JP2011049221A - Organic thin film transistor and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic thin film transistor capable of suppressing characteristic deterioration in the atmosphere and also characteristic deterioration by reducing damage on an organic semiconductor layer by membrane stress. <P>SOLUTION: The organic thin film transistor includes a gate electrode, a gate insulating film, a source electrode, a drain electrode, an organic semiconductor layer and a sealing layer, which are formed on a substrate. The organic semiconductor layer has a channel section sandwiched between the source electrode and the drain electrode, and the sealing layer is composed of at least a first sealing layer divided by the channel section and covering the organic semiconductor layer, a second sealing layer covering the organic semiconductor layer including the channel section, and an optional third sealing layer covering the second sealing layer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an organic thin film transistor in which an organic material is used for a semiconductor portion.

  In recent years, so-called organic thin film transistors using a semiconductor made of an organic material have attracted attention with respect to inorganic semiconductors represented by silicon.

  Since an organic thin film transistor can produce an element at a low process temperature of 200 ° C. or lower, it is possible to form a transistor element on a plastic substrate having low heat resistance, and thus the flexibility of the plastic substrate It is being studied as a technology to realize a flexible device that takes advantage of.

  In addition, since an organic material can be manufactured by a printing method or the like depending on the type of the material, it is also expected as a semiconductor element capable of reducing a manufacturing cost and manufacturing a large area device by printing.

On the other hand, organic semiconductor materials are generally susceptible to deterioration under the influence of oxygen and moisture in the atmosphere. Therefore, the characteristics of the organic thin film transistor may be deteriorated by exposure to the atmosphere.
Therefore, it is important to suppress deterioration of characteristics in order to put an organic thin film transistor into practical use. An example of the characteristic here is carrier mobility.

  In order to solve the characteristic deterioration due to oxygen and moisture in the atmosphere, for example, in Patent Document 1, a sealing layer made of a resin is formed on the organic transistor to improve the barrier property against oxygen and moisture of the organic transistor, thereby improving stability. A method for improving the above is disclosed.

  Patent Document 2 discloses a method for suppressing deterioration of an organic semiconductor layer by inserting a protective layer between the organic semiconductor layer and a sealing layer made of a resin.

  In these methods, a technique for providing an organic transistor in which deterioration of characteristics is suppressed by providing a sealing layer or a protective layer to suppress deterioration of characteristics due to oxygen or moisture is disclosed.

JP 2003-338629 A JP 2006-156985 A

However, the methods disclosed in Patent Document 1 and Patent Document 2 have the following problems.
That is, when forming a protective layer or a sealing layer for protecting the organic semiconductor layer, it is necessary to cure the resin material that becomes the sealing layer. There has been a problem that the characteristics of the organic semiconductor layer deteriorate due to the stress generated during the curing of the resin material damaging the organic semiconductor layer.

  Therefore, the present invention suppresses the characteristic deterioration of the organic transistor in the atmosphere, reduces the damage caused by the film stress on the organic semiconductor layer, and suppresses the characteristic deterioration due to the stress generated when the resin material is cured. It is an object to provide a thin film transistor and a manufacturing method thereof.

  As a result of intensive studies to solve the above problems, the present inventors have found that the organic thin film transistor having a structure in which at least the sealing layer covering the organic semiconductor layer is divided at the channel portion can suppress the deterioration of characteristics. The headline and the present invention have been completed.

However, according to the present invention, the substrate has a gate electrode, a gate insulating film, a source electrode and a drain electrode, an organic semiconductor layer, and a sealing layer.
The organic semiconductor layer has a channel portion sandwiched between the source electrode and the drain electrode,
A first sealing layer that is divided by at least the channel portion and covers the organic semiconductor layer;
A second sealing layer including a channel portion and covering the organic semiconductor layer;
An organic thin film transistor is provided that includes an optional third sealing layer covering the second sealing layer.

According to the invention, there is provided a transistor in which the first sealing layer is divided in the channel length direction.
According to the invention, there is provided a transistor in which the first sealing layer is divided in the channel width direction.

According to the invention, there is provided a transistor in which the second sealing layer includes the channel portion and the source / drain electrodes, covers at least part of the first sealing layer and covers the organic semiconductor layer. Provided.
Further, according to the present invention, there is provided a transistor in which the third sealing layer covers at least the channel portion via the second sealing layer or the first sealing layer and the second sealing layer. Is done.

In addition, according to the present invention, there is provided a transistor in which the third sealing layer covers the organic semiconductor layer via the first sealing layer and the second sealing layer.
In addition, according to the present invention, there is provided a transistor in which the first sealing layer is formed of an organic insulating material, a metal, or a metal alloy.
In addition, according to the present invention, there is provided a transistor in which the third sealing layer is formed of an organic insulating material, a metal, or a metal alloy.

  Also, according to the present invention, the first and third sealing layers are independently selected from organic insulating materials consisting of parylene, polyimide, polyvinyl alcohol and polyvinylphenol, or gold, silver, A transistor is provided that is formed of a material selected from metals consisting of copper and aluminum or alloys of these metals.

Furthermore, according to the present invention, a step of forming a gate electrode on a substrate, a step of manufacturing a gate insulating film, a step of forming a source electrode and a drain electrode, a step of forming an organic semiconductor layer, Forming a sealing layer covering the organic semiconductor layer,
In the step of forming the sealing layer, the first sealing layer is formed so as to cover the organic semiconductor layer by dividing at least a channel portion sandwiched between the source electrode and the drain electrode of the organic semiconductor layer. Process,
Forming a second sealing layer so as to cover the organic semiconductor layer, including the channel portion;
Forming an optional third sealing layer covering the second sealing layer. A method for manufacturing a transistor is provided.

According to the present invention, the step of forming the sealing layer includes
Forming the first sealing layer;
Forming the second sealing layer;
A transistor manufacturing method including a step of forming a third sealing layer by forming a material for forming a third sealing layer so as to cover the channel portion via the second sealing layer. Provided.
According to the present invention, the step of forming the first sealing layer includes
A method for manufacturing a transistor, which is a step of forming a first sealing layer using a metal or a metal alloy, is provided.

  Furthermore, according to the present invention, there is provided a method for manufacturing a transistor, wherein the step of forming the third sealing layer is a step of forming the third sealing layer from a metal or a metal alloy material.

In the organic thin film transistor according to the present invention, the first sealing layer is separated into two portions at least in the channel length direction of the channel portion. By dividing the first sealing layer, the film stress generated when the resin material is cured is relaxed, the stress applied to the organic semiconductor layer is reduced, and the damage to the organic semiconductor layer is reduced. The
Furthermore, since the first sealing layer is divided into two or more in the channel width direction of the channel portion, the first sealing layer film stress is further relaxed, and the stress applied to the organic semiconductor layer is further reduced. Thus, the effect of further reducing damage to the organic semiconductor layer is increased.

The organic semiconductor layer excluding the channel portion is sealed by the first sealing layer, and is protected by the second sealing layer that includes the channel portion and covers the organic semiconductor layer directly or via the first sealing layer. Therefore, damage to the organic semiconductor layer due to oxygen and moisture can be suppressed.
Further, since the second sealing layer and the organic semiconductor layer are in contact with each other only at the channel portion, damage to the organic semiconductor layer due to the film stress of the second sealing layer is also reduced.
Therefore, while the influence of oxygen and moisture on the organic transistor due to the first and second sealing layers is prevented, the damage caused by the film stress on the organic semiconductor layer is reduced, and the deterioration of the characteristics of the organic thin film transistor is suppressed. Is possible.

  Furthermore, in the organic thin film transistor of the present invention, the second sealing layer includes a channel portion and covers the organic transistor, so that at least the organic semiconductor layer is covered by the first and second sealing layers. In addition, the penetration of oxygen and moisture can be suppressed, and at the same time, the entire organic transistor is covered with the second sealing layer, so that the characteristic deterioration in the atmosphere can be further suppressed.

Furthermore, in the organic thin film transistor of the present invention, an organic semiconductor thin film is provided on the second sealing layer by having a third sealing layer that covers the channel portion of the organic semiconductor layer via the second sealing layer. Since the channel portion of the semiconductor layer is covered with the second and third sealing layers, the penetration of oxygen and moisture into the organic semiconductor layer is further suppressed, and the deterioration of characteristics in the atmosphere is further suppressed.
Note that the third sealing layer is formed to be larger than the channel portion in order to further suppress the permeation of oxygen and moisture from the surroundings into the channel portion, whereby the above effect is further increased.

  Furthermore, in the organic thin film transistor of the present invention, since the third sealing layer covers the organic transistor, at least the organic semiconductor layer is covered with the first, second, and third sealing layers. In addition, the penetration of moisture and moisture can be further suppressed, and at the same time, the entire organic transistor is covered with the third sealing layer, whereby the deterioration of characteristics in the atmosphere can be further suppressed.

  By using the first sealing layer separated through the channel portion as a metal, it becomes possible to function as a source electrode and a drain electrode in contact with the organic semiconductor in addition to the function as the sealing layer. As a result, the contact resistance with the organic semiconductor layer is reduced and the characteristics of the organic thin film transistor can be improved.

  Furthermore, in the organic thin film transistor of the present invention, the third sealing layer is made of a metal or a metal alloy, so that the third sealing layer is interposed via the second sealing layer in addition to the function as the sealing layer. It becomes possible to function as a gate electrode capable of applying an electric field to a channel portion existing underneath, and as a second gate electrode, a double gate type organic thin film transistor capable of applying a gate voltage to the channel portion is obtained. The amount of current that can be increased can be increased.

  In addition, according to the method of manufacturing an organic thin film transistor according to the present invention, the step of forming the sealing layer on the organic semiconductor layer is a portion where the organic semiconductor layer is sandwiched between the source electrode and the drain electrode of the organic semiconductor layer. Forming a first sealing layer by forming a material for forming the first sealing layer so as to be divided and covered by the channel portion, and the organic semiconductor layer including the channel portion Including a step of forming a second sealing layer by forming a material for forming the second sealing layer so as to cover the substrate, thereby making it possible to manufacture an organic thin film transistor with suppressed characteristic deterioration. .

  Furthermore, in the method of manufacturing an organic thin film transistor according to the present invention, a material for forming the third sealing layer is formed so that the step of forming the sealing layer covers the channel portion via the second sealing layer. By including the step of forming the third sealing layer, it is possible to manufacture an organic thin film transistor in which the deterioration of characteristics in the atmosphere is further suppressed.

  Furthermore, in the method for producing an organic thin film transistor of the present invention, the step of forming the first sealing layer uses a metal or an alloy, so that it is possible to produce an organic thin film transistor with improved characteristics while suppressing deterioration in characteristics. It becomes.

  Furthermore, in the method for manufacturing an organic thin film transistor of the present invention, the step of forming the third sealing layer uses a metal or an alloy, thereby suppressing characteristic deterioration and increasing the amount of current obtained. Type organic thin film transistor can be produced.

  Further, for example, as shown in FIG. 10, an organic thin film transistor in which the first sealing layer 7 is divided in the channel width direction can be given. By further dividing and forming the first sealing layer 7, it is possible to further reduce the stress applied to the organic semiconductor layer 6.

The principal part structure of the organic thin-film transistor which concerns on embodiment of this invention is shown, (a) is a top view, (b) is A-A 'arrow sectional drawing in (a). (C) is sectional drawing of the organic thin-film transistor covered with the 2nd sealing layer 8, (d) is the sealing layer 10, the 1st sealing layer 7, and the 2nd sealing layer 8 FIG. 6 is a cross-sectional view of an organic thin film transistor when a third sealing layer 9 is included. (E) is sectional drawing of an organic thin-film transistor in case the sealing layer 10 contains the 1st sealing layer 7, the 2nd sealing layer 8, and the 3rd sealing layer 9, f) is a cross-sectional view of an organic thin film transistor covered entirely with a third sealing layer 9. (A)-(d) is sectional drawing of the process process of the manufacturing method of the organic thin-film transistor in FIG. (E)-(g) is sectional drawing of the process process of the manufacturing method of the organic thin-film transistor in FIG. The principal part structure of the organic thin-film transistor which concerns on Example 1 of this invention is shown, (a) is a top view, (b) is B-B 'arrow sectional drawing in (a). (A)-(d) is sectional drawing of the process process of the manufacturing method of the organic thin-film transistor in FIG. (E) And (f) is sectional drawing of the process process of the manufacturing method of the organic thin-film transistor in FIG. It is sectional drawing which shows the principal part structure of the organic thin-film transistor which concerns on the comparative example 1 of this invention. The principal part structure of the organic thin-film transistor which concerns on Example 4 of this invention is shown, (a) is a top view, (b) is C-C 'arrow sectional drawing in (a). It is sectional drawing which shows the principal part structure of the organic thin-film transistor which concerns on Example 5 of this invention. It is sectional drawing which shows the principal part structure of the organic thin-film transistor which concerns on Example 6 of this invention. The principal part structure of the organic thin-film transistor which concerns on Example 7 of this invention is shown, a) is a top view, (b) is D-D 'arrow sectional drawing in (a). The principal part structure of the organic thin-film transistor which concerns on Example 8 of this invention is shown, (a) is a top view, (b) is E-E 'arrow sectional drawing in (a). (A)-(c) is sectional drawing which shows an example of the organic thin-film transistor which concerns on embodiment of this invention, (a) is a top view, (b) is a FF 'line arrow view in (a). It is sectional drawing. (D)-(f) is sectional drawing which shows an example of the organic thin-film transistor which concerns on embodiment of this invention. (G)-(i) is sectional drawing which shows an example of the organic thin-film transistor which concerns on embodiment of this invention. (J) is sectional drawing which shows an example of the organic thin-film transistor which concerns on embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
(1) Organic thin-film transistor FIG. 1: shows the principal part structure of the organic thin-film transistor 100 of this embodiment, (a) is a top view, (b) is an AA 'arrow sectional drawing in (a). is there.

As shown in FIGS. 1A and 1B, the organic thin film transistor 100 of the present invention has
A gate electrode 2 and a gate insulating film 3 are formed on the substrate 1, and a source electrode 4 and a drain electrode 5 are separately formed on the gate insulating film 3. The organic semiconductor layer 6 is formed on the gate insulating film 3, the source electrode 4, and the drain electrode 5 so as to fill a gap between the source electrode 4 and the drain electrode 5, and is sandwiched between the source electrode 4 and the drain electrode 5. A channel portion 20 is provided in the region of the organic semiconductor layer. A sealing layer 10 is formed on the organic semiconductor layer 6. The organic semiconductor layer includes the first sealing layer 7 that is divided by the channel portion 20 and covers the organic semiconductor layer, and covers the organic semiconductor layer. A sealing layer 10 is constituted by the second sealing layer 8.

The basic configuration of the organic thin film transistor 100 of the present invention is as described above. For example, as shown in FIG. 1C, the second sealing layer 8 may include the channel portion 20 and cover the organic transistor.
Furthermore, as shown in FIGS. 1D and 1E, the sealing layer 10 in the organic thin film transistor 100 of the present invention includes a first sealing layer 7, a second sealing layer 8, and a third sealing layer. The sealing layer 9 may be included. The third sealing layer 9 is a sealing layer that covers the channel portion via the second sealing layer 8.
Furthermore, as shown in FIG. 1F, the third sealing layer 9 may cover the organic transistor.

Substrate The substrate 1 is not particularly limited, and for example, a glass substrate, a quartz substrate, a resin substrate, or the like can be used.

Gate electrode The material which comprises the gate electrode 2 will not be specifically limited if it is an electroconductive material. For example, the gate electrode 2 includes gold (Au), platinum (Pt), silver (Ag), copper (Cu), palladium (Pd), rubidium (Rb), rhodium (Rh), aluminum (Al), titanium (Ti) ), Molybdenum (Mo), tantalum (Ta), silicon (Si), or an alloy thereof.

Gate insulating film The material which comprises the gate insulating film 3 will not be specifically limited if it has insulation. For example, the gate insulating film 3 may be an inorganic insulating film made of an inorganic material such as silicon oxide (SiO _x ), aluminum oxide (AlO _x ), or tantalum oxide (TaO _x ), and parylene, polyimide, polyvinyl alcohol, etc. Alternatively, an organic insulating film made of an organic material such as polyvinylphenol may be used.

Source / Drain Electrode The material constituting the source electrode 4 and the drain electrode 5 is not particularly limited as long as it is a conductive material, but is preferably composed of a material having low electrical resistance. For example, the source electrode 4 and the drain electrode 5 are made of gold (Au), silver (Ag), copper (Cu), platinum (Pt), palladium (Pd), rubidium (Rb), rhodium (Rh), aluminum (Al). , Titanium (Ti), molybdenum (Mo), tantalum (Ta), silicon (Si), or an alloy thereof can be used.

  The source electrode 4 and the drain electrode 5 may be made of the same material or different materials. However, it is more preferable that they are made of the same material because the source electrode 4 and the drain electrode 5 can be formed in one step.

Organic Semiconductor Layer The organic semiconductor layer 6 is a layer containing an organic material as a main component. The material which comprises the organic-semiconductor layer 6 will not be specifically limited if it is an organic semiconductor used for a conventionally well-known organic thin-film transistor. For example, the organic semiconductor layer 6 can be made of an organic semiconductor material such as fullerene, a fullerene derivative, pentacene, a pentacene derivative, a perylene derivative, phthalocyanine, oligothiophene, or polythiophene.

Sealing layer The first sealing layer 7 is separated into two parts by a channel part, and the two parts may be made of the same material or different materials. However, it is more preferable that the first sealing layer 7 is formed from the same material because the first sealing layer 7 can be formed in one step. Moreover, the thing with the high barrier property with respect to oxygen and a water | moisture content is preferable.

As a material constituting the first sealing layer 7, an organic insulating material, an inorganic insulating material, a metal and a metal alloy material, or the like is used. However, the material is not particularly limited thereto. For example, examples of the organic insulating material include parylene, polyimide, polyvinyl alcohol, and polyvinylphenol; examples of the inorganic insulating material include silicon oxide (SiO _x ), silicon nitride (SiN _x ), aluminum oxide (AlO _x ), and tantalum oxide ( TaO _x ) and the like; Examples of metal and metal alloy materials include gold (Au), silver (Ag), copper (Cu), platinum (Pt), palladium (Pd), rubidium (Rb), and rhodium (Rh). , Aluminum (Al), titanium (Ti), molybdenum (Mo), tantalum (Ta) and silicon (Si), or alloys thereof; various materials can be used.

The material which comprises the 2nd sealing layer 8 will not be specifically limited if it has insulation. For example, the second sealing layer 8 may be an inorganic insulating film made of an inorganic material such as silicon oxide (SiO _x ), aluminum oxide (AlO _x ), or tantalum oxide (TaO _x ), or parylene or polyimide. An organic insulating film made of an organic material such as polyvinyl alcohol or polyvinyl phenol may be used. Further, as the sealing material, a material having a high barrier property against oxygen and moisture is preferable.

Furthermore, a third sealing layer 9 can be formed.
As a material constituting the third sealing layer 9, an organic insulating material, an inorganic insulating material, a metal and a metal alloy material, or the like is used. However, the material is not particularly limited thereto. For example, examples of the organic insulating material include parylene, polyimide, polyvinyl alcohol, and polyvinylphenol, and examples of the inorganic insulating material include silicon oxide (SiO _x ), silicon nitride (SiN _x ), aluminum oxide (AlO _x ), and tantalum oxide ( TaO _x ) is a metal and metal alloy material such as gold (Au), silver (Ag), copper (Cu), platinum (Pt), palladium (Pd), rubidium (Rb), rhodium (Rh), aluminum (Al), titanium (Ti), molybdenum (Mo), tantalum (Ta), silicon (Si), or alloys thereof.

  As described above, the organic thin film transistor 100 includes the first sealing layer 7 and the sealing layer 10 including the second sealing layer 8, and the first sealing layer 7 is the channel portion 20. The organic semiconductor layer 6 is divided so that the second sealing layer 8 includes the channel portion 20 and covers the organic semiconductor layer 6. Thereby, there exists an effect that the characteristic deterioration of an organic thin-film transistor is suppressed.

  The organic thin film transistor having the structure shown in FIG. 1 has been described above. However, the structure shown here is an example of the embodiment of the present invention, and the present invention is not limited to this. Another example of the organic thin film transistor of the present invention is, for example, an organic thin film transistor in which a gate electrode is patterned as shown in FIG.

  Further, for example, as shown in FIG. 10, an organic thin film transistor in which the first sealing layer 7 is divided in the channel width direction can be given. By further dividing and forming the first sealing layer 7, it is possible to further reduce the stress applied to the organic semiconductor layer 6.

  In addition, for example, as shown in FIGS. 11A and 11B, the second semiconductor layer that covers the organic semiconductor layer including the channel portion 20 and is formed in several portions on the first sealing layer 7 is formed. An organic thin film transistor provided with the sealing layer 8 is exemplified. In this way, by forming the second sealing layer 8 in a further divided manner, the stress applied to the organic semiconductor layer 6 by the second sealing layer 7 can be further reduced.

  In addition, for example, as shown in FIG. 11C, the second sealing layer 8 that covers the organic semiconductor layer 6 including the channel portion 20 and is formed on the first sealing layer 7 in several locations. And an organic thin film transistor provided with a third sealing layer 9 covering the channel portion 20 via the second sealing layer.

  Further, for example, as shown in FIG. 11 (d), a second sealing layer 8 covering the organic semiconductor layer 6 including the channel portion 20, the source electrode 4, the drain electrode 5, and the first sealing layer 7; The organic thin-film transistor provided with the 3rd sealing layer 9 which covers the 2nd sealing layer 8 whole is mentioned. By covering the element with the third sealing layer 9 in this way, the organic semiconductor layer 6 is protected by the plurality of sealing layers, so that deterioration of characteristics due to oxygen and moisture can be further suppressed. It becomes.

  Further, as shown in FIGS. 11E and 11F, a top contact type organic thin film transistor in which the source electrode 4 and the drain electrode 5 are formed on the organic semiconductor layer 6 may be used. By adopting the top contact structure, the organic semiconductor layer 6 has a structure in which the peripheral portion is protected by the source electrode 4 and the drain electrode 5 and the first sealing layer 7, and the channel portion 20 is protected by the second sealing layer 8. Become.

  Further, for example, as shown in FIG. 11G, a second sealing layer 8 that covers the organic semiconductor layer 6 including the channel portion 20, the source electrode 4, the drain electrode 5, and the first sealing layer 7 is provided. The top contact type organic thin-film transistor provided is mentioned.

  Further, for example, as shown in FIG. 11 (h), a second sealing layer 8 covering the organic semiconductor layer 6 including the channel portion 20, the source electrode 4, the drain electrode 5, and the first sealing layer 7; And a top contact type organic thin film transistor provided with a third sealing layer 9 covering the channel portion via the second sealing layer.

  For example, as shown in FIG. 11 (i), a second sealing layer 8 covering the organic semiconductor layer 6 including the channel portion 20, the source electrode 4, the drain electrode 5, and the first sealing layer 7; A top contact type organic thin film transistor provided with a third sealing layer 9 covering the second sealing layer 8 is exemplified.

  For example, as shown in FIG. 11 (j), a second sealing layer 8 covering the organic semiconductor layer 6 including the channel portion 20, the source electrode 4, the drain electrode 5, and the first sealing layer 7; A top contact type organic thin film transistor provided with a third sealing layer 9 covering the entire second sealing layer 8 may be mentioned.

(2) Manufacturing method of organic thin-film transistor Hereinafter, the manufacturing method of the organic thin-film transistor 100 of this embodiment is demonstrated. FIG. 2 is a cross-sectional view showing process steps in the method of manufacturing the organic thin film transistor 100 of FIG. In addition, the manufacturing method demonstrated below is an example, Comprising: It is not limited to this manufacturing method.

  The method of manufacturing the organic thin film transistor 100 includes a gate electrode forming step for forming the gate electrode 2 on the substrate 1, a gate insulating film forming step for forming the gate insulating film 3 on the gate electrode 2, and a source on the gate insulating film 3. A source / drain electrode forming step in which the electrode 4 and the drain electrode 5 are formed at a distance from each other, and an organic semiconductor in which the organic semiconductor layer 6 is formed on the gate insulating film 3 so as to be sandwiched between the source electrode 4 and the drain electrode 5 A sealing layer forming step of forming a sealing layer 10 and a sealing layer forming step, wherein the sealing layer forming step forms a first sealing layer 7 that covers and divides the organic semiconductor layer at the channel portion. A sealing layer forming step, and a second sealing layer forming step of forming a second sealing layer 8 covering the organic semiconductor layer including the channel portion.

  Although the basic steps of the method for manufacturing the organic thin film transistor 100 of the present invention are as described above, the step of forming the sealing layer 10 further includes the third sealing that covers the channel portion via the second sealing layer 8. A third sealing layer forming step of forming a layer may be included.

(A) Gate Electrode Formation Step As shown in FIG. 2A, first, a metal thin film is formed on the substrate 1 to form the gate electrode 2.
In the present embodiment, the case where the gate electrode 2 is formed over the entire surface of the substrate 1 is described for the sake of simplicity. However, the gate electrode 2 is not limited to being formed on the entire surface of the substrate 1, and the patterned gate electrode 2 can be formed by using a photolithography method, a mask film forming method, or the like. is there.
Further, advantages of patterning the gate electrode 2 include, for example, that element isolation is possible and that high-speed operation of the element can be expected by reducing gate parasitic capacitance.

(B) Gate Insulating Layer Formation Step Next, as shown in FIG. 2B, the gate insulating layer 3 is formed so as to overlap the gate electrode 2. For the production of the gate insulating layer 3, various methods such as normal vacuum deposition, sputter film formation, CVD method, spin coating method, or ink jet method can be used.

(C) Source / Drain Electrode Forming Step Subsequently, as shown in FIG. 2C, the source electrode 4 and the drain electrode 5 are formed on the gate insulating film 3 at intervals.
For forming the patterns of the source electrode 4 and the drain electrode 5, a printing method such as an ink jet method can be used in addition to a photolithography method, an etching process, and a lift-off process used in a normal semiconductor process. In addition, various methods such as a normal vacuum vapor deposition method, a sputter film formation method, and a printing method can be used for forming the material constituting the source electrode 4 and the drain electrode 5.

  The distance (channel length) between the source electrode 4 and the drain electrode 5 is 10 nm to 200 μm, preferably 50 nm to 50 μm, from the viewpoints of high-speed response, element miniaturization, and ease of fabrication. .

  The source electrode 4 and the drain electrode 5 are preferably 10 nm to 1 cm on a side, preferably 100 nm to 1 mm, from the viewpoint of device miniaturization and ease of fabrication.

  The width of the channel is preferably 10 nm to 1 cm, preferably 100 nm to 1 mm, from the viewpoint of securing the amount of current, miniaturization of the element, and ease of manufacture.

(D) Organic Semiconductor Layer Formation Step Next, as shown in FIG. 2D, the organic semiconductor layer 6 is formed so as to overlap the source electrode 4 and the drain electrode 5.
The organic semiconductor layer 6 can be produced using, for example, a vacuum vapor deposition method by resistance heating. Moreover, when the organic semiconductor layer 6 is comprised from a soluble material, it is possible to produce the organic semiconductor layer 6 using general methods, such as a coating method or a printing method. From the viewpoint of parasitic capacitance and the like, the organic semiconductor layer 6 is preferably formed by patterning so as to overlap the source electrode 4 and the drain electrode 5.

(E) First Sealing Layer Forming Step Subsequently, as shown in FIG. 2E, the first sealing layer 7 is formed so as to cover the organic semiconductor layer by dividing it with the channel portion.
For the formation of the pattern of the first sealing layer 7, a printing method such as an ink jet method or a screen printing method, a photolithography method used in a normal semiconductor process, an etching process, a lift-off process, or the like can be used. In addition, various methods such as a normal vacuum vapor deposition method, a sputter film formation method, and a printing method can be used for forming the first sealing layer 7.

(F) Second Sealing Layer Formation Step Finally, as shown in FIG. 2F, the second sealing layer 8 including the channel portion and covering the organic semiconductor layer is formed.
For the production of the second sealing layer 8, various film forming methods such as normal vacuum vapor deposition, sputter film formation, CVD method, spin coating method, or ink jet method can be used.

(G) Third Sealing Layer Forming Step The organic transistor 100 of the present invention is formed by the steps as described above, but a third sealing layer forming step as shown here may be further performed thereafter.
In the third sealing layer forming step, as shown in FIG. 2G, a third sealing layer 9 is formed to cover the channel portion with the second sealing layer interposed therebetween.

For the formation of the pattern of the third sealing layer 9, a printing method such as an ink jet method or a screen printing method, a photolithography method used in a normal semiconductor process, an etching process, a lift-off process, or the like can be used. In addition, various methods such as a normal vacuum deposition method, a sputtering film forming method, and a printing method can be used for forming the third sealing layer 9.
The organic thin film transistor 100 according to the present embodiment can be manufactured through the steps as described above.

Hereinafter, the present invention will be specifically described by way of examples.
Example 1
In Example 1, an example of manufacturing an organic thin film transistor 100 using pentacene, which is a p-type organic semiconductor material, as shown in FIG. 3 will be described. 3A is a top view, and FIG. 3B is a cross-sectional view taken along line BB ′ in FIG. However, only the outline of the second sealing layer 8 in FIG. 3A is shown so that the configuration can be easily understood.

4 is a cross-sectional view showing process steps in the method of manufacturing the organic thin film transistor 100 of FIG.
Hereinafter, the process steps of the method of manufacturing the organic thin film transistor 100 shown in FIG. 3 will be described based on FIGS.

First, as shown in FIG. 4A, an N-type single crystal silicon substrate is used as a substrate 11 that also serves as a gate electrode, and a silicon thermal oxide film is formed on the substrate 11 as a gate insulating film 3 to a thickness of 100 nm. Formed with. Next, in order to produce the source electrode 4 and the drain electrode 5 on the gate insulating film 3, a photoresist film 12 having an opening was produced.
Next, as shown in FIG. 4B, a metal thin film 13 having a two-layer structure of gold (Au) and a gold-nickel alloy (Au / Ni = 97% / 3%) is formed to a thickness of 60 nm by vacuum deposition. Vapor deposited.

  Thereafter, in order to remove the photoresist film 12, a lift-off process of immersing the substrate 11 in an N-methylpyrrolidone solvent was performed, and the metal thin film 13 made of unnecessary gold laminated on the photoresist film 12 was removed. Thus, the source electrode 4 and the drain electrode 5 were formed on the gate insulating film 3 as shown in FIG. The lengths of the source electrode 4 and the drain electrode 5 were 500 μm in the channel length direction and 1000 μm in the channel width direction. The channel length was 50 μm.

  Subsequently, as shown in FIG. 4D, an organic semiconductor layer 6 was formed using a p-type organic semiconductor material pentacene. In Example 1, using a vacuum vapor deposition method, vapor deposition was performed through a mask having a predetermined opening under the condition of a substrate temperature of 50 ° C., thereby producing an organic semiconductor layer 6 having a thickness of 100 nm. The organic semiconductor layer had a length of 400 μm in the channel length direction and a channel width of 500 μm.

Then, as shown in FIG. 4E, an aqueous solution of polyvinyl alcohol is dropped by a dispenser, and annealing is performed in nitrogen at 90 ° C. for 1 hour, so that the organic semiconductor layer 6 is covered by being divided at the channel portion. A first sealing layer 7 was formed.
Finally, as shown in FIG. 4F, parylene is deposited to a thickness of 200 nm by a vapor deposition method using a metal mask so as to cover the organic semiconductor layer 6 including the channel portion, and the second sealing layer 8. To form an organic thin film transistor.

Example 2
An organic transistor was produced in exactly the same manner as in Example 1, except that the polyvinyl alcohol used in forming the first sealing layer 7 in Example 1 was changed to parylene and the dropping by the dispenser was changed to vapor deposition.

Example 3
An organic transistor was produced in exactly the same manner as in Example 1, except that the polyvinyl alcohol solution used in forming the first sealing layer 7 in Example 1 was replaced with an N-methylpyrrolidone solution of polyimide.

Comparative Example 1
In the organic thin film transistor of Comparative Example 1 shown in FIG. 5, a first full sealing layer 17 is formed so as to cover the entire organic semiconductor layer 6 without being divided at the channel portion, and an organic semiconductor layer is formed thereon. A second completely covering sealing layer 18 covering 6 is formed.

  In the organic thin film transistor of Comparative Example 1, instead of the first sealing layer 7, an aqueous solution of polyvinyl alcohol is dropped with a dispenser, and annealing is performed in nitrogen at 90 ° C. for 1 hour to cover the entire organic semiconductor layer 6. A first completely covering sealing layer 17 was formed. Further, the second completely encapsulating layer 18 is formed by forming a 200 nm film of parylene by vapor deposition using a metal mask so as to cover the organic semiconductor layer 6 via the first completely encapsulating layer 17. did. Except for this, an organic thin film transistor was fabricated in the same manner as in Example 1.

Comparative Example 2
The organic thin film transistor of Example 1 was manufactured in the same manner as in Example 1 except that the organic semiconductor layer 6 was formed and the subsequent step of forming the sealing layer was not performed. An organic thin film transistor having no sealing layer as shown in d) was produced.

Example 4
FIG. 6: shows the principal part structure of the organic thin-film transistor 100 which concerns on Example 4, (a) is a top view, (b) is CC 'line | wire sectional drawing in (a). However, only the outline of the second sealing layer 8 in FIG. 6A is shown so that the configuration can be easily understood.

In the organic thin film transistor of Example 4 shown in FIG. 6, the sealing layer is composed of a first sealing layer 7, a second sealing layer 8, and a third sealing layer 9 formed of a metal material. Has been.
Up to the second sealing layer 8 was formed in the same manner as in Example 1.
Thereafter, the third sealing layer 9 having a two-layer structure of gold (Au) and gold-nickel alloy (Au / Ni = 97% / 3%) is covered with the second sealing layer 8 through the channel portion. As described above, the film was formed to a thickness of 100 nm by a vacuum deposition method using a metal mask.

Example 5
In the organic thin film transistor of Example 5 shown in FIG. 7, the third sealing layer 9 is formed so as to cover the organic transistor. Up to the second sealing layer 8 was formed in the same manner as in Example 4.
Thereafter, a vacuum using a metal mask so that the third sealing layer 9 having a two-layer structure of gold (Au) and a gold-nickel alloy (Au / Ni = 97% / 3%) is covered on the organic transistor. A 100 nm film was formed by vapor deposition.

Example 6
In the organic thin film transistor of Example 6 shown in FIG. 8, the first sealing layer 7 and the third sealing layer 9 are made of a metal material.
The layers up to the organic semiconductor layer 6 were formed in the same manner as in Example 1.
Thereafter, a first sealing layer 7 having a two-layer structure of gold (Au) and a gold-nickel alloy (Au / Ni = 97% / 3%) is formed with a film thickness of 100 nm by vacuum deposition using a metal mask. did.

Thereafter, parylene was formed to a thickness of 200 nm by a vapor deposition method using a metal mask so as to cover the organic semiconductor layer 6 including the channel portion, thereby forming a second sealing layer 8.
Finally, the third sealing layer 9 having a two-layer structure of gold (Au) and a gold-nickel alloy (Au / Ni = 97% / 3%) is connected to the channel portion via the second sealing layer 8. A 100 nm film was formed by vacuum deposition using a metal mask so as to cover.

Example 7
FIG. 9: shows the principal part structure of the organic thin-film transistor 200 which concerns on Example 7, (a) is a top view, (b) is DD 'line sectional drawing in (a). However, only the outline of the second sealing layer 28 in FIG. 9A is shown so that the configuration can be easily understood.
The organic thin film transistor of Example 7 has a structure in which a gate electrode is patterned. The first sealing layer 27 and the third sealing layer 29 are made of a metal material.

Hereinafter, process steps of the method for producing the organic thin film transistor of Example 7 will be described.
First, an aluminum silicon alloy film (Al / Si = 90% / 10%) having a thickness of 40 nm was formed on the glass substrate 21 by sputtering.
Subsequently, the aluminum silicon (Al—Si) alloy film was patterned into a desired shape using photolithography and an etching process, and the gate electrode 22 was formed.

Next, a silicon oxide film (SiO ₂ ) was formed to a thickness of 200 nm on the gate electrode 22 by a sputtering method, so that a gate insulating film 23 was produced.
Subsequently, similarly to Example 1, a source electrode 24 and a drain electrode 25 made of gold were formed to a thickness of 60 nm by using a lift-off method using a resist film (not shown).
The lengths of the source electrode 24 and the drain electrode 25 were 500 μm in the channel length direction and 1000 μm in the channel width direction. The channel length was 50 μm.

Then, in the same manner as in Example 1, pentacene was formed as the organic semiconductor layer 26 by a vacuum evaporation method with a film thickness of 100 nm. The length was 400 μm in the channel length direction, and the channel width was 500 μm.
Then, a first sealing layer 27 having a two-layer structure of gold (Au) and a gold-nickel alloy (Au / Ni = 97% / 3%) is formed with a film thickness of 100 nm by vacuum deposition using a metal mask. To form.

Subsequently, the second sealing layer 28 was formed by forming a 200-nm thick parylene film by vapor deposition using a metal mask so as to cover the organic semiconductor layer 6 including the channel portion.
Finally, a third sealing layer 29 having a two-layer structure of gold (Au) and a gold-nickel alloy (Au / Ni = 97% / 3%) is formed to a thickness of 100 nm by vacuum deposition using a metal mask. Formed with.
Through the process as described above, the organic transistor of Example 7 shown in FIG. 9 was produced.

With respect to the organic thin film transistor 200 manufactured as described above, a voltage changed from 0 V to −25 V is applied between both the gate electrode 22 and the source electrode 24 and between the third sealing layer 29 and the source electrode 24. Simultaneously, the drain current I _d flowing through the organic thin film transistor 200 was measured. The voltage between the source electrode 24 and the drain electrode 25 was fixed at -25V.

Comparative Example 3
A voltage changed from 0 V to −25 V was applied between the gate electrode 22 and the source electrode 24 for the organic thin film transistor 200 manufactured in Example 7, and the drain current I _d flowing through the organic thin film transistor 200 was measured. The voltage between the source electrode 24 and the drain electrode 25 was fixed at -25V.

Example 8
FIG. 10: shows the principal part structure of the organic thin-film transistor 100 concerning Example 8, (a) is a top view, (b) is EE 'arrow sectional drawing in (a). However, only the outline of the second sealing layer 8 in FIG. 10A is shown so that the configuration can be easily understood.
In the organic thin film transistor of Example 8 shown in FIG. 10, the first sealing layer 7 is divided in the channel width direction and covers other than the channel portion of the organic semiconductor layer.

The source electrode 4 and the drain electrode 5 were formed in the same manner as in Example 1.
Subsequently, the p-type organic semiconductor material pentacene is deposited using a vacuum deposition method through a mask having a predetermined opening at a substrate temperature of 50.degree. A semiconductor layer 6 was produced. The length of each part was 400 μm in the channel length direction and the channel width was 250 μm.

Then, an aqueous solution of polyvinyl alcohol is dropped by a dispenser, annealed in nitrogen at 90 ° C. for 1 hour, divided in each channel and also divided in the channel width direction to cover the organic semiconductor layer 6. The sealing layer 7 was formed.
Finally, parylene was formed to a thickness of 200 nm by a vapor deposition method using a metal mask so as to cover the organic semiconductor layer 6 including the channel portion, and a second sealing layer 8 was formed to manufacture an organic thin film transistor.

Comparison between Examples 1 to 6 and 8 and Comparative Examples 1 and 2 The mobility of the organic thin film transistors prepared in Examples 1 to 6 and 8 and Comparative Examples 1 and 2 is determined from the V _g − | I _d | ^1/2 curve. Asked. V _g is a voltage applied between the source electrode 4 and the substrate 11 and was changed from 0V to −30V. The voltage between the source electrode 4 and the drain electrode 5 was fixed at −30V. For the measurement, a semiconductor device analyzer B1500A manufactured by Agilent Technologies was used.

Further, after leaving in the air for 10 days, the mobility of each transistor was calculated again by the same measurement, and compared with the mobility immediately after fabrication.

  From Examples 1 to 3 and Comparative Examples 1 and 2, the organic semiconductor layer 6 is covered with the first sealing layer 7 divided at the channel portion, and the organic semiconductor layer 6 includes the channel portion with the second sealing layer 8. It was confirmed that deterioration of characteristics can be suppressed by the structure covering the substrate.

  Further, from Example 1 and Example 4, the sealing layer 10 covers the channel portion via the second sealing layer 8 in addition to the first sealing layer 7 and the second sealing layer 8. It was confirmed that the deterioration of the characteristics in the atmosphere can be further suppressed by having three sealing layers 9.

Moreover, from Example 4 and Example 5, it was confirmed that the characteristic deterioration in air | atmosphere can further be suppressed by the 3rd sealing layer 9 covering an organic transistor top.
Furthermore, from Example 1 and Example 6, it was confirmed that by forming the first sealing layer 7 with a metal, it is possible to improve the characteristics in addition to suppressing the characteristic deterioration of the organic thin film transistor.
Furthermore, from Example 1 and Example 8, it is confirmed that the characteristic degradation in the atmosphere can be further suppressed by dividing the first sealing layer 7 in the channel width direction and covering the organic semiconductor layer 6. It was done.

Comparison of Example 7 and Comparative Example 3 As is clear from the results shown in the table below, the organic thin film transistor 200 manufactured in Example 7 can suppress the deterioration of characteristics in the atmosphere, and in addition to the source electrode 23-second. By applying a voltage between the three sealing layers 29, the amount of drain current increases. That is, when the first sealing layer 27 and the third sealing layer 29 are made of metal materials, the third sealing layer 29 is the second gate electrode, and the second sealing layer 28 is the second gate. It was confirmed that it could be a double gate type organic thin film transistor regarded as an insulating film, and that more current could be obtained.

  The organic thin film transistor of the present invention can be suitably used for various electronic components because it can suppress deterioration of characteristics such as mobility. For example, it can be suitably used in the flexible display field.

100, 200 Organic thin-film transistor 1, 11, 21 Substrate 2, 22 Gate electrode 3, 23 Gate insulating film 4, 24 Source electrode 5, 25 Drain electrode 6, 26 Organic semiconductor layer

7, 27 First sealing layer 8, 28 Second sealing layer 9, 29 Third sealing layer 10 Sealing layer 12 Photoresist film 13 Metal thin film 17 First completely covering sealing layer 18 Second Fully encapsulated sealing layer 20 channel part

Claims (13)

The substrate has a gate electrode, a gate insulating film, a source electrode and a drain electrode, an organic semiconductor layer, and a sealing layer.
The organic semiconductor layer has a channel portion sandwiched between the source electrode and the drain electrode,
A first sealing layer that is divided by at least the channel portion and covers the organic semiconductor layer;
A second sealing layer including a channel portion and covering the organic semiconductor layer;
An organic thin film transistor, comprising: an optional third sealing layer that covers the second sealing layer.   The transistor according to claim 1, wherein the first sealing layer is divided in a channel length direction.   The transistor according to claim 1, wherein the first sealing layer is divided in a channel width direction.   4. The device according to claim 1, wherein the second sealing layer includes the channel portion and the source / drain electrodes, covers at least a part of the first sealing layer and covers the organic semiconductor layer. The transistor described in 1.   The third sealing layer according to any one of claims 1 to 4, wherein the third sealing layer covers at least the channel portion via the second sealing layer or the first sealing layer and the second sealing layer. The transistor described.   The transistor according to claim 1, wherein the third sealing layer covers the organic semiconductor layer via the first sealing layer and the second sealing layer.   The transistor according to claim 1, wherein the first sealing layer is formed of an organic insulating material, a metal, or a metal alloy.   The transistor according to claim 1, wherein the third sealing layer is formed of an organic insulating material, a metal, or a metal alloy.   The first and third sealing layers are independently selected from organic insulating materials made of parylene, polyimide, polyvinyl alcohol and polyvinylphenol, or metals made of gold, silver, copper and aluminum or these 9. The transistor according to claim 1, wherein the transistor is made of a material selected from metal alloys. Forming a gate electrode on the substrate; manufacturing a gate insulating film; forming a source electrode and a drain electrode; forming an organic semiconductor layer; and a sealing layer covering the organic semiconductor layer And forming a process,
In the step of forming the sealing layer, the first sealing layer is formed so as to cover the organic semiconductor layer by dividing at least a channel portion sandwiched between the source electrode and the drain electrode of the organic semiconductor layer. Process,
Forming a second sealing layer so as to cover the organic semiconductor layer, including the channel portion;
Forming an optional third sealing layer covering the second sealing layer. A method of manufacturing an organic thin film transistor, comprising: The step of forming the sealing layer includes
Forming the first sealing layer;
Forming the second sealing layer;
11. The method according to claim 10, further comprising forming a third sealing layer by forming a material for forming the third sealing layer so as to cover the channel portion via the second sealing layer. Transistor manufacturing method. Forming the first sealing layer comprises:
12. The method for manufacturing a transistor according to claim 10, wherein the first sealing layer is formed using a metal or a metal alloy.   The method for manufacturing a transistor according to claim 10, wherein the step of forming the third sealing layer is a step of forming the third sealing layer from a metal or a metal alloy material.

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