JP2005158775A - Manufacturing method of organic thin film field effect transistor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an organic thin film field effect transistor having higher degree of freedom in selection of a substrate which can manufacture an organic thin film field effect transistor having higher element performance and can simplify the manufacturing process. <P>SOLUTION: A source electrode 5 and a drain electrode 6 are formed on the basis of a photoresist pattern 8a which is formed by radiating the ultraviolet ray U to the photoresist 8 from the rear surface of the glass substrate 2 using the gate electrode 3 as the mask pattern. Thereafter, an organic semiconductor layer 7 is evaporated and the organic semiconductor layer 7 is patterned to the insulating film 4 exposed after the photoresist pattern 8a is removed and is left at the area near such insulating film 4. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing an organic thin film field effect transistor, and more particularly to a method for manufacturing an organic thin film field effect transistor by self-alignment.

  2. Description of the Related Art Conventionally, various methods for manufacturing a thin film transistor, which is one of elements constituting an integrated circuit, have been proposed along with the high integration of the integrated circuit. There is a photolithography technique as a manufacturing method that is generally used. Photolithographic technology, for example, by forming a photoresist film on a substrate, irradiating ultraviolet rays through a mask in which a desired pattern is formed on the photoresist film, transferring the mask pattern to the photoresist film, and developing it, A photoresist pattern is formed based on the mask pattern. Next, a metal thin film is formed over the entire surface of the substrate and the resist film, and an electrode having a desired pattern is formed by lifting off the photoresist pattern and the metal thin film formed on the photoresist pattern.

  In the process of manufacturing the thin film transistor, the process of transferring the mask pattern to the resist film is performed at least twice in the process of patterning the gate electrode and the process of patterning the source electrode and the drain electrode. Therefore, when transferring the pattern of the electrode to be patterned later, a mask alignment process is required to accurately determine the position of the mask so that the relative position with respect to the pattern of the electrode patterned earlier is not shifted. However, with the miniaturization of thin film transistors, very high accuracy is required for the mask alignment process. If the mask alignment is performed, the relative position of the subsequent mask with respect to the pattern of the previously patterned electrode is required. If the deviation occurs, the device performance is degraded due to parasitic capacitance and resistance.

Therefore, in recent years, a self-alignment technique capable of manufacturing a thin film transistor without mask alignment has been proposed. For example, in the method of manufacturing a thin film transistor by self-alignment described in Non-Patent Document 1, a gate electrode is patterned on a glass substrate capable of transmitting ultraviolet rays, and an SiO ₂ layer (insulating layer), an amorphous silicon thin film, a resist film is formed thereon. Next, using the gate electrode as a mask pattern and irradiating ultraviolet rays from the back surface of the glass substrate to form a photoresist pattern, patterning the source electrode and the drain electrode based on the photoresist pattern, Amorphous silicon constituting the channel is deposited on the amorphous silicon exposed between the source electrode and the drain electrode. That is, since the pattern of the gate electrode that has been patterned first is exposed as a mask pattern, the mask alignment process can be eliminated, and the gate electrode that has been formed first and the source electrode that is patterned later. And the relative position with respect to the drain electrode can be positioned accurately.
IEEE ELECTRON DEVICE LETTERS, VOL.EDL-3 NO.7, JULY 1982 (page 1, page 2, Fig. 1)

However, in order to form a channel with amorphous silicon, it is difficult to deposit amorphous silicon directly on the SiO ₂ layer on which the source electrode and the drain electrode are formed. Therefore, before forming the source electrode and the drain electrode, SiO 2 is formed. A thin film of amorphous silicon must be formed on the _two layers, resulting in problems such as complicated process and longer time. Since amorphous silicon is formed on the SiO ₂ layer, the back-exposed ultraviolet rays are blocked by the amorphous silicon thin film, resulting in a problem that the exposure time is prolonged.

  In order to deposit an inorganic semiconductor such as amorphous silicon, it is necessary to heat the substrate to several hundred degrees, so a material that can withstand several hundred degrees must be selected for the substrate, and the degree of freedom of the material of the substrate Is very low. In particular, a display using organic EL can be made of a flexible material such as a synthetic resin on a substrate, so that a deformable display can be produced. It is very difficult to apply the thin film transistor constituted by the above.

  An object of the present invention is to provide an organic thin film field effect transistor manufacturing method capable of manufacturing an organic thin film field effect transistor with high device performance, simplifying the process, and increasing the degree of freedom of substrate selection. It is to provide.

  An organic thin film field effect transistor manufacturing method according to claim 1, comprising: a first electrode; a second electrode; and an organic semiconductor layer constituting a channel; and an organic thin film formed on a transparent substrate. In the method of manufacturing a field effect transistor, in order to form the second electrode, a photoresist pattern is formed by irradiating light from the back surface of the substrate using the pattern of the first electrode as a mask pattern.

  According to this method of manufacturing an organic thin film field effect transistor, a first electrode pattern formed on the substrate surface is used as a mask pattern to irradiate light from the back surface of the substrate to form a photoresist pattern. A second electrode is formed based on the pattern. Therefore, since the relative position between the first electrode and the second electrode can be accurately determined, the generation of parasitic resistance and parasitic capacitance, which are the cause of element performance, can be suppressed almost. Since the organic semiconductor layer constituting the channel can be formed at a low temperature, the substrate can be made of various materials. The organic semiconductor layer does not require a base such as amorphous silicon and can be directly formed, and thus the process of the method for manufacturing the organic thin film field effect transistor can be simplified. Since there is nothing other than the first electrode that blocks light when irradiating light, the light irradiation time can be shortened.

  3. The method of manufacturing an organic thin film field effect transistor according to claim 2, wherein a first step of patterning a gate electrode on a substrate surface capable of transmitting light, and a second step of forming an insulating film on the gate electrode. And a third step of forming a photoresist pattern on the insulating film, using the gate electrode pattern as a mask pattern, and irradiating the photoresist film with light from the back of the substrate to form a photoresist pattern; and A fourth step of forming a source electrode and a drain electrode based on the pattern, and a fifth step of forming an organic semiconductor layer between the source electrode and the drain electrode.

  According to this method of manufacturing an organic thin film field effect transistor, the gate electrode is patterned on the substrate surface in the first step, and in the third step, the gate electrode pattern is used as a mask pattern and the photoresist film is applied to the photoresist film from the back surface. A photoresist pattern is formed by irradiating light, and in the fourth step, a source electrode and a drain electrode are formed based on the photoresist pattern, and in a fifth step, exposure is performed between the source electrode and the drain electrode. An organic semiconductor layer is formed on the insulating film.

In this manner, a photoresist pattern is formed using the gate electrode as a mask pattern, and the source electrode and the drain electrode are formed based on the photoresist pattern. Therefore, the relative position of the source electrode and the drain electrode with respect to the gate electrode is accurately positioned. Generation of parasitic resistance and capacitance can be greatly reduced.
Since the organic semiconductor layer forming the channel formed between the source electrode and the drain electrode can be formed at a low temperature, the degree of freedom of a material applicable to the substrate is greatly increased. Since the organic semiconductor layer can be directly formed on the insulating film, the process of the method for manufacturing the organic thin film field effect transistor can be simplified. Since there is nothing other than the gate electrode that blocks light when irradiating light, the light irradiation time can be shortened.

  The method of manufacturing an organic thin film field effect transistor according to claim 3, wherein a first step of patterning a source electrode and a drain electrode on a substrate surface capable of transmitting light is provided between the source electrode and the drain electrode. A second step of forming an organic semiconductor layer; a third step of forming an insulating film on the organic semiconductor layer; forming a photoresist film on the insulating film; and masking a pattern of the source electrode and the drain electrode A fourth step of forming a photoresist pattern by irradiating the photoresist film with light from the back surface of the substrate, and a fifth step of forming a gate electrode based on the photoresist pattern. .

  According to this method of manufacturing an organic thin film field effect transistor, the source electrode and the drain electrode are patterned on the substrate surface in the first step, and exposed between the source electrode and the drain electrode in the second step. An organic semiconductor layer is formed on the substrate, and in the third step, the pattern of the source electrode and drain electrode is used as a mask pattern, and a photoresist pattern is formed by irradiating the photoresist film with light from the back of the substrate. In this step, a gate electrode is formed based on this photoresist pattern.

As described above, since the gate electrode is formed based on the photoresist pattern formed using the pattern of the source electrode and the drain electrode as a mask pattern, the relative position of the gate electrode with respect to the source electrode and the drain electrode can be accurately positioned. The generation of parasitic resistance and parasitic capacitance can be greatly reduced.
Since the organic semiconductor layer forming the channel formed between the source electrode and the drain electrode can be formed at a low temperature, the degree of freedom of a material applicable to the substrate is greatly increased. Since the organic semiconductor layer can be directly formed on the substrate, the steps of the method for manufacturing the organic thin film field effect transistor can be simplified. When there is no light other than the source electrode and the drain electrode when irradiating light, the light irradiation time can be shortened.

  According to a fourth aspect of the present invention, in the method for manufacturing an organic thin film field effect transistor according to any one of the second to third aspects, the light irradiated from the back surface is ultraviolet light. According to this method for manufacturing an organic thin film field effect transistor, since a photoresist pattern is formed by irradiating ultraviolet rays from the back surface, the ultraviolet rays irradiated to the back surface of each electrode as a mask pattern hardly wrap around. Therefore, a photoresist pattern having almost the same pattern as that of each electrode can be formed.

  The method for producing an organic thin film field effect transistor according to claim 5 is the method according to any one of claims 2 to 4, wherein the organic semiconductor layer is formed before the organic semiconductor layer is formed. A first cleaning step for cleaning contaminants is provided. According to this method of manufacturing an organic thin film field effect transistor, organic contaminants are cleaned where the organic semiconductor layer is formed. Therefore, even if the organic semiconductor layer is formed directly on the substrate, insulating film, and electrode, Organic contaminants do not enter the semiconductor layer.

  The method of manufacturing an organic thin film field effect transistor according to claim 6 is the method according to any one of claims 2 to 5, wherein the heavy metal at a position where the organic semiconductor layer is formed before the organic semiconductor layer is formed. And a second cleaning step for cleaning the alkali metal. According to this method for manufacturing an organic thin film field effect transistor, the heavy metal and alkali metal at the place where the organic semiconductor layer is formed are washed, so even if the organic semiconductor layer is formed directly on the substrate, insulating film, and electrode, Generation of mobile ions in the organic semiconductor layer can be greatly reduced.

  A manufacturing method of an organic thin film field effect transistor according to a seventh aspect is the invention according to any one of the second to sixth aspects, wherein the organic semiconductor layer is made of pentacene. According to this method for manufacturing an organic thin film field effect transistor, since the organic semiconductor layer is made of pentacene having a high carrier mobility, the element performance of the organic thin film field effect transistor can be improved.

  The method of manufacturing an organic thin film field effect transistor according to claim 8 is the method according to any one of claims 2 to 7, wherein each of the gate electrode, the source electrode, and the drain electrode is Ta, Cr, Al, Ti, Ni. Cu, Mo, Pd, Ag, In, Sn, Er, W, Pt, or Au. According to the method of manufacturing the organic thin film field effect transistor, the same effects as in the second to seventh aspects can be achieved.

  The method for producing an organic thin film field effect transistor according to claim 9 is the method according to any one of claims 2 to 7, wherein each of the source electrode and the drain electrode is Ta, Cr, Al, Ti, Ni, Cu, Mo. , Pd, Ag, In, Sn, Er, W, Pt, and Au are used to form a two-layer structure of two kinds of metals. According to the method of manufacturing the organic thin film field effect transistor, the same effects as in the second to seventh aspects can be achieved.

  A method of manufacturing an organic thin film field effect transistor according to claim 10 is the method according to any one of claims 2 to 7, wherein the gate electrode is made of Ta or Al and anodized before forming the insulating film. Is. According to the method of manufacturing the organic thin film field effect transistor, the same effects as in the second to seventh aspects can be achieved.

  An organic thin film field effect transistor manufacturing method according to an eleventh aspect of the present invention is the method according to any one of the second to seventh aspects, wherein the gate electrode is made of a conductive polymer. According to the method of manufacturing the organic thin film field effect transistor, the same effects as in the second to seventh aspects can be achieved.

  According to a twelfth aspect of the present invention, there is provided a method for manufacturing an organic thin film field effect transistor according to any one of the second to eleventh aspects, wherein the insulating film is made of an inorganic material. According to the method of manufacturing the organic thin film field effect transistor, the same effects as in the second to eleventh aspects can be achieved.

The method for manufacturing an organic thin film field effect transistor according to claim 13 is the invention of claim 12, wherein the insulating film _{SiO 2, SiN, Al 2 O} 3, Ta 2 O 5, SiON, the P ₂ O ₅ It consists of either. According to this method of manufacturing an organic thin film field effect transistor, the same effect as in the twelfth aspect can be achieved.

  A method for producing an organic thin film field effect transistor according to claim 14 is the method according to any one of claims 2 to 11, wherein the insulating film is made of an organic material. According to the method of manufacturing the organic thin film field effect transistor, the same effects as in the second to eleventh aspects can be achieved.

  According to a fifteenth aspect of the present invention, in the method for manufacturing an organic thin film field effect transistor according to the fourteenth aspect, the insulating film is made of any one of polyparaxylylene, parylene, and polyvinylphenol. According to this method of manufacturing an organic thin film field effect transistor, the same effect as that of the invention of claim 14 can be attained.

  The method for producing an organic thin film field effect transistor according to claim 16 is the method according to any one of claims 2 to 15, wherein a protective layer is formed on the uppermost surface of the organic thin film field effect transistor. According to the method of manufacturing the organic thin film field effect transistor, the same operation as in the second to fifteenth aspects can be achieved.

The method for manufacturing an organic thin film field effect transistor according to claim 17 is the invention of claim 16, GeO _X the protective layer, SiO _X, the organic insulating film, polyparaxylylene, parylene, any polyvinylphenol It is what consists of. According to the method for manufacturing the organic thin film field effect transistor, the same effect as in the sixteenth aspect can be attained.

The organic thin film field effect transistor manufactured by the method of manufacturing an organic thin film field effect transistor according to claim 1 can reduce a signal voltage loss such as charge distribution by reducing a parasitic capacitance, thereby improving a writing level. be able to. Further, the drive current can be increased by reducing the parasitic resistance. Since the relative position between each electrode can be accurately determined, the organic thin film field effect transistor can be reduced in size, and as this downsizing, the vacant area on the substrate increases. The channel width of the effect transistor can be increased, and the driving capability can be improved.
By configuring the channel with an organic semiconductor layer, the degree of freedom of substrate selection is widened, so a synthetic resin of a flexible material can be applied to the substrate, and by configuring an organic EL display with such a substrate, A flexible display can be manufactured.

The organic thin film field effect transistor manufactured by the method for manufacturing an organic thin film field effect transistor according to claim 2 can achieve the same effect as that of the invention of claim 1.
The organic thin film field effect transistor produced by the method for producing an organic thin film field effect transistor according to claim 3 can achieve the same effects as the invention of claim 1.

Since the organic thin film field effect transistor manufactured by the method of manufacturing an organic thin film field effect transistor according to claim 4 has almost no ultraviolet light wraps around the back surface of each electrode, the electrodes hardly overlap each other. Generation of parasitic capacitance can be further reduced, and problems such as a decrease in signal voltage loss due to electrification distribution and a phenomenon of change in write level can be solved. In addition, the same effects as in the second to third aspects can be achieved.
The organic thin film field effect transistor manufactured by the method of manufacturing an organic thin film field effect transistor according to claim 5 has almost no organic contaminants mixed in the organic semiconductor layer. The device performance can be improved. In addition, the same effects as those of claims 2 to 4 can be achieved.

The organic thin film field effect transistor manufactured by the method for manufacturing an organic thin film field effect transistor according to claim 6 can improve device performance without mobile ions being mixed into the organic semiconductor layer. In addition, the same effects as those of claims 2 to 5 can be achieved.
In the manufacturing method of the organic thin film field effect transistor according to the seventh aspect, since pentacene having high carrier mobility is applied to the organic semiconductor layer, the element performance of the organic thin film field effect transistor can be improved. In addition, the same effects as those of claims 2 to 6 can be obtained.

According to the method for manufacturing an organic thin film field effect transistor according to claim 8, the same effects as in claims 2 to 7 can be obtained.
According to the method for manufacturing an organic thin film field effect transistor according to claim 9, the same effects as in claims 2 to 7 can be obtained.
According to the method for producing an organic thin film field effect transistor according to claim 10, the same effects as in claims 2 to 7 can be obtained.

According to the method for manufacturing an organic thin film field effect transistor according to claim 11, the same effects as in claims 2 to 7 can be obtained.
According to the method for producing an organic thin film field effect transistor according to claim 12, the same effects as in claims 2 to 11 can be achieved.
According to the method for manufacturing an organic thin film field effect transistor according to claim 13, the same effect as in claim 12 can be obtained.

According to the method for manufacturing an organic thin film field effect transistor according to claim 14, the same effects as in claims 2 to 11 can be obtained.
According to the method for producing an organic thin film field effect transistor according to claim 15, the same effect as in claim 14 can be achieved.
According to the method for manufacturing an organic thin film field effect transistor according to claim 16, the same effects as in claims 2 to 15 can be achieved.
According to the method for manufacturing an organic thin film field effect transistor according to claim 17, the same effect as in claim 16 can be obtained.

  According to the present invention, there is provided an organic thin film field effect transistor manufacturing method capable of manufacturing an organic thin film field effect transistor having high device performance, simplifying a process, and increasing a degree of freedom in selecting a substrate. An object of the present invention is to provide a method for producing an organic thin film field effect transistor comprising a first electrode, a second electrode, and an organic semiconductor layer constituting a channel, and formed on a transparent substrate. In order to form a photoresist pattern, the first electrode pattern is used as a mask pattern to irradiate light from the back surface of the substrate to form a photoresist pattern.

Embodiments of the present invention will be described below with reference to the drawings.
This embodiment is an example in which the present invention is applied to a manufacturing method of an inverted stagger type organic thin film field effect transistor which can be applied to an active matrix type TFT of an organic EL display having a channel constituted by an organic semiconductor. This corresponds to the invention of claim 2.

First, the configuration of an inverted staggered organic thin film field effect transistor 1 (hereinafter referred to as TFT) will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view of the TFT 1, but the aspect ratio and the thickness ratio of each layer in FIG. 1 are changed for convenience, unlike the actual ratio.
The TFT 1 is formed on an insulating glass substrate 2 that can transmit ultraviolet rays U. The TFT 1 includes a gate electrode 3, an insulating film 4, a source electrode 5, a drain electrode 6, and an organic semiconductor layer 7.

The gate electrode 3 is made of tantalum and is formed by patterning on the surface of the glass substrate 2 with a thickness of about 50 nm. The insulating film 4 is made of Al ₂ O ₃ and has a thickness of about 200 nm and is formed on the surface of the glass substrate 2 and the surface of the gate electrode 3.
Both the source electrode 5 and the drain electrode 6 have a two-layer structure, in which the lower layer is made of Cr 5a, 6a having a thickness of about 10 nm and the upper layer is made of Au 5b, 6b having a thickness of about 50 nm. The source electrode 5 and drain electrode 6, the channel length C _L of about 6 [mu] m, are patterned such that the channel width of about 700 .mu.m. The source electrode 5 and the gate electrode 3, and the drain electrode 6 and the gate electrode 3 are formed so as to overlap D = about 0.8 μm in the left-right direction on the paper surface, but are formed at these overlapping portions. The parasitic capacitance is very small and has almost no effect on the element performance of TFT1.
The organic semiconductor layer 7 constitutes a channel, is composed of pentacene having a carrier mobility of about 1 cm ² / Vs, and is exposed between the source electrode 5 and the drain electrode 6 with a thickness of about 100 nm. It is formed on the insulating film 4 and in the vicinity thereof.

Next, a manufacturing method of the TFT 1 will be described with reference to FIG.
First, in the gate electrode formation step, a tantalum thin film constituting the gate electrode 3 is formed to a thickness of about 50 nm by sputtering over the entire surface of the cleaned glass substrate 2. Next, the tantalum thin film is patterned by photolithography to form the gate electrode 3. Next, the glass substrate 2 together with the gate electrode 3 is washed with boiled nitric acid at 80 ° C. for 10 minutes, and further washed with boiled sulfuric acid at 130 ° C. for 10 minutes (corresponding to the first step).

Next, in the insulating film forming step, an Al ₂ O ₃ layer is formed with a thickness of about 200 nm by electron beam evaporation, and then the Al ₂ O ₃ layer is patterned to form a glass on the gate electrode 3 and in the vicinity of the gate electrode 3. An insulating film 4 is formed on the substrate 2 (corresponding to the second step).
Next, in a photoresist pattern forming step, polyimide is applied to a thickness of about 1 μm by spin coating, and a positive photoresist film 8 is formed over the entire surface such as the insulating film 4 or the exposed glass substrate 2. Form. Next, using the pattern of the gate electrode 3 as a mask pattern, the pattern of the gate electrode 3 is transferred to the photoresist film 8 by irradiating the photoresist film 8 with parallel light of ultraviolet rays U from the back surface of the glass substrate 2 using a Hg lamp. (FIG. 2-1).

  Next, the photoresist film 8 is developed with a dedicated organic alkali developer to form a photoresist pattern 8 a having a pattern substantially the same as the pattern of the gate electrode 3. However, since the irradiated ultraviolet ray U wraps inward above the gate electrode 3, both ends of the patterned photoresist pattern 8 a in the left-right direction on the paper surface are approximately 0.8 μm inside from both ends of the gate electrode 3. (Corresponding to the third step in FIG. 2-2).

  Next, in the source electrode and drain electrode forming step, Cr films 5a, 6a, 9a having good adhesion with Au are formed by electron beam evaporation to a thickness of about 10 nm, and further on the Cr films 5a, 6a, 9a. Then, an Au film 5b, 6b, 9b is formed to a thickness of about 50 nm by resistance heating vacuum deposition (FIG. 2-3). Next, this TFT 1a is immersed in acetone at room temperature, thereby forming Cr film formed on the photoresist pattern 8a. The photoresist pattern 8a is lifted off together with the film 9a and the Au film 9b to form Cr films 5a and 6a and Au films 5b and 6b based on the photoresist pattern 8a.

  Since the width of the photoresist pattern 8a in the horizontal direction of the paper surface is narrower than the width of the gate electrode 3 due to the wrapping of the irradiated ultraviolet rays U, the tips of the source electrode 5 and the drain electrode 6 are respectively connected to the gate electrode. 3 is overlapped, but the length of the overlap in the horizontal direction of the paper is as small as D = about 0.8 μm (see FIG. 1), so the parasitic capacitance formed at the overlapping position is extremely small, and the device performance of TFT1 Has little effect. Further, the photoresist film is patterned on the Cr films 5a and 6a and the Au films 5b and 6b, the Au films 5b and 6b are etched with aqua regia, and the Cr films 5a and 6a are mixed with ammonium nitrate, an aqueous solution of perchloric acid and water. Etching with the mixed solution forms the source electrode 5 and the drain electrode 6 in a desired pattern (corresponding to the fourth step in FIG. 2-4).

Next, in the first cleaning step, organic contaminants such as carbon at the location where the organic semiconductor layer 7 is formed are removed by, for example, acid boiling, an ultraviolet ozone cleaner, oxygen plasma treatment, or the like. Next, heavy metals, alkali metals, and the like that cause mobile ions at the location where the organic semiconductor layer 7 is formed in the second cleaning step are obtained by, for example, acid cleaning having an appropriate purity or hot water cleaning at 90 ° C. or higher. Remove.
Next, in the organic semiconductor forming step, the glass substrate 2 is kept on the insulating film 4 exposed between the source electrode 5 and the drain electrode 6 by the resistance heating vacuum deposition method while keeping the temperature at 70 ° C. After pentacene is deposited to a thickness of about 100 nm over the entire surface of the drain electrode 6 and the like, the pentacene is patterned by lithography to form an organic semiconductor layer 7 between and near the source electrode 5 and the drain electrode 6. 1 is completed (corresponding to the fifth step).

Next, performance evaluation of the TFT 1 manufactured by the above manufacturing method will be described with reference to FIG.
FIG. 3 shows the drain current-source-drain voltage characteristics of the TFT 1. The field effect mobility calculated from the linear region shown in the graph of FIG. 3 is 0.12 cm ² / Vs, and the threshold voltage is −1V. A gate capacitance-voltage characteristic in which a bias was applied to the gate electrode 3 with the source electrode 5 and the drain electrode 6 grounded to ground was measured. As a result, the gate capacitance Cg when 1.5 V was applied to the gate electrode 3 was 1.55 pF. The mutual conductance g obtained from the saturation region in FIG. 3 was 1.8 μS. The high-frequency cutoff frequency f _T obtained based on the gate capacitance Cg and the mutual conductance g was calculated as f _T = 0.18 MHz from “f _T = g m / 2πCg”. Therefore, TFT1 is very excellent in operation in a high frequency range.

Next, the operation and effect of the manufacturing method of the organic thin film field effect transistor described above will be described.
According to the method for manufacturing an organic thin film field effect transistor described above, a channel region is formed by a photoresist pattern 8a formed by back exposure using the gate electrode 3 as a mask pattern, and then a source is formed based on the photoresist pattern 8a. Since the end portions of the electrode 5 and the drain electrode 6 are formed, the relative positions of the source electrode 5 and the drain electrode 6 with respect to the gate electrode can be accurately and easily positioned, and are formed between the electrodes 3, 5, 6. The generation of parasitic resistance and parasitic capacitance can be greatly reduced, and high performance of the TFT 1 can be realized.

Since the light that has passed through the side of the gate electrode 3 does not travel above the gate electrode 3 by performing the back exposure with the ultraviolet rays U, the overlap between the gate electrode 3 and the source electrode 5 and the gate electrode 3 and the drain electrode 6 is overlapped. The parasitic capacitance can be reduced by suppressing the capacitance to 0.8 μm or less.
Since the electrodes 5 and 6 and the organic semiconductor layer 7 are directly formed on the insulating film 4, the step of forming the inorganic semiconductor base for forming the inorganic semiconductor, such as the step of the inorganic semiconductor TFT, can be omitted. The process can be simplified. Since there is nothing other than the gate electrode 3 to block the irradiated ultraviolet ray U, the irradiation time of the ultraviolet ray U can be shortened.

In the first cleaning step, organic contaminants at the locations where the organic semiconductor layer 7 is formed are removed, so that organic contaminants can be prevented from entering the deposited organic semiconductor layer 7, and the device performance of the TFT 1 can be prevented. Can be improved.
In the second cleaning step, since heavy metals and alkali metals are removed where the organic semiconductor layer 7 is formed, generation of mobile ions in the deposited organic semiconductor layer 7 can be greatly reduced. The element performance of the TFT 1 can be improved.

Next, an example in which the invention of claim 3 is applied to a method of manufacturing a stagger type organic thin film field effect transistor will be described. In addition, about the structure similar to Example 1, "A" is attached to the same code | symbol and description is abbreviate | omitted.
First, the configuration of the staggered TFT 1A will be described with reference to FIG. The TFT 1A is formed on the organic semiconductor layer 7A and the source electrode 5A and the drain electrode 6A patterned on the glass substrate 2A, the organic semiconductor layer 7A that is formed between the source electrode 5A and the drain electrode 6A, and constitutes a channel. 4A, and a gate electrode 3A formed on the insulating film 4A corresponding to a portion above the portion where the source electrode 5A and the drain electrode 6A are not formed.

Next, a manufacturing method of the TFT 1A will be described with reference to FIG.
First, the source electrode 5A and the drain electrode 6A are patterned on the surface of the glass substrate 2A by photolithography (corresponding to the first step). Next, the organic semiconductor layer 7A is formed by patterning on the surface of the glass substrate 2A between the source electrode 5A and the drain electrode 6A and in the vicinity thereof (corresponding to the second step). Next, an insulating film 4A is formed on the organic semiconductor layer 7A (corresponding to the third step).

  Next, a positive photoresist film 8A is formed over the entire surface of the insulating film 4A and the exposed source electrode 5A and drain electrode 6A. Next, parallel light of ultraviolet rays U is irradiated from the back surface of the glass substrate 2A. Since the ultraviolet rays U are irradiated from the back surface of the glass substrate 2A, the pattern of the source electrode 5A and the drain electrode 6A becomes a mask pattern, and the pattern of the source electrode 5A and the drain electrode 6A is transferred to the photoresist film 8A (FIG. 4). 1). Next, the photoresist film 8A is developed to form a photoresist pattern 8b having almost the same pattern as that of the source electrode 5A and the drain electrode 6A (FIG. 4-2) (corresponding to the fourth step).

  Next, the metal layer 3a constituting the gate electrode 3A is formed over the entire surface of the photoresist pattern 8b and the exposed insulating film 4A (FIG. 4-3). Next, the remaining photoresist pattern 8b is lifted off together with the metal layer 3a formed on the upper surface thereof. Finally, the metal layer 3a is patterned to form the gate electrode 3A (corresponding to the fifth step), thereby completing the TFT 1A (FIG. 4-4).

  Thus, since the gate electrode 3A is formed based on the photoresist pattern 8b formed using the source electrode 5A and the drain electrode 6A as a mask pattern, the relative positions of the gate electrode 3A, the source electrode 5A, and the drain electrode 6A are determined. Accurate and easy positioning can greatly reduce the occurrence of parasitic resistance and capacitance. Since the organic semiconductor layer 7A is formed directly on the glass substrate 2A, simplification of the process can be realized.

Next, a modified example in which a part of the present invention is partially modified will be described.
1) In the above-described embodiments, the organic semiconductor layers 7 and 7A are made of pentacene. However, the organic semiconductor layers 7 and 7A may be made of an organic semiconductor such as anthracene and tetracene, and are not limited to a specific organic semiconductor. A large degree is desirable.
2) In the above embodiment, the glass substrates 2 and 2A are applied to the substrate. However, the material of the substrate is not limited as long as it can transmit at least the ultraviolet ray U and has an insulating property. Not what you want. By configuring the channel with the organic semiconductor layers 7 and 7A, the entire process can proceed at a low temperature. Therefore, flexible and non-flexible synthetic resins having poor heat resistance can be applied. A flexible display can also be realized by applying an organic TFT formed on a flexible substrate to an organic EL display or the like. Even when a flexible display is configured in this way, the relative positions between the electrodes are accurately positioned, so that no malfunction occurs even if the display is deformed.

3) The metal material composing each electrode is not limited to the metal material of the above-mentioned embodiment, and the gate electrode, the source electrode, and the drain electrode are Ta, Cr, Al, Ti, Ni, Cu, Mo, Pd, Ag , In, Sn, Er, W, Pt, and Au. In particular, the source electrode and the drain electrode may have a two-layer structure of any two kinds of metals. When the gate electrode is made of Ta or Al, it is desirable to perform anodic oxidation. The gate electrode may be made of a conductive polymer.

4) The insulating material constituting the insulating film is not limited to the insulating material of the above-described embodiment, but the insulating film is made of SiO ₂ , SiN, Al ₂ O ₃ , Ta ₂ O ₅ , SiON, P ₂ O _5, etc. It may be composed of an inorganic material or an organic material such as polyparaxylylene, parylene, or polyvinylphenol.
5) GeO _X on top of each TFT1,1A the foregoing Examples, SiO _X, the organic insulating film, polyparaxylylene, parylene, may be formed a protective layer which is constituted by a polyvinyl phenol.

  In addition, the manufacturing method of the organic thin film field effect transistor of this invention is not limited only to the above-mentioned Example, Of course, various changes can be added within the range which does not deviate from the summary of this invention.

1 is an organic thin film field effect transistor manufactured by a manufacturing method according to an embodiment of the present invention. It is a figure of the ultraviolet irradiation process of a TFT manufacturing process. It is a figure of the photoresist pattern formation process of a TFT manufacturing process. It is a figure of the metal film formation process of a TFT manufacturing process. It is a figure of the source electrode and drain electrode formation process of a TFT manufacturing process. It is a graph of the drain current-source-drain voltage characteristic of TFT. It is a figure of the source electrode and drain electrode formation process of a stagger type TFT manufacturing process. It is a figure of the photoresist pattern formation process of a stagger type TFT manufacturing process. It is a figure of a stagger type TFT manufacturing process metal layer formation process. It is a figure of a stagger type TFT manufacturing process gate electrode formation process.

Explanation of symbols

1, 1A Organic thin film field effect transistor 2, 2A Glass substrate 3, 3A Gate electrode 4, 4A Insulating film 5, 5A Source electrode 6, 6A Drain electrode 7, 7A Organic semiconductor layer 8, 8A Photoresist film 8a, 8b Photo Resist pattern

Claims (17)

In a method for manufacturing an organic thin film field effect transistor comprising a first electrode, a second electrode, and an organic semiconductor layer constituting a channel, and formed on a transparent substrate,
In order to form the second electrode, a photoresist pattern is formed by irradiating light from the back surface of the substrate using the pattern of the first electrode as a mask pattern. . A first step of patterning a gate electrode on a substrate surface capable of transmitting light;
A second step of forming an insulating film on the gate electrode;
Forming a photoresist film on the insulating film, using the gate electrode pattern as a mask pattern, and irradiating the photoresist film with light from the back of the substrate to form a photoresist pattern;
A fourth step of forming a source electrode and a drain electrode based on the photoresist pattern;
A fifth step of forming an organic semiconductor layer between the source electrode and the drain electrode;
A method for producing an organic thin film field effect transistor, comprising: A first step of patterning a source electrode and a drain electrode on a substrate surface capable of transmitting light;
A second step of forming an organic semiconductor layer between the source electrode and the drain electrode;
A third step of forming an insulating film on the organic semiconductor layer;
A fourth step of forming a photoresist film on the insulating film, using the pattern of the source electrode and the drain electrode as a mask pattern, and irradiating the photoresist film with light from the back of the substrate to form a photoresist pattern;
A fifth step of forming a gate electrode based on the photoresist pattern;
A method for producing an organic thin film field effect transistor, comprising:   4. The method of manufacturing an organic thin film field effect transistor according to claim 2, wherein the light irradiated from the back surface is ultraviolet light.   5. The organic material according to claim 2, further comprising a first cleaning step of cleaning organic contaminants at a location where the organic semiconductor layer is formed before the organic semiconductor layer is formed. A method of manufacturing a thin film field effect transistor.   6. The method according to claim 2, further comprising a second cleaning step of cleaning heavy metal and alkali metal at a place where the organic semiconductor layer is formed before the organic semiconductor layer is formed. Manufacturing method of organic thin film field effect transistor.   The method of manufacturing an organic thin film field effect transistor according to claim 2, wherein the organic semiconductor layer is made of pentacene.   Each of the gate electrode, source electrode, and drain electrode is made of any of Ta, Cr, Al, Ti, Ni, Cu, Mo, Pd, Ag, In, Sn, Er, W, Pt, and Au. A method for producing an organic thin film field effect transistor according to any one of claims 2 to 7.   Each of the source electrode and drain electrode has a two-layer structure made of any two kinds of metals among Ta, Cr, Al, Ti, Ni, Cu, Mo, Pd, Ag, In, Sn, Er, W, Pt, and Au. 8. The method for producing an organic thin film field effect transistor according to claim 2, wherein the method is provided.   8. The method of manufacturing an organic thin film field effect transistor according to claim 2, wherein the gate electrode is made of Ta or Al and anodized before forming the insulating film.   8. The method for producing an organic thin film field effect transistor according to claim 2, wherein the gate electrode is made of a conductive polymer.   The method of manufacturing an organic thin film field effect transistor according to claim 2, wherein the insulating film is made of an inorganic material. 13. The organic thin film field effect transistor according to claim 12, wherein the insulating film is composed of any one of SiO ₂ , SiN, Al ₂ O ₃ , Ta ₂ O ₅ , SiON, and P ₂ O _5. Manufacturing method.   12. The method of manufacturing an organic thin film field effect transistor according to claim 2, wherein the insulating film is made of an organic material.   15. The method of manufacturing an organic thin film field effect transistor according to claim 14, wherein the insulating film is made of any one of polyparaxylylene, parylene, and polyvinylphenol.   16. The method of manufacturing an organic thin film field effect transistor according to claim 2, wherein a protective layer is formed on the uppermost surface of the organic thin film field effect transistor. GeO _X the protective layer, SiO _X, the organic insulating film, polyparaxylylene, parylene, organic thin-film field effect transistor according to claim 16, characterized in that it is constituted by one of polyvinylphenol Production method.

Images