JP2005251809A - Thin film transistor, method of manufacturing the same, circuit thereof, electronic device, and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an easy manufacturing method of a thin film transistor having excellent transistor properties without causing the deterioration and degradation of a source electrode and a drain electrode, and to provide a thin film transistor manufactured by the same, and a thin film transistor circuit, an electronic device, and an electronic apparatus equipped with the thin film transistors, respectively. <P>SOLUTION: The manufacturing method of the thin film transistor comprises processes of forming a thin resist layer 8 which has openings having such shapes as to correspond to the source electrode 3 and the drain electrode 4, and has a thickness thinner than that of the source electrode 3 and the drain electrode 4 to be formed; supplying a liquid material 9 containing a conductive material and/or its precursor and a water-based solvent into the opening of the resist layer 8 in such a manner that the thickness may be larger than that of the resist layer 8; obtaining the source electrode 3 and the drain electrode 4 by removing the water-based solvent from the liquid material 9; and removing the resist layer 8. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a thin film transistor, a thin film transistor, a thin film transistor circuit, an electronic device, and an electronic apparatus.

In recent years, development of a thin film transistor using an organic material (organic semiconductor material) that exhibits semiconducting electrical conduction has been promoted. This thin film transistor has advantages such as being suitable for reduction in thickness and weight, flexibility, and low material cost, and is expected as a switching element for flexible displays and the like.
As this thin film transistor, a source electrode and a drain electrode are formed on a substrate, and an organic semiconductor layer, a gate insulating layer, and a gate electrode are stacked in this order on these electrodes.

In such a thin film transistor, conventionally, a source electrode and a drain electrode are formed by using a vacuum deposition method or the like (see, for example, Patent Document 1).
However, in this case, a large-scale device such as a vacuum device is required, and energy consumption required for forming these electrodes is large. For this reason, when the source electrode and the drain electrode are formed using such a method, the manufacturing efficiency of the thin film transistor is lowered and the cost is increased.

On the other hand, a method is widely used in which a source electrode and a drain electrode are formed by supplying a liquid material containing constituent materials of these electrodes onto a substrate.
Specifically, a resist layer having openings in regions where source and drain electrodes are formed on the substrate is formed, and a liquid material containing a material for forming these electrodes is supplied into the openings.

Next, after drying the liquid material, the resist layer is removed (peeled) to form these electrodes.
However, this method generally forms a resist layer that is much thicker than the thickness of the source and drain electrodes to be formed. Therefore, when this resist layer is removed (peeled) with a stripping solution or the like, these electrodes are deteriorated or deteriorated by the stripping solution or the like, resulting in a problem that the characteristics of the thin film transistor are deteriorated.

JP 2003-28283 A

  An object of the present invention is to provide a thin film transistor manufacturing method capable of manufacturing a thin film transistor excellent in transistor characteristics without causing deterioration or deterioration of a source electrode and a drain electrode.

  Moreover, it is providing the thin-film transistor manufactured by this manufacturing method of a thin-film transistor, a thin-film transistor circuit provided with this thin-film transistor, an electronic device, and an electronic device.

Such an object is achieved by the present invention described below.
The thin film transistor manufacturing method of the present invention includes a source electrode, a drain electrode, a gate electrode, an organic semiconductor layer, and a gate insulating layer that insulates the gate electrode from the source electrode and the drain electrode. A thin film transistor manufacturing method for manufacturing a thin film transistor having:
A first step of forming a resist layer having an opening having a shape corresponding to the source electrode and the drain electrode and having a thickness smaller than the thickness of the source electrode and the drain electrode to be formed;
A second step of supplying a liquid material containing a conductive material and / or a precursor thereof and an aqueous solvent into the opening of the resist layer so as to be thicker than the thickness of the resist layer;
A third step of removing the aqueous solvent from the liquid material to obtain the source electrode and the drain electrode;
It has the 4th process of removing the said resist layer, It is characterized by the above-mentioned.
As a result, a thin film transistor which is suitably prevented or suppressed from being altered or deteriorated in the source electrode and the drain electrode and has excellent transistor characteristics can be manufactured by a simple method.

In the thin film transistor manufacturing method of the present invention, when the thickness of the source electrode and the drain electrode to be formed is X [nm] and the thickness of the resist layer is Y [nm], X / Y is 2-10. It is preferable to satisfy this relationship.
By satisfying such a relationship, it is possible to more reliably prevent or suppress the deterioration and deterioration of the source electrode and the drain electrode due to the process of removing the resist layer.

The thin film transistor manufacturing method of the present invention preferably includes a water repellent treatment step of performing a water repellent treatment on the surface of the resist layer opposite to the substrate prior to the second step.
Thereby, even if the thickness of the liquid material is supplied so as to be thicker than the thickness of the resist layer in the second step, the liquid material is prevented from shifting to the surface of the resist layer opposite to the substrate. Is done.

In the thin film transistor manufacturing method of the present invention, the water repellent treatment is preferably a fluorine plasma treatment.
According to the fluorine plasma treatment method, the upper surface of the resist layer can be uniformly fluorinated almost entirely, that is, the water repellency can be imparted uniformly (evenly) to the upper surface of the resist layer.

In the method for manufacturing a thin film transistor of the present invention, it is preferable to have a hydrophilic treatment step of performing a hydrophilic treatment in the opening prior to the second step.
Thereby, in the second step, when a liquid material is supplied into the opening of the resist layer, the liquid material spreads uniformly in the opening.
In the method for manufacturing a thin film transistor of the present invention, the hydrophilic treatment is preferably oxygen plasma treatment.
According to the oxygen plasma treatment method, hydrophilicity can be easily and reliably imparted into the opening of the resist layer.

In the method for manufacturing a thin film transistor of the present invention, in the second step, the liquid material is preferably supplied by a droplet discharge method.
According to the droplet discharge method, it is possible to reliably supply the liquid material into the opening and more reliably prevent diffusion into the resist layer.
In the thin film transistor manufacturing method of the present invention, in the second step, the contact angle of the liquid material with respect to the resist layer is A [°], and the contact angle of the liquid material with respect to the opening is B [°]. In this case, it is preferable to satisfy the relationship of AB ≧ 15.
Thereby, it can prevent more reliably that the liquid material supplied in the opening part so that it may become thicker than the thickness of a resist layer diffuses (transfers) to the upper surface of a resist layer.

In the thin film transistor manufacturing method of the present invention, in the third step, the temperature at which the aqueous solvent is removed is preferably 20 to 200 ° C.
Thereby, the aqueous solvent contained in a liquid material can be removed reliably.
In the thin film transistor manufacturing method of the present invention, in the fourth step, the resist layer is preferably removed by plasma treatment.
According to the plasma treatment, the resist layer can be easily removed while suppressing deterioration and deterioration of the source electrode and the drain electrode.

In the thin film transistor manufacturing method of the present invention, the plasma treatment is preferably an oxygen plasma treatment.
Thus, the resist layer can be easily removed while more reliably suppressing the deterioration and deterioration of the source electrode and the drain electrode.
In the method for manufacturing a thin film transistor of the present invention, it is preferable that the conductive material is mainly composed of a conductive polymer material and / or a metal material.
Thereby, in the second step, the source electrode and the drain electrode using these as constituent materials can be easily formed by using a droplet discharge method.

In the thin film transistor manufacturing method of the present invention, the conductive polymer material is preferably composed mainly of PEDOT (polyethylenedioxythiophene).
These have excellent conductivity.
In the thin film transistor manufacturing method of the present invention, it is preferable that the metal material is mainly composed of at least one of Cu, Ni, Ag, or an alloy containing these.
These are those in which the characteristics are hardly deteriorated by the oxygen plasma treatment in the fourth step.

The thin film transistor of the present invention is manufactured by the method for manufacturing a thin film transistor of the present invention.
Thereby, a thin film transistor having excellent characteristics (switching characteristics) can be obtained.
The thin film transistor circuit of the present invention includes the thin film transistor of the present invention.
Thereby, a highly reliable thin film transistor circuit is obtained.

An electronic device according to the present invention includes the thin film transistor circuit according to the present invention.
Thereby, an electronic device with high reliability can be obtained.
An electronic apparatus according to the present invention includes the electronic device according to the present invention.
As a result, a highly reliable electronic device can be obtained.

Hereinafter, a thin film transistor manufacturing method, a thin film transistor, a thin film transistor circuit, an electronic device, and an electronic device according to preferred embodiments of the present invention will be described in detail.
<Thin Film Transistor and Manufacturing Method Thereof>
First, the thin film transistor of the present invention and the manufacturing method thereof will be described.
<< Configuration of Thin Film Transistor >>
First, an embodiment of the thin film transistor of the present invention will be described.

FIG. 1 is a longitudinal sectional view showing an embodiment of a thin film transistor. In the following description, the upper side in FIG. 1 is referred to as “upper” and the lower side is referred to as “lower”.
A thin film transistor 1 shown in FIG. 1 is provided on a substrate 2, and a source electrode 3 and a drain electrode 4, an organic semiconductor layer (organic layer) 5, a gate insulating layer 6, and a gate electrode 7 are arranged in this order. And are laminated from the substrate 2 side.

  Specifically, in the thin film transistor 1, a source electrode 3 and a drain electrode 4 are provided separately on a substrate 2, and an organic semiconductor layer 5 is provided so as to cover these electrodes 3 and 4. Further, a gate insulating layer 6 is provided on the organic semiconductor layer 5, and a gate electrode 7 is further provided thereon so as to overlap at least a region between the source electrode 3 and the drain electrode 4. The drain electrode 4 is connected to a pixel electrode (individual electrode) 41 described later.

In the thin film transistor 1, a region between the source electrode 3 and the drain electrode 4 in the organic semiconductor layer 5 is a channel region 51 in which carriers move. Hereinafter, in this channel region 51, the length in the carrier moving direction, that is, the distance between the source electrode 3 and the drain electrode 4 is the channel length L, and the length in the direction orthogonal to the channel length L direction is the channel width W. say.
Such a thin film transistor 1 is a thin film transistor having a structure in which the source electrode 3 and the drain electrode 4 are provided on the substrate 2 side with respect to the gate electrode 7 via the gate insulating layer 6, that is, a thin film transistor having a top gate structure.

Hereinafter, each part which comprises the thin-film transistor 1 is demonstrated sequentially.
The substrate 2 supports each layer (each part) constituting the thin film transistor 1. For the substrate 2, for example, a glass substrate, a plastic made of polyimide, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), polyethersulfone (PES), aromatic polyester (liquid crystal polymer), etc. A substrate (resin substrate), a quartz substrate, a silicon substrate, a gallium arsenide substrate, or the like can be used. When the thin film transistor 1 is given flexibility, a resin substrate is selected as the substrate 2.

An underlayer may be provided on the substrate 2. The underlayer is provided, for example, for the purpose of preventing the diffusion of ions from the surface of the substrate 2 and for the purpose of improving the adhesion (bondability) between the source electrode 3 and the drain electrode 4 and the substrate 2.
The constituent material of the underlayer is not particularly limited, but silicon oxide (SiO ₂ ), silicon nitride (SiN), polyimide, polyamide, a cross-linked insolubilized polymer, or the like is preferably used.

On the substrate 2, a source electrode 3 and a drain electrode 4 are juxtaposed at a predetermined distance along the channel length L direction.
The constituent material of the source electrode 3 and the drain electrode 4 may be any material as long as it has conductivity (conductive material), such as a conductive polymer material, a metal material, and a conductive oxidation material. And conductive materials such as carbonized materials can be used, and one or more of these can be used in combination.

Among these, it is preferable that the main component is a conductive polymer material and / or a metal material. Thereby, in the liquid material supply process [1-IV] to be described later, the source electrode 3 and the drain electrode 4 having these as constituent materials can be easily formed by using an ink jet method (droplet discharge method). it can.
Examples of the conductive polymer material include polyacetylene, polypyrrole, polythiophene such as polyethylenedioxythiophene (PEDOT), polyaniline, poly (p-phenylene), poly (p-phenylenevinylene), polyfluorene, polycarbazole, polysilane, or these Among these, it is preferable to use PEDOT (polyethylenedioxythiophene) as a main component. These have excellent conductivity, and have an advantage that the characteristics are not easily deteriorated due to the oxygen plasma treatment in the resist layer removing process described later.

Such a conductive polymer material is usually used in a state in which a polymer such as iron oxide, iodine, inorganic acid, organic acid, polystyrene sulfonic acid is doped and imparted with conductivity.
In addition, examples of the metal material include metal materials such as Pd, Pt, Au, W, Ta, Mo, Al, Cr, Ti, Cu, Ag, Ni, and alloys containing them. It is preferable to select as appropriate. For example, in the case of a p-channel thin film transistor in which holes move in the channel region, it is preferable to use as a main component at least one of Cu, Ni, Ag, or an alloy containing these having a relatively large work function. This ensures that holes move from the source electrode 4 to the channel region.

Furthermore, since these are chemically relatively stable, in the resist layer removal process described later, characteristics are hardly deteriorated by using various removal methods. The width expands.
In addition, ITO, FTO, ATO, SnO ₂ etc. are mentioned as a conductive oxide, Carbon black, a carbon nanotube, fullerene etc. are mentioned as a carbon-type material, These can be used.

The thickness (average) of the source electrode 3 and the drain electrode 4 is not particularly limited, but is preferably about 30 to 300 nm, and more preferably about 50 to 200 nm.
The distance (separation distance) between the source electrode 3 and the drain electrode 4, that is, the channel length L is preferably about 2 to 30 μm, and more preferably about 2 to 20 μm. The smaller the channel length L, the larger the ON current can be controlled, and the capacitance of the gate electrode can be further reduced. However, if the channel length L is smaller than the lower limit value, a high-precision photolithography technique is required due to electrode patterning, which may increase costs. Even when a small channel length L is achieved, the expected effect is often not reached due to the influence of contact resistance between the source electrode and the organic semiconductor. On the other hand, if the channel length L is made larger than the upper limit value, the value of the ON current becomes small and the characteristics of the thin film transistor 1 may be insufficient.

  The channel width W is preferably about 0.1 to 5 mm, and more preferably about 0.3 to 3 mm. When the channel width W is made smaller than the lower limit value, the value of the ON current becomes small and the characteristics of the thin film transistor 1 may be insufficient. On the other hand, when the channel width W is larger than the upper limit value, the thin film transistor 1 is increased in size, and there is a risk of increasing parasitic capacitance and increasing leakage current to the gate electrode 7 via the gate insulating layer 6.

The shape of the source electrode 3 and the drain electrode 4 is not limited to the shape described above. For example, both the source electrode 3 and the drain electrode 4 are comb-shaped and the teeth are meshed with each other. can do.
An organic semiconductor layer 5 is provided on the substrate 2 so as to cover the source electrode 3 and the drain electrode 4.

The organic semiconductor layer 5 is composed mainly of an organic semiconductor material (an organic material that exhibits semiconducting electrical conduction).
The organic semiconductor layer 5 is preferably oriented so as to be substantially parallel to the channel length L direction at least in the channel region 51. As a result, the carrier mobility in the channel region 51 is high, and as a result, the thin film transistor 1 has a higher operating speed.

  Examples of the organic semiconductor material include naphthalene, anthracene, tetracene, pentacene, hexacene, phthalocyanine, perylene, hydrazone, triphenylmethane, diphenylmethane, stilbene, arylvinyl, pyrazoline, triphenylamine, triarylamine, oligothiophene, phthalocyanine or Low molecular organic semiconductor materials such as these derivatives, poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polythiophene, polyhexylthiophene, poly (p-phenylenevinylene), polytinylenevinylene, polyarylamine, Pyreneformaldehyde resin, ethylcarbazole formaldehyde resin, fluorene-bithiophene copolymer, fluorene-arylamine copolymer or Examples thereof include polymeric organic semiconductor materials (conjugated polymer materials) such as derivatives, and one or more of these can be used in combination. It is preferable to use a material mainly composed of (conjugated polymer material). The conjugated polymer material has a particularly high carrier mobility due to its unique electron cloud spread.

A polymer organic semiconductor material can be formed by a simple method and can be oriented relatively easily.
Among these, fluorene and bithiophene, such as a fluorene-bithiophene copolymer, are used as high molecular organic semiconductor materials (conjugated polymer materials) because they are not easily oxidized in the air and are stable. It is particularly preferable to use a polymer containing at least one of a polymer containing arylamine such as a copolymer containing polyamine, a polyarylamine, a fluorene-arylamine copolymer, or a derivative thereof.

In addition, the organic semiconductor layer 5 composed mainly of a polymer organic semiconductor material can be reduced in thickness and weight, and has excellent flexibility. Therefore, the thin film transistor can be used as a switching element of a flexible display. Suitable for applications.
The thickness (average) of the organic semiconductor layer 5 is preferably about 0.1 to 1000 nm, more preferably about 1 to 500 nm, and further preferably about 10 to 100 nm.

Note that the organic semiconductor layer 5 is not limited to a structure provided so as to cover the source electrode 3 and the drain electrode 4, and is provided at least in a region (channel region 51) between the source electrode 3 and the drain electrode 4. It only has to be.
A gate insulating layer 6 is provided on the organic semiconductor layer 5.
This gate insulating layer 6 insulates the gate electrode 7 from the source electrode 3 and the drain electrode 4.

The gate insulating layer 6 is preferably composed mainly of an organic material (particularly an organic polymer material). The gate insulating layer 6 containing an organic polymer material as a main material can be easily formed and can improve adhesion to the organic semiconductor layer 5.
Examples of such organic polymer materials include polystyrene, polyimide, polyamideimide, polyvinylphenylene, polycarbonate (PC), acrylic resin such as polymethyl methacrylate (PMMA), and polytetrafluoroethylene (PTFE). Fluorine resin, phenolic resin such as polyvinylphenol or novolac resin, and olefinic resins such as polyethylene, polypropylene, polyisobutylene, polybutene, etc. are used, and one or more of these may be used in combination. it can.

  The thickness (average) of the gate insulating layer 6 is not particularly limited, but is preferably about 10 to 5000 nm, and more preferably about 100 to 1000 nm. By setting the thickness of the gate insulating layer 6 within the above range, the thin film transistor 1 is increased in size while the source electrode 3 and the drain electrode 4 are reliably insulated from the gate electrode 7 (particularly, the thickness is increased). ) Can be prevented.

Note that the gate insulating layer 6 is not limited to a single layer structure, and may have a multilayer structure.
In addition, as a constituent material of the gate insulating layer 6, for example, an inorganic insulating material such as SiO ₂ can be used. By applying a solution such as polysilicate, polysiloxane, or polysilazane and heating the coating film in the presence of oxygen or water vapor, SiO ₂ can be obtained from the solution material. In addition, after applying a metal alkoxide solution, an inorganic insulating material can be obtained (known as a sol-gel method) by heating it in an oxygen atmosphere.

A gate electrode 7 is provided on the gate insulating layer 6.
As a constituent material of the gate electrode 7, for example, Ag, Pd, Pt, Au, W, Ta, Mo, Al, Cr, Ti, Cu, Ni or a metal material such as an alloy containing these, ITO, FTO, ATO, Conductive oxides such as SnO ₂ , carbon materials such as carbon black, carbon nanotubes, fullerenes, polyacetylene, polypyrrole, polythiophene such as polyethylenedioxythiophene (PEDOT), polyaniline, poly (p-phenylene), poly (p- Phenylene vinylene), polyfluorene, polycarbazole, polysilane, or conductive polymer materials such as derivatives thereof, and the like, and one or more of them can be used in combination.

Such a conductive polymer material is usually used in a state in which a polymer such as iron oxide, iodine, inorganic acid, organic acid, polystyrene sulfonic acid is doped and imparted with conductivity.
The thickness (average) of the gate electrode 7 is not particularly limited, but is preferably about 0.1 to 5000 nm, more preferably about 1 to 5000 nm, and still more preferably about 10 to 5000 nm.

In the thin film transistor 1 as described above, the amount of current flowing between the source electrode 3 and the drain electrode 4 is controlled by changing the voltage applied to the gate electrode 7.
That is, in the OFF state in which no voltage is applied to the gate electrode 7, even if a voltage is applied between the source electrode 3 and the drain electrode 4, almost no carriers are present in the organic semiconductor layer 5, so that a very small current Only flows. On the other hand, in the ON state in which a voltage is applied to the gate electrode 7, charges are induced in the portion of the organic semiconductor layer 5 facing the gate insulating layer 6, and a carrier flow path is formed in the channel region 51. When a voltage is applied between the source electrode 3 and the drain electrode 4 in this state, a current flows through the channel region 51.

<Method for Manufacturing Thin Film Transistor>
Next, a method for manufacturing the thin film transistor 1 shown in FIG. 1 (an embodiment of the method for manufacturing a thin film transistor of the present invention) will be described.
2 and 3 are views (longitudinal sectional views) for explaining a method of manufacturing the thin film transistor shown in FIG. In the following description, the upper side in FIGS. 2 and 3 is referred to as “upper” and the lower side is referred to as “lower”.
The manufacturing method of the thin film transistor 1 includes [1] a source electrode and drain electrode formation step, [2] an organic semiconductor layer formation step, [3] a gate insulating layer formation step, and [4] a gate electrode formation step. ing. Hereinafter, each of these steps will be described sequentially.

[1] Source and Drain Electrode Formation Steps The present invention is characterized in the formation step (formation method) of the source electrode 3 and the drain electrode 4.
Here, in general, in forming a film using a resist layer, a resist layer having an opening in a region where the film is to be formed and being much thicker than the film thickness to be formed is used. And after forming the film | membrane with the target film thickness in the opening part of a resist layer, a resist layer is peeled.

However, when this method is used for the formation of the source and drain electrodes, when the resist layer is removed (peeled) using a stripping solution or the like, the formed electrodes are altered or deteriorated by the stripping solution or the like. As a result, there is a problem that the characteristics of the thin film transistor are deteriorated.
In contrast, in the present invention, a resist layer 8 thinner than the thickness of the electrodes 3 and 4 to be formed is formed, and the source electrode 3 and the drain electrode 4 are formed using the resist layer 8. For this reason, when removing the resist layer 8, the electrodes 3 and 4 can be prevented or suppressed from being deteriorated or deteriorated. As a result, the obtained thin film transistor 1 has excellent characteristics.

  Specifically, this step [1] has an opening 82 having a shape corresponding to the source electrode 3 and the drain electrode 4, and is thinner than the thickness of the source electrode 3 and the drain electrode 4 to be formed. In the resist layer forming step for forming the resist layer 8, in the opening portion 82, in the opening portion 82, in the opening portion 82, in the opening portion 82, in the opening portion 82, in the opening portion 82 A liquid material supplying step of supplying the liquid material 9 containing the conductive material and / or its precursor and the aqueous solvent so as to be thicker than the thickness of the resist layer 8; and removing the aqueous solvent from the liquid material 9. The electrode forming step for obtaining the source electrode 3 and the drain electrode 4 and the resist layer removing step for removing the resist layer 8 are included. Hereinafter, each of these steps will be described sequentially.

[1-I] Resist Layer Forming Step First, a substrate 2 as shown in FIG. 2A is prepared, and this substrate 2 is washed, for example, with water (pure water or the like), an organic solvent, or the like alone or in combination as appropriate. To do.
Next, pretreatment for improving the adhesion between the substrate 2 and the resist layer 8 is performed on the upper surface of the substrate 2.

This pretreatment includes silazanes such as hexamethyldisilazane (HMDS), chlorosilanes such as dimethylchlorosilane and trimethylchlorosilane, alkoxysilanes such as dimethyldimethoxysilane and hexyltrimethoxysilane, or titanate cups. Examples include primer treatment using a ring agent or the like.
Among these, it is preferable to perform this pretreatment using hexamethyldisilazane. Thereby, the adhesiveness of the board | substrate 2 and the resist layer 8 can be improved more reliably.
This pretreatment can be omitted as necessary.

Next, a photoresist is supplied onto the substrate 2 to form a film 8 ′ (see FIG. 2B).
The photoresist supplied onto the substrate 2 is a negative photoresist that is exposed to light (exposure) is cured and a region other than the exposed region is dissolved and removed by development, and exposed. Any positive type photoresist in which the region is dissolved and removed by development may be used.

Negative photoresists include rosin-dichromate, polyvinyl alcohol (PVA) -bichromate, shellac-bichromate, casein-dichromate, PVA-diazo, acrylic photoresist, etc. And water-soluble photoresists such as oil-soluble photoresists such as polyvinyl cinnamate, cyclized rubber-azide, polyvinyl cinnamylidene acetate, and polycinnamic acid β-vinyloxyethyl ester.
Examples of positive photoresists include oil-soluble photoresists such as o-naphthoquinonediazide.

Any method may be used for supplying the photoresist onto the substrate 2, but a coating method is preferably used.
Examples of coating methods include spin coating, casting, micro gravure coating, gravure coating, bar coating, roll coating, wire bar coating, dip coating, spray coating, screen printing, and flexographic printing. Method, offset printing method, ink jet method (droplet discharge method), micro contact printing method, and the like, and one or more of them can be used in combination.

Moreover, you may make it perform prebaking process which heats with respect to obtained film 8 '. Thereby, film 8 'can be solidified reliably.
The temperature of this treatment (heat treatment) is preferably about 40 to 200 ° C, more preferably about 80 to 150 ° C.
The time for this treatment is preferably about 2 to 20 minutes, more preferably about 5 to 10 minutes.

Next, the coating 8 ′ is exposed and developed through a photomask to form a resist layer 8 having an opening 82 in a region where the source electrode 3 and the drain electrode 4 are to be formed (see FIG. 2C). .
Here, the thickness Y of the resist layer 8 is set to be thinner than the thickness X of the source electrode 3 and the drain electrode 4 formed in an electrode formation step [1-V] described later. Thereby, in the resist layer removing step [1-VI], the resist layer 8 can be removed in a short time. Thereby, alteration and deterioration of the source electrode 3 and the drain electrode 4 due to the process of removing the resist layer 8 can be prevented or suppressed.

The thickness Y of the resist layer 8 may be any thickness as long as it is thinner than the thickness X of the source electrode 3 and drain electrode 4 to be formed. It is preferable to satisfy the relationship of 2 to 10, and it is more preferable to satisfy the relationship of X / Y of 4 to 8. By satisfying such a relationship, it is possible to more reliably prevent or suppress the alteration / deterioration of the source electrode 3 and the drain electrode 4 due to the process of removing the resist layer 8.
When the thickness of the resist layer 8 is Y [nm], the thickness Y is preferably about 5 to 50 nm, and more preferably about 5 to 20 nm.

[1-II] Hydrophilic Treatment Step Next, as shown in FIG. 2D, for example, a region corresponding to the resist layer 8 is masked and a hydrophilic treatment is performed in the opening 82 of the resist layer 8.
As the hydrophilic treatment, for example, a method of irradiating the inside of the opening 82 with ultraviolet rays and / or infrared rays in an oxygen-containing atmosphere and an oxygen plasma treatment method of irradiating oxygen plasma can be used. It is preferable to use an oxygen plasma treatment method.

In this oxygen plasma treatment method, a gas containing oxygen is introduced into a discharge region for generating oxygen plasma, and the oxygen plasma generated in this discharge region is applied to the side surface of the resist layer 8 in the opening 82 and / or the substrate 2. By making it enter, hydrophilicity is provided.
According to this processing method, hydrophilicity can be easily and reliably imparted to the opening 82.

As the gas containing oxygen gas, pure oxygen gas is typically used, but a mixed gas of oxygen gas and fluorocarbon gas (for example, tetrafluoromethane gas) is preferably used. As a result, the time during which the oxygen plasma is maintained becomes long, and the oxygen plasma can reach the opening 82 in the state of oxygen plasma.
The oxygen gas concentration (content ratio) in this mixed gas is preferably about 60 to 90 vol%, more preferably about 65 to 80 vol%.

By setting the concentration of oxygen gas within the above range, the oxygen plasma can reach the opening 82 more efficiently.
The flow rate of the gas containing oxygen gas is preferably about 10 to 500 sccm, and more preferably about 50 to 400 sccm.
Also, RF power is preferably in the range of about 0.005~0.2W / cm ^2, more preferably about 0.05~0.1W / cm ^2.

Next, the atmospheric temperature during the oxygen plasma irradiation is preferably about 0 to 100 ° C., more preferably about 20 to 50 ° C.
Furthermore, the oxygen plasma irradiation time is preferably about 1 to 120 seconds, and more preferably about 10 to 60 seconds.
In addition, it is preferable that the pressure in this case is under atmospheric pressure. Thereby, use of a chamber, a decompression means, etc. can be made unnecessary, and it can process at low energy and low cost.

[1-III] Water Repellent Treatment Step Next, as shown in FIG. 2 (e), for example, a region corresponding to the opening 82 is masked to form the upper surface of the resist layer 8 (the surface opposite to the substrate). Apply water repellent treatment.
As the water repellent treatment, for example, a method of forming a water repellent film by supplying a material having water repellency to the upper surface of the resist layer 8, a fluorine plasma treatment method of irradiating fluorine plasma, or the like is used. Among these, it is preferable to use a fluorine plasma treatment method.

In this fluorine plasma processing method, a fluorine-containing gas is introduced into a discharge region for generating fluorine plasma, and the fluorine plasma generated in this discharge region is incident on the upper surface of the resist layer 8 so that the fluorine plasma is incident. Water repellency is imparted to the formed region.
According to such a processing method, the upper surface of the resist layer 8 can be uniformly fluorinated almost entirely, that is, the water repellency can be imparted uniformly (evenly) to the upper surface of the resist layer 8.

Examples of the gas species containing a fluorine atom include tetrafluoromethane (CF ₄ ), tetrafluoroethylene (C ₂ F ₄ ), hexafluoropropylene (C ₃ F ₆ ), and octafluorobutylene (C _4). F ₈ ) and the like, and among these, those mainly containing tetrafluoromethane are preferred.
The flow rate of the gas containing fluorine atoms is preferably about 10 to 500 sccm, and more preferably about 50 to 400 sccm.
The RF power is preferably about 0.005 to 0.2 W / cm ² , and more preferably about 0.05 to 0.1 W / cm ² .

Next, the atmospheric temperature during the fluorine plasma irradiation is preferably about 0 to 100 ° C, and more preferably about 20 to 50 ° C.
Furthermore, the irradiation time of this fluorine plasma irradiation is preferably about 1 to 60 seconds, and more preferably about 10 to 30 seconds. When this irradiation time is shorter than the said range, there exists a possibility that water repellency cannot fully be provided to the resist layer 8. FIG. If the irradiation time is longer than the above range, fluorine may enter the opening of the resist layer 8 and the opening may be inclined from hydrophilic to water-repellent.
In addition, it is preferable that the pressure in this case is under atmospheric pressure. Thereby, use of a chamber, a decompression means, etc. can be made unnecessary, and it can process at low energy and low cost.

By performing such a hydrophilic treatment step [1-II] and a water repellent treatment step [1-III] in the opening 82 and on the upper surface of the resist layer 8, the water repellency on the upper surface of the resist layer 8 is made open. The water repellency can be higher. Thereby, it is possible to prevent the liquid material supplied into the opening 82 from diffusing (transferring) to the upper surface of the resist layer 8 in the liquid material supplying step described later.
In addition, when the substrate 2 itself has hydrophilicity and when the resist layer 8 itself has water repellency, one or both of the steps [1-II] and [1-III] are omitted. be able to.

[1-IV] Liquid Material Supply Step Next, as shown in FIG. 3 (f), the source electrode 3 and the drain electrode 4 to be formed in the opening 82 of the substrate 2 subjected to the above-described processing. In response to this, a predetermined amount of the liquid material 9 is supplied. The liquid material 9 is supplied to be thicker than the resist layer 8.
Here, in the water repellent and hydrophilic treatment steps described above, the upper surface of the resist layer 8 is subjected to water repellent treatment, and the opening 82 is subjected to hydrophilic treatment.

For this reason, when the liquid material 9 is supplied into the opening 82, since the hydrophilic treatment is performed in the opening 82, the liquid material 9 spreads uniformly in the opening 82.
Further, even when the thickness of the liquid material 9 is supplied so as to be thicker than the thickness of the resist layer 8, the liquid material 9 is provided on the top surface of the resist layer 8. Transition to the top surface is prevented. Thereby, the source electrode 3 and the drain electrode 4 of the target shape can be formed with high accuracy. As a result, the obtained thin film transistor 1 has excellent characteristics.

The difference in the degree of water repellency between the upper surface of the resist layer 8 and the inside of the opening 82 can be expressed by various indicators, but can be preferably expressed by using a contact angle.
Specifically, when the contact angle of the liquid material 9 with respect to the upper surface of the resist layer 8 is A [°] and the contact angle of the liquid material 9 with respect to the opening 82 is B [°], A−B ≧ 15. It is preferable to satisfy the relationship, and it is more preferable to satisfy the relationship of AB ≧ 30. By satisfying such a relationship, the liquid material 9 supplied into the opening 82 so as to be thicker than the thickness of the resist layer 8 is more reliably diffused (transferred) to the upper surface of the resist layer 8. Can be prevented.

  As a method of supplying the liquid material 9 into the opening 82, the same coating method as that described in the resist layer forming step [1-I] can be used. Among these, the inkjet method ( It is preferable to use a droplet discharge method. According to the ink jet method, the liquid material 9 can be reliably supplied into the opening 82 and the diffusion into the resist layer 8 can be more reliably prevented.

Hereinafter, a method of forming the source electrode 3 and the drain electrode 4 using an ink jet method will be described.
In the ink jet method, a liquid material 9 (hereinafter referred to as “ink”) containing a conductive material and / or a precursor thereof and an aqueous solvent is patterned by discharging droplets from nozzles of a droplet discharge head. .

Here, the viscosity (normal temperature) of the ink is not particularly limited, but is usually preferably about 3 to 10 cps, and more preferably about 4 to 8 cps. By setting the viscosity of the ink within such a range, it is possible to more stably discharge droplets from the nozzles.
Also, the amount (average) of one drop of ink is not particularly limited, but is usually preferably about 0.1 to 40 pL, and more preferably about 1 to 30 pL. By setting the amount (average) of one droplet to such a range, a more precise shape can be formed.

For example, the following <A> to <D> are used as the ink.
<A> When the source electrode 3 and the drain electrode 4 are made of a conductive polymer material, a solution or dispersion liquid in which the conductive polymer material is dissolved or dispersed in an aqueous solvent is used as the ink.
<B> When the source electrode 3 and the drain electrode 4 are made of an inorganic material (for example, metal material), a dispersion liquid (colloid) in which inorganic material particles (for example, metal particles) are dispersed in an aqueous solvent is used as the ink. it can.
In this case, the content of the inorganic material particles in the ink is not particularly limited, but is preferably about 1 to 40 wt%, and more preferably about 10 to 30 wt%.

The average particle diameter of the inorganic material particles used is not particularly limited, but is preferably about 1 to 100 nm, and more preferably about 2 to 30 nm.
Moreover, it is preferable to use what was coat | covered with the aggregation inhibitor (dispersing agent) for preventing aggregation at normal temperature as an inorganic material particle. Examples of the aggregation inhibitor include a compound having a group containing a nitrogen atom such as an alkylamine, a compound having a group containing an oxygen atom such as alkanediol, a group containing a sulfur atom such as alkylthiol and alkanedithiol. And the like. As the alkanediol, propylene glycol, trimethylene glycol, ethylene glycol and butanediol are suitable.

  In this case, a removing agent capable of removing the aggregation inhibitor is added to the ink by a predetermined treatment (for example, heating or the like). Examples of the removing agent include linear or branched saturated carboxylic acids having 1 to 10 carbon atoms such as formic acid, acetic acid, propionic acid, butanoic acid, hexanoic acid and octylic acid, acrylic acid, methacrylic acid and croton. Various carboxylic acids such as acid, cinnamic acid, benzoic acid, unsaturated carboxylic acid such as sorbic acid, oxalic acid, malonic acid, sebacic acid, maleic acid, fumaric acid, dibasic acid such as itaconic acid, etc. Organic acids such as various phosphoric acids and various sulfonic acids in which the carboxyl group of the carboxylic acid is substituted with a phosphoric acid group or a sulfonyl group, or organic acid esters thereof, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, Benzophenone tetracarboxylic anhydride, ethylene glycol bis (anhydrotrimellitate), glycerol tris (anhydrotrimethylate) Aromatic anhydride, maleic anhydride, succinic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methyl nadic anhydride, alkenyl succinic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride Examples thereof include aliphatic acid anhydrides such as acid, cyclic aliphatic acid anhydrides such as methylcyclohexene tetracarboxylic acid anhydride, polyadipic acid anhydrides, polyazeline acid anhydrides, polysebacic acid anhydrides, and the like.

Also, in the ink, phenol resin, epoxy resin, unsaturated polyester resin, vinyl ester resin, diallyl phthalate resin, oligoester acrylate resin, xylene resin, bismaleimide triazine resin, furan resin, urea resin, polyurethane resin, melamine resin A precursor of various thermosetting resins such as silicon resin may be added (mixed).
The viscosity of the ink can be adjusted, for example, by appropriately setting the content of the inorganic material particles, the type and composition of the dispersion medium, the presence / absence and type of additives, and the like.

<C> In the case where the source electrode 3 and the drain electrode 4 are made of a metal material, as the ink, the metal oxide particles made of a metal oxide that becomes a metal material by being reduced and the reducing agent are water-based. A solution or dispersion dissolved or dispersed in a solvent can be used.
In this case, the content of the metal oxide particles in the ink is not particularly limited, but is preferably about 1 to 40 wt%, and more preferably about 10 to 30 wt%.

Moreover, the average particle diameter of the metal oxide particles to be used is not particularly limited, but is preferably 100 nm or less, and more preferably 30 nm or less.
Examples of the reducing agent include ascorbic acid, hydrogen sulfide, oxalic acid, carbon monoxide and the like.
The viscosity of the ink can be adjusted, for example, by appropriately setting the content of metal oxide particles, the type and composition of the dispersion medium, and the like.

<D> When the source electrode 3 and the drain electrode 4 are made of a metal oxide, a solution or dispersion obtained by dissolving or dispersing a metal oxide precursor in an aqueous solvent can be used as the ink.
Examples of the metal oxide precursor used include organic metal compounds such as metal alkoxides, acetic acid or metal salts of acetic acid derivatives, metal chlorides, metal sulfides, inorganic metal compounds such as metal cyanides, and the like. One or more of these can be used in combination.
The concentration (content) of the metal oxide precursor in the ink is not particularly limited, but is preferably about 1 to 50 wt%, and more preferably about 10 to 30 wt%.

The viscosity of the ink can be adjusted, for example, by appropriately setting the concentration of the metal oxide precursor, the type and composition of the solvent, and the like.
In the ink as described above, examples of the aqueous solvent (relatively high solvent) include water, monohydric alcohols such as methanol, ethanol and isopropanol, polyhydric alcohols such as ethylene glycol and glycerin, and acetone. Such ketones, esters such as ethyl acetate and the like can be mentioned, and these can be used alone or as a mixed solution.

[1-V] Electrode Formation Step Next, the aqueous solvent is removed from the liquid material 9 supplied to the opening 82 to obtain the source electrode 3 and the drain electrode 4 (see FIG. 3G).
The temperature at the time of removing the solvent (removal temperature) is not particularly limited and varies slightly depending on the constituent material of the aqueous solvent, but is preferably about 20 to 200 ° C, more preferably about 50 to 100 ° C. preferable. Thereby, the aqueous solvent contained in the liquid material 9 can be reliably removed.

Next, the time for removing the solvent is not particularly limited, and is slightly different depending on the removal temperature, but is preferably about 5 to 100 min, and more preferably about 10 to 50 min.
Further, a heating means may be used in accordance with the removal temperature. For example, the source electrode 3 and the drain electrode 4 can be obtained by performing heating, irradiation with infrared rays, application of ultrasonic waves, or the like.

[1-VI] Resist Layer Removal Step Next, the resist layer 8 is removed from the substrate 2.
The method for removing the resist layer 8 may be appropriately selected according to the type of the resist layer 8. For example, ashing such as plasma treatment or ozone treatment, ultraviolet irradiation, Ne-He laser, Ar laser, CO ₂ laser, It can be carried out by irradiation with various lasers such as ruby laser, semiconductor laser, YAG laser, glass laser, YVO ₄ laser, excimer laser, contact with a solvent capable of dissolving or decomposing the resist layer 8 (for example, immersion).

Among these, it is particularly preferable to use plasma treatment. According to the plasma treatment, the resist layer 8 can be easily removed while suppressing deterioration and deterioration of the source electrode 3 and the drain electrode 4.
As the plasma treatment, for example, oxygen plasma treatment, fluorine plasma treatment, argon plasma treatment, or the like can be used. Among these, oxygen plasma treatment is preferably used. Thus, the resist layer 8 can be easily removed while more reliably suppressing the deterioration and deterioration of the source electrode 3 and the drain electrode 4.

  When the constituent material of the source electrode 3 and the drain electrode 4 contains Cu and Ni, the oxygen plasma treatment oxidizes Cu and Ni present on the surfaces of the electrodes 3 and 4, As a result, a secondary effect such as improvement in characteristics (for example, an increase in work function) can be obtained. Thereby, when the P-channel type thin film transistor 1 is constructed, the characteristics can be improved.

  When oxygen plasma treatment is used, the resist layer 8 is removed by irradiating oxygen plasma onto the substrate 2 on which the resist layer 8, the source electrode 3 and the drain electrode 4 are formed, as shown in FIG. (See FIG. 3 (i)).

At this time, in the present invention, since the resist layer 8 is formed to be thinner than the source electrode 3 and the drain electrode 4, the resist layer 8 can be removed in a short time. For this reason, when the resist layer 8 is removed, alteration / deterioration of the source electrode 3 and the drain electrode 4 can be suitably prevented or suppressed.
The flow rate of oxygen gas is preferably about 10 to 200 sccm, and more preferably about 50 to 150 sccm.
Also, RF power is preferably in the range of about 0.005~0.2W / cm ^2, more preferably about 0.05~0.1W / cm ^2.

Next, the atmospheric temperature during the oxygen plasma irradiation is preferably about 0 to 100 ° C., more preferably about 20 to 50 ° C.
Furthermore, the oxygen plasma irradiation time is preferably about 1 to 300 seconds, and more preferably about 10 to 150 seconds.
By setting the condition of the oxygen plasma treatment within the above range, the resist layer 8 can be more reliably removed, and the alteration and deterioration of the source electrode 3 and the drain electrode 4 can be suitably prevented or suppressed. As a result, the thin film transistor 1 having excellent characteristics can be obtained.

[2] Organic Semiconductor Layer Forming Step Next, as shown in FIG. 3 (j), the organic layer is formed so as to cover the source electrode 3 and the drain electrode 4 on the substrate 2 on which the source electrode 3 and the drain electrode 4 are formed. The semiconductor layer 5 is formed.
At this time, a channel region 51 is formed between the source electrode 3 and the drain electrode 4 (region corresponding to the gate electrode 7).

The organic semiconductor layer 5 is necessary after applying (supplying) a solution containing an organic polymer material or a precursor thereof on the substrate 2 so as to cover the source electrode 3 and the drain electrode 4 by using, for example, a coating method. Accordingly, the coating film can be formed by post-treatment (for example, heating, infrared irradiation, application of ultrasonic waves, etc.).
Here, as the coating method, the same method as that for forming the source electrode and the drain electrode described above can be used, but among them, the spin coating method is particularly preferable. According to the spin coating method, the organic semiconductor layer 5 can be formed easily and inexpensively.

  The formation region of the organic semiconductor layer 5 is not limited to the illustrated configuration, and the organic semiconductor layer 5 may be formed only in a region (channel region 51) between the source electrode 3 and the drain electrode 4. Accordingly, when a plurality of thin film transistors 1 (elements) are arranged in parallel on the same substrate, the leakage current and crosstalk between the elements are suppressed by forming the organic semiconductor layer 5 of each element independently. Can do. Moreover, the usage-amount of organic-semiconductor material can be reduced and manufacturing cost can also be reduced. When the organic semiconductor layer 5 is formed only in the channel region 51, the ink jet method (droplet discharge method) is particularly suitable in that it can be performed without contact. Further, the necessary resolution is 5 to 100 μm, which is compatible with the resolution of the ink jet method.

  In this case, examples of the solvent for dissolving the organic semiconductor material include inorganic solvents such as nitric acid, sulfuric acid, ammonia, hydrogen peroxide, water, carbon disulfide, carbon tetrachloride, and ethylene carbonate, methyl ethyl ketone (MEK), acetone, Ketone solvents such as diethyl ketone, methyl isobutyl ketone (MIBK), methyl isopropyl ketone (MIPK), cyclohexanone, alcohol solvents such as methanol, ethanol, isopropanol, ethylene glycol, diethylene glycol (DEG), glycerin, diethyl ether, diisopropyl ether 1,2-dimethoxyethane (DME), 1,4-dioxane, tetrahydrofuran (THF), tetrahydropyran (THP), anisole, diethylene glycol dimethyl ether (diglyme), die Ether solvents such as lenglycol ethyl ether (carbitol), cellosolv solvents such as methyl cellosolve, ethyl cellosolve, phenyl cellosolve, aliphatic hydrocarbon solvents such as hexane, pentane, heptane, cyclohexane, toluene, xylene, benzene, etc. Aromatic hydrocarbon solvents, aromatic heterocyclic compounds such as pyridine, pyrazine, furan, pyrrole, thiophene, methylpyrrolidone, N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMA), etc. Amide solvents, halogen compound solvents such as dichloromethane, chloroform, 1,2-dichloroethane, ester solvents such as ethyl acetate, methyl acetate, ethyl formate, sulfur compound solvents such as dimethyl sulfoxide (DMSO), sulfolane, acetonite Le, propionitrile, nitrile solvents, formic acid such as acrylonitrile, acetic acid, trichloroacetic acid, various organic solvents such as an organic acid solvents such as trifluoroacetic acid, or may be a mixed solvent containing these.

Since organic semiconductor materials contain conjugated systems such as aromatic hydrocarbon groups and heterocyclic groups, they are generally easily soluble in aromatic hydrocarbon solvents. Toluene, xylene, trimethylbenzene, tetramethylbenzene, cyclohexylbenzene and the like are particularly suitable solvents.
In addition, when using a low molecular thing as an organic-semiconductor material, the organic-semiconductor layer 5 can also be formed using a vacuum evaporation method etc., for example.

[3] Gate Insulating Layer Forming Step Next, as shown in FIG. 4 (k), the gate insulating layer 6 is formed on the organic semiconductor layer 5.
The gate insulating layer 6 can be formed in the same manner as the organic semiconductor layer 5, for example.
When using the coating method, when the organic semiconductor layer 5 is made of a soluble organic semiconductor material, a solvent for the insulating material is selected so that the organic semiconductor layer 5 does not swell or dissolve. There is a need. As described above, since the organic semiconductor material is easily dissolved in the aromatic hydrocarbon solvent, it is more desirable to avoid this when applying the insulating material. That is, it is desirable to use an aqueous solvent, an alcohol solvent, a ketone solvent, an ether solvent, an ester solvent, an aliphatic hydrocarbon solvent, or a fluorine solvent.

[4] Step of Forming Gate Electrode Next, as shown in FIG. 4L, the gate electrode 7 is formed on the gate insulating layer 6.
Specifically, the gate electrode 7 is applied as necessary after applying (supplying) a liquid material (electrode material) or a solution containing a precursor thereof onto the gate insulating layer 6 using, for example, a coating method. The coating film can be formed by subjecting it to a post-treatment (for example, heating, infrared irradiation, application of ultrasonic waves, etc.).

As a coating method, a method similar to the above can be used, but it is particularly preferable to use an inkjet method (droplet discharge method). According to the inkjet method, the gate electrode 7 having a predetermined shape can be easily and reliably formed.
When the gate electrode 7 is formed using an ink jet method, the same method as that used when forming the source electrode 3 and the drain electrode 4 can be used.
However, the solvent of the ink is not limited to the aqueous solvent, and various solvents can be used.

  Specifically, for example, inorganic substances such as nitric acid, sulfuric acid, ammonia, hydrogen peroxide, water, carbon disulfide, carbon tetrachloride, ethylene carbonate, methyl ethyl ketone (MEK), acetone, diethyl ketone, methyl isobutyl ketone (MIBK) , Ketones such as methyl isopropyl ketone (MIPK), cyclohexanone, monohydric alcohols such as methanol, ethanol, isopropanol, polyhydric alcohols such as ethylene glycol, diethylene glycol (DEG), glycerin, diethyl ether, diisopropyl ether, 1, 2 -Dimethoxyethane (DME), 1,4-dioxane, tetrahydrofuran (THF), tetrahydropyran (THP), anisole, diethylene glycol dimethyl ether (diglyme), diethylene glycol ether Ethers such as ruether (carbitol), cellosolves such as methyl cellosolve, ethyl cellosolve, phenyl cellosolve, aliphatic hydrocarbons such as hexane, pentane, heptane and cyclohexane, aromatic hydrocarbons such as toluene, xylene and benzene , Aromatic heterocyclic compounds such as pyridine, pyrazine, furan, pyrrole, thiophene and methylpyrrolidone, amides such as N, N-dimethylformamide (DMF) and N, N-dimethylacetamide (DMA), dichloromethane, chloroform, Halogen compounds such as 1,2-dichloroethane, esters such as ethyl acetate, methyl acetate and ethyl formate, sulfur compounds such as dimethyl sulfoxide (DMSO) and sulfolane, and nitriles such as acetonitrile, propionitrile and acrylonitrile Formic acid, acetic acid, trichloroacetic acid, various organic materials such as organic acids such as trifluoroacetic acid, or mixtures containing them.

Through the above steps, the thin film transistor 1 shown in FIG. 1 is obtained.
In such a manufacturing method, as a method of forming the source electrode 3 and the drain electrode 4, a liquid material 9 containing a material for forming these electrodes 3 and 4 is formed on the substrate 2 by an inkjet method (droplet discharge). Method) is used. According to this method, the thin film transistor 1 can be manufactured at a low cost by a simple method without requiring a large-scale apparatus as compared with the case of using a vacuum process or the like.

  In addition, a supply region (opening 82) of the liquid material 9 for forming the source electrode 3 and the drain electrode 4 is formed by the resist layer 8. Thereby, even if this application area | region is a comparatively fine shape, it forms with dimensional accuracy. As a result, the source electrode 3 and the drain electrode 4 can be formed with high dimensional accuracy, and an accurate channel length L and channel width W can be obtained.

Further, since the thickness of the resist layer 8 is thinner than the thickness of the source electrode 3 and the drain electrode 4, the process for removing the resist layer 8 can be completed in a short time. Thereby, it is possible to suitably prevent or suppress the deterioration and deterioration of the source electrode 3 and the drain electrode 4 due to the treatment for removing the resist layer 8.
Further, in this manufacturing method, after the source electrode 3 and the drain electrode 4 are formed, the resist layer 8 is removed, so that adverse effects due to the resist layer 8 remaining between the source electrode 3 and the drain electrode 4 can be avoided. Can do.
Therefore, the thin film transistor 1 having excellent characteristics can be manufactured with high manufacturing efficiency.

<Electronic device>
Next, an electrophoretic display device will be described as an example of an electronic device in which an active matrix device including the thin film transistor 1 as described above is incorporated.
FIG. 5 is a longitudinal sectional view showing an embodiment when the electronic device of the present invention is applied to an electrophoretic display device, and FIG. 6 is a block diagram showing a configuration of an active matrix device included in the electrophoretic display device shown in FIG. It is.

An electrophoretic display device 20 shown in FIG. 5 includes an active matrix device (a thin film transistor circuit of the present invention) 30 provided on a substrate 50 and an electrophoretic display unit 40 electrically connected to the active matrix device 30. It is configured.
As shown in FIG. 6, the active matrix device 30 includes a plurality of data lines 31 orthogonal to each other, a plurality of scanning lines 32, and a thin film transistor 1 provided near each intersection of the data lines 31 and the scanning lines 32. And have.

The gate electrode 7 of the thin film transistor 1 is connected to the scanning line 32, the source electrode 3 is connected to the data line 31, and the drain electrode 4 is connected to a pixel electrode (individual electrode) 41 described later.
As shown in FIG. 5, the electrophoretic display unit 40 includes a pixel electrode 41, a microcapsule 42, a transparent electrode (common electrode) 43, and a transparent substrate 44 that are sequentially stacked on a substrate 50. Yes.

The microcapsule 42 is fixed between the pixel electrode 41 and the transparent electrode 43 by a binder material 45.
The pixel electrodes 41 are divided so as to be regularly arranged in a matrix, that is, vertically and horizontally.
In each capsule 42, an electrophoretic dispersion liquid 420 including a plurality of types of electrophoretic particles having different characteristics, and in this embodiment, two types of electrophoretic particles 421 and 422 having different charges and colors (hue) are encapsulated. Has been.

In the electrophoretic display device 20, when a selection signal (selection voltage) is supplied to one or a plurality of scanning lines 32, the thin film transistor connected to the scanning line 32 to which the selection signal (selection voltage) is supplied. 1 is turned on.
Thereby, the data line 31 and the pixel electrode 41 connected to the thin film transistor 1 are substantially conducted. At this time, if desired data (voltage) is supplied to the data line 31, this data (voltage) is supplied to the pixel electrode 41.

As a result, an electric field is generated between the pixel electrode 41 and the transparent electrode 43, and the electrophoretic particles 421 and 422 are either one of the electrophoretic particles 421 and 422 depending on the direction and strength of the electric field and the characteristics of the electrophoretic particles 421 and 422. Electrophoresis in the direction of the electrode.
On the other hand, when the supply of the selection signal (selection voltage) to the scanning line 32 is stopped from this state, the thin film transistor 1 is turned off, and the data line 31 and the pixel electrode 41 connected to the thin film transistor 1 are in a non-conductive state. Become.

Therefore, by supplying and stopping the selection signal to the scanning line 32 or by appropriately combining the supply and stop of data to the data line 31, the display surface side (transparent substrate 44 side) of the electrophoretic display device 20 is performed. A desired image (information) can be displayed.
In particular, in the electrophoretic display device 20 of the present embodiment, it is possible to display a multi-tone image by making the colors of the electrophoretic particles 421 and 422 different.

In addition, since the electrophoretic display device 20 of the present embodiment has the active matrix device 30, the thin film transistor 1 connected to the specific scanning line 32 can be selectively turned on / off. And the circuit operation can be speeded up, so that a high quality image (information) can be obtained.
In addition, since the electrophoretic display device 20 of the present embodiment operates with a low driving voltage, power saving can be achieved.
Note that the electronic device of the present invention is not limited to the application to the electrophoretic display device 20, and can be applied to a liquid crystal display device, an organic or inorganic EL display device, and the like.

<Electronic equipment>
Such an electrophoretic display device 20 can be incorporated into various electronic devices. Hereinafter, the electronic apparatus of the present invention including the electrophoretic display device 20 will be described.
<< Electronic Paper >>
First, an embodiment when the electronic apparatus of the present invention is applied to electronic paper will be described.
FIG. 7 is a perspective view showing an embodiment when the electronic apparatus of the present invention is applied to electronic paper.
An electronic paper 600 shown in this figure includes a main body 601 composed of a rewritable sheet having the same texture and flexibility as paper, and a display unit 602.
In such an electronic paper 600, the display unit 602 includes the electrophoretic display device 20 as described above.

<< Display >>
Next, an embodiment when the electronic apparatus of the present invention is applied to a display will be described.
8A and 8B are diagrams showing an embodiment in which the electronic apparatus of the present invention is applied to a display. FIG. 8A is a cross-sectional view, and FIG. 8B is a plan view.
A display 800 shown in this figure includes a main body 801 and an electronic paper 600 that is detachably attached to the main body 801. The electronic paper 600 has the same configuration as described above, that is, the configuration shown in FIG.

  The main body 801 has an insertion port 805 into which the electronic paper 600 can be inserted on the side (right side in the drawing), and two pairs of conveying rollers 802a and 802b are provided inside. When the electronic paper 600 is inserted into the main body 801 through the insertion port 805, the electronic paper 600 is installed in the main body 801 in a state of being sandwiched between the pair of conveyance rollers 802a and 802b.

  Further, a rectangular hole 803 is formed on the display surface side of the main body 801 (the front side in the drawing (b) below), and a transparent glass plate 804 is fitted into the hole 803. Thereby, the electronic paper 600 installed in the main body 801 can be viewed from the outside of the main body 801. That is, in the display 800, the display surface is configured by visually recognizing the electronic paper 600 installed in the main body 801 on the transparent glass plate 804.

In addition, a terminal portion 806 is provided at the leading end portion (left side in the drawing) of the electronic paper 600, and the terminal portion with the electronic paper 600 installed on the main body portion 801 is provided inside the main body portion 801. A socket 807 to which 806 is connected is provided. A controller 808 and an operation unit 809 are electrically connected to the socket 807.
In such a display 800, the electronic paper 600 is detachably installed on the main body 801, and can be carried and used while being detached from the main body 801.

In such a display 800, the electronic paper 600 is configured by the electrophoretic display device 20 as described above.
Note that the electronic apparatus of the present invention is not limited to the application to the above, and for example, a television, a viewfinder type, a monitor direct view type video tape recorder, a car navigation device, a pager, an electronic notebook, a calculator, an electronic Examples include newspapers, word processors, personal computers, workstations, videophones, POS terminals, and devices equipped with touch panels. The electrophoretic display device 20 can be applied to the display units of these various electronic devices. is there.

Although the thin film transistor manufacturing method, thin film transistor, electronic device, and electronic apparatus of the present invention have been described above, the present invention is not limited to these.
For example, in the above-described embodiment, the thin film transistor having a top gate structure has been described as a representative, but the present invention can also be applied to a bottom gate thin film transistor.

Moreover, the manufacturing method of the thin-film transistor of this invention can also add the process of 1 or 2 or more arbitrary purposes to the process as mentioned above as needed.
In addition, the structure of each part of the thin film transistor, the electronic device, and the electronic apparatus of the present invention can be replaced with an arbitrary one that can exhibit the same function, or an arbitrary configuration can be added.

Next, specific examples of the present invention will be described.
1. Production of Thin Film Transistor In the following, pure water was used as water unless otherwise specified.
(Example 1)
[1] Source and drain electrode forming step [1-I] Resist layer forming step First, a glass substrate having an average thickness of 1 mm was prepared and washed with water (cleaning liquid).
Next, hexamethyldisilazane vapor was sprayed onto the surface of the glass substrate on the side where the resist layer is to be formed, and hexamethyldisilazane was adsorbed on this surface. Then, it wash | cleaned using water (washing | cleaning liquid).

Next, after applying a photoresist (trade name TSMR series, manufactured by Tokyo Ohka Co., Ltd.) on a glass substrate by spin coating, a coating was formed by performing a pre-bake treatment at a heating temperature of 120 ° C. and a heating time of 10 minutes. .
Next, the coating film was developed after being irradiated (exposed) with ultraviolet rays through a photomask. Thus, a resist layer having an opening in a region where the source electrode and the drain electrode are formed was formed. The obtained resist layer had a thickness Y of 30 nm.

[1-II] Hydrophilic treatment step Next, oxygen plasma treatment was performed in the opening of the resist layer.
Various conditions for the oxygen plasma treatment are as follows.
・ Oxygen-containing gas: Mixed gas of oxygen gas and tetrafluoromethane gas ・ Mixed gas mixture ratio: Oxygen gas: Tetrafluoromethane gas = 80: 20 (vol%)
・ Gas flow rate: 400sccm
RF power: 0.05 W / cm ²
・ Oxygen plasma irradiation time: 60 seconds

[1-III] Water Repellent Treatment Step Next, a fluorine plasma treatment was performed on the surface of the resist layer opposite to the substrate.
Various conditions for the fluorine plasma treatment are as follows.
・ Fluorine-containing gas: Tetrafluoromethane gas ・ Gas flow rate: 350 sccm
RF power: 0.05 W / cm ²
Fluorine plasma irradiation time: 30 seconds or more The water repellency on the upper surface of the resist layer was made higher than the water repellency in the opening by the hydrophilic treatment process and the water repellency treatment process.

[1-IV] Liquid Material Supplying Step Next, a liquid material (viscosity (room temperature) 5 cps) in which polyethylenedioxythiophene is dispersed in water is applied to this opening by an inkjet method (droplet discharge method) (one droplet) The thickness X of the obtained source electrode and drain electrode was supplied to be 45 nm.
At this time, the relationship AB between the contact angle A [°] of the liquid material to the resist layer and the contact angle B [°] of the liquid material to the opening was 50 [°].
[1-V] Electrode Formation Step Thereafter, the glass substrate supplied with the liquid material was dried at 80 ° C. for 10 minutes to obtain a source electrode and a drain electrode.

[1-VI] Resist Layer Removal Step Next, after removing the resist layer by oxygen plasma treatment, the glass substrate on which the source electrode and the drain electrode were formed was washed sequentially with water and methanol.
Various conditions for the oxygen plasma treatment are as follows.
・ Oxygen-containing gas: Oxygen gas ・ Gas flow rate: 100 sccm
RF power: 0.05 W / cm ²
・ Oxygen plasma irradiation time: 120 seconds

[2] Organic Semiconductor Layer Step Next, a 1% wt / vol toluene solution of F8T2 (fluorene-bithiophene copolymer) is applied on a glass substrate by a spin coating method (2400 rpm), and then at 60 ° C. for 10 minutes. And dried. Thereby, an organic semiconductor layer having an average thickness of 50 nm was formed.
[3] Gate Insulating Layer Formation Step Next, a 5% wt / vol butyl acetate solution of polymethyl methacrylate (PMMA) is applied on the organic semiconductor layer by a spin coating method (2400 rpm), and then 60 ° C. × 10 Dry in minutes. Further, a 2% wt / vol isopropyl alcohol solution of polyvinylphenol was applied by spin coating (2400 rpm) and then dried at 60 ° C. for 10 minutes. Thereby, a gate insulating layer having an average thickness of 500 nm was formed.

[4] Gate Electrode Formation Step Next, an aqueous dispersion of polyethylene dioxythiophene (viscosity (room temperature) 5 cps) is applied to the portion corresponding to the region between the source electrode and the drain electrode on the gate insulating layer by inkjet. After applying by the method (droplet discharge method) (the amount of one droplet is 20 pL), it was dried at 80 ° C. for 10 minutes. Thereby, a gate electrode having an average thickness of 100 nm was formed.
Through the above steps, the thin film transistor shown in FIG. 1 was manufactured.

(Examples 2 to 5)
The thin film transistor shown in FIG. 1 was manufactured in the same manner as in Example 1 except that the thickness of the resist layer to be formed was changed as shown in Table 1 in the resist layer forming step [1-I].
(Examples 6 and 7)
The thin film transistor shown in FIG. 1 was manufactured in the same manner as in Example 1 except that the conductive material contained in the liquid material was changed as shown in Table 1 in the liquid material supply step [1-IV].
(Example 8)
The thin film transistor shown in FIG. 1 was manufactured in the same manner as in Example 7 except that in the resist layer removing step [1-VI], the resist layer was removed by argon plasma treatment instead of oxygen plasma treatment.

(Comparative Example 1)
The thin film transistor shown in FIG. 1 was manufactured in the same manner as in Example 1 except that in the resist layer forming step [1-I], the thickness of the resist layer was 200 nm.
(Comparative Example 2)
A thin film transistor shown in FIG. 1 was manufactured in the same manner as in Comparative Example 1 except that the resist layer removing step [1-VI] was omitted.
(Comparative Example 3)
The thin film transistor shown in FIG. 1 was manufactured in the same manner as in Comparative Example 1, except that the thickness of the obtained source electrode and drain electrode was changed to 45 nm in the resist layer forming step [1-I].

2. Evaluation The values of the OFF current and the ON current were measured for the thin film transistors manufactured in each Example and each Comparative Example.
Here, the OFF current is a value of a current flowing between the source electrode and the drain electrode when no gate voltage is applied.

The ON current was measured by setting the gate voltage to −40V and the potential difference between the source electrode and the drain electrode to 30V.
Therefore, the smaller the absolute value of the OFF current and the larger the absolute value of the ON current, the more thin film transistors having better characteristics.
These values are shown in Table 2.

As shown in Table 2, all the thin film transistors manufactured in each example had a small absolute value of the OFF current and a large absolute value of the ON current, and were excellent in characteristics. This is a result suggesting that the resist layer is surely removed (peeled) without causing deterioration or deterioration of the source electrode and the drain electrode.
In addition, the characteristics of the thin film transistor manufactured with the thickness X of the source electrode and the drain electrode / the thickness Y of the resist layer 2 to 10 and the thin film transistor manufactured with the thickness Y of the resist layer 5 to 50 nm are as follows. It showed a tendency to improve.

Furthermore, the characteristics of the thin film transistors (Examples 3 and 4) satisfying both tend to be particularly improved.
On the other hand, Comparative Example 1 and Comparative Example 3 had a small absolute value of the ON current. This result is presumed to be due to the deterioration of the characteristics of the thin film transistor because the source and drain electrodes were altered and deteriorated when the resist layer was peeled off.

In Comparative Example 2, the OFF current was large, and a sufficient ON / OFF ratio was not obtained. This result is presumed to be because impurities in the resist layer, fluorine ions doped in the resist layer, etc. contributed to the generation of the OFF current in order not to remove the resist layer.
As can be seen from a comparison between Example 7 and Example 8, when the source electrode and the drain electrode are made of Cu, the characteristics of the thin film transistor are improved by removing the resist layer by oxygen plasma treatment. This suggests that the oxygen plasma treatment oxidizes Cu present on the surface of these electrodes, thereby increasing the work function of the source electrode and improving the efficiency of hole injection into the organic semiconductor layer. This is the result.

It is a figure which shows embodiment of a thin-film transistor, (a) is a longitudinal cross-sectional view, (b) is a top view. It is a figure (longitudinal sectional drawing) for demonstrating the manufacturing method of the thin-film transistor shown in FIG. It is a figure (longitudinal sectional drawing) for demonstrating the manufacturing method of the thin-film transistor shown in FIG. It is a figure (longitudinal sectional drawing) for demonstrating the manufacturing method of the thin-film transistor shown in FIG. 1 is a longitudinal sectional view showing an embodiment when an electronic device of the present invention is applied to an electrophoretic display device. FIG. 6 is a block diagram illustrating a configuration of an active matrix device included in the electrophoretic display device illustrated in FIG. 5. It is a perspective view which shows embodiment at the time of applying the electronic device of this invention to electronic paper. It is a figure which shows embodiment at the time of applying the electronic device of this invention to a display.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Thin film transistor 2 ... Substrate 3 ... Source electrode 4 ... Drain electrode 5 ... Organic semiconductor layer 51 ... Channel region 6 ... Gate insulating layer 7 ... Gate electrode 8 ... Resist layer 8 '... Coating 82 ... Opening 9 Liquid material 20 Electrophoretic display device 30 Active matrix device 31 Data line 32 Scan line 40 Electrophoretic display 41 Pixel electrode 42 Microcapsule 420 Electrophoresis dispersion liquid 421, 422 Electrophoretic particles 43 Transparent electrode 44 Transparent substrate 45 Binder material 50 Substrate 600 Electronic paper 601 Main body 602 Display unit 800 Display 801 Main body 802a, 802b Transport roller pair 803 Hole 804 Transparent glass plate 805 ... Insertion slot 806 ... Terminal part 807 ... Socket 808 ... Controller 809 ... Operation part

Claims (18)

A thin film transistor for manufacturing a thin film transistor provided on a substrate and having a source electrode, a drain electrode, a gate electrode, an organic semiconductor layer, and a gate insulating layer that insulates the gate electrode from the source electrode and the drain electrode A manufacturing method comprising:
A first step of forming a resist layer having an opening having a shape corresponding to the source electrode and the drain electrode and having a thickness smaller than the thickness of the source electrode and the drain electrode to be formed;
A second step of supplying a liquid material containing a conductive material and / or a precursor thereof and an aqueous solvent into the opening of the resist layer so as to be thicker than the thickness of the resist layer;
A third step of removing the aqueous solvent from the liquid material to obtain the source electrode and the drain electrode;
A method of manufacturing a thin film transistor, comprising a fourth step of removing the resist layer.   2. The relationship of X / Y of 2 to 10 is satisfied, where the thickness of the source and drain electrodes to be formed is X [nm] and the thickness of the resist layer is Y [nm]. The manufacturing method of the thin-film transistor of description.   3. The method of manufacturing a thin film transistor according to claim 1, further comprising a water repellent treatment step of performing a water repellent treatment on a surface of the resist layer opposite to the substrate prior to the second step.   The method for manufacturing a thin film transistor according to claim 3, wherein the water repellent treatment is a fluorine plasma treatment.   5. The method for manufacturing a thin film transistor according to claim 1, further comprising a hydrophilic treatment step of performing a hydrophilic treatment in the opening prior to the second step.   The method of manufacturing a thin film transistor according to claim 5, wherein the hydrophilic treatment is an oxygen plasma treatment.   The method of manufacturing a thin film transistor according to claim 1, wherein in the second step, the liquid material is supplied by a droplet discharge method.   In the second step, when the contact angle of the liquid material with respect to the resist layer is A [°] and the contact angle of the liquid material with respect to the opening is B [°], a relationship of AB ≧ 15 is satisfied. The method for producing a thin film transistor according to claim 1, wherein:   The method for manufacturing a thin film transistor according to any one of claims 1 to 8, wherein, in the third step, the temperature at which the aqueous solvent is removed is 20 to 200 ° C.   The method for manufacturing a thin film transistor according to claim 1, wherein in the fourth step, the resist layer is removed by plasma treatment.   The method of manufacturing a thin film transistor according to claim 10, wherein the plasma treatment is an oxygen plasma treatment.   The method of manufacturing a thin film transistor according to claim 1, wherein the conductive material is mainly composed of a conductive polymer material and / or a metal material.   The method for manufacturing a thin film transistor according to claim 1, wherein the conductive polymer material is mainly composed of PEDOT (polyethylenedioxythiophene).   14. The method of manufacturing a thin film transistor according to claim 1, wherein the metal material is mainly composed of at least one of Cu, Ni, Ag, or an alloy containing these.   A thin film transistor manufactured by the method for manufacturing a thin film transistor according to claim 1.   A thin film transistor circuit comprising the thin film transistor according to claim 15.   An electronic device comprising the thin film transistor circuit according to claim 16. An electronic apparatus comprising the electronic device according to claim 17.

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