WO2011148707A1

WO2011148707A1 - Process for production of organic semiconductor device

Info

Publication number: WO2011148707A1
Application number: PCT/JP2011/057465
Authority: WO
Inventors: 勝一香村; 恭崇葛本; 繁青森
Original assignee: シャープ株式会社
Priority date: 2010-05-27
Filing date: 2011-03-25
Publication date: 2011-12-01

Abstract

An organic transistor (1) comprises a source electrode (14),an organic semiconductor layer (16), and an injection-improving layer (40) arranged between the source electrode (14) and the organic semiconductor layer (16), and additionally comprises an extraction-improving layer (50) arranged between an drain electrode (15) and the organic semiconductor layer (16), wherein the injection-improving layer (40) and the extraction-improving layer (50) are formed by forming an improving layer comprising the same material as that constitutes the source electrode (14) and the drain electrode (15) on the source electrode (14) and the drain electrode (15) and subsequently modifying the improving layer on the source electrode (14) or the improving layer on the drain electrode (15).

Description

Method for manufacturing organic semiconductor device

The present invention relates to a method for manufacturing an organic semiconductor device using an organic semiconductor material for an organic semiconductor layer of a field effect transistor.

A so-called organic transistor using an organic semiconductor material as a semiconductor layer of a field effect transistor is easier to manufacture on a large-area substrate or a plastic substrate than a semiconductor transistor using an inorganic semiconductor such as silicon. In the case of an organic transistor, an element can be manufactured without using a vacuum process or a high-temperature process of 200 ° C. or higher, and printing techniques such as an ink jet method and a screen printing method, a spin coating method, a casting method, etc. The reason is that the device can be manufactured using a solution process. Therefore, organic transistors are expected to be applied to flexible displays and electronic tags. On the other hand, carrier properties of organic semiconductor materials and electrical properties such as contact resistance between organic semiconductor layers (organic semiconductor materials) and source / drain electrodes are still inferior to those of inorganic semiconductor devices. Improvement is an issue.

In particular, reducing the contact resistance at the interface between the organic semiconductor layer and the source and drain electrodes results in improved transistor characteristics such as improved mobility as a device, increased ON current, and lowered threshold voltage. This is because the organic semiconductor layer does not have carriers in its material, and unlike inorganic semiconductor layers, it is difficult to inject and control carriers by doping, and carriers are supplied by injection from the source electrode to the organic semiconductor layer. Therefore, the contact resistance at the interface between the source electrode and the organic semiconductor layer has a significant effect on the transistor characteristics. Similarly, injected carriers need to be efficiently extracted from the drain electrode side through the organic semiconductor layer. For this reason, reducing the contact resistance at the interface between the drain electrode and the organic semiconductor layer is also an important issue.

One of the causes of this contact resistance is that the injection barrier is caused by the existence of an energy gap between the work function of the metal used for the source and drain electrodes and the HOMO or LUMO level of the organic semiconductor material. The other is considered to be caused by low physical adhesion due to low affinity between different materials of the metal and the organic semiconductor material.

In order to solve such a problem, it is useful to form a monomolecular film having a dipole moment on the surfaces of the source electrode and the drain electrode. In Patent Document 1, as shown in FIG. 14, a gate electrode and a gate insulating layer 13 are formed on a substrate 111, and an organic semiconductor device 110 further includes a source electrode 115, a drain electrode 116, and an organic semiconductor layer 114. Discloses an organic semiconductor device 110 having charge

injection promoting layers

117 and 118 at least one of the interfaces between the organic semiconductor layer 114 and the source electrode 115 or the drain electrode 116. The direction of this dipole moment is specific to the direction in which the carriers flow. When the carriers are electrons, the direction of the electrons is preferably the same as the direction of the electrons. It is desirable that the direction is opposite to the direction. That is, in a general coplanar transistor such as a thin film transistor, it can be said that the preferred dipole moment directions on the source and drain electrodes are different directions regardless of the type of carrier.

Japanese Patent Publication “Japanese Patent Laid-Open No. 2005-294785 (Publication Date: October 20, 2005)”

However, it is complicated to form monomolecular films having different dipole moments on the source / drain electrodes, and there is a problem that the number of processes increases.

Monolayer formation is caused by a chemical reaction between atoms on the electrode surface and terminal functional groups of organic molecules. That is, the monomolecular film is formed only on the surface where the organic molecules can react and is selective. On the other hand, if the surface can react with the organic molecules, the monomolecular film is formed. In a general bottom contact type organic transistor formation method, a gate electrode, an insulating layer, a source / drain electrode, a modification of the source / drain electrode, and an organic semiconductor layer are formed in this order from the substrate. It is desirable that the layers located in the same plane are formed in the same process from the viewpoint of reducing the number of processes and from the viewpoint of easy alignment. However, when the same source / drain electrode material was used, the same monomolecular film was formed on both the source / drain electrodes when different monomolecular film formation processes were performed. It is impossible to make a monomolecular film.

Although there is no description of a specific manufacturing method in Patent Document 1, when the above structure is manufactured by a general method, a monomolecular film is formed after forming one of the source / drain electrodes. Further, it is expected that a method of sequentially forming the other electrode and the other monomolecular film in this order will be taken. When the source electrode and the drain electrode are manufactured in two steps, it is expected that the alignment of the electrodes is difficult and the number of processes is increased. Further, when forming the other electrode, since a monomolecular film is formed on one electrode, photolithography which is expected to be chemically damaged cannot be used. That is, it is difficult to form the source / drain electrodes with fineness and high accuracy.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an organic semiconductor device manufacturing method capable of selectively making different monomolecular films by a simple method. The purpose is to provide.

That is, the manufacturing method of the organic semiconductor device according to the present invention is to solve the above problems,
A first step of forming a gate electrode and a gate insulating layer on the substrate;
A second step in which the source electrode and the drain electrode are separated from each other and formed on the gate insulating layer formed by the first step;
A third step of forming a material layer made of a material or molecule having an electric dipole moment on the source electrode and the drain electrode;
Reversing the direction of the electric dipole moment from the negative electrode to the positive electrode of the material layer or material of the material layer formed on the source electrode or the material layer formed on the drain electrode, the source electrode over, provided with an injection-improvement layer facilitates migration of charge on the drain electrode, and the injection improving layer is a direction reverse of the electric dipole moment, extraction improving layer to facilitate the transfer of charges A fourth step of providing
And a fifth step of forming an organic semiconductor layer in contact with the injection improving layer and the extraction improving layer.

According to the above configuration, after the source electrode and the drain electrode are formed, the material layer having the same electric dipole moment direction is formed on both the source electrode and the drain electrode. For one of these, reverse the direction of the electric dipole moment to improve the injection of charge from the organic semiconductor layer to the electrode, and the extraction to improve the extraction of charge from the electrode to the organic semiconductor layer A fine electrode pattern can be formed by performing the process of separately forming the improvement layer. Specifically, before forming the injection improvement layer and the extraction improvement layer, a process (for example, photolithography) in which damage to the injection improvement layer and the extraction improvement layer is expected by forming the source electrode and the drain electrode is performed. It can be used. Therefore, it is possible to employ the above process that facilitates miniaturization of the electrode.

Moreover, in order to solve said subject, the manufacturing method of the other organic-semiconductor device based on this invention,
A method of manufacturing an organic semiconductor device having a p-type organic transistor and an n-type organic transistor,
A first step of forming a gate insulating layer on the gate electrode;
a second step of forming a source electrode and a drain electrode constituting the p-type organic transistor and a source electrode and a drain electrode constituting the n-type organic transistor on the gate insulating layer;
A third step of forming a material layer made of a material or molecule having an electric dipole moment on the source electrode and the drain electrode;
The material layer above the source electrode of the p-type organic transistor and the material layer above the drain electrode of the n-type organic transistor, or the material layer above the drain electrode of the p-type organic transistor and the source of the n-type organic transistor The material of the material layer on the electrode or the direction of the electric dipole moment from the negative electrode to the positive electrode of the molecule is reversed, and the p-type injection improving layer and the n-type organic transistor are formed on the source electrode of the p-type organic transistor. An n-type extraction improving layer is provided on the drain electrode, and the extraction improves the extraction of charge from each electrode to the organic semiconductor layer on the drain electrode of the p-type organic transistor and on the source electrode of the n-type organic transistor. A fourth step of providing an improvement layer;
and a fifth step of forming an organic semiconductor layer in contact with the injection improving layer and the extraction improving layer of the p-type organic transistor and an organic semiconductor layer in contact with the injection improving layer and the extraction improving layer of the n-type organic transistor. It is characterized by.

According to the above configuration, after forming the source electrode and the drain electrode at the same time, the material layer having the same electric dipole moment direction is formed on both the source electrode and the drain electrode. By reversing the direction of the electric dipole moment of one of the layers and separately forming the injection improving layer and the extraction improving layer, a fine electrode pattern can be formed. Specifically, before forming the injection improvement layer and the extraction improvement layer, a process (for example, photolithography) in which damage to the injection improvement layer and the extraction improvement layer is expected by forming the source electrode and the drain electrode is performed. It can be used. Therefore, it is possible to employ the above process that facilitates miniaturization of the electrode.

Other objects, features, and superior points of the present invention will be fully understood from the following description. The advantages of the present invention will become apparent from the following description with reference to the accompanying drawings.

As described above, the manufacturing method of the organic semiconductor device according to the present invention is as follows.
A first step of forming a gate electrode and a gate insulating layer on the substrate;
A second step in which the source electrode and the drain electrode are separated from each other and formed on the gate insulating layer formed by the first step;
A third step of forming a material layer made of a material or molecule having an electric dipole moment on the source electrode and the drain electrode;
Reversing the direction of the electric dipole moment from the negative electrode to the positive electrode of the material layer or material of the material layer formed on the source electrode or the material layer formed on the drain electrode, the source electrode An extraction improvement layer for promoting charge transfer is provided on the drain electrode, and an extraction improvement layer for promoting charge transfer, wherein the direction of the electric dipole moment is opposite to that of the injection improvement layer on the drain electrode. A fourth step of providing
And a fifth step of forming an organic semiconductor layer in contact with the injection improving layer and the extraction improving layer.

Moreover, in order to solve said subject, the manufacturing method of the other organic-semiconductor device based on this invention,
A method of manufacturing an organic semiconductor device having a p-type organic transistor and an n-type organic transistor,
A first step of forming a gate insulating layer on the gate electrode;
a second step of forming a source electrode and a drain electrode constituting the p-type organic transistor and a source electrode and a drain electrode constituting the n-type organic transistor on the gate insulating layer;
A third step of forming a material layer made of a material or molecule having an electric dipole moment on the source electrode and the drain electrode;
The material layer above the source electrode of the p-type organic transistor and the material layer above the drain electrode of the n-type organic transistor, or the material layer above the drain electrode of the p-type organic transistor and the source of the n-type organic transistor The material of the material layer on the electrode or the direction of the electric dipole moment from the negative electrode to the positive electrode of the molecule is reversed, and the p-type injection improving layer and the n-type organic transistor are formed on the source electrode of the p-type organic transistor. A fourth type in which an n-type extraction improving layer is provided on the drain electrode, and a p-type extraction improving layer is provided on the drain electrode of the p-type organic transistor and an n-type injection improving layer is provided on the source electrode of the n-type organic transistor. Process,
and a fifth step of forming an organic semiconductor layer in contact with the injection improving layer and the extraction improving layer of the p-type organic transistor and an organic semiconductor layer in contact with the injection improving layer and the extraction improving layer of the n-type organic transistor. It is characterized by.

According to the above-described configuration, it is possible to provide a method for manufacturing an organic semiconductor device capable of selectively producing different monomolecular films by a simple method.

It is sectional drawing which showed the structure of the organic transistor manufactured by the manufacturing method which concerns on one Embodiment of this invention. 2 illustrates a partial configuration of materials of an injection improvement layer and an extraction improvement layer of an organic transistor according to an embodiment of the present invention. It is sectional drawing which showed the manufacturing process of the organic transistor based on one Embodiment of this invention. It is sectional drawing which showed the manufacturing process of the organic transistor based on other embodiment of this invention. It is sectional drawing which showed the manufacturing process of the organic transistor based on other embodiment of this invention. It is sectional drawing which showed the manufacturing process of the organic transistor based on other embodiment of this invention. It is sectional drawing which showed the structure of the semiconductor device manufactured by the manufacturing method which concerns on one Embodiment of this invention. FIG. 8 is a circuit diagram showing an element circuit configuration of the semiconductor device shown in FIG. 7. It is a figure which shows the electrode pattern of the semiconductor device shown in FIG. It is sectional drawing which showed the manufacturing process of the semiconductor device based on one Embodiment of this invention. It is the figure which showed the structure of the TFT element manufactured by the manufacturing method which concerns on one Embodiment of this invention. It is sectional drawing which showed the structure of the TFT element manufactured by the manufacturing method which concerns on one Embodiment of this invention. It is sectional drawing which showed the structure of the TFT element manufactured by the manufacturing method which concerns on one Embodiment of this invention. It is sectional drawing which showed the structure of the organic transistor based on other embodiment of this invention. It is sectional drawing which showed the structure of the organic transistor of a comparative example. It is sectional drawing shown about the conventional structure.

[Embodiment 1]
An embodiment according to the present invention will be described below with reference to FIGS.

Hereinafter, the configuration of the organic transistor (organic semiconductor device) will be described first, and then the method for manufacturing the organic transistor, which is a feature of the present invention, will be described.

(1) Configuration of Organic Transistor The organic transistor in the present embodiment can be used as a field effect transistor mounted on various semiconductor devices, and an injection improvement layer is inserted between the source electrode and the organic semiconductor layer. In addition, an extraction improving layer is inserted between the drain electrode and the organic semiconductor layer.

FIG. 1 is a cross-sectional view showing the configuration of the organic transistor of the present embodiment. As shown in FIG. 1, the organic transistor 1 includes a substrate 11, a gate electrode 12, a gate insulating layer 13, a source electrode 14, a drain electrode 15, an organic semiconductor layer 16, an injection improving layer 40, and an extraction. And an improvement layer 50.

(substrate)
As the substrate 11, a silicon substrate, a quartz substrate, a glass substrate, or a resin substrate made of a material such as polycarbonate, polyetheretherketone, polyimide, polyester, or polyethersulfone can be used. In particular, considering the development of flexible devices, it is preferable to use a resin substrate.

The thickness of the substrate 11 applied in the present invention can be, for example, in the range of 10 μm to 1 mm, but the present invention is not limited to this.

(Gate electrode)
The gate electrode 12 is formed on the substrate 11 using a photolithographic method or the like.

As a material of the gate electrode 12, gold (Au), silver (Ag), copper (Cu), platinum (Pt), palladium (Pd), iron (Fe), aluminum (Al), tantalum (Ta), chromium ( Cr) and other metal materials, oxide conductors such as indium tin oxide (ITO), zinc oxide (ZnO) and tin oxide (SnO ₂ ), and a transparent material composed of indium oxide and zinc oxide which are a kind of oxide conductors. A conductive material can be mentioned. Two or more of these materials may be used in combination.

The gate electrode 12 may be an electrode made of an organic material such as polyaniline or polythiophene, or an electrode formed by applying conductive ink. Since these electrodes can be formed by applying an organic material or conductive ink, there is an advantage that the electrode forming process becomes extremely simple. Specific examples of the coating method include a spin coating method, a casting method, a pulling method, and other printing methods such as an inkjet printing method, a screen printing method, and a gravure printing method, and pattern printing is performed by these printing methods. You can also.

The film thickness of the gate electrode 12 depends on the conductivity of the material, but can be in the range of 50 to 1000 nm. The lower limit of the thickness of the gate electrode 12 varies depending on the conductivity of the electrode material and the adhesion strength with the substrate 11. On the other hand, the upper limit of the thickness of the gate electrode 12 is that when a gate insulating layer 13 and a source electrode 14-drain electrode 15 pair, which will be described later, are provided, the insulating coating by the gate insulating layer 13 at the step portion between the substrate 11 and the gate electrode 12 Is sufficient, and it is necessary not to cause disconnection in the electrode patterns of the source electrode 14 and the drain electrode 15 formed thereon.

(Gate insulation layer)
As shown in FIG. 1, the gate insulating layer 13 is formed on the surface of the substrate 11 where the gate electrode 12 is formed so as to cover the gate electrode 12 and the step portion of the gate electrode 12.

As with the gate electrode 12, the gate insulating layer 13 is made of polychloropyrene, polyethylene terephthalate, polyoxymethylene, polyvinyl chloride, polyvinylidene fluoride, cyanoethyl pullulan, polymethyl methacrylate, polysulfone, polycarbonate, polyvinyl phenol, polystyrene, polyimide, etc. It can be formed by applying a polymer material. Examples of coating methods include spin coating, casting, pulling, etc., as well as printing methods such as inkjet printing, screen printing, gravure printing, flexographic printing, and pattern printing using these printing methods. You can also.

Incidentally, it may be used conventional pattern process such as CVD, in which case _the, SiO 2, SiNx, inorganic material, such as _Al 2 _{O 3} are preferably used. Two or more of these materials may be used in combination.

The gate insulating layer 13 preferably has sufficient insulation to suppress leakage current and has a large capacitance per unit volume. The film thickness of the gate insulating layer 13 is set from both viewpoints. Is done. The specific film thickness is preferably in the range of 20 to 1000 nm when the gate insulating layer 13 is formed of a polymer material, and is preferably 10 to 500 nm when the gate insulating layer is formed of an inorganic material. It is preferable to be in the range. Insulating layers made of self-assembled monolayers with long-chain alkyls such as octadecylsilane monolayers (ODS-SAMs) can reduce the film thickness to the molecular length level. This is preferable because the capacity is increased. Moreover, it is desirable that the withstand voltage of the gate insulating layer 13 is 2 MV / cm or more, regardless of which material is used.

(Source electrode and drain electrode)
The source electrode 14 and the drain electrode 15 are formed on the gate insulating layer 13 as shown in FIG.

The material of the source electrode 14 and the drain electrode 15 is gold (Au), silver (Ag), copper (Cu), platinum (Pt), palladium (Pd), iron (Fe), aluminum (Al), tantalum (Ta). , Metal materials such as chromium (Cr) and alloy materials containing these metals, and oxidation of indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), tin oxide (SnO ₂ ), etc. A transparent conductive material made of indium oxide and zinc oxide, which is a kind of physical conductor and oxide conductor, can be used. Among them, the source electrode 14 and the drain electrode 15 are made of Au, Ag, ITO, ZnO, SnO ₂ , indium oxide and zinc oxide, which are easily chemically bonded to an injection improving layer 40 and an extraction improving layer 50 described later. It is preferable to use a transparent conductive material.

The source electrode 14 and the drain electrode 15 may be made of the same material or different materials. In the case of the same material, the material cost can be suppressed. On the other hand, in the case of another material, there is an advantage that the number of steps can be reduced. Specifically, when forming a self-assembled monolayer as an injection improvement layer and an extraction improvement layer, the surface of the electrode (bonding hand) will be different if different materials are used. By selecting the material of the layer and the extraction improving layer, the improving layer can be formed at a time. On the other hand, in the case of the same material, it is necessary to take four steps of forming the injection improving layer after forming the source electrode and forming the extraction improving layer after forming the drain electrode. In the case of another material, a combination of gold and ITO or a combination of silver and ITO is preferable.

(Organic semiconductor layer)
The organic semiconductor layer 16 is formed in a channel region (charge transport path region) between the source electrode 14 and the drain electrode 15.

The organic transistor 1 of the present embodiment can be used as a field effect transistor as described above, and can be applied to the case where the carrier is an electron (n-type channel), and the carrier is a hole (also referred to as a hole) (p It is also applicable to the case of a type channel). Therefore, the organic semiconductor layer 16 can be either a p-type channel material or an n-type channel material.

Specifically, pentacene, rubrene, oligothiophene, polythiophene, and their alkyl substituents can be used as the organic semiconductor layer 16 material for the p-type channel. Further, as the material of the organic semiconductor layer 16 for the n-type channel, C ₆₀ fullerene, fluorinated pentacene, and a perylene imide compound are preferable. Among these, pentacene and C ₆₀ fullerene are preferable because they have high carrier mobility and can realize high-speed operation.

(Injection improvement layer and extraction improvement layer)
The injection improving layer 40 is a layer made of a material or molecule having an electric dipole moment, which is disposed between the source electrode 14 and the organic semiconductor layer 16. When the carrier is a hole, the direction of the vector electric dipole moment from the negative electrode to the positive electrode of the material or molecule (hereinafter sometimes simply referred to as the electric dipole moment direction) is directed to the source electrode 14. On the other hand, when the carrier is an electron, the vector is directed to the organic semiconductor layer 16.

The extraction improving layer 50 is a layer made of a material or molecule having an electric dipole moment, which is disposed between the drain electrode 15 and the organic semiconductor layer 16. When the carrier is a hole, the vector is directed to the organic semiconductor layer 16, and when the carrier is an electron, the vector is directed to the drain electrode 15.

The injection improving layer 40 and the extraction improving layer 50 may be any material or molecule that can be applied with the manufacturing method of the injection improving layer and the extraction improving layer described later.

As a specific material or molecule, at least one of the injection improving layer 40 and the extraction improving layer 50 is represented by the following general formula (1);
XAY (1)
Is an organic thin film having an electric dipole moment formed by aggregation of organic compounds represented by

Note that the organic thin film having an electric dipole moment means a thin film having a thickness corresponding to the size of one molecule. Note that the structure represented by the general formula (1) may be partially covalently bonded to form a dimer, trimer or oligomer structure, but the layer thickness is one molecule. It is.

The substituent X in the general formula (1) is bonded to the molecule represented by the general formula (1) by chemically bonding to the atoms constituting the source electrode 14 and the drain electrode 15 to thereby combine the general formula (1). When the molecules represented by (1) are assembled, they have a function of forming self-assembled monolayers (SAMs: Self-Assembled Monolayers).

Specific examples of the substituent X include
^{_{X: -SH, -SiR 1 3,}} -CN, -

COR

2, or _{^{^{-SO 2 R 2,, -POR 2}}} 2
Is mentioned. Any ^one of R ¹ is a methoxy group (—OMe), an ethoxy group (—OEt), or a chloro group (—Cl), and any one of the R ² is a hydroxy group ( -OH) and a chloro group (-Cl). In the carboxylic acid moiety (—COR ² ) and sulfonic acid moiety (—SO ₂ R ² ), R ² is a hydroxy group (—OH) or a chloro group (—Cl). Similarly, at the phosphonic acid moiety, at least one of the two R ² groups is a hydroxy group (—OH) or a chloro group (—Cl), but the other R ² groups are not involved in binding. A methyl group or a methoxy group.

Of these, the substituent X is preferably a thiol group (—SH). By using the substituent X as a thiol group, a covalent bond can be formed between the atoms constituting the source electrode 14 and the drain electrode 15 and the thiol group, and the distance between the bonding sites can be made relatively short. It is possible to further reduce the contact resistance. In particular, if at least one of the source electrode 14 and the drain electrode 15 is selected from a material containing gold (Au) atoms and a chemical bond is formed between the gold (Au) atoms and the thiol group (—SH), the electrode An improvement layer is fixed on the organic transistor 1, and deterioration of the improvement layer due to an electric field or the like when driving the organic transistor 1 can be suppressed, so that the life of the organic transistor 1 can be extended.

In addition, the HOMO orbit of the aromatic thiol formed by combining the main chain skeleton A and the thiol group of the substituent X described later also exists in the vicinity of the sulfur atom, and the orbit responsible for electrical conduction extends to the vicinity of the electrode material. For the above reason, since the resistance of the connection portion between the improvement layer and the electrode is lowered, the contact resistance as a transistor can be further reduced.

The substituent Y in the general formula (1) is in contact with the organic semiconductor layer 16 on the surface of the layer. The substituent Y is a substituent that can be converted by a photochemical reaction, an oxidation reaction, or a reduction reaction, and consists of an electron withdrawing group or an electron withdrawing group. Here, the electron donating group and the electron withdrawing group refer to those in which Hammett's substituent constants are negative and positive, respectively.

Specific electron-withdrawing groups Y ¹ that can be used as the substituent Y include a nitro group (—NO ₂ ), a chloromethyl group (—CH ₂ Cl), an aldehyde group (—CHO), and an azide group (—N ₃ ). , A cyano group (—CN), a carboxyl group (—COOH), a carbonyl group (—COR ³ ), an alkoxycarbonyl group (—COOR ³ ), a halogen group (—F, —Cl, —Br, and ^ —I), Examples thereof include an alkoxysilane group (—Si (OR ³ ) ₃ ) and a trifluoromethyl group (—CF ₃ ) (wherein R ¹ is a linear alkyl group having 1 to 3 carbon atoms).

Specific electron donor groups ^{Y 2} which can be used as the substituent Y is an amino group _{^{^{(-NH 2, -NHR 4, -NR}}} 4 R 5), ethylene group ^{(-C = C-R 4)} , an imino group (—C═N—R ⁴ ) and a methylene hydroxyl group (—CH ₂ (OH)). R ⁴ to R ⁵ all represent a linear alkyl group having 1 to 3 carbon atoms.

When the substituent Y is an electron withdrawing group, the vicinity of Y ¹ is negatively charged, so that an electric dipole moment in the direction from the organic semiconductor layer to the electrode can be formed in the injection improving layer and the extraction improving layer. . In addition, when the substituent Y is an electron donating group, the vicinity of Y ² is positively charged. Therefore, an electric dipole moment in the direction from the electrode to the organic semiconductor layer is formed in the injection improving layer and the extraction improving layer. Can do.

As the main chain skeleton A in the general formula (1), the aromatic main chain skeleton shown in FIG. 2 can be used. Aromatic main chain skeletons include monocyclic structures such as benzene, pyridine, thiophene, pyrrole, condensed ring structures such as naphthalene, anthracene, tetracene, pentacene, biphenyl, bipyridyl, terphenyl, terthiophene, etc. Those having the following polycyclic structure are preferred. In addition to the aromatic main chain skeleton, an aliphatic main chain skeleton may be used. Examples of the aliphatic main chain skeleton include linear alkanes having 1 to 20 carbon atoms (— (CH ₂ ) n—n = 1 to 20). Of these, those having 1 to 6 carbon atoms are preferred from the viewpoint of reducing the electrical resistance of the injection improving layer and the extraction improving layer itself.

In addition, since the main chain skeleton A is an aromatic main chain skeleton has π electrons in the main chain skeleton, the electric resistance of the injection improving layer and the extraction improving layer itself is further reduced. A reduction in contact resistance is realized.

The molecule represented by the general formula (1) has a functional group chemically bonded to the electrode material at one end in the long axis direction of the molecule, and an electron withdrawing group or electron donating group at the opposite end. ing. Therefore, self-assembled monolayers (SAMs) can be formed on each electrode, and an electron withdrawing group or electron donating group can be arranged on the opposite side of the electrode. In self-assembled monolayers, the orientation of the molecules is controlled, so the electric dipole moment can be aligned. Therefore, the charge injection effect or the charge extraction effect due to the electric dipole moment can be further enhanced.

Furthermore, the film thickness of the self-assembled monolayer is substantially the same as the molecular length of the molecules forming the self-assembled monolayer. Therefore, the injection improving layer 40 and the extraction improving layer 50 can be thinned to the molecular length of the molecules forming the self-assembled monolayer. Thereby, it is possible to reduce the resistance of the injection improving layer 40 and the extraction improving layer 50 itself.

(2) Manufacture of Organic Transistor Next, a method for manufacturing the organic transistor of the present embodiment having the above-described configurations will be described.

In this embodiment, after forming the source electrode and the drain electrode, a material made of a composition constituting the injection improving layer is laminated on both the source electrode and the drain electrode, and then a part of the material layer is modified. Thus, a characteristic method of forming an extraction improvement layer is adopted to realize an injection improvement layer and an extraction improvement layer.

FIG. 3 is a diagram showing a method for manufacturing the organic transistor of the present embodiment.

(First step: Gate electrode / gate insulating layer forming step)
First, after forming a gate electrode material on the entire surface of the substrate 11 by, for example, sputtering, pattern formation is performed using existing photolithography. Thereby, the gate electrode 12 is formed as shown in FIG. In Example 1 described later, an aluminum film having a thickness of 60 nm is used as the gate electrode 12.

Next, the gate electrode 12 is coated by sputtering using a gate insulating layer material. Thereby, the gate insulating layer 13 is formed as shown in FIG. In Example 1 described later, silicon nitride having a thickness of 200 nm is used as the gate insulating layer 13.

(Second step: source / drain electrode forming step)
Next, the above-described source electrode material is formed on the gate insulating layer 13 by performing patterning by existing photolithography. In this case, when the source electrode material and the drain electrode material are made of the same material, the source electrode and the drain electrode can be formed in the same process. Thereby, the source electrode 14 and the drain electrode 15 are formed as shown in FIG. In Example 1 to be described later, the source electrode 14 and the drain electrode 15 are formed by depositing 60 nm of ITO by patterning by photolithography.

On the other hand, the source electrode material and the drain electrode material may be made of different materials. For example, one electrode may be formed by sequentially vacuum-depositing 5 nm of chromium and 60 nm of gold thereon through a metal mask. Chromium at this time plays a role of bringing gold and the substrate 11 into close contact.

The distance (channel length) between adjacent sides of the source electrode 14 and the drain electrode 15 can be 5 to 200 μm. Further, the length (channel width) of adjacent sides of the source electrode 14 and the drain electrode 15 can be set to 100 to 10,000 μm.

Note that the method for forming the source electrode and the drain electrode is not limited to the patterning by the existing photolithography, and vapor deposition through a metal mask, which is a general electrode forming method, sputtering, ink jet, etc. It is also possible to use it. However, according to the manufacturing method according to the present invention, since the source electrode and the drain electrode can be formed in the same process, the source electrode and the drain electrode can be formed using precise photolithography capable of further miniaturization. Is significant in that it can be formed.

(Third step: Improvement layer forming step)
Next, as shown in FIG. 3C, on the source electrode 14 and the drain electrode 15, layers (SAMs) made of a material having a composition constituting the implantation improving layer are formed as the improving layer 17 (material layer). To do.

Here, as will be described later, in the present embodiment, after the improvement layer 17 is formed, only the improvement layer 17 formed on the drain electrode 15 is subjected to a modification (conversion) process, and the portion subjected to the process is improved. A technique of modifying the layer 17 to the extraction improving layer 50 is employed, and a photochemical reaction is used as the modification (conversion) process.

That is, as the improvement layer 17 material used in this step, a material that can convert the configuration of the injection improvement layer into the configuration of the extraction improvement layer by photochemical reaction may be selected and adopted. Specifically, when the improvement layer 17 formed on the drain electrode 15 is modified to the extraction improvement layer 50 using a photochemical reaction, the functional group at the end that contacts the organic semiconductor layer is used as the material. Molecules having a chloromethyl group or a nitro group can be used.

As the formation method of the improvement layer 17 (self-assembled monolayer SAMs), there are the following three formation methods.

(Formation method 1)
A solution of a material for forming SAMs is prepared, and the substrate is immersed therein. By standing or stirring the solution at a temperature of about 0 to 100 ° C., a monomolecular film is formed. Thereafter, the substrate is washed with a solvent in order to remove the physically attached material. By adopting the forming method 1, there is an advantage that it is simple because no special apparatus is required. In addition, it is easy to enhance the interaction between molecules, and a monomolecular film with high orientation can be obtained. It is suitable for a molecule that does not self-polymerize (for example, a molecule having a thiol group or a phosphonic acid group).

(Formation method 2)
A small bottle containing a substrate and a material for forming SAMs is sealed in a sealed container and heated to about 50 to 150 ° C. Thereafter, the substrate is washed with a solvent in order to remove the physically attached material. By adopting the forming method 2, since heating is performed, there is an advantage that the reaction is fast and the time for the forming process can be shortened. Even if a self-polymerizing material is used, a uniform monomolecular film can be obtained. The self-polymerizing material generates a self-polymer in the reaction system simultaneously with the formation of the monomolecular film. When the polymer is attached to the substrate, it is not a uniform monomolecular film. However, in this method, the polymer has a high molecular weight and a high boiling point, so it does not evaporate and does not reach the substrate. As a result, a uniform monomolecular film is obtained.

(Formation method 3)
A solution of a material for forming SAMs is spin-coated or dip-coated and applied onto a substrate. Thereafter, the substrate is chemically bonded to the substrate by heating the substrate to about 50 to 150 ° C. or exposing the substrate to vapor that promotes a dehydration condensation reaction such as hydrochloric acid or ammonia. Further, in order to remove the excessively attached material, the substrate is washed with a solvent. Employing the forming method 3 has an advantage that it is economical because the amount of the material for forming the SAMs is small. In addition, since the heating is performed, the reaction is fast and the time for the forming process can be shortened.

The improvement layer 17 can be formed on the source electrode 14 and the drain electrode 15 by the above forming method.

(Fourth step: partial modification step by photochemical reaction)
Next, as shown in FIG. 3D, only the improvement layer 17 formed on the drain electrode 15 is caused to undergo a photochemical reaction as a modification (conversion) treatment to replace the functional group of the improvement layer 17. Thus, the improvement layer 17 formed on the drain electrode 15 is modified (converted) into the extraction improvement layer 50.

Examples of materials that can be modified by photochemical reaction include aromatic or aliphatic compounds having a methylchloro group or an azide group. The above functional group can be modified to an aldehyde group and an azide group to an amino group by photochemical reaction.

For example, when p-chloromethylphenyltrimethoxysilane is used as the improvement layer 17, first, the chloromethyl group of the improvement layer 17 on the drain electrode 15 is converted into an aldehyde group by a photochemical reaction ((e in FIG. 3) )).

Here, the photochemical reaction refers to a chemical reaction in which a functional group exposed on the surface is converted into another functional group by irradiating the surface of the improvement layer 17 to be irradiated with light. When the functional group exposed on the surface of the improvement layer 17 is irradiated with light, it is excited by light energy and is in a state where it is easy to emit or give electrons. When another chemical species (for example, oxygen or water) approaches, electrons are transferred between molecules, and a chemical reaction that is difficult to proceed under a normal atmosphere proceeds.

The photoirradiation may be performed using a photomask in which only the improvement layer 17 on the drain electrode 15 is optically empty. Or the method of irradiating locally using a condensing lens or a laser is mentioned.

The light to be irradiated is preferably irradiated with a wavelength that can excite the site to be reacted in the molecule to be irradiated. Specifically, it may be light in the wavelength range of 180 to 600 nm. If oxygen is required, such as when converting a group to an aldehyde group, the irradiation is preferably performed in an air atmosphere. In Example 1 described later, light of 196 nm is irradiated for 1 minute in an air atmosphere.

Irradiation is preferably performed using a deuterium lamp, a xenon lamp or a halogen lamp as a light source. When irradiating vacuum ultraviolet light with a deuterium lamp, it is performed in a reduced-pressure atmosphere in consideration of atmospheric absorption. It is preferable. When a laser is used, a helium-neon laser, an argon ion laser, a YAG laser, or the like can be used.

Next, the converted functional group exposed on the surface of the improvement layer 17 on the drain electrode 15 is further converted into another functional group. For example, the extraction improving layer 50 having the amino group exposed on the surface can be formed on the drain electrode 15 by chemically reacting the aldehyde group with one amino group of 1,4-phenylenediamine (FIG. 3). (F)).

According to this step, the functional group exposed on the surface is converted (for example, converted from a chloromethyl group to an amino group), so that the electric dipole moment vector on the drain electrode 15 is inverted. Improved layers can be formed.

It should be noted that the functional group of the material (improving layer 17) composed of the composition constituting the injection improving layer is not limited to the above-described steps and materials, and the functional group of the extraction improving layer 50 can be finally replaced. If it is a material applicable to this, it can employ | adopt.

(Fifth step: Organic semiconductor layer formation step)
Next, as shown in FIG. 3G, the organic semiconductor layer 16 is formed by vacuum deposition using the organic semiconductor layer material described above so as to be in contact with the injection improving layer 40 and the extraction improving layer 50. The film thickness of the organic semiconductor layer 16 can be 10 to 1000 nm. In Example 1, the organic semiconductor layer 16 having a film thickness of 60 nm, for example, is formed through a metal mask using pentacene as the organic semiconductor layer material.

(Characteristics of organic transistors)
The characteristics of the organic transistor obtained by the above method will be described in detail in Example 1 described later, but both the mobility and the ON / OFF ratio are good, and the interface between the source electrode / organic semiconductor layer and the interface between the organic semiconductor layer / drain electrode The contact resistance can be suppressed to be lower than that of an element having no injection improvement layer and no extraction improvement layer.

In addition, evaluation of contact resistance can be evaluated using Transmission Line Model (TLM) method which is well-known methods, such as Solid-State Electronics 47 (2003) 259. More specifically, the source electrode - voltage Vd between the drain electrode when the -30 V, to evaluate the drain current Id in the ON state (Vg = -30 V), the overall resistance Rt from the source electrode to the drain electrode ;
Rt = 2Rc + Rch
(Where Rc is the contact resistance of the source electrode / organic semiconductor layer and drain electrode / organic semiconductor layer, and Rch is the resistance of the channel portion)
Is calculated from Rt = Vd / Id. Further, Rt is plotted against the channel length, and the value when the channel length is 0 (y intercept) is defined as the contact resistance.

(Operational effect of the first embodiment)
As described above, according to the manufacturing method of this embodiment, after the source electrode and the drain electrode are simultaneously formed, the improvement layer 17 in which the direction of the electric dipole moment is the same for both the source electrode 14 and the drain electrode 15. And by reversing the direction of the electric dipole moment of one of the improvement layers 17 by a photochemical reaction, and separately forming the injection improvement layer 40 and the extraction improvement layer 50, a fine electrode is formed. Pattern formation is possible. More specifically, a process in which the source electrode 14 and the drain electrode 15 are formed before the injection improvement layer 40 and the extraction improvement layer 50 are formed, and damage to the injection improvement layer 40 and the extraction improvement layer 50 is expected ( For example, photolithography) can be used, and the use of the above process facilitates miniaturization of the electrode.

Further, as described with reference to FIG. 3, by performing the partial modification process using a chemical reaction by light irradiation, patterning by light irradiation with high directivity and high resolution is possible.

In the present embodiment, a self-assembled monolayer is formed as the material layer 17 formed on the source electrode 14 and the drain electrode 15, but a self-assembled molecular layer laminate film in which self-assembled molecular layers are laminated. It may be.

[Embodiment 2]
FIG. 4 is a diagram showing a method for manufacturing the organic transistor of this embodiment. In the organic transistor of this embodiment, the substrate 11 is made of glass, the gate electrode 12 is made of aluminum, the gate insulating layer 13 is made of silicon dioxide, the source electrode 14 and the gate electrode 15 are made of chromium, for example, as in Example 2 described later. Formed by sequentially vacuum-depositing gold through a metal mask, the organic semiconductor layer 16 is C ₆₀ fullerene, the injection improving layer 40 and the extraction improving layer 50 are each a monomolecular film made of p-aminobenzenethiol and p- The structure which is a monomolecular film which consists of nitrobenzene thiol can be mentioned.

In the first embodiment, a photochemical reaction is used as a modification process applied to a part of the improvement layer 17, whereas in this embodiment, an oxidation reaction is used.

In the present embodiment, (first step: gate electrode / gate insulating layer forming step), (second step: source electrode / drain electrode forming step), and (fifth step) described in the first embodiment are described. Step: The organic semiconductor layer forming step) is the same as the step itself. Therefore, description of these steps is omitted in this embodiment. Therefore, below, an improvement layer formation process and the partial modification process following this are demonstrated.

(Third step: Improvement layer forming step)
As shown in FIG. 4A, with the source electrode 14 and the drain electrode 15 formed on the gate insulating layer 13, as shown in FIG. 4B, the improvement layer 17 (material layer) As described above, layers (SAMs) made of a material having a composition constituting the injection improving layer are formed.

In the present embodiment, as described in the partial modification step described later, only the improvement layer 17 formed on the drain electrode 15 after the formation of the improvement layer 17 is subjected to the modification (conversion) process, and the process is performed. A technique of modifying the partial improvement layer 17 to the extraction improvement layer 50 is employed, and an oxidation reaction is employed as the modification (conversion) treatment. Therefore, the material of the improvement layer 17 used in this step may be selected and adopted by a material that can convert the configuration of the injection improvement layer into the configuration of the extraction improvement layer by an oxidation reaction. Specifically, a molecule having a terminal functional group that contacts the organic semiconductor layer 16 having an amino group or an ethylene group can be used.

The formation method of the improvement layer 17 (self-assembled monolayer SAMs) includes the three formation methods (formation method 1) to (formation method 3) described above. For example, in the present embodiment, the monolayer improvement layer 17 made of p-aminobenzenethiol can be formed. As an example of the formation method in this case, the substrate before the improvement layer 17 is formed is immersed in a solution of 1 mM p-aminobenzenethiol for 3 hours, and after the immersion, the material physically attached is removed by washing with ethanol. Then, the improvement layer 17 can be formed.

(Fourth step: partial modification step by oxidation reaction)
Next, as shown in FIG. 4C, only the improvement layer 17 formed on the drain electrode 15 is subjected to a modification process to cause an oxidation reaction, thereby causing an extraction improvement layer 50 on the drain electrode 15. Form.

Examples of materials that can be modified by an oxidation reaction include aromatic or aliphatic compounds having an amino group, an alcohol group, an aldehyde group, or an ethylene group. The functional group can be modified by an oxidation reaction, the amino group can be modified to a nitro group, the alcohol group can be modified to an aldehyde group, the aldehyde group can be modified to a carboxyl group, and the ethylene group can be modified to a carboxyl group.

In FIG. 4C, an atomic force microscope (AFM) which is one of scanning probe microscopes is used to oxidize amino groups exposed on the surface of the improvement layer 17 and convert them into nitro groups. Yes. Specifically, by using an AFM probe coated with gold, a voltage of +3 V is applied to the drain electrode, and the oxidation reaction is performed by scanning the improvement layer 17 in the atmosphere. It is carried out.

Thus, the organic transistor shown in FIG. 4D can be finally manufactured by performing the oxidation reaction.

In addition, as a method for confirming that the amino group was converted to the nitro group, confirmation was made from the change in the work function of gold by atmospheric photoelectron spectroscopy and the shift of the peak of the 1s orbital of nitrogen by X-ray photoelectron spectroscopy. There is a technique to do. For example, if the work function of gold is 4.8 eV when the improvement layer is not modified, the p-aminobenzenethiol treatment shows a work function smaller than the unmodified value, and the oxidation treatment The result is larger than the unmodified value, and a result supporting the inversion of the dipole moment can be obtained.

(Characteristics of organic transistors)
The characteristics of the organic transistor obtained by the above method will be described in detail in Example 2 to be described later, but both the mobility and the ON / OFF ratio are good, and the interface between the source electrode / organic semiconductor layer and the interface between the organic semiconductor layer / drain electrode The contact resistance can be suppressed to be lower than that of an element having no injection improvement layer and no extraction improvement layer.

(Operational effect of the second embodiment)
As described above, according to the manufacturing method of this embodiment, after forming the source electrode and the drain electrode at the same time, both the source and drain

electrodes

14 and 15, improving layer orientation of the electric dipole moment is the same 17 In addition, the direction of the electric dipole moment is reversed by an oxidation reaction of one of the improvement layers 17, and the injection improvement layer 40 and the extraction improvement layer 50 are separately formed. A fine electrode pattern can be formed. More specifically, a process in which damage to the injection improvement layer 40 and the extraction improvement layer 50 is expected by forming the source electrode 14 and the drain electrode 15 before forming the injection improvement layer 40 and the extraction improvement layer 50 ( For example, photolithography) can be used, and the use of the above process facilitates miniaturization of the electrode.

In particular, the partial modification step shown in the present embodiment can reverse the dipole moment in one process by converting an amino group into a nitro group by an oxidation reaction, which reduces the number of steps. There is an effect that it is possible.

Also, as shown in the partial modification step shown in the present embodiment, by oxidizing with AFM, there is an effect that the area to be oxidized can be patterned.

(Modification of Embodiment 2)
The manufacturing method of this modification is demonstrated based on FIG. The oxidation reaction used in the partial modification step is different between the second embodiment and this modification.

First, through FIGS. 5A and 5B, material layers 17 (SAMs), which are monomolecular films made of a material having a composition constituting an injection improving layer, are formed on the source electrode 14 and the drain electrode 15. .

Subsequently, in this modified example, as shown in FIG. 5C, the material layer 17 composed of amino groups was oxidized and converted into nitro groups. Specifically, the substrate is immersed in the electrolyte solution 60, and a voltage of +3 V is applied between the drain electrode and the counter electrode 61 in the electrolyte solution. As a result, the organic transistor shown in FIG. 5D can be finally manufactured.

As in this modification, a voltage is applied electrochemically between the electrode whose direction of dipole moment is to be reversed and the counter electrode through the medium that conducts electrical conduction, such as an electrolyte solution. Oxidation makes it possible to convert molecules formed on the electrode at a time. Also, even if there are multiple elements on one substrate, it is possible to oxidize all the molecules at once by electrically connecting the electrodes to be oxidized, thus shortening the processing time. Is possible.

[Embodiment 3]
FIG. 6 is a diagram showing a method for manufacturing the organic transistor of this embodiment. In the organic transistor of this embodiment, the substrate 11 is made of glass, the gate electrode 12 is made of aluminum, the gate insulating layer 13 is made of silicon dioxide, the source electrode 14 and the gate electrode 15 are made of chromium, for example, as in Example 3 described later. Formed by sequentially vapor-depositing gold through a metal mask, the organic semiconductor layer 16 is pentacene, the injection improvement layer 40 and the extraction improvement layer 50 are each a monomolecular film made of p-nitrobenzenethiol and p-aminobenzenethiol The structure which is the monomolecular film which consists of can be mentioned.

In the first embodiment, a photochemical reaction is used to form the injection improvement layer and the extraction improvement layer, whereas in this embodiment, a reduction reaction is used.

In the present embodiment, (first step: gate electrode formation step), (second step: source electrode formation step), (second step: drain electrode formation step) described in the first embodiment, And about the (5th process: organic-semiconductor-layer formation process), the process itself is the same. Therefore, description of these steps is omitted in this embodiment. Therefore, below, an improvement layer formation process and the partial modification process following this are demonstrated.

(Third step: Improvement layer forming step)
As shown in FIG. 6A, with the source electrode 14 and the drain electrode 15 formed on the gate insulating layer 13, as shown in FIG. 6B, the improvement layer 17 (material layer) As described above, layers (SAMs) made of a material having a composition constituting the injection improving layer are formed.

In the present embodiment, as described in the partial modification step described later, only the improvement layer 17 formed on the drain electrode 15 after the formation of the improvement layer 17 is subjected to the modification (conversion) process, and the process is performed. A technique of modifying the partial improvement layer 17 to the extraction improvement layer 50 is employed, and a reduction reaction is employed as the modification (conversion) process.

Therefore, the material for the improvement layer 17 used in this step may be selected from materials that can convert the configuration of the injection improvement layer into the configuration of the extraction improvement layer by a reduction reaction. Specifically, a molecule in which the terminal functional group in contact with the organic semiconductor layer 16 has a nitro group or a carbonyl group can be used.

The formation method of the improvement layer 17 (self-assembled monolayer SAMs) includes the three formation methods (formation method 1) to (formation method 3) described above. For example, in this embodiment, the improvement layer 17 can be formed by immersing the substrate in a solution of 1 mM p-nitrobenzenethiol for 3 hours, and then immersing and washing with ethanol.

(Fourth step: partial modification step by reduction reaction)
Next, as shown in FIG. 6C, only the improvement layer 17 formed on the drain electrode 15 is modified (converted) by a reduction reaction, and the extraction improvement layer 50 is formed on the drain electrode 15. Form.

Examples of materials that can be modified by a reduction reaction include aromatic or aliphatic compounds having a nitro group, a carbonyl group, an aldehyde group, or an imino group. The functional group can be modified by a reduction reaction, the nitro group can be modified to an amino group, the carbonyl group can be modified to an alcohol group, and the imino group can be modified to an amino group or an aldehyde group.

Similarly to the second embodiment, also in FIG. 6C, the monomolecular film (material layer) 17 made of a nitro group can be reduced and converted to an amino group by AFM or electrochemically. . When the AFM is used, scanning is performed by applying a voltage of −3 V in the atmosphere between the probe needle and the drain electrode. On the other hand, when an electrochemical method is used, the substrate is immersed in an electrolyte solution, and −3 V is applied between the counter electrode and the drain electrode. The confirmation that the nitro group has been converted to the amino group can be confirmed by the same technique as that described in the second embodiment.

Thus, the reduction reaction is carried out to finally produce the organic transistor shown in FIG. 6 (d).

(Characteristics of organic transistors)
The characteristics of the organic transistor obtained by the above method will be described in detail in Example 3 to be described later, but both the mobility and the ON / OFF ratio are good, and the source electrode / organic semiconductor layer interface and the organic semiconductor layer / drain electrode interface The contact resistance can be suppressed to be lower than that of an element having no injection improvement layer and no extraction improvement layer.

(Operational effect of the third embodiment)
As described above, according to the manufacturing method of this embodiment, after forming the source electrode and the drain electrode at the same time, both the source and drain

electrodes

14 and 15, improving layer orientation of the electric dipole moment is the same 17 In addition, the direction of the electric dipole moment of one of the improvement layers 17 is reversed by a reduction reaction to separate the injection improvement layer 40 and the extraction improvement layer 50 from each other. A fine electrode pattern can be formed. More specifically, a process in which damage to the injection improvement layer 40 and the extraction improvement layer 50 is expected by forming the source electrode 14 and the drain electrode 15 before forming the injection improvement layer 40 and the extraction improvement layer 50 ( For example, photolithography) can be used, and the use of the above process facilitates miniaturization of the electrode.

In particular, the partial modification step shown in this embodiment can reverse the dipole moment in one process by converting the nitro group to an amino group by a reduction reaction, and the number of steps can be reduced. There is an effect that it is possible.

Also, as shown in the partial modification step shown in the present embodiment, there is an effect that the area to be reduced can be patterned by reducing with AFM.

[Embodiment 4]
FIG. 7 is a cross-sectional view showing a schematic configuration of an organic semiconductor device manufactured by the manufacturing method of the present embodiment. The manufacturing method according to the present invention can also be applied to the semiconductor device shown in FIG. In the following description, unless otherwise specified, the same members as those used in Embodiment 1 can be used with the same member numbers and the description thereof is omitted.

(1) Configuration of Semiconductor Device As shown in FIG. 7, a semiconductor device (organic semiconductor device) 10 includes a p-type organic transistor (hereinafter simply referred to as a p-type transistor) P1 formed on the same substrate 11. In addition, it is formed of an n-type organic transistor (hereinafter simply referred to as an n-type transistor) N1. The p-type transistor P1 and the n-type transistor N1 are field effect transistors using an organic material for the semiconductor layer.

The p-type transistor P 1 includes a substrate 11, a gate electrode 12 (first gate electrode) for the p-type transistor formed on the substrate 11, and a gate insulation formed on the substrate 11 so as to cover the gate electrode 12. The source electrode 14 (first source electrode) for the p-type transistor and the drain electrode 15 (first drain electrode) for the p-type transistor formed on the layer 13, the gate insulating layer 13, and the gate electrode 12. A bottom gate having a p-type organic semiconductor layer (hereinafter also simply referred to as a p-type semiconductor layer) 16 formed on the gate insulating layer 13, the source electrode 14, and the drain electrode 15 so as to overlap Type transistor.

The p-type transistor P <b> 1 is further provided with a p-type implantation improvement layer 40 </ b> P between the source electrode 14 and the p-type semiconductor layer 16, and p-type extraction is performed between the drain electrode 15 and the p-type semiconductor layer 16. The improvement layer 50P is provided.

On the other hand, the n-type transistor N1 is formed on the substrate 11 so as to cover the substrate 11, the gate electrode 22 (second gate electrode) for the n-type transistor formed on the substrate 11, and the gate electrode 22. Gate insulating layer 13, source electrode 24 (second source electrode) for n-type transistor and drain electrode 25 (second drain electrode) for n-type transistor formed on gate insulating layer 13, and gate An n-type organic semiconductor layer (hereinafter also simply referred to as an n-type semiconductor layer) 26 formed on the gate insulating layer 13, the source electrode 24, and the drain electrode 25 is provided so as to overlap with the electrode 22. A bottom-gate transistor.

The n-type transistor N1 is further provided with an n-type extraction improving layer 50N between the drain electrode 25 and the n-type semiconductor layer 26, and an n-type implantation between the source electrode 24 and the n-type semiconductor layer 26. The improvement layer 40N is provided.

In the semiconductor device 10, not only the substrate 11 but also the gate insulating layer 13 is commonly used in the p-type transistor P1 and the n-type transistor N1.

In the semiconductor device 10, the drain electrode 15 of the p-type transistor P1 and the drain electrode 25 of the n-type transistor N1 are electrically connected. In this configuration, the drain electrode 15 and the drain electrode 25 are physically connected by being in physical contact, but the drain electrode 15 and the drain electrode 25 are physically separated from each other. The drain electrode 15 and the drain electrode 25 may be electrically connected through the metal wiring.

FIG. 8 is a circuit diagram showing an element circuit of the semiconductor device 10. The semiconductor device 10 has a gate structure in which a p-type transistor P1 and an n-type transistor N1 are complementarily connected, and forms an inverter circuit such as a CMOS circuit as shown in FIG.

As shown in FIG. 8, in the semiconductor device 10, from Vdd to Vss, the source electrode 14 of the p-type transistor P1, the drain electrode 15 of the p-type transistor P1, the drain electrode 25 of the n-type transistor N1, and the n-type transistor N1. The p-type transistor P1 and the n-type transistor N1 are formed so that the source electrodes 24 are arranged in this order. That is, the semiconductor device 10 forms an inverter circuit that applies a positive voltage to Vdd.

Each of the p-type injection improvement layer 40P and the p-type extraction improvement layer 50P provided in the p-type transistor P1 is a layer for promoting charge movement. Specifically, the p-type injection improving layer 40P provided between the source electrode 14 and the p-type semiconductor layer 16 changes from the work function level of the source electrode 14 to the HOMO level of the p-type semiconductor layer 16. This is a layer that promotes injection of electric charges (in this case, holes h ⁺ ). On the other hand, the p-type extraction improving layer 50P provided between the drain electrode 15 and the p-type semiconductor layer 16 has a charge (hole) from the HOMO level of the p-type semiconductor layer 16 to the level of the work function of the drain electrode 15. h ⁺ ) is a layer that promotes extraction.

Each of the n-type extraction improving layer 50N and the n-type injection improving layer 40N provided in the n-type transistor N1 is also a layer for promoting charge movement. Specifically, the n-type extraction improving layer 50N provided between the drain electrode 25 and the n-type semiconductor layer 26 has a charge (in this case, an electron) from the LUMO level of the n-type semiconductor layer 26 to the drain electrode 25. e ⁻ is a layer that promotes extraction. On the other hand, the n-type injection improving layer 40N provided between the source electrode 24 and the n-type semiconductor layer 26 has a charge (electron) from the work function level of the source electrode 24 to the LUMO level of the n-type semiconductor layer 26. e ⁻ ) is a layer that promotes injection.

Each improvement layer having such a function is formed using molecules having an electric dipole moment.

For example, it can be used for the p-type injection improving layer 40P that promotes the injection of holes h ⁺ into the p-type semiconductor layer 16 and the n-type extraction improving layer 50N that promotes the extraction of electrons e ⁻ from the n-type semiconductor layer 26. As a molecule | numerator which has an electric dipole moment, the molecule | numerator shown by following General formula (2) can be mentioned.

XAY ¹ (2)
Incidentally, the X, A, and, ^{Y 1} is omitted both, X in the general formula (1) shown in Embodiment 1, A, and is the same as ^{Y 1,} the description here.

On the other hand, the p-type extraction improving layer 50P for promoting the extraction of holes h ⁺ from the p-type semiconductor layer 16 and the n-type injection improving layer 40N for promoting the injection of e ⁻ into the n-type semiconductor layer 26 can be used. As a molecule | numerator which has a dipole moment, the molecule | numerator shown by following General formula (3) can be mentioned, for example.

XAY ² (3)
Incidentally, X, A, and, for ^{Y 2} is omitted, X in the general formula (1) shown in Embodiment 1, A, and is the same as ^{Y 2,} the description here.

(Organic semiconductor layer)
The organic semiconductor layer can be formed of a conventionally known organic semiconductor material having p-type characteristics or n-type characteristics. Examples of the p-type organic semiconductor material that forms the p-type semiconductor layer 16 include pentacene, rubrene, oligothiophene, polythiophene, and alkyl substitution products thereof. Among these, pentacene is preferable because of high carrier mobility.

On the other hand, examples of the n-type organic semiconductor material forming the n-type semiconductor layer 26 include C ₆₀ fullerene, fluorinated pentacene, and a perylene imide compound. Among these, C ₆₀ fullerene is preferable because of high carrier mobility.

(Electrode material)
Since the electrode materials for forming the

gate electrodes

12 and 22, the

source electrodes

14 and 24, and the

drain electrodes

15 and 25 are the same as those in the first embodiment, the description thereof is omitted here.

Note that in the conventional complementary logic circuit configured by combining a plurality of organic transistors, in order to improve switching characteristics, the constituent material of one source electrode and drain electrode is changed to the configuration of the other source electrode and drain electrode. It is necessary to use a material having a work function larger than that of the material.

On the other hand, in the semiconductor device 10, an injection improvement layer or an extraction improvement layer suitable for the traveling direction of carriers is provided between each source electrode and each drain electrode and the organic semiconductor layer, thereby promoting carrier injection and carrier extraction. I am letting. Therefore, the source electrode 14 and the drain electrode 15, and the source electrode 24 and the drain electrode 25 can be formed using the same electrode material. Even if they are all formed of the same electrode material, the characteristics of the semiconductor device 10 and each of the organic transistors P1 and N1 are not deteriorated as will be described later.

FIG. 9 is a diagram showing a film formation pattern of each source electrode and each drain electrode. When the semiconductor device 10 is manufactured, since the same electrode material can be used for each electrode, as shown in FIG. 9, one source electrode 14 and drain electrode 15, and the other source electrode 24 and drain electrode 25 can be formed by using existing photolithography in the same process.

(2) Manufacturing Method of Semiconductor Device Next, a manufacturing method of the organic transistor according to this embodiment having the above-described configurations will be described.

Also in the present embodiment, as in the first embodiment, after forming the source electrode and the drain electrode, a material composed of a composition that constitutes the injection improving layer is laminated on both the source electrode and the drain electrode, The injection improving layer and the extraction improving layer are realized by adopting a characteristic method of forming the extraction improving layer by modifying a part of the material layer.

FIG. 10 is a diagram showing a method for manufacturing the organic transistor of the present embodiment.

(First step: Gate electrode / gate insulating layer forming step)
Note that the gate electrode / gate insulating layer forming step shown in FIG. 10A is substantially the same as that of the first embodiment, and thus the description thereof is omitted.

(Second step: source / drain electrode forming step)
In the source / drain electrode formation step shown in FIG. 10B, the above-described source / drain electrode material is formed on the gate insulating layer 13 by patterning using existing photolithography. In Example 4 to be described later, the source electrode 14 of the p-type transistor P1, the drain electrode 15 of the p-type transistor P1, the drain electrode 25 of the n-type transistor N1, and the source electrode 24 of the n-type transistor N1 are all 5 nm chromium. In addition, a structure made of 60 nm of gold is formed in the same process by photolithography.

Note that the drain electrode 15 of the p-type transistor P1 and the drain electrode 25 of the n-type transistor N1 are electrically connected.

(Third step: Improvement layer forming step)
Next, as shown in FIG. 10C, on the formed source electrode / drain electrode, as an improvement layer 17 (material layer), layers (SAMs) made of a material having a composition constituting the injection improvement layer are formed. Form. Since the formation method of the improvement layer 17 is the same as that of Embodiment 1, description here is abbreviate | omitted.

(Fourth step: partial modification step by photoreduction reaction)
Next, as shown in FIG. 10D, the modification (conversion) process is performed only on the improvement layer 17 formed on the drain electrode 15 of the p-type transistor P1 and the source electrode 24 of the n-type transistor N1. Then, an implantation improvement layer 40P of the p-type transistor P1 and an extraction improvement layer 50N of the n-type transistor N1 are formed.

For example, in Example 4 to be described later, a monomolecular film made of p-nitrobenzenethiol is formed as the improvement layer 17, and the improvement layer on the drain electrode 15 of the p-type transistor P1 and the source electrode 24 of the n-type transistor N1. 17 is irradiated with light of 514.5 nm in an air atmosphere, the nitro group on the surface of the improvement layer 17 can be converted into an amino group. The conversion of the nitro group to the amino group can be confirmed by atmospheric photoelectron spectroscopy and XPS.

Here, the photoreduction reaction is an electrode on which an improvement layer 17 is formed, and electrons generated by light irradiation on the electrode material reduce functional groups exposed on the surface of the improvement layer 17. It is a chemical reaction that converts to another functional group.

At this time, the photoirradiation may be performed using a photomask in which only the improvement layer 17 on the drain electrode 15 is optically empty. In addition, the light irradiation method described in Embodiment 1 can be used.

The light to be irradiated may be light having a wavelength in the range of 180 to 600 nm, and the irradiation can be performed in an air atmosphere. In Example 4 to be described later, an argon ion laser of 514.5 nm is irradiated for 5 minutes in an air atmosphere.

The irradiation conditions can be performed in the same manner as in the first embodiment.

(Fifth step: Organic semiconductor layer formation step)
Next, as shown in FIG. 10G, a p-type semiconductor layer 16 is formed to form a p-type organic transistor P1, and an n-type semiconductor layer 26 is formed to form an n-type organic transistor N1. To do. As the method for forming the p-type semiconductor layer 16 and the n-type semiconductor layer 26, the method described in Embodiment 1 can be used, and thus the description thereof is omitted here.

Through the above steps, a semiconductor device having a CMOS structure can be manufactured.

(Characteristics of semiconductor devices)
The characteristics of the semiconductor device obtained by the above method are that both the p-type transistor P1 and the n-type transistor N1 have good mobility and ON / OFF ratio, the source electrode / organic semiconductor layer interface, and the organic semiconductor layer / drain electrode interface. The contact resistance can be suppressed to be lower than that of an element having no injection improvement layer and no extraction improvement layer. Details are described in Example 4 to be described later.

(Operational effect of the fourth embodiment)
As described above, according to the manufacturing method of the present embodiment, after the source electrode and the drain electrode are simultaneously formed, the improvement layer 17 in which the direction of the electric dipole moment is the same on all the source electrodes and the drain electrodes. Further, the improvement layer 17 formed on the drain electrode 15 of the p-type transistor P1 and the source electrode 24 of the n-type transistor N1 in the improvement layer 17 is subjected to a photoreduction reaction. By reversing the direction of the electric dipole moment and separately forming the injection improvement layer and the extraction improvement layer, a fine electrode pattern can be formed. In detail, before forming the injection improving layer and extracts improving layer, by forming the source electrode and the drain electrode, using process (e.g., photolithography) of damage to the injection improving layer and extracts improving layer is expected It is possible to make the electrodes finer by using the above process.

Further, as described with reference to FIG. 10, patterning by light irradiation with high directivity and high resolution is possible by performing the partial modification process using a chemical reaction by light irradiation. Furthermore, since the direction of the electric dipole moment can be reversed in a single step of light irradiation, the number of steps is reduced.

In this embodiment, the reduction reaction using light irradiation has been described as the partial modification step. However, the present invention is not limited to this, and the step may be performed by an oxidation reaction by light irradiation. . In this case, the material for the material layer may be selected from materials that can cause an oxidation reaction (photo-oxidation reaction) by light irradiation and reverse the direction of the electric dipole moment.

[Embodiment 5]
The manufacturing method according to the present invention can also be adopted in a so-called TFT array manufacturing method in which a plurality of TFT elements are connected by wiring as shown in FIG.

For example, first, as shown in FIG. 11A, the source electrode of each TFT element is connected to a so-called source bus line and is electrically disconnected from the drain electrode. Next, an improvement layer that is a monomolecular film is formed on the source electrode and the drain electrode, and the improvement layer formed on one of the source electrode and the drain electrode is modified to convert the functional group, Reverse the direction of the electric dipole moment. As an example, as in FIG. 5, a monomolecular film (improvement layer 17 in FIG. 11B) made of p-aminobenzenethiol is formed on the source / drain electrode, and the amino layer of the improvement layer 17 on the source electrode is formed. The group is oxidized and converted into the injection improving layer 40 in which the nitro group is exposed on the surface (FIG. 11C).

(Operational effect of the fifth embodiment)
As described above, according to the manufacturing method of the present embodiment, it becomes possible to oxidize only the improvement layer formed on the source electrode or the drain electrode of the TFT connected to each source bus line in a batch, It becomes possible to easily manufacture TFT arrays having different dipole moment directions on the source / drain electrodes.

[Embodiment 6]
The manufacturing method according to the present invention can also be employed in a method for manufacturing a top gate transistor. FIG. 12 is a cross-sectional view showing the configuration of the organic transistor of this embodiment. As shown in FIG. 12, the organic transistor 2 includes a substrate 11, a source electrode 14 and a drain electrode 15 formed on the substrate 11, and an injection improvement layer disposed between the source electrode 14 and the organic semiconductor layer 16. 40, an extraction improvement layer 50 disposed between the drain electrode 15 and the organic semiconductor layer 16, a gate insulating layer 13 in contact with the organic semiconductor layer 16, and a gate electrode 12 in contact with the gate insulating layer 13. ing. Incidentally, including the Fig. 12, the configuration of organic transistor shown in this invention, the source-drain electrode is in contact with the underlying organic semiconductor layer, it is a so-called bottom contact type, source and drain electrodes of the organic semiconductor layer It may be a top contact type in contact with the upper part.

The organic transistor of this embodiment can be manufactured as follows.

Forming a source electrode and a drain electrode on a substrate so as to be spaced apart from each other; forming a material layer made of a material or molecule having an electric dipole moment on the source electrode and the drain electrode; and Reversing the direction of the electric dipole moment from the negative electrode to the positive electrode of the material layer or material of the material layer formed on the drain electrode or the material layer formed on the drain electrode, on the source electrode A step of providing an injection improving layer for promoting the movement of charges and an extraction improving layer for promoting the movement of charges on the drain electrode, the direction of the electric dipole moment being opposite to that of the injection improving layer. Forming an organic semiconductor layer in contact with the injection improving layer and the extraction improving layer, and forming a gate insulating layer in contact with the organic semiconductor layer. It can be made from it and forming a gate electrode in contact with the gate insulating layer.

In the step of reversing the direction of the electric dipole moment, an oxidation reaction or a reduction reaction is performed on the material layer formed on the source electrode or the material layer formed on the drain electrode. A reaction of any one of photochemical reaction, photooxidation reaction, and photoreduction reaction, or a combination of a plurality of these reactions, and the electric dipole moment of the material layer is increased. Invert the direction.

Specific component members and formation methods of each layer can be manufactured by adopting the above-described Embodiments 1 to 4, respectively.

In addition, this invention is not limited to each embodiment mentioned above. Those skilled in the art can make various modifications to the present invention within the scope of the claims. That is, a new embodiment can be obtained by combining appropriately changed technical means within the scope of the claims. That is, the specific embodiments made in the section of the detailed description of the invention are merely to clarify the technical contents of the present invention, and are limited to such specific examples and are interpreted narrowly. It should be understood that the invention can be practiced with various modifications within the spirit of the invention and within the scope of the following claims.

(Summary of the present invention)
The present invention has been made in view of the above problems, and an object of the present invention is to provide an organic semiconductor device manufacturing method capable of selectively making different monomolecular films by a simple method. The purpose is to provide.

That is, the manufacturing method of the organic semiconductor device according to the present invention is to solve the above problems,
A first step of forming a gate electrode and a gate insulating layer on the substrate;
A second step in which the source electrode and the drain electrode are separated from each other and formed on the gate insulating layer formed by the first step;
A third step of forming a material layer made of a material or molecule having an electric dipole moment on the source electrode and the drain electrode;
Reversing the direction of the electric dipole moment from the negative electrode to the positive electrode of the material layer or material of the material layer formed on the source electrode or the material layer formed on the drain electrode, the source electrode An extraction improvement layer for promoting charge transfer is provided on the drain electrode, and an extraction improvement layer for promoting charge transfer, wherein the direction of the electric dipole moment is opposite to that of the injection improvement layer on the drain electrode. A fourth step of providing
And a fifth step of forming an organic semiconductor layer in contact with the injection improving layer and the extraction improving layer.

Specifically, in the fourth step, the material layer formed on the source electrode or the material layer formed on the drain electrode is oxidized, reduced, photochemically reacted, A reaction of any one of a photooxidation reaction and a photoreduction reaction, or a combination of a plurality of these reactions is caused to reverse the direction of the electric dipole moment of the material layer. .

Moreover, in addition to said structure, the manufacturing method of the organic-semiconductor device based on this invention,
The fourth step, the material layer is formed on the source electrode, or, with respect to the material layer formed on the drain electrode, and photochemical reactions, followed by condensation reaction, addition reaction, or , Causing any one of the substitution reactions to reverse the direction of the electric dipole moment of the material layer.

According to the above configuration, only one electric dipole moment can be reversed with high accuracy. More specifically, although photochemical reaction is used, patterning with light generally has high directivity and local patterning is possible, so that the resolution can be increased.

Moreover, in addition to said structure, the manufacturing method of the organic-semiconductor device based on this invention,
In the third step, it is preferable to form a self-assembled monolayer or a self-assembled molecular layer laminated film in which self-assembled molecular layers are laminated as the material layer.

As a method for forming the injection improving layer and the extraction improving layer, if the method is to form a self-assembled monolayer or a self-assembled molecular layer laminated film, the electric dipole moment is reduced at a low temperature of 150 ° C. or lower and atmospheric pressure. Since it is possible to form a layer with a holding property, it is possible to reduce deterioration and damage to the thermoplastic plastic substrate.

Moreover, in addition to said structure, the manufacturing method of the organic-semiconductor device based on this invention,
The fourth step, the material layer is formed on the source electrode, or, with respect to the material layer formed on the drain electrode, thereby causing a photochemical reaction, the electric dipole of the material layer It is a process to reverse the direction of the child moment,
In the third step, a molecule having a benzene ring and a chloromethyl group is self-assembled monolayer or self-assembled molecular layer so that the chloromethyl group is exposed on the side opposite to the source electrode and the drain electrode. Forming the material layer by forming a self-assembled molecular layer laminated film laminated with
In the fourth step,
A step of converting to an aldehyde group by the photochemical reaction of the chloromethyl group;
By condensation reaction of the converted aldehyde group and one of aromatic or aliphatic diamine, the amino group is exposed on the opposite side of the source electrode or the drain electrode, and the electric dipole moment of the material layer And a step of reversing the direction of the.

According to the above configuration, only one electric dipole moment can be reversed with high accuracy. More specifically, although photochemical reaction is used, patterning with light generally has high directivity and local patterning is possible, so that the resolution can be increased. The aromatic diamine does not cause a chemical reaction with the chloromethyl group but selectively causes a chemical reaction with the aldehyde group. As a result, only those having an aldehyde group exposed form an imine bond, and an aromatic diamine is laminated on the monomolecular film.

Moreover, the manufacturing method of the organic semiconductor device according to the present invention is replaced with the above configuration,
In the fourth step, the material layer formed on the source electrode or the material layer formed on the drain electrode is caused to undergo an oxidation reaction, so that the electric bipolar electrode of the material layer is formed. It is a process to reverse the direction of the child moment,
In the third step, a molecule having an benzene ring and an amino group, or an ethylene group in the benzene ring or an alkyl main chain skeleton, the amino group or the ethylene group is exposed on the side opposite to the source electrode and the drain electrode. Forming the material layer by forming a self-assembled monolayer film or a self-assembled molecular layer laminated film in which self-assembled molecular layers are laminated,
In the fourth step, the nitro group generated by the oxidation reaction of the amino group or the carboxyl group generated by the oxidation reaction of the ethylene group is exposed on the opposite side of the source electrode or the drain electrode, and the material layer It is preferable to reverse the direction of the electric dipole moment.

According to the above configuration, the dipole moment can be reversed in one process, and the number of steps can be reduced.

Moreover, the manufacturing method of the organic semiconductor device according to the present invention is replaced with the above configuration,
In the fourth step, the material layer formed on the source electrode or the material layer formed on the drain electrode is caused to undergo a reduction reaction, so that the electric bipolar electrode of the material layer is formed. It is a process to reverse the direction of the child moment,
In the third step, a benzene ring and a nitro group, or a molecule having a carbonyl group in the benzene ring or alkyl main chain skeleton, the nitro group or the carbonyl group is exposed on the side opposite to the source electrode and the drain electrode. Forming the material layer by forming a self-assembled monolayer film or a self-assembled molecular layer laminated film in which self-assembled molecular layers are laminated,
In the fourth step, an amino group generated by the reduction reaction of the nitro group or a hydroxyl group generated by the reduction reaction of the carbonyl group is exposed on the opposite side of the source electrode or the drain electrode, and the material layer It is preferable to reverse the direction of the electric dipole moment.

Moreover, the manufacturing method of the organic semiconductor device according to the present invention is replaced with the above configuration,
In the fourth step, the material layer formed on the source electrode or the material layer formed on the drain electrode is caused to undergo a photoreduction reaction, so that the electrical property of the material layer is increased. A process of reversing the direction of the dipole moment,
In the third step, a molecule having a benzene ring and a nitro group is laminated with a self-assembled monolayer or a self-assembled molecular layer so that the nitro group is exposed on the opposite side of the source and drain electrodes. Forming the material layer by forming a self-assembled molecular layer laminate film,
In the fourth step, as the photoreduction reaction, an electron is induced in the electrode material of the source electrode or the drain electrode by light irradiation, the nitro group is reduced by the reduction reaction, and the amino group is converted into a source electrode or It is preferable to reverse the direction of the electric dipole moment of the material layer exposed on the opposite side of the drain electrode.

According to the above configuration, only one electric dipole moment can be reversed with high accuracy. More specifically, although photochemical reaction is used, patterning with light generally has high directivity and local patterning is possible, so that the resolution can be increased. Furthermore, since the direction of the electric dipole moment can be reversed in a single step of light irradiation, the number of steps is reduced.

Moreover, in addition to said structure, the manufacturing method of the organic-semiconductor device based on this invention,
The fourth step is a step of causing the oxidation reaction,
The oxidation reaction is preferably caused by a voltage applied between the source electrode or the drain electrode and a probe of a scanning probe microscope.

According to the above configuration, it is possible to selectively reverse the direction of the electric dipole moment in a fine region at the nano level by performing an oxidation reaction with a probe of a scanning probe microscope.

Moreover, in addition to said structure, the manufacturing method of the organic-semiconductor device based on this invention,
The fourth step is a step of causing the reduction reaction,
The reduction reaction is preferably caused by a voltage applied between the source electrode or the drain electrode and a probe of a scanning probe microscope.

According to the above configuration, it is possible to selectively reverse the direction of the electric dipole moment in a fine region at the nano level by performing a reduction reaction with a probe of a scanning probe microscope.

Moreover, in addition to said structure, the manufacturing method of the organic-semiconductor device based on this invention,
The fourth step is a step of causing the oxidation reaction,
The oxidation reaction is preferably caused by a voltage applied between the source electrode or the drain electrode and a counter electrode in contact with the source electrode or the drain electrode through the electrolyte solution.

According to the above configuration, since the entire surface of the desired source electrode or drain electrode can be caused to oxidize or reduce at a time, the process time is shortened.

Moreover, in addition to said structure, the manufacturing method of the organic-semiconductor device based on this invention,
The fourth step is a step of causing the reduction reaction,
The reduction reaction is preferably caused by a voltage applied between the source electrode or the drain electrode and a counter electrode in contact with the source electrode or the drain electrode via an electrolyte solution.

Moreover, in order to solve said subject, the manufacturing method of the other organic-semiconductor device based on this invention,
A method of manufacturing an organic semiconductor device having a p-type organic transistor and an n-type organic transistor,
A first step of forming a gate insulating layer on the gate electrode;
a second step of forming a source electrode and a drain electrode constituting the p-type organic transistor and a source electrode and a drain electrode constituting the n-type organic transistor on the gate insulating layer;
A third step of forming a material layer made of a material or molecule having an electric dipole moment on the source electrode and the drain electrode;
The material layer above the source electrode of the p-type organic transistor and the material layer above the drain electrode of the n-type organic transistor, or the material layer above the drain electrode of the p-type organic transistor and the source of the n-type organic transistor The material of the material layer on the electrode or the direction of the electric dipole moment from the negative electrode to the positive electrode of the molecule is reversed, and the p-type injection improving layer and the n-type organic transistor are formed on the source electrode of the p-type organic transistor. A fourth type in which an n-type extraction improvement layer is provided on the drain electrode, a p-type extraction improvement layer is provided on the drain electrode of the p-type organic transistor, and an n-type injection improvement layer is provided on the source electrode of the n-type organic transistor. Process,
and a fifth step of forming an organic semiconductor layer in contact with the injection improving layer and the extraction improving layer of the p-type organic transistor and an organic semiconductor layer in contact with the injection improving layer and the extraction improving layer of the n-type organic transistor. It is characterized by.

Specifically, the material layer on the source electrode of the p-type organic transistor and the material layer on the drain electrode of the n-type organic transistor, or the material layer and n on the drain electrode of the p-type organic transistor Any of the oxidation reaction, reduction reaction, photochemical reaction, photooxidation reaction, and photoreduction reaction, or a plurality of these reactions on the material layer on the source electrode of the organic transistor It is preferable to cause a reaction combining these reactions to reverse the direction of the electric dipole moment of the material layer.

Moreover, in addition to said structure, the manufacturing method of the organic-semiconductor device based on this invention,
In the second step, the source electrode and the drain electrode are preferably formed using the same material.

According to the above configuration, the source electrode and the drain electrode can be formed in the same process.

Hereinafter, the organic transistor of the present invention will be described in more detail using examples.

[Example 1: Example of configuration described in Embodiment 1]
In this example, an organic transistor was produced and evaluated based on the production method shown in FIG.

First, as a step of forming a gate electrode and a gate insulating layer, as shown in FIG. 3A, aluminium is formed as a gate electrode 12 on a glass substrate 11 (substrate size 25 mm × 25 mm) by sputtering through a metal mask. After forming the film with a thickness of 60 nm, silicon nitride was formed as the gate insulating layer 13 with a thickness of 200 nm through a metal mask.

Next, as a source electrode and drain electrode formation step, as shown in FIG. 3B, ITO 60 nm was formed by patterning by existing photolithography, and the source electrode 14 and the drain electrode 15 were formed. The channel length at this time was 2, 4, 6, 10, 20 μm, and the channel width was 1000 μm. Specifically, a negative photoresist is applied on the gate insulating layer, and the portions other than the electrode forming portion are exposed. In order to cure the resist, the substrate was heated and developed to prepare a substrate on which the resist was formed in addition to the electrode forming portion. Furthermore, ITO was deposited to 60 nm by sputtering, and the resist other than the electrode forming portion was peeled off by lift-off to obtain a source / drain electrode.

Next, as an improved layer forming step, as shown in FIG. 3C, SAMs of p-chloromethylphenyltrimethoxysilane as the improved layer 17 were formed on the source electrode and the drain electrode. As a forming method, p-chloromethylphenyltrimethoxysilane and a substrate formed with a source electrode and a drain electrode were sealed in a heat-resistant container and heated in an oven at 150 ° C. for 3 hours. Further, the improvement layer 17 was formed on the source electrode and the drain electrode by removing the excessively adsorbed p-chloromethylphenyltrimethoxysilane by immersing the substrate in acetone, stirring and washing.

Next, as a partial modification step, as shown in FIGS. 3D and 3E, only the drain electrode was photochemically reacted to convert the chloromethyl group into an aldehyde group. Specifically, first, the p-chloromethylphenyl skeleton on the drain electrode is irradiated with light at 193 nm in an air atmosphere for 1 minute through a photomask in which only the drain electrode formation region is opened. Converted. In this way, the surface of the improvement layer 17 on the drain electrode 15 was converted into an aldehyde group using light irradiation.

Next, as shown in FIG. 3 (f), the amino group is exposed on the surface of the drain electrode by chemically reacting with the aldehyde group exposed on the surface of the drain electrode and one amino group of 1,4-phenylenediamine. I let you. Details were as follows. A substrate with an aldehyde group exposed on the surface of the drain electrode is immersed in a 1 mM absolute ethanol solution of 1,4 phenylenediamine for 12 hours to form an imine bond, and the improvement layer 17 on the drain electrode is subjected to 1,4 phenylene. Diamine was laminated to expose the amino group on the drain electrode. By the above method, the functional group exposed on the surface was converted from a chloromethyl group to an amino group, thereby forming an improved layer in which the electric dipole moment vector was inverted on the drain electrode.

As described above, the injection improving layer 40 having a dipole moment from the organic semiconductor layer toward the source electrode is formed on the source electrode 14, and on the drain electrode 15, from the drain electrode to the organic semiconductor layer. An extraction improvement layer 50 having a directed dipole moment was formed.

Next, as an organic semiconductor layer forming step, as shown in FIG. 3G, the pentacene as the organic semiconductor layer 16 is 60 nm so as to come into contact with the implantation improvement layer and the extraction improvement layer through the metal mask. Formed by vacuum evaporation.

When the characteristics of the organic transistor obtained by the above manufacturing method were evaluated, the mobility was 0.3 cm ² / V · s, and the ON / OFF ratio was 10 ^6, which was a favorable value. Further, when the contact resistance of the source electrode / organic semiconductor interface and the organic semiconductor layer / drain electrode interface was evaluated, it was compared with the organic transistor of Comparative Example 1 which was prepared as a comparative example and did not have an injection improvement layer and an extraction improvement layer. The contact resistance decreased to 1/3.

[Example 2: Example of configuration described in Embodiment 2]
Since the major difference between the present embodiment and the first embodiment is only the modification process, other portions will be briefly described.

In the present embodiment, it the substrate 11 is glass, the gate electrode 12 to turn vacuum deposited over the aluminum, the gate insulating layer 13 is silicon dioxide, the metal mask gold on the source electrode 14 and the gate electrode 15 of chromium The organic semiconductor layer 16 is a C ₆₀ fullerene, the injection improving layer 40 and the extraction improving layer 50 are a monomolecular film made of p-aminobenzenethiol and a monomolecular film made of p-nitrobenzenethiol, respectively.

In this embodiment, only the improvement layer 17 formed on the drain electrode 15 of the improvement layer 17 formed on the source electrode 14 and the drain electrode 15 oxidizes the amino group exposed on the surface thereof, Converted to the base. Specifically, an amino group exposed on the surface of the improvement layer 17 is oxidized using an atomic force microscope (AFM) and converted to a nitro group. Specifically, by using an AFM probe coated with gold, a voltage of +3 V is applied to the drain electrode, and the oxidation reaction is performed by scanning the improvement layer 17 in the atmosphere. Was performed ((c) of FIG. 4). Thereby, the extraction improving layer 50 was formed on the drain electrode 15.

When the characteristics of the organic transistor obtained by the above production method were evaluated, the mobility was about 0.7 cm ² / V · s, and the ON / OFF ratio was about 10 ⁶ , showing relatively good values.

Further, the contact resistance at the interface between the source electrode / organic semiconductor layer and the interface between the organic semiconductor layer / drain electrode is about １／ that of the element having no injection improvement layer and no extraction improvement layer prepared in Comparative Example 1 below. became. That is, a contact resistance can be lowered by forming an injection improvement layer and an extraction improvement layer on the source electrode and the drain electrode, respectively.

[Example 3: Example of configuration described in Embodiment 3]
Since the major difference between the present embodiment and the first embodiment is only the modification process, other portions will be briefly described.

In this embodiment, the substrate 11 is made of glass, the gate electrode 12 is made of aluminum, the gate insulating layer 13 is made of silicon dioxide, the source electrode 14 and the gate electrode 15 are made of chromium on a chromium in order through a metal mask. The organic semiconductor layer 16 is pentacene, the injection improving layer 40 and the extraction improving layer 50 are each a monomolecular film made of p-nitrobenzenethiol and a monomolecular film made of p-aminobenzenethiol.

In this embodiment, only the improvement layer 17 formed on the drain electrode 15 of the improvement layer 17 formed on the source electrode 14 and the drain electrode 15 oxidizes the nitro group exposed on the surface thereof, Converted to the base. Specifically, using an atomic force microscope (AFM), a voltage of −3 V is applied in the atmosphere between the probe needle and the drain electrode, and scanning is performed, so that the nitro exposed on the surface of the improvement layer 17 is exposed. The group is reduced and converted to an amino group ((c) in FIG. 6). Thereby, the extraction improving layer 50 was formed on the drain electrode 15.

When the characteristics of the organic transistor obtained by the above production method were evaluated, the mobility was about 0.5 cm ² / V · s, and the ON / OFF ratio was about 10 ⁶ , showing relatively good values.

Further, the contact resistance at the interface between the source electrode / organic semiconductor layer and the interface between the organic semiconductor layer / drain electrode is about １／ that of the device having no injection improvement layer and no extraction improvement layer prepared in Comparative Example 1 below. became. That is, a contact resistance can be lowered by forming an injection improvement layer and an extraction improvement layer on the source electrode and the drain electrode, respectively.

[Example 4: Example of configuration described in Embodiment 4]
In the fourth embodiment, the semiconductor device shown in FIG. 7 is manufactured.

First, the aluminum 60nm after forming on the entire surface by sputtering as the gate electrode 12 on the glass substrate 11 (substrate size 25 mm × 25 mm), using existing photolithography, a pattern was formed. Next, 200 nm of silicon dioxide was formed as the gate insulating layer 13 by sputtering.
As p-type source electrode 14, p-type drain electrode 15, n-type drain electrode 25, n-type source electrode, chromium 5 nm, silver 60 nm, it was formed in the same step by photolithography (in Figure 10 (b)). Note that the p-type drain electrode and the n-type drain electrode are electrically connected.

Subsequently, a monomolecular film made of p-nitrobenzenethiol is formed as an improvement layer 17 on all the source / drain electrodes (FIG. 10 (c)), on the drain electrode 15 of the p-type transistor P1, and n The improvement layer 17 on the source electrode 24 of the n-type transistor N1 is irradiated with light of 514.5 nm with an argon ion laser in an air atmosphere, thereby converting the nitro group on the surface of the improvement layer 17 into an amino group ( (D) of FIG.

Finally, as the p-type organic semiconductor layer 16, pentacene was formed to 60 nm by vacuum vapor deposition through a metal mask to form a p-type transistor P1. Then the n-type organic semiconductor layer _26, the _{C 60} fullerene, and 60nm formed by vacuum deposition through a metal mask to form an n-type transistor element N1. The CMOS of Example 4 was fabricated through the above steps ((e) in FIG. 10).

When the characteristics of the semiconductor device having a CMOS structure obtained by the above manufacturing method were evaluated, the p-type transistor P1 has a mobility of about 0.8 cm ² / V · s, an ON / OFF ratio of about 10 ⁶ , and an n-type. The transistor N1 had a mobility: about 0.7 cm ² / V · s, an ON / OFF ratio of about 10 ⁶ , and showed a relatively good value.

In addition, the p-type transistor P1 of this embodiment has a contact resistance that is the same as that of the fourth embodiment except that it does not have an implantation improvement layer and an extraction improvement layer. Compared to the p-type transistor of the comparative configuration, it was 1/10 times, and the n-type transistor N1 of this example was 1/5 times that of the n-type transistor of the comparative configuration.

[Comparative example]
FIG. 13 shows the structure of an organic transistor manufactured in a comparative example.

In this comparative example, the gate electrode 212 and the gate insulating layer 213 were formed on the glass substrate 211 by the same material and manufacturing method as in the example. Next, gold was formed to a thickness of 60 nm as a source electrode 214 and a drain electrode 215 through a metal mask. Next, pentacene was formed as the organic semiconductor layer 216 with a film thickness of 60 nm using vacuum vapor deposition to manufacture an organic transistor. That is, the organic transistor of this comparative example does not include any improvement layer.

Evaluation of the properties of the organic transistor of the present comparative example, the mobility 0.1cm ² / V · s, was ON / OFF ratio of 10 ^5.

The present invention can be optimally used as a field effect transistor mounted on various semiconductor devices and has high industrial applicability.

DESCRIPTION OF SYMBOLS 1 Organic transistor 10 Semiconductor device 11 Substrate 12 Gate electrode 13 Gate insulating layer 14 Source electrode 14 (p type) Source electrode 15 (p type) Drain electrode 16 (p type) Organic semiconductor layer 17 Improvement layer (material layer)
22 gate electrode 24 (n-type) source electrode 25 (n-type) drain electrode 26 (n-type) organic semiconductor layer 40 injection improvement layer 40N n-type injection improvement layer 40P p-type injection improvement layer 50 extraction improvement layer 50N n-type extraction improvement Layer 50P p-type extraction improving layer 60 electrolyte solution 61 counter electrode N1 n-type transistor P1 p-type transistor

Claims

A method for manufacturing an organic semiconductor device, comprising:
A first step of forming a gate electrode and a gate insulating layer on the substrate;
A second step in which the source electrode and the drain electrode are separated from each other and formed on the gate insulating layer formed by the first step;
A third step of forming a material layer made of a material or molecule having an electric dipole moment on the source electrode and the drain electrode;
Reversing the direction of the electric dipole moment from the negative electrode to the positive electrode of the material layer or material of the material layer formed on the source electrode or the material layer formed on the drain electrode, the source electrode An extraction improvement layer for promoting charge transfer is provided on the drain electrode, and an extraction improvement layer for promoting charge transfer, wherein the direction of the electric dipole moment is opposite to that of the injection improvement layer on the drain electrode. A fourth step of providing
And a fifth step of forming an organic semiconductor layer in contact with the injection improving layer and the extraction improving layer.
In the fourth step, the material layer formed on the source electrode or the material layer formed on the drain electrode is subjected to an oxidation reaction, a reduction reaction, a photochemical reaction, a photooxidation reaction, and A reaction of any one of the photoreduction reactions, or a combination of a plurality of these reactions, to reverse the direction of the electric dipole moment of the material layer. The manufacturing method of the organic-semiconductor device of Claim 1.
In the fourth step, the photochemical reaction and subsequent condensation reaction, addition reaction, or the material layer formed on the source electrode or the material layer formed on the drain electrode 3. The method of manufacturing an organic semiconductor device according to claim 1, wherein any one of substitution reactions is caused to reverse the direction of the electric dipole moment of the material layer.
3. In the third step, as the material layer, a self-assembled monolayer or a self-assembled molecular layer laminated film in which self-assembled molecular layers are laminated is formed. The manufacturing method of the organic-semiconductor device of description.
In the fourth step, the material layer formed on the source electrode or the material layer formed on the drain electrode is caused to undergo a photochemical reaction so that the electric bipolar electrode of the material layer is formed. It is a process to reverse the direction of the child moment,
In the third step, a molecule having a benzene ring and a chloromethyl group is self-assembled monolayer or self-assembled molecular layer so that the chloromethyl group is exposed on the side opposite to the source electrode and the drain electrode. Forming the material layer by forming a self-assembled molecular layer laminated film laminated with
In the fourth step,
A step of converting to an aldehyde group by the photochemical reaction of the chloromethyl group;
By condensation reaction of the converted aldehyde group and one of aromatic or aliphatic diamine, the amino group is exposed on the opposite side of the source electrode or the drain electrode, and the electric dipole moment of the material layer 5. The method for manufacturing an organic semiconductor device according to claim 1, further comprising a step of reversing the direction of.
In the fourth step, the material layer formed on the source electrode or the material layer formed on the drain electrode is caused to undergo an oxidation reaction, so that the electric bipolar electrode of the material layer is formed. It is a process to reverse the direction of the child moment,
In the third step, a molecule having an benzene ring and an amino group, or an ethylene group in the benzene ring or an alkyl main chain skeleton, the amino group or the ethylene group is exposed on the side opposite to the source electrode and the drain electrode. Forming the material layer by forming a self-assembled monolayer film or a self-assembled molecular layer laminated film in which self-assembled molecular layers are laminated,
In the fourth step, the nitro group generated by the oxidation reaction of the amino group or the carboxyl group generated by the oxidation reaction of the ethylene group is exposed on the opposite side of the source electrode or the drain electrode, and the material layer The method of manufacturing an organic semiconductor device according to any one of claims 1 to 4, wherein the direction of the electric dipole moment is reversed.
In the fourth step, the material layer formed on the source electrode or the material layer formed on the drain electrode is caused to undergo a reduction reaction, so that the electric bipolar electrode of the material layer is formed. It is a process to reverse the direction of the child moment,
In the third step, a benzene ring and a nitro group, or a molecule having a carbonyl group in the benzene ring or alkyl main chain skeleton, the nitro group or the carbonyl group is exposed on the side opposite to the source electrode and the drain electrode. Forming the material layer by forming a self-assembled monolayer film or a self-assembled molecular layer laminated film in which self-assembled molecular layers are laminated,
In the fourth step, an amino group generated by the reduction reaction of the nitro group or a hydroxyl group generated by the reduction reaction of the carbonyl group is exposed on the opposite side of the source electrode or the drain electrode, and the material layer The method of manufacturing an organic semiconductor device according to claim 1, wherein the direction of the electric dipole moment is reversed.
In the fourth step, the material layer formed on the source electrode or the material layer formed on the drain electrode is caused to undergo a photoreduction reaction, so that the electrical property of the material layer is increased. A process of reversing the direction of the dipole moment,
In the first and third step, the molecules having a benzene ring and the nitro group, the self-assembled monolayer to the nitro group is exposed on the opposite side of the source electrode and the drain electrode, or laminated self-assembled molecule layer Forming the material layer by forming a self-assembled molecular layer laminate film,
In the fourth step, as the photoreduction reaction, electrons are induced in the electrode material of the source electrode or the drain electrode by light irradiation, the nitro group is reduced by the reduction reaction, and the amino group is converted into a source electrode or 5. The method of manufacturing an organic semiconductor device according to claim 1, wherein the direction of the electric dipole moment of the material layer is inverted by being exposed on the opposite side of the drain electrode. 6.
The fourth step is a step of causing the oxidation reaction,
The oxidation reaction is the production of organic semiconductor device according to claim 2 or 6, characterized in that caused by a voltage applied between the the source electrode or the drain electrode, the probe of the scanning probe microscope Method.
The fourth step is a step of causing the reduction reaction,
8. The method of manufacturing an organic semiconductor device according to claim 2, wherein the reduction reaction is caused by a voltage applied between the source electrode or the drain electrode and a probe of a scanning probe microscope. Method.
The fourth step is a step of causing the oxidation reaction,
The oxidation reaction, and the source electrode or the drain electrode, claim 2, characterized in that caused by a voltage applied between the counter electrode in contact with an electrolyte solution with the source electrode or the drain electrode or 6 The manufacturing method of the organic-semiconductor device of description.
The fourth step is a step of causing the reduction reaction,
The above reduction reaction is, according to claim 2 or 7, characterized in that caused by a voltage applied between the the source electrode or the drain electrode, a counter electrode in contact with an electrolyte solution with the source electrode or said drain electrode The manufacturing method of the organic-semiconductor device of description.
A method of manufacturing an organic semiconductor device having a p-type organic transistor and an n-type organic transistor,
A first step of forming a gate insulating layer on the gate electrode;
a second step of forming a source electrode and a drain electrode constituting the p-type organic transistor and a source electrode and a drain electrode constituting the n-type organic transistor on the gate insulating layer;
A third step of forming a material layer made of a material or molecule having an electric dipole moment on the source electrode and the drain electrode;
The material layer above the source electrode of the p-type organic transistor and the material layer above the drain electrode of the n-type organic transistor, or the material layer above the drain electrode of the p-type organic transistor and the source of the n-type organic transistor The material of the material layer on the electrode or the direction of the electric dipole moment from the negative electrode to the positive electrode of the molecule is reversed, and the p-type injection improving layer and the n-type organic transistor are formed on the source electrode of the p-type organic transistor. A fourth type in which an n-type extraction improving layer is provided on the drain electrode, and a p-type extraction improving layer is provided on the drain electrode of the p-type organic transistor and an n-type injection improving layer is provided on the source electrode of the n-type organic transistor. Process,
and a fifth step of forming an organic semiconductor layer in contact with the injection improving layer and the extraction improving layer of the p-type organic transistor and an organic semiconductor layer in contact with the injection improving layer and the extraction improving layer of the n-type organic transistor. A method of manufacturing an organic semiconductor device characterized by the above.
The material layer above the source electrode of the p-type organic transistor and the material layer above the drain electrode of the n-type organic transistor, or the material layer above the drain electrode of the p-type organic transistor and the source of the n-type organic transistor The above material layer on the electrode is combined with any one of oxidation reaction, reduction reaction, photochemical reaction, photooxidation reaction, and photoreduction reaction, or a plurality of these reactions. 14. The method of manufacturing an organic semiconductor device according to claim 13, wherein a reaction is caused to reverse the direction of the electric dipole moment of the material layer.
The method of manufacturing an organic semiconductor device according to any one of claims 1 to 14, wherein, in the second step, the source electrode and the drain electrode are formed using the same material.