JP2007043055A - Thin film transistor and gate insulating film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin film transistor with excellent performance of a high mobility and a high ON/OFF current ratio wherein the cost of a gate insulating film is reduced and the manufacturing process are simplified. <P>SOLUTION: In the thin film transistor wherein a gate electrode and the gate insulating film are formed on a substrate, the gate insulating film has a structure represented by the formula (1), and is formed by using: at least one of a silicon-containing polymer (A1) wherein at least one of R<SB>11</SB>to R<SB>1n</SB>is H; and a silicon-containing photosensitive composition which generates an acid or a base when irradiated with an active ray or radiation ray. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a field effect thin film transistor and a gate insulating film of a field effect transistor, and more specifically, an inorganic-organic hybrid material obtained by irradiating a silicon-containing photosensitive composition with light to introduce a crosslinked structure. The present invention relates to a thin film transistor and a gate insulating film in which at least a gate insulating film is formed.

  2. Description of the Related Art Conventionally, field effect thin film transistors have been widely used as switching elements and the like in various electronic devices such as liquid crystal display devices in order to reduce the thickness.

  In a field-effect thin film transistor, a source electrode and a drain electrode are formed so as to be in contact with a semiconductor layer, and a gate electrode is formed so as to be separated from the semiconductor layer via a gate insulating film.

  The gate insulating film has a function of electrically insulating the semiconductor layer and the gate electrode, but is made of an inorganic material such as silicon carbide, silicon nitride, aluminum oxide, tantalum oxide, or titanium oxide. That is, a gate insulating film is formed by depositing these inorganic materials on CVD or the like. However, when an inorganic material is formed by CVD or the like, a vacuum system is required, the manufacturing cost must be high, and a printing method or the like cannot be used, so that the process tends to be complicated. It was.

  On the other hand, various field effect transistors in which the gate insulating film is made of an organic material have been recently proposed. For example, Patent Document 1 and Non-Patent Document 1 listed below show a gate insulating film made of an organic material such as polyimide, polymethyl (meth) acrylate, and polyvinyl alcohol as the gate insulating film.

When the gate insulating film is formed using these organic materials, a coating method or a printing method can be used, and the gate insulating film can be formed without requiring a large vacuum device. Therefore, the manufacturing cost of the gate insulating film can be reduced, and the process can be simplified. On the other hand, in a field effect transistor, a passivation film is often provided to protect the central portion including the semiconductor layer and the like. The passivation film is conventionally formed of an organic material such as polyvinyl alcohol or an inorganic material such as SiN.
JP 2004-349319 A SID05 DiGEST. “3.2: Invited Paper: High-Performance OTFTs on Flexible Substrate”

  As described above, in recent years, in order to increase productivity, it has been attempted to form the gate insulating film with an organic material such as polyvinyl alcohol or polyimide. However, the gate insulating film using these organic materials has a problem that the insulating property is inferior to the gate insulating film made of an inorganic material. That is, when an inorganic material is formed by CVD, the obtained film is dense and excellent in insulation, whereas a gate insulating film obtained by forming an organic material has a dense film structure. Therefore, there is a problem that the insulation is not sufficient. In addition, the insulating property may be impaired due to the presence of ion conductive impurities in the organic material.

If the insulating property of the gate insulating film is not sufficient, the mobility in the field effect transistor is lowered, and the on / off current ratio I _ON / I _OFF is lowered, making it difficult to improve the performance of the transistor. In particular, when used as a switching element, the current flowing between the source and drain electrodes when the transistor is in the on state is I _ON, and the current I _OFF flowing between the source electrode and the drain electrode when the transistor is in the off state It is strongly required that the on / off ratio I _ON / I _OFF which is the ratio of In addition, the passivation film is not only formed inexpensively with an organic material, but also strongly demands that the semiconductor layer and the central portion of the thin film transistor can be reliably protected. When placed below, it has been difficult to sufficiently improve moisture resistance.

  The object of the present invention is to eliminate the above-mentioned disadvantages of the prior art, to form a gate insulating film without requiring an expensive vacuum device, and to increase the mobility and the on / off current ratio. It is an object of the present invention to provide a thin film transistor which can be obtained and a gate insulating film which makes it possible to obtain such a thin film transistor.

A first invention of the present application includes a semiconductor layer, a source electrode and a drain electrode provided so as to be in contact with the semiconductor layer, a gate electrode, and a gate insulating film disposed between the gate electrode and the semiconductor layer. It is a field effect type thin film transistor, wherein the gate insulating film is composed of a thin film formed using a silicon-containing photosensitive composition, and the silicon-containing photosensitive composition is represented by the following general formula (1) And at least one silicon-containing polymer (A1) in which at least one of R _{11 to} R _1n is H, and a compound that generates an acid or a base upon irradiation with actinic rays or radiation (B ).

(In the formula, at least one of R _{11 to} R _1n is H, and n is an integer of 1 or more.)
Here, the “thin film formed using the silicon-containing photosensitive composition” is a thin film obtained by introducing energy such as heat or light to the silicon-containing photosensitive composition and introducing a crosslinked structure. It means that there is.

  In a specific aspect of the thin film transistor according to the present invention, the thin film transistor further includes a passivation film, and the passivation film is formed by a thin film formed using the silicon-containing photosensitive composition.

In another specific aspect of the thin film transistor according to the present invention, the weight average molecular weight of the silicon-containing polymer (A1) is Mw, and the total of substituents R _{11 to} R _{1n in} the silicon-containing polymer (A1) is 100 mol%. In this case, the ratio of the substituent that is H is set within the range surrounded by a broken line A in FIG. 4 described later according to the weight average molecular weight Mw.

In still another specific aspect of the thin film transistor according to the present invention, the silicon-containing photosensitive composition is represented by the following general formula (2), and at least R _{21 to} R _2n are atoms or functional groups other than H. A seed polymer (A2) is further included.

(In the formula, R _{21 to} R _2n are atoms or functional groups other than H, and n is an integer of 1 or more.)
In still another specific aspect of the thin film transistor according to the present invention, the weight-average molecular weight Mw of the silicon-containing polymer (A1) and the silicon-containing polymer (A2) is set, and the ratio of substituents that are H is the silicon-containing polymer (A1). And (A2), the total amount of substituents R _{11 to} R _1n and substituents R _{21 to} R _2n is 100 mol%. It is said that.

  In still another specific aspect of the thin film transistor according to the present invention, the compound (B) is at least one compound selected from the group consisting of an onium salt, a diazonium salt, and a sulfonate ester.

  In still another specific aspect of the thin film transistor according to the present invention, the compound (B) is an amine imide compound that generates a base upon irradiation with actinic rays or radiation.

A second invention of the present application is a gate insulating film of a field effect transistor, which has a structure represented by the general formula (1), and at least one of R _{11 to} R _1n is H. A thin film formed by using a silicon-containing photosensitive composition comprising: a silicon-containing polymer (A1); and a compound (B) that generates an acid or a base upon irradiation with actinic rays or radiation. It is characterized by becoming.

In a specific aspect of the second invention, the silicon-containing photosensitive composition is represented by the general formula (2), and at least one polymer (R _{21 to} R _2n is an atom or a functional group other than H) ( A2) is further included.

  Details of the present invention will be described below.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have used a specific organic-inorganic hybrid material, that is, a gate insulating film made of a crosslinked product of the specific silicon-containing photosensitive composition. It has been found that the mobility of the thin film transistor can be increased and the on / off current ratio can be increased, and the present invention has been made.

  That is, the said silicon-containing photosensitive composition contains the said specific silicon-containing polymer and the compound (B) which generate | occur | produces an acid or a base by radiation | emission of actinic light or a radiation. The silicon-containing polymer includes at least one silicon-containing polymer (A1).

In the following general formula (1), at least one of R _{11 to} R _1n is H, and the rest of the silicon-containing polymer (A1) is an atom or functional group other than H.

Therefore, in the silicon-containing polymer (A1), when all of R _{11 to} R _1n are H, the silicon-containing polymer (A1) is

A polymer having a skeleton consisting of

In the silicon-containing polymer (A1), the substituents R _{11 to} R _1n may be the same or different.

  In the present invention, at least one silicon-containing polymer (A1) is blended, and therefore two or more silicon-containing polymers (A1) may be contained.

As described above, in the silicon-containing polymer (A1), since at least one of the substituents R _{11 to} R _1n is H, the silicon-containing polymer (A1) has a —SiH group. The —SiH group easily reacts with moisture in the air by the action of an acid or base generated from the compound (B) upon irradiation with actinic rays or radiation. As a result, the —SiH group of the silicon-containing polymer (A1) and the —SiH group of the adjacent silicon-containing polymer (A1) easily react with H ₂ O in the air to form Si—O—Si bonds. Crosslinking proceeds and becomes insoluble in the developer. That is, since R ₁ and / or R ₂ has a —SiH group, even if a cross-linking agent is not used, the —SiH group reacts with moisture in the air to promote cross-linking, and an insoluble portion is formed. . Therefore, according to the present invention, the use of a crosslinking agent can be omitted.

In the silicon-containing polymer (A1), R _{11 to} R _1n that are not H are not particularly limited, but are substituted or unsubstituted aliphatic hydrocarbon groups, substituted or unsubstituted alicyclic hydrocarbon groups, substituted or unsubstituted. And an organic group such as a substituted or unsubstituted polar group-containing organic group. More specifically, examples of such an organic group include a methyl group, an n-propyl group, an n-butyl group, an n-hexyl group, a phenylmethyl group, a trifluoropropyl group, and a nonafluorohexyl group. Substituted or unsubstituted aliphatic hydrocarbon groups, cyclohexyl groups, substituted or unsubstituted aromatic hydrocarbon groups such as methylcyclohexyl groups, p-tolyl groups, biphenyl groups, and substituted or unsubstituted groups such as phenyl groups And a substituted or unsubstituted polar group-containing organic group such as a hydroxyl group-containing group, a carboxyl group, and a phenolic hydroxyl group-containing group.

R _{11 to} R _1n may be functional groups or atoms other than organic groups. Examples of such atoms and functional groups include halogens such as fluorine or chlorine, halide groups, hydroxyl groups, alkoxide groups, amino groups, nitro groups, sulfoxide groups, and nitrile groups. About R _{< 11} > -R <_1n> , an organic group or these atoms and functional groups may be mixed.

  Further, in the general formula (1), the structure of the skeleton having a siloxane group is not particularly limited, and may be any of a random type, a ladder type, a cage type, and the like. Further, a plurality of polymers having various structures such as a random type, a ladder type, or a saddle type may be used.

  In the present invention, not only the silicon-containing polymer (A1) but also at least one silicon-containing polymer (A2) represented by the following general formula (2) may be further included.

In the silicon-containing polymer (A2), R _{21 to} R _2n are all atoms or functional groups other than H, and n is an integer of 1 or more. Examples of the atoms and functional groups other than H include the same functional groups as the atoms and organic groups other than H described above in the silicon-containing polymer (A1). In the silicon-containing polymer (A2), R _{21 to} R _2n may be the same or different. Moreover, in this invention, 2 or more types may be contained for the said silicon-containing polymer (A2).

  When the silicon-containing polymer (A1) is produced, the silicon-containing polymer (A2) is usually often generated as a by-product. Therefore, in the present invention, in addition to the silicon-containing polymer (A1), the silicon-containing polymer (A2) is often further included. But silicon-containing polymer (A2) does not necessarily need to be contained.

  When the silicon-containing polymer (A2) is contained in addition to the silicon-containing polymer (A1), the silicon-containing polymer (A2) does not have a —SiH group and is difficult to crosslink without a crosslinking agent. It is better to have less. More specifically, when the silicon-containing polymer (A1) and the silicon-containing polymer (A2) are contained, the blending ratio of the silicon-containing polymer (A2) is 100 parts by weight of the silicon-containing polymer (A1). The amount is desirably 400 parts by weight or less.

In the present invention, when the silicon-containing polymer (A2) is contained in addition to the silicon-containing polymer (A1), the substituents R _{11 to} R _1n and the substituents R _{21 to} R are preferable. the proportion of substituent is H in _2n is the sum of the substituents R ₁₁ to R _1n and substituents _{R 21} to R _2n is 100 mole%, a mixture of silicon-containing polymer (A1) and the silicon-containing polymer (A2) When the weight average molecular weight Mw is, it is within the range surrounded by the broken line A in FIG. Outside this range, crosslinking due to the generation of Si—O—Si bonds may not proceed easily.

  In any case, in the range surrounded by the broken line A in FIG. 4, according to the present invention, Si—O—Si bonds are rapidly formed and crosslinking proceeds.

  The weight average molecular weight of the above mixture is, for example, 100% fraction of the silicon-containing polymer (A1) as x (%), and the weight content of the silicon-containing polymer (A2) as Y (%). When the weight average molecular weight MA1 of A1) and the weight average molecular weight MA2 of the silicon-containing polymer (A2) are represented, (x · MA1 + Y · MA2) / 100.

The compound (B) used in the present invention is a compound that generates an acid or a base upon irradiation with actinic rays or radiation. Such a compound is not particularly limited, and examples of the compound that generates an acid include onium salts. More specifically, salts of diazonium, phosphonium, and iodonium such as BF ₄ ⁻ , PF ₆ ⁻ , SBF ₆ ⁻ , and ClO ₄ ^— , and other organic halogen compounds, organic metals, and organic halides can be used. . More specifically, the acid generating compound includes triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium trifluoromethaneantimonate, triphenylsulfonium benzosulfonate, cyclohexylmethyl (2-oxocyclohexyl) sulfonium trifluoromethanesulfonate. Sulfonium salt compounds such as dicyclohexyl (2-oxocyclohexyl) sulfonium trifluoromethanesulfonate, dicyclohexylsulfonylcyclohexanone, dimethyl (2-oxocyclohexyl) sulfonium trifluoromethanesulfonate, iodonium salts such as diphenyliodonium trifluoromethanesulfonate, N-hydroxy Succinimide trifluoromethanesulfonate, etc. Including but not limited to.

  Only 1 type may be used for the compound (B) which generate | occur | produces the acid by irradiation of the said actinic light or a radiation, and 2 or more types may be used together.

  The compound that generates an acid upon irradiation with actinic rays or radiation is not particularly limited, but preferably, at least one compound selected from the group consisting of a more reactive onium salt, diazonium salt, and sulfonate ester is used. Used.

  The content ratio of the compound that generates the acid is 0.05 to 50 weights with respect to 100 parts by weight of the resin component that is the total of the silicon-containing polymer (A1) and the silicon-containing polymer (A2) added as necessary. It is desirable to be in the range of parts. That is, it is desirable to set it as the ratio of 0.5-30 weight part with respect to 100 weight part of resin parts. If it is less than 0.05 parts by weight, the sensitivity may not be sufficient, and it may be difficult to form a thin film pattern. If it exceeds 50 parts by weight, it is difficult to uniformly apply the photosensitive composition. Residues may easily occur after development.

  In addition to these photosensitizers, a sensitizer may be further added to increase sensitivity. Specific examples of suitable sensitizers include benzophenone, p, p′-tetramethyldiaminobenzophenone, p, p′-tetraethylaminobenzophenone, 2-chlorothioxanthone, anthrone, 9-ethoxyanthracene, anthracene, pyrene, Perylene, phenothiazine, benzyl, acridine orange, benzoflavin, cetoflavin-T, 9,10-diphenylanthracene, 9-fluorenone, acetophenone, phenanthrene, 2-nitrofluorene, 5-nitroacenaphthene, benzoquinone, 2-chloro-4- Nitroaniline, N-acetyl-p-nitroaniline, p-nitroaniline, N-acetyl-4-nitro-1-naphthylamine, picramide, anthraquinone, 2-ethylanthraquinone, 2-tert-butylant Laquinone, 1,2-benzanthraquinone, 3-methyl-1,3-diaza-1,9-benzanthrone, dibenzalacetone, 1,2-naphthoquinone, 3,3′-carbonyl-bis (5,7 -Dimethoxycarbonylcoumarin) and coronene, but are not limited thereto.

  In the present invention, a compound that generates a base upon irradiation with actinic rays or radiation may be used as the compound (B). Examples of the compound that generates such a base include cobalt amine complexes, o-acyl oximes, carbamic acid derivatives, formamide derivatives, quaternary ammonium salts, tosyl amines, carbamates, amine imide compounds, and the like. Specifically, 2-nitrobenzylcarbamate, 2,5-dinitrobenzylcyclohexylcarbamate, N-cyclohexyl-4-methylphenylsulfonamide, 1,1-dimethyl-2-phenylethyl-N-isopropylcarbamate and the like are preferable. Can be used.

  As the compound (B) that generates a base, an amine imide compound that generates a base by irradiation with actinic rays or radiation is preferably used. Such an amine imide compound is not particularly limited as long as it generates a base when irradiated with actinic rays or radiation. Examples of such amine imide compounds include compounds represented by the following general formula (3) or (4).

In the general formulas (3) and (4), R ¹ , R ² and R ³ are independently hydrogen, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, and an alkyl group having 1 to 8 carbon atoms. An alkylidene group, a cycloalkyl group having 4 to 8 carbon atoms, a cycloalkenyl group having 4 to 8 carbon atoms, a phenoxyalkyl group having 1 to 6 carbon atoms, a phenyl group, an electron donating group and / or an electron withdrawing group substituted. Examples thereof include a benzyl group substituted with a phenyl group, a benzyl group, an electron donating group and / or an electron withdrawing group. As a C1-C8 alkyl group, the alkyl group which has a substituent other than a linear alkyl group, for example, an isopropyl group, an isobutyl group, t-butyl group etc. are included. Among these substituents, from the viewpoint of ease of synthesis, solubility of amine imide, etc., an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 6 to 8 carbon atoms, and a phenoxyalkyl group having 1 to 6 carbon atoms. Is preferred. R ⁴ independently represents an alkyl group having 1 to 5 carbon atoms, a hydroxyl group, a cycloalkyl group having 4 to 8 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a phenyl group. Ar ¹ in the general formula (3) is an aromatic group, and such an amine imide compound is known prior to the filing of the present application as disclosed in, for example, Japanese Patent Application Laid-Open No. 2003-35949. Are available. Ar ² in the general formula (4) is an aromatic group.

  The amine imide compound has higher base generation efficiency than a compound that generates a primary or secondary amine when irradiated with actinic rays or radiation. Therefore, it is possible to shorten the exposure time and hence the manufacturing process, which is desirable.

  As for the said compound (B) which generate | occur | produces the base, only 1 type may be used and 2 or more types may be used together. In addition, it is desirable that the content ratio of the compound (B) that generates a base is usually in the range of 0.05 to 50 parts by weight with respect to 100 parts by weight of the resin. If it is less than 0.05 part by weight, the sensitivity may be lowered, and it may be difficult to form a thin film pattern. When the amount exceeds 50 parts by weight, it is difficult to uniformly apply the photosensitive composition, and a residue may be easily generated after the phenomenon.

  In addition, in order to obtain an optimal resist shape, you may use a photoacid generator and a photobase generator in combination of 2 or more types, respectively.

  In the present invention, an appropriate solvent may be added in addition to the silicon-containing polymer (A1), the optionally added silicon-containing polymer (A2), and the compound (B). By adding a solvent, a photosensitive composition that can be easily applied can be easily provided. The solvent to be used is not particularly limited as long as it can dissolve the silicon-containing polymer (A1). However, aromatic hydrocarbon compounds such as benzene, xylene, toluene, ethylbenzene, styrene, trimethylbenzene, and diethylbenzene; cyclohexane, cyclohexene, Saturated or unsaturated hydrocarbons such as dipentene, n-pentane, isopentane, n-hexane, isohexane, n-heptane, isoheptane, n-octane, isooctane, n-nonane, isononane, n-decane, isodecane, tetrahydronaphthalene, squalane Compound: diethyl ether, di-n-propyl ether, di-isopropyl ether, dibutyl ether, ethyl propyl ether, diphenyl ether, diethylene glycol dimethyl ether, diethyl Glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol methyl ethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, dipropylene glycol dibutyl ether, dipropylene glycol methyl ethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol di Propyl ether, ethylene glycol methyl ethyl ether, tetrahydrofuran, 1,4-dioxane, propylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, dipropylene glycol methyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl Cyclohexane, methylcyclohexane, p-menthane, o-menthane, m-menthane; ethers such as dipropyl ether, dibutyl ether; acetone, methyl ethyl ketone, methyl isobutyl ketone, diethyl ketone, dipropyl ketone, methyl amyl ketone, cyclopentanone Ketones such as cyclohexanone and cycloheptanone; ethyl acetate, methyl acetate, butyl acetate, propyl acetate, cyclohexyl acetate, methyl cellosolve, ethyl cellosolve, butyl cellosolve, ethyl lactate, propyl lactate, butyl lactate, isoamyl lactate, stearin And esters such as butyl acid. These solvents can be used alone or in combination of two or more.

  The usage ratio of the solvent in the silicon-containing photosensitive composition used in the thin film transistor according to the present invention is such that it is uniformly applied when the photosensitive composition is applied to form the photosensitive composition layer. May be selected as appropriate. Preferably, the concentration of the photosensitive composition is 0.5 to 60% by weight, more preferably about 2 to 40% by weight in terms of solid content.

  You may add another additive to the said photosensitive composition further as needed. Such additives include fillers, pigments, dyes, leveling agents, antifoaming agents, antistatic agents, UV absorbers, pH adjusters, dispersants, dispersion aids, surface modifiers, plasticizers, plasticizers. Examples include accelerators and sagging inhibitors.

  Next, a method for forming a thin film pattern for forming a gate insulating film or a passivation film using the above-mentioned silicon-containing photosensitive composition will be described. For example, as shown in FIG. 1A, the thin film pattern is formed by a step of forming a photosensitive composition layer 1 made of the photosensitive composition according to the present invention, and then a photosensitive composition layer 1. Are selectively exposed using a photomask 3 corresponding to the pattern to form a patterned latent image 1A (FIG. 1B), and the photosensitive layer 1B on which the latent image is formed is washed with an alkaline aqueous solution. And a developing step (FIG. 1C). Here, development means an operation of immersing the photosensitive layer 1B on which a latent image is formed in an alkaline aqueous solution, an operation of washing the surface of the photosensitive layer 1B with an alkaline aqueous solution, or an alkaline aqueous solution on the surface of the photosensitive layer 1B. It includes various operations for treating the photosensitive layer 1B with an alkaline aqueous solution, such as a spraying operation.

  The developing solution is not limited to an alkaline aqueous solution, and an acidic aqueous solution or various solvents may be used. Examples of the solvent include the various solvents described above. Examples of the acidic aqueous solution include oxalic acid, formic acid, acetic acid and the like.

  Although the process of forming the said photosensitive composition layer is not specifically limited, For example, the method of providing the photosensitive composition which concerns on this invention on the board | substrate 2 shown in FIG. 1, and forming the photosensitive composition layer 1 is mentioned. It is done. As a specific method in this case, a general coating method can be used, for example, dip coating, roll coating, bar coating, brush coating, spray coating, spin coating, extrusion coating. Work, gravure coating, etc. can be used. As a substrate to which the photosensitive composition is applied, a silicon substrate, a glass substrate, a metal plate, a plastics plate, or the like is used depending on the application. The thickness of the photosensitive composition layer varies depending on the use, but 10 nm to 10 μm is a standard. When the photosensitive composition layer coated on the substrate uses a solvent to dissolve the photosensitive resin, it is desirable to heat-treat the solvent to dry the solvent. The heat treatment temperature is generally 40 ° C. to 200 ° C., and is appropriately selected according to the boiling point and vapor pressure of the solvent.

  A photosensitive composition layer is formed on a substrate, heat-treated as necessary, and then the photosensitive composition layer is covered with a photomask and irradiated with light in a pattern. Thereby, a latent image having a necessary pattern shape can be formed. What is necessary is just to use the common thing marketed as a photomask.

As the light source, an ultrahigh pressure mercury lamp, a deep UV lamp, a high pressure mercury lamp, a low pressure mercury lamp, a metal halide lamp, an excimer laser, or the like can be used. These light sources are appropriately selected according to the photosensitive wavelength of the photoacid generator, photobase generator and sensitizer. The light irradiation energy is generally 10 to 1000 mJ / cm ² , although it depends on the desired thickness of the thin film and the type of photoacid generator, photobase generator and sensitizer. When it is less than 10 mJ / cm ² , the silicon-containing polymer is not sufficiently exposed. On the other hand, if it is larger than 1000 mJ / cm ² , the exposure time may be prolonged, and the production efficiency per time of the thin film pattern may be lowered.

  In the exposed portion of the photosensitive composition layer irradiated with light in the pattern shape, as described above, the —SiH group of the silicon-containing polymer (A1) is exposed in the air by the action of the acid or base generated from the compound (B) upon exposure. Reacts with moisture and reacts with -SiH groups of adjacent polymers. As a result, Si—O—Si bonds are generated and crosslinking proceeds, resulting in insolubility in the developer. Therefore, as a result of the progress of crosslinking in the exposed portion, it becomes insoluble in the alkaline developer. By developing the photosensitive composition layer after exposure using a developer, the unexposed portion of the photosensitive composition layer is dissolved and removed in the developer, and the exposed portion remains on the substrate. As a result, a pattern is formed. This pattern is called a negative pattern because unexposed portions are removed.

  As the developer, an explosion-proof facility is unnecessary, and the burden on the facility due to corrosion or the like is small, so an alkaline aqueous solution is preferably used. For example, alkaline aqueous solutions, such as tetramethylammonium hydroxide aqueous solution, sodium silicate aqueous solution, sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, are mentioned. The time required for development depends on the thickness of the photosensitive composition layer and the type of solvent, but is generally 10 seconds to 5 minutes. The thin film pattern used after development is preferably washed with distilled water to remove the aqueous alkali solution remaining on the thin film.

  In the thin film transistor according to the present invention, the gate insulating film is formed by the thin film pattern formed as described above. In this case, as described above, a large-scale vacuum apparatus is not required for forming the gate insulating film. Therefore, the gate insulating film can be formed inexpensively and efficiently.

  In addition, since the gate insulating film is formed of the crosslinked film of the above-mentioned silicon-containing photosensitive composition, as can be seen from the experimental examples described later, the mobility can be increased and the on / off current value can be increased. it can.

  In the thin film transistor according to the present invention, preferably, a passivation film is further provided, and this passivation film is also a thin film formed using the above-mentioned silicon-containing photosensitive composition. Even in this case, the protection performance under high temperature and high humidity can be improved as compared with the case where a passivation film made of a conventional PVA film is used.

  In the thin film transistor according to the present invention, as described above, the gate insulating film is constituted by the crosslinked film of the specific silicon-containing photosensitive composition, and therefore other structures are not particularly limited. That is, a field effect thin film transistor including a semiconductor layer, a source electrode, a drain electrode, and a gate electrode provided in contact with the semiconductor layer, and the gate insulating film disposed between the gate electrode and the semiconductor layer. As long as there is a physical structure, it is not particularly limited. Specific examples of the structure of such a field effect thin film transistor are illustrated in FIGS.

  In the thin film transistor 11 shown in FIG. 2, the gate electrode 13 is formed on the substrate 12. A gate insulating film 14 is formed so as to cover the gate electrode 13. The gate insulating film 14 is constituted by a crosslinked film of the specific silicon-containing photosensitive composition. A semiconductor layer 15 is stacked on the gate insulating film 14. A source electrode 16 and a drain 17 electrode are formed in contact with the semiconductor layer 15. Further, a passivation film 18 is formed so as to cover the semiconductor layer 15, the source electrode 16 and the drain electrode 17. An ITO electrode 19 connected to the drain electrode 17 is formed thereon.

  On the other hand, in the thin film transistor 21 shown in FIG. 3, the semiconductor layer 23 is formed on the substrate 22. A gate insulating film 24 is formed on the semiconductor layer 23. The gate insulating film 24 is formed of a crosslinked film of the silicon-containing photosensitive composition. A gate electrode 25 is formed on the gate insulating film 24. On the other hand, the source electrode 26 and the drain electrode 27 penetrate the gate insulating film 24 and are joined to the semiconductor layer 23.

  A passivation film 28 is formed on the gate insulating film 24 and the gate electrode 25. Further, a passivation film 29 is laminated to flatten the upper surface, and an ITO electrode 30 connected to the drain electrode 27 is formed on the passivation film 29.

  As shown in the thin film transistors 11 and 21, the structure of the thin film transistor to which the present invention is applied is not particularly limited. Further, there is no particular limitation on the material forming the semiconductor layer in the thin film transistor according to the present invention, and various semiconductors such as amorphous silicon, polysilicon, and organic semiconductor can be used. The source electrode, the drain electrode, and the gate electrode can also be made of an electrode material made of an appropriate metal.

  In addition, the passivation films 18, 28, and 29 are not essential, but are preferably formed of a crosslinked film of the silicon-containing photosensitive composition. However, the passivation films 18, 28, and 29 may be made of an inorganic material such as SiN or may be made of an organic material such as PVA. Further, the passivation films 18, 28, and 29 may be configured using a combination of a crosslinked film of the silicon-containing photosensitive composition and an inorganic material such as SiN or an organic material such as PVA.

  In the thin film transistor according to the present invention, the gate insulating film is a thin film formed using the specific silicon-containing photosensitive composition. This thin film is an organic-inorganic hybrid material, and like a thin film made of an organic material, it can be easily formed without requiring a large vacuum device, and has a dense film structure. Therefore, not only can the gate insulating film be formed at low cost, but also the mobility and on / off current ratio in the obtained thin film transistor can be increased. Accordingly, a high-performance thin film transistor can be provided at a low cost.

  In the present invention, when the passivation film is made of a crosslinked film of the above-mentioned silicon-containing photosensitive composition, the moisture resistance of the passivation film is enhanced, and it is possible to suppress deterioration of performance under high temperature and high humidity.

  Since the gate insulating film according to the present invention is composed of a thin film formed using the above-mentioned silicon-containing photosensitive composition, it is possible to provide a thin film transistor that can be formed at low cost and has excellent performance according to the present invention. It becomes possible.

  Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention. The present invention is not limited to the following examples.

[Experimental Example 1]
The thin film transistor 11 shown in FIG. 1 was produced. On the silicon substrate, the gate electrode 13 made of N-type doped silicon was formed. After that, the gate insulating film and below were fabricated in the following manner.

Example 1
(Preparation of polymer)
To a 100 ml flask equipped with a condenser, 5 g of phenyltriethoxysilane, 10 g of triethoxysilane, 0.5 g of oxalic acid, 5 ml of water, and 50 ml of propylene glycol monomethyl ether acetate were added to obtain a solution. The solution was stirred using a semicircular type mechanical stirrer and reacted at 70 ° C. for 6 hours with a mantle heater. Next, water and ethanol produced by the condensation reaction were removed using an evaporator. After completion of the reaction, the flask was left to reach room temperature to prepare a silicon-containing polymer mixture.

  5 parts of 100 parts by weight of the above silicon-containing polymer mixture and a sulfonium salt photoacid generator (Naphtalide camphorsulfate (CAS No. 83697-56-7) as a compound (B), trade name: NAI-106) Part by weight was dissolved in 1000 parts by weight of tetrahydrofuran as a solvent to prepare a photosensitive composition.

For the gate insulating film, this photosensitive composition was spin-coated at a rotation speed of 1500 rpm. After coating, it was dried in a hot air oven at 80 ° C. to form a coating film having a thickness of 200 nm. Next, the coating film was irradiated with ultraviolet rays having a wavelength of 365 nm for 3 seconds at an ultraviolet illuminance of 100 mW / cm ² so that the irradiation energy was 300 mJ / cm ² through a photomask having a predetermined pattern. After irradiation, the coating film was heated in a hot air oven at 80 ° C. for 2 minutes. Thereafter, development was performed with a 2.38% aqueous solution of tetramethylammonium hydroxide, patterning was performed, and heating was performed at 150 ° C. for 1 hour to obtain a gate insulating film.

After producing the gate insulating film, a source electrode and a drain electrode made of Au were formed by vapor deposition. Next, an organic semiconductor layer made of pentacene was formed. In forming the organic semiconductor layer, pentacene was sublimated and deposited on the gate insulating film under an output of 1 × 10 ⁻⁵ torr to form a semiconductor layer having a thickness of 100 nm.

  Thus, the thin film transistor of Example 1 having a channel length of 100 μm and a channel width of 10 μm was produced.

(Comparative Example 1)
A thin film transistor was obtained in the same manner as in Example 1 except that a SiO ₂ film having a thickness of 200 nm was formed by thermal oxidation as the gate insulating film.

(Comparative Example 2)
A thin film transistor was obtained in the same manner as in Example 1 except that the gate insulating film was formed by forming a PVA film as follows.

  The PVA film is formed by applying a polyvinyl alcohol solution (polyvinyl alcohol (N-300 manufactured by Nippon Synthetic Chemical Co., Ltd., 2% by weight solution) on a silicon substrate by a spin coating method (solvent: water: methanol = 4: 1)). 2000 rpm) and cured by heating at 110 ° C. to form a 200 nm thick polyvinyl alcohol film as a gate insulating film.

(Comparative Example 3)
A passivation film of 500 nm was formed on the uppermost portion of the thin film transistor obtained in Comparative Example 1 by depositing and heating the same 4% by weight solution of polyvinyl alcohol as in Comparative Example 2 by spin coating (2000 rpm).

(Example 2)
After forming the source electrode and the drain electrode in Example 1, the amount of tetrahydrofuran as a solvent is 500 parts by weight in the same manner as in the step of forming the gate insulating film in Example 1, and the spin coating is performed. A passivation film having a thickness of 500 nm was formed by setting the number of rotations to 1000 rpm and performing the other steps in the same manner. In this way, a thin film transistor having a passivation film laminated thereon was obtained.

(Example 3)
A passivation film of 500 nm was formed on the top of the thin film transistor obtained in Example 1 by depositing and heating the same 4 wt% solution of polyvinyl alcohol as in Comparative Example 2 by spin coating (2000 rpm).

Example 4
A thin film transistor was obtained in the same manner as in Example 2 except that the gate insulating film was formed to have a thickness of 200 nm by thermal oxidation of SiO ₂ .

(Evaluation)
1. Initial characteristics As initial characteristics, an on / off current ratio I _ON / I _OFF and mobility μ were measured. The results are shown in Table 1 below.

2. High temperature acceleration test A 15 V DC voltage was applied between the gate electrode and the source electrode at a temperature of 80 ° C for 240 hours to perform a high temperature acceleration test. The on / off current ratio and mobility after this high temperature acceleration test were evaluated in Examples 2 and 3.

  The results are shown in Table 1 below.

As is apparent from Table 1, in Comparative Example 1, the gate insulating film was formed of a dense SiO ₂ film, and thus the on / off current ratio was as high as 10 ⁶ and the mobility was as high as 0.82. On the other hand, in Comparative Example 2, since the gate insulating film was made of a PVA film, the on / off current ratio was as low as 10 ⁵ and the mobility was as low as 0.65 (cm ² / Vs).

On the other hand, in Examples 1 to 3, since the insulating film is made of a crosslinked film of the above-mentioned silicon-containing photosensitive composition in the initial state, the on / off current ratio is as high as 10 ⁶ and the mobility is also compared. It turns out that it is equivalent to Example 1.

On the other hand, in Comparative Example 1, since the gate insulating film was formed by CVD of SiO ₂ as described above, an expensive vacuum device was required, and it took a long time to manufacture the gate insulating film, and Cost was high. On the other hand, in Examples 1 to 3, as described above, the gate insulating film could be easily formed simply by coating the silicon-containing photosensitive solution and irradiating light. The manufacturing cost can be reduced and the process can be simplified.

Further, as is clear from the comparison between Example 2 and Example 3 and the comparison between Example 4 and Comparative Example 2, when the passivation film is composed of the silicon-containing photosensitive composition of the present invention, the high temperature It can be seen that even after the energization promotion test, the on / off current ratio is as high as 10 ⁶ and the mobility μ is equal to that in the initial state.

[Experimental example 2]
As shown in Table 2 below, the monomers and materials used were changed, and the others were the same as in Example 1, and various silicon-containing polymers Aa to A-aa were the same as the silicon-containing polymer of Example 1. It was made. Table 2 shows the concentration (% by weight) of the monomer component in a solution composed of the monomer component, oxalic acid or formic acid, water, and propylene glycol monoethyl ether acetate as a solvent, and polymerization as a polymerization condition. The temperature and polymerization time are also shown. Furthermore, Table 2 shows the weight average molecular weight Mw of the obtained silicon-containing polymer and the ratio of the substituent H in each silicon-containing polymer.

  A silicon-containing photosensitive composition was prepared in the same manner as in Example 1 using any of the silicon-containing polymers Af to A-aa obtained as described above.

  A coating film was formed on the wafer in the same manner as in Example 1 using each of the silicon-containing photosensitive compositions prepared as described above. Thereafter, in the same manner as in Example 1, the coating film was immersed in a 2.38 wt% aqueous solution of tetramethylammonium hydroxide for 2 minutes, and the remaining property of the coating film was evaluated. Furthermore, in each silicon-containing photosensitive composition, after forming a coating film in the same manner as described above, one week later, the coating film was immersed in a 2.38 wt% aqueous solution of tetramethylammonium hydroxide for 2 minutes, Survival was evaluated.

  The results are shown in FIG.

  In addition, the horizontal axis | shaft of FIG. 4 shows the weight average molecular weight Mw of the said silicon containing polymer. When two or more types of silicon-containing polymers are used, the weight average molecular weight of the mixture of two or more types of silicon-containing polymers corresponds to Mw in FIG.

  The vertical axis shows the ratio (mol%) of the substituent that is H in the substituent, and the vertical axis is shown as a logarithmic graph. In FIG. 4, the case where the ratio of H is 0 is schematically shown below the portion where the ratio of H is 0.1 mol%.

  In FIG. 4, ◎ indicates that the film was dissolved in the part not irradiated with ultraviolet rays immediately after forming the coating film and after 1 week, and the pattern derived from the photomask was accurately formed. Show. That is, the developability was good. On the other hand, Δ indicates that the developability was good immediately after the coating film was formed, but the developability was not good when developed after one week.

  On the other hand, X in FIG. 4 indicates that the development was not performed well immediately after the formation of the coating film and after one week, for example, the coating film was peeled off or the coating film was exposed even in the portion irradiated with ultraviolet rays. It is dissolved.

  As is clear from FIG. 4, if it is within the range surrounded by the broken line A, the developability is good both immediately after the formation of the coating film and after one week has elapsed, and the coating film is peeled off from the silicon wafer. It turns out that it is hard to occur.

(A)-(c) is sectional drawing of each process for demonstrating the thin film pattern formation method which concerns on this invention. FIG. 2 is a schematic front cross-sectional view showing a structural example of a thin film transistor of the present invention. The typical front sectional view showing other examples of the structure of the thin-film transistor of the present invention. The figure which shows the relationship between the weight average molecular weight of a silicon containing polymer, and the ratio (mol%) of the substituent which is H in a substituent.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Photosensitive composition layer 1A ... Latent image 1B ... Photosensitive layer 1C ... Thin film pattern 2 ... Substrate 3 ... Photomask 11 ... Thin film transistor 12 ... Substrate 13 ... Gate electrode 14 ... Gate insulating film 15 ... Semiconductor layer 16, 17 ... Source Or drain electrode 18 ... passivation film 19 ... ITO electrode 21 ... thin film transistor 22 ... substrate 23 ... semiconductor layer 24 ... gate insulating film 25 ... gate electrode 26, 27 ... source or drain electrode 28, 29 ... passivation film 30 ... ITO electrode

Claims (9)

A field-effect thin film transistor comprising a semiconductor layer, a source electrode and a drain electrode provided in contact with the semiconductor layer, a gate electrode, and a gate insulating film disposed between the gate electrode and the semiconductor layer. The gate insulating film is composed of a thin film formed using a silicon-containing photosensitive composition, and the silicon-containing photosensitive composition has a structure represented by the following general formula (1): At least one silicon-containing polymer (A1) in which at least one of R _{11 to} R _1n is H;
A thin film transistor comprising: a compound (B) that generates an acid or a base upon irradiation with an actinic ray or radiation.

(In the formula, at least one of R _{11 to} R _1n is H, and n is an integer of 1 or more.)   The thin film transistor according to claim 1, further comprising a passivation film, wherein the passivation film is formed of a thin film formed using the silicon-containing photosensitive composition. When the weight average molecular weight of the silicon-containing polymer (A1) is Mw and the total of substituents R _{11 to} R _{1n in} the silicon-containing polymer (A1) is 100 mol%, the ratio of the substituents that are H is weight 3. The thin film transistor according to claim 1, wherein the thin film transistor is in a range surrounded by a broken line A in FIG. 4 described later according to the average molecular weight Mw. The silicon-containing photosensitive composition is represented by the following general formula (2), and further includes at least one polymer (A2) in which R _{21 to} R _2n are atoms or functional groups other than H. The thin-film transistor of any one of Claims 1-3.

(In the formula, R _{21 to} R _2n are atoms or functional groups other than H, and n is an integer of 1 or more.) The weight-average molecular weight Mw of the silicon-containing polymer (A1) and the silicon-containing polymer (A2) is set, and the ratio of substituents that are H is the substituents R _{11 to} R _1n and substitution in the silicon-containing polymers (A1) and (A2). The thin film transistor according to claim 4, wherein the total amount of the groups R _{21 to} R _2n is 100 mol%, and is in a range surrounded by a broken line A in FIG. 4 according to the weight average molecular weight Mw.   The thin film transistor according to claim 1, wherein the compound (B) is at least one compound selected from the group consisting of an onium salt, a diazonium salt, and a sulfonic acid ester.   The thin-film transistor of any one of Claims 1-5 whose said compound (B) is an amine imide compound which generate | occur | produces a base by irradiation of actinic light or a radiation. A gate insulating film of a field effect transistor, which has a structure represented by the following general formula (1), and at least one silicon-containing polymer (A1) in which at least one of R _{11 to} R _1n is H When,
A gate characterized by comprising a thin film formed using a silicon-containing photosensitive composition, comprising a compound (B) that generates an acid or a base upon irradiation with actinic rays or radiation Insulating film.

(In the formula, at least one of R _{11 to} R _1n is H, and n is an integer of 1 or more.) The silicon-containing photosensitive composition is represented by the following general formula (2), and further includes at least one polymer (A2) in which R _{21 to} R _2n are atoms or functional groups other than H. The gate insulating film according to claim 8.

(In the formula, R _{21 to} R _2n are atoms or functional groups other than H, and n is an integer of 1 or more.)

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