Thin film transistor element and manufacturing method thereof

Abstract

This thin film transistor element comprises a gate layer (31), an oxide semiconductor thin film (4), a gate insulating film (2) arranged between the gate layer and the oxide semiconductor thin film, a pair of source and drain electrodes (51, 52) in contact with the oxide semiconductor thin film, and a resin film (6) that covers the oxide semiconductor thin film. The oxide semiconductor thin film contains two or more metal elements selected from the group consisting of In, Ga, Zn, and Sn. After a composition containing an SiH-group-containing compound is applied to the oxide semiconductor thin film, the resin film is formed by heating. The heating temperature during resin film formation is preferably 190-450°C. The SiH-group-containing compound in the composition preferably contains 0.1 mmol / g or more of SiH groups. The resin film may also have SiH groups.

Description

[Technical Field]

[0001] The present invention relates to a thin film transistor element and a method for manufacturing the same. [Background technology]

[0002] Thin film transistors (TFTs) using oxide semiconductors such as InGaZnO have higher electron mobility and superior electrical properties than amorphous silicon TFTs, and are therefore expected to be used as driving elements for organic electroluminescence (EL) displays and as power-saving elements. As with conventional amorphous silicon thin film transistors, thin film transistors using oxide semiconductors often have an insulating protective film formed on the semiconductor thin film to protect the semiconductor thin film from the external atmosphere, in order to improve the operational stability of the device. For example, Patent Document 1 proposes applying a photosensitive composition containing a siloxane resin onto an oxide semiconductor thin film, patterning it by photolithography, and then heat-curing the composition to form a protective film. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-89971 Summary of the Invention [Problem to be solved by the invention]

[0004] TFT elements using oxide semiconductors have high electron mobility, but from the viewpoint of improving switching speed and power saving, there is a demand for the development of elements with even higher electron mobility. [Means for solving the problem]

[0005] One embodiment of the present invention is a thin-film transistor element comprising a gate layer, an oxide semiconductor thin film, a gate insulating film disposed between the gate layer and the oxide semiconductor thin film, a pair of source and drain electrodes in contact with the oxide semiconductor thin film, and a resin film covering the oxide semiconductor thin film. The thin-film transistor element may be a bottom-gate type in which a gate insulating film covering the gate layer is provided and an oxide semiconductor thin film is provided thereon, or a top-gate type in which a gate insulating film is provided on the oxide semiconductor thin film and a gate layer is provided thereon. The oxide semiconductor thin film contains two or more metal elements selected from the group consisting of In, Ga, Zn, and Sn. An example of the oxide is InGaZnO.

[0006] In the manufacture of a thin film transistor element, a composition containing a SiH group-containing compound is applied onto an oxide semiconductor thin film, and then heated to form a resin film in contact with the oxide semiconductor thin film. The heating temperature during resin film formation is preferably 190 to 450°C. The amount of SiH groups in the SiH group-containing compound is preferably 0.1 mmol / g or more. The SiH group-containing compound may be a polymer and may contain a polysiloxane structure.

[0007] The composition used to form the resin film may be a positive- or negative-type photosensitive composition. A resin film formed from the photosensitive composition may be patterned by photolithography to form contact holes. The composition may be a photo- or thermosetting composition or a thermosetting composition that is not alkali-soluble (photographically acceptable). SiH groups from the SiH group-containing compound may remain unreacted in the resin film after curing with heat and / or light.

[0008] The thin film transistor element is preferably 35 cm 2 / Vs or higher. [Effects of the Invention]

[0009] A composition containing a SiH group-containing compound is applied to an oxide semiconductor thin film and heated to obtain a thin film transistor element having high electron mobility. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view showing an example of the configuration of a bottom-gate thin-film transistor element. [Figure 2] FIG. 1 is a cross-sectional view showing an example of the configuration of a bottom-gate thin-film transistor element. [Figure 3] FIG. 1 is a cross-sectional view showing an example of the configuration of a top-gate thin-film transistor element. [Figure 4] FIG. 1 is a cross-sectional view showing an example of the configuration of a top-gate thin-film transistor element. DETAILED DESCRIPTION OF THE INVENTION

[0011] [Thin-film transistor element overview] Fig. 1 is a cross-sectional view showing an example of the configuration of a thin-film transistor element. The element shown in Fig. 1 is a bottom-gate element in which a gate insulating film 2 is formed on a gate layer 31, and an oxide semiconductor thin film 4 is formed on the gate insulating film 2. A pair of source and drain electrodes 51, 52 are formed on both ends of the oxide semiconductor thin film 4 so as to be in contact with the gate insulating film 2.

[0012] In fabricating the thin-film transistor element shown in FIG. 1, first, a gate layer 31 is formed on a substrate 1 such as glass, and then a gate insulating film 2 is formed thereon. Materials for the gate layer 31 include metal materials such as molybdenum, aluminum, copper, silver, gold, platinum, titanium, and alloys thereof. As the gate insulating film 2, for example, a silicon-based thin film such as a silicon oxide film, a silicon nitride film, or a silicon oxynitride film is formed by a plasma CVD method. The thickness of the gate insulating film is usually 50 to 300 nm. As the gate layer with an insulating film, a low-resistivity silicon substrate having a thermal oxide film formed on its surface may be used.

[0013] The oxide semiconductor thin film 4 is a semiconductor thin film made of a composite oxide containing two or more metal elements selected from the group consisting of indium, gallium, zinc, and tin. Specific examples of oxides include zinc-based oxide films such as Zn-Ga-O and Zn-Sn-O, and indium-based oxides such as In-Zn-O, In-Sn-O, In-Zn-Sn-O, In-Ga-Sn-O, In-Ga-Zn-O, and In-Ga-Zn-Sn-O. The oxide may contain metal elements other than In, Ga, Zn, and Sn (e.g., Al and W).

[0014] The oxide semiconductor thin film can be formed by a sputtering method, a liquid phase method, or the like. The film thickness of the oxide semiconductor thin film is about 20 to 150 nm. After forming the oxide semiconductor thin film 4, it is preferable to perform thermal annealing before forming the resin film 6 described below. Thermal annealing may also be performed after forming source and drain electrodes 51, 52 on the oxide semiconductor thin film 4. Thermal annealing of the oxide semiconductor thin film may be performed, for example, in an oxygen atmosphere at 200 to 400°C for about 10 minutes to 3 hours.

[0015] Source and drain electrodes 51 and 52 are formed on the oxide semiconductor thin film 4. The source and drain electrodes are formed so as to be electrically connected to the ends of the oxide semiconductor thin film 4, and a channel region 45 where no electrode is provided is formed between the pair of source and drain electrodes 51 and 52. Materials for the source and drain electrodes include molybdenum, aluminum, copper, silver, gold, platinum, titanium, and alloys thereof.

[0016] Methods for patterning the source and drain electrodes 51 and 52 include patterning by wet etching or dry etching, and patterning by mask film formation or lift-off.

[0017] A resin film 6 is formed so as to cover the oxide semiconductor thin film 4. The resin film 6 serves to protect the oxide semiconductor thin film 4 from the external environment and / or process damage. For example, in the embodiment shown in FIG. 1 , the resin film 6 is formed so as to cover the source and drain electrodes 51, 52, and functions as a protective film that protects the oxide semiconductor thin film 4 from the external environment.

[0018] A resin film may be formed between the oxide semiconductor thin film 4 and the source / drain electrodes 51, 52. In this case, the resin film can function as an etch stopper that prevents damage to the oxide semiconductor thin film 4 when the source / drain electrodes are patterned. When a resin film is formed as an etch stopper, the source / drain electrodes may be formed on the resin film after the resin film is formed.

[0019] The composition used to form the resin film contains a compound containing an SiH group (SiH group-containing compound). The amount of SiH groups in the SiH group-containing compound is preferably 0.1 mmol / g or more. The SiH group-containing compound may be a polymer. The composition may have negative or positive photosensitivity and may be patternable by photolithography. The composition may be a photo- or thermosetting composition or a thermosetting composition that is not alkali-soluble (photolithographically compatible).

[0020] A composition containing a SiH group-containing compound is applied onto the oxide semiconductor thin film 4, and the applied composition is heated to form the resin film 6. From the viewpoint of more effectively improving the characteristics of the thin film transistor element, in a bottom-gate element, it is preferable to apply the composition containing the SiH group-containing compound directly onto the channel region 45 of the oxide semiconductor thin film 4. When forming multiple resin films, it is preferable that the composition used to form the resin film in contact with the channel region 45 of the oxide semiconductor thin film 4 contains the SiH group-containing compound.

[0021] The heating temperature during resin film formation is preferably 190°C or higher. The composition may be heated in two or more stages. For example, heating (pre-baking) may be performed mainly to remove the solvent contained in the composition, and heating (post-baking) may be performed to thermally cure the resin component. When heating is performed in two or more stages, the highest temperature is preferably 190°C or higher. If the composition is photosensitive, exposure to light may be performed between pre-baking and post-baking.

[0022] Heating the composition containing the SiH group-containing compound on the oxide semiconductor thin film 4 tends to improve the electron mobility of the thin film transistor element. 2 / Vs or more is preferable, 40cm 2 / Vs or more is preferable, 50cm 2 / Vs or more, 55cm 2 / Vs or more or 60cm 2 / Vs or more.

[0023] Among oxide semiconductors, thin-film transistor elements using In-Ga-Zn-O (IGZO) thin films are known to exhibit high electron mobility, but the value is at most 10 to 20 cm 2 In the embodiment of the present invention, it is possible to realize a significantly higher electron mobility than conventional oxide semiconductor thin film transistor elements, and it is possible to provide a thin film transistor element having excellent characteristics such as switching speed.

[0024] The greater the amount of SiH groups in the composition and the higher the heating temperature, the greater the electron mobility of the device. While the reason why the formation of a resin film significantly improves electron mobility is unclear, one possible reason is that, in addition to the thermal annealing of the oxide semiconductor thin film, hydrogen generated from the SiH group-containing compound during heating diffuses into the oxide semiconductor thin film. Other factors that may contribute to the improvement in electron mobility include the diffusion of hydrogen generated from the SiH groups remaining unreacted after heating (curing) into the oxide semiconductor thin film, and passivation of the oxide semiconductor thin film by the SiH groups.

[0025] [SiH group-containing compound] The SiH group-containing compound contains at least one SiH group in the molecule, and preferably contains a polysiloxane structure. The "polysiloxane structure" refers to a structural skeleton having siloxane units Si-O-Si. The polysiloxane structure may be a cyclic polysiloxane structure. The "cyclic polysiloxane structure" refers to a cyclic molecular structural skeleton having siloxane units (Si-O-Si) as ring components.

[0026] The amount of SiH groups contained in the SiH group-containing compound is preferably 0.1 mmol / g or more, more preferably 0.3 mmol / g or more, even more preferably 0.5 mmol / g or more, and may be 0.7 mmol / g or more or 1.0 mmol / g or more. The upper limit of the amount of SiH groups contained in the SiH group-containing compound is not particularly limited, but is generally 30 mmol / g or less, and may be 20 mmol / g or less, 15 mmol / g or less, or 10 mmol / g or less.

[0027] The SiH group-containing compound may be a low-molecular-weight compound or a polymer. Examples of the low-molecular-weight compound containing SiH groups include the polysiloxane compounds having SiH groups described below.

[0028] From the viewpoint of the film-forming property and heat resistance of the resin film, the SiH group-containing compound is preferably a polymer containing a polysiloxane structure. The resin film-forming composition may contain both a low-molecular-weight compound containing an SiH group and a polymer containing an SiH group. The polysiloxane polymer may contain a polysiloxane structure in the main chain or in the side chain. When the polymer contains a polysiloxane structure in the main chain, the heat resistance of the resin film tends to be improved.

[0029] A polysiloxane polymer having SiH groups can be obtained, for example, by a hydrosilylation reaction between (α) a polysiloxane compound having at least two SiH groups per molecule and (β) a compound having at least two carbon-carbon double bonds (ethylenically unsaturated groups) per molecule that are reactive with SiH groups. The reaction between the compound (α) having multiple SiH groups and the compound having multiple ethylenically unsaturated groups crosslinks the multiple compounds (α), increasing the molecular weight of the polymer and tending to improve film-forming properties and the heat resistance of the resin film.

[0030] (Compound (α): Polysiloxane compound having SiH groups) Specific examples of the polysiloxane compound (α) having at least two SiH groups per molecule include a hydrosilyl group-containing polysiloxane having a linear structure, a polysiloxane having a hydrosilyl group at the molecular end, and a cyclic polysiloxane containing a hydrosilyl group. Polymers containing a cyclic polysiloxane structure tend to have better resin film formability and heat resistance than polymers containing only a chain polysiloxane structure.

[0031] The cyclic polysiloxane may have a polycyclic structure, and the polycyclic ring may have a polyhedral structure. In order to form a film with high heat resistance and mechanical strength, it is preferable to use a cyclic polysiloxane compound having at least two SiH groups per molecule as compound (α). Compound (α) preferably contains three or more SiH groups per molecule. From the viewpoint of heat resistance and light resistance, it is preferable that the group present on the Si atom is either a hydrogen atom or a methyl group.

[0032] Examples of hydrosilyl group-containing polysiloxanes having a linear structure include copolymers of dimethylsiloxane units, methylhydrogensiloxane units, and terminal trimethylsiloxy units, copolymers of diphenylsiloxane units, methylhydrogensiloxane units, and terminal trimethylsiloxy units, copolymers of methylphenylsiloxane units, methylhydrogensiloxane units, and terminal trimethylsiloxy units, and polysiloxanes whose ends are blocked with dimethylhydrogensilyl groups.

[0033] Polysiloxanes having hydrosilyl groups at the molecular terminals include polysiloxanes whose terminals are blocked with dimethylhydrogensilyl groups, and polysiloxanes containing dimethylhydrogensiloxane units (H(CH3)2SiO 1 / 2 units), and SiO2 units, SiO 3 / 2 units and at least one siloxane unit selected from the group consisting of SiO units.

[0034] Examples of cyclic polysiloxane compounds include 1,3,5,7-tetrahydrogen-1,3,5,7-tetramethylcyclotetrasiloxane, 1-propyl-3,5,7-trihydrogen-1,3,5,7-tetramethylcyclotetrasiloxane, 1,5-dihydrogen-3,7-dihexyl-1,3,5,7-tetramethylcyclotetrasiloxane, 1,3,5-trihydrogen-1,3,5-trimethylcyclosiloxane, 1,3,5,7,9-pentahydrogen-1,3,5,7,9-pentamethylcyclosiloxane, and 1,3,5,7,9,11-hexahydrogen-1,3,5,7,9,11-hexamethylcyclosiloxane.

[0035] The compound (α) may be a polycyclic polysiloxane having a polycyclic ring. The polycyclic ring may have a polyhedral structure. The polysiloxane having a polyhedral skeleton preferably has 6 to 24 Si atoms constituting the polyhedral skeleton, more preferably 6 to 10 Si atoms. A specific example of the polysiloxane having a polyhedral skeleton is silsesquioxane. The cyclic polysiloxane may be a silylated silicic acid having a polyhedral skeleton.

[0036] (Compound (β): Compound containing an ethylenically unsaturated group) Compound (β) contains two or more carbon-carbon double bonds reactive with SiH groups per molecule. Examples of the group containing a carbon-carbon double bond reactive with SiH groups (hereinafter, simply referred to as an "ethylenically unsaturated group" or "alkenyl group") include vinyl, allyl, methallyl, acryl, methacryl, 2-hydroxy-3-(allyloxy)propyl, 2-allylphenyl, 3-allylphenyl, 4-allylphenyl, 2-(allyloxy)phenyl, 3-(allyloxy)phenyl, 4-(allyloxy)phenyl, 2-(allyloxy)ethyl, 2,2-bis(allyloxymethyl)butyl, 3-allyloxy-2,2-bis(allyloxymethyl)propyl, and vinyl ether groups.

[0037] Specific examples of the compound (β) having two or more alkenyl groups in one molecule include diallyl phthalate, triallyl trimellitate, diethylene glycol bisallyl carbonate, trimethylolpropane diallyl ether, trimethylolpropane triallyl ether, pentaerythritol triallyl ether, pentaerythritol tetraallyl ether, 1,1,2,2-tetraallyloxyethane, diarylidene pentaerythritol, triallyl cyanurate, triallyl isocyanurate, diallyl monobenzyl isocyanurate, diallyl monomethyl isocyanurate, 1,2,4-trivinylcyclohexane, 1,4-butanediol divinyl ether, nonanediol divinyl ether, 1,4-cyclohexane dimethanol divinyl ether, triethylene glycol divinyl ether, trimethylolpropane trivinyl ether, and pentaerythritol tetravinyl ether. ether, diallyl ether of bisphenol S, divinylbenzene, divinylbiphenyl, 1,3-diisopropenylbenzene, 1,4-diisopropenylbenzene, 1,3-bis(allyloxy)adamantane, 1,3-bis(vinyloxy)adamantane, 1,3,5-tris(allyloxy)adamantane, 1,3,5-tris(vinyloxy)adamantane, dicyclopentadiene, vinylcyclohexene, 1,5-hexadiene, 1,9-decadiene, diallyl ether, bisphenol A diallyl ether, 2,5-diallylphenol allyl ether, and oligomers thereof, 1,2-polybutadiene (1,2 ratio of 10 to 100%, preferably 1,2 ratio of 50 to 100%), allyl ether of novolak phenol, allylated polyphenylene oxide, and other conventionally known epoxy resins in which all of the glycidyl groups have been replaced with allyl groups. Furthermore, compounds in which the allyl group in the above-exemplified compounds is replaced with a (meth)acryloyl group (for example, polyfunctional (meth)acrylates) can also be suitably used as compound (β).

[0038] Compound (β) may be a polysiloxane compound having two or more alkenyl groups. Specific examples of cyclic polysiloxane compounds having two or more alkenyl groups include 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane, 1-propyl-3,5,7-trivinyl-1,3,5,7-tetramethylcyclotetrasiloxane, 1,5-divinyl-3,7-dihexyl-1,3,5,7-tetramethylcyclotetrasiloxane, 1,3,5-trivinyl-1,3,5-trimethylcyclosiloxane, 1,3,5,7,9-pentavinyl-1,3,5,7,9-pentamethylcyclosiloxane, and 1,3,5,7,9,11-hexavinyl-1,3,5,7,9,11-hexamethylcyclosiloxane.

[0039] The compound (β) may be a compound having an alkenyl group at the end and / or side chain of a polymer chain such as polyether, polyester, polyarylate, polycarbonate, polyolefin, polyacrylic acid ester, polyamide, polyimide, or phenol-formaldehyde.

[0040] (Other starting materials) In addition to the above compounds (α) and (β), compounds containing only one functional group per molecule that participates in the hydrosilylation reaction may also be used as starting materials for the hydrosilylation reaction. The functional group that participates in the hydrosilylation reaction is an SiH group or an ethylenically unsaturated group. By using a compound containing only one functional group that participates in the hydrosilylation reaction, a specific functional group can be introduced at the end of a polymer.

[0041] A compound having a photopolymerizable functional group may be used as a starting material for the hydrosilylation reaction. Examples of photopolymerizable functional groups include cationically polymerizable functional groups and radically polymerizable functional groups. The term "cationically polymerizable functional group" refers to a functional group that undergoes polymerization and crosslinking due to the action of an acidic active substance generated from a photoacid generator when irradiated with active energy rays. Examples of active energy rays include visible light, ultraviolet light, infrared light, X-rays, α-rays, β-rays, and γ-rays. Examples of cationically polymerizable functional groups include epoxy groups, vinyl ether groups, oxetane groups, and alkoxysilyl groups. From the viewpoint of photosensitivity, epoxy groups are preferred as cationically polymerizable functional groups. Among epoxy groups, alicyclic epoxy groups or glycidyl groups are preferred from the viewpoint of stability. Alicyclic epoxy groups are particularly preferred due to their excellent photocationic polymerizability.

[0042] By using a compound having an alkenyl group and a cationically polymerizable functional group in one molecule as a starting material, the cationically polymerizable functional group can be introduced into the polymer. When the polymer has the cationically polymerizable functional group, the polymer is crosslinked by photocationic polymerization, which is expected to improve the mechanical strength and heat resistance of the resin film.

[0043] Specific examples of compounds having an alkenyl group and an epoxy group as a cationically polymerizable functional group in one molecule include vinylcyclohexene oxide, allyl glycidyl ether, diallyl monoglycidyl isocyanurate, and monoallyl diglycidyl isocyanurate.

[0044] The polysiloxane polymer may have multiple cationically polymerizable functional groups in one molecule. When the polymer has multiple cationically polymerizable functional groups in one molecule, the crosslinking density tends to be increased, and the heat resistance of the resin film tends to be improved. The multiple cationically polymerizable functional groups may be the same or two or more different functional groups.

[0045] The polysiloxane polymer may be alkali-soluble. This can be achieved by introducing alkali-solubility-imparting groups into the polymer. When a polymer has both photopolymerizable functional groups and alkali-solubility-imparting groups, it exhibits alkali solubility before photocuring and becomes alkali-insoluble after photocuring, allowing it to be used as a negative-tone photosensitive resin. Examples of alkali-solubility-imparting groups (acidic groups) include phenolic hydroxyl groups, carboxyl groups, N-substituted isocyanuric acid, and N,N'-disubstituted isocyanuric acid. Alkali-soluble polymers can be obtained by using a compound containing an acidic group and an alkenyl group and / or an SiH group as the starting material for the hydrosilylation reaction.

[0046] The polysiloxane polymer may be one that exhibits alkali solubility by eliminating the protecting groups in the presence of acid. A polymer that exhibits alkali solubility by eliminating the protecting groups in the presence of acid can be used as a positive-tone photosensitive resin because the protecting groups are removed (deprotected) by reaction with the acid generated from the photoacid generator, increasing the alkali solubility.

[0047] Examples of acidic groups include phenolic hydroxyl groups, carboxy groups, N-substituted isocyanuric acids, and N,N'-disubstituted isocyanuric acids. Examples of protecting groups for phenolic hydroxyl groups include tert-butoxycarbonyl groups and trialkylsilyl groups. For example, a phenolic hydroxyl group can be protected with a tert-butoxycarbonyl group by a reaction using a Boc reagent. The alkyl group in the trialkylsilyl group used as a protecting group for a phenolic hydroxyl group is preferably an alkyl group having 1 to 6 carbon atoms, and a methyl group is particularly preferred, from the viewpoint of ease of deprotection with an acid. A phenolic hydroxyl group can be protected with a trimethylsilyl group by a reaction using a silylating agent such as hexamethyldisilazane or trimethylchlorosilane. The acidic group (NH group) of N-substituted isocyanuric acids and N,N'-disubstituted isocyanuric acids can also be protected with the same protecting group as the phenolic hydroxyl group. Examples of protecting groups for carboxylic acids include tertiary alkyl esters and acetals. Examples of the tertiary alkyl group in the tertiary alkyl ester of carboxylic acid include a tert-butyl group, an adamantyl group, a tricyclodecyl group, and a norbornyl group.

[0048] By using a compound having a structure with a protecting group that is eliminated in the presence of acid and containing an alkenyl group and / or an SiH group as the starting material for the hydrosilylation reaction, the protecting group is eliminated in the presence of acid, thereby producing an alkali-soluble polysiloxane polymer.

[0049] (hydrosilylation reaction) The order and method of the hydrosilylation reaction are not particularly limited. The hydrosilylation reaction may be carried out by charging all of the starting materials into one pot and carrying out polymerization, or by charging the raw materials in multiple batches and carrying out the reaction in multiple stages.

[0050] In the hydrosilylation reaction, the ratio B / A of the total amount of alkenyl groups A to the total amount of SiH groups B in the starting materials is preferably greater than 1. In the hydrosilylation reaction, alkenyl groups and SiH groups react in a ratio of 1:1. If B / A is greater than 1 and there is an excess of SiH groups relative to alkenyl groups, a polysiloxane polymer with unreacted SiH groups will be obtained.

[0051] The electron mobility of the thin film transistor element tends to increase as the amount of SiH groups in the polysiloxane polymer in the resin film 6 formed on the oxide semiconductor thin film 4 increases. Therefore, B / A is preferably 1.1 or more, more preferably 1.5 or more, even more preferably 2 or more, and may be 3 or more or 5 or more. From the viewpoint of increasing the SiH group content of the polymer, a larger B / A is preferable. On the other hand, if the amount of unreacted remaining SiH groups is excessively large, the stability of the resin film may decrease, so B / A is preferably 30 or less, more preferably 20 or less, and may be 15 or less or 10 or less.

[0052] The hydrosilylation reaction may be carried out using a hydrosilylation catalyst such as chloroplatinic acid, a platinum-olefin complex, or a platinum-vinylsiloxane complex. The hydrosilylation catalyst may be used in combination with a co-catalyst. The amount of the hydrosilylation catalyst added is not particularly limited, but is preferably 10 moles relative to the total number (number of moles) of alkenyl groups contained in the starting material. -8 ~10 -1 times, more preferably 10 -6 ~10 -2 It's double.

[0053] The reaction temperature for hydrosilylation may be set appropriately, and is preferably 30 to 200°C, more preferably 50 to 150°C. The volume concentration of oxygen in the gas phase during the hydrosilylation reaction is preferably 3% or less. From the viewpoint of promoting the hydrosilylation reaction by adding oxygen, the gas phase may contain approximately 0.1 to 3% by volume of oxygen.

[0054] A solvent may be used in the hydrosilylation reaction. Examples of the solvent include hydrocarbon solvents such as benzene, toluene, hexane, and heptane; ether solvents such as tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, and diethyl ether; ketone solvents such as acetone and methyl ethyl ketone; and halogenated solvents such as chloroform, methylene chloride, and 1,2-dichloroethane. Toluene, tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, and chloroform are preferred because they are easily removed by distillation after the reaction. A gelation inhibitor may be used in the hydrosilylation reaction, if necessary.

[0055] The amount of SiH groups contained in the polysiloxane polymer is preferably 0.1 mmol / g or more, more preferably 0.3 mmol / g or more, even more preferably 0.5 mmol / g or more, and may be 0.7 mmol / g or more or 1.0 mmol / g or more. The upper limit of the amount of SiH groups contained in the polymer is not particularly limited, but is generally 30 mmol / g or less, and may be 20 mmol / g or less, 15 mmol / g or less, or 10 mmol / g or less. As described above, the amount of residual SiH groups in the polymer can be adjusted to a desired range by adjusting the type of starting material and the ratio of the amount of SiH groups to the amount of alkenyl groups.

[0056] [Composition] The composition used for forming a resin film on an oxide semiconductor thin film may contain, in addition to the SiH group-containing compound, a polymer not containing an SiH group, a crosslinking agent, a thermosetting resin, a photoacid generator, a sensitizer, a solvent, and the like.

[0057] <Crosslinking agent> The composition may contain a crosslinking agent reactive with the SiH group-containing compound. The crosslinking agent may be one that exhibits reactivity by photoreaction or one that exhibits reactivity by heat.

[0058] For example, if a compound having two or more alkenyl groups in one molecule is used as a crosslinking agent, the alkenyl groups will undergo a hydrosilylation reaction with the SiH groups of the SiH group-containing compound upon heating, thereby introducing a crosslinked structure. Specific examples of compounds having two or more alkenyl groups in one molecule include those exemplified above as examples of compound (β).

[0059] When the SiH group-containing compound has cationic polymerization properties, if a compound having two or more alkenyl groups in one molecule is used as a crosslinking agent, the SiH group-containing compound and the crosslinking agent will react with each other upon exposure to light, thereby hardening the resin film. As a photocationically polymerizable crosslinking agent, a compound having two or more alicyclic epoxy groups in one molecule is preferred. Specific examples of compounds having two or more alicyclic epoxy groups per molecule include 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate ("Celloxide 2021P" manufactured by Daicel), ε-caprolactone-modified 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate ("Celloxide 2081" manufactured by Daicel), bis(3,4-epoxycyclohexylmethyl)adipate, an epoxy-modified linear siloxane compound of the following formula S1 ("X-40-2669" manufactured by Shin-Etsu Chemical), and an epoxy-modified cyclic siloxane compound of the following formula S2 ("KR-470" manufactured by Shin-Etsu Chemical).

[0060] [ka]

[0061] <Thermosetting resin> The composition may contain a polymerizable compound (thermosetting resin) that is not reactive with the SiH group-containing compound and can be thermoset either alone or by reacting with other compounds. Examples of thermosetting resins include epoxy resins, oxetane resins, isocyanate resins, blocked isocyanate resins, bismaleimide resins, bisallylnadiimide resins, acrylic resins, allyl-cured resins, and unsaturated polyester resins. The thermosetting resin may be a side-chain reactive group-type thermosetting polymer having a reactive group such as an allyl group, a vinyl group, an alkoxysilyl group, or a hydrosilyl group in the side chain or at the end of the polymer chain.

[0062] <Photoacid generator> The photosensitive resin film-forming composition may contain a photoacid generator. When the photoacid generator is irradiated with active energy rays such as ultraviolet light, an acid is generated. In a cationically polymerizable composition (e.g., a negative-type photosensitive composition), the photoacid generator acts as a polymerization initiator, and curing proceeds through cationic polymerization. In a positive-type photosensitive composition, the action of the acid generated from the photoacid generator causes the protective group bonded to the alkali-solubility-imparting group (acidic group) to be released, thereby increasing alkali solubility.

[0063] The photoacid generator contained in the photosensitive composition is not particularly limited as long as it generates a Lewis acid upon exposure. Specific examples of the photoacid generator include ionic photoacid generators such as sulfonium salts, iodonium salts, ammonium salts, and other onium salts; and nonionic photoacid generators such as imide sulfonates, oxime sulfonates, and sulfonyldiazomethanes.

[0064] The content of the photoacid generator in the photosensitive composition is preferably 0.1 to 20 parts by weight, more preferably 0.1 to 15 parts by weight, and even more preferably 0.5 to 10 parts by weight, per 100 parts by weight of the resin content of the composition.

[0065] <Sensitizer> The photosensitive resin film-forming composition may contain a sensitizer. The use of a sensitizer improves the exposure sensitivity during patterning. Examples of sensitizers include naphthalene-based compounds, anthracene-based compounds, and thioxanthone-based compounds. Among these, anthracene-based sensitizers are preferred because of their excellent photosensitizing effect. Specific examples of the anthracene-based sensitizer include anthracene, 2-ethyl-9,10-dimethoxyanthracene, 9,10-dimethylanthracene, 9,10-dibutoxyanthracene (DBA), 9,10-dipropoxyanthracene, 9,10-diethoxyanthracene, 9,10-bis(octanoyloxy)anthracene, 1,4-dimethoxyanthracene, 9-methylanthracene, 2-ethylanthracene, 2-tert-butylanthracene, 2,6-di-tert-butylanthracene, and 9,10-diphenyl-2,6-di-tert-butylanthracene.

[0066] The content of the sensitizer in the composition is not particularly limited and may be adjusted as appropriate within a range that allows the sensitizing effect to be exhibited. From the viewpoint of the balance between the curability and physical properties of the resin film, the content is preferably 0.01 to 20 parts by weight, more preferably 0.1 to 15 parts by weight, and even more preferably 0.5 to 10 parts by weight, per 100 parts by weight of the resin content of the composition.

[0067] <Solvent> The resin film-forming composition can be prepared by dissolving or dispersing the above components in a solvent. Any solvent can be used as long as it can dissolve the SiH group-containing compound and other components. Specific examples include hydrocarbon solvents such as benzene, toluene, hexane, and heptane; ether solvents such as tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, and diethyl ether; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; glycol solvents such as propylene glycol-1-monomethyl ether-2-acetate (PGMEA), diethylene glycol dimethyl ether, diethylene glycol ethyl methyl ether, and ethylene glycol diethyl ether; and halogenated solvents such as chloroform, methylene chloride, and 1,2-dichloroethane. From the viewpoint of film formation stability, propylene glycol-1-monomethyl ether-2-acetate and diethylene glycol dimethyl ether are preferred. The amount of solvent used can be determined appropriately.

[0068] <Other ingredients> The resin film-forming composition may contain other resin components, additives, etc., besides those mentioned above. For example, the resin film-forming composition may contain various thermoplastic resins for the purpose of property modification, etc. Examples of thermoplastic resins include acrylic resins, polycarbonate resins, cycloolefin resins, olefin-maleimide resins, polyester resins, polyethersulfone resins, polyarylate resins, polyvinyl acetal resins, polyethylene resins, polypropylene resins, polystyrene resins, polyamide resins, silicone resins, fluororesins, and rubber-like resins such as natural rubber and EPDM. The thermoplastic resin may have crosslinkable groups such as epoxy groups, amino groups, radically polymerizable unsaturated groups, carboxy groups, isocyanate groups, hydroxy groups, and alkoxysilyl groups.

[0069] In addition to the above, the resin film-forming composition may contain an adhesion improver, a coupling agent such as a silane coupling agent, an anti-degradation agent, a hydrosilylation reaction inhibitor, a polymerization inhibitor, a polymerization catalyst (crosslinking accelerator), a release agent, a flame retardant, a flame retardant aid, a surfactant, an antifoaming agent, an emulsifier, a leveling agent, an anti-repellent agent, an ion trapping agent, a thixotropy imparting agent, a tackifier, a storage stability improver, a light stabilizer, a thickener, a plasticizer, a reactive diluent, an antioxidant, a heat stabilizer, an electrical conductivity imparting agent, an antistatic agent, a radiation shielding agent, a nucleating agent, a phosphorus-based peroxide decomposer, a lubricant, a metal deactivator, a thermal conductivity imparting agent, a physical property adjuster, and the like.

[0070] The amount of SiH groups in the resin content of the resin film-forming composition is preferably 0.1 mmol / g or more, more preferably 0.3 mmol / g or more, even more preferably 0.5 mmol / g or more, and may be 0.7 mmol / g or more or 1.0 mmol / g or more.

[0071] [Resin film formation] A composition containing a SiH group-containing compound is applied onto the oxide semiconductor thin film 4 and heated to form the resin film 6. As described above, in the formation of a bottom-gate type element, it is preferable to apply the composition directly onto the channel region 45 of the oxide semiconductor thin film 4. The method for applying the composition is not particularly limited as long as it allows for uniform application, and common coating methods such as spin coating, slit coating, and screen coating can be used.

[0072] After the composition is applied, it is heated to form the resin film 6. The thickness of the resin film 6 is, for example, about 0.2 to 6 μm, and may be about 0.5 to 3 μm.

[0073] As mentioned above, the heating temperature is preferably 190°C or higher. The higher the heating temperature, the greater the electron mobility of the device tends to be. The heating temperature is more preferably 200°C or higher, even more preferably 210°C or higher, and may be 220°C or higher. An excessively high heating temperature may cause thermal degradation of the oxide semiconductor thin film or resin film. Therefore, the heating temperature is preferably 450°C or lower, more preferably 400°C or lower, and may be 350°C or lower or 300°C or lower. The heating time at a temperature of 190°C or higher is preferably 5 minutes or longer, more preferably 10 minutes or longer. The upper limit of the heating time is not particularly limited, but from the viewpoints of suppressing thermal degradation and production efficiency, it is preferably 5 hours or shorter, more preferably 3 hours or shorter, and may be 1 hour or shorter. As mentioned above, the composition may be heated in two or more stages.

[0074] Heating to 190°C or higher causes the SiH groups in the SiH group-containing compound to react with each other and harden. Furthermore, when the composition contains a compound with multiple alkenyl groups as a crosslinker, heating causes the SiH groups to undergo a hydrosilylation reaction with the alkenyl groups of the crosslinker, which causes hardening (crosslinking) to proceed, tending to improve the insulating properties, heat resistance, solvent resistance, etc. of the resin film.

[0075] 2, contact holes 91, 92 may be formed in the resin film 6 to ensure electrical connection with the source / drain electrodes 51, 52. If the resin film-forming composition is photosensitive, it is preferable to perform exposure and alkaline development before post-baking, and then pattern the resin film by photolithography.

[0076] Before exposure, heating (pre-baking) may be performed to dry the solvent. The heating temperature can be set appropriately, but is preferably 50 to 150°C. Photosensitive compositions containing thermosetting components may have poor developability as they are cured by heating. Therefore, the heating temperature in pre-baking is preferably 120°C or lower.

[0077] The light source for exposure may be selected depending on the wavelength sensitivity of the photoacid generator and sensitizer contained in the photosensitive composition. Typically, a light source having a wavelength in the range of 200 to 450 nm (e.g., a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, a high-power metal halide lamp, a xenon lamp, a carbon arc lamp, or a light-emitting diode) is used.

[0078] The exposure dose is not particularly limited, but is preferably 1 to 5000 mJ / cm 2 is preferred, and 5 to 1000 mJ / cm 2 More preferably, 10 to 500 mJ / cm 2 If the exposure dose is too low, curing may be insufficient, resulting in a decrease in pattern contrast, whereas if the exposure dose is too high, the takt time may increase, resulting in an increase in manufacturing costs.

[0079] A general photomask can be used for the pattern exposure. For a negative photosensitive composition, a pattern mask capable of blocking light from the areas where the contact holes 91 and 92 are to be formed is used. For a positive photosensitive composition, a pattern mask having openings formed therein so that the areas where the contact holes 91 and 92 are to be formed are selectively exposed is used.

[0080] The exposed coating film is brought into contact with an alkaline developer by immersion, spraying, or other methods to dissolve and remove the coating film, thereby achieving patterning. In a negative-type photosensitive composition, the exposed areas are photocured and no longer exhibit alkaline solubility, so that the unexposed areas of the film are selectively removed by alkaline development. In a positive-type photosensitive composition, the acid generated by light irradiation of the photoacid generator increases the alkaline solubility, so that the exposed areas of the film are selectively removed.

[0081] The alkaline developer may be any commonly used one without any particular limitations. Specific examples of alkaline developers include organic alkaline aqueous solutions such as tetramethylammonium hydroxide (TMAH) aqueous solution and choline aqueous solution, and inorganic alkaline aqueous solutions such as potassium hydroxide aqueous solution, sodium hydroxide aqueous solution, potassium carbonate aqueous solution, sodium carbonate aqueous solution, and lithium carbonate aqueous solution. The alkaline concentration of the developer is preferably 0.01 to 25% by weight, more preferably 0.1 to 10% by weight, and even more preferably 0.3 to 5% by weight. The developer may contain a surfactant or the like for the purpose of adjusting the dissolution rate, etc.

[0082] By carrying out the above-mentioned heating (post-baking) after development, the resin film is hardened and the electron mobility of the device is improved. The method of forming contact holes 91, 92 by photolithography using a negative or positive photosensitive composition is less likely to damage electrodes 51, 52 or oxide semiconductor thin film 4 during contact hole formation, and can contribute to the formation of devices with excellent characteristics.

[0083] The method for forming the contact holes is not limited to photolithography, and the contact holes may be formed by techniques such as dry etching, mechanical drilling, laser processing, and lift-off. Furthermore, depending on the structure of the element, it is not always necessary to form contact holes in the resin film. When patterning by photolithography is not required, the resin film-forming composition may be a photo- or thermosetting composition or a thermosetting composition that is not alkali-soluble.

[0084] The resin film after curing by heat and / or light may contain unreacted SiH groups from the SiH group-containing compound. The amount of SiH groups in the cured resin film may be 0.001 mmol / g or more, 0.01 mmol / g or more, or 0.05 mmol / g or more.

[0085] As described above, in this embodiment, a thin-film transistor element with high electron mobility is obtained by applying a composition containing a SiH group-containing compound onto an oxide semiconductor thin film and heating it to form a resin film. The configuration of the thin-film transistor element is not limited to the form shown in FIGS. 1 and 2 . For example, as described above, by forming a resin film on the oxide semiconductor thin film before forming the source and drain electrodes 51 and 52, the resin film can be made to function as an etch stopper. This embodiment can also be applied to a thin-film transistor element in which source and drain electrodes are formed in contact with the oxide semiconductor thin film through contact holes provided in the resin film.

[0086] The thin film transistor element is not limited to a bottom gate type in which the gate layer is arranged closer to the substrate than the semiconductor layer, but may also be a top gate type in which the gate layer is arranged on the semiconductor layer (the surface opposite to the substrate).

[0087] FIG. 3 is a cross-sectional view showing an example of the configuration of a top-gate thin-film transistor element, in which an oxide semiconductor thin film 4 is provided on a substrate 1, and a gate insulating film 2 and a gate layer 31 are provided on a partial region thereof to form a channel region 46. In FIG. 3, the gate layer 31 is provided over the entire gate insulating film 2, but the gate layer may also be provided on a partial region of the gate insulating film. Source and drain electrodes 51 and 52 are provided on the oxide semiconductor thin film 4 and spaced apart from the gate layer 31. The source and drain electrodes 51 and 52 are spaced apart from the gate layer 31 but may be in contact with the gate insulating film 2. The materials, formation methods, film thicknesses, etc. of the gate insulating film 2, gate layer 31, oxide semiconductor thin film 4, and source and drain electrodes 51 and 52 are the same as those of the bottom-gate type.

[0088] Even in a top-gate type element, the characteristics (e.g., electron mobility) of the thin film transistor element tend to be improved by applying a composition containing a SiH group-containing compound so as to cover the oxide semiconductor thin film 4, and then heating to form a resin film 6. In this configuration, the resin film 6 functions not only as a protective film for the oxide semiconductor thin film 4, but also as an interlayer insulating film that insulates between electrodes.

[0089] 3, in the channel region 46, the resin film 6 is not in contact with the oxide semiconductor thin film 4, but as in the case of the bottom-gate element, forming the resin film 6 using a composition containing SiH improves the characteristics of the thin-film transistor element. Although the reason for this is not clear, it is presumed that the formation of the resin film 6 in a partial region on the oxide semiconductor thin film 4 has the effect of improving the film quality of the bulk of the oxide semiconductor thin film 4, and that hydrogen generated from the SiH group-containing compound in the resin film 6 diffuses into the region of the oxide semiconductor thin film 4 that is not in contact with the resin film 6, thereby contributing to the improvement in film quality.

[0090] In a top-gate element, the resin film 6 only needs to cover the oxide semiconductor thin film 4 in the regions between the electrode 51 and the gate layer 31 and between the electrode 52 and the gate layer 31, and the resin film 6 may not be provided on part or all of the regions of the source and drain electrodes 51 and 52 and part or all of the region on the gate layer 31. For example, as in the case shown in FIG. 2, contact holes may be provided in the resin film 6 on the source and drain electrodes 51 and 52. Alternatively, as in the embodiment shown in FIG. 4, after the resin film 6 is formed, contact holes 93 and 94 may be formed in the resin film 6, and the source and drain electrodes 53 and 54 may be formed so as to contact the oxide semiconductor thin film 4 through the contact holes.

[0091] The thin-film transistor element may have a double-gate structure including a bottom gate layer closer to the substrate than the semiconductor layer and a top gate layer disposed on the semiconductor layer (on the side opposite the substrate). A double-gate element includes a bottom gate insulating film between the semiconductor layer and the bottom gate layer, a top gate insulating layer between the semiconductor layer and the top gate layer, and the above-mentioned resin film in contact with the semiconductor layer. A double-gate element can be manufactured, for example, by forming a bottom gate layer, a bottom gate insulating film, and a semiconductor layer in this order on a substrate, similar to the formation of a bottom-gate element, and then forming a top gate insulating film, a top gate layer, and a resin film (interlayer filler film) on the semiconductor layer, similar to the formation of a top-gate element. [Example]

[0092] The present invention will be described in more detail below based on examples, but the present invention is not limited to the following examples.

[0093] [Synthesis of polysiloxane polymers] <Synthesis Example 1> Solution 1 was prepared by dissolving 40 g of diallyl isocyanuric acid and 29 g of diallyl monomethyl isocyanuric acid in 264 g of dioxane, and adding 0.02 g of a xylene solution of platinum vinyl siloxane complex (Pt-VTSC-3X manufactured by Umicore Precious Metals Japan, platinum content 3 wt%). A solution of 88 g of 1,3,5,7-tetrahydrogen-1,3,5,7-tetramethylcyclotetrasiloxane in 176 g of toluene was heated to 105°C, and the above solution 1 was added dropwise over 3 hours in a nitrogen atmosphere containing 3% oxygen. 30 minutes after the completion of the dropwise addition, 1 The reaction rate of the alkenyl groups was confirmed to be 95% or more by 1 H-NMR.

[0094] To the reaction solution, 124 g of a solution (62 g of 1-vinyl-3,4-epoxycyclohexane) prepared by mixing 1-vinyl-3,4-epoxycyclohexane and toluene in a weight ratio of 1:1 was added dropwise over 1 hour. 30 minutes after the completion of the addition, 1The reaction rate of the alkenyl groups was confirmed to be 95% or more by H-NMR. The reaction was then terminated by cooling, and the toluene and dioxane were distilled off under reduced pressure to obtain Polymer A. 1 The amount of SiH groups measured by 1 H-NMR was 1.1 mmol / g.

[0095] <Synthesis Example 2> Polymer B having 0.3 mmol / g of SiH groups was obtained in the same manner as in Synthesis Example 1, except that the amount of the toluene solution of 1-vinyl-3,4-epoxycyclohexane added was changed to 160 g (the amount of 1-vinyl-3,4-epoxycyclohexane added was 80 g).

[0096] <Synthesis Example 3> 5 g of bisphenol was dissolved in 20 g of tetrahydrofuran (THF), and then 2.5 g of hexamethyldisilazane was added and reacted at room temperature for 2 hours. THF and the reaction residue were distilled off under reduced pressure to obtain 6.5 g of reaction product 2. Reaction product 2 is diallyl bisphenol S in which the hydroxyl group is protected with a trimethylsilyl group. 1 1 H-NMR confirmed the absence of peaks derived from trimethylsilyl groups and peaks derived from hydroxyl groups.

[0097] 3 g of 1,3,5,7-tetrahydrogen-1,3,5,7-tetramethylcyclotetrasiloxane was dissolved in 20 g of toluene, and the gas phase was replaced with nitrogen and then heated to 100°C. A mixture containing 5 g of the above-mentioned reactant 2, 1.5 g of 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane, 0.7 mg of a xylene solution of platinum vinylsiloxane complex ("Pt-VTSC-3X" manufactured by Umicore Precious Metals Japan), and 5 g of toluene was added dropwise to this solution over 45 minutes. 30 minutes after the completion of the addition, 1 The reaction rate of the alkenyl groups was confirmed to be 95% or more by H-NMR. The reaction was then terminated by cooling, and the toluene was distilled off under reduced pressure to obtain Polymer C, which was a colorless, transparent liquid. 1 The amount of SiH groups measured by 1 H-NMR was 3.0 mmol / g.

[0098] <Synthesis Example 4> 72.4 g of 1,3,5,7-tetramethylcyclotetrasiloxane was dissolved in 72 g of toluene, and the gas phase was replaced with nitrogen and then heated to 105°C. A mixture containing 10 g of triallyl isocyanurate, 6.3 mg of a xylene solution of platinum vinylsiloxane complex ("Pt-VTSC-3X" manufactured by Umicore Precious Metals Japan), and 10 g of toluene was added dropwise to this solution over 45 minutes. 60 minutes after the completion of the addition, 1 The reaction rate of the alkenyl groups was confirmed to be 95% or more by H-NMR. The reaction was then terminated by cooling, and the toluene was distilled off under reduced pressure to obtain Polymer D, which was a colorless, transparent liquid. 1 The amount of SiH groups measured by 1 H-NMR was 9.2 mmol / g.

[0099] [Preparation of insulating film-forming composition] Photo- and thermosetting resin compositions 1 to 7 were prepared according to the formulations (weight ratios) shown in Table 1. Compositions 1 and 2 are negative-type photosensitive compositions, composition 3 is a positive-type photosensitive composition, and composition 4 is a photo- and thermosetting composition that does not exhibit photolithography properties (alkali solubility).

[0100] Composition 5 is a composition containing, as resin components, an alkali-soluble acrylic resin ("Pholette ZAH110" manufactured by Soken Chemical & Engineering Co., Ltd.) and an epoxy compound represented by the following formula ("Celloxide 2021P" manufactured by Daicel Corporation).

[0101] [ka]

[0102] Composition 6 is a composition containing an epoxy siloxane compound represented by the following formula (KR-470: "KR-470" manufactured by Shin-Etsu Chemical Co., Ltd.) as a resin component, and Composition 6 is a composition containing triglycidyl isocyanurate (TEPIC) as a resin component.

[0103] [ka]

[0104] Details of each component shown in Table 1 are as follows: TAIC: Triallyl isocyanurate Photoacid generator: San-Apro "CPI210S" (sulfonium salt photoacid generator) Sensitizer: 9,10-dibutoxyanthracene Pt catalyst: Umicore Precious Metals Japan "Pt-VTSC-3X" Solvent: Propylene glycol monomethyl ether acetate

[0105] [Table 1]

[0106] [Fabrication of thin-film transistor elements] <Reference Example 1: Bottom-gate type device without a protective film> A 70-nm-thick oxide (IGZO) semiconductor thin film was sputtered onto a 100-nm-thick, highly doped p-type Si substrate with a thermal oxide film using a sputtering system (Shimadzu Emit "SENTRON") with an In:Ga:Zn=2:2:1 alloy target at a pressure of 0.6 Pa, an Ar flow rate of 19.1 sccm, and an O2 flow rate of 0.9 sccm. A resist pattern was formed on the oxide semiconductor thin film, and wet etching was performed with 0.05 mol% hydrochloric acid. The resist was then removed by acetone and methanol washing, resulting in patterning of the oxide semiconductor thin film. A resist pattern was then formed on top of the sputtered Pt source electrode with a thickness of 20 nm and a Mo drain electrode with a thickness of 80 nm. The electrodes were then patterned by lift-off. The thin film was then thermally annealed at 290°C under oxygen flow (O2 flow rate: 5 sccm) for 1 hour to obtain a bottom-gate thin-film transistor.

[0107] <Examples 1 to 3> In the same manner as in Reference Example 1, the oxide semiconductor thin film, source electrode, and drain electrode were formed, patterned, and subjected to thermal annealing. Compositions 1 to 3 in Table 1 were applied by spin coating to the surface on which the oxide semiconductor thin film and the electrodes were formed so that the film would have a thickness of 1 μm after drying, and the film was heated on a hot plate at 110°C for 2 minutes. Exposure was performed (cumulative light intensity: 100 mJ / cm) through a photomask with a 100 μm hole pattern (negative pattern in Examples 1 and 2, positive pattern in Example 3) using a mask aligner ("MA-10" manufactured by Mikasa). 2 The resulting substrate was developed with a 2.38% TMAH developer to form 100 μm diameter contact holes on the source and drain electrodes, followed by post-baking at 230°C for 30 minutes to obtain a thin-film transistor device with a protective film.

[0108] Example 4 As in Examples 1 to 3, Composition 4 in Table 1 was applied by spin coating to the surface on which the oxide semiconductor thin film and the electrode were to be formed so that the film would have a dry thickness of 1 μm, and the applied film was heated on a hot plate at 110° C. for 2 minutes, and then heat-cured for 30 minutes at 230° C. Thereafter, the protective film on the source electrode and the drain electrode was removed by dry etching to form contact holes.

[0109] <Comparative Examples 1 to 3> As in Examples 1 to 3, compositions 5 to 7 in Table 1 were applied by spin coating to the surfaces on which the oxide semiconductor thin film and electrodes were to be formed so that the film thickness after drying was 1 μm, and the applied film was heated on a hot plate at 110°C for 2 minutes. After exposure using a mask aligner without using a photomask, the film was cured by heating at 230°C for 30 minutes. Thereafter, contact holes were formed by dry etching as in Example 4.

[0110] <Example 5 and Comparative Examples 4 and 5> A thin film transistor element provided with a protective film having contact holes was obtained in the same manner as in Example 1, except that the post-bake temperature of the protective film was changed as shown in Table 2.

[0111] <Reference Example 2: Top-gate type element without interlayer insulating film> A 70-nm-thick IGZO semiconductor thin film was formed and patterned on a 100-nm-thick thermally oxidized Si substrate under the same conditions as in Reference Example 1. A 200-nm-thick SiO2 layer (gate insulating film) and a 100-nm-thick Al layer (gate layer) were sequentially formed by sputtering. A resist pattern was formed on the Al layer, and the Al layer was wet-etched using a mixed acid (80 wt% phosphoric acid, 5 wt% nitric acid, 5 wt% acetic acid, and the remainder was water). The resist was then removed by acetone and methanol washing. The SiO2 layer was then patterned by inductively coupled plasma reactive ion etching (ICP-RIE) using CF4 as the etching gas, followed by Ar plasma treatment. A resist pattern was then formed, and a 20-nm-thick Pt source electrode and an 80-nm-thick Mo drain electrode were formed by sputtering. The electrodes were then patterned by lift-off. A thermal annealing treatment was then performed for 1 hour at 290°C under an oxygen flow (O2 flow rate: 5 sccm) to obtain a top-gate thin-film transistor device.

[0112] Example 6 The oxide semiconductor thin film, gate insulating film, gate layer, source electrode, and drain electrode were formed and patterned, and a thermal annealing treatment was performed in the same manner as in Reference Example 2. Composition 1 in Table 1 was applied by spin coating to the surface on which the oxide semiconductor thin film and electrodes were formed so that the film would have a thickness of 1 μm after drying, and the resulting film was heated on a hot plate at 110°C for 2 minutes. Thereafter, contact holes were formed and post-baking (at 230°C for 30 minutes) was performed under the same conditions as in Example 1, to obtain a thin-film transistor element equipped with an interlayer insulating film.

[0113] <Comparative Example 6> As in Example 6, Composition 5 in Table 1 was applied by spin coating to the surface on which the oxide semiconductor thin film and electrode were to be formed so that the film would have a dry thickness of 1 μm, and then heated on a hot plate at 110° C. for 2 minutes. After exposure using a mask aligner without using a photomask, the film was heat-cured at 230° C. for 30 minutes. Thereafter, contact holes were formed by dry etching as in Example 4.

[0114] [evaluation] Using a semiconductor parameter analyzer (Agilent Technologies, "Agilent 4156"), the current transfer characteristics of the thin-film transistor elements of the above-mentioned Reference Example, Examples, and Comparative Examples were measured under conditions of drain voltage: 5 V, substrate temperature: room temperature, and gate voltage varying from -20 V to +20 V. Electron mobility, threshold voltage, and ON / OFF current ratio were calculated using the following methods.

[0115] (threshold voltage) The X-intercept voltage of the tangent line between the saturated regions of the current transfer characteristics is the threshold voltage V th It was decided.

[0116] (electron mobility) The electron mobility μ was calculated in the gate voltage range of −20 V to +20 V using the following formula, and the maximum value in the measurement range was taken as the electron mobility of the device. μ=2(L×I d ) / {W×Cox×(V g -V th ) 2} L: channel length; 10 μm W: Channel width: 90 μm Cox: Capacitance per unit area of ​​gate insulating film: 3.45×10 -8 F / cm 2 V g : Gate voltage V th : Threshold voltage I d : Source-drain current

[0117] (ON / OFF current ratio) The maximum current value in the saturation region of the current transfer characteristic curve is the on-state current I on The off-state current I off was calculated from the minimum current in the off state. on / I off was taken as the ON / OFF current ratio.

[0118] Table 2 shows the types of compositions and amounts of SiH groups used to form the protective films of the examples and comparative examples, the conditions for heat curing (post-baking) when forming the protective films, and the evaluation results of the thin film transistor elements.

[0119] [Table 2]

[0120] The bottom gate type thin film transistor elements of Examples 1 to 4, in which a protective film was formed using a composition containing a polysiloxane polymer having a SiH group, had an electron mobility of 35 cm 2 / Vs or more, and the electron mobility was significantly improved compared to the element of Reference Example 1, which did not have a protective film. In Examples 1 to 4, there was a tendency that the electron mobility of the element increased as the amount of SiH groups in the protective film increased.

[0121] In Comparative Example 1, in which a protective film was formed using a composition containing no SiH groups, the electron mobility of the device was increased compared to Reference Example 1, but the electron mobility was 20 cm 2 In Comparative Examples 2 and 3, the electron mobility was lower than that in Reference Example 1.

[0122] The top gate type thin film transistor element of Example 6 was also 35 cm 2 The electron mobility was significantly improved compared to the device of Reference Example 2, in which no interlayer insulating film was formed. The device of Comparative Example 6, in which the interlayer insulating film was formed using a composition containing no SiH groups, showed a lower electron mobility than that of Reference Example 2.

[0123] In Example 5, which used the same composition as in Example 1 but changed the heat curing temperature to 200°C, the electron mobility of the device was lower than in Example 1, but was significantly higher than in Reference Example 1. In Comparative Example 4, in which the heat curing temperature was 150°C, and Comparative Example 5, in which the heat curing temperature was 180°C, the electron mobility was higher than in Reference Example 1, but the significant increase in electron mobility as in Examples 1 and 5 was not observed.

[0124] These results demonstrate that the electron mobility of both top-gate and bottom-gate devices can be improved by applying a resin composition containing SiH groups to an oxide semiconductor thin film and then heating it at high temperatures. The improvement in electron mobility was more pronounced with increasing amounts of SiH groups in the resin composition and increasing heating temperatures. [Explanation of symbols]

[0125] 1 board 2. Gate insulating film 31 Gate Layer 4. Oxide semiconductor thin film 6 Resin film 51, 52, 53, 54 Source and drain electrodes 45,46 Channel region 91, 92, 93, 94 Contact holes

Claims

1. A method for manufacturing a thin film transistor element comprising: a gate layer; an oxide semiconductor thin film; a gate insulating film disposed between the gate layer and the oxide semiconductor thin film; a pair of source and drain electrodes electrically connected to the oxide semiconductor thin film; and a resin film covering the oxide semiconductor thin film, the oxide semiconductor thin film contains two or more metal elements selected from the group consisting of indium, gallium, zinc, and tin, a step of applying a composition containing a SiH group-containing compound onto the oxide semiconductor thin film, and then heating the composition at 190 to 450° C. to form the resin film; The method for manufacturing a thin film transistor element, wherein the SiH group-containing compound contains a cyclic polysiloxane structure and 0.1 mmol / g or more of SiH groups.

2. A method for manufacturing a thin film transistor element comprising: a gate layer; an oxide semiconductor thin film; a gate insulating film disposed between the gate layer and the oxide semiconductor thin film; a pair of source and drain electrodes electrically connected to the oxide semiconductor thin film; and a resin film covering the oxide semiconductor thin film, the oxide semiconductor thin film contains two or more metal elements selected from the group consisting of indium, gallium, zinc, and tin, a step of applying a composition containing a SiH group-containing compound onto the oxide semiconductor thin film, and then heating the composition at 190 to 450° C. to form the resin film; the SiH group-containing compound contains 0.1 mmol / g or more of SiH groups, A method for manufacturing a thin film transistor element, wherein the element has an electron mobility of 35 cm 2 / Vs or more.

3. The method for manufacturing a thin film transistor element according to claim 2 , wherein the SiH group-containing compound includes a polysiloxane structure.

4. The method for manufacturing a thin film transistor element according to claim 2 , wherein the SiH group-containing compound includes a cyclic polysiloxane structure.

5. 5. The method for manufacturing a thin film transistor element according to claim 1, wherein the SiH group-containing compound is a polymer.

6. 6. The method for manufacturing a thin film transistor element according to claim 1, wherein the resin film is also formed on the pair of source and drain electrodes.

7. 7. The method for manufacturing a thin film transistor element according to claim 1, further comprising the step of patterning the resin film by photolithography to form contact holes.

8. 8. The method for producing a thin film transistor element according to claim 1, wherein the composition is a negative photosensitive composition.

9. 8. The method for manufacturing a thin film transistor element according to claim 1, wherein the composition is a positive photosensitive composition.

10. 7. The method for producing a thin film transistor element according to claim 1, wherein the composition is a photo- or thermosetting composition or a thermosetting composition that is not alkali-soluble.

11. 11. The method for manufacturing a thin film transistor element according to claim 1, wherein the gate insulating film covers the gate layer, and the oxide semiconductor thin film is provided on the gate insulating film.

12. 11. The method for manufacturing a thin film transistor element according to claim 1, wherein the gate insulating film and the gate layer are provided in this order on the oxide semiconductor thin film.

13. A thin film transistor element comprising: a gate layer; an oxide semiconductor thin film; a gate insulating film disposed between the gate layer and the oxide semiconductor thin film; a pair of source and drain electrodes electrically connected to the oxide semiconductor thin film; and a resin film covering the oxide semiconductor thin film, the oxide semiconductor thin film contains two or more metal elements selected from the group consisting of indium, gallium, zinc, and tin, the resin film is in contact with the oxide semiconductor thin film and contains a SiH group; Electron mobility is 35 cm ２ / Vs or more.

14. The thin film transistor element according to claim 13 , wherein the amount of SiH groups in the resin film is 0.001 mmol / g or more.

15. The thin film transistor element according to claim 13 or 14, wherein the resin film contains a polymer containing a SiH group and a polysiloxane structure.

16. The thin film transistor element according to claim 13 or 14, wherein the resin film contains a polymer containing a SiH group and a cyclic polysiloxane structure.

17. 17. The thin film transistor element according to claim 13, wherein the gate insulating film covers the gate layer, and the oxide semiconductor thin film is provided on the gate insulating film.

18. 17. The thin film transistor element according to claim 13, wherein the gate insulating film and the gate layer are provided in this order on the oxide semiconductor thin film.

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