acid group as active functional groups, but a surface treating agent that reacts with the amino group is preferable because good semiconductor element characteristics can be obtained.

  As the surface treatment agent having such an effect, a compound represented by the general formula (1) is preferable, and a compound represented by the general formula (1) and a conventionally known surface treatment agent may be used in combination.

General formula (1)
A-R ₁
In the formula, A is an aldehyde group, N-methylol group, epoxy group, alkylcarbonyloxycarbonyl group, arylcarbonyloxycarbonyl group, halogen-substituted carbonyl group, vinylsulfonyl group, acryloylamino group, methacryloylamino group, ethyleneimine-2- It represents a functional group that can react with an amino group to form a bond selected from an yl group, an alkyl carbodiimide group, an aryl carbodiimide group, an isoxazolyl group, an alkoxysilyl group, and a halogenated silyl group.

  By having these substituents, a strong bond can be formed between the surface treatment agent and the gelatin layer. Among these functional groups, an aldehyde group, an acryloylamino group, a methacryloylamino group, and a vinylsulfonyl group are preferable, and among them, a vinylsulfonyl group is preferably used.

R ₁ represents an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, a heteroaryl group or an alkylsilyl group.

In the general formula (1), examples of the alkyl group represented by R ₁ include a methyl group, an ethyl group, a propyl group, an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, and an isopentyl group. , Neopentyl group, tert-pentyl group, hexyl group, isohexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group and the like.

In the general formula (1), examples of the cycloalkyl group represented by R ₁ include a cyclopentyl group and a cyclohexyl group.

In the general formula (1), examples of the alkenyl group represented by R ₁ include a vinyl group, allyl group, 1-propenyl group, 2-butenyl group, 1,3-butadienyl group, 2-pentenyl group, and isopropenyl. Groups and the like.

In the general formula (1), examples of the alkynyl group represented by R ₁ include an ethynyl group and a propargyl group.

In the general formula (1), the aryl group represented by R ₁ represented by R ₁ (also referred to as aromatic hydrocarbon group), for example, a phenyl group, p- chlorophenyl group, a mesityl group, a tolyl group, a xylyl Group, naphthyl group, anthryl group, azulenyl group, acenaphthenyl group, fluorenyl group, phenanthryl group, indenyl group, pyrenyl group, biphenylyl group and the like.

In the general formula (1), as the heteroaryl group represented by R ₁ represented by R ₁ (also referred to as a aromatic heterocyclic group), for example, a furyl group, a thienyl group, a pyridyl group, pyridazinyl group, pyrimidinyl group , Pyrazinyl group, triazinyl group, imidazolyl group, pyrazolyl group, thiazolyl group, quinazolinyl group, carbazolyl group, carbolinyl group, diazacarbazolyl group (one of the carbon atoms constituting the carboline ring of the carbolinyl group is a nitrogen atom) And a phthalazinyl group.

In the general formula (1), examples of the alkylsilyl group represented by R ₁ represented by R _1, for example, trimethylsilyl group, triisopropylsilyl group, tri-cyclohexyl silyl group, a triphenylsilyl group, a phenyl diethyl silyl group, A trimethoxysilyl group, a triethoxysilyl group, a silatrane group, etc. are mentioned.

In the general formula (1), each of the alkyl group, cycloalkyl group, alkenyl group, alkynyl group, aryl group, heteroaryl group, and alkylsilyl group represented by R ₁ may be unsubstituted or substituted. Furthermore, you may have.

  By having such a hydrophobic substituent, the surface treatment agent can adjust the surface energy within the aforementioned range.

  In the present invention, the hydrophobic substituent is defined as a substituent having LogP, which is a parameter representing hydrophobicity / hydrophilicity, of 0 or more, and preferably LogP is in the range of 2 to 10.

  LogP can be obtained from the partition coefficient of substances in two solvent systems, usually n-octanol and water. These are described in detail in Chemistry Special Issue 122 “Structure-Activity Relationship of Drugs” (Nanedo) pages 73-103. Are listed.

  In recent years, a method for calculating logP by calculation has been proposed. As a particularly useful method, software “CHEMLAB-II Revision 10.02” of Molecular Design Limited (USA) can be mentioned. As the logP in the present invention, a value calculated using this software “CHEMLAB-II Revision 10.02” is used.

  Among the compounds represented by the general formula (1), the compound represented by the general paper formula (2) is particularly preferably used.

  In the general formula (2), L represents an alkylene group, a cycloalkylene group, an alkenylene group, an alkynylene group or an arylene group. Examples of the alkylene group include an ethylene group, trimethylene group, tetramethylene group, propylene group, ethylethylene group, pentamethylene group, and hexamethylene group.

  In the general formula (2), examples of the cycloalkylene group represented by L include a cyclohexane-1,6-diyl group.

  Examples of alkenylene groups include vinylene, propenylene, butenylene, pentenylene, 1-methylvinylene, 1-methylpropenylene, 2-methylpropenylene, 1-methylpentenylene, 3-methyl. Examples include a pentenylene group, a 1-ethylvinylene group, a 1-ethylpropenylene group, a 1-ethylbutenylene group, and a 3-ethylbutenylene group.

  Examples of the alkynylene group include ethynylene group, 1-propynylene group, 1-butynylene group, 1-pentynylene group, 1-hexynylene group, 2-butynylene group, 2-pentynylene group, 1-methylethynylene group, 3-methyl-1 -Propinylene group, 3-methyl-1-butynylene group, etc. are mentioned.

  Examples of the arylene group include an o-phenylene group, m-phenylene group, p-phenylene group, naphthalenediyl group, anthracenediyl group, naphthacenediyl group, pyrenediyl group, naphthylnaphthalenediyl group, and biphenyldiyl group (for example, 3, 3 ′ -Biphenyldiyl group, 3,6-biphenyldiyl group, etc.), terphenyldiyl group, quaterphenyldiyl group, kinkphenyldiyl group, sexiphenyldiyl group, septiphenyldiyl group, octiphenyldiyl group, Biphenyldiyl group, deciphenyldiyl group, etc. are mentioned.

  These alkylene group, cycloalkylene group, alkenylene group, alkynylene group or arylene group may each be unsubstituted or may further have a substituent.

  In the general formula (2), Q represents C, Si, Ge, Sn, or Pb. Among them, Si is preferable.

In the general formula (2), in the formula, R _{2 to} R ₄ each represents an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, or an alkylsilyl group, and may be connected to each other to form a ring. .

  Hereinafter, although the specific example of a compound represented by General formula (1) or General formula (2) is shown, this invention is not limited to these.

  Each compound etc. which were mentioned as a specific example of the compound represented by the said General formula (1) or (2) are New J.J. Chem. 26 (2002), page 1515, Chem. Lett. 11 (1992), 2169, J. Am. Org. Chem. , 54 (1989), 1997, and J. Am. Org. Chem. 70 (2005), 4865, etc.

<< Method of forming gate electrode, source electrode and drain electrode patterns >>
In the organic thin film transistor of the present invention, the three electrode patterns of the source electrode pattern, the drain electrode pattern, and the gate electrode pattern can be used without limitation, regardless of any known electrode forming method.

  For example, vacuum deposition method, molecular beam epitaxial growth method, ion cluster beam method, low energy ion beam method, ion plating method, CVD method, sputtering method, and JP-A Nos. 11-43781 and 2003-179234, Dry process such as atmospheric pressure plasma method described in WO 04/75279 pamphlet, spray coating method, spin coating method, blade coating method, dip coating method, casting method, roll coating method, bar coating method, die coating Examples thereof include a method in which a conductive layer is formed on the entire surface by various known methods such as a wet process such as a method, and then an electrode is formed by using a known photolithographic method or a lift-off method.

  When it can be produced by a wet process, patterning may be performed directly by ink jetting, or a method of patterning conductive ink or paste by a printing method such as relief printing, intaglio printing, planographic printing, or screen printing may be used.

  The electrode material formed by these electrode forming methods 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 / antimony 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 / aluminum mixture , Metal compounds such as magnesium / indium mixture, lithium / aluminum mixture, and conductive metal oxides such as zinc oxide, tin oxide, indium tin oxide (ITO), fluorine-doped zinc oxide, conductive polyaniline, conductive polypyrrole, Examples thereof include conductive polythiophene, various conductive polymers whose conductivity is improved by doping such as a complex of polyethylene dioxythiophene and polystyrene sulfonic acid, and the like.

  However, preferably, a conductive pattern is formed by reducing a silver salt as described in, for example, US Pat. No. 2,600,333, Japanese Patent Publication No. 42-23746, and Japanese Patent Application Laid-Open No. 2004-221565. This is a method (hereinafter also referred to simply as a silver salt method). In these methods, since a binder made of gelatin is used to form an electrode pattern, an insulator layer made of gelatin and an electrode pattern layer can be integrally formed, and the manufacturing process is simplified. It is possible to provide a highly efficient method for manufacturing an organic thin film transistor.

  In addition, although the method of forming a conductive pattern from silver salt is well-known, the example applied to the gate electrode of a thin-film transistor, a source electrode, and a drain electrode is not seen.

  Hereinafter, an electrode forming method by the silver salt method will be described.

《Electrode pattern formation by silver salt method》
The electrode pattern formation method by the silver salt method is:
(1) A step of applying a photosensitive layer in which silver salt particles are dispersed in a binder resin,
(2) A step of exposing a portion desired to be a conductive pattern to the photosensitive layer,
(3) A developing step for removing an unexposed portion of the exposed photosensitive layer,
(4) a step of improving conductivity by plating the developed conductive pattern;
In this way, a conductive pattern having developed silver as a nucleus can be obtained.

  The silver salt method is not only capable of forming conductive patterns with very high accuracy to form from silver salt particles with excellent photosensitivity, but also suitable for roll-to-roll process and high processing speed, so the production speed It has the feature that it is excellent in, and is preferable.

《Silver salt particles》
Examples of the silver salt used as the silver salt particles used for forming the photosensitive layer of the source electrode pattern, the drain electrode pattern, and the gate electrode pattern according to the organic thin film transistor of the present invention include inorganic silver salts such as silver halide and silver acetate. Examples of the organic silver salt include silver halides having excellent characteristics as an optical sensor.

  As the silver halide used in the present invention, a silver halide emulsion technique used in a conventionally known silver salt photographic film, photographic paper, printing plate-making film, photomask emulsion mask or the like can be used as it is.

  The halogen element contained in the silver halide may be any of chlorine, bromine, iodine and fluorine, or a combination thereof. For example, silver halide mainly composed of AgCl, AgBr, and AgI is preferably used, and silver halide mainly composed of AgBr is preferably used.

  Here, “silver halide mainly composed of AgBr (silver bromide)” refers to silver halide in which the molar fraction of bromide ions in the silver halide composition is 50% or more. The silver halide grains mainly composed of AgBr may contain iodide ions and chloride ions in addition to bromide ions.

  Silver halide is in the form of solid grains, and from the viewpoint of image quality of the patterned metallic silver layer formed after exposure and development processing, the average grain size of silver halide is 0.1 nm to 1000 nm in terms of sphere equivalent diameter ( 1 μm), preferably 0.1 nm to 100 nm, more preferably 1 nm to 50 nm.

  Incidentally, the sphere equivalent diameter of silver halide grains is the diameter of grains having the same volume and a spherical shape.

  The shape of the silver halide grains is not particularly limited, and may be various shapes such as a spherical shape, a cubic shape, a flat plate shape (hexagonal flat plate shape, triangular flat plate shape, tetragonal flat plate shape, etc.), octahedron shape, and tetrahedron shape. Can be.

The silver halide used in the present invention may further contain other elements. For example, in a photographic emulsion, it is also useful to dope metal ions used to obtain a high-contrast emulsion. In particular, transition metal ions such as rhodium ions and iridium ions are preferably used because a difference between an exposed portion and an unexposed portion tends to occur clearly when a metallic silver image is generated. Transition metal ions represented by rhodium ions and iridium ions can also be compounds having various ligands. Examples of such a ligand include cyanide ions, halogen ions, thiocyanate ions, nitrosyl ions, water, hydroxide ions, and the like. Specific examples of the compound include K ₃ Rh ₂ Br ₉ and K ₂ IrCl ₆ .

In the present invention, the content of the rhodium compound and / or iridium compound contained in the silver halide is 10 ⁻¹⁰ mol / mol Ag to 10 ⁻² mol / mol Ag with respect to the number of moles of silver in the silver halide. It is preferably 10 ⁻⁹ mol / mol Ag, and more preferably 10 ⁻³ mol / mol Ag.

  In addition, in the present invention, silver halides containing Pd (II) ions or Pd metals can also be preferably used. Pd may be uniformly distributed in the silver halide grains, but is preferably contained in the vicinity of the surface layer of the silver halide grains.

  Here, Pd “contains in the vicinity of the surface layer of the silver halide grains” means that the Pd content is higher than the other layers within 50 nm in the depth direction from the surface of the silver halide grains. means. Such silver halide grains can be prepared by adding Pd in the course of forming silver halide grains. After adding silver ions and halogen ions to 50% or more of the total addition amount, Pd Is preferably added.

  It is also preferred that Pd (II) ions be present in the surface layer of the silver halide by a method such as addition at the time of post-ripening.

  The Pd-containing silver halide grains increase the speed of physical development and electroless plating, increase the production efficiency of a desired electrode pattern, and contribute to the reduction of production cost. Pd is well known and used as an electroless plating catalyst. However, in the present invention, Pd can be unevenly distributed on the surface layer of silver halide grains, so that extremely expensive Pd can be saved. is there.

In the present invention, the content of Pd ions and / or Pd metals contained in silver halide is 10 ⁻⁸ mol / mol Ag to 10 ⁻⁴ mol / mol Ag with respect to the number of moles of silver in the silver halide. It is preferably 10 ⁻⁶ mol / mol Ag, more preferably 10 ⁻⁵ mol / mol Ag.

Further, in order to suppress the binding with gelatin and coordinate more efficiently to AgX, it is preferably added as a Pd (SCN) ₂ complex or palladium glycinate.

Examples of the Pd compound used include PdCl ₄ and Na ₂ PdCl ₄ .

  In the present invention, chemical sensitization performed on a photographic emulsion can also be performed. As chemical sensitization, for example, noble metal sensitization such as gold sensitization, chalcogen sensitization such as sulfur sensitization, reduction sensitization or the like can be used.

  In the present invention, when a plurality of gate electrode patterns, source electrode patterns, and drain electrode patterns are formed by the silver salt method, conductive patterns corresponding to the respective electrode patterns may be sequentially formed. When spectral sensitization is applied to silver salt particles, two or more layers can be exposed and developed simultaneously, and thus spectral sensitization may be applied. For example, if the gate electrode pattern layer is spectrally sensitized so that it is exposed to red light, and the source electrode pattern layer and the drain electrode pattern layer are spectrally sensitized so as to be sensitive to blue light, the red light and the blue light are simultaneously 2 Since the pattern of the layer can be exposed, the electrode pattern can be formed more easily.

  The spectral sensitization of photographic emulsions can be performed by, for example, Research Disclosure (RD) No. 17643 (December 1978) p. 23 IV, ibid. 18716 (November 1979), pages 648-649 and ibid. 308119 (December 1989) 996-8 pages IIIA etc. can be used.

  Examples of emulsions that can be used in the present invention include color negatives described in Examples of JP-A-11-305396, JP-A-2000-321698, JP-A-13-281815, and JP-A-2002-72429. A film emulsion, a color reversal film emulsion described in JP-A No. 2002-214731, a color photographic paper emulsion described in JP-A No. 2002-107865, and the like can be suitably used.

"binder"
In the photosensitive layer (silver salt-containing layer) in which silver salt particles are dispersed in a binder resin, the binder (resin) uniformly disperses the silver salt particles and provides adhesion between the silver salt-containing layer and the support. It can be used for the purpose of assisting. In the present invention, both a water-insoluble polymer and a water-soluble polymer can be used as a binder, but a water-soluble polymer is preferably used.

  Examples of the water-soluble binder include gelatin, polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), starch and other polysaccharides, cellulose and derivatives thereof, polyethylene oxide, polyvinylamine, chitosan, polylysine, polyacrylic acid, polyalginic acid. , Polyhyaluronic acid, carboxycellulose and the like. These have neutral, anionic, and cationic properties depending on the ionicity of the functional group.

  Since silver halide gelatin emulsions for photography are used as silver halide grains, gelatin is most preferred in the binder resin.

  The gelatin used for the binder is preferably the same as the gelatin used for the gate insulating layer. As a result, the gate insulating layer is also formed at the same time when the source / drain electrode pattern and the gate electrode pattern are formed, and the process is greatly simplified.

  Content of the binder contained in a photosensitive layer (silver salt content layer) is not specifically limited, It can determine suitably in the range which can exhibit a dispersibility and adhesiveness. The content of the binder in the silver salt-containing layer is preferably 1/4 to 100 in terms of Ag / binder volume ratio, more preferably 1/3 to 10, and more preferably 1/2 to 2. Further preferred. Most preferably, it is 1 / 1-2.

  Moreover, if the binder is contained in the photosensitive layer (silver salt-containing layer) by 1/4 or more in terms of Ag / binder volume ratio, the metal particles are easily brought into contact with each other in the physical development and / or plating process, and have high conductivity. Since it can be obtained, it is preferable.

<Formation of photosensitive layer>
The photosensitive layer (silver salt-containing layer) is formed by applying a solution obtained by emulsifying and dispersing the silver salt with a binder.

  The solvent used in the formation of the solution containing the silver salt and the binder is not particularly limited. For example, water, organic solvents (for example, alcohols such as methanol, ketones such as acetone, amides such as formamide, dimethyl sulfoxide, etc. Sulphoxides, esters such as ethyl acetate, ethers, etc.), ionic liquids, and mixed solvents thereof. Since a photographic silver halide gelatin emulsion is used, a solvent mainly containing water is preferred.

  As a method for forming the photosensitive layer, known methods in the silver salt photography method are common coating methods such as a dip coating method, a slide coating method, a bar coating method, and the same method as the coating of the gate insulating layer made of gelatin. Can be applied on the substrate.

<< Exposure processing process >>
Next, the silver salt-containing layer is exposed to a portion where a conductive pattern is to be formed.

  As the light source, electromagnetic waves can be used. Examples of the electromagnetic wave include light such as visible light and ultraviolet light, and radiation such as X-rays. Furthermore, a light source having a wavelength distribution may be used for exposure, or a light source having a specific wavelength may be used.

  The pattern exposure method may be performed by scanning exposure using a laser beam, or may be performed by surface exposure using a photomask. The surface exposure method may be a refractive exposure using a lens or a reflection exposure using a reflecting mirror, and an exposure method such as contact exposure, proximity exposure, reduced projection exposure, or reflection projection exposure can be used.

  Among these, it is preferable to expose by scanning exposure using a cathode ray (CRT). The cathode ray tube exposure apparatus is simpler and more compact and less expensive than an apparatus using a laser. Also, the adjustment of the optical axis and color is easy. As the cathode ray tube used for image exposure, various light emitters that emit light in the spectral region are used as necessary.

  For example, one or more of a red light emitter, a green light emitter, a blue light emitter, and a near-infrared light emitter are used in combination.

  The spectral region is not limited to the above-mentioned near infrared, red, green, and blue, and phosphors that emit light in the yellow, orange, purple, or infrared region are also used. In particular, a cathode ray tube that emits white light by mixing these light emitters is often used. An ultraviolet lamp is also preferable, and g-line of a mercury lamp, i-line of a mercury lamp, etc. are also used.

  Further, the exposure in the present invention is a monochromatic high light source such as a gas laser, a light emitting diode, a semiconductor laser, a semiconductor laser, or a second harmonic light source (SHG) using a combination of a solid-state laser using a semiconductor laser as an excitation light source and a nonlinear optical crystal. A scanning exposure method using density light can be preferably used, and a KrF excimer laser, an ArF excimer laser, an F2 laser, or the like can also be used.

  In order to make the system compact and inexpensive, exposure is preferably performed using a semiconductor laser, a semiconductor laser, or a second harmonic generation light source (SHG) that combines a solid-state laser and a nonlinear optical crystal. In order to design an apparatus that is particularly compact, inexpensive, long-life, and high in stability, exposure is preferably performed using a semiconductor laser.

Specifically, as a laser light source, a blue semiconductor laser having a wavelength of 430 nm to 460 nm (announced by Nichia Chemical at the 48th Applied Physics Related Conference in March 2001) and a semiconductor laser (oscillation wavelength of about 1060 nm) are used. About 530 nm green laser, wavelength about 685 nm red semiconductor laser (Hitachi type No. HL6738MG), wavelength about 650 nm red semiconductor laser (wavelength converted by LiNbO ₃ SHG crystal with waveguide inversion domain structure) Hitachi type No. HL6501MG) is preferably used.

<Development process>
In the present invention, after the photosensitive layer (silver salt-containing layer) is exposed, development processing is further performed. The development processing can be performed by a normal development processing technique used for silver salt photographic film, photographic paper, printing plate-making film, photomask emulsion mask, and the like. The developer is not particularly limited, but a PQ developer, MQ developer, MAA developer, etc. can also be used. For example, CN-16, CR-56, CP45X, FD-3, Papitol manufactured by Fuji Film Co., Ltd. A developer such as C-41, E-6, RA-4, D-19, D-72 manufactured by KODAK, or a developer included in the kit, or a lith developer such as D-85 is used. be able to.

  In the present invention, a patterned metal silver portion is formed by performing the exposure and development processes described above.

  The development process can include a fixing process performed for the purpose of removing and stabilizing the silver salt in the unexposed part. The fixing process refers to a process performed for the purpose of removing and stabilizing unexposed silver halide grains after completion of development of exposed silver halide grains. For the fixing treatment in the present invention, a fixer formulation used for photographic films, photographic papers and the like using silver halide grains can be used. The fixing solution used in the fixing process may use sodium thiosulfate, potassium thiosulfate, ammonium thiosulfate, or the like as a fixing agent. Aluminum sulfate, chromium sulfate, or the like can be used as a hardener for fixing. As a preservative for the fixing agent, sodium sulfite, potassium sulfite, ascorbic acid, erythorbic acid and the like can be used, and citric acid, succinic acid and the like can be used. For the fixing process in the present invention, a known fixing process technique used for silver salt photographic film, photographic paper, film for printing plate making, emulsion mask for photomask, and the like can be used.

  The developer used in the development process can contain an image quality improver for the purpose of improving the image quality. Examples of the image quality improver include nitrogen-containing heterocyclic compounds such as benzotriazole. In addition, it is also preferable to use polyethylene glycol, particularly when a lith developer is used.

  In order to obtain high conductivity, the mass of the metallic silver contained in the exposed area after the development process should be 50% by mass or more based on the mass of silver contained in the exposed area before the exposure. Is preferable, and it is more preferable that it is 80 mass% or more.

  The gradation after development processing in the present invention is not particularly limited, but is preferably more than 4.0. When the gradation after the development processing exceeds 4.0, the conductivity of the conductive metal portion can be increased while keeping the transparency of the light transmissive portion high. Examples of means for setting the gradation to 4.0 or higher include the aforementioned doping of rhodium ions and iridium ions.

<< Plating process >>
The plating process according to the present invention will be described.

  When manufacturing a display using organic thin-film transistors, the source electrode pattern, drain electrode pattern, gate electrode pattern, and the wiring that connects them do not transmit light, so if these electrode patterns are wide, the aperture ratio of the display decreases. However, a high-quality display cannot be obtained. Therefore, it is necessary to make these electrode patterns as thin as possible. However, if the width of the electrode pattern is reduced, the conductivity is lowered, and it becomes difficult to flow a uniform voltage / current to the transistors of each pixel. Therefore, these electrode pattern portions need to have high conductivity.

  Although conductive metal silver patterns have been formed by the exposure process described above, these metal silver patterns are aggregates of fine particles and therefore have insufficient conductivity. The organic thin film transistor array having a uniform characteristic and a high-quality display can be obtained.

  As the plating treatment, electroless plating (chemical reduction plating or displacement plating), electrolytic plating, or both electroless plating and electrolytic plating can be used. However, in the present invention, electroless plating treatment (simply electroless plating and May be preferred).

  For the electroless plating in the present invention, a known electroless plating technique can be used, for example, an electroless plating technique used in a printed wiring board or the like can be used, and the electroless plating is an electroless copper plating, Electroless silver plating and electroless gold plating are preferred.

  In the silver salt photography field, a process called “physical development” can be regarded as an electroless silver plating process.

  The conductive metal pattern formed by these treatments is not limited as long as it is a metal that can be formed on silver. Platinum, gold, silver, copper, iron, tin, zinc, aluminum, indium, nickel A metal such as chromium can be used, but a metal selected from platinum, gold, silver, copper, aluminum, and indium is preferably used.

  For example, when performing electroless copper plating, copper sulfate or copper chloride, formalin or glyoxylic acid as a reducing agent, EDTA or triethanolamine as a copper ligand, etc., bath stabilization or smooth plating film The metallic silver pattern portion is treated with a solution containing polyethylene glycol, yellow blood salt, bipyridine and the like as additives for improving the properties. Other electrolytic copper plating baths include a copper sulfate bath and a copper pyrophosphate bath.

  The plating speed during the plating process can be performed under moderate conditions, and high-speed plating of 5 μm / hour or more is also possible. In the plating treatment, various additives such as a ligand such as EDTA can be used from the viewpoint of improving the stability of the plating solution.

  Even when a metal other than copper is used, the electroless plating process can be performed by changing the metal ion species and performing the same process.

  Regarding the method of forming an electrode by an electroless plating method, as described in JP-A-2004-158805 (Asahi Kasei), a liquid containing a plating catalyst that causes electroless plating by acting with a plating agent on a portion where an electrode is provided Specifically, for example, after patterning by a printing method (including inkjet printing), a plating agent is brought into contact with a portion where an electrode is provided. If it does so, electroless plating will be performed to the said part by the contact of the said catalyst and a plating agent, and an electrode pattern will be formed.

  The application of the electroless plating catalyst and the plating agent may be reversed, and the pattern formation may be performed either. However, a method of forming a plating catalyst pattern and applying the plating agent to this is preferable.

  As the electroless silver plating process, it is preferable to use a process called “physical development” in the silver salt photography industry. “Physical development (also called physical development processing)” means that silver ions such as silver ions from other than inside the silver halide grains having a latent image by exposure are reduced with a reducing agent to deposit metal particles, thereby reinforcing developed silver. Indicates the process to perform. This physical phenomenon is used for instant B & W film, instant slide film, printing plate manufacturing, and the like, and the technology can be used in the present invention. The physical development may be performed simultaneously with the development processing after exposure or separately after the development processing, but it is preferable to perform the physical development processing before performing the fixing processing described later.

  As a specific method for supplying silver ions from the developing solution, for example, a method of dissolving silver nitrate or the like in advance in a developing solution and dissolving silver ions, or sodium thiosulfate in the developing solution, Examples include a method in which a silver halide solvent such as ammonium thiocyanate is dissolved, unexposed silver halide is dissolved during development, and development of silver halide grains having a latent image is supplemented.

  In addition, when electroplating is performed after electroless plating is performed, it is possible to obtain a display having higher conductivity, an electrode pattern having fine wiring, and a high aperture ratio.

  As the electroplating method in the present invention, a conventionally known method can be used. In addition, as a metal used for the electroplating of this process, it is preferable to use a metal with good electrical junction with an organic semiconductor material, and it is preferable to use a metal selected from platinum, gold, silver, and copper. Among them, it is preferable to perform electroplating using gold.

  The film thickness of the electrode pattern obtained by electroplating can be controlled by adjusting the concentration of metal contained in the plating bath, the immersion time, or the current density.

<Oxidation treatment>
In the present invention, oxidation treatment is preferably performed on the metallic silver portion after the development treatment and the conductive metal portion (also referred to as a conductive pattern) formed after the physical development treatment or the plating treatment step. The oxidation treatment is a treatment for removing metal adhering to a portion other than a desired pattern portion, and can prevent deterioration of characteristics of the organic thin film transistor of the present invention.

  Examples of the oxidation treatment include known methods using various oxidizing agents such as Fe (III) ion treatment. The oxidation treatment can be performed after exposure and development processing of the silver salt-containing layer, or after physical development or plating treatment, and may be performed after development processing and after physical development or plating treatment.

  In the present invention, the metallic silver portion after the exposure and development treatment can be further treated with a solution containing Pd. Pd may be a divalent palladium ion or metallic palladium. This treatment can accelerate electroless plating or physical development speed.

《Binder layer post-treatment》
The electrode pattern thus formed is formed on the binder resin layer. When forming other layers such as a gate insulating layer and an organic semiconductor layer on the electrode pattern, the binder layer dissolves, decomposes, and deforms to avoid adversely affecting the performance of the thin film transistor. After the formation is completed, it is preferable to perform a post-treatment such as removing the binder layer or insolubilizing with a crosslinking reaction or the like.

  When the binder layer is used as a gate insulating layer as it is, a crosslinking treatment is performed. When the binder layer is cross-linked, dissolution / deformation and the like can be prevented by using the above various hardeners.

  Moreover, as a method of removing a binder layer, it can wash | clean with the solvent which a binder melt | dissolves, or can remove by methods, such as dry etching using the etching rate difference with an electrode pattern part.

《Electrode surface treatment》
The surface of the electrode pattern formed by various methods may be subjected to any surface treatment for the purpose of modifying the surface energy and various characteristics. For example, octadecyltrichlorosilane, trichloromethylsilazane, and silane coupling agents such as compounds described in Japanese Patent Application No. 2006-82419, alkane phosphoric acid, alkanesulfonic acid, alkanecarboxylic acid, and the like, and alkylthiol and arylthiol. A self-assembled alignment film or the like is preferably used.

《Organic semiconductor material》
An organic semiconductor material used for forming an organic thin film transistor will be described.

  Since the conductivity of an organic semiconductor material needs to change according to the electric field applied to the gate electrode, mobility and the ON / OFF ratio are important as indicators of the performance of the organic semiconductor material.

Although mobility and ON / OFF ratio is varied as required according to the purpose, for example, in applications such as electronic paper, the carrier mobility of 0.01cm ² /Vsec~1.0cm ² / Vsec The ON / OFF ratio is preferably in the range of 1.0 × 10 ^{5 to} 1.0 × 10 ⁷ . By setting it as such a range, a display can be driven at sufficient speed and a favorable gradation can be provided to a display.

  As long as the organic semiconductor material satisfies such requirements, various condensed polycyclic aromatic compounds and conjugated compounds are applicable.

  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, Chem. Commun. 1998, 1661, JP-A-2003-304104 and the like, and porphyrins and metal compounds thereof, naphthalene 1,4,5,8-tetracarboxylic acid diimide, N, N′-bis (4-trifluoromethylbenzyl) ) 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-tetracarboxylic acid Condensed ring tetracarboxylic acid diimides such as anthracene tetracarboxylic acid diimides such as acid diimide Organic molecular complexes such as C, Fullerenes such as 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 2000-260999 A Organic / inorganic hybrid materials can also be used.

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

  Although the compound example preferably used for the organic thin-film transistor array of this invention below is shown, this invention is not limited to these.

  In order to form the semiconductor layer of the organic thin film transistor, the organic semiconductor material according to the present invention can be formed by a known method, for example, vacuum deposition, MBE (Molecular Beam Epitaxy), ion cluster beam method, low energy ion beam. Method, ion plating method, sputtering method, CVD (Chemical Vapor Deposition), laser deposition, electron beam deposition, electrodeposition, spin coating, dip coating, bar coating method, die coating method, spray coating method, LB method, etc. Examples include screen printing, ink jet printing, blade coating, and the like.

  However, from the viewpoint of productivity, it is preferable that a solution prepared by dissolving in an appropriate solvent and adding an additive as necessary is placed on the substrate by cast coating, spin coating, printing, an inkjet method, an ablation method, or the like.

  In this case, the solvent for dissolving the organic semiconductor material according to the present invention is not particularly limited as long as the organic semiconductor material can be dissolved to prepare a solution having an appropriate concentration. Specifically, diethyl ether or diisopropyl is used. Chain ether solvents such as ether, cyclic ether solvents such as tetrahydrofuran and dioxane, ketone solvents such as acetone and methyl ethyl ketone, alkyl halide solvents such as chloroform and 1,2-dichloroethane, toluene, o-dichlorobenzene, Aromatic solvents such as nitrobenzene and m-cresol, N-methylpyrrolidone, carbon disulfide and the like can be mentioned.

  Of these solvents, a solvent containing a non-halogen solvent is preferable, and a non-halogen solvent is preferable. In addition, when the insulating film surface is applied on an insulating film hydrophobized, it is preferably a nonpolar solvent having a surface energy smaller than the surface energy of such a hydrophobic surface, such as hexane, cyclohexane, toluene. Etc. are preferred.

  In the organic thin film transistor of the present invention, an organic semiconductor material described later is preferably used for the semiconductor layer. The semiconductor layer is preferably formed by applying a solution or dispersion containing these organic semiconductor materials. In addition, when carbon nanotubes are used as a semiconductor material, a method of dispersing and coating in a gelatin solution as described in JP-A-2006-27961 can be preferably used.

  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, it is preferably 1 μm or less, particularly preferably 10 nm to 300 nm.

<< Substrate (substrate, support, etc.) >>
The substrate (substrate, support, etc.) is made of glass or a flexible resin sheet. For example, a plastic film can be used as the sheet. Examples of the plastic film include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate (PC). And a film made of triacetyl cellulose (TAC), diacetyl cellulose (DAC), cellulose acetate propionate (CAP), or the like. Thus, 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.

  From the viewpoint of transparency, heat resistance, ease of handling and price, the plastic film is preferably a polyethylene terephthalate film (PET) or polyethylene naphthalate (PEN).

  Further, since transparency is required for display use, it is desirable that the support is highly transparent. The total visible light transmittance of the plastic film or plastic plate is preferably 70 to 100%, more preferably 90%. % To 100%.

<< Method for Manufacturing Display Backplane Composed of Organic Thin Film Transistor >>
A display backplane can be formed by arranging the organic thin film transistors having the above-described configuration vertically and horizontally as shown in FIG.

  FIG. 2 is a diagram showing an example of a schematic equivalent circuit diagram of an organic thin film transistor sheet.

  The organic thin film transistor sheet 10 has a large number of organic thin film transistors 11 arranged in a matrix. 7 is a gate bus line of each organic thin film transistor 11, and 8 is a source bus line of each organic thin film transistor 11. An output element 12 is connected to the source electrode of each organic thin film transistor 11, and this output 12 is, for example, a liquid crystal, an electrophoretic element or the like, and constitutes a pixel in the display device. The pixel electrode may be used as an input electrode of the photosensor. In the illustrated example, a liquid crystal as an output element is shown by an equivalent circuit composed of a resistor and a capacitor. 13 is a storage capacitor, 14 is a vertical drive circuit, and 15 is a horizontal drive circuit.

  Hereinafter, although the organic thin-film transistor array of an Example and a comparative example is produced, this invention is not limited to these.

  In both examples and comparative examples, the transistor array is a bottom gate / bottom contact type, W / L = 250 μm / 50 μm, and the gate insulating film thickness = 500 μm. It produced as follows.

  The structures of the compounds used in the examples are shown below.

Example 1
<< Preparation of Organic Thin Film Transistor Array 1 >>: Comparative Example A comparative organic thin film transistor array 1 was prepared with reference to Example 1 of Patent Document 4.

A biaxially stretched polyethylene terephthalate film (hereinafter referred to as PET film) substrate having a thickness of 100 μm was subjected to hydrophilic treatment by corona discharge at 12 W · min / m ² , and then the PET film was covered with a shadow mask having a width of 1.2 mm. A gate electrode was formed by vapor-depositing aluminum with a thickness of 1000 mm at a vacuum degree of 0.13 mPa using a vacuum vapor deposition machine ("EX-400" manufactured by ULVAC).

On this, a polyvinyl cinnamate solution (manufactured by Aldrich, weight average molecular weight 200,000) solution dissolved in chloroform at a concentration of 5% by mass and filtered through a 0.2 μm filter was applied with a wire bar and dried. Then, ultraviolet rays were irradiated at an irradiation amount of 300 mJ / cm ² to carry out a crosslinking reaction, thereby forming a gate insulating layer.

  When the surface roughness (Ra) of the obtained gate insulating film was measured using an atomic force microscope (AFM) SPA400 manufactured by Seiko Instruments Inc., the center line average roughness was 18 nm.

  The above surface roughness (Ra) is obtained using the definition and measurement method described in JIS B 0601-1994.

  Next, on this gate insulating layer, in order to form a source electrode and a drain electrode, it is covered with the shadow mask having the above-mentioned channel shape, chromium is deposited to a thickness of 5 nm, gold is deposited to a thickness of 50 nm, and Produced.

  Subsequently, the organic semiconductor material (1) was dissolved in toluene at 1.0% by mass, and a microinjector manufactured by Narishige Co., Ltd., at room temperature in a nitrogen atmosphere so as to completely cover the channel portion opposed to the source electrode and the drain electrode. Application was performed using IM300.

<Measurement of electrolysis mobility>
About each transistor element of the obtained organic thin-film transistor array, the voltage-current curve when using a semiconductor parameter analyzer (Agilent 4155) and sweeping the source-drain voltage from 50 V to -50 V to +30 V From this, the field effect mobility was calculated.

As a result of calculating the field effect mobility, the average mobility of the 10 elements was 0.036 cm ² / Vs, and the variation in mobility was within the range of ± 80% from the average value.

<< Preparation of Organic Thin-Film Transistor Array 2 >>: Present Invention The organic thin-film transistor array 2 was prepared in the same manner as the preparation of the organic thin-film transistor array 1 except that the configuration was as shown in Table 1.

<Formation of undercoat layer>
The following undercoat coating solution B-1 was applied on the PET film on which the gate electrode prepared above was formed to a dry film thickness of 0.4 μm.

<< Undercoat coating liquid B-1 >>
Copolymer latex liquid (solid content 30%) of butyl acrylate 30% by mass, t-butyl acrylate 20% by mass, styrene 25% by mass, 2-hydroxyethyl acrylate 25% by mass 50 g
Compound (UL-1) 0.2g
Hexamethylene-1,6-bis (ethyleneurea) 0.05g
Finish with water 1000ml
<< Formation of source electrode pattern and drain electrode pattern >>
The electrode-forming emulsion M2 prepared as follows was coated on the undercoated PET film support with a wire bar under light shielding so that the amount of gelatin applied was 1.0 g / m ² and dried. It was.

<< Preparation of Emulsion M-1 for Forming Gate Electrode >>
The following (M1A solution) and (M1B solution) were simultaneously added to 1 liter of a 0.5% gelatin aqueous solution kept at 35 ° C. while controlling the silver potential (EAg) = 85 mV and pH = 5.8, and (M1C solution) and (M1D solution) were simultaneously added while controlling EAg = 85 mV and pH = 5.8. At this time, the silver potential was controlled using a 10% potassium bromide aqueous solution, and the pH was controlled using acetic acid or a sodium hydroxide aqueous solution.

(M1A solution)
Potassium bromide 104g
Potassium iodide 3.0g
1300ml with water
(M1B solution)
150 g silver nitrate
1360ml with water
(M1C solution)
310g of potassium bromide
Potassium hexachloroiridium (IV) 4 × 10 ⁻⁸ mol Potassium hexacyanoferrate (II) 2 × 10 ⁻⁵ mol Potassium iodide 10 g
4000ml with water
(M1D solution)
480 g of silver nitrate
4200ml with water
After the addition, desalting was performed using a 5% aqueous solution of Demol N manufactured by Kao Atlas and a 20% aqueous solution of magnesium sulfate, and then mixed with an aqueous gelatin solution to obtain an average particle size of 0.04 μm and a coefficient of variation in particle size distribution. A 0.13 silver halide emulsion was obtained.

  The silver halide emulsion was chemically sensitized with 2.0 mg of sodium thiosulfate per mole of silver halide at 40 ° C. for 80 minutes, and after completion of chemical sensitization, 4-hydroxy-6-methyl-1,3 , 3a, 7-tetrazaindene (TAI) was added in an amount of 500 mg per mole of silver halide to obtain a silver halide emulsion M1E.

  Using this silver halide emulsion M1E, additional gelatin was adjusted so that the volume ratio of silver halide grains to gelatin (silver halide grains / gelatin) was 1.4, and a hardener (H-1 : Tetrakis (vinylsulfonylmethyl) methane) was added at a ratio of 30 mg / g of gelatin to prepare an emulsion M-1 for electrode formation.

(Formation of gate insulating layer, source electrode pattern, and drain electrode pattern)
Using a CTP setter (manufactured by ECRM) with a laser wavelength of 405 nm, a PET film coated with the electrode forming emulsion M-2 is 2400 dpi (where dpi is a dot per inch (2.54 cm)). The film was exposed through a mask having the electrode pattern under the conditions (representing the number).

  Thereafter, development processing at 25 ° C. for 60 seconds using the following developer (D-1), followed by physical development processing (electroless silver plating) at 45 ° C. for 60 seconds using the following physical developer (P-1) Next, after performing a fixing treatment at 25 ° C. for 120 seconds using a fixing solution (F-1), washing with warm pure water at 40 ° C. for 5 minutes, and then drying with warm air at 40 ° C. for 30 minutes. Furthermore, a crosslinking treatment was performed using a crosslinking agent (C-1). After the completion of the crosslinking treatment, the following electroless gold plating solution P-1 was further treated at 45 ° C. for 3 minutes, and washed sequentially with 60 ° C. pure water and 30 ° C. isopropanol, whereby the outermost surface was formed of gold. A source electrode pattern and a drain electrode pattern were formed.

  After washing with warm pure water at 40 ° C. for 5 minutes, drying was performed with warm air at 40 ° C. for 30 minutes. As a result, a gate electrode pattern having a desired shape was obtained.

  As a result, a gate insulating layer made of hardened gelatin having a source electrode pattern and a drain electrode pattern having a desired shape was obtained. The center line surface roughness of this gate insulating layer was 2.4 nm.

(Developer D-1)
500 ml of pure water
Metol 2g
80 g of anhydrous sodium sulfite
Hydroquinone 4g
4g borax
Sodium thiosulfate 10g
Potassium bromide 0.5g
Add water to make 1 liter (physical developer P-1)
1 L aqueous solution containing 5 g hydroquinone and 10 g citric acid
1L aqueous solution containing 35g of silver nitrate
An aqueous solution within 30 minutes after mixing the above two aqueous solutions (fixing solution F-1)
750 ml of pure water
Sodium thiosulfate 250g
Anhydrous sodium sulfite 15g
Glacial acetic acid 15ml
Potash alum 15g
Add water to make the total volume 1 liter (Crosslinking agent C-1)
750 ml of pure water
Glutaraldehyde 15g
(Electroless gold plating solution P-1)
Potassium dicyano gold 0.1 mol Sodium oxalate 0.1 mol Potassium sodium tartrate 0.1 mol Add water to make 1 liter << Formation of organic semiconductor layer and evaluation of organic thin film transistor array >>
The organic semiconductor material (1) was dissolved in toluene at 0.1% by mass, and a microinjector IM300 manufactured by Narishige Co., Ltd. was used at room temperature in a nitrogen atmosphere so as to completely cover the channel portion where the source electrode and the drain electrode faced each other. And applied.

As a result of calculating the field effect mobility in the same manner for each transistor element of the obtained organic thin film transistor array, the average mobility of 10 elements was 0.034 cm ² / Vs, and the variation in mobility was from the above average value. An organic thin film transistor array having a good mobility within a range of ± 45% could be produced with low variations.

<< Preparation of Organic Thin Film Transistor Array 3 >>: Present Invention The organic thin film transistor 3 of the present invention was prepared as follows.

A hydrophilic treatment was performed on a PET film having a thickness of 100 μm by corona discharge of 12 W · min / m ² , and then the undercoat coating solution B1 was applied under the same conditions as those for the production of the organic thin film transistor array 2.

<< Formation of gate electrode pattern >>
Next, the electrode-forming emulsion M-1 was applied on the PET film on which the undercoat layer had been formed under the same conditions as in Example 1, dried, and then similarly using a CTP setter having a laser wavelength of 405 nm. It exposed through the mask which has the following gate electrode patterns below on 2400 dpi conditions.

  Thereafter, development processing at 25 ° C. for 60 seconds using the developer (D-1) was performed, and then physical development processing (electroless silver) at 45 ° C. for 60 seconds using the physical developer (P-1). Then, after performing a fixing treatment at 25 ° C. for 120 seconds using the fixing solution (F-1), a crosslinking treatment was further performed using the following crosslinking agent (C-1).

  After the crosslinking treatment, it was washed with warm pure water at 40 ° C. for 5 minutes, and then dried with warm air at 40 ° C. for 30 minutes. As a result, a gate electrode pattern having a desired shape was obtained.

<< Formation of gate insulating layer and electrode pattern >>
Next, the gate electrode except that the electrode forming emulsion M-1 was further coated on the PET film on which the gate electrode pattern was formed, and the pattern at the time of exposure using the CTP setter was changed to the source / drain electrode pattern. The same processing as that for forming the pattern was performed to form a source electrode pattern and a drain electrode pattern made of developed silver, and a gate insulating film made of gelatin.

  At this time, the center line average roughness was 1.2 nm.

(Surface treatment of gate insulating film)
The organic thin film transistor array substrate produced above was treated in a 10 mmol / L ethanol solution of Exemplified Compound 11 at 60 ° C. for 10 minutes, and then washed with pure water at 60 ° C. and then with isopropanol at 30 ° C.

<< Formation of organic semiconductor layer and evaluation of organic thin film transistor array >>
The organic semiconductor material (1) was dissolved in toluene at 0.1% by mass, and a microinjector IM300 manufactured by Narishige Co., Ltd. was used at room temperature in a nitrogen atmosphere so as to completely cover the channel portion where the source electrode and the drain electrode faced each other. And applied.

As a result of calculating the field effect mobility in the same manner for each transistor element of the obtained organic thin film transistor array, the average mobility of the 10 elements was 0.055 cm ² / Vs, and the variation in mobility was from the average value. An organic thin film transistor array having a good mobility within the range of ± 35% could be produced with low variations.

<< Preparation of Organic Thin-Film Transistor Array 4 >>: The organic thin-film transistor array in the same manner as in the step of the organic thin-film transistor array 2 except that the surface treatment agent for the gate insulating film is replaced with the exemplified compound 13 instead of the exemplified compound 11 4 was prepared and evaluated in the same manner.

The average mobility of 10 elements is 0.072 cm ² / Vs, and the variation in mobility is within ± 30% of the average value, and an organic thin film transistor array having good mobility is manufactured with low variation. I was able to.

<< Preparation of organic thin film transistor array 5 >>
In the process of the organic thin film transistor array 2, the organic thin film transistor array 5 was similarly produced and evaluated in the same manner except that the surface treatment agent for the gate insulating film was changed to the exemplified compound 34 instead of the exemplified compound example 11.

The average mobility of 10 elements is 0.089 cm ² / Vs, and the variation in mobility is within ± 30% of the average value, and an organic thin film transistor array having good mobility is manufactured with low variation. I was able to.

<< Production of Organic Thin Film Transistor Array 6 >>
An organic thin film transistor array 6 was prepared in the same manner except that the organic semiconductor material (1) was replaced with the organic semiconductor material (2) in the step of the organic thin film transistor array 4, and was similarly evaluated.

The average mobility of 10 elements is 0.18 cm ² / Vs, and the variation in mobility is within a range of ± 25% from the average value, and an organic thin film transistor array having good mobility is manufactured with low variations. I was able to.

  The obtained results are shown in Table 1 below.

  From Table 1, it can be seen that the organic thin film transistor of the present invention has high mobility and less variation than the comparison.

It is a figure which shows the structural example of the organic TFT which concerns on this invention. It is an example of the schematic equivalent circuit schematic of the organic TFT of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Organic-semiconductor layer 2 Source electrode 3 Drain electrode 4 Gate electrode 5 Insulating layer 6 Support body 7 Gate bus line 8 Source bus line 10 Organic thin-film transistor sheet 11 Organic thin-film transistor 12 Output element 13 Storage capacitor 14 Vertical drive circuit 15 Horizontal drive circuit

Claims (15)

In an organic thin film transistor having a semiconductor layer containing at least a gate electrode pattern, a gate insulating layer, a source electrode pattern, a drain electrode pattern, and an organic semiconductor material on a substrate,
An organic thin film transistor, wherein the gate insulating layer contains gelatin crosslinked by a hardener. 2. The organic thin film transistor according to claim 1, wherein the gate insulating layer is surface-treated using a compound represented by the following general formula (1).
General formula (1)
A-R ₁
[Wherein, A is an aldehyde group, N-methylol group, epoxy group, alkylcarbonyloxycarbonyl group, arylcarbonyloxycarbonyl group, halogen-substituted carbonyl group, vinylsulfonyl group, acryloylamino group, methacryloylamino group, ethyleneimine-2 - yl group, an alkyl carbodiimide group, an aryl carbodiimide group, isoxazolyl group, an alkoxysilyl group, a halogenated silyl group, a functional group capable of forming a bond by reacting with an amino group, R ₁ is an alkyl group, a cycloalkyl An alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heteroaryl group or an alkylsilyl group is represented. ] 3. The organic thin film transistor according to claim 1, wherein A is a vinylsulfonyl group. The organic thin film transistor according to any one of claims 1 to 3, wherein the gate insulating layer is surface-treated using a compound represented by the following general formula (2).

[In the formula, L represents an alkylene group, a cycloalkylene group, an alkenylene group, an alkynylene group or an arylene group, Q represents C, Si, Ge, Sn or Pb, and R _{2 to} R ₄ each represents an alkyl group, It represents a cycloalkyl group, an aryl group, a heteroaryl group or an alkylsilyl group, and may be linked to each other to form a ring. ] The organic thin film transistor according to claim 1, wherein Q represents Si. A bottom contact structure is formed in which a gate electrode pattern, a gate insulating layer, a source electrode pattern, a drain electrode pattern, and a semiconductor layer containing an organic semiconductor material are stacked in this order on the substrate. The organic thin film transistor according to any one of claims 1 to 5. The source electrode pattern and the drain electrode pattern are electrode patterns formed through an exposure process, a development process, and a plating process on a photosensitive layer in which silver salt particles are dispersed in a binder resin. The organic thin-film transistor according to any one of claims 1 to 6, characterized in that The organic thin film transistor according to claim 7, wherein the binder resin is gelatin. The organic thin film transistor according to claim 7 or 8, wherein the silver salt grains are silver halide grains. The organic thin film transistor according to any one of claims 7 to 9, wherein the metal formed by the plating process is gold. The organic thin film transistor according to any one of claims 1 to 10, wherein the organic semiconductor material is a pentacene derivative. In manufacturing the organic thin film transistor according to any one of claims 1 to 11,
(A) forming a photosensitive layer in which silver salt particles are dispersed in gelatin on a gate electrode pattern by coating;
(B) a step of obtaining a metallic silver pattern through an exposure step and a development treatment on the photosensitive layer;
(C) A step of forming a source electrode pattern and a drain electrode pattern through a plating process on the metal silver pattern,
A method for producing an organic thin film transistor, comprising: The method for producing an organic thin film transistor according to claim 12, further comprising a step of surface-treating the surface of the gate insulating layer with the compound represented by the general formula (1) or (2). The method of manufacturing an organic thin film transistor according to claim 12 or 13, wherein the plating process includes a gold plating process. The method for producing an organic thin film transistor according to any one of claims 12 to 14, further comprising a step of forming a semiconductor layer containing the organic semiconductor material by coating.

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