JP2004146502A - Organic thin film transistor and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic thin film transistor that is high in mobility and can be manufactured stably, and to provide a method of manufacturing the transistor and a thin film transistor sheet on which thin film transistors are arranged two-dimensionally and which is reduced in cost by reducing the patterning step performed on the sheet and making substantial patterning possible by a simple method. <P>SOLUTION: An organic thin film transistor element is manufactured by heat-melting an organic semiconductor material and by melting a desired portion by projecting light upon the portion by providing a photothermal conversion layer and an organic semiconductor material layer. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an organic thin film transistor device, and more particularly, to an organic thin film transistor device that can be stably manufactured and has excellent operability and a method of manufacturing the same.
[0002]
[Prior art]
In recent years, research and development of organic thin film transistors (hereinafter, referred to as TFTs) that can be manufactured at low cost by low-temperature processes and printing and coating under atmospheric pressure have been conducted. This uses an organic material as an active semiconductor layer in a TFT. This organic material is easy to process and generally has a high affinity for a resin substrate on which a TFT is formed, and is expected to be used as an active semiconductor layer in a thin film device.
[0003]
For example, a TFT using a cast film of a poly (3-alkylthiophene) solution uses an organic semiconductor material that can be subjected to a wet process (for example, see Patent Document 1).
[0004]
[Patent Document 1]
JP-A-10-190001
[0005]
[Problems to be solved by the invention]
However, in the method described in Patent Document 1, the mobility is low, and the mobility varies depending on the casting conditions, so that stable production is difficult.
[0006]
In the case of manufacturing a TFT sheet in which TFTs are two-dimensionally arranged, an active layer is provided for each TFT element in order to input a signal independent from a source bus line to a TFT on the same gate bus line. It must be patterned to be independent. This patterning of the active layer greatly increases the number of steps in the manufacturing process, and is an obstacle to cost reduction.
[0007]
In view of the above problems, the present invention provides a TFT having a high mobility and capable of being manufactured stably and a method for manufacturing the same, and a simple method that reduces a patterning step in a TFT sheet in which TFTs are two-dimensionally arranged. An object of the present invention is to provide a low-cost TFT sheet that enables substantial patterning.
[0008]
[Means for Solving the Problems]
The purpose of the above is
1) a method of manufacturing an organic thin film transistor element, wherein an organic semiconductor layer is formed through a step of heating and melting an organic semiconductor material;
2) An organic material comprising a support, a gate electrode, a gate insulating layer, a source electrode, a drain electrode, and an organic semiconductor material, wherein the organic semiconductor material is heated and melted to form an organic semiconductor layer. Thin film transistor element,
Thus, an organic thin-film transistor element having high mobility, small variation, and stable production can be obtained.
[0009]
Further, when the above-mentioned TFT is one unit and the TFTs are regularly arranged on a sheet,
3) An organic material in which a gate electrode, a gate insulating layer, a source electrode, a drain electrode, and an organic semiconductor material are provided over a sheet-like support, and the organic semiconductor material is heated and melted to form an organic semiconductor layer. An organic thin film transistor sheet, wherein a plurality of thin film transistor elements are arranged,
By doing so, the patterning step in the TFT sheet can be reduced, substantial patterning can be performed by a simple method, and a low-cost TFT sheet can be obtained.
[0010]
Also,
4) The organic semiconductor material is a π-conjugated polymer or oligomer in which an alkyl group possesses an array structure;
5) After being heated and melted, it is cooled, and its cooling rate is 1 ° C./sec or less;
6) The step of heating and melting is performed by providing a light-to-heat conversion layer and irradiating light.
7) Light irradiation is performed by laser,
8) having an alignment film adjacent to the organic semiconductor layer;
Thereby, the effect of the present invention can be further improved.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to embodiments, but the present invention is not limited thereto.
[0012]
The organic semiconductor material according to the present invention will be described.
In the present invention, as the organic semiconductor material, known π-conjugated polymers or oligomers described below are preferably used.
[0013]
(Π-conjugated polymer)
Examples of the π-conjugated polymer include polypyrroles such as polypyrrole, poly (N-substituted pyrrole), poly (3-substituted pyrrole), poly (3,4-disubstituted pyrrole), polythiophene, and poly (3-substituted thiophene). ), Poly (3,4-disubstituted thiophene), polythiophenes such as polybenzothiophene, polyisothianaphthenes such as polyisothianaphthene, polychenylenevinylenes such as polyphenylenevinylene, poly (p-phenylene) Poly (p-phenylenevinylene) s such as vinylene), polyanilines such as polyaniline, poly (N-substituted aniline), poly (3-substituted aniline), poly (2,3-substituted aniline), and polyacetylenes such as polyacetylene , Polydiacetylenes and other polydiacetylenes, polyazulene and other polyarenes Polyenes such as lenes and polypyrene; polycarbazoles such as polycarbazole and poly (N-substituted carbazole); polyselenophenes such as polyselenophene; polyfurans such as polyfuran and polybenzofuran; poly (p-phenylene) Poly (p-phenylene) s, polyindoles such as polyindole, polypyridazines such as polypyridazine, naphthacene, pentacene, hexacene, heptacene, dibenzopentacene, tetrabenzopentacene, pyrene, dibenzopyrene, chrysene, perylene, Polyacenes such as coronene, terylene, ovalene, quaterylene, circum anthracene, and derivatives in which a part of the carbon of polyacenes is substituted with an atom such as N, S, O, or a functional group such as a carbonyl group (triphenodioxazine , Triphenodithiazine, hexacene-6,15-quinone), polyvinyl carbazole, polyphenylene sulfide, polyvinylene sulfide, and other polycyclic condensates described in JP-A-11-195790. .
[0014]
(Π-conjugated oligomer)
In the present invention, for example, α-sexithiophene α, ω-dihexyl-α-sexithiophene, α, ω-dihexyl-α-quinkethiophene, which is a thiophene hexamer having the same repeating unit as the polymer described above, α, ω Oligomers such as -bis (3-butoxypropyl) -α-sexithiophene and styrylbenzene derivatives can also be suitably used. Further, metal phthalocyanines such as copper phthalocyanine and fluorine-substituted copper phthalocyanine described in JP-A-11-251601, naphthalene 1,4,5,8-tetracarboxylic diimide, N, N'-bis (4-trifluoromethyl N, N′-bis (1H, 1H-perfluorooctyl), N, N′-bis (1H, 1H-perfluorobutyl) and N, N with benzyl) naphthalene 1,4,5,8-tetracarboxylic diimide '-Dioctylnaphthalene 1,4,5,8-tetracarboxylic diimide derivative, naphthalene tetracarboxylic diimides such as naphthalene 2,3,6,7 tetracarboxylic diimide, and anthracene 2,3,6,7-tetra Condensed ring tetracars such as anthracenetetracarboxylic diimides such as carboxylic diimides Examples include: boric acid diimides, fullerenes such as C60, C70, C76, C78, and C84; carbon nanotubes such as SWNT; and dyes such as merocyanine dyes and hemicyanine dyes. Other organic semiconductor materials include tetrathiafulvalene (TTF) -tetracyanoquinodimethane (TCNQ) complex, bisethylenetetrathiafulvalene (BEDTTTTF) -perchloric acid complex, BEDTTTTF-iodine complex, TCNQ-iodine complex, and the like. Can also be used. Further, σ-conjugated polymers such as polysilane and polygermane, and organic / inorganic hybrid materials described in JP-A-2000-260999 can also be used.
[0015]
Among the π-conjugated polymers and π-conjugated oligomers, thiophene, vinylene, chenylenevinylene, phenylenevinylene, p-phenylene, a substituted product thereof, or two or more thereof are used as a repeating unit, and the number of the repeating unit ( It is preferable that at least one selected from the group consisting of oligomers in which n) is 2 to 15 or polymers in which the number (n) of the repeating units is 20 or more, and condensed polycyclic aromatic compounds such as pentacene. Further, a material having a three-dimensional regular structure in which a substituent such as a C4 to C15 alkyl group is added to at least one of the repeating units is preferable.
[0016]
From the viewpoint of appropriately imparting the three-dimensional regular structure to a polymer or an oligomer, the addition of a substituent such as an alkyl group enhances the solubility of the organic semiconductor material in an organic solvent, resulting in the formation of an organic semiconductor layer. It is effective in imparting regularity to the higher-order structure of the polymer.
[0017]
(Π-conjugated polymer having thiophene structure, π-conjugated oligomer)
Among the above-mentioned π-conjugated materials, the most preferred are polymers or oligomers having a thiophene ring chain structure, and more preferably used are polymers or oligomers having a 3-substituted thiophene ring as a repeating unit. Preferred are polymers or oligomers having a 3-alkyl-substituted thiophene ring as a repeating unit.
[0018]
(Alkyl group of 3-alkyl-substituted thiophene)
The method for producing an organic thin film transistor of the present invention (a method for producing a thin film) will be described later, but a method for preparing a coating liquid containing an organic semiconductor material and then applying the coating liquid improves productivity. It is preferably used from the viewpoint that the thin film production can be precisely controlled. In this case, the solubility in various organic solvents and the like used for preparing the coating liquid is improved, and the thiophene ring repetition of the semiconductor material after film formation is performed. From the viewpoint of forming a film so that the unit exhibits a specific regioregularity, the alkyl group of the 3-alkylthiophene ring is preferably a straight-chain alkyl group having 4 to 15 carbon atoms. In order to adjust the transition temperature of the organic semiconductor material in the semiconductor layer to the liquid crystal layer to 240 ° C. or lower, and to make a general-purpose resin usable as a support, a straight-chain catalyst having 6 or more carbon atoms is required. Preferably Kill group, particularly preferably an alkyl group having 8 to 12 carbon atoms of straight-chain.
[0019]
(Regioregular poly (3-alkylthiophene))
As the polythiophene according to the present invention, a polythiophene having a repeating unit (also referred to as a sequence) having a 3-alkyl-substituted thiophene ring is preferably used. Among the above-mentioned 3-alkyl-substituted polythiophenes, particularly preferred is a regioregular polythiophene. (Regio regular) poly (3-alkylthiophene).
[0020]
Examples of the polythiophene used in the present invention include JP-A-10-190001, Nature, vol. 41, p. 685 (1999), Appl. Phys. Lett. 69, p4108 (1996) and the like.
[0021]
(Molecular weight of polythiophene)
The weight average molecular weight of the polythiophene according to the present invention is preferably in the range of 500 to 5,000,000, and more preferably in the range of 1,000 to 100,000.
[0022]
The organic thin-film transistor of the present invention provides the effect described in the present invention, that is, an organic thin-film transistor that has high carrier (electron or hole) mobility and can use a general-purpose plastic, transparent resin, or the like as a support. For this purpose, it is essential that at least one type of phase transition temperature (° C.) of the organic semiconductor material is equal to or lower than a glass transition point (° C.) of at least one type of resin constituting a support described later. .
[0023]
In the present invention, the phase transition temperature of the organic semiconductor material is a melting point.
In particular, the melting point of the organic semiconductor material is preferably equal to or lower than the glass transition point (° C.) of at least one resin constituting the support.
[0024]
Regarding the measurement of the above melting point, the phase transition behavior can be examined by a commercially available automatic melting point measuring device.
[0025]
Examples of the method for producing the organic semiconductor layer (organic thin film) according to the present invention include a vacuum deposition method, a molecular beam epitaxial growth method, an ion cluster beam method, a low energy ion beam method, an ion plating method, a CVD (Chemical Vapor Deposition) method, Sputtering method, plasma polymerization method, electrolytic polymerization method, chemical polymerization method, spray coating method, spin coating method, blade coating method, dip coating method, casting method, roll coating method, bar coating method, die coating method, inkjet method and LB method And the like, and can be used depending on the material.
[0026]
However, in view of the above, from the viewpoint of improving productivity, an organic semiconductor material is dissolved in an appropriate organic solvent, and a spin coating method, a blade coating method, a dip coating method that can easily and accurately form a thin film using the prepared solution. Preferred examples of the method for forming the organic semiconductor layer include a roll coating method, a bar coating method, a die coating method, and an inkjet method.
[0027]
After the organic semiconductor layer is formed, the semiconductor material is heated to a phase transition temperature of the organic semiconductor material, that is, the melting point or higher to cause the semiconductor material to undergo phase transition, and then cooled and solidified to form a semiconductor layer. In cooling and solidifying, it is preferable to gradually cool at a rate of 0.1 ° C./sec to 1.0 ° C./sec. The effect of improving the field-effect mobility of carriers in the organic semiconductor layer is obtained by slow cooling.
[0028]
(Thickness of organic semiconductor layer)
The thickness of the organic semiconductor thin film is not particularly limited, but the characteristics of the obtained transistor are often greatly influenced by the thickness of the active layer made of the organic semiconductor. Although it depends on the semiconductor, it is generally preferably 1 μm or less, particularly preferably in the range of 10 nm to 300 nm.
[0029]
An organic thin-film transistor has a source electrode and a drain electrode connected by an organic semiconductor channel on a support, and a top-gate type having a gate electrode therethrough via a gate insulating layer, and a gate electrode on the support first. And a bottom gate type having a source electrode and a drain electrode connected by an organic semiconductor channel via a gate insulating layer.
[0030]
On the other hand, FIG. 1 shows an example of a position where the light-to-heat conversion layer is introduced.
FIG. 1A shows that a photothermal conversion layer 7 is formed on a support 1, a source electrode 3 and a drain electrode 4 connected by an organic semiconductor channel 2 are provided thereon, and a gate electrode is further provided via a gate insulating layer 5. 6 is an example of a top-gate type provided with 6.
[0031]
FIG. 1B shows a light-to-heat conversion layer 7 formed on a support 1, a gate electrode 6 provided thereon, and a source electrode 3 and a drain electrode 4 connected by an organic semiconductor channel 2 via a gate insulating layer 5. FIG. 1C shows an example in which the light-to-heat conversion layer 7 is formed as the uppermost layer in the bottom gate type.
[0032]
FIG. 1D shows a photothermal conversion layer 7 formed on a support 1, a gate electrode 6 provided thereon, a gate insulating layer 5, an organic semiconductor layer (channel) 2 formed thereon, and a source electrode formed thereon. This is an example of a bottom gate type provided with a drain electrode 3 and a drain electrode 4.
[0033]
FIG. 1E shows that a gate electrode 6 is provided on a support 1, a gate insulating layer 5 and an organic semiconductor layer (channel) 2 are formed thereon, and a source electrode 3 and a drain electrode 4 are provided. This is an example in which a photothermal conversion layer 7 covering the drain electrode 4 is formed. As shown in FIG. 1F, the light-to-heat conversion layer 7 may be formed by covering the source electrode 3 and the drain electrode 4 with a protective layer 8.
[0034]
In addition, about what does not have a light-to-heat conversion layer and melts by heating, the light-to-heat conversion layer may be omitted from the above.
[0035]
In the present invention, the material for forming the source electrode 3, the drain electrode 4, and the gate electrode 6 is not particularly limited as long as it is a conductive material, and platinum, gold, silver, nickel, chromium, copper, iron, tin, antimony lead, Tantalum, indium, palladium, tellurium, rhenium, iridium, aluminum, ruthenium, germanium, molybdenum, tungsten, tin / antimony, indium / tin oxide (ITO), fluorine-doped zinc oxide, zinc, carbon, graphite, glassy carbon, silver Paste and carbon paste, lithium, beryllium, sodium, magnesium, potassium, calcium, scandium, titanium, manganese, zirconium, gallium, niobium, sodium, sodium-potassium alloy, magnesium, lithium, aluminum, magnesium A nesium / copper mixture, a magnesium / silver mixture, a magnesium / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide mixture, a lithium / aluminum mixture, and the like are used. In particular, platinum, gold, silver, copper, aluminum, indium, ITO and carbon are preferred. Alternatively, a known conductive polymer whose conductivity has been improved by doping or the like, for example, conductive polyaniline, conductive polypyrrole, conductive polythiophene, a complex of polyethylene dioxythiophene and polystyrene sulfonic acid, or the like is also preferably used. Among them, those having low electric resistance at the contact surface with the semiconductor layer are preferable.
[0036]
As a method of forming an electrode, a method of forming an electrode using a known photolithographic method or a lift-off method on a conductive thin film formed by using a method such as evaporation or sputtering using the above as a raw material, or a metal foil such as aluminum or copper There is a method of etching using a resist by thermal transfer, ink jet or the like. A solution or dispersion of a conductive polymer or a dispersion of conductive fine particles may be directly patterned by ink jet, or may be formed from a coating film by lithography or laser ablation. Further, a method of patterning an ink, a conductive paste, or the like containing a conductive polymer or conductive fine particles by a printing method such as letterpress, intaglio, lithographic, or screen printing can also be used.
[0037]
Various insulating films can be used as the gate insulating layer 6, and an inorganic oxide film having a high relative dielectric constant is particularly preferable. As the inorganic oxide, silicon oxide, aluminum oxide, tantalum oxide, titanium oxide, tin oxide, vanadium oxide, barium strontium titanate, barium zirconate titanate, lead zirconate titanate, lead lanthanum titanate, strontium titanate, Examples include barium titanate, barium magnesium fluoride, bismuth titanate, strontium bismuth titanate, strontium bismuth tantalate, bismuth tantalate bismuth, and yttrium trioxide. Among them, preferred are silicon oxide, aluminum oxide, tantalum oxide and titanium oxide. Inorganic nitrides such as silicon nitride and aluminum nitride can also be suitably used.
[0038]
Examples of the method for forming the film include a vacuum deposition method, a molecular beam epitaxial growth method, an ion cluster beam method, a low energy ion beam method, an ion plating method, a CVD method, a dry process such as a sputtering method and an atmospheric pressure plasma method, and a spray method. Wet processes such as a coating method, a spin coating method, a blade coating method, a dip coating method, a casting method, a coating method such as a roll coating method, a bar coating method, a die coating method, and a patterning method such as printing or inkjet, Can be used depending on the material.
[0039]
The wet process is a method in which fine particles of an inorganic oxide are dispersed in an optional organic solvent or water using a dispersing aid such as a surfactant, if necessary, and a method of drying, or a method of drying an oxide precursor, for example, A so-called sol-gel method of applying and drying a solution of the alkoxide compound is used.
[0040]
Of these, the atmospheric pressure plasma method and the sol-gel method are preferred.
The method of forming an insulating film by plasma film formation under atmospheric pressure is a process of forming a thin film on a substrate by discharging under an atmospheric pressure or a pressure close to the atmospheric pressure, exciting a reactive gas by plasma, and forming a thin film on the substrate. The method is described in JP-A-11-61406, JP-A-11-133205, JP-A-2000-121804, JP-A-2000-147209, and JP-A-2000-185362 (hereinafter also referred to as atmospheric pressure plasma method). Thereby, a highly functional thin film can be formed with high productivity.
[0041]
As the organic compound film, polyimide, polyamide, polyester, polyacrylate, photo-radical polymerization type, photo-cationic polymerization type photo-curable resin, or copolymer containing acrylonitrile component, polyvinyl phenol, polyvinyl alcohol, novolak resin, And cyanoethyl pullulan can also be used.
[0042]
As the method for forming the organic compound film, the wet process is preferable.
The inorganic oxide film and the organic oxide film can be laminated and used together. The thickness of these insulating films is generally 50 nm to 3 μm, preferably 100 nm to 1 μm.
[0043]
The support 1 is made of a sheet made of glass or a flexible resin. For example, a plastic film can be used as the sheet. Examples of the plastic film include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyether sulfone (PES), polyether imide, polyether ether ketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate (PC), Examples include a film made of cellulose triacetate (TAC), cellulose acetate propionate (CAP), and the like. As described above, by using a plastic film, the weight can be reduced as compared with the case of using a glass substrate, portability can be improved, and resistance to impact can be improved.
[0044]
In addition, as shown in FIGS. 2 (d ′), (e ′) and (f ′), in the configuration of FIGS. 1 (d), (e) and (f), the organic semiconductor layer is arranged adjacent to the alignment film 9. Also preferably formed. Adjacent to the alignment film 9 is preferable because molecular alignment is promoted by heat treatment of the organic semiconductor layer by photothermal conversion, and the mobility of the organic semiconductor channel is further improved.
[0045]
As the alignment film, a known technique used for a liquid crystal display or the like, for example, a technique described in JP-A-9-194725 or 9-258229 can be used. Polyimide, a perfluoropolymer, a liquid crystal polymer, or the like is used as a material of the alignment film, and it is preferable to perform a rubbing treatment after forming the film. The method of orientation in an electromagnetic field described in U.S. Pat. No. 5,468,519 may be used.
[0046]
Preferably, the alignment film is photo-aligned, and is an alignment film described in JP-A-8-286180, JP-A-8-313910, JP-A-9-80440, or the like.
[0047]
The thickness of the alignment film is about 1 nm to 5 μm, preferably 5 to 100 nm.
FIG. 3 shows another preferred example, in which a gate electrode 6 is provided on a support 1, a gate insulating layer 5 and a photothermal conversion layer 7 are formed thereon, and a source electrode 3 and a drain electrode 4 are provided. This is an example in which an organic semiconductor layer (channel) 2 covering a drain electrode 4 is formed. By doing so, the photothermal conversion layer 7 also functions as a gate insulating layer.
[0048]
As the light-to-heat conversion agent used in the light-to-heat conversion layer 7, a conventionally known near-infrared light absorber can be used. Organic compounds such as dyes, phthalocyanine-based, azo-based, and thioamide-based organometallic complexes are suitably used, and specifically, JP-A-63-139191, JP-A-64-33547, and JP-A-1-160683. Nos. 1-280750, 1-293342, 2-2074, 3-26593, 3-30991, 3-34891, 3-36093, 3-36094, The compounds described in 3-36095, 3-42281, 3-97589 and 3-103476 can be mentioned. These can be used alone or in combination of two or more. Further, carbon black and the like are also preferable. The light-to-heat conversion layer can be obtained by dispersing or dissolving these light-to-heat conversion agents in a resin solution, coating and drying, or kneading and stretching the light-to-heat conversion agent in a resin to form a film.
[0049]
As a coating method of the light-to-heat conversion layer, a known coating method such as dipping, spin coating, knife coating, bar coating, blade coating, squeeze coating, reverse roll coating, gravure roll coating, curtain coating, spray coating, and die coating may be used. And a coating method capable of continuous coating or thin film coating is preferably used.
[0050]
High illuminance light is used as a light source used for the photothermal conversion method, and there is no particular limitation.Preferably, a laser beam is used.However, xenon lamps, halogen lamps, flash exposure using a mercury lamp, or the like may be performed through a mask. good. In the case of laser light, it is preferably used because it can be squeezed into a beam shape, and can be subjected to scanning exposure according to the purpose. be able to.
[0051]
In addition, in order to obtain high resolution by exposure with laser light, an electromagnetic wave whose energy application area can be narrowed down, particularly ultraviolet light having a wavelength of 1 nm to 1 mm, visible light, or infrared light is preferable. Known solid-state lasers such as ruby laser, YAG laser, and glass laser; He-Ne laser, Ar ion laser, Kr ion laser, CO ₂ Laser, CO laser, He-Cd laser, N ₂ Lasers, gas lasers such as excimer lasers; InGaP lasers, AlGaAs lasers, GaAsP lasers, InGaAs lasers, InAsP lasers, CdSnP ₂ A semiconductor laser such as a laser and a GaSb laser; a chemical laser and a dye laser; and among these, a semiconductor laser having a wavelength of 700 to 1200 nm is preferable.
[0052]
An infrared laser having an output per laser beam of 20 to 200 mW is most preferably used. The energy density is preferably 50 to 500 mJ / cm. ² And more preferably 100 to 200 mJ / cm ² It is.
[0053]
FIG. 4 is a schematic equivalent circuit diagram of the organic thin film transistor sheet 10 of the present invention.
[0054]
The organic thin film transistor sheet 10 has a large number of organic thin film transistor elements 14 arranged in a matrix. Reference numeral 11 denotes a gate bus line of a gate electrode of each organic thin film transistor element 14, and reference numeral 12 denotes a source bus line of a source electrode of each organic thin film transistor element 14. An output element 16 is connected to a drain electrode of each organic thin film transistor element 14, and the output element 16 is, for example, a liquid crystal, an electrophoretic element, or the like, and constitutes a pixel in a display device. In the illustrated example, liquid crystal is shown as an output element 16 by an equivalent circuit including a resistor and a capacitor. Reference numeral 15 denotes a storage capacitor, 17 denotes a vertical drive circuit, and 18 denotes a horizontal drive circuit.
[0055]
FIG. 5 shows light irradiation sites for various electrode arrangements. FIGS. 5A, 5B, and 5C show portions irradiated with light with respect to various gate, source, and drain electrode pattern shapes. Reference numeral 21 denotes a gate electrode, reference numeral 22 denotes a source electrode, reference numeral 23 denotes a drain electrode (also serving as a display electrode) pattern, and reference numeral 24 denotes an area irradiated with light. Each layer such as the above-mentioned gate insulating layer, organic semiconductor layer, light-to-heat conversion layer and the like is omitted in the figure for simplification of description.
[0056]
In FIG. 5A, a projection 23a is provided on the drain electrode, and the area of the hatched portion 24 is irradiated with light so as to overlap the three of the gate electrode 21 and the source electrode 22 to perform photothermal conversion. In FIG. 5B, a protruding portion 22a is provided on the source electrode, and the area of the hatched portion 24 is irradiated with light so that the three of the gate electrode 21 and the drain electrode 23 are overlapped to perform photothermal conversion. In FIG. 5C, a projection 21a is provided on the gate electrode, and the area of the hatched portion 24 is irradiated with light so that the three of the source electrode 22 and the drain electrode 23 are overlapped with each other to perform photothermal conversion.
[0057]
FIG. 6 shows an example of a light irradiation area when arranged in a matrix. Here, for example, a large number of the pattern shapes shown in FIG. 5B are arranged in a matrix, and six of them are extracted from the matrix shape, and the hatched portion is irradiated with light similarly to FIG. In such a regular arrangement, a method of continuously irradiating using an optical scanning device and an XY stage, or a single exposure with high illuminance light through a mask having a light-irradiated portion opened. And the like, a sheet in which thin film transistors are arranged in a matrix can be easily manufactured.
[0058]
When the light-to-heat conversion layer is not provided, the whole is heated and melted to form an organic TFT sheet. When the influence between the elements becomes problematic, the effect is realized by separating the elements with laser light. It is also possible to make no problem in use.
[0059]
That is, as described above, the number of patterning steps in a TFT sheet in which TFTs are two-dimensionally arranged is reduced, and substantial patterning can be performed by a simple method, so that a low-cost TFT sheet can be provided.
[0060]
【Example】
Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto.
[0061]
<Example 1>
After forming a thermal oxide film having a thickness of 200 nm on a Si wafer having a specific resistance of 0.01 Ω · cm, a chloroform solution of well-purified regioregular poly- (3-hexylthiophene) is applied using an applicator and air-dried. Then, a cast film (thickness: 50 nm) was formed. Heat treatment was performed at 50 ° C. for 30 minutes in a nitrogen atmosphere. Further, gold was deposited on the surface of the poly (3-hexylthiophene) film using a mask to form source and drain electrodes. The source and drain electrodes having a width of 100 μm and a thickness of 100 nm were arranged so as to be perpendicular to the gate electrode, and an organic thin-film transistor element having a channel width W = 0.3 mm and a channel length L = 20 μm was formed. The device was heated to 250 ° C. and melted in a nitrogen atmosphere, cooled to 150 ° C. at a rate of −0.1 ° C./sec, and cooled to room temperature in a nitrogen gas flow.
[0062]
This organic thin-film transistor element exhibited favorable operation characteristics of the p-channel enhancement type FET.
[0063]
Ten devices were manufactured, and the mobility in the saturation region was measured. As a comparative example, a non-melting element was also prepared and evaluated in the same manner, and the average value, maximum value, and minimum value are shown in FIG.
[0064]
The relationship between the cooling rate up to 150 ° C. and the mobility was measured, and the results are shown in FIG.
[0065]
From the above results, it was confirmed that the organic thin film transistor that was heated and melted and cooled had higher mobility and less variation in production. It was also confirmed that good operation characteristics could be maintained at a cooling rate of -1 ° C / sec or less.
[0066]
<Example 2>
FIG. 9 shows a film forming order, and the description will be made according to this order.
[0067]
After a photosensitive resist for photolithography was applied on a polyethersulfone (PES) film support 1 having a thickness of 200 μm, a gate bus line (electrode) 31 having a width of 20 μm was formed by a lift-off method. The gate bus line (electrode) 31 was formed by sputtering Al to a thickness of 200 nm (FIG. 9A).
[0068]
Next, a silicon oxide film having a thickness of 200 nm is provided on the entire surface as a gate insulating layer 32 by an atmospheric pressure plasma method (FIG. 9B), and a well purified xylene dispersion of a regular-type poly- (3-hexylthiophene) is applied to an organic layer. It was applied as a semiconductor layer 33 (FIG. 9C). The dry film thickness at this time is 20 nm.
[0069]
Next, gold 34 having a thickness of 500 nm was deposited in a shape shown in FIG. 9D through a mask. Further, a MEK solution of polyethylene glycol having a weight-average molecular weight of 30,000 was applied to a thickness of 300 nm, and a dispersion of PVA and carbon black (mass ratio 5: 1) was prepared thereon, followed by coating and drying to obtain a thickness of 500 nm. Was formed.
[0070]
Although the TFT manufactured as described above did not operate, a 10 mW laser diode was used from the front side (front side of the paper) to a rectangular portion surrounded by a broken line indicated by 35 in FIG. ² Irradiation with infrared light having a wavelength of 830 nm at an energy density of .mu.m showed that p-channel enhancement-type FETs (field-effect transistors) exhibited good operating characteristics.
[0071]
<Example 3>
In the process of Example 2, a chloroform solution of a periodic-type poly- (3-hexylthiophene) was applied as an organic semiconductor layer, melted by heating, and cooled at −10 ° C./sec.
[0072]
In this state, as described in FIG. 8, the cooling rate was too high and the device did not operate. However, when the same portion as in Example 2 was irradiated with infrared light, the favorable characteristics of the p-channel enhancement type FET were confirmed. Was confirmed.
[0073]
【The invention's effect】
As described above, a TFT having a high mobility and capable of being manufactured stably and a manufacturing method thereof, and a patterning step in a TFT sheet in which TFTs are two-dimensionally arranged are reduced, so that a TFT can be substantially manufactured by a simple method. Patterning has become possible, and a low-cost TFT sheet can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a position where a light-to-heat conversion layer is introduced.
FIG. 2 is a diagram illustrating an example in which an organic semiconductor layer is formed adjacent to an alignment film.
FIG. 3 is a diagram showing another preferred layer configuration example.
FIG. 4 is a schematic equivalent circuit diagram of a transistor sheet.
FIG. 5 is a diagram showing light irradiation sites for various electrode arrangements.
FIG. 6 is a diagram showing an example of a light irradiation area when arranged in a matrix.
FIG. 7 is a diagram showing the average value, the maximum value, and the minimum value of the mobility measured in a saturation region.
FIG. 8 is a diagram illustrating the relationship between the cooling rate and the mobility, and the result of the measurement.
FIG. 9 is a diagram showing a film forming order in Example 2.
[Explanation of symbols]
1 Support
2 Organic semiconductor layer (channel)
3 Source electrode
4 Drain electrode
5 Gate insulating layer
6 Gate electrode
7 Light-to-heat conversion layer
8 Protective layer
9 Alignment film

Claims (18)

A method for manufacturing an organic thin film transistor element, wherein an organic semiconductor layer is formed through a step of heating and melting an organic semiconductor material. 2. The method according to claim 1, wherein the organic semiconductor material is a π-conjugated polymer or oligomer in which an alkyl group possesses an array structure. The method according to claim 1, further comprising a cooling step after the heating and melting step, wherein a cooling rate is set to 1 ° C./second or less. The method according to any one of claims 1 to 3, wherein the heating and melting step is performed by providing a light-to-heat conversion layer and irradiating light. The method according to any one of claims 1 to 4, wherein the light irradiation is performed by a laser. The method for manufacturing an organic thin film transistor device according to claim 1, further comprising an alignment film adjacent to the organic semiconductor layer. Having a support, a gate electrode, a gate insulating layer, a source electrode, a drain electrode, and an organic semiconductor material;
An organic thin film transistor element, wherein an organic semiconductor layer is formed by heating and melting the organic semiconductor material. The organic thin-film transistor element according to claim 7, wherein the organic semiconductor material is a π-conjugated polymer or oligomer in which an alkyl group possesses an array structure. The organic thin-film transistor element according to claim 7, wherein the organic thin-film transistor element is cooled after the heating and melting, and the cooling rate is 1 ° C./second or less. The organic thin-film transistor element according to any one of claims 7 to 9, wherein the heating and melting are performed by providing a light-to-heat conversion layer and irradiating light. The organic light-emitting device according to any one of claims 7 to 10, wherein the light irradiation is performed by a laser. The organic thin-film transistor element according to claim 7, further comprising an alignment film adjacent to the organic semiconductor layer. Having a gate electrode, a gate insulating layer, a source electrode, a drain electrode, and an organic semiconductor material on a sheet-shaped support;
An organic thin film transistor sheet wherein a plurality of organic thin film transistors on which an organic semiconductor layer is formed by heating and melting the organic semiconductor material are arranged. 14. The organic thin film transistor sheet according to claim 13, wherein the organic semiconductor material is a π-conjugated polymer or oligomer in which an alkyl group possesses an array structure. The organic thin film transistor sheet according to claim 13 or 14, wherein the sheet is cooled after the heating and melting, and the cooling rate is 1 ° C / second or less. The organic thin film transistor sheet according to any one of claims 13 to 15, wherein the heating and melting are performed by providing a light-to-heat conversion layer and irradiating light. The organic thin film transistor element sheet according to any one of claims 13 to 16, wherein the light irradiation is performed by a laser. The organic thin film transistor sheet according to any one of claims 13 to 17, further comprising an alignment film adjacent to the organic semiconductor layer.

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