JP2008192669A - Organic semiconductor composition and manufacturing method of transistor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic semiconductor composition capable of forming an organic semiconductor layer having high preservation stability and superior characteristics, and a manufacturing method of a transistor by which a high-reliability transistor can be manufactured using this composition. <P>SOLUTION: This manufacturing method provides for a transistor 1 provided with a source electrode 20a, a drain electrode 20b, a gate electrode 50, an organic semiconductor layer 30 and a gate insulating film 40 for insulating the source electrode 20a and the drain electrode 20b from the gate electrode 50. The method includes a step of forming an organic semiconductor layer 30, by applying an organic semiconductor composition containing an organic semiconductor material, comprising a structure unit that contains at least one thiophene ring as a repeating unit and an organic solvent containing at least any one of sishydrindane, transhydrindane, 1,3-dimethyladamantan, exotetrahydrodicyclopentadiene or cineole. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an organic semiconductor composition and a method for producing a transistor.

In recent years, a thin film transistor using an organic semiconductor material has attracted attention as a device that can replace a thin film transistor using an inorganic semiconductor material (see, for example, Patent Document 1).
In this thin film transistor, a polymer organic semiconductor material having a thiophene ring is known as an organic semiconductor material. This organic semiconductor material has high carrier mobility, and since it is a polymer, it can be dissolved in an organic solvent to form an ink, and thus has an advantage that an organic semiconductor layer can be formed by a liquid phase process.

By the way, in the liquid phase process, an organic semiconductor layer is formed by applying an ink containing an organic semiconductor material to a predetermined organic semiconductor layer formation region and performing post-processing.
Here, in order to uniformly apply the ink and suppress variations among the formed organic semiconductor layers, the properties of the ink are important.
That is, the ink must be excellent in stability because it is difficult for the organic semiconductor material to precipitate. Further, it is necessary that the surface tension, viscosity, and boiling point of the ink are adjusted to an appropriate range according to the ink application method.
However, when an organic semiconductor material having a thiophene ring dissolves in an organic solvent, aggregation tends to occur around the thiophene ring over time, and the organic semiconductor material precipitates due to this aggregation, making it difficult to obtain a stable ink. There is a problem that.
Japanese Patent Laid-Open No. 2004-6682

  The present invention has been made in view of such circumstances, and a composition for organic semiconductors capable of forming an organic semiconductor layer having high storage stability and excellent characteristics, and a reliability produced using the same. It is an object of the present invention to provide a method for manufacturing a transistor capable of manufacturing a high-performance transistor.

Such an object is achieved by the present invention described below.
An organic semiconductor composition of the present invention comprises an organic semiconductor material having a structural unit containing at least one thiophene ring as a repeating unit, cishydrindan, transhydrindan, 1,3-dimethyladamantane, exotetrahydrodicyclopentadiene, or cineol. And an organic solvent containing at least one of the following.

  According to the composition for organic semiconductors of the present invention, the composition for organic semiconductors can form an organic semiconductor layer having high storage stability and excellent characteristics.

In the organic semiconductor composition, the structural unit preferably includes a π-conjugated structure on the main chain.
According to this configuration, the π-conjugated structure can prevent a decrease in the carrier mobility of the molecule due to the inclusion in the structure, thereby preventing a decrease in the carrier mobility of the organic semiconductor layer. It becomes.
The π-conjugated structure is preferably a fluorene ring. In this case, since the fluorene ring has a particularly high carrier mobility, a decrease in carrier mobility caused by the fluorene ring can be particularly reliably prevented.
Furthermore, the structural unit preferably includes an alkyl chain, and the alkyl chain is preferably bonded to the fluorene ring. In this case, since at least an alkyl chain can be prevented from bonding to the thiophene ring, the structure of the thiophene ring can be maintained. Accordingly, it is possible to reliably prevent the semiconductor characteristics of the thiophene ring from deteriorating.

Moreover, in the composition for organic semiconductors of this invention, it is preferable that the said structural unit contains an alkyl chain.
Thereby, the affinity with respect to a general organic solvent increases, and the solubility to the organic solvent of an organic-semiconductor material improves.

Moreover, in the composition for organic semiconductors of this invention, it is preferable that carbon number of the said alkyl chain is 4-20.
Thereby, the solubility with respect to the organic solvent of organic-semiconductor material can fully be maintained.

Moreover, in the composition for organic semiconductors of this invention, it is preferable that the average number of the said repeating units in the said organic-semiconductor material is 2-500.
This makes it easy to synthesize and handle while exhibiting sufficient characteristics as a semiconductor material.

Moreover, in the composition for organic semiconductors of this invention, it is preferable that the content rate of the said organic-semiconductor material is 0.1-5 wt%.
Thereby, an organic semiconductor layer having a sufficient thickness can be formed while reliably preventing the organic semiconductor material from being deposited.

  According to another aspect of the present invention, there is provided a method for manufacturing a transistor comprising: a source electrode; a drain electrode; a gate electrode; an organic semiconductor layer; and a gate insulating film that insulates the source electrode and the drain electrode from the gate electrode. An organic semiconductor material having a structural unit containing at least one thiophene ring as a repeating unit, and at least one of cishydrindan, transhydrindane, 1,3-dimethyladamantane, exotetrahydrodicyclopentadiene, or cineol The organic semiconductor layer is formed by applying a composition for organic semiconductor containing an organic solvent containing the organic semiconductor layer.

  According to the method for producing a transistor of the present invention, a transistor having excellent transistor characteristics and durability and high reliability can be obtained.

Hereinafter, an embodiment of the composition for organic semiconductor of the present invention and a method for producing a transistor will be described with reference to the drawings.
(First embodiment)
First, 1st Embodiment of the thin-film transistor manufactured using the composition for organic semiconductors of this invention is described.

FIG. 1 is a schematic view showing a first embodiment of a thin film transistor manufactured using the composition for organic semiconductor of the present invention ((a) is a longitudinal sectional view, (b) is a plan view) in FIG. 2 and 3 are views (longitudinal sectional views) for explaining a method of manufacturing the thin film transistor shown in FIG.
A thin film transistor (transistor of the present invention) 1 shown in FIG. 1 is a top-gate thin film transistor, and is provided so as to cover a source electrode 20a and a drain electrode 20b provided separately from each other, and a source electrode 20a and a drain electrode 20b. The organic semiconductor layer 30 and the gate insulating layer 40 positioned between the organic semiconductor layer 30 and the gate electrode 50 are provided on the substrate 10.

Hereinafter, the configuration of each unit will be sequentially described.
The substrate 10 supports each layer (each part) constituting the thin film transistor 1.
The substrate 10 includes, for example, a plastic substrate (glass substrate, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), aromatic polyester (liquid crystal polymer), polyimide (PI), etc. Resin substrate), quartz substrate, silicon substrate, metal substrate, gallium arsenide substrate, and the like can be used.

When the thin film transistor 1 is given flexibility, a plastic substrate or a thin (relatively small film thickness) metal substrate is selected as the substrate 10.
On the substrate 10, a source electrode 20a and a drain electrode 20b (a pair of electrodes) are provided. That is, the source electrode 20a and the drain electrode 20b are provided on substantially the same plane.

As a constituent material of the source electrode 20a and the drain electrode 20b, for example, Au, Ag, Cu, Pt, Ni, Cr, Ti, Ta, Al or a metal material such as an alloy containing these, and oxides thereof are used. Can be used.
Moreover, the source electrode 20a and the drain electrode 20b can also be comprised with an electroconductive organic material.

  When the organic semiconductor layer 30 is p-type, the constituent materials of the source electrode 20a and the drain electrode 20b are preferably mainly composed of Au, Ag, Cu, Pt, or an alloy containing these, respectively. Since these have a relatively large work function, the efficiency of injecting holes (carriers) into the organic semiconductor layer 30 can be improved by forming the source electrode 20a with these materials.

In addition, although the average thickness of the source electrode 20a and the drain electrode 20b is not specifically limited, It is preferable that it is about 10-2000 nm, respectively, and it is more preferable that it is about 50-1000 nm.
The distance between the source electrode 20a and the drain electrode 20b, that is, the channel length L shown in FIG. 1 is preferably about 2 to 30 μm, and more preferably about 2 to 20 μm. By setting the value of the channel length L in such a range, the characteristics of the thin film transistor 1 can be improved (in particular, the ON current value can be increased).

  Further, the length of the source electrode 20a and the drain electrode 20b, that is, the channel width W shown in FIG. 1, is preferably about 0.1 to 5 mm, and more preferably about 0.3 to 3 mm. By setting the value of the channel width W in such a range, the parasitic capacitance can be reduced, and deterioration of the characteristics of the thin film transistor 1 can be prevented. In addition, an increase in size of the thin film transistor 1 can be prevented.

An organic semiconductor layer 30 is provided on the substrate 10 so as to be in contact with each source electrode 20a and drain electrode 20b.
The constituent material of the organic semiconductor layer 30 will be described in the thin film transistor manufacturing method described later.
The average thickness of the organic semiconductor layer 30 is not particularly limited, but is preferably about 0.1 to 1000 nm, more preferably about 1 to 500 nm, and further preferably about 1 to 100 nm.

A gate insulating layer (insulator layer) 40 is provided on the organic semiconductor layer 30, that is, on the side opposite to the source electrode 20 a and the drain electrode 20 b via the organic semiconductor layer 30.
The gate insulating layer 40 insulates a gate electrode (third electrode) 50 described later from the source electrode 20a and the drain electrode 20b.
The constituent material of the gate insulating layer 40 is not particularly limited as long as it is a known gate insulator material, and either an organic material or an inorganic material can be used.

Examples of the organic material include polymethyl methacrylate, polyvinyl phenol, polyimide, polystyrene, polyvinyl alcohol, polyvinyl acetate, polyvinyl phenol, and the like, and one or more of these can be used in combination.
On the other hand, examples of the inorganic material include metal oxides such as silica, silicon nitride, aluminum oxide, and tantalum oxide, and metal composite oxides such as barium strontium titanate and lead zirconium titanate. A combination of more than one species can be used.

The average thickness of the gate insulating layer 40 is not particularly limited, but is preferably about 10 to 5000 nm, and more preferably about 100 to 2000 nm. By setting the thickness of the gate insulating layer 40 within the above range, the operating voltage of the thin film transistor 1 can be lowered while reliably insulating the source electrode 20a and the drain electrode 20b from the gate electrode 50.
Note that the gate insulating layer 40 is not limited to a single-layer structure, and may have a multilayer structure.

A gate electrode 50 that applies an electric field to the organic semiconductor layer 30 is provided at a predetermined position on the gate insulating layer 40, that is, at a position corresponding to a region between the source electrode 20 a and the drain electrode 20 b.
The material of the gate electrode 50 is not particularly limited as long as it is a known electrode material. Specifically, metal materials such as Cr, Al, Ta, Mo, Nb, Cu, Ag, Au, Pd, In, Ni, Nd, Co or alloys containing these, and oxides thereof are used. Can do.

Moreover, the gate electrode 50 can also be comprised with a conductive organic material.
The average thickness of the gate electrode 50 is not particularly limited, but is preferably about 0.1 to 2000 nm, and more preferably about 1 to 1000 nm.
In such a thin film transistor 1, when a gate voltage is applied to the gate electrode 50 with a voltage applied between the source electrode 20a and the drain electrode 20b, a channel is formed near the interface between the organic semiconductor layer 30 and the gate insulating layer 40. As a result, carriers (holes) move through the channel region, whereby a current flows between the source electrode 20a and the drain electrode 20b.

That is, in the OFF state in which no voltage is applied to the gate electrode 50, even if a voltage is applied between the source electrode 20a and the drain electrode 20b, almost no carriers are present in the organic semiconductor layer 30; Only flows.
On the other hand, in the ON state in which a voltage is applied to the gate electrode 50, charges are induced in the portion of the organic semiconductor layer 30 facing the gate insulating layer 40, and a channel (carrier flow path) is formed. When a voltage is applied between the source electrode 20a and the drain electrode 20b in this state, a current flows through the channel region.

Next, the composition for organic semiconductor of the present invention will be described by taking as an example the case of producing the thin film transistor shown in FIG.
1 includes a step [A1] of forming a source electrode 20a and a drain electrode 20b on a substrate 10, and a step of forming an organic semiconductor layer 30 so as to cover the source electrode 20a and the drain electrode 20b. [A2], a step [A3] of forming the gate insulating layer 40 on the organic semiconductor layer 30, and a step [A4] of forming the gate electrode 50 on the gate insulating layer 40.

[A1] Source and Drain Electrode Formation Step First, the source electrode 20a and the drain electrode 20b are formed on the substrate 10 (see FIG. 2A).
The source electrode 20a and the drain electrode 20b can be formed using, for example, an etching method, a lift-off method, or the like.

  When forming the source electrode 20a and the drain electrode 20b by etching, I: First, a metal film (metal layer) is formed on the entire surface of the substrate 10 by using, for example, sputtering, vapor deposition, plating, or the like. . II: Next, a resist layer is formed on the metal film (surface) by using, for example, a photolithography method, a microcontact printing method, or the like. III: Next, using this resist layer as a mask, the metal film is etched and patterned into a predetermined shape.

  When the source electrode 20a and the drain electrode 20b are formed by the lift-off method, I: First, a resist layer is formed in a region other than the region where the source electrode 20a and the drain electrode 20b are formed. II: Next, a metal film (metal layer) is formed on the entire surface of the substrate 10 on the resist layer side using, for example, vapor deposition or plating. III: Next, the resist layer is removed.

The source electrode 20a and the drain electrode 20b are formed on the substrate 10 by applying (supplying), for example, conductive particles or a conductive material containing a conductive organic material to form a coating film, and then as necessary. The film can also be formed by post-treatment (for example, heating, infrared irradiation, application of ultrasonic waves, etc.).
Examples of the conductive material containing conductive particles include a dispersion in which metal fine particles are dispersed, a polymer mixture containing conductive particles, and the like.
Moreover, as a conductive material containing a conductive organic material, a solution or dispersion of a conductive organic material can be given.

  Examples of methods for applying (supplying) a conductive material on the substrate 10 include spin coating, casting, micro gravure coating, gravure coating, bar coating, roll coating, wire bar coating, and dip coating. And coating methods such as spray coating method, screen printing method, flexographic printing method, offset printing method, ink jet method, printing method such as micro contact printing method, etc., one or more of these Can be used in combination.

[A2] Organic Semiconductor Layer Formation Step Next, the organic semiconductor layer 30 is formed so as to cover the source electrode 20a and the drain electrode 20b (see FIG. 2B).
The organic semiconductor layer 30 is formed by supplying a composition for an organic semiconductor containing an organic semiconductor material and an organic solvent so as to cover the source electrode 20a and the drain electrode 20b, and then performing post-processing as necessary. To do.

First, an organic semiconductor composition containing an organic semiconductor material and an organic solvent is prepared.
As the organic semiconductor material, an organic semiconductor material having a structural unit including at least one thiophene ring (hereinafter also simply referred to as “structural unit”) as a repeating unit is used. In such an organic semiconductor material, high carrier mobility can be obtained because the thiophene ring has a π-conjugated system. Therefore, a thin film transistor having excellent characteristics can be manufactured by using such an organic semiconductor material.

  However, an organic semiconductor material having a repeating unit of a structural unit containing at least one thiophene ring is likely to aggregate around the thiophene ring. For this reason, the composition for organic semiconductors formed by dissolving such an organic semiconductor material in an organic solvent is stable and stored as the organic semiconductor material aggregates and precipitates around the thiophene ring over time. I couldn't. For this reason, it is difficult to use for the formation of the organic semiconductor layer, and even if it can be used for the formation, there is a problem that the variation in the characteristics of each formed organic semiconductor layer is large.

  Therefore, the present inventor has conducted intensive studies on stably storing such a composition for organic semiconductors for a long period of time, and as a result, cis (cis) -hydrindane as an organic solvent for dissolving the organic semiconductor material as described above, The present invention is completed by finding that it is effective to use an organic solvent containing at least one of trans-hydrindane, 1,3-dimethyladamantane, exo-exo-tetrahydrodicyclopentadiene, or cineol. It came to.

  Here, the above-mentioned five materials have a specific steric structure and have a greater steric hindrance than a general organic solvent. Of the above materials, cishydrindan, exotetrahydrodicyclopentadiene, and cineol have particularly great steric hindrance. That is, when an organic semiconductor material having a repeating unit of a structural unit containing at least one thiophene ring is dissolved in an organic solvent containing the above material having a specific three-dimensional structure, the organic semiconductor material interferes with the above five materials ( Steric hindrance) prevents aggregation and precipitation around the thiophene ring. As a result, an organic semiconductor composition that is stable over a long period of time can be obtained.

And in the thin-film transistor 1 manufactured using such a stable composition for organic semiconductors, it is possible to prevent variation in individual characteristics and to improve reliability.
In general, the molecules constituting the organic semiconductor layer preferably have high planarity in the molecular structure. Thereby, the conjugation length in the molecule is increased, the intermolecular interaction is strengthened, and the crystallinity of the organic semiconductor layer is improved. As a result, carrier mobility in the organic semiconductor layer can be improved.

  Here, the organic semiconductor material preferably contains an alkyl chain. Thereby, the affinity with respect to a general organic solvent increases, and the solubility to the organic solvent of an organic-semiconductor material improves.

  Here, the organic solvent may contain a second substance other than the above five substances. Examples of the second substance include cyclohexane, cyclohexanone, 1,4-dioxane, indane, indene, ethylnaphthalene, methylnaphthalene, benzofuran, trimethylbenzene, xylene, toluene, cyclohexylbenzene, chlorobenzene, dichlorobenzene, tetrahydronaphthalene, butane. Hexane, heptane, octane, decane, dodecane, tetradecane, hexadecane and the like. By containing these second substances and controlling the content, the solubility in organic semiconductor materials and the stability of the composition for organic semiconductors can be further improved.

In addition, it is preferable that the content rate of the 3rd substance in an organic solvent is 10 wt% or less.
In addition, when the repeating unit of the organic semiconductor material includes an alkyl chain, the alkyl chain preferably has about 4 to 20 carbon atoms, and more preferably about 6 to 10 carbon atoms. Thus, while sufficiently maintaining the solubility of the organic semiconductor material in the organic solvent, the length of the alkyl chain between adjacent repeating units is such that the alkyl chains are not particularly likely to cause steric hindrance. can do. In addition, when it has a some alkyl chain in a repeating unit, carbon number of the above-mentioned alkyl chain means carbon number in one alkyl chain. Further, when the alkyl chain is branched in the middle, it means the number of carbon atoms from the base side bonded to the main chain to each branched end in the alkyl chain.

In addition, the structural unit including at least one thiophene ring as described above preferably includes a π-conjugated structure on the main chain. Since the π-conjugated structure functions to prevent a decrease in the carrier mobility of molecules due to the inclusion in the structure, this can prevent a decrease in the carrier mobility of the organic semiconductor layer. .
Such a π-conjugated structure is a structure in which single bonds and double bonds are alternately bonded, and examples thereof include a fluorene ring, a pyrrole ring, aniline, carbazole, acetylene, etc., and one of these or Two or more types can be used in combination, but a fluorene ring is particularly preferable. Since the fluorene ring has a particularly high carrier mobility, it is possible to reliably prevent a decrease in carrier mobility caused by the fluorene ring.

The alkyl chain may be bonded to the thiophene ring, but is preferably bonded to a site having a function of increasing the distance between the alkyl chains. Thereby, since it is possible to avoid the alkyl chain from being bonded to at least the thiophene ring, the structure of the thiophene ring can be maintained. Accordingly, it is possible to reliably prevent the semiconductor characteristics of the thiophene ring from deteriorating.
Specific examples of the organic semiconductor material as described above include a fluorene-bithiophene copolymer (F8T2) represented by the following chemical formula (1).

Since F8T2 has a relatively high ionization potential, it is difficult to be oxidized by oxygen or water in the air. Therefore, by configuring the organic semiconductor material using F8T2 as a main material, it is possible to form an organic semiconductor layer that is excellent in semiconductor characteristics and hardly deteriorates over time.
Examples of other organic semiconductor materials include poly (3-alkylthiophene) represented by the following chemical formula (2) such as poly (3-hexylthiophene) (P3HT) and poly (3-octylthiophene). These can be used alone, or can be used in combination with F8T2.

［式中、Ｒはアルキル鎖を表す］

[Wherein R represents an alkyl chain]

  Furthermore, as another organic semiconductor material, the compound represented by following Chemical formula (3)-(5) is also mentioned, for example, These can also be used independently and can also be used in combination with F8T2.

［式中、Ｒはアルキル鎖を表す］

[Wherein R represents an alkyl chain]

The average number n of repeating units in the organic semiconductor material is preferably about 2 to 500, more preferably about 2 to 100, and further preferably about 4 to 20. This makes it easy to synthesize and handle while exhibiting sufficient characteristics as a semiconductor material.
The content of the organic semiconductor material in the organic semiconductor composition is preferably about 0.1 to 5 wt%, and more preferably about 0.5 to 2 wt%. Thereby, an organic semiconductor layer having a sufficient thickness can be formed while reliably preventing the organic semiconductor material from being deposited.

Next, the organic semiconductor composition as described above is supplied onto the substrate 10 so as to cover the source electrode and the drain electrode.
As a method for supplying the liquid material for forming an organic semiconductor onto the substrate 10, for example, a coating method such as a spin coating method or a dip coating method, a printing method such as an ink jet printing method (droplet discharge method) or a screen printing method. Etc.

Of these, the inkjet method is preferably used. In the ink jet method, since a liquid material can be supplied in a fine pattern, patterning is unnecessary, and an organic semiconductor layer having a precise shape can be formed by a simple process.
The organic solvent used in the organic semiconductor composition of the present invention depends on the composition, but the boiling point of each of the above materials is sufficiently higher than room temperature. Can be prevented, and good discharge characteristics can be obtained.

  Specifically, the boiling point of cishydrindan is 166 ° C, the boiling point of transhydrindan is 159 ° C, the boiling point of 1,3-dimethyladamantane is 201 ° C, the boiling point of exotetrahydrodicyclopentadiene is 189 ° C, and the boiling point of cineol is 176 ° C. It has become.

In addition, when the organic semiconductor composition contains a precursor of an organic semiconductor material, an annealing treatment is performed thereafter.
Thereby, the organic semiconductor layer 30 is formed so as to cover the source electrode 20a and the drain electrode 20b. At this time, a channel region is formed between the source electrode 20a and the drain electrode 20b.

  The formation region of the organic semiconductor layer 30 is not limited to the illustrated configuration, and the organic semiconductor layer 30 may be selectively formed in a region (channel region) between the source electrode 20a and the drain electrode 20b. . Thereby, when a plurality of thin film transistors (elements) 1 are arranged on the same substrate, the leakage current and crosstalk between the elements are suppressed by independently forming the organic semiconductor layer 30 of each element. Can do. Moreover, the usage-amount of organic-semiconductor material can be reduced and manufacturing cost can also be reduced.

[A3] Gate Insulating Layer Formation Step Next, the gate insulating layer 40 is formed on the organic semiconductor layer 30 (see FIG. 3C).
For example, when the gate insulating layer 40 is made of an organic polymer material, the gate insulating layer 40 is applied (supplied) so as to cover the organic semiconductor layer 30 with a solution containing the organic polymer material or a precursor thereof. If necessary, the coating film can be formed by post-treatment (for example, heating, infrared irradiation, application of ultrasonic waves, etc.).

As a method for applying (supplying) a solution containing an organic polymer material or a precursor thereof onto the organic semiconductor layer 30, the application method, the printing method, and the like mentioned in the step [A2] can be used.
When the gate insulating layer 40 is made of an inorganic material, the gate insulating layer 40 can be formed by, for example, a thermal oxidation method, a CVD method, or an SOG method. Further, by using polysilazane as a raw material, a silica film and a silicon nitride film can be formed as a gate insulating layer 40 by a wet process.

[A4] Gate Electrode Formation Step Next, the gate electrode 50 is formed on the gate insulating film 40 (see FIG. 3D).
First, prior to forming the gate electrode 50, a metal film (metal layer) is formed.
This metal film is formed by, for example, chemical vapor deposition (CVD) such as plasma CVD, thermal CVD, laser CVD, vapor deposition, sputtering (low temperature sputtering), dry plating methods such as ion plating, electrolytic plating, immersion plating, electroless It can be formed by wet plating methods such as plating, thermal spraying methods, sol-gel methods, MOD methods, metal foil bonding, and the like.

Next, a resist material is applied on the metal film and then cured to form a resist layer having a shape corresponding to the shape of the gate electrode 50. Using this resist layer as a mask, unnecessary portions of the metal film are removed.
For the removal of the metal film, for example, one or more of physical etching methods such as plasma etching, reactive ion etching, beam etching, and optical assist etching, and chemical etching methods such as wet etching are used. They can be used in combination.
Then, the gate electrode 50 is obtained by removing the resist layer.

The gate electrode 50 is formed on the gate insulating layer 40 by, for example, applying (supplying) conductive particles or a conductive material containing a conductive organic material to form a coating film. It can also be formed by subjecting the coating film to post-treatment (for example, heating, infrared irradiation, application of ultrasonic waves, etc.).
Examples of the conductive material containing conductive particles include a dispersion in which metal fine particles are dispersed, a polymer mixture containing conductive particles, and the like.

Moreover, as a conductive material containing a conductive organic material, a solution or dispersion of a conductive organic material can be given.
As a method for applying (supplying) the conductive material on the gate insulating layer 40, for example, the application method, the printing method, or the like described in the step [A2] can be used.
Through the steps as described above, the thin film transistor 1 of the first embodiment is obtained.

(Second Embodiment)
Next, 2nd Embodiment of the thin-film transistor manufactured using the composition for organic semiconductors of this invention is described.
FIG. 4: is a schematic sectional drawing which shows 2nd Embodiment of the thin-film transistor manufactured using the composition for organic semiconductors of this invention.

Hereinafter, the thin film transistor of the second embodiment will be described with a focus on differences from the first embodiment, and description of similar matters will be omitted.
The thin film transistor 1 of the second embodiment is the same as the thin film transistor 1 of the first embodiment except that the arrangement positions of the respective electrodes are different.
That is, the thin film transistor 1 illustrated in FIG. 4 is a bottom-gate thin film transistor in which the gate electrode 50 is located on the substrate 10 side from the source electrode 20a and the drain electrode 20b with the gate insulating layer 40 interposed therebetween.

And the organic-semiconductor layer 30 is formed using the composition for organic semiconductors similar to the said 1st Embodiment.
Such a thin film transistor 1 can also be manufactured in substantially the same manner as the thin film transistor 1 of the first embodiment.
Also by the thin film transistor 1 of the second embodiment, the same operation and effect as the thin film transistor 1 of the first embodiment can be obtained.
In addition, the electronic device which forms an organic-semiconductor layer with the composition for organic-semiconductors of this invention is not limited to a thin film transistor, For example, an organic EL element, a photoelectric conversion element, etc. may be sufficient.

(Example)
Next, specific examples of the present invention will be described.
1-1. Preparation of Liquid Material (Organic Semiconductor Layer Composition of the Present Invention) As shown below, liquid material No. 1-28 were prepared respectively.

(Example)
(Liquid material No.1-5)
A fluorene-bithiophene copolymer (F8T2) is added to a solvent containing at least one of the above five materials (cishydrindan, transhydrindan, 1,3-dimethyladamantane, exotetrahydrodicyclopentadiene, and cineol) in an amount of 1 wt%. The liquid material was prepared by dispersing and dissolving at a ratio.

(Comparative example)
(Liquid material No. 6 to 28)
Except for changing the solvent for dispersing and dissolving F8T2 as shown in Table 1, the liquid material Nos. A liquid material was prepared in the same manner as in 1-5.

1-2. Evaluation Each liquid material was left in a room temperature environment, and the time until F8T2 was precipitated was measured. The results are shown in Tables 1 and 2.

  As shown in Tables 1 and 2, liquid material Nos. 1 to 5 (Examples) are liquid material Nos. 1 to 5 except for the above five materials. Compared with 6-28 (comparative example), it became clear that the precipitation time of F8T2 was as long as 3 months or more, and the stability was high. Thereby, the effect of improving the solubility of the organic solvent containing the above five materials was clarified.

It is a figure which shows schematic structure of the thin-film transistor obtained from the composition for organic semiconductors. It is a figure for demonstrating the manufacturing method of the thin-film transistor shown in FIG. FIG. 3 is a diagram for explaining a manufacturing method of the thin film transistor following FIG. 2. It is a schematic block diagram which shows 2nd Embodiment of a thin-film transistor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Thin film transistor, 10 ... Substrate, 20a ... Source electrode, 20b ... Drain electrode, 30 ... Organic-semiconductor layer, 40 ... Gate insulating layer, 50 ... Gate electrode

Claims (9)

  An organic semiconductor material having a structural unit containing at least one thiophene ring as a repeating unit, and an organic solvent containing at least one of cishydrindan, transhydrindane, 1,3-dimethyladamantane, exotetrahydrodicyclopentadiene, or cineol The composition for organic semiconductors characterized by including these.   The composition for an organic semiconductor according to claim 1, wherein the structural unit includes a π-conjugated structure on the main chain.   The organic semiconductor composition according to claim 2, wherein the π-conjugated structure is a fluorene ring.   The composition for organic semiconductor according to claim 3, wherein the structural unit includes an alkyl chain, and the alkyl chain is bonded to the fluorene ring.   The composition for organic semiconductor according to claim 1, wherein the structural unit includes an alkyl chain.   The organic semiconductor composition according to claim 4 or 5, wherein the alkyl chain has 4 to 20 carbon atoms.   The composition for organic semiconductors according to any one of claims 1 to 6, wherein an average number of the repeating units in the organic semiconductor material is 2 to 500.   The content rate of the said organic-semiconductor material is 0.1-5 wt%, The composition for organic-semiconductors as described in any one of Claims 1-7. A method of manufacturing a transistor comprising a source electrode, a drain electrode, a gate electrode, an organic semiconductor layer, and a gate insulating film that insulates the source electrode and the drain electrode from the gate electrode,
An organic semiconductor material having a structural unit containing at least one thiophene ring as a repeating unit, and an organic solvent containing at least one of cishydrindan, transhydrindane, 1,3-dimethyladamantane, exotetrahydrodicyclopentadiene, or cineol A method for producing a transistor, wherein the organic semiconductor layer is formed by applying a composition for organic semiconductor comprising:

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