JP2007180471A - Thin film transistor and manufacturing method thereof - Google Patents

Abstract

An object of the present invention is to provide a thin film transistor and a method for manufacturing the thin film transistor that are high definition, have good transistor characteristics, are flexible, can handle a large area, and are mass-productive.
A thin film transistor having a layer structure including a gate electrode of a lower electrode, a source electrode and a drain electrode of an upper electrode, a gate insulating layer of an insulating layer, and a semiconductor active layer of an active layer made of a semiconductor on a base material. , At least the upper electrode is on a second base material different from the base material, for example, a concave portion, a convex portion, or a flat portion of the base material having a concave portion, a convex portion, or a flat portion on the surface, and an electrode material After being formed, the thin film transistor is transferred onto the gate insulating layer of the base material to form a source electrode and a drain electrode of the upper electrode.
[Selection] Figure 1

Description

  The present invention relates to a field effect thin film transistor and a method for manufacturing the same.

Conventionally, a thin film transistor is generally formed by laminating an electrode, an insulating layer, and a semiconductor layer on a glass substrate by vacuum deposition or sputtering in a pattern shape by photolithography or the like. Met. This manufacturing method requires an expensive apparatus, has a low throughput, and has been difficult to meet the recent demands for weight reduction of the base material and flexibility of the base material.

In response to this, in some manufacturing processes, attempts have been made to develop by an inkjet method or a printing method that is not a vacuum process. According to these methods, an expensive apparatus is not required, the throughput is satisfied, and a flexible and lightweight substrate such as plastic that can be continuously wound can be used. Inkjet methods and printing methods that do not use vacuum processes cannot use materials such as conventional metals and amorphous silicon.
Development of new materials is demanded, and in recent years, development of metal particle dispersions, conductive polymers, organic semiconductor materials, and the like applicable to these materials is also active.

However, in general, it has been difficult to perform high-definition patterning by the inkjet method or the printing method, and development of a new manufacturing method has been demanded. Further, particularly in the ink jet method, since the film thickness of the pattern to be obtained is very thin, for example, when a conductive material is patterned, there is a problem that desired conductivity cannot be obtained (see Patent Document 1). In addition, when a low-resistance electrode material with higher conductivity is required, heating and baking at a higher temperature has been demanded.

The known literature is described below.
JP 2003-309265 A

An object of the present invention is to provide a thin film transistor and a method for manufacturing the thin film transistor that are high definition, have good transistor characteristics, are flexible, can handle a large area, and are mass-productive.

The invention according to claim 1 of the present invention includes at least a gate electrode of a lower electrode, a source electrode and a drain electrode of an upper electrode, a gate insulating layer of an insulating layer, and a semiconductor active layer of an active layer made of a semiconductor on a substrate. A thin film transistor having a layer structure, wherein at least an upper electrode is formed on a second base material different from the base material and then transferred onto the base material.

The invention according to claim 2 of the present invention is the thin film transistor according to claim 1, wherein the second base material has an intaglio shape having a concave portion on a surface thereof.

The invention according to claim 3 of the present invention is the thin film transistor according to claim 1, wherein the second base material has a relief shape having a convex portion on the surface.

The invention according to claim 4 of the present invention is the thin film transistor according to claim 1, wherein the second base material is a planographic shape having a flat surface.

  The invention according to claim 5 of the present invention is the thin film transistor according to any one of claims 1 to 4, wherein the second base material is glass.

The invention according to claim 6 of the present invention includes at least a lower electrode, an upper electrode, an insulating layer,
In the method of manufacturing a thin film transistor for forming an active layer made of a semiconductor, at least the upper electrode is formed in the concave portion of the second base material according to claim 2 and then transferred onto the base material. It is a manufacturing method of the thin-film transistor characterized by including the process of forming a layer.

The invention according to claim 7 of the present invention is a method of manufacturing a thin film transistor in which an active layer made of at least a lower electrode, an upper electrode, an insulating layer, and a semiconductor is formed on a substrate. A method of manufacturing a thin film transistor, comprising a step of forming an upper electrode layer by a step of being transferred onto the base material after being formed on the convex portion of the second base material.

The invention according to claim 8 of the present invention is the method of manufacturing a thin film transistor in which an active layer made of at least a lower electrode, an upper electrode, an insulating layer and a semiconductor is formed on a base material, and at least the upper electrode according to claim 4 A method of manufacturing a thin film transistor, comprising a step of forming an upper electrode layer by a step of being formed on a part of a second substrate and then transferred onto the substrate.

  The invention according to claim 9 of the present invention is a method of manufacturing a thin film transistor in which an active layer made of at least a lower electrode, an upper electrode, an insulating layer and a semiconductor is formed on a substrate, wherein at least the upper electrode is according to claim 5. After being formed on the second base material, heating and baking are performed, and further, after forming an insulating layer on the upper electrode layer, the insulating layer and the upper electrode layer are transferred to the base material, A method of manufacturing a thin film transistor, comprising the step of simultaneously forming

According to the thin-film transistor of the present invention, at least the upper electrode is formed by forming a high-definition pattern on another substrate in advance and then transferring it, so that a thin-film transistor having high definition and good transistor characteristics can be obtained. Can be provided.

According to the method for manufacturing a thin film transistor of the present invention, since a winding process can be performed in the air by using a flexible base material, a thin film transistor capable of handling a large area and being mass-produced and a method for manufacturing the same are provided. can do.

 A thin film transistor and a manufacturing method thereof according to the present invention will be described below based on an embodiment.

The best mode for carrying out the present invention will be described in detail below with reference to the drawings, but the present invention is not limited thereto.

FIG. 1 is a sectional side view showing an embodiment of a thin film transistor according to the present invention. As shown in FIG. 1, after the thin film transistor 1 is provided with a gate electrode 3 as a lower electrode on a base material 2,
An insulating layer 4 and a source electrode 5 and a drain electrode 6 which are upper electrodes are formed, and a semiconductor layer 7 is provided in the vicinity of and between the source electrode 5 and the drain electrode 6.

The substrate 2 used in the present invention shown in FIG. 1 preferably has heat resistance, flatness, strength, and flexibility, and a plastic substrate is mainly suitable. For example, polyethylene terephthalate, polyethylene naphthalate, polyimide, polypropylene, polycarbonate, polyamide and the like can be used. By using a flexible substrate, a winding process can be performed in the air, so that a thin film transistor that can handle a large area and can be mass-produced can be manufactured.

Although the base material 2 may be used independently, depending on the case, you may provide the protective layer by an inorganic material and / or an organic material in the single side | surface or both surfaces of a base material. By providing the protective layer, gas barrier properties are imparted, and deterioration of the transistor due to moisture or oxygen can be prevented.

As the protective layer used on the substrate surface, known moisture or oxygen barrier materials, such as inorganic thin films such as aluminum oxide and silicon oxide, organic thin films such as polyvinyl chloride and polyvinylidene chloride, and their A composite film or a laminated film can be used, but is not limited thereto. These are preferably formed by a winding type coating or a winding type vacuum film forming method.

As the gate electrode 3, the source electrode 5, and the drain electrode 6, known materials such as gold, silver, copper, chromium, titanium, indium tin oxide, and conductive polymer can be appropriately used.
The gate electrode 3 can be produced by a vacuum deposition method, but it is preferable to use a known printing method such as gravure printing or screen printing using a dispersion of metal particles.

As the insulating layer 4, a known organic or inorganic insulating material can be used. For example,
Organic materials such as polyethylene terephthalate, polyethylene naphthalate, polypropylene, cycloolefin polymer, polyamide, polyethersulfene, polymethyl methacrylate, polycarbonate, polyallylate, silicon dioxide, silicon nitride,
Inorganic materials such as aluminum oxide can be used, but are not limited thereto.

The insulating layer can be formed by a known method such as spin coating, dip coating, screen printing, gravure printing, letterpress printing, planographic printing, ink jet method, CVD method or sol-gel method. In particular, a thin film transistor that can be applied to a large area and can be mass-produced can be obtained by performing the winding method in the air.

As the semiconductor layer 7, a known organic or inorganic semiconductor material can be used. For example, perylene tetracarboxyl dianhydride, polytriallylamine, naphthalene tetracarboxyl dianhydride, copper phthalocyanine, copper phthalocyanine, tetracene, pentacene, thiophene oligomer, α-sexithiophene, regioregular poly (thiophene) ), And inorganic materials such as zinc oxide, cadmium selenide, and indium gallium oxide can be used, but are not limited thereto.

The semiconductor layer can be formed by a known method such as spin coating, dip coating, screen printing, gravure printing, letterpress printing, planographic printing, ink jet method, or vacuum deposition. In particular, a thin film transistor that can be applied to a large area and can be mass-produced can be obtained by performing the winding method in the air.

In the present invention, a protective layer may be further provided on the semiconductor layer 7 as necessary. As the protective layer, a material having a barrier property against moisture and oxygen is preferable, and known materials such as polyvinyl chloride, polyvinylidene chloride, polyvinyl phenol, polyvinyl alcohol, acrylic polymer, and epoxy polymer can be appropriately used. However, it is not limited to these.

 In the present invention, a method has been invented in which the formation accuracy of the upper electrode layer of the thin film transistor is made highly precise and the transistor characteristics are improved. This will be specifically described below.

FIG. 2 is a side sectional view showing an embodiment in which an upper electrode layer is formed on the second substrate of the present invention. As shown in FIG. 2, the source electrode 5 and the drain electrode 6 are provided in the recessed part of the 2nd base material 8a.

The second substrate 8a is formed with a recess by patterning by a photolithography method, mechanical cutting by FIB or the like, or a nanoimprinting method. Especially the processing accuracy is
It is preferable to have a definition of 10 microns or less, and the accuracy controls the positional accuracy of the upper electrode layer, particularly the distance between the source electrode 5 and the drain electrode 6.

FIG. 3 is a side cross-sectional view showing another embodiment in which an upper electrode layer is formed on the second substrate of the present invention. As shown in FIG. 3, the source electrode 5 and the drain electrode 6 are provided on the convex portion of the second substrate 8b.

The second base material 8b forms convex portions by patterning by photolithography, mechanical cutting by FIB or the like, or nanoimprinting. In particular, it is preferable to have a definition of 10 microns or less, and the accuracy controls the positional accuracy of the upper electrode layer, particularly the distance between the source electrode 5 and the drain electrode 6.

FIG. 4 is a sectional side view showing another embodiment of the state in which the upper electrode layer is formed on the second substrate of the present invention. As shown in FIG. 4, the source electrode 5 and the drain electrode 6 are provided in a part of surface of the 2nd base material 8c.

The second base material 8c forms a lithographic plate having a parent electrode material portion and a sparse electrode material portion on the lithographic plate by a method such as plasma treatment using a photomask. The positional accuracy of the parent electrode material part controls the positional accuracy of the upper electrode layer, particularly the distance between the source electrode 5 and the drain electrode 6.

As the second base materials 8a, 8b, and 8c, general plastic, glass, or metal can be used. These are appropriately selected depending on the process. As general plastics, polymethacrylate, polyacrylate, polyethylene terephthalate, polydimethylsiloxane, polypropylene and the like can be used, but are not limited thereto.

Next, a method for forming the source electrode 5 and the drain electrode 6 will be described in detail. In FIG. 2, the 2nd base material 8a has a recessed part. The concave portion is formed by patterning by a photolithography method, mechanical cutting by FIB or the like, or a nano-imprinting method, but is not limited thereto, and can be used as long as high-precision processing is possible. In particular, the processing accuracy preferably has a fineness of 10 microns or less. The electrode material is embedded in the concave portion of the base material by roll coating or spray coating, etc., and the electrode material adhering to the non-concave portion is removed by a doctor, etc. Thus, the electrode material is transferred. In this case, both the base material 2 and the second base material 8a may be planar, or one may be roll-shaped.

  As another aspect, when glass is used as the second base material 8a, the base material 2 on which the gate electrode is formed after the electrode material is formed in the recess, followed by heating and baking, further forming the insulating layer. And the insulating layer and the electrode material are transferred by heat or pressure, or through an adhesive layer. The heating temperature at the time of heating and baking is preferably 100 ° C. or higher, more preferably 150 ° C. or higher. By performing the heating and baking, the resistance value of the electrode material is reduced, and the electrode material has higher conductivity, and the transistor characteristics can be improved.

Next, in FIG. 3, the 2nd base material 8b has a convex part. The convex portion is formed by patterning by a photolithography method, mechanical cutting by FIB or the like, or a nano-imprinting method, but is not limited thereto, and can be used if high-precision processing is possible. In particular, it is preferable to have a definition of 10 microns or less. After the electrode material is attached to the convex portions of the base material by roll coating or spray coating, it is brought into close contact with the base material 2 on which the insulating layer is formed, and the electrode material is transferred by pressure or heat. In this case, both the base material 2 and the second base material 8b may be planar, or one may be roll-shaped.

  As another embodiment, when glass is used as the second base material 8b, the base material on which the gate electrode is formed after the electrode material is formed on the convex portion, followed by heating and baking, further forming the insulating layer. The insulating layer and the electrode material are transferred by being in close contact with 2 and through heat or pressure or an adhesive layer. The heating temperature at the time of heating and baking is preferably 100 ° C. or higher, more preferably 150 ° C. or higher. By performing the heating and baking, the resistance value of the electrode material is reduced, and the electrode material has higher conductivity, and the transistor characteristics can be improved.

Next, in FIG. 4, the second substrate 8c is a lithographic plate. A master electrode material portion and a sparse electrode material portion are provided on a lithographic plate, and after the electrode material is adhered to the parent electrode material portion, the electrode material is transferred by pressure or heat, etc., in close contact with the base material 2 on which the insulating layer is formed. To do. In this case, both the base material 2 and the second base material 8c may be planar, or one may be roll-shaped. As a method of forming the parent electrode material portion and the sparse electrode material portion on the lithographic plate, a known method such as plasma treatment using a mask can be appropriately used.

  In another embodiment, when glass is used as the second base material 8c, an electrode material is formed on the parent electrode material portion, then heated and fired, and after further forming an insulating layer, a gate electrode is formed. The insulating layer and the electrode material are transferred by being in close contact with the substrate 2 and through heat or pressure or an adhesive layer. The heating temperature at the time of heating and baking is preferably 100 ° C. or higher, more preferably 150 ° C. or higher. By performing the heating and baking, the resistance value of the electrode material is reduced, and the electrode material has higher conductivity, and the transistor characteristics can be improved.

According to the method for forming the source electrode 5 and the drain electrode 6 shown in FIGS. 2 to 4, the definition of the electrode is determined by the definition of the plate used as the second substrate. It is possible to achieve a fineness that is difficult with general printing methods. Thereby, the distance between the source electrode and the drain electrode can be shortened, and the transistor characteristics are improved. In particular, when an intaglio plate is used, various conductivity can be obtained by controlling the depth of the plate, and transistor characteristics can be improved. Furthermore, particularly when glass is used as the second base material, it is possible to heat and sinter after forming the electrode material, so that the organic matter in the metal particle dispersion is burned out, or the metal particles are As a result of sintering, etc., the resistance value of the electrode material decreases, the electrode material becomes more conductive, and the transistor characteristics are further improved.

1 is a side sectional view showing an embodiment of a thin film transistor according to the present invention. FIG. 5 is a side cross-sectional view showing an example of a state in which an upper electrode layer is formed on a second substrate of the present invention. It is a sectional side view which shows another Example of the state which formed the upper electrode layer on the 2nd base material of this invention. It is a sectional side view which shows another Example of the state which formed the upper electrode layer on the 2nd base material of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Thin-film transistor 2 ... Base material 3 ... Gate electrode (lower electrode)
4 ... Insulating layer 5 ... Source electrode (upper electrode)
6 ... Drain electrode (upper electrode)
7. Semiconductor layer (semiconductor active layer)
8a, 8b, 8c ... second base material

Claims (9)

A thin film transistor having a layer structure including at least a gate electrode of a lower electrode, a source electrode and a drain electrode of an upper electrode, a gate insulating layer of an insulating layer, and a semiconductor active layer of an active layer made of a semiconductor on a base material, Is formed on a second substrate different from the substrate and then transferred onto the substrate. 2. The thin film transistor according to claim 1, wherein the second base material has an intaglio shape having a concave portion on a surface thereof. The thin film transistor according to claim 1, wherein the second base material has a relief pattern having a convex portion on a surface thereof. 2. The thin film transistor according to claim 1, wherein the second substrate has a planographic shape with a flat surface.   The thin film transistor according to claim 1, wherein the second base material is glass. In the method of manufacturing a thin film transistor in which at least a lower electrode, an upper electrode, an insulating layer, and an active layer made of a semiconductor are formed on a base material, at least the upper electrode is formed in the concave portion of the second base material according to claim 2. Thereafter, a method of manufacturing a thin film transistor, comprising a step of forming an upper electrode layer by a step of being transferred onto the substrate. In the method of manufacturing a thin film transistor in which at least a lower electrode, an upper electrode, an insulating layer, and an active layer made of a semiconductor are formed on a base material, at least the upper electrode is formed on the convex portion of the second base material according to claim 3. And then forming the upper electrode layer by a process of transferring onto the substrate. 5. In the method of manufacturing a thin film transistor, wherein at least a lower electrode, an upper electrode, an insulating layer, and an active layer made of a semiconductor are formed on a substrate, at least the upper electrode is formed on a part of the second substrate according to claim 4. And a step of forming an upper electrode layer by the step of being transferred onto the base material.   In the manufacturing method of the thin-film transistor which forms the active layer which consists of at least a lower electrode, an upper electrode, an insulating layer, and a semiconductor on a base material, after at least an upper electrode is formed on the second base material according to claim 5 Characterized in that it includes a step of simultaneously forming an insulating layer and an upper electrode layer by a step of performing heat baking and further forming an insulating layer on the upper electrode layer and then transferring to the base material. A method for manufacturing a thin film transistor.

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