JP5200377B2 - Organic semiconductor device - Google Patents

Description

  The present invention relates to an organic semiconductor element using an organic semiconductor transistor.

  In recent years, semiconductor transistors typified by TFTs tend to expand their applications with the development of display devices. Such a semiconductor transistor functions as a switching element when electrodes are connected via a semiconductor material. Conventionally, inorganic semiconductor materials such as silicon (Si), gallium arsenide (GaAs), and indium gallium arsenide (InGaAs) have been used as semiconductor materials used in the semiconductor transistors. In recent years, a semiconductor transistor using such an inorganic semiconductor material is also used for a TFT array substrate for a display of a liquid crystal display element that has been widely spread.

  On the other hand, as the semiconductor material, an organic semiconductor material made of an organic compound is also known. As illustrated in FIG. 9, the transistor 100 using the organic semiconductor material generally includes a gate electrode 100a, a gate insulating layer 100b that insulates the gate electrode 100a, and an organic semiconductor layer 100c made of the organic semiconductor material. A bottom gate structure having a source electrode 100d and a drain electrode 100e formed so as to be in contact with the organic semiconductor layer 100c, wherein the gate electrode 100a is disposed on the lower surface side of the organic semiconductor layer 100c. (FIG. 9A), and a top gate structure in which the gate electrode 100a is disposed on the upper surface side of the organic semiconductor layer 100c (FIG. 9B) are known.

  A transistor using such an organic semiconductor material is cheaper and can have a larger area than the inorganic semiconductor material, can be formed on a flexible plastic substrate, and is stable against mechanical shock. Because of its advantages, research is actively conducted assuming application to next-generation display devices such as flexible displays typified by electronic paper.

  However, as illustrated in FIG. 9, a transistor using an organic semiconductor material is generally formed so that the organic semiconductor layer and the gate insulating layer are in contact with each other. For this reason, it is known that the semiconductor characteristics of the organic semiconductor layer are affected by the material constituting the gate insulating layer, and the transistor performance changes. For example, Patent Document 1 discloses a transistor using a gate insulating layer made of polyimide, but an organic semiconductor transistor using a gate insulating layer made of such a material has a threshold voltage of a gate voltage. However, there was a problem that was not stable.

  In general, a transistor using the organic semiconductor material has a feature that a driving voltage is higher than that of a transistor using a conventional inorganic semiconductor material. For this reason, as a material used for the gate insulating layer, it is necessary to use a material having a higher withstand voltage as compared with a transistor using a conventional inorganic semiconductor material. Therefore, the material used for the gate insulating layer is required to have a predetermined withstand voltage in addition to not impairing the transistor characteristics by acting on the organic semiconductor layer as described above. However, conventionally, there has been no material for a gate insulating layer that satisfies these characteristics.

  For these reasons, conventionally, it has been difficult to obtain a transistor using an organic semiconductor material, in which the transistor characteristics are not impaired by the gate insulating layer.

JP 2003-304014 A

  The present invention has been made in view of such problems, and an object of the present invention is to provide an organic semiconductor element having an organic semiconductor transistor, which is excellent in the stability of the threshold voltage of the gate voltage. It is what.

  In order to solve the above problems, the present invention provides an organic semiconductor transistor comprising a substrate, an organic semiconductor layer formed on the substrate and made of an organic semiconductor material, and a gate insulating layer formed in contact with the organic semiconductor layer. The organic semiconductor element is characterized in that the gate insulating layer is made of a cured product of cardo type resin represented by the following formula (I).

In the above formula (I), R ¹ and R ² each independently represent a side chain having a polymerizable functional group.

  According to the present invention, the organic semiconductor transistor can be made excellent in the stability of the threshold voltage of the gate voltage because the gate insulating layer is made of a cured product of cardo type resin represented by the above formula (I). For this reason, according to this invention, it is an organic semiconductor element which has an organic semiconductor transistor, Comprising: The organic semiconductor element excellent in the stability of the threshold voltage of a gate voltage can be obtained.

  In the present invention, the organic semiconductor transistor preferably has a bottom gate type structure. This is because the organic semiconductor transistor has a bottom-gate structure, which makes it easy to manufacture the organic semiconductor element of the present invention.

  The present invention provides an organic semiconductor element having an organic semiconductor transistor, which can provide an organic semiconductor element having excellent gate voltage threshold voltage stability.

  Hereinafter, the organic semiconductor element of the present invention will be described.

  An organic semiconductor element of the present invention includes a substrate, and an organic semiconductor transistor including an organic semiconductor layer formed on the substrate and made of an organic semiconductor material, and a gate insulating layer formed so as to be in contact with the organic semiconductor layer. The gate insulating layer is made of a cured product of a cardo type resin represented by the above formula (I).

Such an organic semiconductor element of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing an example of the organic semiconductor element of the present invention. As illustrated in FIG. 1, an organic semiconductor element 10 of the present invention includes a substrate 1 and an organic semiconductor transistor 2 formed on the substrate 1.
In such an example, the organic semiconductor transistor 2 is in contact with the gate electrode 2a formed on the substrate 1, the gate insulating layer 2b formed on the gate electrode 2a, and the gate insulating layer 2b. The organic semiconductor layer 2c is formed and made of an organic semiconductor material, and the source electrode 2d and the drain electrode 2e are formed so as to face each other on the organic semiconductor layer 2c.
Here, the organic semiconductor element 10 of the present invention is characterized in that the gate insulating layer 2b is made of a cured product of cardo type resin represented by the above formula (I).

  1 shows an example of a bottom gate structure in which the gate electrode 2a is disposed closer to the substrate 1 than the organic semiconductor layer 2c as the organic semiconductor transistor 2. However, the organic semiconductor transistor 2 used in the present invention is not limited to the one having the bottom gate structure. For example, the organic semiconductor layer 2c illustrated in FIG. 2 is more than the gate electrode 2a. It may have a top gate structure arranged on the substrate 1 side.

According to the present invention, the organic semiconductor transistor can be made excellent in the stability of the threshold voltage of the gate voltage because the gate insulating layer is made of a cured product of cardo type resin represented by the above formula (I).
For this reason, according to this invention, it is an organic semiconductor element which has an organic semiconductor transistor, Comprising: The organic semiconductor element excellent in the stability of the threshold voltage of a gate voltage can be obtained.

  Further, since the cardo type resin represented by the above formula (I) has an excellent withstand voltage, the gate insulating layer is made of such a cured product of the cardo resin, so that the gate insulating layer used in the present invention has an withstand voltage As a result, the transistor characteristics of the organic semiconductor transistor used in the present invention can be improved.

  Furthermore, in the present invention, since the cardo type resin represented by the above formula (I) is used as the material constituting the gate insulating layer, there is an advantage that the gate insulating layer can be excellent in flatness. Have.

The organic semiconductor element of the present invention includes at least the substrate and the organic semiconductor transistor.
Hereafter, each structure used for the organic-semiconductor element of this invention is demonstrated in order.

1. Organic Semiconductor Transistor First, the organic semiconductor transistor used in the present invention will be described. The organic semiconductor transistor used in the present invention is formed on a substrate to be described later, and is formed so as to be in contact with the organic semiconductor layer made of an organic semiconductor material and the organic semiconductor layer, and is represented by the above formula (I). And a gate insulating layer made of a cured product of cardo type resin.
Hereinafter, such an organic semiconductor transistor will be described.

(1) Gate Insulating Layer First, the gate insulating layer used in the present invention will be described. The gate insulating layer used in the present invention is made of a cured product of cardo type resin represented by the above formula (I). In the present invention, an organic semiconductor element excellent in the stability of the threshold voltage of the gate voltage can be obtained by using a gate insulating layer made of such a cured product of cardo type resin.

  The cardo type resin used in the present invention is not particularly limited as long as it is represented by the above formula (I) and can form a gate insulating layer having a predetermined withstand voltage. As such a cardo type resin, those having desired properties can be used according to the method for producing an organic semiconductor element of the present invention. Among them, the cardo type resin used in the present invention preferably has a dielectric breakdown strength in the range of 200 V / μm to 300 V / μm, and particularly preferably in the range of 250 V / μm to 300 V / μm. This is because by using such a cardo type resin, the gate insulating layer can be made more excellent in the insulating function, so that the organic semiconductor transistor can be made more excellent in performance.

Here, the said withstand voltage can be measured by the method as shown in FIG. 3, for example. That is,
1) A patterned ITO electrode 21 (1 mm × 1 mm, thickness 1200 mm: hereinafter, the ITO electrode 21 may be referred to as a lower electrode) is formed on the surface of a glass substrate 20 having a size of 100 mm × 100 mm × 0.7 mm. (FIG. 3A).
2) Using a coating liquid (solid content: 20% by mass) in which a cardo type resin to be evaluated for withstand voltage is dissolved in a solvent, the coating liquid is applied onto the substrate 20 by spin coating, and the insulating layer 22 (FIG. 3B). At this time, the coating condition is 800 rpm / 10 sec.
3) The insulating layer 22 is pre-baked on a hot plate at 120 ° C. for 2 minutes. Acetone is used for a portion of the ITO electrode 21 to expose the surface of the electrode and then dried in an oven at 230 ° C. for 30 minutes. 4) A metal mask having an opening of 1 mm × 1 mm is disposed on the insulating layer 22. The upper electrode 23 is formed by vapor-depositing an Au film having a thickness of 50 nm (FIG. 3C). At this time, the degree of vacuum at the time of vapor deposition is 1 × 10 ⁻⁴ Pa, and the vapor deposition rate is about 1 kg / sec.
5) A voltage of 0 V to 300 V is applied between the upper electrode 21 and the lower electrode 23, and the current value I flowing between the upper electrode 21 and the lower electrode 23 is measured. Based on the obtained data, the horizontal axis represents the electric field intensity E (value obtained by dividing the applied voltage V by the film thickness d of the insulating layer 22), and the vertical axis represents the resistance value R of the insulating layer 22 (applied voltage as a current value). Plotted as (divided value). Based on the graph produced in this manner, the electric field strength value E ₀ at which the resistance value R rapidly decreases is defined as the dielectric breakdown strength (withstand voltage).

The cardo type resin used in the present invention is represented by the above formula (I), and R ¹ and R ² in the above formula (I) have a polymerizable functional group, and the present invention The gate insulating layer used in the above is not particularly limited as long as it has a molecular weight that can distribute the cyclic sites in the formula (I) with a predetermined density. In particular, in the present invention, among the cardo resins represented by the above formula (I), cardo resins represented by the following formula (II) can be preferably used.

Here, in the above formula (II), X ¹ and X ² represent a polymerizable functional group. R ¹¹ and R ¹² represent a linking group.

  As the linking group used in the present invention, in the gate insulating layer used in the present invention, the polymerizable functional group is long enough to distribute the cyclic site in the formula (II) with a predetermined abundance density. The group is not particularly limited as long as the group can be connected to the cyclic structure. Of these, hydrocarbon chains are preferably used in the present invention. By using a hydrocarbon chain as the linking group, it is possible to arbitrarily adjust the linking length between the polymerizable functional group and the cyclic structure by appropriately adjusting the number of carbon atoms constituting the hydrocarbon chain. Because it becomes.

When a hydrocarbon chain is used as the linking group, the hydrocarbon chain is not particularly limited as long as it can link the cyclic structure and the polymerizable functional group with a predetermined length. Therefore, the hydrocarbon chain used in the present invention may be a straight chain having no branched chain or a branched chain having a branched chain. Further, it may be a saturated hydrocarbon chain consisting only of a saturated bond, or an unsaturated hydrocarbon chain containing a double bond or a triple bond. Furthermore, the hydrocarbon chain used in the present invention may have an arbitrary functional group bonded thereto.
Among them, the hydrocarbon chain used in the present invention preferably has 1 to 20 carbon atoms, particularly preferably 1 to 10 carbon atoms, and more preferably 1 to 5 carbon atoms. preferable. Here, the number of carbon atoms refers to the number of carbon atoms constituting the main chain of the hydrocarbon chain, and does not include the number of carbon atoms constituting the side chain.

  The cardo type resin used in the present invention includes a photo-curable cardo type resin in which the polymerizable functional group is a photopolymerizable functional group that undergoes a polymerization reaction by light irradiation, and thermal polymerization that causes a polymerization reaction when heated. And thermosetting cardo type resin which is a functional functional group.

  Examples of the photopolymerizable functional group include various polymerizable functional groups that are polymerized by the action of ionizing radiation such as ultraviolet rays and electron beams. Typical examples of such a photopolymerizable functional group include a vinyl group, an acrylate group (a generic term including an acryloyl group, a methacryloyl group, an acryloyloxy group, a methacryloyloxy group), a sulfonyl group, and the like. it can.

  On the other hand, examples of the thermally polymerizable functional group include an epoxy group, an isocyanate group, a carboxyl group, an amino group, and a hydroxy group.

  In the present invention, any of the photocurable cardo resin and the thermosetting cardo resin can be suitably used.

  Specific examples of the photocurable cardo type resin used in the present invention include compounds represented by the following formulas.

  In addition, specific examples of the thermosetting cardo type resin used in the present invention include compounds represented by the following formula.

  The cardo type resin used in the present invention may be only one type or two or more types.

  The gate insulating layer used in the present invention contains a cured product of the cardo type resin described above, but the cured product of the cardo type resin in the present invention is obtained by polymerizing a single cardo type resin. Or a plurality of types of cardo resins may be copolymerized.

  The gate insulating layer used in the present invention may contain other materials in addition to the cured cardo resin. Such other materials are not particularly limited as long as they do not impair the withstand voltage of the gate insulating layer and the characteristics of the organic semiconductor layer described later, depending on the use of the organic semiconductor element of the present invention, etc. A material having an arbitrary function can be used.

  The thickness of the gate insulating layer used in the present invention is not particularly limited as long as it is within a range in which a desired withstand voltage can be imparted to the gate insulating layer according to the type of the cardo type resin. Especially in this invention, it is preferable that it is 100 micrometers or less, It is preferable to exist in the range of 0.1 micrometer-10 micrometers especially, and it is further preferable to exist in the range of 0.3 micrometer-1 micrometer.

(2) Organic Semiconductor Layer Next, the organic semiconductor layer used in the present invention will be described. The organic semiconductor layer used in the present invention is made of an organic semiconductor material.

  The organic semiconductor material used in the present invention is not particularly limited as long as it is a material capable of forming an organic semiconductor layer having desired semiconductor characteristics, depending on the use of the organic semiconductor element of the present invention, etc. In particular, an organic semiconductor material used for an organic semiconductor transistor using an organic semiconductor material can be used. Examples of such organic semiconductor materials include π-electron conjugated aromatic compounds, chain compounds, organic pigments, and organosilicon compounds. More specifically, low molecular organic semiconductor materials such as pentacene and oligothiophene, and polypyrrole, poly (N-substituted pyrrole), poly (3-substituted pyrrole), poly (3,4-disubstituted pyrrole) and the like Polypyrroles, polythiophene, poly (3-substituted thiophene), poly (3,4-disubstituted thiophene), polythiophenes such as polybenzothiophene, polyisothianaphthenes such as polyisothianaphthene, polychenylene vinylene, etc. Polychenylene vinylenes, poly (p-phenylene vinylenes) such as poly (p-phenylene vinylene), polyanilines such as polyaniline and poly (N-substituted aniline), polyacetylenes such as polyacetylene, polydiacetylene, polyazulene and the like Polymer organic semiconductor materials such as polyazulenes Kill. In particular, in the present invention, it is preferable to use the low molecular organic semiconductor material. This is because by using a low molecular organic semiconductor material as the organic semiconductor material, the organic semiconductor element of the present invention can be made more excellent in transistor characteristics.

  Moreover, about the thickness of the organic-semiconductor layer used for this invention, if it is the range which can express the organic-semiconductor layer provided with a desired semiconductor characteristic according to the kind etc. of the said organic-semiconductor material, it will not specifically limit. Especially in this invention, it is preferable that it is 1000 nm or less, It is preferable that it is in the range of 5 nm-300 nm, and it is especially preferable that it is in the range of 20 nm-100 nm.

(3) Organic Semiconductor Transistor The organic semiconductor transistor used in the present invention has at least the gate insulating layer and the organic semiconductor layer. Usually, in addition to the gate insulating layer and the organic semiconductor layer, a gate electrode By using the source electrode and the drain electrode, a function as a transistor is exhibited.

  Here, the structure of the organic semiconductor transistor used in the present invention is not particularly limited as long as the organic semiconductor layer is formed so as to be in contact with the gate insulating layer. A structure can be adopted. Examples of the structure of such an organic semiconductor transistor include a bottom gate type structure and a top gate type structure.

A case where the organic semiconductor transistor used in the present invention has a bottom-gate structure will be described with reference to the drawings. FIG. 4 is a schematic view showing an example in which the organic semiconductor transistor used in the present invention has a bottom gate type structure. As illustrated in FIGS. 4A and 4B, the organic semiconductor transistor 2 used in the present invention has a bottom gate type structure in which the gate electrode 2a is disposed closer to the substrate 1 than the organic semiconductor layer 2c. You may have.
Furthermore, the organic semiconductor transistor 2 used in the present invention may have a bottom gate / top contact type structure in which the source electrode 2d and the drain electrode 2e are disposed on the upper surface of the organic semiconductor layer 2c (FIG. 4A Or a bottom gate / bottom contact type structure in which the source electrode 2d and the drain electrode 2e are disposed on the lower surface of the organic semiconductor layer 2c (FIG. 4B).

Next, the case where the organic semiconductor transistor used in the present invention has a top gate type structure will be described with reference to the drawings. FIG. 5 is a schematic view showing an example in which the organic semiconductor transistor used in the present invention has a top gate structure. As illustrated in FIG. 5, the organic semiconductor transistor 2 used in the present invention may have a top gate type structure in which the organic semiconductor layer 2 c is disposed closer to the substrate 1 than the gate electrode 2 a.
Furthermore, the organic semiconductor transistor 2 used in the present invention may have a top gate / top contact type structure in which the source electrode 2d and the drain electrode 2e are disposed on the upper surface of the organic semiconductor layer 2c (FIG. 5A Or a top gate / bottom contact type structure in which the source electrode 2d and the drain electrode 2e are disposed on the lower surface of the organic semiconductor layer 2c (FIG. 5B).

  Here, as the organic semiconductor transistor used in the present invention, any of those having the above bottom gate structure or the above top gate structure can be preferably used. It is preferable to have a structure. This is because the organic semiconductor transistor has a bottom-gate structure, which makes it easy to manufacture the organic semiconductor element of the present invention.

  As the gate electrode, the source electrode, and the drain electrode used in the present invention, those made of a metal material are usually used. Such a metal material is not particularly limited as long as it has desired conductivity, and a metal material generally used for an electrode of an organic semiconductor transistor can be used. Examples of such metal materials include Ta, Ti, Al, Zr, Cr, Nb, Hf, Mo, Au, Ag, Pt, and a Mo—Ta alloy. Of these, Au or Al is preferably used in the present invention. It is because the performance of the organic semiconductor element manufactured by the present invention can be improved by using such a metal material.

  Moreover, the organic semiconductor transistor used in the present invention may have a passivation layer that prevents the organic semiconductor layer from being exposed to moisture or the like contained in the air. This is because by having such a passivation layer, the organic semiconductor transistor used in the present invention can be reduced in deterioration of the transistor performance over time.

  FIG. 6 is a schematic view showing an example in the case where the organic semiconductor transistor used in the present invention has the passivation layer. As illustrated in FIGS. 6A and 6B, the organic semiconductor transistor 2 used in the present invention may be one in which a passivation layer 2f is formed so as to cover the organic semiconductor layer 2c.

  The material used for the passivation layer used in the present invention is not particularly limited as long as it can prevent the organic semiconductor layer from being exposed to moisture contained in the air to a desired degree. . Examples of such materials include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and tetrafluoroethylene- Examples include fluorine resins such as ethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), and chlorotrifluoroethylene-ethylene copolymer (ECTFE), and water-soluble resins such as PVP and PVA. it can.

  In addition, the organic semiconductor element of this invention has the structure by which the several organic semiconductor transistor is normally arrange | positioned on the board | substrate mentioned later. Here, the aspect in which the plurality of organic semiconductor transistors are arranged on the substrate is not particularly limited, and the organic semiconductor transistors can be arranged in a desired form according to the use of the organic semiconductor element of the present invention.

2. Substrate Next, the substrate used in the present invention will be described. The substrate used in the present invention supports the organic semiconductor transistor.

  As a board | substrate used for this invention, the board | substrate which has arbitrary functions can be used according to the use etc. of the organic-semiconductor element of this invention. Such a substrate may be a rigid substrate having no flexibility such as a glass substrate, or may be a flexible substrate having flexibility such as a film made of a plastic resin. In the present invention, any of such a rigid substrate and a flexible substrate is preferably used, and among them, it is preferable to use a flexible substrate. By using such a flexible substrate, the organic semiconductor element of the present invention can be manufactured by a Roll to Roll process, so that the organic semiconductor element of the present invention can be made highly productive. is there.

  Here, examples of the plastic resin include PET, PEN, PES, PI, PEEK, PC, PPS, and PEI.

  Moreover, the thickness of the substrate used in the present invention is usually preferably 1 mm or less, and particularly preferably in the range of 50 μm to 700 μm.

3. Use of Organic Semiconductor Element The organic semiconductor element of the present invention can be used, for example, as a TFT array substrate of a display device using a TFT method. Examples of such a display device include a liquid crystal display device, an electrophoretic display device, and an organic EL display device.

4). Method for Producing Organic Semiconductor Element The method for producing the organic semiconductor element of the present invention is not particularly limited as long as it is a method capable of producing an organic semiconductor element having the above configuration. As such a manufacturing method, for example, a gate electrode forming step of forming a gate electrode on the substrate using the substrate described above, and a gate insulating layer forming containing the cardo type resin described above on the gate electrode. A gate insulating layer forming step of forming a gate insulating layer by curing the cardo type resin after forming a coating film of the coating liquid for forming the gate insulating layer by applying a coating liquid on the substrate. And an organic semiconductor layer forming step of forming an organic semiconductor layer made of an organic semiconductor material on the gate insulating layer, and a source / drain electrode forming step of forming a source electrode and a drain electrode on the organic semiconductor layer Can be mentioned. According to such a method, an organic semiconductor element having the above-described bottom-gate organic semiconductor transistor can be manufactured.

  As another example of the manufacturing method, a source / drain electrode forming step of forming a source electrode and a drain electrode on the substrate using the substrate described above, and an organic semiconductor material on the source electrode and the drain electrode is formed. An organic semiconductor layer forming step for forming an organic semiconductor layer, and the gate insulating layer forming coating by coating the organic semiconductor layer with the gate insulating layer forming coating liquid containing the cardo type resin described above. A method using a gate insulating layer forming step of forming a gate insulating layer by curing the cardo-type resin after forming a liquid coating film, and a gate electrode forming step of forming a gate electrode on the organic semiconductor layer Can be mentioned. According to such a method, an organic semiconductor element having the above-described organic semiconductor transistor having a top gate structure can be manufactured.

  As the gate insulating layer forming coating solution used in the gate insulating forming step, a solution obtained by dissolving the cardo type resin in a solvent is usually used. The solvent is not particularly limited as long as it can dissolve the cardo resin described above at a desired concentration, and any solvent can be used according to the type of the cardo resin. Examples of such a solvent include methyl ethyl ketone, cyclohexanone, propylene glycol monomethyl ether, propylene glycol monoethyl ether, methyl cellosolve, methyl cellosolve acetate, ethyl cellosolve, ethyl cellosolve acetate, and diethylene glycol dimethyl ether.

  In addition, as a method of applying the gate insulating layer forming coating liquid in the gate insulating layer forming step, for example, spin coating method, die coating method, roll coating method, bar coating method, LB method, dip coating method, Application methods such as spray coating, blade coating, and casting methods, inkjet methods, screen printing methods, pad printing methods, flexographic printing methods, microcontact printing methods, gravure printing methods, offset printing methods, and gravure offsets Examples of the printing method include a printing method.

  Furthermore, in the gate insulating layer forming step, a method for curing the cardo resin may be arbitrarily selected according to the type of polymerizable functional group possessed by the cardo resin. For example, when the photocurable cardo type resin described above is used as the cardo type resin, a method of irradiating light capable of inducing a polymerization reaction of a photopolymerizable functional group may be used as the curing method. When a thermosetting cardo type resin is used as the mold resin, a method of applying heat that can induce a polymerization reaction of the thermopolymerizable functional group may be used as the curing method.

On the other hand, the method for forming the organic semiconductor layer in the organic semiconductor layer forming step is not particularly limited as long as it can form an organic semiconductor layer having a desired thickness according to the type of the organic semiconductor material used. is not. As such a method, for example, when the organic semiconductor material is soluble in a solvent, the organic semiconductor material is dissolved in a solvent to prepare an organic semiconductor layer forming coating solution, A method of coating the organic semiconductor layer forming coating solution can be mentioned. Examples of the coating method in this case include a spin coating method, a die coating method, a roll coating method, a bar coating method, an LB method, a dip coating method, a spray coating method, a blade coating method, and a casting method. it can.
On the other hand, when the said organic-semiconductor material is insoluble in a solvent, the method of forming an organic-semiconductor layer by dry processes, such as a vacuum evaporation method, can be mentioned, for example.

  In the gate electrode formation step and the source / drain electrode formation step, a method of forming the gate electrode, the source electrode, and the drain electrode, respectively, is generally used when forming a semiconductor transistor. The detailed description here is omitted.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  Hereinafter, the present invention will be specifically described with reference to examples.

1. Example (1) Obtaining and Cleaning Substrate As a base, non-alkali glass (# 1737) 25 mm × 25 mm manufactured by Corning was obtained, and washed according to the following procedure.
i) The substrate is immersed in a “Semicoclean” stock solution manufactured by Furuuchi Chemical Co., Ltd., and cleaned for 15 minutes using an ultrasonic cleaner.
ii) Using an ultrasonic cleaner, rinse with pure water for 5 minutes × 3 times.
iii) Using an ultrasonic cleaner, wash in acetone for 15 minutes.
iv) Using an ultrasonic cleaner, wash in 2-propanol for 15 minutes.
v) Place in an oven at 230 ° C. and dry for 30 minutes.

(2) Formation of gate electrode The substrate cleaned in the above-described procedure is cleaned for 5 minutes using a UV ozone cleaner, and then patterned using a mask in a sputtering apparatus (SPF-730, manufactured by Canon Anelva) using Cr as a target. Formed. At this time, the film thickness of Cr was set to 50 nm.

(3) Formation of gate insulating layer Using a substrate on which a gate electrode is formed, a photocurable cardo type resin is formed using a spinner so as to have a film thickness of 1 μm, and then heated on a 120 ° C. hot plate for 2 minutes. A semi-cured layer was formed.
Here, the photocurable cardo type resin is a random product obtained by reacting bis-phenolfluorene-hydroxyacrylate, bis-aniline-fluorene, and pyromellitic acid anhydride at a molar ratio = 1: 4: 5. A copolymer was used.

Next, a photoetching mask drawn so as to shield light other than the portion where the gate insulating layer is formed is placed on the semi-cured layer of the photocurable cardo type resin, and then the ultraviolet ray is applied under the condition of 350 mJ / cm ² . The gate insulating layer was formed by irradiating with and exposing and developing. Then, in order to harden a gate insulating layer completely, it heated for 30 minutes in 230 degreeC oven.

(3) Formation of organic semiconductor layer A liquid crystal organic semiconductor material (5,5 ′ ″-dioctyl-2, 2 ′: 5 ′, 2 ″: 5 ″, 2 is formed on the substrate on which the gate insulating layer is formed. The organic semiconductor layer was formed by patterning '''-quaterthiophene) with a mask using a vapor deposition apparatus (VPC-060) manufactured by ULVAC. At this time, the film thickness of the organic semiconductor layer was set to 50 nm.

(4) Formation of Source Electrode and Drain Electrode A source electrode and a drain electrode were formed on a substrate on which an organic semiconductor layer was formed, using Au as a vapor deposition source with a vapor deposition apparatus (VPC-060) manufactured by ULVAC. At this time, the film thickness of the source electrode and the drain electrode was 50 nm.

  An organic semiconductor element was produced by the method as described above.

2. Comparative Example When forming the gate insulating layer, the organic resin was prepared in the same manner as in Example except that a polyimide-based photocurable resin (CT4160R manufactured by Kyocera Chemical Co., Ltd.) was used instead of the photocurable cardo resin. A semiconductor element was produced.

3. Evaluation Regarding the organic semiconductor elements produced in the examples and comparative examples, the transfer characteristics of the organic semiconductor transistors were measured by scanning in the range of a source-drain voltage of −80 V and a gate voltage of 80 V to −80 V. The results are shown in FIGS. 7 and 8, respectively. (FIG. 7: Example, FIG. 8: Comparative Example)

  As shown in FIGS. 7 and 8, the organic semiconductor element of the example showed stable characteristics when the threshold voltage of the gate voltage was around 0V, but the organic semiconductor element of the comparative example deviated greatly from the threshold voltage of 0V. It was.

It is the schematic which shows an example of the organic-semiconductor element of this invention. It is the schematic which shows the other example of the organic-semiconductor element of this invention. It is the schematic which shows an example of the withstand voltage measuring method of the cardo type resin used for this invention. It is the schematic which shows an example of the organic-semiconductor transistor used for this invention. It is the schematic which shows the other example of the organic-semiconductor transistor used for this invention. It is the schematic which shows the other example of the organic-semiconductor transistor used for this invention. It is a graph which shows the transistor characteristic of the organic-semiconductor element in the Example of this invention. It is a graph which shows the transistor characteristic of the organic-semiconductor element in the comparative example of this invention. It is the schematic which shows an example of a common semiconductor transistor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Organic semiconductor transistor 2a ... Gate electrode 2b ... Gate insulating layer 2c ... Organic semiconductor layer 2d ... Source electrode 2e ... Drain electrode 2f ... Passivation layer 10 ... Organic semiconductor element 100 ... Organic semiconductor transistor 100a ... Gate electrode 100b ... Gate insulating layer 100c ... Organic semiconductor layer 100d ... Source electrode 100e ... Drain electrode

Claims (2)

An organic semiconductor element comprising: a substrate; and an organic semiconductor transistor formed on the substrate and including an organic semiconductor layer made of an organic semiconductor material and a gate insulating layer formed so as to be in contact with the organic semiconductor layer,
The gate insulating layer, Ri Do the cured product of the cardo resin represented by the following formula (I),
An organic semiconductor device, wherein the cured product of the cardo resin is a random copolymer of bis-phenolfluorene-hydroxyacrylate, bis-aniline-fluorene, and pyromellitic acid anhydride .

(In the above formula, R ¹ and R ² each independently represent a side chain having a polymerizable functional group.)   2. The organic semiconductor device according to claim 1, wherein the organic semiconductor transistor has a bottom gate structure.

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