JP2007158147A - Transistor and manufacturing method thereof - Google Patents

Abstract

【Task】
An object of the present invention is to provide a transistor that is practically used in a configuration in which an oxide semiconductor is used as a channel layer and an organic material is used as a gate insulating film, and a manufacturing method thereof.
[Solution]
A semiconductor layer that forms a channel portion on a base material, a source electrode and a drain electrode that are arranged to face each other via the channel portion, and a gate insulating film and the insulating film provided on the semiconductor layer An interface layer including a portion where the gate insulating film is made of an organic material and is chemically adsorbed to the semiconductor layer between the semiconductor layer and the gate insulating film It was solved by providing.
[Selection] Figure 1

Description

  The present invention relates to a transistor using an oxide semiconductor and a manufacturing method thereof.

In general, a thin film transistor using amorphous silicon, polycrystalline silicon, or the like has been used as a transistor for driving an electronic device. However, since high-quality amorphous silicon and polycrystalline silicon require a temperature of 200 ° C. or higher for film formation, it has been difficult to realize a flexible device using a flexible polymer film as a base material.
In recent years, thin film transistors using organic semiconductor materials have been actively studied. The organic semiconductor material can be produced by, for example, a printing process without using a vacuum process. Therefore, the organic semiconductor material can be manufactured at a low temperature, and has an advantage that it is provided on a flexible plastic substrate.
However, organic semiconductor materials have a drawback that they have extremely low mobility and are weak against deterioration over time, and have not yet been widely used and put into practical use.

Based on the above situation, devices using transparent oxide semiconductors have been developed. Transparent oxides can be made at low temperatures and have high mobility. For example, transparent devices can be realized by using transparent materials for substrates, electrodes, insulating films, etc. It has characteristics that were not found in other materials. For example, a field effect transistor using an amorphous In—Ga—Zn—O material has been proposed as the transparent oxide semiconductor (see Non-Patent Document 1).
A transparent field effect transistor having excellent characteristics with a mobility of around 10 cm ² / Vs on a PET substrate at room temperature by using an amorphous oxide semiconductor using the material described in Non-Patent Document 1 as a semiconductor active layer Has been successfully created.
K. Nomura et al. Nature, 432, 488 (2004)

Since the oxide semiconductor can be formed at a low temperature, there is an increased possibility that a transistor using various substrates is obtained.
In a conventional inorganic semiconductor field effect transistor, an inorganic insulating film is used as a gate insulating film, and an interface between the inorganic semiconductor and the gate insulating film is bonded by a covalent bond or an ionic bond.
On the other hand, when an organic insulating film composed of a general organic polymer is used as a gate insulating film of an inorganic semiconductor field effect transistor, unlike the inorganic insulating film, the organic insulating film and the inorganic semiconductor have a strong bond. Absent.
Therefore, when an organic insulating film is used as a gate insulating film, electric charges are generated at the interface between the gate insulating film and the inorganic semiconductor, and application to the gate voltage is insufficient, and adhesion between the organic insulating film and the inorganic semiconductor is insufficient. The strength was insufficient and it was difficult to put it to practical use.

An object of the present invention is to provide a transistor that is practically used in a configuration in which an oxide semiconductor is used as a channel layer and an organic material is used as a gate insulating film, and a manufacturing method thereof.

A semiconductor active layer that forms a channel part on a base material, a source electrode and a drain electrode that are arranged to face each other with the channel part interposed therebetween, a gate insulating film on the semiconductor active layer, and an insulating film interposed therebetween In the semiconductor device comprising the gate electrode provided, the portion of the gate insulating film made of an organic material and chemically adsorbed to the semiconductor active layer between the semiconductor active layer and the gate insulating film It is a semiconductor device characterized by having an interface layer containing.

The semiconductor device according to claim 1, wherein the gate insulating film is an organic polymer.

3. The semiconductor device according to claim 1, wherein the semiconductor layer activity is formed of a compound semiconductor or an oxide semiconductor.

4. The semiconductor device according to claim 3, wherein the oxide semiconductor is a metal oxide semiconductor selected from the group consisting of In, Ga, Zn, and Sn.

The semiconductor device according to claim 1, wherein the interface layer is made of an organic-inorganic composite film.

6. The semiconductor device according to claim 5, wherein the organic-inorganic composite film is a composite film formed from a silane compound.

7. The semiconductor device according to claim 6, wherein the silane compound is one or more silane compounds selected from the group consisting of compounds represented by the following chemical formula (1).

(In the formula, R is independently a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an acrylic group, and an alkyl group, a cycloalkyl group, and an aryl group are an epoxy group, an amino group, a ureido group, a mercapto group, It may be substituted with a sulfide group, an isocyanate group, a styryl group, or an alkyl group, a cycloalkyl group, an aryl group, an epoxy group, an amino group, a ureido group, a mercapto group, a sulfide group, an isocyanate group, or a styryl group. The substituted alkyl group, cycloalkyl group, and aryl group may be perfluorinated or partially fluorinated, and X is independently a halogen atom or an alkoxy group, and n is 0 to 0. 3 represents an integer, m represents an integer of 1 to 4, and n + m = 4.)

The semiconductor device according to claim 1, wherein the interface layer is made of an organic acid.

The semiconductor device according to claim 7, wherein the organic acid is an aliphatic carboxylic acid.

The invention according to claim 10 is:
Forming a source electrode and a drain electrode on a substrate;
Next, a step of forming a semiconductor active layer made of an oxide semiconductor between the source electrode and the drain electrode,
Forming an interface layer on the semiconductor active layer;
Forming a gate insulating film made of an organic material so as to be in contact with the interface layer;
Providing a gate electrode 2 on the gate insulating film;
It is a manufacturing method of the thin-film transistor characterized by having.

The invention according to claim 11 is the method of manufacturing a thin film transistor according to claim 10, wherein the gate insulating film is formed by coating.

The invention according to claim 12 is the method of manufacturing a thin film transistor according to claim 10 or 11, wherein the interface layer is formed of a silane coupling agent.

Since the present invention has the above structure, it has become possible to form a gate insulating film of a transistor using an oxide semiconductor as a semiconductor active layer, in particular, a gate insulating film made of an organic polymer by a wet process.
In this manner, the gate insulating film can be formed with a high throughput and a low temperature process by the wet process.
In addition, since the transistor can be manufactured by a low temperature process, it is possible to manufacture the transistor using a flexible film substrate such as a plastic substrate.

An example of the transistor of the present invention is shown in FIG.
A semiconductor active layer 4 that forms a channel portion on a substrate 1, and a source electrode 8 and a drain electrode 9 that are arranged to face each other with the channel portion interposed therebetween, and a gate insulating film on the semiconductor active layer 4 In the semiconductor device including the gate electrode provided through the insulating film, the gate insulating film is made of an organic material between the semiconductor active layer and the gate insulating film.
The interface layer 7 preferably includes a portion that is chemically adsorbed to the semiconductor active layer.

Here, a substrate such as glass or plastic can be used as the substrate 1, and in particular, a flexible transistor can be provided by using a plastic substrate.
The gate electrode 2 may be a metal thin film such as indium (In), aluminum (Al), gold (Au), silver (Ag), indium oxide (In ₂ O ₃ ), tin oxide (SnO). ₂ ), oxide materials such as zinc oxide (ZnO), cadmium oxide (CdO), indium cadmium oxide (CdIn ₂ O ₄ ), cadmium tin oxide (Cd ₂ SnO ₄ ), zinc tin oxide (Zn ₂ SnO ₄ ) Good.
Moreover, what doped the impurity to the said oxide material is used suitably. For example, In ₂ O ₃ doped with tin (Sn), molybdenum (Mo), titanium (Ti), SnO ₂ doped with antimony (Sb) or fluorine (F), ZnO indium, aluminum, gallium For example, doped with (Ga).

The source electrode 8 and the drain electrode 9 may be made of the same material as the gate electrode 2 or a different material.
In addition, each of the electrodes may be a vacuum deposition method, an ion plating method, a sputtering method, a laser ablation method, a plasma CVD method, a photo CVD method, a hot wire CVD method, or a method such as screen printing using a conductive paste. It is formed using. Each electrode preferably has a film thickness of 15 nm or more.

The semiconductor active layer 4 is an oxide containing one or more elements selected from zinc, indium, tin, tungsten, magnesium, gallium, and oxidized such as zinc oxide, indium oxide, tin oxide, tungsten oxide, zinc gallium indium. However, the present invention is not limited to these.

The interface layer 7 is made of either an organic-inorganic composite film or an organic acid and includes a chemically adsorbed portion.
The organic-inorganic composite film is a composite film formed from a silane compound. Specifically, the silane compound is one or more selected from the group consisting of compounds represented by the following chemical formula (1). It is preferable to use a silane compound.

(In the formula, R is independently a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an acrylic group, and an alkyl group, a cycloalkyl group, and an aryl group are an epoxy group, an amino group, a ureido group, a mercapto group, It may be substituted with a sulfide group, an isocyanate group, a styryl group, or an alkyl group, a cycloalkyl group, an aryl group, an epoxy group, an amino group, a ureido group, a mercapto group, a sulfide group, an isocyanate group, or a styryl group. The substituted alkyl group, cycloalkyl group, and aryl group may be perfluorinated or partially fluorinated, and X is independently a halogen atom or an alkoxy group, and n is 0 to 0. 3 represents an integer, m represents an integer of 1 to 4, and n + m = 4.)
Specifically, alkoxysilanes such as decyltrimethoxysilane and octyltriethoxysilane, alkoxysilanes having an epoxy group such as 3-glycidoxypropyltrimethoxysilane, aminosilanes such as 3-aminopropylsilane, bis (triethoxy Silane having a sulfide group such as (silylpropyl) tetrasulfide, hexyltrichlorosilane, octyltrichlorosilane, and the like.
The interface layer may be formed using an organic acid such as an aliphatic carboxylic acid.

The gate insulating layer 3 is not particularly limited as long as it is an insulating material, but it is preferable to use an insulating film made of an organic material and coated and formed in a wet state.
Specifically, polyimide, polyamide, polyester, polyvinyl phenol, polyvinyl alcohol, polyvinyl acetate, polyurethane, polysulfone, polyvinylidene fluoride, cyanoethyl pullulan, epoxy resin, phenol resin, benzocyclobutene resin, acrylic resin, or the above-mentioned resin A polymer alloy or a copolymer resin can be used.
The insulating film used for the gate insulating layer 13 is made of a resin that can be cured by an electromagnetic wave such as visible light, UV, or EB, a thermosetting resin, or a two-component reaction curable resin after forming a precursor. Can be used.

Next, a method for manufacturing the transistor of the present invention will be described with reference to FIG.
An electrode layer 6 for forming the source electrode 8 and the drain electrode 9 is similarly formed on the base material by a known method such as a sputtering method (see FIG. 2A).
Next, the semiconductor active layer 4 made of an oxide semiconductor is provided on the source electrode 8 and the drain electrode 9 by a known method such as a sputtering method (see FIG. 2B).
Next, an interface layer 7 is formed at the interface of the semiconductor conversion layer 4 (see FIG. 2C).
Next, a known method such as a gate insulating layer 3 sputtering method is provided so as to be in contact with the interface layer 7 (see FIG. 2D).
Here, the interface layer 7 uses a material such as alkoxysilane such as decyltrimethoxysilane or octyltriethoxysilane.
Next, a thin film transistor is obtained by forming the gate electrode 2 on the gate insulating layer 3 by a known method such as sputtering (see FIG. 2E).

The thin film transistor of the present invention can be used in devices such as a liquid crystal display, an organic EL display, a light writing type cholesteric liquid crystal display, a twisting ball type display, a toner display type display, a movable film type display, and a sensor.

First, an aluminum film is formed on a substrate 1 made of PET by a sputtering method, and a source electrode 8 and a drain electrode 9 are formed by using a photolithography method.
Next, a semiconductor active layer 4 made of an InGaZnO oxide semiconductor is formed between the source electrode 8 and the drain electrode 9 by sputtering.
An interface layer 7 was formed on the semiconductor active layer 4, and a gate insulating film 3 made of an epoxy resin was applied and formed so as to be in contact with the interface layer 7.
Next, an aluminum film was formed by a sputtering method, and the gate electrode 2 was provided by using a photolithography method to manufacture a thin film transistor.
In the interface layer 7, the semiconductor active layer is immersed in a solution obtained by dissolving a silane coupling agent (decyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.) in a mixed solvent of water, ethanol, and 1-butanol, and heated at about 100 ° C. This was produced.
As described above, by providing the interface layer between the semiconductor active layer 4 and the gate insulating film 3 made of an organic material, good element characteristics can be obtained even when the organic gate insulating film is used. In addition, since element formation can be performed at a low process temperature, a semiconductor device can be manufactured over a flexible substrate.

FIG. 6 is an explanatory diagram illustrating an example of a transistor of the present invention. FIG. 6 is an explanatory diagram showing an example of a method for manufacturing a transistor of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Base material 2 ... Gate electrode 3 ... Gate insulating layer 4 ... Semiconductor active layer 6 ... Electrode layer 7 ... Interface layer 8 ... Source electrode 9 ... Drain electrode

Claims (12)

A semiconductor active layer that forms a channel part on a base material, a source electrode and a drain electrode that are arranged to face each other with the channel part interposed therebetween, a gate insulating film on the semiconductor layer, and the insulating film In the semiconductor device comprising the provided gate electrode, a portion where the gate insulating film is made of an organic material and is chemically adsorbed to the semiconductor active layer between the semiconductor active layer and the gate insulating film. A semiconductor device comprising an interfacial layer. The semiconductor device according to claim 1, wherein the gate insulating film is an organic polymer. The semiconductor device according to claim 1, wherein the semiconductor active layer is formed of a compound semiconductor or an oxide semiconductor. 4. The semiconductor device according to claim 3, wherein the oxide semiconductor is an oxide semiconductor of a metal selected from the group consisting of In, Ga, Zn, and Sn. The semiconductor device according to claim 1, wherein the interface layer is made of an organic-inorganic composite film. 6. The semiconductor device according to claim 5, wherein the organic-inorganic composite film is a composite film formed from a silane compound. The semiconductor device according to claim 6, wherein the silane compound is one or more silane compounds selected from the group consisting of compounds represented by the following chemical formula (1).

(In the formula, R is independently a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an acrylic group, and an alkyl group, a cycloalkyl group, and an aryl group are an epoxy group, an amino group, a ureido group, a mercapto group, It may be substituted with a sulfide group, an isocyanate group, a styryl group, or an alkyl group, a cycloalkyl group, an aryl group, an epoxy group, an amino group, a ureido group, a mercapto group, a sulfide group, an isocyanate group, or a styryl group. The substituted alkyl group, cycloalkyl group, and aryl group may be perfluorinated or partially fluorinated, and X is independently a halogen atom or an alkoxy group, and n is 0 to 0. 3 represents an integer, m represents an integer of 1 to 4, and n + m = 4.) 4. The semiconductor device according to claim 1, wherein the interface layer is made of an organic acid. The semiconductor device according to claim 7, wherein the organic acid is an aliphatic carboxylic acid. Forming a source electrode and a drain electrode on a substrate;
Next, a step of forming a semiconductor active layer made of an oxide semiconductor between the source electrode and the drain electrode,
Forming an interface layer on the semiconductor active layer;
Forming a gate insulating film made of an organic material so as to be in contact with the interface layer;
Providing a gate electrode 2 on the gate insulating film;
A method for producing a thin film transistor, comprising: 11. The method of manufacturing a thin film transistor according to claim 10, wherein the gate insulating film is formed by coating. 12. The method of manufacturing a thin film transistor according to claim 10, wherein the interface layer is formed of a silane coupling agent.

Images