JP2004311979A - Organic thin film transistor and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic thin film transistor of high performance and high reliability in which off-state current is restrained even when an organic thin film if used. <P>SOLUTION: The organic thin film transistor comprises a substrate, the organic thin film comprising a monomolecular film or a built-up film of a silicon compound represented by a formula R-SiX<SP>1</SP>X<SP>2</SP>X<SP>3</SP>(I) (in the formula, R is an organic residue constituted by combining π electronic conjugated units which may be substituted for a functional group at a terminal, X<SP>1</SP>, X<SP>2</SP>and X<SP>3</SP>are the same or different from one another, and a group which gives a hydroxy group by hydrolysis.), a gate electrode formed on one surface of the organic thin film with a gate insulation film between, and source/drain electrodes which are on both sides of the gate electrode, and formed in contact with one surface or the other surface of the organic thin film. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an organic thin film transistor and a method for manufacturing the same. More specifically, the present invention relates to an organic thin film transistor using a specific silicon compound for a semiconductor layer and a method for manufacturing the same.

  In recent years, for organic semiconductors using inorganic materials, synthesis of organic compounds with more diverse functions than inorganic materials has been anticipated, because manufacturing is easy and easy to process, it can respond to device enlargement, and cost reduction is expected due to mass production. For this reason, research and development of semiconductors using organic compounds (organic semiconductors) have been conducted, and the results have been reported.

Among them, it is known that a TFT having a large mobility can be manufactured by using an organic compound containing a π-electron conjugated molecule. Pentacene has been reported as a typical example of this organic compound (for example, IEEE Electron Device Lett., 18, 606-608 (1997)). Here, when an organic semiconductor layer is formed using pentacene and a TFT is formed using the organic semiconductor layer, a field-effect mobility becomes 1.5 cm ² / Vs, and a TFT having mobility higher than that of amorphous silicon is constructed. It has been reported that it is possible.

  However, when an organic compound semiconductor layer for obtaining a higher field-effect mobility than amorphous silicon as described above is manufactured, a vacuum process such as a resistance heating evaporation method or a molecular beam evaporation method is required. Is complicated, and a film having crystallinity can be obtained only under certain specific conditions. Further, since the adsorption of the organic compound film on the substrate is physical adsorption, there is a problem that the film has a low adsorption strength on the substrate and is easily peeled off. Further, in order to control the orientation of the molecules of the organic compound in the film to some extent, the orientation of the substrate on which the film is to be formed is usually controlled by rubbing or the like. It has not yet been reported that the conformity and orientation of the molecules of the compound at the interface between the organic compound and the substrate can be controlled.

  On the other hand, regarding the regularity and crystallinity of a film, which greatly influence the field-effect mobility, which is a typical guideline of the characteristics of the TFT, the self-assembly using an organic compound has recently been carried out because of its simple production. Attention has been paid to membranes, and research utilizing the membranes has been made.

  A self-assembled film is a film in which a part of an organic compound is bonded to a functional group on the surface of a substrate, and has very few defects and high order, that is, a film having high crystallinity. Since the self-assembled film has a very simple manufacturing method, it can be easily formed on a substrate. Usually, a thiol film formed on a gold substrate or a silicon-based compound film formed on a substrate (for example, a silicon substrate) capable of projecting a hydroxyl group on the surface by a hydrophilization treatment is known as a self-assembled film. I have. Above all, silicon-based compound films have attracted attention because of their high durability. The silicon-based compound film has been conventionally used as a water-repellent coating, and has been formed using a silane coupling agent having an alkyl group having a high water-repellent effect or an alkyl fluoride group as an organic functional group.

  However, the conductivity of the self-assembled film is determined by the organic functional groups in the silicon-based compound contained in the film. Commercially available silane coupling agents include π-electron conjugated molecules in the organic functional groups. Since there is no compound, it is difficult to impart conductivity to the self-assembled film. Therefore, there is a need for a silicon-based compound that is suitable for a device such as a TFT and contains a π-electron conjugated molecule as an organic functional group.

  As such a silicon-based compound, a compound having one thiophene ring as a functional group at the terminal of a molecule and in which the thiophene ring is bonded to a silicon atom via a linear hydrocarbon group has been proposed (for example, Patent No. No. 2889768: Patent Document 1). Furthermore, as a polyacetylene film, a film in which a -Si-O- network is formed on a substrate by a chemical adsorption method to polymerize an acetylene group portion has been proposed (for example, Japanese Patent Publication No. Hei 6-27140: Patent). Reference 2). Further, as the organic material, a silicon compound in which a linear hydrocarbon group is bonded to each of the 2- and 5-positions of the thiophene ring, and a terminal of the linear hydrocarbon is bonded to a silanol group, is used for self-organization on a substrate. An organic device has been proposed in which a conductive thin film is formed by polymerizing molecules by electric field polymerization or the like, and using the conductive thin film as a semiconductor layer (for example, Japanese Patent No. 2507153: Patent Document 3). ). Furthermore, a field effect transistor using a semiconductor thin film containing a silicon compound having a silanol group in a thiophene ring contained in polythiophene as a main component has been proposed (for example, Japanese Patent No. 2725587: Patent Document 4).

Japanese Patent No. 2889768 Japanese Patent Publication No. 6-27140 Japanese Patent No. 2507153 Japanese Patent No. 2725587

  However, although the compounds proposed above can produce a self-assembled film capable of being chemically adsorbed to a substrate, a film having high ordering, crystallinity, and electric conduction properties that can be used for an electronic device such as a TFT. Could not always be produced. Furthermore, when the compound proposed above is used for the semiconductor layer of the organic TFT, there is a problem that the off-state current becomes large. This is probably because the proposed compounds all have bonds in the direction of the molecule and in the direction perpendicular to the molecule.

  In order to obtain high order, that is, high crystallinity, a high attractive interaction must be exerted between molecules. The intermolecular force is composed of an attractive term and a repulsive term. The former is inversely proportional to the sixth power of the intermolecular distance, and the latter is inversely proportional to the twelfth power of the intermolecular distance. Therefore, the intermolecular force obtained by adding the attraction term and the repulsion term has a relationship shown in FIG. Here, the minimum point (arrow portion in the figure) in FIG. 11 is the intermolecular distance when the highest attractive force acts between the molecules due to the balance between the attractive term and the repulsive term. That is, in order to obtain higher crystallinity, it is important to make the intermolecular distance as close as possible to the minimum point. Therefore, originally, in vacuum processes such as resistance heating evaporation and molecular beam evaporation, only under certain conditions, by properly controlling the intermolecular interaction between π-electron conjugated molecules, high ordering, That is, crystallinity is obtained. As described above, it is possible to exhibit high electric conductivity only by the crystalline structure formed by the intermolecular interaction.

  On the other hand, the above compound may chemically adsorb to the substrate by forming a two-dimensional network of Si—O—Si, and may obtain the order by the intermolecular interaction between specific long-chain alkyls. However, since only one thiophene molecule as a functional group contributes to the π-electron conjugated system, the interaction between the molecules is weak, and the spread of the π-electron conjugated system, which is indispensable for electric conductivity, is very small. there were. Even if the number of thiophene molecules, which are the functional groups, can be increased, the factors that form the order of the film match the intermolecular interactions between the long-chain alkyl moiety and the thiophene moiety. It is difficult to do so.

  Further, with respect to the electric conduction characteristics, one thiophene molecule which is a functional group has a problem that a HOMO-LUMO energy gap is large, and sufficient carrier mobility cannot be obtained even when used for a TFT or the like as an organic semiconductor layer. Existed.

  The present invention has been made in view of the above problems, and can be easily crystallized by a simple manufacturing method to form a film, and strongly adheres the obtained film to a substrate surface to provide a physical solution. It is an object of the present invention to provide a TFT provided with a film having high ordering, crystallinity, and electric conduction characteristics while preventing peeling off.

  It is still another object of the present invention to provide a TFT using an organic thin film, which secures sufficient carrier mobility and suppresses off-current, and has high performance and high reliability.

  In order to achieve the above object, as a result of intensive studies, in order to produce an organic thin film applicable to an electronic device such as a TFT, a two-dimensional network of Si—O—Si is formed to form a strong chemical bond with a substrate. At the same time, the order (crystallinity) of the organic thin film is controlled by the interaction of molecules (here, π-electron conjugated molecules) formed on the two-dimensional network of Si—O—Si, that is, the intermolecular force. The inventors have found that this is possible and have led to the present invention.

Thus, according to the present invention, a substrate,
Formula R-SiX ¹ X ² X ³ (I)
(Wherein, R is an organic residue having a π-electron conjugated unit which may be substituted with a functional group at the terminal, and X ¹ , X ² and X ³ are the same or different; It is a group that gives a hydroxyl group by hydrolysis.)
An organic thin film consisting of a monomolecular film or a cumulative film of a silicon compound represented by
A gate electrode formed on one surface of the organic thin film via a gate insulating film,
There is provided an organic thin film transistor including source / drain electrodes formed on both sides of the gate electrode and in contact with one surface or the other surface of the organic thin film.

Furthermore, according to the present invention, a substrate, an organic thin film,
A gate electrode formed on one surface of the organic thin film via a gate insulating film,
On both sides of the gate electrode, a source / drain electrode formed in contact with one surface or the other surface of the organic thin film, and the organic thin film comprises:
Formula R-SiX ¹ X ² X ³ (I)
(Wherein, R is an organic residue having a π-electron conjugated unit which may be substituted with a functional group at the terminal, and X ¹ , X ² and X ³ are the same or different; It is a group that gives a hydroxyl group by hydrolysis.)
A first monomolecular film formed using a silicon compound represented by
On the first monomolecular film, an organic thin film transistor including a silicon compound containing a π-electron conjugated unit composed of a plurality of groups formed by at least one film is provided. .

Further, according to the present invention, a substrate, an organic thin film,
A gate electrode formed on one surface of the organic thin film via a gate insulating film,
A method of manufacturing an organic thin film transistor comprising: a source / drain electrode formed on both sides of the gate electrode and in contact with one surface or another surface of the organic thin film,
Organic thin film
Formula R-SiX ¹ X ² X ³ (I)
(Wherein, R is an organic residue having a π-electron conjugated unit which may be substituted with a functional group at the terminal, and X ¹ , X ² and X ³ are the same or different; It is a group that gives a hydroxyl group by hydrolysis.)
And a method for manufacturing an organic thin film transistor formed as a monomolecular film or a cumulative film using the silicon compound represented by the formula:

Furthermore, according to the present invention, a substrate, an organic thin film,
A gate electrode formed on one surface of the organic thin film via a gate insulating film,
A method of manufacturing an organic thin film transistor comprising: a source / drain electrode formed on both sides of the gate electrode and in contact with one surface or another surface of the organic thin film,
On the substrate,
Formula R-SiX ¹ X ² X ³ (I)
(Wherein, R is an organic residue having a π-electron conjugated unit which may be substituted with a functional group at the terminal, and X ¹ , X ² and X ³ are the same or different; It is a group that gives a hydroxyl group by hydrolysis.)
A first monomolecular film was formed by a chemisorption method using a silicon compound represented by, and a π-electron conjugated unit was contained on the first monomolecular film by using a chemisorption method. There is provided a method for manufacturing an organic thin film transistor including a step of forming at least one or more second monomolecular films made of a silicon compound.

  According to the present invention, the compound of the formula (I) is chemically adsorbed to the substrate by the two-dimensional networking of Si—O—Si formed between silicon compounds having π-electron conjugated molecules, and the crystal of the film is formed. Since the intermolecular interaction between π-electron conjugated molecules, which is the short-range force required for the formation of the molecules, works efficiently, a highly crystallized film with extremely high stability can be obtained. Can be configured. Therefore, as compared with a film formed by physical adsorption on a substrate, the obtained film can be firmly adsorbed on the substrate surface and physical peeling can be prevented.

  In addition, a network derived from a silicon compound constituting an organic thin film is directly bonded to an organic residue constituting an upper portion, and a high ordering property (crystals) is formed by an intermolecular interaction between the network derived from the silicon compound and a π-conjugated molecule. ) Can be formed. Thereby, carriers move smoothly by hopping conduction in a direction perpendicular to the molecular plane. Further, since high conductivity is obtained also in the molecular axis direction, it becomes possible to use the organic thin film transistor as a conductive material.

  Further, as the organic thin film, it is possible to use a monomolecular film which is extremely thin, about several tens of mm, has high conductivity in a direction perpendicular to the unit bonding direction, and has high semiconductivity in the unit bonding direction. Therefore, by applying a voltage between the source electrode-drain electrode and the gate electrode-drain electrode and changing the voltage between the gate electrode and the drain electrode, the amount of charge injection of holes or electrons into the monomolecular film is controlled. Thus, a high-performance organic thin film transistor can be provided.

  In other words, by utilizing carrier hopping conduction between π-electron conjugated units included in molecules constituting the organic thin film, when no voltage is applied between the gate electrode and the drain electrode, the source electrode-drain The current flowing between the electrodes can be further reduced, and the off-state current can be reduced. In addition, when a voltage between the gate electrode and the drain electrode is applied, the current flowing between the source electrode and the drain electrode can be increased.

  In particular, by using an organic molecule having a silanol group at a terminal, a self-assembled monomolecular film can be chemically adsorbed on a hydrophilic substrate surface in an organic solvent. Therefore, a thin film having a highly ordered structure can be formed. Therefore, miniaturization of the transistor can be achieved.

  In addition, since the organic thin film can use a self-assembled monolayer, it is not necessary to perform an orientation treatment as a pretreatment when constructing the organic thin film, and the organic thin film can be easily manufactured. That is, a constant amount of pure water is slowly put on a substrate whose surface has been hydrophilized, and a certain amount of an organic solvent containing a silicon compound containing a π-electron conjugated unit is dropped on the pure water. An organic thin film can be manufactured by a simple method of forming a two-dimensional network of Si—O—Si on the interface between the substrate and the organic solvent and evaporating pure water to adsorb the silicon compound on the substrate. As a result, a high-performance transistor can be easily manufactured.

  The organic thin film transistor of the present invention mainly includes a substrate, an organic thin film, a gate insulating film, a gate electrode, and source / drain electrodes. The transistor can take various forms such as a staggered type, an inverted staggered type, or a modification thereof. For example, in the case of a staggered type, an organic thin film is formed on a substrate, and a gate electrode is disposed on the organic thin film via a gate insulating film.On both sides of the gate electrode, the organic thin film is separated. And a mode in which source / drain electrodes in contact with the electrodes are arranged. Also, a gate electrode is formed on the substrate, an organic thin film is formed on the gate electrode via a gate insulating film, and the source / drain electrode is in contact with the organic thin film on the organic thin film without overlapping with the gate electrode. May be arranged.

  The substrate can be appropriately selected depending on the type of the organic thin film, the configuration and the performance of the transistor, and the like. For example, semiconductors such as elemental semiconductors such as silicon and germanium, compound semiconductors such as GaAs, InGaAs, and ZnSe; glass, quartz glass; insulating polymer films such as polyimide, PET, PEN, PES, and Teflon (registered trademark); Substrates made of stainless steel (SUS); metals such as gold, platinum, silver, copper, and aluminum; high-melting metals such as titanium, tantalum, and tungsten; and substrates made of materials such as silicide and polycide with high-melting metals. Further, a so-called SOI substrate, multilayer SOI substrate, SOS substrate, or the like can be used. These substrates may be used alone or a plurality of them may be laminated. In particular, when an organic thin film is formed directly on a substrate, a substrate capable of protruding active hydrogen such as a hydroxyl group or a carboxyl group from the surface by a hydrophilic treatment is preferable. The hydrophilization treatment can be performed, for example, by immersion in a mixed solution of hydrogen peroxide and concentrated sulfuric acid.

  The organic thin film is a film obtained by forming a monomolecular film or a cumulative film obtained by stacking them, using a silicon compound containing an organic residue formed by combining a plurality of π-electron conjugated units. In particular, the silicon compound may be directly bonded to the substrate, the gate insulating film, or the like, but is preferably bonded by a siloxane bond (—Si—O—). In addition, it is preferable that adjacent units in the substrate surface direction are not bonded to each other, and that a plurality of units in the silicon compound are linearly bonded.

Specifically, the organic thin film
Formula R-SiX ¹ X ² X ³ (I)
(Wherein, R is an organic residue having a π-electron conjugated unit which may be substituted with a functional group at the terminal, and X ¹ , X ² and X ³ are the same or different; It is a group that gives a hydroxyl group by hydrolysis.)
Can be formed using a silicon compound represented by the formula:

  In the formula (I), R is an organic residue formed by bonding a plurality of π-electron conjugated units. For example, the unit includes a group derived from a compound selected from a monocyclic aromatic hydrocarbon and a monocyclic heterocyclic compound.

  Examples of the monocyclic aromatic hydrocarbon include benzene, toluene, xylene, mesitylene, cumene, cymene, styrene, divinylbenzene and the like. Of these, benzene is preferred. Hetero atoms contained in the monocyclic heterocyclic compound include oxygen, nitrogen and sulfur atoms. Specific examples of the heterocyclic compound include compounds containing an oxygen atom such as furan, compounds containing a nitrogen atom such as pyrrole, pyridine, pyrimidine, pyrroline, imidazoline and pyrazoline, compounds containing a sulfur atom such as thiophene, oxazole and isoxazole. Examples thereof include compounds containing nitrogen and oxygen atoms, compounds containing sulfur and nitrogen atoms such as thiazole and isothiazole, and among them, thiophene is particularly preferable.

  A plurality of units derived from a monocyclic aromatic hydrocarbon or a monocyclic heterocyclic compound may be bonded in a branched manner, but are preferably bonded in a linear manner. It is preferable that 3 to 10 units are bonded in consideration of the yield, and it is more preferable that 3 to 8 units of the unit are bonded in consideration of economy and mass production. Further, the organic residue may be the same unit bonded, all different unit compounds may be bonded, or plural types of units may be bonded regularly or in random order. .

  Further, a vinylene group may be located between the units. Examples of the hydrocarbon that provides a vinylene group include alkenes, alkadienes, and alkatrienes. Examples of the alkene include compounds having 2 to 4 carbon atoms, for example, ethylene, propylene, butylene and the like. Of these, ethylene is preferred. Examples of alkadienes include compounds having 4 to 6 carbon atoms, butadiene, pentadiene, hexadiene and the like. Alkatriene includes compounds having 6 to 8 carbon atoms, for example, hexatriene, heptatriene, octatriene and the like.

  When the constituent molecule of the unit is a 5-membered ring, the position of the bond may be any of the 2,5-position, 3,4-position, 2,3-position, 2,4-position and the like. Of these, the 2,5-position is preferred. In the case of a 6-membered ring, any of the 1,4-position, 1,2-position, 1,3-position and the like may be used, and among them, the 1,4-position is preferable.

  For example, specific examples of this unit include biphenyl, bithiophenyl, terphenyl, terthienyl, quarterphenyl, quarterthiophene, quinkephenyl, quinkethiophene, hexphenyl, hexthiophene, thienyl-oligophenylene (compound of formula (3) Group) derived from phenyl-oligothienylene (see the compound of formula (4)), block cooligomer (see the compound of formula (5) or (6)), ethylene group, diethylene group, etc. And a group containing one or more conjugated double bonds without a cyclic molecule such as ethylene in the unit of (1).

Functional groups which can be replaced at the end of the organic residue, for example, be represented as the substituent K ¹ represented by the formula ^{K 1 -R'-SiX 1 X 2} X 3 (I '). Examples of the substituent K ¹ include a hydroxyl group, a substituted or unsubstituted amino group, a nitro group, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted cycloalkyl group, and a substituted or unsubstituted cycloalkyl group. Or an unsubstituted alkoxy group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted Or a carboxyl group or an ester group. Among these functional groups, a functional group that does not hinder the crystallization of the organic thin film due to steric hindrance is preferable. Therefore, a linear alkyl group having 1 to 30 carbon atoms is particularly preferable among the above functional groups. When a cumulative film is formed, the functional group is preferably a functional group capable of binding to a compound to be laminated on the second and subsequent layers, and is more preferably located at a terminal of an organic residue. Examples of such a functional group include an amino group, a carboxyl group, an acyl group, a formyl group, a carbonyl group, a nitro group, a nitroso group, an azide group, an acid azide group, and an acid chloride group.

Further, the functional group may be optionally protected with a protecting group. In other words, these functional groups are not limited to those capable of directly reacting with the substituents of the compounds to be laminated on the second and subsequent layers, but may be obtained by several steps of processes (for example, including deprotection). It may be a compound which can be converted into a substituent capable of reacting with a compound to be laminated on and after the layer. Examples of the substituent conversion process include a catalytic reaction and a light conversion reaction (eg, reduction of a nitro group to an amino group in the presence of a nickel catalyst).
In the formula (I ′), R ′ has the same meaning as R except that the terminal is not substituted with a functional group.

  In addition, when the substrate surface has hydrophilicity, by inserting a lipophilic or hydrophobic substituent into the terminal of the organic residue of the silicon compound, the adsorptivity to the substrate (the hydrophilic group of the substrate and the hydrophilic Are easily bonded), leading to an improvement in reaction efficiency. That is, there is an effect that the reactivity with the substrate is improved by increasing the lipophilicity or the hydrophobicity of the portion other than the silanol group, which is the reaction site between the silicon compound and the hydrophilic substrate. Further, when the compound has a lipophilic or hydrophobic substituent, the solubility in a non-aqueous solution that is a reaction solution with the substrate can be improved.

  As described above, by forming a structure having an appropriate substituent according to the purpose at the terminal of the silicon compound, the reactivity and solubility of the monomolecular film formed on the substrate, and further binding of other materials can be achieved. Thus, the stability of the formed film can be increased.

  As described above, a desired function can be imparted to the organic thin film by employing a structure having a functional group at the terminal of the compound. In the above description, the functional group formed at the terminal of the silicon compound in the first layer has been described, but the same can be said for the terminal when a cumulative film is formed.

The group that gives a hydroxyl group by hydrolysis in X ¹ , X ² and X ³ is not particularly limited, and examples thereof include a halogen atom and a lower alkoxy group. Examples of the halogen atom include fluorine, chlorine, iodine, and bromine atoms.

Examples of the lower alkoxy group include an alkoxy group having 1 to 4 carbon atoms. For example, a methoxy group, an ethoxy group, an n-propoxy group, a 2-propoxy group, an n-butoxy group, a sec-butoxy group, a tert-butoxy group and the like can be mentioned, and some of them are further functional groups (trialkylsilyl). Group or another alkoxy group). X ¹ , X ² and X ³ may be the same, but not necessarily all.

  Specific examples of the silicon compound of the formula (I) include the following.

(In the formula, n is 2 to 8, m is 2 to 5, and a + b is 3 to 10.)

Hereinafter, a method for synthesizing the silicon compound will be described.
The silicon compound represented by the formula (I) is
A compound represented by the formula R-Li (II) and a formula Y-SiX ¹ X ² X ³ (III) (wherein X ¹ , X ² , X ³ and Y are as defined above). Reacting with the represented compound, or
-It can be obtained by subjecting a compound represented by the formula R-MgX (IV) (wherein R and X are as defined above) to a Grignard reaction with a compound represented by the above formula (III). it can.

  The compound of the formula (II) or (IV) can be obtained, for example, by reacting a compound represented by RH with alkyllithium, alkylmagnesium halide, metal magnesium, or the like.

  Examples of the alkyl lithium used in this reaction include lower (about 1 to 4 carbon atoms) alkyl lithiums such as n-butyl lithium, s-butyl lithium, and t-butyl lithium. The use amount thereof is preferably 1 to 5 mol, more preferably 1 to 2 mol, per 1 mol of the compound RH. Examples of the alkyl magnesium halide include ethyl magnesium bromide and methyl magnesium chloride. The amount used is preferably from 1 to 10 mol, more preferably from 1 to 4 mol, per 1 mol of the starting compound R-XH.

  The reaction temperature is, for example, preferably from -100 to 150 ° C, more preferably from -20 to 100 ° C. The reaction time is, for example, about 0.1 to 48 hours. The reaction is usually performed in an organic solvent that does not affect the reaction. Examples of the organic solvent that does not adversely affect the reaction include aliphatic or aromatic hydrocarbons such as hexane, pentane, benzene, and toluene, and ether solvents such as diethyl ether, dipropyl ether, dioxane, and tetrahydrofuran (THF). These can be used alone or as a mixture. Of these, diethyl ether and THF are preferred. The reaction may optionally use a catalyst. As the catalyst, a known catalyst such as a platinum catalyst, a palladium catalyst, and a nickel catalyst can be used.

  The method for synthesizing the silicon compound represented by the formula (I) will be described more specifically below. The reaction temperature and reaction time in the following synthesis methods are the same as those described above, and are, for example, -100 to 150 ° C and 0.1 to 48 hours.

  In the following, a synthesis example of a precursor of an organic residue composed of a unit derived from benzene which is an example of a monocyclic aromatic hydrocarbon and a unit derived from thiophene which is an example of a monocyclic heterocyclic compound will be described. Show. However, a precursor can also be formed for a heterocyclic compound containing a nitrogen atom and an oxygen atom in the same manner as for a nitrogen-containing heterocyclic compound such as thiophene.

  As a method for synthesizing a precursor composed of a unit derived from benzene or thiophene, a method in which a reaction site of benzene or thiophene is first halogenated, and then a Grignard reaction is used is effective. By using this method, a precursor in which the number of benzene or thiophene is controlled can be synthesized. In addition to the method using a Grignard reagent, it can also be synthesized by coupling using a suitable metal catalyst (Cu, Al, Zn, Zr, Sn, etc.).

  Further, for thiophene, the following synthesis method can be used in addition to the method using a Grignard reagent.

That is, first, the 2′-position or 5′-position of thiophene is halogenated (for example, chlorinated). Examples of the method of halogenation include a treatment of one equivalent of N-chlorosuccinimide (NCS) and a treatment with phosphorous oxychloride (POCl ₃ ). As a solvent at this time, for example, a mixed solution of chloroform / acetic acid (AcOH) or DMF can be used. Further, the halogenated thiophenes are reacted with each other in a DMF solvent using tris (triphenylphosphine) nickel (tris (phenylphenylphosphine) Nickel: (PPh ₃ ) 3Ni) as a catalyst, thereby resulting in a halogenated portion. Thiophenes can be directly bonded to each other.

Further, divinyl sulfone is added to the halogenated thiophene and coupled to form a 1,4-diketone. Subsequently, a ring closure reaction is caused by adding a Low Wesson agent (LR) or P ₄ S ₁₀ in a dry toluene solution and refluxing the former overnight or about 3 hours in the latter. As a result, a precursor in which the number of thiophenes is one more than the total number of coupled thiophenes can be synthesized.
Using the above reaction of thiophene, the number of thiophene rings can be increased.

The terminal of the precursor can be halogenated in the same manner as the raw material used for the synthesis. For this reason, after the precursor is halogenated, it is reacted with, for example, SiCl ₄ to obtain a silicon compound having a silyl group at a terminal and having an organic residue consisting of only a unit derived from benzene or thiophene (simple benzene). Or a simple thiophene compound) can be obtained.

  As an example, the following (A) to (D) show an example of a method for synthesizing a precursor of an organic residue consisting only of benzene or thiophene and a method for silylating the precursor. In the following synthesis example of a precursor composed of only thiophene, only a reaction from a thiophene trimer to a hexamer or a heptamer was shown. However, by reacting with a thiophene having a different number of units, a precursor other than the hexamer or heptamer can be formed. For example, thiophene tetramer or pentamer can be formed by reacting 2-chlorobithiophene chlorinated with NCS after coupling 2-chlorothiophene in the same manner as described below. Further, if the thiophene tetramer is chlorinated by NCS, a thiophene 8 or 9-mer can be further formed.

As a method of obtaining a precursor of a block-type organic residue by directly bonding a unit in which a predetermined number of thiophenes and units derived from benzene are bonded, for example, there is a method using a Grignard reaction. The target silicon compound can be obtained by reacting the precursor with SiCl ₄ or HSi (OEt) ₃ . In addition, among the above compounds, compounds having a silyl group at the terminal alkoxy group have relatively low reactivity, and thus can be synthesized in a state in which they are bonded to raw materials in advance. The following method can be applied as a synthesis example in this case.

First, after a silyl group and a reverse end of a simple benzene or simple thiophene compound are halogenated (for example, brominated), a functional group bonded to the silyl group is converted from a halogen to an alkoxy group by a Grignard reaction. Subsequently, debromination and boration can be performed by adding n-BuLi and B (O-iPr) ₃ . The solvent at this time is preferably an ether. The reaction in the case of boration is a two-stage reaction. In the initial stage, in order to stabilize the reaction, the first stage is performed at -78 ° C, and the second stage is performed by gradually raising the temperature from -78 ° C to room temperature. Preferably. On the other hand, an intermediate of a block compound is prepared from a Grignard reaction using benzene or thiophene having a halogen group (for example, a bromo group) at both ends.

In this state, the unreacted bromo group and the borated compound are developed in, for example, a toluene solvent, and at a reaction temperature of 85 ° C. in the presence of Pd (PPh ₃ ) ₄ and Na ₂ CO ₃ , If the reaction is allowed to proceed completely, coupling can occur. As a result, a silicon compound having a silyl group at the terminal of the block type compound can be synthesized.

An example of a synthesis route for the silicon compounds (E) and (F) using such a reaction is shown below. Compounds having a halogen group (for example, a bromo group) and a trichlorosilyl group at both ends of a unit derived from benzene or thiophene are p-phenylene or 2,5-thiophenediyl and a halogenating agent (for example, NBS) After halogenating both terminals by the reaction with, a reaction with SiCl ₄ and trichlorosilylation of one of them are possible.

As a method of synthesizing a precursor in which a unit derived from benzene or thiophene and a vinyl group are alternately bonded, for example, the following method can be applied. That is, after preparing a raw material having a methyl group at the reaction site of benzene or thiophene, both ends thereof are made of 2,2'-azobisisobutyronitrile (AIBN) and N-bromosuccinimide (NBS). And brominated. Thereafter, the bromo compound is reacted with PO (OEt) ₃ to form an intermediate. Subsequently, the precursor having the aldehyde group at the terminal is reacted with the intermediate using, for example, NaH in a DMF solvent, whereby the precursor can be formed. Since the obtained precursor has a methyl group at the terminal, for example, if the methyl group is further brominated and the above synthesis route is applied again, a precursor having a larger number of units can be formed.

If the obtained precursor is brominated using, for example, NBS, it is possible to react the portion with SiCl ₄ . Therefore, a silicon compound having SiCl ₃ at the terminal can be formed. An example of a synthesis route for precursors (G) to (I) having different lengths and a silicon compound (J) using such a reaction is shown below.

  For any compound, a raw material having a side chain (for example, an alkyl group) at a predetermined position can also be used. That is, for example, when 2-octadecyl terthiophene is used as a raw material, 2-octadecyl sexithiophene can be obtained as the precursor (A) by the above synthesis route. Therefore, 2-octadecylsexithiophene trichlorosilane can be obtained as the silicon compound (C). Similarly, if a raw material having a side chain in advance at a predetermined position is used, any of the compounds (A) to (J) and a compound having a side chain can be obtained.

  The raw materials used in the above synthesis examples are general-purpose reagents, which can be obtained and used from reagent manufacturers. The CAS number of the raw material and the purity of the reagent when obtained from, for example, Kishida Chemical as a reagent maker are shown below.

  The silicon compound represented by the formula (I) thus obtained can be isolated from the reaction solution by a known means, for example, phase transfer, concentration, solvent extraction, fractionation, crystallization, recrystallization, chromatography, or the like. It can be purified.

  The silicon compound of the formula (I) can be formed into a thin film as follows, for example, by a chemisorption method.

First, the silicon compound of the formula (I) is dissolved in a non-aqueous organic solvent such as hexane, chloroform, carbon tetrachloride, and n-hexadecane. In the formula (I), when the substituents X ¹ , X ² and / or X ³ are an alkoxy group, for example, a non-aqueous solution is used for promoting a reaction such as hydrolysis. You may.

  The concentration of the solution at this time is not particularly limited, but for example, about 1 mM to 100 mM is appropriate. A substrate on which a thin film is to be formed (preferably, a substrate having active hydrogen such as a hydroxyl group or a carboxyl group) is immersed in the obtained solution and pulled up. Alternatively, the obtained solution may be applied to the substrate surface. Thereafter, the thin film can be washed with a non-aqueous organic solvent and dried by being left or heated to fix the thin film. This thin film may be used as it is as a functional organic thin film, or may be used after further processing such as electrolytic polymerization.

  The thin film formed as described above may be a monomolecular film, or may be a cumulative film obtained by stacking them.

The accumulation film can be formed as follows.
First, as shown in FIG. 4A, a monomolecular film of a silicon compound having a functional group (for example, an amino group or the like) at a terminal is formed on the substrate 31 by, for example, a chemical adsorption method. For example, the obtained substrate 31 is immersed in a solution containing a compound (for example, a compound of the formula (8)) having a functional group (for example, a carboxyl group or the like) capable of reacting with a terminal functional group, By reacting, as shown in FIG. 4B, a cumulative film having no bond with an adjacent molecule can be formed without changing the structure of the first monolayer.

Note that the method of manufacturing the cumulative film is not limited to the above, and any method may be used as long as it is a general method that can be stacked. As a general method, in addition to the above-mentioned method, the terminal is changed to a functional group capable of reacting with the compound to be laminated by electrolytic polymerization treatment, catalytic reaction, or the like on the first monolayer formed in advance. And then reacting with the compound to be laminated. Further, the monomolecular film to be laminated on the second and subsequent layers has, for example, the formula K ² -R'-K ³ (V)
Can be formed using the compound represented by In the formula, as the functional groups for K ² and K ³ , those similar to the above K ¹ can be mentioned.

Specifically, the formula R-SiX ⁴ X ⁵ X ⁶ (VI)
(In the formula, R is as defined above, one of X ^{4 to} X ^{6 is} a group that provides a hydroxyl group by hydrolysis, and the other two are functional groups that do not react with adjacent molecules.)
Can be formed using a compound represented by the formula: In the formula, the group which gives a hydroxyl group by hydrolysis of X ^{4 to} X ⁶ is the same as the group represented by X ^{1 to} X ³ . In addition, examples of the functional group that does not react with an adjacent molecule include an alkyl group.

  Examples of such a compound include, but are not limited to, the compound of the above formula (8), and include a π-electron conjugated unit and a first monolayer film. Any compound having a functional group capable of reacting with a compound may be used.

  The thickness of the monomolecular film can be appropriately adjusted depending on the number of organic residues bonded. For example, the thickness is preferably about 1 nm to 12 nm, and more preferably about 1 nm to 3.5 nm in consideration of economy and mass production. preferable. When the monomolecular film is a cumulative film, the film thickness is substantially c × d when the monomolecular film thickness is c and the cumulative number is d layers. When a film having a different function is produced for each monomolecular film, the molecular structure and the film thickness of the monomolecular film may be different depending on the function. Can be adjusted as appropriate.

  As described above, by forming a thin film, for example, a monomolecular film or a cumulative film, the silicon compound of the formula (I) can be easily self-organized, and a thin film in which units are oriented in a certain direction can be obtained. . In other words, a highly crystallized material can be obtained by minimizing the distance between adjacent units, and as a result, a functional organic thin film exhibiting conductivity in a direction perpendicular to the substrate surface can be obtained. .

  In the case where adjacent silicon in the formula (I) is cross-linked as it is or via an oxygen atom, for example, the distance between adjacent units is controlled to be small and more highly controlled by a Si—O—Si network. Crystallized. In particular, when the units are arranged in a straight chain, as shown in FIG. 1, the adjacent units are not bonded to each other, the distance between the adjacent units is minimized, and the crystals are highly crystallized. An organic thin film can be obtained. By such unit orientation, a functional organic thin film exhibiting semiconductor characteristics in the surface direction of the substrate can be obtained.

In particular, it is possible to obtain a thin film having electrical anisotropy having different electrical characteristics in a direction perpendicular to the surface of the substrate and in a surface direction.
Further, when the organic thin film is a cumulative film, as shown in FIG. 2, by accumulating films having different functions, it becomes possible to separate different functions into respective portions of the film in the same film. .

  An example of the gate insulating film is an insulating film used for a transistor. For example, insulating films such as a silicon oxide film (thermal oxide film, low-temperature oxide film: LTO film, high-temperature oxide film: HTO film), silicon nitride film, SOG film, PSG film, BSG film, BPSG film; PZT, PLZT, Ferroelectric or anti-ferroelectric film; SiOF-based film, SiOC-based film, CF-based film, HSQ (hydrogen silsesquioxane) -based film (inorganic), MSQ (methyl silsesquioxane) -based film, PAE (polyethylene ether) film formed by coating ) -Based films, BCB-based films, porous films, CF-based films, and low-dielectric films such as porous films. The film thickness is not particularly limited, and can be appropriately adjusted to a film thickness usually used for a transistor.

  The gate electrode and the source / drain electrodes can be generally formed using a conductive material used for a transistor or the like. Examples of the conductive material include metals such as gold, platinum, silver, copper, and aluminum; high-melting metals such as titanium, tantalum, and tungsten; silicides and polycides with high-melting metals; No. The film thickness is not particularly limited, and can be appropriately adjusted to a film thickness usually used for a transistor.

  The organic thin film transistor of the present invention can be used in various applications, for example, as a semiconductor device such as a memory, a logic element or a logic circuit, such as a personal computer, a notebook, a laptop, a personal assistant / transmitter, a minicomputer, a workstation, a mainframe, A data processing system such as a multiprocessor computer or any other type of computer system; electronic components constituting a data processing system such as a CPU, a memory, a data storage device; communication equipment such as a telephone, a PHS, a modem, a router; Image display equipment such as panels and projectors; office equipment such as printers, scanners, and copiers; sensors; imaging equipment such as video cameras and digital cameras; entertainment equipment such as game machines and music players; portable information terminals, clocks, and electronic dictionaries Information devices such as On-board equipment such as navigation systems and car audio; AV equipment for recording and reproducing information such as moving images, still images, and music; electrification of washing machines, microwave ovens, refrigerators, rice cookers, dishwashers, vacuum cleaners, air conditioners, etc. Products: Health management devices such as massagers, weight scales, and sphygmomanometers; Widely applicable to electronic devices such as portable storage devices such as IC cards and memory cards.

Hereinafter, embodiments of the organic thin film transistor and the method of manufacturing the same according to the present invention will be specifically described with reference to the drawings.
(Synthesis example)
Synthesis of terthiophene trichlorosilane In a 500 ml glass flask equipped with a stirrer, a reflux condenser, a thermometer, and a dropping funnel, 1.0 mol of terthiophene was dissolved in carbon tetrachloride, and NBS and AIBN were added. After stirring for an hour, the mixture was filtered under reduced pressure to obtain bromoterthiophene. continue,
0.5 mol of metallic magnesium and 300 ml of THF (tetrahydrofuran) are charged into a 500 ml glass flask equipped with a stirrer, a reflux condenser, a thermometer, and a dropping funnel, and 0.5 mol of the bromoterthiophene is dropped at 50 to 60 ° C. The mixture was added dropwise over 2 hours from the funnel, and after completion of the addition, the mixture was matured at 65 ° C for 2 hours to prepare a Grignard reagent.

A 1-liter glass flask equipped with a stirrer, a reflux condenser, a thermometer, and a dropping funnel was charged with 1.5 mol of SiCl ₄ (tetrachlorosilane) and 300 ml of toluene, cooled with ice, and cooled with a Grignard reagent at an internal temperature of 20 ° C. or lower. The mixture was added over a period of time, and ripening was performed at 30 ° C. for 1 hour after completion of the dropwise addition (Grignard reaction).

  Next, the reaction solution was filtered under reduced pressure to remove magnesium chloride, and then toluene and unreacted tetrachlorosilane were stripped from the filtrate, and this solution was distilled to obtain the title compound in a yield of 55%. .

The compound thus obtained was subjected to infrared absorption spectrum measurement. As a result, absorption derived from SiC was observed at 1060 cm ⁻¹ , confirming that the compound had a SiC bond. When the solution containing the compound was subjected to UV-visible absorption spectrum measurement, absorption was observed at a wavelength of 360 nm. This absorption is due to the π → π * transition of the terthiophene molecule contained in the molecule, and it was confirmed that the compound contained the terthiophene molecule. Further, the compound was subjected to nuclear magnetic resonance (NMR) measurement. Since it is impossible to directly measure this compound by NMR because of the high reactivity of the compound, the compound is reacted with ethanol (the generation of hydrogen chloride was confirmed), and the terminal chlorine was exchanged for an ethoxy group. After the measurement.

7.50 ppm to 7.00 ppm (m) (from 7H thiophene ring)
2.60 ppm to 2.5 ppm (m) (from 6H ethoxy group ethyl group)
1.4 ppm to 1.3 ppm (m) (from 9H ethoxy group methyl group)
From these results, it was confirmed that this compound was terthiophene trichlorosilane represented by the formula (2).

Example 1
Production of Organic Thin Film Transistor In order to produce the organic thin film transistor shown in FIG. 3, first, chromium was deposited on a silicon substrate 10 to form a gate electrode 15.

  Next, after depositing an insulating film 16 of a silicon nitride film by a plasma CVD method, chromium and gold were deposited in this order, and a source electrode 13 and a drain electrode 14 were formed by a usual lithography technique.

  Subsequently, the obtained substrate was immersed in a mixed solution of hydrogen peroxide and concentrated sulfuric acid (mixing ratio 3: 7) for one hour, and the surface of the insulating film 16 was hydrophilized. Thereafter, the obtained substrate was immersed in a 20 mM terthiophene trichlorosilane solution in which the terthiophene trichlorosilane obtained above was dissolved in a non-aqueous solvent (for example, n-hexadecane) for 5 minutes under anaerobic conditions, and was slowly pulled up. The organic semiconductor layer 12 was formed by solvent washing.

  The obtained organic semiconductor layer 12 showed terthiophene absorption at a wavelength of 360 nm in an ultraviolet-visible absorption spectrum, and thus it was confirmed that the silicon compound was adsorbed on the surface of the substrate (insulating film). Further, from the film thickness measurement by ellipsometry, a measurement result of 1.2 nm corresponding to the molecular length was obtained. Further, a peak was confirmed at 2θ = 22.7 ° in X-ray diffraction, and it was found that a crystalline film having a plane spacing of 0.392 nm was formed. Therefore, in this crystalline film, for example, as shown in FIG. 1, it can be said that adjacent terthiophene molecules are regularly formed. That is, a π-electron conjugated unit is bonded to the surface of the insulating film 16 through a siloxane bond, but is not bonded between adjacent silicon compounds. That is, it is reasonable to presume that adjacent terthiophene molecules can form a crystalline film having a high degree of order by mutual interaction between the molecules.

  As a result, a film having high conductivity in the unit bonding direction can be obtained, and when a voltage is externally applied to the obtained organic thin film transistor, between molecules that are not bonded to adjacent molecules, between adjacent molecules. Electrons or holes are transported by so-called hopping conduction, in which electrons jump, so that the on-current can be increased. In other words, at the time of ON, since the distance between adjacent molecules is small due to the interaction between the induced dipoles, an environment in which hopping conduction easily occurs is provided, and ON current can be increased. Further, since there is no bond between adjacent organic molecules, no leakage current occurs when no external voltage is applied.

  In addition, since there is no bond between π-electron conjugated molecules (between adjacent molecules) bonded to Si included in the two-dimensional network of Si—O—Si, it is possible to reduce leakage current at the time of off.

The organic thin-film transistor obtained above had a field-effect mobility of 1 × 10 ⁻¹ cm ² / Vs and an on / off ratio of about 6 digits, and good performance was obtained.

  From the above example, using a compound having a π-electron conjugated unit and having a silanol group having a functional group capable of reacting with moisture, for example, a monomolecular film formed by a chemisorption method is Si Since a two-dimensional network of -O-Si is formed, a highly self-assembled film can be formed.

Example 2
The production of an organic transistor using a cumulative functional film as an organic thin film by laminating terthiophene trichlorosilane will be described with reference to the drawings.

First, aminoterthiophene trichlorosilane, which is the compound of the above (2 ′), was produced by the Grignard method in the same manner as in the method for producing terthiophene trichlorosilane.
A functional thin film was formed using the aminoterthiophene trichlorosilane thus prepared.

The quartz substrate subjected to the hydrophilic treatment is immersed in a 10 mM aminoterthiophene trichlorosilane solution in which aminoterthiophene trichlorosilane is dissolved in a non-aqueous solvent (for example, n-hexadecane) for 5 minutes under an inert atmosphere, The film was slowly pulled up, washed with a solvent, and a monomolecular film was formed on the quartz substrate as shown in FIG. In the obtained monomolecular film, a peak was confirmed at 2θ = 22.7 ° in X-ray diffraction, and the monomolecular film had crystallinity with a plane spacing of 0.39 nm. This monomolecular film had substantially the same crystallinity as the monomolecular film containing terthiophene. In addition, in infrared measurement of the monomolecular film, absorption derived from an amino group was confirmed at a wavelength of 3500 to 3300 cm ⁻¹ . From this, it was confirmed that the monomolecular film had an amino group.
Then, the following compound

Is prepared by immersing the monomolecular film in the solution for 1 hour, slowly pulling it up, and washing with a solvent to convert the second monomolecular film into the first monomolecular solution. A cumulative film as shown in FIG. 4C was formed on the film.

For the obtained cumulative film, a measurement result of 2.6 nm corresponding to the molecular length was obtained from the film thickness measurement by ellipsometry. In addition, in infrared measurement of the monomolecular film, absorption derived from an amide group was confirmed at a wavelength of 3200 cm ⁻¹ . As a result, it was confirmed that a cumulative film having a structure in which a silicon compound containing a group derived from terthiophene, which is a π-electron conjugated molecule, was stacked on a quartz substrate via an amide bond was formed.

  The organic thin film using the thus-prepared organic thin film as a semiconductor layer and using a cumulative film as a semiconductor layer was manufactured in the same manner as the method for manufacturing the organic thin film transistor of a terthiophene trichlorosilane monomolecular film. The obtained organic thin-film transistor had the same field-effect mobility as that of the organic thin-film transistor using terthiophene trichlorosilane, and the current value was twice or more, and good performance was obtained.

  In the example of manufacturing an organic thin film transistor using a cumulative film as a semiconductor layer, an example of lamination using an amide bond of a terthiophene trichlorosilane film was shown. However, if the first layer and the second layer are chemically bonded, Any combination is possible. Although terthiophene, one of the π-electron conjugated molecules, is described here as the compound to be stacked, any compound may be used as long as it is a π-electron conjugated molecule.

Example 3 Production of Organic Thin-Film Transistor Using 2-Octyl-Quinkethiophenetriethoxysilane In the same manner as in Example 1, the prepared substrate with an electrode was prepared by using 5 mM 2-octyl-quinquequinkethiophenetriethoxysilane toluene and An organic semiconductor layer was formed by immersing in a hydrochloric acid mixed solution for a certain period of time (for example, 10 minutes) to form a 2-octyl-quinkethiophenetriethoxysilane film, thereby forming an organic thin film transistor. FIG. 5 shows the characteristics of the formed organic thin film transistor. The organic thin film transistor formed from these results had a field effect mobility of 1.5 × 10 ⁻¹ cm ² / Vs and an on / off ratio of about 6 digits.

Example 4: Preparation of an organic thin-film transistor using 2-dodecyl-septithiophenetrichlorosilane In the same manner as in Example 1, the prepared substrate with an electrode was placed in a 2 mM 2-dodecyl-septithiophenetriethoxysilane toluene solution. For example, a 2-dodecyl-septithiophene trichlorosilane film was formed by immersing in a predetermined time (for example, 5 minutes), and an organic semiconductor layer was formed, whereby an organic thin film transistor was formed. FIG. 6 shows the characteristics of the formed organic thin film transistor. The organic thin film transistor formed from these results had a field effect mobility of 1.7 × 10 ⁻¹ cm ² / Vs and an on / off ratio of about 6 digits.

Example 5: Preparation of an organic thin film transistor using 2-hexadecyl-quarterphenyltrimethoxysilane In the same manner as in Example 1, the prepared substrate with an electrode was prepared by dissolving a 3 mM 2-hexadecylquarterphenyltrimethoxysilane in a toluene solution of 3 mM. The substrate was immersed in a predetermined time (for example, 60 minutes) to form an organic semiconductor layer by forming a 2-hexadecyl-quarterphenyltrimethoxysilane film, thereby forming an organic thin film transistor. FIG. 7 shows the characteristics of the formed organic thin film transistor. From the results, the organic thin film transistor formed had a field effect mobility of 1.3 × 10 ⁻¹ cm ² / Vs and an on / off ratio of about 6 digits.

Example 6: Preparation of an organic thin film transistor using 2-hexadecyl-octyphenyltrimethoxysilane In the same manner as in Example 1, the prepared substrate with an electrode was placed in a 3 mM 2-hexadecyl-octyphenyltrimethoxysilane toluene solution. An organic semiconductor layer was formed by forming a 2-hexadecyl-octiphenyltrimethoxysilane film by immersing for a certain period of time (for example, 60 minutes), thereby forming an organic thin film transistor. FIG. 8 shows the characteristics of the formed organic thin film transistor. The organic thin film transistor formed from these results had a field effect mobility of 1.6 × 10 ⁻¹ cm ² / Vs and an on / off ratio of about 6 digits.

Example 7 Production of Organic Thin Film Transistor Using Organosilicon Compound (Formula E) n ₁ = n ₃ = 2, n ₂ = 1 In the same manner as in Example 1, the prepared substrate with electrodes was prepared at a concentration of 1 mM (formula E). The compound thin film was formed by immersing in a THF solution of the organosilicon compound represented by E) for a certain period of time (for example, 15 minutes). Thus, an organic semiconductor layer was formed, and an organic thin film transistor was formed. FIG. 9 shows the characteristics of the formed organic thin film transistor. From the results, the organic thin film transistor formed had a field effect mobility of 1.1 × 10 ⁻¹ cm ² / Vs and an on / off ratio of about 6 digits.

Example 8 Production of Organic Thin Film Transistor Using Organosilicon Compound (Formula F) n ₄ = n ₆ = 2 and n ₅ = 3 In the same manner as in Example 1, the prepared substrate with electrodes was prepared at a concentration of 1 mM (formula F). The compound film was formed by immersing in a xylene solution of the organosilicon compound represented by F) for a certain period of time (for example, 10 minutes). Thus, an organic semiconductor layer was formed, and an organic thin film transistor was formed. FIG. 10 shows the characteristics of the formed organic thin film transistor. The organic thin film transistor formed from these results had a field-effect mobility of 2.2 × 10 ⁻¹ cm ² / Vs and an on / off ratio of about 6 digits.

It is a conceptual diagram showing the molecular arrangement of the functional organic thin film of the present invention. It is a conceptual diagram which shows the molecular arrangement | sequence of another functional organic thin film of this invention. It is a schematic sectional drawing of the organic thin-film transistor using the silicon compound of this invention. It is a conceptual diagram for demonstrating the formation method of an accumulation film. FIG. 9 is a characteristic diagram of the organic thin film transistor according to the third embodiment of the present invention. It is a characteristic view of the organic thin-film transistor in the 4th example of the present invention. It is a characteristic view of the organic thin-film transistor in the 5th Example of the present invention. It is a characteristic view of the organic thin-film transistor in the 6th Example of the present invention. It is a characteristic view of the organic thin-film transistor in the 7th Example of the present invention. It is a characteristic view of the organic thin-film transistor in the 8th Example of the present invention. FIG. 3 is a diagram for explaining a relationship between an intermolecular distance and an intermolecular force.

Explanation of reference numerals

10. Silicon substrate (substrate)
12 Organic semiconductor layer (organic thin film)
13 source electrode 14 drain electrode 15 gate electrode 16 insulating film (gate insulating film)
21 Silicon substrate (substrate)

Claims (15)

Board and
Formula R-SiX ¹ X ² X ³ (I)
(Wherein, R is an organic residue having a π-electron conjugated unit which may be substituted with a functional group at the terminal, and X ¹ , X ² and X ³ are the same or different; It is a group that gives a hydroxyl group by hydrolysis.)
An organic thin film consisting of a monomolecular film or a cumulative film of a silicon compound represented by
A gate electrode formed on one surface of the organic thin film via a gate insulating film,
An organic thin film transistor comprising: source / drain electrodes formed on both sides of the gate electrode and in contact with one surface or another surface of the organic thin film. A gate electrode is disposed on the substrate, an organic thin film is disposed on the gate electrode via a gate insulating film, and source / drain electrodes are further disposed on the organic thin film. The organic thin film transistor according to claim 1, wherein R groups are bonded via a siloxane bond, and R groups adjacent to the substrate surface in the horizontal direction are not bonded. The organic thin film transistor according to claim 1, wherein the units are linearly connected. The organic thin film transistor according to claim 1, wherein the organic thin film is formed on a substrate via a siloxane bond. The organic thin film transistor according to claim 1, wherein the unit is selected from a monocyclic aromatic hydrocarbon and a monocyclic heterocyclic compound, and the organic residue is formed by bonding 3 to 10 units. The organic thin film transistor according to claim 1, wherein the organic residue includes a vinylene group between units. The organic thin film transistor according to claim 5, wherein the monocyclic aromatic hydrocarbon and the monocyclic heterocyclic compound are benzene or thiophene groups. ^2. The organic thin film transistor according to claim ¹ , wherein X ¹ , X ² and X ³ are all the same kind of halogen atom or lower alkoxy group. The organic thin film transistor according to claim 1, wherein the organic thin film is one or a plurality of repeating films of a monomolecular film derived from the silicon compound, and the monomolecular film has a thickness of 1 nm to 12 nm. The organic thin film transistor according to claim 1, wherein the organic thin film has molecular crystallinity. The organic thin film transistor according to claim 1, wherein the organic thin film has electrical anisotropy indicating conductivity in a direction perpendicular to a substrate surface and semiconductivity in a surface direction. A substrate, an organic thin film,
A gate electrode formed on one surface of the organic thin film via a gate insulating film,
On both sides of the gate electrode, a source / drain electrode formed in contact with one surface or the other surface of the organic thin film, and the organic thin film comprises:
Formula R-SiX ¹ X ² X ³ (I)
(Wherein, R is an organic residue having a π-electron conjugated unit which may be substituted with a functional group at the terminal, and X ¹ , X ² and X ³ are the same or different; It is a group that gives a hydroxyl group by hydrolysis.)
A first monomolecular film formed using a silicon compound represented by
An organic thin film transistor comprising: a second monomolecular film containing a silicon compound containing a π-electron conjugated unit composed of a plurality of groups formed on at least one film on the first monomolecular film. The second monolayer,
Formula ^{K 2 -R'-K 3 (V} )
(Wherein, R ′ is an organic residue formed by bonding of π-electron conjugated units, and K ² and K ³ represent a functional group or a hydrogen atom. However, K ² and K ³ are hydrogen atoms at the same time. Not.)
The organic thin-film transistor according to claim 12, wherein the organic thin-film transistor is a film formed using a compound represented by the following formula: A substrate, an organic thin film,
A gate electrode formed on one surface of the organic thin film via a gate insulating film,
A method of manufacturing an organic thin film transistor comprising: a source / drain electrode formed on both sides of the gate electrode and in contact with one surface or another surface of the organic thin film,
Organic thin film
Formula R-SiX ¹ X ² X ³ (I)
(Wherein, R is an organic residue having a π-electron conjugated unit which may be substituted with a functional group at the terminal, and X ¹ , X ² and X ³ are the same or different; It is a group that gives a hydroxyl group by hydrolysis.)
A method for producing an organic thin-film transistor formed as a monomolecular film or a cumulative film using the silicon compound represented by the formula: A substrate, an organic thin film,
A gate electrode formed on one surface of the organic thin film via a gate insulating film,
A method of manufacturing an organic thin film transistor comprising: a source / drain electrode formed on both sides of the gate electrode and in contact with one surface or another surface of the organic thin film,
On the substrate,
Formula R-SiX ¹ X ² X ³ (I)
(Wherein, R is an organic residue having a π-electron conjugated unit which may be substituted with a functional group at the terminal, and X ¹ , X ² and X ³ are the same or different; It is a group that gives a hydroxyl group by hydrolysis.)
A first monomolecular film was formed by a chemisorption method using a silicon compound represented by, and a π-electron conjugated unit was contained on the first monomolecular film by using a chemisorption method. A method for producing an organic thin film transistor, comprising a step of forming at least one second monomolecular film made of a silicon compound.

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