JP5256583B2 - Organic semiconductor device and method for manufacturing 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, as a semiconductor material used for the semiconductor transistor, an inorganic semiconductor material such as silicon (Si), gallium arsenide (GaAs), or indium gallium arsenide (InGaAs) has been used. A semiconductor transistor using such an inorganic semiconductor material is also used for a display TFT array substrate of a display element.
On the other hand, as the semiconductor material, an organic semiconductor material made of an organic compound is also known. Such an organic semiconductor material has an advantage that it can be enlarged at a lower cost than the inorganic semiconductor material, can be formed on a flexible plastic substrate, and is stable against mechanical impact. Researches are being actively conducted assuming application to next-generation display devices such as flexible displays represented by electronic paper.

  Here, in the transistor using the organic semiconductor material, a gate electrode 100a, a gate insulating layer 100b that insulates the gate electrode 100a, and an organic semiconductor layer made of the organic semiconductor material are typically illustrated in FIG. 100c and a bottom gate having a source electrode 100d and a drain electrode 100d formed so as to be in contact with the organic semiconductor layer 100c, the gate electrode 100a being disposed on the lower surface side of the organic semiconductor layer 100c There are known a type structure (FIG. 6A), a top gate type structure in which the gate electrode 100a is disposed on the upper surface side of the organic semiconductor layer 100c (FIG. 6B). Yes.

  Here, since the organic semiconductor material generally has a property of being deteriorated by the action of moisture or oxygen in the air, the gate insulating layer used in the organic semiconductor transistor having the top gate structure simply has an insulating function. In addition, it is necessary to provide a protective function for preventing the organic semiconductor material from being exposed to moisture and oxygen in the air.

In this regard, Patent Document 1 discloses an example in which polyimide resin is used for a gate insulating layer as a transistor using the organic semiconductor material.
However, in light of the characteristics of the organic semiconductor material described above, such a gate insulating layer is insufficient in both the insulating function and the protective function, and an organic semiconductor transistor having excellent temporal stability and the like can be obtained. There was a problem that it was difficult.

In addition, since the organic semiconductor material exhibits excellent semiconductor characteristics when deposited in a heated state, when manufacturing a semiconductor transistor using the organic semiconductor material, first, the organic semiconductor material It is necessary to use a method of patterning a layer made of Furthermore, the function of the organic semiconductor material is easily impaired by the action of an organic solvent.
For this reason, when manufacturing a semiconductor transistor using the organic semiconductor material, using photolithography as used in a method for manufacturing a semiconductor element using the inorganic semiconductor material, the photoresist becomes the organic semiconductor material. The organic semiconductor material is dissolved when coated on the layer made of the above, and the performance of the manufactured transistor is impaired.

For such a problem, Patent Document 2 discloses that a coating liquid containing a hydrophilic resin in an aqueous solvent that does not dissolve the organic semiconductor material is applied on the layer made of the organic semiconductor material. By forming a protective layer made of a hydrophilic resin on the layer made of the organic semiconductor material and applying a photoresist on the protective layer, the organic semiconductor material is dissolved and the performance is excellent. A method of forming a transistor is disclosed.
However, such a method is useful in that the organic semiconductor material can be protected from erosion of an organic solvent used when applying the photoresist due to the presence of the protective layer. Compared with the case of manufacturing the used semiconductor transistor, there is a problem that the number of steps for forming the protective layer is increased, so that industrial practicality is lacking.

JP 2003-304014 A JP 2006-58497 A

  The present invention has been made in view of these problems, and is an organic semiconductor element having an organic semiconductor transistor, which can be manufactured with high efficiency, has good temporal stability, and is excellent. An object of the present invention is to provide an organic semiconductor element having characteristics.

  In order to solve the above problems, the present invention provides a substrate, an organic semiconductor layer formed on the substrate and made of an organic semiconductor material, and a source electrode and a drain electrode formed so as to be in contact with the organic semiconductor layer. An organic semiconductor transistor having a gate insulating layer formed on the organic semiconductor layer and an organic semiconductor transistor having a gate electrode formed on the gate insulating layer, wherein the gate insulating layer has an insulating property. An organic semiconductor element comprising a fluororesin is provided.

According to the present invention, since the gate insulating layer is made of a fluorine-based resin, the gate insulating layer has a protective function and an insulating function that prevent the organic semiconductor layer from being exposed to moisture and oxygen in the air. Can be excellent. Therefore, according to the present invention, it is possible to obtain an organic semiconductor element having excellent temporal stability and excellent characteristics.
In addition, according to the present invention, since the fluorine-based resin can be dissolved in a fluorine-based resin having a low surface tension, for example, the gate insulating layer can be manufactured by a printing method. An organic semiconductor transistor can be manufactured with high efficiency.
Therefore, according to the present invention, an organic semiconductor element having an organic semiconductor transistor, which can be manufactured with high efficiency, has good temporal stability, and has excellent characteristics. An element can be obtained.

  In the present invention, the withstand voltage of the fluororesin is preferably in the range of 300 V / μm or less. This is because the use of such a fluororesin makes it possible to make the gate insulating layer more excellent in insulation function, and as a result, the organic semiconductor transistor can be made more excellent in performance.

  In order to solve the above-mentioned problems, the present invention uses a substrate, forms an organic semiconductor layer made of an organic semiconductor material on the substrate, and forms a fluorine-based solvent and an insulating material on the organic semiconductor layer. A gate insulating layer forming step of forming a gate insulating layer in a pattern using a coating liquid for forming a gate insulating layer containing a resin material having a property, and an organic semiconductor layer in a region where the gate insulating layer is not formed There is provided an organic semiconductor element manufacturing method comprising an organic semiconductor transistor forming step including an organic semiconductor layer patterning step for etching.

According to the present invention, when the gate insulating layer is formed on the organic semiconductor layer by using the gate insulating layer forming coating solution using a fluorine-based solvent as the solvent, the organic semiconductor is formed. It is possible to prevent the layer from being eroded by the gate insulating layer forming coating solution. Therefore, according to the present invention, since the gate insulating layer can be formed directly on the organic semiconductor layer without impairing the function of the organic semiconductor layer, an organic semiconductor element can be manufactured with high efficiency. it can.
Moreover, it becomes possible to use a fluorine resin as the resin material by using a coating liquid for forming a gate insulating layer using a fluorine solvent. For this reason, according to this invention, it becomes possible to form the gate insulating layer excellent in the protection function and insulation function of an organic-semiconductor layer by using a fluorine resin as said resin material.
For this reason, according to the present invention, an organic semiconductor element having an organic semiconductor transistor, which has good temporal stability and excellent characteristics, can be produced with high efficiency.

  In the present invention, the resin material is preferably a fluororesin. This is because by using a fluorine-based resin as the resin material, a gate insulating layer having an excellent protective function and insulating function for the organic semiconductor layer can be formed.

  In the present invention, it is preferable that the gate insulating layer forming step forms the gate insulating layer by a printing method. This is because a patterned gate insulating layer can be directly formed on the organic semiconductor layer, so that an organic semiconductor element can be manufactured with higher efficiency.

  Furthermore, in the present invention, the printing method is preferably a screen printing method. This is because the coating liquid for forming a gate insulating layer used in the present invention has a low surface tension due to the use of a fluorinated solvent, and thus can be suitably used for a screen printing method.

  INDUSTRIAL APPLICABILITY The present invention is an organic semiconductor element having an organic semiconductor transistor, and can produce an organic semiconductor element that can be manufactured with high efficiency, has excellent stability over time, and has excellent characteristics. .

The present invention relates to an organic semiconductor element and a method for manufacturing the organic semiconductor element.
Hereinafter, the organic semiconductor element of the present invention and the method for producing the organic semiconductor element will be described in order.

A. Organic Semiconductor Element First, the organic semiconductor element of the present invention will be described. The organic semiconductor element of the present invention includes a substrate, an organic semiconductor layer formed on the substrate and made of an organic semiconductor material, a source electrode and a drain electrode formed so as to be in contact with the organic semiconductor layer, and the organic semiconductor. An organic semiconductor transistor having a gate insulating layer formed on the layer and a gate electrode formed on the gate insulating layer, wherein the gate insulating layer is made of a fluorine-based resin having an insulating property. It is a feature.

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, the organic semiconductor element 10 of the present invention has a configuration in which a plurality of organic semiconductor transistors 2 are formed on a substrate 1.
Here, the organic semiconductor transistor 2 is formed on the substrate 1, and an organic semiconductor layer 2c made of an organic semiconductor material, and a source electrode 2d and a drain electrode 2e disposed so as to face each other on the organic semiconductor layer 2c. A gate insulating layer 2b formed on the organic semiconductor layer 2c, the source electrode 2d and the drain electrode 2e, and a gate electrode 2a formed on the gate insulating layer 2b.
In such an example, the organic semiconductor element 10 of the present invention is characterized in that the gate insulating layer 2b is made of a fluororesin having an insulating property.

  In FIG. 1, as the organic semiconductor transistor 2, the so-called top gate / top contact in which the source electrode 2d and the drain electrode 2e are formed in contact with the organic semiconductor layer 2c and the gate insulating layer 2b. Although the example of the type is shown, the organic semiconductor transistor 2 used in the present invention is not limited to the top gate / top contact type. For example, the source electrode 2d and the source electrode 2d as shown in FIG. The drain electrode 2e may be of a so-called top gate / bottom contact type formed between the organic semiconductor layer 2c and the substrate 1.

According to the present invention, since the gate insulating layer is made of a fluorine-based resin, the gate insulating layer has a protective function and an insulating function that prevent the organic semiconductor layer from being exposed to moisture and oxygen in the air. Can be excellent. Therefore, according to the present invention, it is possible to obtain an organic semiconductor element having excellent temporal stability and excellent characteristics.
According to the present invention, since the fluororesin can be dissolved in a fluororesin having a low surface tension, the gate insulating layer can be manufactured with high efficiency when manufacturing the organic semiconductor transistor. Can do. For this reason, according to this invention, it becomes possible to manufacture the said organic-semiconductor transistor with high efficiency.
Therefore, according to the present invention, an organic semiconductor element having an organic semiconductor transistor, which can be manufactured with high efficiency, has good stability over time, and has excellent characteristics. Can be obtained.

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, an organic semiconductor layer made of an organic semiconductor material, a source electrode and a drain electrode formed so as to be in contact with the organic semiconductor layer, and the above A gate insulating layer formed on the organic semiconductor layer and a gate electrode formed on the gate insulating layer.
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 fluorine-based resin having insulating properties, and the gate electrode insulating function and protection to prevent the organic semiconductor layer described later from being exposed to moisture and oxygen in the air. It has a function (hereinafter, simply referred to as “protection function”).
Here, in the present invention, since the gate insulating layer is made of a fluorine-based resin, a gate insulating layer excellent in the insulating function and the protective function can be formed. Thus, an organic semiconductor element having the above characteristics can be obtained.
Hereinafter, such a gate insulating layer will be described in detail.

  The fluororesin used for the gate insulating layer in the present invention is not particularly limited as long as it can form a gate insulating layer having a desired insulating function and protective function, and the production of the organic semiconductor element of the present invention is not limited. Depending on the method or the like, a fluorine resin having desired properties can be used as appropriate. Among them, the fluororesin used in the present invention preferably has a withstand voltage of 300 V / μm or less, particularly preferably 230 V / μm or less, and more preferably in the range of 150 V / μm to 200 V / μm. It is preferable that This is because by using such a fluorine-based resin, the gate insulating layer can be made more excellent in the insulating function, and as a result, 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.
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: 13% by mass) in which a fluororesin to be evaluated for withstand voltage is dissolved in a solvent, the coating liquid is pattern-coated on the substrate 20 by a screen printing method, and an insulating layer is formed. 22 is formed. At this time, the screen plate pattern is designed to be 1.2 mm × 1.2 mm so that the insulating layer 22 covers the lower electrode 21, and printing is performed with alignment aligned (FIG. 3B). The screen plate is 500 mesh and the emulsion is 3 μm, and the screen printer is an apparatus manufactured by Microtech. Further, the printing conditions are a printing pressure of 0.2 MPa, a clearance of 2.1 mm, and a squeegee speed of 100 mm / sec.
3) The insulating layer 22 is dried on a hot plate at 100 ° C. for 30 minutes.
4) A metal mask having an opening of 1 mm × 1 mm is disposed on the insulating layer 22, and an upper film 23 is formed by 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 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).

Further, the fluororesin used in the present invention preferably has a dielectric constant (60 Hz to 1 MHz room temperature) of 3.0 or less, particularly preferably within a range of 2.0 to 2.5.
Here, the said dielectric constant shall show the value measured according to JISK6911.

Further, the fluororesin used in the present invention preferably has a volume resistivity of 1 × 10 ¹⁵ Ω · cm or more, and more preferably 1 × 10 ¹⁷ Ω · cm or more.
Here, the said dielectric constant shall show the value measured according to JISK6911.

Such a fluororesin may be a fluoroethylene resin, or may be a fluororesin other than a fluoroethylene resin such as polyvinylidene fluoride (PVDF) and polyvinyl fluoride (PVD). good. Among these, in the present invention, it is preferable to use a fluoroethylene resin as the fluorine resin. This is because by using a fluoroethylene resin, the gate insulating layer used in the present invention can be made more excellent in protective function.
Moreover, since fluoroethylene resin is excellent in solvent resistance, for example, even when the organic semiconductor element of the present invention is used in an electrophoretic display, it has an advantage that the protective function of the organic semiconductor layer described later can be maintained. It is.
Furthermore, since fluoroethylene resin is excellent in ozone resistance, for example, when manufacturing the organic semiconductor element of the present invention, the organic semiconductor layer described later is patterned by vacuum ultraviolet light using the gate insulating layer as a mask. This is because there is an advantage that it is possible to use the method.

The fluoroethylene resin may be a polymer of fluoroethylene, or a copolymer of fluoroethylene and ethylene.
The fluoroethylene may be any one having 1 to 4 fluorine atoms.
Furthermore, the fluoroethylene used in the present invention may have an alkyl group such as a methyl group or a substituent such as an alkoxy group in addition to fluorine.

Specific examples of such a fluoroethylene resin include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), Examples thereof include tetrafluoroethylene-ethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), and chlorotrifluoroethylene-ethylene copolymer (ECTFE).
Among these, the fluoroethylene resin used in the present invention is preferably polytetrafluoroethylene (PTFE). This is because the use of polytetrafluoroethylene makes it possible to form a gate insulating layer that is superior in the protective function.

  In addition, the fluororesin used for this invention may be only 1 type, or 2 or more types may be sufficient as it.

  Further, the gate insulating layer used in the present invention may contain other materials in addition to the fluorine resin. Such other materials are not particularly limited as long as they do not impair the insulating function and the protective function, and materials having an arbitrary function may be used depending on the use of the organic semiconductor element of the present invention. Can do.

  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 insulating function and protective function can be imparted to the gate insulating layer, depending on the type of the fluororesin. . 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.

Moreover, as an aspect in which the gate insulating layer in the present invention is formed on the organic semiconductor layer described later, the organic semiconductor layer and the gate insulating layer are stacked at least in a region where a source electrode and a drain electrode described later are formed. There is no particular limitation as long as it is formed as described above. Therefore, the gate insulating layer used in the present invention may have a plan view area larger or smaller than a plan view area of an organic semiconductor layer described later. Furthermore, the gate insulating layer used in the present invention may have the same planar view area as that of an organic semiconductor layer described later.
Here, the “planar area” means a planar area when the organic semiconductor transistor used in the present invention is viewed from the right above the substrate.

(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 polypyrroles such as polypyrrole, poly (N-substituted pyrrole), poly (3-substituted pyrrole), and poly (3,4-disubstituted pyrrole). , Polythiophene, poly (3-substituted thiophene), poly (3,4-disubstituted thiophene), polythiophenes such as polybenzothiophene, polyisothianaphthenes such as polyisothianaphthene, and polychess such as polychenylene vinylene Nylene vinylenes, poly (p-phenylene vinylenes) such as poly (p-phenylene vinylene), polyanilines such as polyaniline and poly (N-substituted aniline), polyacetylenes such as polyacetylene, polyazulenes such as polydiacetylene and polyazulene High molecular organic semiconductor materials such as Of these, pentacene or polythiophenes can be preferably used in the present invention.

  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.

  In the present invention, the organic semiconductor layer is formed as long as it is formed so as to be laminated with the gate insulating layer in a region where a source electrode and a drain electrode described later are formed. It is not particularly limited.

(3) Source and drain electrodes Next, the source and drain electrodes used in the present invention will be described. The source electrode and the drain electrode used in the present invention are formed so as to be in contact with the organic semiconductor layer.

In the present invention, the source electrode and the drain electrode are not particularly limited as long as the source electrode and the drain electrode are formed so as to face each other with a predetermined interval on the organic semiconductor layer. .
As such a mode, for example, as illustrated in FIG. 1 above, the source electrode and the drain electrode are formed between the organic semiconductor layer and the gate insulating layer, and illustrated in FIG. 2 above, for example. An example in which the source electrode and the drain electrode are formed between the substrate described later and the organic semiconductor layer can be given. In the present invention, any of the above-described embodiments can be suitably used as an embodiment in which the source electrode and the drain electrode are formed.
Here, when the source electrode and the drain electrode are formed between the organic semiconductor layer and the gate insulating layer, the organic semiconductor transistor used in the present invention has a top gate / top contact type structure. .
On the other hand, when the source electrode and the drain electrode are formed between the substrate described later and the organic semiconductor layer, the organic semiconductor transistor used in the present invention has a top gate / bottom contact type structure.

  Note that the source electrode and the drain electrode used in the present invention are generally the same as those used in an organic semiconductor transistor, and thus detailed description thereof is omitted here.

(4) Gate electrode Next, the gate electrode used for this invention is demonstrated. The gate electrode used in the present invention is formed on the gate insulating layer.
Here, since the gate electrode used in the present invention is generally the same as that used in an organic semiconductor transistor, a detailed description thereof is omitted here.

(5) Organic semiconductor transistor The organic semiconductor transistor used in the present invention is a so-called top because the gate insulating layer, the organic semiconductor layer, the source electrode, the drain electrode, and the gate electrode are arranged in the above-described manner. It has a gate type structure.
The structure of the organic semiconductor transistor used in the present invention is not particularly limited as long as it is a top gate type structure, and may be a top gate / top contact type structure, or a top gate / bottom contact type. It may be a structure.

  In addition, the organic semiconductor transistor used in the present invention may have other configurations in addition to the gate insulating layer, the organic semiconductor layer, the source electrode, the drain electrode, and the gate electrode. As such other configurations, those having an arbitrary function can be used according to the use of the organic semiconductor element of the present invention. Among these, examples of the other configuration that can be suitably used in the present invention include the gate insulating layer and a passivation layer formed on the gate. As such a passivation layer, what consists of fluororesin, PVA, PVP, etc. can be used, for example.

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 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 As an application of the organic semiconductor element of the present invention, for example, it can be used 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, the manufacturing method described in the section of “B. Manufacturing method of organic semiconductor element” described later can be used.

B. Next, a method for manufacturing an organic semiconductor element of the present invention will be described. The organic semiconductor element manufacturing method of the present invention uses a substrate, an organic semiconductor layer forming step of forming an organic semiconductor layer made of an organic semiconductor material on the substrate, and a fluorine-based solvent and an insulating property on the organic semiconductor layer. A gate insulating layer forming step of forming a gate insulating layer in a pattern using a coating liquid for forming a gate insulating layer containing a resin material, and etching the organic semiconductor layer in a portion where the gate insulating layer is not formed And an organic semiconductor transistor patterning step, and an organic semiconductor transistor formation step.

  Such a method for producing an organic semiconductor element of the present invention will be described with reference to the drawings. FIG. 4 is a schematic view showing an example of a method for producing an organic semiconductor element of the present invention. As illustrated in FIG. 4, the organic semiconductor element manufacturing method of the present invention uses a substrate 1 (FIG. 4A), and forms an organic semiconductor layer 2 c ′ made of an organic semiconductor material on the substrate 1. The semiconductor layer forming step (FIG. 4B), the gate insulating layer forming coating liquid containing a fluorine-based solvent and a resin material having an insulating property on the organic semiconductor layer 2c ′ is used to form a gate in a pattern. A gate insulating layer forming step for forming the insulating layer 2b (FIG. 4C), and an organic semiconductor layer patterning step for etching the organic semiconductor layer 2c ′ in a portion where the gate insulating layer 2b is not formed (FIG. 4). (D)), and an organic semiconductor transistor forming step.

According to the present invention, when the gate insulating layer is formed on the organic semiconductor layer by using the gate insulating layer forming coating solution using a fluorine-based solvent as the solvent, the organic semiconductor is formed. It is possible to prevent the layer from being eroded by the gate insulating layer forming coating solution. Therefore, according to the present invention, since the gate insulating layer can be formed directly on the organic semiconductor layer without impairing the function of the organic semiconductor layer, an organic semiconductor element can be manufactured with high efficiency. it can.
Moreover, it becomes possible to use a fluorine resin as the resin material by using a coating liquid for forming a gate insulating layer using a fluorine solvent. For this reason, according to this invention, it becomes possible to form the gate insulating layer excellent in the protection function and insulation function of an organic-semiconductor layer by using a fluorine resin as said resin material.
For this reason, according to the present invention, an organic semiconductor element having an organic semiconductor transistor, which has good temporal stability and excellent characteristics, can be produced with high efficiency.

The method for producing an organic semiconductor element of the present invention includes at least the organic semiconductor transistor formation step, and may include other steps as necessary.
Hereinafter, each process which comprises the manufacturing method of the organic-semiconductor element of this invention is demonstrated in order.

1. Organic Semiconductor Transistor Forming Step First, the organic semiconductor transistor forming step used in the present invention will be described. This step uses a substrate and forms an organic semiconductor layer made of an organic semiconductor material on the substrate, and a gate insulation containing a fluorine-based solvent and an insulating resin material on the organic semiconductor layer. Using a layer forming coating solution, a gate insulating layer forming step of forming a gate insulating layer in a pattern, an organic semiconductor layer patterning step of etching the organic semiconductor layer in a portion where the gate insulating layer is not formed, It is what has.
Hereinafter, each process used for such an organic semiconductor transistor formation process is demonstrated in order.

(1) Gate Insulating Layer Forming Step First, the gate insulating layer forming step used in this step will be described. This step uses a coating liquid for forming a gate insulating layer containing a fluorine-based solvent and a resin material having insulating properties, and forms a patterned gate insulating material on the organic semiconductor layer formed by the organic semiconductor layer forming step described later. It is a process of forming a layer.

a. First, the gate insulating layer forming coating solution used in this step will be described. The coating liquid for forming a gate insulating layer used in this step contains at least a fluorine-based solvent and a resin material having insulating properties, and may contain other materials as necessary. is there.

  The fluorine solvent used in the gate insulating layer forming coating solution is not particularly limited as long as it does not attack the organic semiconductor layer formed in the organic semiconductor layer forming step described later. In particular, in the present invention, it is preferable to use a perfluoro solvent which is a solvent in which all hydrogen atoms of hydrocarbons such as alkane and alkene are substituted with fluorine.

  Examples of such perfluoro solvents include perfluoromethylcyclohexane, perfluoro-1,3-dimethylcyclohexane, perfluoro-2-methyl-2-pentene, perfluorodecalin, 1,1,1,2, 2,3,3,4,4,5,5,6,6-tridecafluoro-8-iodooctane, 3,3,4,4,5,5,6,6,7,7,8,8 , 8-tridecafluoro-1-octene, 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluoro-1-octanol and the like. .

  Moreover, the fluorine-type solvent used for this process may consist of a single fluorine-type solvent, and may be the mixed solvent in which the some fluorine-type solvent was mixed.

As a resin material having an insulating property used for the gate insulating layer forming coating solution, it is possible to give a desired insulating function and protective function to the gate insulating layer formed by this step, and There is no particular limitation as long as it can be dissolved in the fluorine-based solvent at a desired concentration. In particular, in this step, it is preferable to use a fluorine-based resin as the resin material. This is because the gate insulating layer formed by this process can have an excellent insulating function.
In addition, since fluorine-based resin is excellent in durability such as solvent resistance and ozone resistance, by using such fluorine-based resin, the gate insulating layer formed in this step serves as a protective function for the organic semiconductor layer. This is because it can be made excellent.
Furthermore, it is because a fluorine resin is easily soluble in the fluorine solvent used in this step.

  The fluororesin used in this step is not particularly limited as long as a gate insulating layer having a desired insulating function and protective function can be formed by this step. Such a fluorine-based resin is the same as that described in the above section “A. Organic semiconductor element”, and thus description thereof is omitted here.

  The content of the insulating resin material in the gate insulating layer forming coating solution is determined according to the method for forming the gate insulating layer in this step, etc. There is no particular limitation as long as the solution viscosity, surface tension, and the like are within the desired ranges. Especially in this process, it is preferable that the resin material content in the said coating liquid for gate insulating layer formation exists in the range of 5 mass%-15 mass%.

The gate insulating layer forming coating solution used in this step may contain other materials in addition to the fluorine-based solvent and the resin material having the insulating properties. Such other materials are particularly limited as long as a desired function can be imparted to the gate insulating layer formed in this step, depending on the use of the organic semiconductor element manufactured according to the present invention. is not.
Here, since the other materials used in this step are the same as those described above in “A. Organic semiconductor element”, description thereof is omitted here.

b. Method for Forming Gate Insulating Layer Next, a method for forming a gate insulating layer using the above-mentioned coating liquid for forming a gate insulating layer in this step will be described. In this step, the method for forming the gate insulating layer is not particularly limited as long as the gate insulating layer can be formed in a desired pattern using the gate insulating layer forming coating solution. As such a method, a printing method is used to print the gate insulating layer forming coating solution in a pattern on the organic semiconductor layer (first method), and the gate insulating layer forming coating. A method (second method) in which a liquid is applied to the entire surface of the organic semiconductor layer to form an unpatterned gate insulating layer, and then the gate insulating layer is patterned by a lithography method or the like (second method). Can do.
In this step, any of the first method and the second method can be suitably used, but it is preferable to use the first method. The second method requires two steps of forming a patterned gate insulating layer: a step of forming an unpatterned gate insulating layer and a step of patterning the gate insulating layer. On the other hand, the first method can form a gate insulating layer that is directly patterned in one step, so that this step can be simplified.

  The printing method used in the first method is not particularly limited as long as it is a method capable of printing the gate insulating layer forming coating solution in a desired pattern. Examples of such printing methods include an inkjet method, a screen printing method, a pad printing method, a flexographic printing method, a microcontact printing method, a gravure printing method, an offset printing method, and a gravure / offset printing method. In particular, it is preferable to use a screen printing method in this step. The coating liquid for forming the gate insulating layer used in this step can have a low surface tension because a fluorine-based solvent is used, and is therefore suitable for high-definition pattern coating by the screen printing method. This is because it can be used.

(2) Organic semiconductor layer formation process Next, the organic semiconductor layer formation process used for this process is demonstrated. This step is a step of forming an organic semiconductor layer made of an organic semiconductor material on the substrate using a substrate.
Hereinafter, such an organic semiconductor layer forming step will be described.

In this step, a method for forming an organic semiconductor layer on the substrate may be a method capable of forming an organic semiconductor layer having a desired thickness on the substrate in accordance with the type of the organic semiconductor material used in the step. There is no particular limitation. 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 on the substrate 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. .
On the other hand, when the organic semiconductor material is insoluble in a solvent, for example, a method of forming an organic semiconductor layer on the substrate by a dry process such as a vacuum evaporation method can be exemplified.

  The organic semiconductor material used in this step is particularly limited as long as it can impart desired semiconductor characteristics to the organic semiconductor layer formed by this step, depending on the use of the organic semiconductor element produced by the present invention. Is not to be done. Such an organic semiconductor material is the same as that described in the above section “A. Organic semiconductor element”, and thus description thereof is omitted here.

  Further, the substrate used in this step is the same as that described in the above section “A. Organic semiconductor element”, and thus the description thereof is omitted here.

(3) Organic Semiconductor Layer Patterning Step Next, the organic semiconductor layer patterning step used in this step will be described. This step is a step of patterning the organic semiconductor layer by etching the organic semiconductor layer in a portion where the gate insulating layer is not formed.

  In this step, the method for patterning the organic semiconductor layer is not particularly limited as long as it is a method capable of etching the organic semiconductor layer in a portion where the gate insulating layer is not formed. In particular, in the present invention, there is provided a method of etching only the organic semiconductor layer in a portion where the gate insulating layer is not formed by performing an etching process on the entire surface of the organic semiconductor layer using the gate insulating layer as a mask. It is preferable to use it. This is because according to such a method, the organic semiconductor layer can be easily etched and patterned.

As the etching process used in this step, the organic semiconductor layer in a portion where the gate insulating layer is not formed can be etched, and the protective function and insulating function of the gate insulating layer are not impaired. There is no particular limitation as long as it is present. Examples of such a method include a method of dissolving the organic semiconductor layer with a solvent that dissolves the organic semiconductor material that constitutes the organic semiconductor layer and does not dissolve the resin material that constitutes the gate insulating layer. be able to.
In the case where a fluororesin is used as the resin material constituting the gate insulating layer, it is possible to use a method of etching the organic semiconductor layer by irradiating vacuum ultraviolet light as the etching treatment. is there.

(4) Other Steps This step may include steps other than the gate insulating layer forming step, the organic semiconductor layer forming step, and the organic semiconductor layer patterning step. Such other steps are not particularly limited, and any step can be used according to the structure of the organic semiconductor transistor formed by this step. In particular, in this step, a gate electrode forming step for forming a gate electrode and a source / drain electrode forming step for forming a source electrode and a drain electrode are usually used.

  A case where this step includes the gate electrode formation step and the source / drain electrode formation step will be described with reference to the drawings. FIG. 5 is a schematic view showing an example of an aspect in which the present process includes the gate electrode forming process and the source / drain electrode forming process. As exemplified in FIG. 5, this step usually uses a substrate 1 (FIG. 5A), and an organic semiconductor layer formation step of forming an organic semiconductor layer 2 c ′ on the substrate 1 by the method described above ( 5B), a source / drain electrode forming step of forming the source electrode 2d and the drain electrode 2e on the organic semiconductor layer 2c ′ (FIG. 5C), the organic semiconductor layer 2c ′, the source A gate insulating layer forming step of forming a patterned gate insulating layer 2b on the electrode 2d and the drain electrode 2e by the above-described method (FIG. 5D), and the organic semiconductor layer 2c ′ by the above-described method. An organic semiconductor layer patterning step (FIG. 5E) for patterning the same pattern as the gate insulating layer 2b, and a gate electrode forming process for forming the gate electrode 2a on the gate insulating layer 2b (FIG. 5 (f)) and is carried out in a manner to form the organic semiconductor transistor 2 by.

Here, in FIG. 5, the example in which the source / drain electrode forming step is performed after the organic semiconductor layer forming step has been described. However, in this step, the source / drain electrode forming step is changed to the organic semiconductor layer forming step. The aspect implemented before a process may be sufficient.
When the source / drain electrode forming step is performed after the organic semiconductor layer forming step, the organic semiconductor transistor formed by this step has a top gate / top contact type structure.
On the other hand, when the source / drain electrode formation step is performed before the organic semiconductor layer formation step, the organic semiconductor transistor formed in this step has a top gate / bottom contact type structure.

  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.

2. Other Steps The method for producing an organic semiconductor element of the present invention may have other steps in addition to the organic semiconductor transistor forming step. Such other steps are not particularly limited, and may be appropriately selected and used depending on the use of the organic semiconductor element produced according to the present invention. As such other steps, for example, when the organic semiconductor element of the present invention is used as a TFT array substrate for a liquid crystal display device, a pixel electrode is formed so as to be connected to the organic semiconductor transistor. A process etc. can be mentioned.

  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 (source / drain electrode forming step)
First, after placing a metal mask having source / drain electrode-shaped openings on the surface of a glass substrate having a size of 150 mm × 150 mm × 0.7 mm, an Au film having a thickness of 50 nm is deposited to form source / drain electrodes. did. At this time, the degree of vacuum at the time of vapor deposition was 1 × 10 ⁴ Pa, and the vapor deposition rate was about 1 kg / sec. When the formed source electrode and drain electrode were observed with a reflection optical microscope, the distance between the source electrode and the drain electrode (channel length) was 50 μm.

(Organic semiconductor layer formation process)
Next, an organic semiconductor layer made of a thiophene-based organic semiconductor having a thickness of 50 nm was deposited on the entire surface of the substrate on which the source electrode and the drain electrode were formed.

(Gate insulation layer formation process)
Next, a patterned gate insulating layer was formed by a screen printing method using a coating liquid for forming a gate insulating layer in which polytetrafluoroethylene was dissolved in a perfluoro solvent at a solid content of 13% by mass. At this time, a screen plate having a 500 mesh and 3 μm emulsion was used. The screen printer used was an apparatus manufactured by Microtech. The printing conditions were a printing pressure of 0.2 MPa, a clearance of 2.1 mm, and a squeegee speed of 100 mm / sec. Then, it was dried on a hot plate at 100 ° C. for 30 minutes.

(Organic semiconductor layer patterning process)
Next, in order to remove the organic semiconductor layer other than the portion where the gate insulating layer was formed, a toluene solution was spin coated on the entire surface of the substrate on which the gate insulating layer was formed. At this time, the spin coating was held at 1000 rpm for 20 seconds.

(Gate electrode formation process)
Next, a metal mask having a gate electrode-shaped opening was disposed on the surface on which the gate insulating layer was formed, and then a chromium film having a thickness of 50 nm was formed. Next, a 200 nm aluminum film was deposited to form a gate electrode. The degree of vacuum at the time of vapor deposition was 1 × 10 ⁴ Pa, and the vapor deposition rate was about 1 kg / sec.

  Through the above process, an organic semiconductor element having an organic semiconductor transistor was produced.

(Evaluation)
As a result of measuring the transistor characteristics of the organic semiconductor transistor of the produced organic semiconductor element, it was found that it was driven as a transistor. At this time, the ON current of the organic semiconductor transistor was 1 × 10 ⁻³ A, and the OFF current was 1 × 10 ⁻¹⁰ A. Moreover, as a result of measuring withstand voltage, it was confirmed that 200V was hold | maintained.

(2) Comparative example (source / drain electrode forming step)
First, after placing a metal mask having source / drain electrode-shaped openings on the surface of a glass substrate having a size of 150 mm × 150 mm × 0.7 mm, an Au film having a thickness of 50 nm is deposited to form source / drain electrodes. did. At this time, the degree of vacuum at the time of vapor deposition was 1 × 10 ⁴ Pa, and the vapor deposition rate was about 1 kg / sec. When the formed source electrode and drain electrode were observed with a reflection optical microscope, the distance between the source electrode and the drain electrode (channel length) was 50 μm.

(Organic semiconductor layer formation process)
Next, an organic semiconductor layer made of a thiophene-based organic semiconductor having a thickness of 50 nm was deposited on the entire surface of the substrate on which the source electrode and the drain electrode were formed.

(Gate insulation layer formation process)
Next, a photoresist (acrylic negative resist) was spin-coated as a gate insulating layer. The spin coating at this time was held at 800 rpm for 10 seconds. Thereafter, the substrate was dried at 80 ° C. for 3 minutes and then subjected to pattern exposure at 350 mJ / cm ² .
Next, a development process was performed to remove portions other than the gate electrode, and then the film was dried in an oven at 200 ° C. for 30 minutes.

(Gate electrode formation process)
Next, a metal mask having a gate electrode-shaped opening was disposed on the surface on which the gate insulating layer was formed, and then a chromium film having a thickness of 50 nm was formed. Next, a 200 nm aluminum film was deposited to form a gate electrode. The degree of vacuum at the time of vapor deposition was 1 × 10 ⁴ Pa, and the vapor deposition rate was about 1 kg / sec.

(Evaluation)
As a result of measuring the transistor characteristics of the organic semiconductor transistor of the produced organic semiconductor element, it was found that it was driven as a transistor. At this time, the ON current of the organic semiconductor transistor was 6 × 10 ⁻⁴ A, and the OFF current was 8.4 × 10 ⁻⁹ A. Moreover, as a result of measuring withstand voltage, it was confirmed that 200V was hold | maintained.

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 fluororesin used for this invention. It is the schematic which shows an example of the manufacturing method of the organic-semiconductor element of this invention. It is the schematic which shows the other example of the manufacturing method of the organic-semiconductor element 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, 2 '... Organic semiconductor transistor 2a ... Gate electrode 2b ... Gate insulating layer 2c, 2c' ... Organic semiconductor layer 2d ... Source electrode 2e ... Drain electrode 2f ... Gate insulating layer 10, 10 '... Organic semiconductor element

Claims (5)

An organic semiconductor layer forming step of forming an organic semiconductor layer made of an organic semiconductor material on the substrate using a substrate;
On the organic semiconductor layer, a gate insulating layer forming step of forming a gate insulating layer in a pattern using a coating liquid for forming a gate insulating layer containing a fluorine-based solvent and a resin material having an insulating property; and
The gate insulating layer is formed by a method of dissolving the organic semiconductor material constituting the organic semiconductor layer and dissolving the organic semiconductor layer with a solvent that does not dissolve the resin material constituting the gate insulating layer. A method for producing an organic semiconductor element, comprising: an organic semiconductor layer patterning step for etching an organic semiconductor layer at a portion that is not formed. An organic semiconductor layer forming step of forming an organic semiconductor layer made of an organic semiconductor material on the substrate using a substrate;
A source / drain electrode forming step of forming a source electrode and a drain electrode on the organic semiconductor layer;
Forming a gate insulating layer in a pattern on the organic semiconductor layer, the source electrode, and the drain electrode using a coating liquid for forming a gate insulating layer containing a fluorine-based solvent and a resin material having an insulating property; An insulating layer forming step;
  An organic semiconductor transistor forming step including an organic semiconductor layer patterning step of etching an organic semiconductor layer in a portion where the gate insulating layer is not formed. The method for producing an organic semiconductor element according to claim 1, wherein the resin material is a fluororesin. The gate insulating layer forming step, characterized in that the printing method is to form the gate insulating layer, a method of manufacturing an organic semiconductor device according to any one of claims 1 to 3. The method for producing an organic semiconductor element according to claim 4 , wherein the printing method is a screen printing method.

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