JP2003258261A - Organic TFT and manufacturing method thereof - Google Patents

Abstract

(57) [Problem] To provide an organic TFT having a high gain. SOLUTION: An organic TFT 10 has a gate electrode 16, a gate insulating film 18 and an organic semiconductor 20 sequentially on a substrate 12, and further has a source electrode 22 and a drain opposed to and separated from the organic semiconductor 20. It has an electrode 24. The substrate 12 is formed of glass. Gate electrode 16 is formed of tantalum. The gate insulating film 18 is formed as a thin and dense film having a high relative dielectric constant by anodizing the gate electrode 16. The organic semiconductor 20 uses pentacene as a material and is formed as a channel having high carrier mobility.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an organic thin film transistor and a method for manufacturing the same.

[0002]

2. Description of the Related Art An organic thin film transistor using an organic material as a semiconductor (hereinafter referred to as an organic TFT) has a manufacturing process which is more than that of a normal thin film transistor using an inorganic material as a semiconductor (hereinafter referred to as an inorganic TFT). It is known that it is simple and the manufacturing cost is low.
In addition, the organic TFT can lower the film forming temperature as compared with the inorganic TFT. Therefore, when the organic TFT is formed on the substrate, the organic TFT can be relatively easily formed without considering the heat resistance of the material of the substrate. There is a feature that a TFT can be formed.

This organic TFT can be suitably used as an active element in an active matrix display, and has been attracting attention as a key device for realizing an active matrix display with high image quality, low power consumption and space saving.

The organic TFT is composed of a gate electrode, a gate insulating film, an organic semiconductor, and a source electrode and a drain electrode. The amount of charge at the interface of the organic semiconductor is changed by the gate voltage Vg to control the drain current I _D for switching. Is.

One of the important factors that influence the performance of the above operation of the organic TFT is the gate insulating film. As the gate insulating film, a metal oxide thin film is generally used.

The gain g _m (dI _D / dV) of the organic TFT
g) is represented by the following formula.

[0007]

[Equation 1] In the equation, W is the channel width, L is the channel length, ε ₀ is the vacuum dielectric constant, ε is the relative dielectric constant of the gate insulating film, d is the thickness of the gate insulating film, and μ is the carrier mobility. , Vt are threshold voltages, respectively.

From the above equation, the smaller the thickness d of the gate insulating film and the larger the relative permittivity ε, the larger the gain g.
It is preferable that _m can be obtained.

[0009]

[Problems to be Solved by the Invention] However, organic T
When the FT is formed on a glass substrate or a plastic substrate, it is necessary to lower the process temperature as compared with the case where it is formed on a silicon substrate. However, an organic TFT that is dense and has good insulating properties at such a low temperature is required. It is generally difficult to form.

For example, some organic TFTs in which an organic semiconductor typified by pentacene is formed on a plastic substrate at room temperature by a vacuum vapor deposition method and a gate insulating film is formed at room temperature by a high frequency sputtering method have been reported. ing. One example uses BZT (Barium Zirconate Titanate) as a material for the gate insulating film (CD Dimitrakopoulos, S.Purushothaman.J.Kymiss).
is, A.Callegari and JMShaw, “low-Voltage Organic
Transistors on Plastic Comprising High-Dielectric C
onstant Gate Insulators ”Science, vol.283,822-824 (1
999)), and another example uses Al ₂ O ₃ as the material for the gate insulating film (JH Schon, S. Berg, Ch.
Kloc, B, Batlogg, “Ambipolar Pentacene Field-Effect
Transistors and Inverters ”Science, Vol.287, pp1022-
1023 (2000)). However, since the process temperature is low in any of the examples, the gate insulating film formed of these metal oxide thin films may have a columnar structure and generate minute pinholes. Since it is difficult to form a gate insulating film, there is a limit to thinning the gate insulating film. Further, even when the high frequency sputtering method is used, it is inevitable that the temperature of the substrate rises to some extent, and thus there is a concern about thermal stress of the plastic substrate.

Further, for example, an example in which the gate insulating film is formed by an application method such as spin coating using an organic material such as polyimide has been reported (Japanese Patent Laid-Open No. 2000-174277). However, when forming a gate insulating film on a plastic substrate by a coating method, a uniform film thickness is formed on the surface of a soft substrate.
In other words, it is not easy to form a gate insulating film having good in-plane uniformity of film thickness, and there is a risk that variations in transistor characteristics will occur.

Further, metal oxide which is the material of the gate insulating film
The material does not necessarily have a high relative permittivity, so
Silicon dioxide (SiO_Two) And silicon nitride (Si
_ThreeN _Four) Have relative permittivity values of 3.9 and 7.
Stop at 5.

Therefore, under the present circumstances, an organic TFT having a high gain g _m is not necessarily realized.

The present invention has been made in view of the above problems, and an object thereof is to provide an organic TFT having a high gain.

[0015]

Means for Solving the Problems Organic TFT according to the present invention
The (organic thin film transistor) is formed on a substrate and is formed by anodizing the surface of the gate electrode in an organic TFT having a gate electrode, a gate insulating film, an organic semiconductor, and a source electrode and a drain electrode. It is characterized by comprising a formed metal oxide film. here,
The gate electrode of the organic TFT is commonly formed of metal.

As a result, a gate insulating film made of a metal oxide film having a self-aligning action in which an electric field is concentrated in a thin portion of the oxide film during the reaction process is formed, thereby forming a gate insulating film by sputtering or vapor deposition. Alternatively, as compared with the case where the gate insulating film is formed by the CVD method or the like, the gate insulating film can be formed in a thin film shape with a small number of pinholes and a high withstand voltage, and an organic TFT having a large gain can be obtained.

In this case, when the organic semiconductor is formed on the source electrode and the drain electrode, it is possible to avoid contamination of the organic semiconductor which may occur when the source electrode and the drain electrode are formed on the organic semiconductor. You can

Further, in this case, when the alignment film is formed on the gate insulating film and the organic semiconductor is formed on the alignment film, the orientation of the organic semiconductor is improved and the carrier mobility is improved. Therefore, an organic TFT having a large gain can be obtained.

In this case, the gate electrode is made of tantalum, aluminum, titanium, niobium, zirconium,
When formed of a single-layer film or a multi-layer film of a material selected from the group consisting of hafnium, chromium, molybdenum, and a molybdenum-tantalum alloy, it is a dense and defective gate insulating film formed by anodizing the gate electrode. It is possible to obtain a film with a small amount. When the gate electrode is a multi-layer film, for example, the gate electrode is a multi-layer film with a metal layer of a component having a coefficient of thermal expansion intermediate between those of the single-layer film gate electrode and the substrate. By doing so, it is possible to reduce stress that may occur due to the difference in the coefficient of thermal expansion between the gate electrode of the single-layer film and the substrate.

In this case, it is preferable that the substrate is made of glass, silicon or plastic. Particularly, in the case of a glass substrate or a plastic substrate, since the organic TFT provided on the substrate can be formed at a relatively low temperature, these substrates having a relatively low heat resistant temperature can be used without any trouble. Further, in particular, in the case of a plastic substrate, since it is flexible and lightweight, it can be suitably used as an active element in an active matrix display, for example.

According to the method of manufacturing an organic TFT of the present invention, the method of manufacturing an organic TFT described above, wherein the gate electrode is anodized to form a gate insulating film,
Based on the relationship between the thickness of the gate insulating film and the applied voltage, which is known in advance, first apply a current (constant current) of a predetermined value, and then when the voltage rises to a predetermined value, the voltage of the predetermined value (constant voltage) Is continuously applied for a predetermined time to obtain a gate insulating film having a predetermined film thickness, the gate insulating film having a predetermined film thickness can be precisely and easily formed.

In this case, the predetermined time is the time from when the application of the voltage of the predetermined value is started until the rate of decrease of the current value per unit time, which decreases with time, reaches the predetermined value. In that case, it is possible to avoid the deterioration of the film quality of the gate insulating film that may occur when a voltage is applied for a longer time than necessary. This predetermined time period is a time period during which sufficient film formation is carried out before the voltage held at the predetermined value undergoes an upward change (aging time).

In the method of manufacturing an organic TFT according to the present invention, when the organic semiconductor is formed on the source electrode and the drain electrode after forming the source electrode and the drain electrode, the organic semiconductor is formed on the organic semiconductor by, for example, a sputtering method. There is no contamination or damage to the organic semiconductor that may occur when the source electrode and the drain electrode are formed.

In the method of manufacturing an organic TFT according to the present invention, if an organic semiconductor is formed on the surface of the alignment film that has been rubbed in a certain direction using a rubbing device after the alignment film is formed, carrier mobility A large organic semiconductor can be obtained.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION A preferred embodiment of an organic TFT and a method for manufacturing the same according to the present invention (hereinafter referred to as the present embodiment) will be described below with reference to the drawings.

An organic TFT according to this embodiment and a method for manufacturing the same will be described with reference to FIGS.

The organic TFT 10 according to this embodiment is
As shown in FIG. 1, a gate electrode 16, a gate insulating film 18 and an organic semiconductor 20 are sequentially provided on a substrate 12,
Further, the source electrode 22 and the drain electrode 24 are arranged on the organic semiconductor 20 so as to face each other and be spaced apart from each other.

The organic TFT 10 having the above structure is manufactured by the following method.

The substrate 12 is formed by using glass as a material.

The gate electrode 16 is made of, for example, tantalum (Ta) as a material, and the power is 200 W and the argon gas pressure is about 3 by, for example, a magnetron DC sputtering method.
About 200 nm on the substrate 12 under the condition of × 10 ⁻¹ Pa
To a film thickness of. Instead of tantalum, the material of the gate electrode 16 may be appropriately selected and used from aluminum, titanium, niobium, zirconium, hafnium, chromium, molybdenum, or molybdenum-tantalum alloy.

The gate insulating film 18 is formed by anodizing the gate electrode 16. In this case, for example, a 1% phosphoric acid aqueous solution is used as the chemical conversion liquid, and the plastic substrate 12 on which the gate electrode 16 is formed is immersed in the chemical conversion liquid. And
By applying a DC electric field between the gate electrode 16 as an anode and a separately prepared cathode, a tantalum pentoxide (Ta ₂ O ₅ ) film as the gate insulating film 18 is formed by the following reaction.

2Ta + 5H_Two0 → Ta_TwoO₅+ 10H⁺
+ E⁻ This tantalum pentoxide film has excellent insulation properties.
Is known to have excellent corrosion resistance during the manufacturing process.
It

At this time, the gate insulating film 18 having a uniform film thickness is formed by the self-alignment action in which the electric field is concentrated on the thin portion of the film during the reaction process.

Further, at this time, in the formation of the film at a constant current, if the increase in the voltage V required to further grow the film thickness D by dD is dV, the differential electric field strength (dV / dD) is the film thickness. Since it does not depend on D and has a substantially constant value, the film thickness of the formed gate insulating film 18 and the set voltage have a substantially proportional relationship as shown in FIG. Therefore, the relationship between the film thickness of the gate insulating film 18 and the set voltage, which are approximated proportionally, is grasped in advance, or the precise film thickness of the gate insulating film 18 for each kind of the material of the gate insulating film 18 is used. By grasping the relationship with the set voltage in advance, the film thickness of the gate insulating film 18 can be accurately and easily controlled by the set voltage value.

At this time, since the degree of progress of the chemical formation is different between the inside and the surface of the film in the process of forming the gate insulating film 18, after reaching the set voltage, a predetermined time (ageing) obtained by studying in advance is reached. The applied state of the set voltage is maintained for (time).

In this case, if the set voltage is continuously applied for a long time, the voltage may increase. It is considered that this phenomenon is caused by the crystallization of the film because a high electric field is applied for a long time. Therefore, in order to prevent this inconvenience, at a predetermined time when the film is formed to have a predetermined film thickness and the current significantly decreases from the predetermined value, in other words, the decrease in the current value almost stops and the current value per unit time is reduced. The formation is terminated when the reduction rate of is a predetermined small value. That is, this time point is set as the end point of the aging time which is the predetermined time. This predetermined time point can be appropriately set by examining the change in the film properties depending on the chemical conversion conditions in advance, and at that time, it is set in consideration of the balance with the ideal aging time.

As an example, for example, 0.1 to 0.25 (m
A voltage is applied with a constant current of about A / cm ² ), and after the voltage reaches a set value of, for example, 50 V, the current value is controlled to 5
The chemical composition is terminated at a predetermined time when the current is remarkably reduced from the predetermined value after the aging time while maintaining the set voltage of 0V. As a result, the thin gate insulating film 18 having a thickness of 85.64 nm can be obtained accurately and easily.

The gate insulating film 18 is formed by the above anodic oxidation method.
After forming, the substrate 12 is washed with, for example, pure water, and is baked at a temperature of about 70 ° C.

The organic semiconductor 20 uses, for example, pentacene as a material, the pressure of the chamber is set to, for example, 10 ⁻⁵ Pa by a vacuum vapor deposition method by resistance heating, and the substrate temperature is within a range of room temperature to 100 ° C. The insulating film is formed to have a film thickness of 50 nm, for example. At this time, the length (channel length) L of the organic semiconductor in the direction between the source electrode and the drain electrode is formed to 0.5 mm, and the width (channel width) W of the organic semiconductor is formed to 10 mm, for example.

Source electrode 22 and drain electrode 24
Is, for example, Au as a material,
For example, 100 on the organic semiconductor 20 through the metal mask.
It is formed in a strip shape with a film thickness of nm.

The organic TFT 10 according to this embodiment is
Since the gate insulating film 18 is formed by oxidizing the gate electrode 16 made of tantalum by the anodic oxidation method,
The gate insulating film 18 can be formed in a thin film shape having a small number of pinholes and a high withstand voltage as compared with the conventional case formed by a sputtering method, a vapor deposition method, a CVD method or the like, and an organic TFT having a large gain can be obtained. You can

The organic TFT 1 according to the present embodiment example
In No. 0, glass was used as the material of the substrate 12, but instead of this, silicon may be used or plastic may be used. Particularly, in the case of a glass substrate or a plastic substrate, since the organic TFT provided on the substrate can be formed at a relatively low temperature, these substrates having a relatively low heat resistant temperature can be used without any trouble. Further, in particular, in the case of a plastic substrate, since it is flexible and lightweight, it can be suitably used as an active element in an active matrix display, for example.

In the organic TFT 10, the substrate 12
If a tantalum layer is formed after forming an aluminum layer on the gate electrode 16 and the gate electrode 16 is a multilayer film of tantalum and aluminum, when the gate electrode is only the tantalum layer, the heat of the tantalum layer and the substrate 12 is reduced. It is possible to reduce stress that may occur due to the different expansion rates. This effect is remarkable when a plastic having a particularly large coefficient of thermal expansion is used as the substrate material.

With respect to the organic TFT 10 according to the present embodiment, the physical properties of the gate insulating film 18 were measured, and the result was 1 kHz.
The capacitance of the capacitor measured by z is 0.248 (uF / cm
² ), and the relative dielectric constant obtained from this was about 24. The value of the relative permittivity of the gate insulating film 18 is considerably larger than the relative permittivity of 3.9 of conventional silicon dioxide and the relative permittivity of 7.5 of silicon nitride. Further, as described above, the gate insulating film 18 has a small film thickness of 85.64 nm.

As described above, the organic semiconductor 20 has a width (channel width W) of 10 mm and a length (channel length L) of 0.5 mm, and the ratio (W / L) is 20.
And big. The organic semiconductor 20 has a large carrier mobility (μ) of about 0.22 (cm ² / V · s).

FIG. 4 shows the results of measuring the static characteristics of the organic TFT 10 in which the gate insulating film 18 and the organic semiconductor 20 have the above characteristics. The organic TFT 10 has a large gain and operates at a low threshold voltage with a gate voltage Vg of about 1.2V.

Next, the organic TFT 10 according to the present embodiment example.
A modified example will be described. In each of the following modifications, the same components as those of the organic TFT 10 are designated by the same reference numerals as those of the organic TFT 10 and duplicate description is omitted.

The organic TFT 10a according to the first modification is
As shown in FIG. 5, the gate insulating film 18 and the organic semiconductor 20 are formed.
The organic TFT is that the alignment film 30 is provided between
Different from 10.

For example, by a spin coating method or a printing method,
A polymer having a long-chain alkyl group dissolved in an organic solvent is thinly applied on the gate insulating film 18, dried, and then the surface of the formed film is rubbed with a rubbing device to align vertically. That is, the gate insulating film 18
The alignment film 30 in which the polymers having long-chain alkyl groups are aligned vertically is obtained. Then, on the alignment film 30,
By forming a thin film of pentacene by the vacuum deposition method described above, the molecules of pentacene are vertically aligned,
That is, the organic semiconductor 20a in which pentacene molecules are aligned upright between the alignment film 30 and the source electrode 22 and the drain electrode 24 is obtained.

In the organic TFT 10a, the orientation of the organic semiconductor 20a is improved, and the carrier mobility (μ) is 1.1 (cm).
^Since it is as large as ² / V · s), a large gain can be obtained.

The organic TFT 10b according to the second modification is
As shown in FIG. 6, the organic semiconductor 20b is different from the organic TFT 10 in that the organic semiconductor 20b is provided on the source electrode 22a and the drain electrode 24a.

In this case, the gate insulating film 18a is formed so as to cover not only the upper surface of the gate electrode 16a but also the side surface thereof. Then, next to the gate insulating film 18a, the source electrode 22a and the drain electrode 24a are formed. At this time, the source electrode 22a and the drain electrode 24a are
The gate electrodes 16a covered with the gate insulating film 18a are formed so as to be spaced from each other with the gate electrode 16a interposed therebetween and to face each other on the plastic substrate 12. Source electrode 22a and drain electrode 2
4a is obtained by vacuum vapor deposition through a metal mask as described above, or by vacuum vapor deposition through a resist mask formed by patterning by photolithography instead of the metal mask when performing fine processing. can get. The source electrode 22a and the drain electrode 24a are insulated by the gate insulating film 18a, and the source electrode 22a and the drain electrode 24a are
As long as the two conditions that at least a part of the organic semiconductor 20b is interposed between the two, a laminated structure other than that shown in FIG. 8 can be formed.

Next, the organic semiconductor 20b is connected to the source electrode 22a and the drain electrode 2 by the above-mentioned vacuum deposition method or the like.
It is formed on 4a. At this time, part of the organic semiconductor 20b is formed so as to enter the gap between the source electrode 22a and the drain electrode 24a and the gate insulating film 18a. However, the invention is not limited to this, and the source electrode 22a and the drain electrode 24a and the gate insulating film 18a may be adhered to each other.

In the case of forming an organic semiconductor on the source electrode and the drain electrode in place of the above-described structure of the organic TFT 10b and the manufacturing method thereof, heat and impurities when forming the source electrode and the drain electrode by the vacuum evaporation method may be used. However, the previously formed organic semiconductor may be damaged or contaminated, and the characteristics of the organic TFT may be deteriorated. Also,
When patterning by lithography, the surface of the organic semiconductor is similarly contaminated by immersing the plastic substrate 12 on which the organic semiconductor is formed in the uppermost layer in a resist or etchant (etching solution) which is an organic material. The characteristics may deteriorate.

On the other hand, according to the above-mentioned structure of the organic TFT 10b and the manufacturing method thereof, there is no fear that the organic semiconductor 20b is contaminated and the like, and therefore the organic T
There is no fear that the characteristics of the FT 10b will deteriorate. Further, in this case, the same process as that of the inorganic TFT can be adopted until the source electrode 22a and the drain electrode 24a are formed, and the manufacturing method is not complicated.

[0056]

According to the organic TFT of the present invention, since the gate insulating film is a metal oxide film formed by anodizing the surface of the gate electrode, it is a thin film with few pinholes and excellent in withstand voltage. The gate insulating film can be formed in a uniform shape, and an organic TFT having a large gain can be obtained.

According to the organic TFT of the present invention,
Since the organic semiconductor is formed on the source electrode and the drain electrode, it is possible to avoid contamination of the organic semiconductor that may occur when the source electrode and the drain electrode are formed on the organic semiconductor.

According to the organic TFT of the present invention,
Since the alignment film is formed on the gate insulating film and the organic semiconductor is formed on the alignment film, carrier mobility is improved, and an organic TFT having a large gain can be obtained.

According to the organic TFT of the present invention,
Since the gate electrode is formed of a single-layer film or a multi-layer film of a material selected from the group consisting of tantalum, aluminum, titanium, niobium, zirconium, hafnium, chromium, molybdenum and molybdenum-tantalum alloy, the gate electrode is As a gate insulating film formed by anodic oxidation, a denser film with less defects can be obtained.

According to the organic TFT of the present invention,
It is preferable because the substrate is made of glass, silicon or plastic.

According to the organic TFT of the present invention,
In the method for manufacturing an organic TFT described above, in manufacturing a gate insulating film by anodizing a gate electrode, based on the relationship between the thickness of the gate insulating film and the applied voltage, which is grasped in advance,
First, a current of a predetermined value is passed, and then, when the voltage rises to a predetermined value, the application of the voltage of the predetermined value is continued for a predetermined time,
Since the gate insulating film having a predetermined thickness is obtained, the gate insulating film having a predetermined thickness can be precisely and easily formed.

According to the organic TFT of the present invention,
The predetermined time is the time between the start of applying the voltage of the predetermined value and the decrease rate of the current value per unit time that decreases with the passage of time until it reaches the predetermined value. It is possible to avoid the deterioration of the film quality of the gate insulating film that may occur when a voltage is applied over time.

Further, according to the method of manufacturing an organic TFT of the present invention, since the organic semiconductor is formed on the source electrode and the drain electrode after forming the source electrode and the drain electrode, for example, the sputtering method is applied on the organic semiconductor. Therefore, the organic semiconductor is not contaminated or damaged, which may occur when the source electrode and the drain electrode are formed.

Further, according to the method of manufacturing an organic TFT of the present invention, after the alignment film is formed, the organic semiconductor is formed on the surface of the alignment film which is rubbed in a certain direction by using a rubbing device. An organic semiconductor having high mobility can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an organic TFT according to an embodiment of the present invention.

FIG. 2 is a graph showing a relationship between an applied voltage and a film thickness when a gate insulating film is formed by an anodic oxidation method.

FIG. 3 is a graph showing changes over time in current and voltage when forming a gate insulating film by an anodic oxidation method.

FIG. 4 is a graph showing static operation characteristics of the organic TFT of this embodiment.

FIG. 5 is a diagram showing a schematic configuration of an organic TFT of a first modified example.

FIG. 6 is a diagram showing a schematic configuration of an organic TFT of a second modified example.

[Explanation of symbols]

10, 10a, 10b Organic TFT 12 substrates 16, 16a Gate electrode 18, 18a Gate insulating film 20, 20a, 20b Organic semiconductor 22, 22a Source electrode 24, 24a drain electrode 30 Alignment film

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 51/00 H01L 29/28 (72) Inventor Yoji Inoue 1-10-11 Kinuta, Setagaya-ku, Tokyo Japan Broadcasting Association Broadcasting Technology Research Institute (72) Inventor Shizushi Tokki 1-10-11 Kinuta, Setagaya-ku, Tokyo Inside Broadcasting Technology Research Institute (72) Japan Broadcasting Corporation Hiroshi Kikuchi 1-10 Kinuta, Setagaya-ku, Tokyo No. 11 Japan broadcasting Association of broadcasting technology Institute in the F-term (reference) 4M104 AA09 BB02 BB13 BB16 BB17 CC05 DD37 DD89 EE03 GG09 5F058 BA01 BB07 BC03 BF70 BH01 BJ04 5F110 AA07 AA17 BB01 CC03 DD01 DD02 DD13 EE03 EE04 EE14 EE44 FF01 FF05 FF09 FF24 FF36 GG05 GG06 GG25 GG28 GG29 GG42 HK02 HK32

Claims (9)

[Claims] 1. An organic TFT formed on a substrate and having a gate electrode, a gate insulating film, an organic semiconductor, and a source electrode and a drain electrode, wherein the gate insulating film is formed by anodizing the surface of the gate electrode. Organic T characterized by comprising a metal oxide film
FT. 2. The organic TFT according to claim 1, wherein the organic semiconductor is formed on the source electrode and the drain electrode. 3. The organic TFT according to claim 1, wherein an alignment film is formed on the gate insulating film, and the organic semiconductor is formed on the alignment film. 4. The gate electrode is formed of a single-layer film or a multi-layer film of a material selected from the group consisting of tantalum, aluminum, titanium, niobium, zirconium, hafnium, chromium, molybdenum and a molybdenum-tantalum alloy. It becomes any one of Claims 1-3 characterized by the following.
An organic TFT according to item. 5. The substrate is formed of glass, silicon or plastic.
5. The organic TFT according to any one of 4 to 4. 6. The method of manufacturing an organic TFT according to claim 1, wherein when a gate insulating film is manufactured by anodizing a gate electrode, a relationship between a film thickness of the gate insulating film and an applied voltage which is grasped in advance is set. Based on this, a current of a predetermined value is first supplied, and then, when the voltage rises to a predetermined value, application of the voltage of the predetermined value is continued for a predetermined time to obtain a gate insulating film having a predetermined film thickness. Method of manufacturing organic TFT. 7. The predetermined time is a time from when the application of the voltage of the predetermined value is started until the rate of decrease of the current value per unit time, which decreases with time, reaches a predetermined value. The method for producing an organic TFT according to claim 6, wherein 8. The method of manufacturing an organic TFT according to claim 2, wherein after forming the source electrode and the drain electrode, an organic semiconductor is formed on the source electrode and the drain electrode. Manufacturing method. 9. The method of manufacturing an organic TFT according to claim 3, wherein after forming the alignment film, an organic semiconductor is formed on the surface of the alignment film rubbed in a certain direction by using a rubbing device. A method of manufacturing a characteristic organic TFT.