JP2005123290A - Thin film transistor and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED To provide a thin film transistor having a stable gate insulating film and a manufacturing method thereof with high production efficiency and a simple process.
A thin-film transistor comprising a gate electrode formed on at least one surface of a gate insulating film made of a resin film substrate, and a source / drain electrode and a semiconductor layer formed on the other surface, and a method of manufacturing the same. is there. 2. The thin film transistor according to claim 1, wherein the gate insulating film is a resin film in which a thin film layer made of an organic material or an inorganic material is formed as the gate insulating film.
[Selection] Figure 1

Description

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

  In recent years, electronic paper, RFID tags, and the like have attracted attention. These require transistors. However, the current transistor manufacturing process requires a vacuum process and a photo process, and its manufacturing cost is high. Therefore, in order to make them real, it is necessary to produce them at a lower cost and in a larger amount than conventional transistors. There is also a demand for forming a transistor on a flexible substrate.

  For this reason, a transistor using a printing method, in particular, an organic transistor has attracted attention (for example, see Patent Document 1). This method is attracting attention for the following reasons.

  Since processing at a low temperature is possible, a resin film can be used for the substrate. Further, since the semiconductor is an organic substance, it can be processed by a printing method using a solution obtained by dissolving the semiconductor in a solvent in the same manner as the printing ink. For this reason, a resin film is used as a base material, and this can be manufactured by a printing method in a so-called roll-to-roll process in which the film is supplied in a roll form to a manufacturing apparatus. Therefore, a large number of transistors can be manufactured at low cost.

  As a method of manufacturing a thin film transistor using an organic substance as a semiconductor, there are many reports using a silicon as a substrate and a thermal oxide film as a gate insulating film for a gate insulating film, and an example using a gate insulating film by a small number of solution processes. However, there are many methods for spin coating. The reason is that in spin coating, it is possible to easily obtain a thin film having a thickness of about 1 micrometer or less necessary as a gate insulating film.

  However, spin coating is difficult to apply to a roll-to-roll process, and it is necessary to form a gate insulating film by other methods. However, in this case, there are the following restrictions.

  That is, when the electrode is formed by the printing method, the screen printing method is optimal at present. In this case, the thickness is 10 to 20 from the practical viewpoint of avoiding the conductivity and disconnection of the electrode material. It is usually required to be micron.

  Therefore, in this case, that is, when the gate electrode is formed on a predetermined substrate by screen printing, it is necessary to form a gate insulating film on the surface with a uniform film thickness without a pinhole. In order to follow the unevenness of the substrate surface due to the thickness, the thickness of the gate insulating film needs to be the same as that of the gate electrode.

  However, in this case, since the gate insulating film becomes too thick, even if the thin film transistor can be actually formed, the gate voltage for operating the thin film transistor becomes very high, so that it is practically difficult to use.

  As one means for avoiding this, it is conceivable to use a resin film formed in advance as a gate insulating film.

  Non-patent documents 1 and 2 are examples of research reports for actually producing organic transistors by that means.

However, in these studies, vacuum processes and photo processes are used for semiconductors and electrodes, resulting in a high-cost transistor manufacturing process. There is no mention of a specific roll-to-roll process.
JP 2003-249656 A Garnier et al. Science Vol. 265, pages 1884 to 1886 (1994) Bonfiglio et al. Applied Physics Letters Vol. 82 No. 20 pages 3550 to 3552 (2003)

  The present invention has been made to solve such a problem, and it is an object of the present invention to provide a thin film transistor having a stable gate insulating film with a high production efficiency, a simple process, and a method for manufacturing the same.

  The invention of claim 1 is a thin film transistor comprising a gate electrode formed on one surface of a gate insulating film, a source / drain electrode formed on the other surface, and a semiconductor layer, wherein a resin film substrate is used as the gate insulating film. A thin film transistor characterized by being used.

  The invention according to claim 2 is the thin film transistor according to claim 1, wherein the resin film substrate used as the gate insulating film is a resin film in which a thin film layer made of an organic or inorganic material is formed.

  The invention according to claim 3 is the thin film transistor according to claim 1 or 2, wherein the support substrate is bonded to one surface of the resin film substrate.

  According to a fourth aspect of the present invention, there is provided a method of manufacturing a thin film transistor including a step of forming a gate electrode on one surface of a gate insulating film and a source / drain electrode and a semiconductor layer on the other surface. A thin film transistor manufacturing method characterized by using a base material.

  According to a fifth aspect of the present invention, there is provided a method of manufacturing a thin film transistor including a step of forming a gate electrode on one surface of a gate insulating film and a source / drain electrode and a semiconductor layer on the other surface. Using a base material, a source / drain electrode and a semiconductor layer are formed on one surface of the resin film base material, and a gate electrode previously provided on another support base material on the other surface of the resin film base material, A gate electrode is formed by facing and bonding to form a thin film transistor.

  The invention of claim 6 includes at least a step of unwinding a web-like resin film substrate, a step of forming a gate electrode on one surface of the unrolled resin film, and a source / drain electrode and a semiconductor layer on the other surface. And a step of winding up a resin film on which a gate electrode, a source / drain electrode and a semiconductor layer are formed.

  The invention of claim 7 includes at least a step of unwinding a web-shaped resin film substrate, a step of forming a source / drain electrode and a semiconductor layer on one surface of the unwound resin film, a source / drain electrode and a semiconductor A step of forming a gate electrode by facing and bonding a gate electrode forming side of another supporting base material on which a gate electrode is formed to the other surface of the resin base material on which the layer is formed, a gate electrode, a source / drain And a step of winding a resin film on which an electrode and a semiconductor layer are formed.

  The invention according to claim 8 is the method of manufacturing a thin film transistor according to any one of claims 4 to 7, wherein at least one of the gate electrode, the source / drain electrode, and the semiconductor layer is provided by a printing method. .

  A ninth aspect of the present invention is the method of manufacturing a thin film transistor according to the eighth aspect, wherein all of the gate electrode, the source / drain electrode, and the semiconductor layer are provided by a printing method.

  The invention according to claim 10 is the thin film transistor according to any one of claims 4 to 9, wherein the resin film substrate used as the gate insulating film is a resin film in which a thin film layer made of an organic material or an inorganic material is formed. It is a manufacturing method.

  According to the eleventh aspect of the present invention, when the gate electrode, the source / drain electrode, and the semiconductor layer are formed on the resin film substrate, the surface can be peeled away from the side opposite to the side on which the resin film substrate is formed. The method for producing a thin film transistor according to any one of claims 4 to 6, further comprising a step of bonding to a supporting substrate having a weak adhesive layer and peeling after forming.

  According to the present invention, by using a resin film base material as a gate insulating film, a sufficient performance can be obtained by an inexpensive and simple method, and a high-performance thin film transistor can be obtained. In addition, since a transistor can be manufactured by a roll-to-roll process, a large number of transistors can be manufactured at low cost.

  In the present invention, a gate electrode, an insulating film, a source / drain electrode, and a semiconductor layer are not provided on a conventional base material, but an insulating film base material is used for the insulating film, and the gate electrode, the source A drain electrode and a semiconductor layer are provided. Thus, even when a thin film transistor is manufactured using a printing method or the like that can be manufactured at low cost, the insulating film exhibits stable insulating properties, and a stable thin film transistor can be obtained. Further, since the conventional step of forming the gate insulating film can be omitted, the step can be simplified and the efficiency can be improved. Furthermore, it can be efficiently manufactured at a lower cost by using a roll-to-roll method or the like.

  As the resin film substrate used for the gate insulating film, a resin film such as polyester, polyimide, polyethylene, polypropylene, polyethersulfone, and polycarbonate can be used, but the polyester film is the best considering cost and thermal stability. is there.

  Moreover, it is preferable that the film thickness of the said resin film base material exists in the range of 0.1-2 micrometers. If it exceeds 2 μm, it will not operate unless the gate voltage is set to a high voltage when used as a thin film transistor, making it practically difficult to use. If it is thinner than 0.1 μm, the strength as a substrate cannot be maintained.

  As the electrode material used for the gate electrode and the source / drain electrode used in the present invention, known materials can be used. For example, a thick film paste using gold, silver, carbon, etc. as a conductive material, a paste made of an organometallic compound (organic resinate), an ink made of nanometal particles such as gold or silver, or polyaniline, polyethylene An organic conductive material such as dioxythiophene can be used, but a thick film paste is optimal in consideration of cost, conductivity, and the like.

  As a material of the semiconductor layer used in the present invention, a known material can be used. For example, high molecular organic semiconductor materials such as polythiophene, polyallylamine, fluorenebithiophene copolymers and derivatives thereof can be used.

  In addition, it is expected that carbon compounds having semiconductor characteristics, such as carbon nanotubes or fullerenes, semiconductor nanoparticle dispersions, and the like are also used as semiconductor materials.

  Moreover, in this invention, the thin film layer which consists of organic substance or an inorganic substance can be provided on a resin film base material for transistor characteristic improvement. For example, when forming a thin film for orienting a semiconductor material, it is preferable to form a polyimide thin film.

  In addition, a monomolecular film such as octyltrichlorosilane (OTS-8) can be formed for alignment. Further, benzocyclobutene, polyvinylphenol, silicon dioxide, or the like can be used as a thin film material for changing the dielectric constant.

  The thin film transistor of the present invention can be further laminated (laminated) with a supporting substrate.

  As such a supporting substrate, a resin film such as polyester, polyimide, polyethylene, polypropylene, polyethersulfone, and polycarbonate can be used, but a polyester film is the best considering cost and thermal stability.

  As a method for providing a gate electrode, a source / drain electrode, a semiconductor layer, a thin film layer made of an organic material or an inorganic material, a known vapor phase method or a wet method can be used. Among them, a printing method can be preferably used, and known printing methods such as letterpress printing, intaglio (gravure) printing, plate printing such as lithographic printing and screen printing, or ink jet printing, electrostatic printing, etc. Plateless printing can be used. Screen printing is best for electrode formation, and ink jet printing is best for semiconductor layer formation. For thin film layers made of organic or inorganic materials, flexographic printing and gravure printing are the best.

  The thin film transistor of the present invention is formed by using the resin film base material as a gate insulating film as a base material, and forming a gate electrode, a source / drain electrode, a semiconductor layer, and a thin film layer made of an organic or inorganic material by the method described above. is there. In the present invention, as shown in FIG. 1, a so-called roll-to-roll method is employed in which a web-shaped resin film substrate is unwound and a gate electrode is provided on one surface, and source / drain electrodes and a semiconductor layer are provided on the other surface. Can be used.

  Furthermore, as shown in FIG. 4, when forming a gate electrode, a source / drain electrode, and a semiconductor layer on a resin film substrate by a roll-to-roll method, it is opposite to the side on which the resin film substrate is formed before the formation. A support having a weak adhesive layer that can be peeled to the side can be bonded together and peeled off after formation.

  In addition, as shown in FIG. 5, a web-shaped resin film substrate is unwound, source / drain electrodes and a semiconductor layer are provided on one side, and a gate electrode is provided on the other side and supported on the gate electrode side. A gate electrode can also be formed by making a base material oppose and bonding together a support base material.

  As shown in FIG. 1, a 1.2 μm thick polyester film 10 (Toray mirror C12) as a resin film substrate (gate insulating film 10) is supplied in a roll form to a printing apparatus, and silver and carbon are supplied to the conductive material. The polymer thick film paste 20 (Asahi Chemical Laboratory) was printed using a screen printer 30. This was heated and cured at 150 ° C. for 30 minutes using a drying furnace 40 to form a gate electrode 51.

  Thereafter, the polymer thick film paste 20 was similarly printed on the back surface of the screen printing machine 30 and cured to form the source / drain electrodes 52.

  After that, an anisole solution of a polythiophene derivative was dropped as a semiconductor solution 60 on the source / drain electrode 52 by the ink jet apparatus 70 and dried at 100 ° C. in the atmosphere to obtain a semiconductor layer 53.

  As a result, a thin film transistor 50 having a polyester film 10 as a gate insulating film as shown in FIG. 2 was produced. When the electrical characteristics were measured, the results shown in FIG. 3 were obtained.

  As shown in FIG. 4, a polyester film (Toray Mirror C12) with a thickness of 1.2 μm is used as the resin film substrate (gate insulating film 10), and a weak adhesive film (Hitachi Chemical Hitarex adhesive film) with a thickness of 100 microns. ) Was laminated to obtain a support 80. Thereafter, a polymer thick film paste 20 (Asahi Chemical Research Laboratories) using silver and carbon as conductive materials was printed using a screen printer 30. After printing, the film was heated and cured at 150 ° C. for 30 minutes to form the gate electrode 51, and then the support 80 was peeled off.

  Subsequently, after laminating the support 80 on the gate electrode forming surface of the gate insulating film 10, the polymer thick film paste 20 was printed by a screen printer 30 and heat-cured to form the source / drain electrodes 52.

  Thereafter, an anisole solution of a polythiophene derivative is dropped as a semiconductor solution 60 on the source / drain electrode 52 by the ink jet apparatus 70 and dried at 100 ° C. in the atmosphere to form the semiconductor layer 53, and then the support 80 is peeled off. A thin film transistor 50 as shown in FIG. 2 was obtained.

As shown in FIG. 5, a 1.2 micron thick polyester film (Toray mirror C12) was used as the resin film constituting the resin film equipment (gate insulating film 10). A polyimide resin for forming the alignment film 100 was applied and dried to form a thin film having a thickness of 0.5 μm, and a rubbing process was performed using the buff 110 to form the alignment film 100.

  Thereafter, an anisole solution of a polythiophene derivative was printed as the semiconductor solution 60 using the inkjet device 70 and heated to 100 ° C. As a result, an oriented semiconductor layer 53 was formed by the action of the orientation film.

  Thereafter, a polymer thick film paste 20 (Asahi Chemical Research Laboratories) using silver and carbon as conductive materials was printed using a screen printer 30. After printing, the source / drain electrode 52 was formed by heating at 150 ° C. for 30 minutes to cure.

 Separately, a polymer thick film paste 20 (Asahi Chemical Research Laboratories) using silver and carbon as a conductive material on another supporting substrate (polyester film 120 (Toray mirror) having a thickness of 100 μm for the supporting body 80) is screen printer. 30 was used for printing. After printing, the gate electrode 51 was formed by heating at 150 ° C. for 30 minutes to cure.

  Thereafter, an adhesive 130 is applied to the film by a gravure printing machine 140, the film on which the semiconductor layer 53 and the source / drain electrodes 52 are printed and the film on which the gate electrodes are printed are aligned and bonded to each other in FIG. A thin film transistor 150 as shown was obtained.

It is the schematic of the process concerning one Example of this invention. It is sectional drawing which showed the structure of the thin-film transistor concerning one Example of this invention. It is an example of the characteristic evaluation result of the transistor produced by this invention It is the schematic of the process concerning one Example of this invention. It is the schematic of the process concerning one Example of this invention. It is sectional drawing which showed the structure of the thin-film transistor concerning one Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Gate insulating film 20 ... Polymer thick film paste 30 ... Screen printer 40 ... Drying furnace 50 ... Thin film transistor 51 ... Gate electrode 52 ... Source-drain electrode 53 ... Semiconductor layer 60 ... Semiconductor solution 70 ... Inkjet device 80 ... Support 90 ... Flexographic printing machine 100 ... Alignment film
110 ... Buff
120 ... Polyester film
130 ... Adhesive
140 ... Gravure printing machine
150 ... Thin film transistor

Claims (11)

  A thin film transistor comprising a gate electrode formed on one surface of a gate insulating film, a source / drain electrode formed on the other surface, and a semiconductor layer, wherein a resin film substrate is used as the gate insulating film Thin film transistor.   2. The thin film transistor according to claim 1, wherein the resin film substrate used as the gate insulating film is a resin film in which a thin film layer made of an organic material or an inorganic material is formed.   3. The thin film transistor according to claim 1, further comprising a support base material bonded to one surface of the resin film base material.   In a thin film transistor manufacturing method including a step of forming a gate electrode on one surface of a gate insulating film and a source / drain electrode and a semiconductor layer on the other surface, a resin film substrate is used as the gate insulating film A method of manufacturing a thin film transistor.   In a method of manufacturing a thin film transistor including a step of forming a gate electrode on one surface of a gate insulating film and a source / drain electrode and a semiconductor layer on the other surface, a resin film substrate is used as the gate insulating film, and the resin By forming source / drain electrodes and a semiconductor layer on one surface of the film substrate, facing the gate electrode provided on the other support substrate in advance, and bonding the other surface of the resin film substrate, A method of manufacturing a thin film transistor, comprising forming a gate electrode.   At least a step of unwinding a web-shaped resin film substrate, a step of forming a gate electrode on one side of the unwound resin film, a source / drain electrode and a semiconductor layer on the other side, a gate electrode, a source / drain A method for producing a thin film transistor, comprising: winding a resin film on which an electrode and a semiconductor layer are formed.   At least a step of unwinding a web-shaped resin film substrate, a step of forming a source / drain electrode and a semiconductor layer on one surface of the unwound resin film, a resin base on which the source / drain electrode and the semiconductor layer are formed A step of forming a gate electrode on the other surface of the material by facing and bonding the gate electrode forming side of another supporting base material on which the gate electrode is formed, and forming a gate electrode, a source / drain electrode, and a semiconductor layer A method for producing a thin film transistor, comprising the step of winding up a resin film.   8. The method of manufacturing a thin film transistor according to claim 4, wherein at least one of the gate electrode, the source / drain electrode, and the semiconductor layer is provided by a printing method.   9. The method of manufacturing a thin film transistor according to claim 8, wherein all of the gate electrode, the source / drain electrode, and the semiconductor layer are provided by a printing method.   The method for producing a thin film transistor according to any one of claims 4 to 9, wherein the resin film substrate used as the gate insulating film is a resin film in which a thin film layer made of an organic material or an inorganic material is formed.   When forming the gate electrode, source / drain electrode, and semiconductor layer on the resin film substrate, a weakly adhesive layer that can be peeled off on the surface opposite to the side on which the resin film substrate is formed before the formation. A method for producing a thin film transistor according to any one of claims 4, 6 and 8 to 10, further comprising a step of bonding to a supporting base material having a separation and peeling after forming.

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