WO2015033881A1

WO2015033881A1 - Organic thin film transistor

Info

Publication number: WO2015033881A1
Application number: PCT/JP2014/072889
Authority: WO
Inventors: 昌弘三谷
Original assignee: シャープ株式会社
Priority date: 2013-09-04
Filing date: 2014-09-01
Publication date: 2015-03-12

Abstract

This organic thin film transistor (1) is provided with: a gate electrode (12); an organic semiconductor layer (19a) that is arranged so as to face the gate electrode (12); a gate insulating film that is interposed between the gate electrode (12) and the organic semiconductor layer (19a); a source electrode (14a) and a drain electrode (14b), which are connected to the organic semiconductor layer (19a) for the purpose of supplying an electric current to the organic semiconductor layer (19a); and a body electrode (17a) which is connected to the organic semiconductor layer (19a) for the purpose of extracting charges stored in the organic semiconductor layer (19a).

Description

Organic thin film transistor

The present invention relates to an organic thin film transistor, and more particularly to an organic thin film transistor including an organic semiconductor layer as a semiconductor layer.

Conventionally, for thin display devices such as thin displays, thin tablet displays, and electronic paper, active matrix backplanes in which switching elements are arranged in a grid are widely used for display display.

In the thin film transistor substrate, for example, a thin film transistor is provided as a switching element for each pixel which is the minimum unit of an image. For the semiconductor layer (active layer) of the thin film transistor used for the switching element, an inorganic semiconductor material is mainly used, such as an oxide semiconductor such as amorphous silicon, polysilicon, or indium gallium zinc oxide.

However, in the case of manufacturing a thin film transistor using an inorganic semiconductor material, a vacuum system is used, and further, high-temperature process treatment is required, which increases the manufacturing cost and requires a heat-resistant substrate. And other restrictions occur. In addition, since an inorganic semiconductor material is used, for example, when the substrate is bent, cracks are likely to occur, which is unsuitable for flexible display devices.

Therefore, in recent years, an organic thin film transistor having an organic semiconductor layer formed of an organic semiconductor material has been proposed. Since the organic thin film transistor can be formed at a low temperature (less than 200 ° C.), the selectivity of the substrate is improved. In addition, since the organic semiconductor layer can be formed using a coating process, the manufacturing cost can be reduced. Furthermore, due to the flexibility of organic materials (such as organic semiconductors and organic insulating films) constituting the device, it is also suitable for flexible display devices.

For example, JP-A-2004-55654 (Patent Document 1) and JP-A-2010-161312 (Patent Document 2) disclose such organic thin film transistors.

An organic thin film transistor disclosed in Patent Document 1 includes a source electrode and a drain electrode arranged so as to be opposed to each other, and an organic semiconductor layer having carrier mobility formed between the source electrode and the drain electrode. Is provided. The source electrode and the drain electrode are made of materials having different work functions.

By adopting such a configuration, it is possible to realize an organic semiconductor transistor excellent in electrical characteristics with a small charge injection barrier to the organic semiconductor.

An organic thin film transistor disclosed in Patent Document 2 includes a source electrode and a drain electrode that are arranged so as to be opposed to each other, and an organic semiconductor layer having carrier mobility formed between the source electrode and the drain electrode. Is provided. A thiol compound layer made of a benzenethiol compound having an electron donating group bonded to a benzene ring is formed on a portion of the source electrode and the drain electrode that are in electrical contact with the organic semiconductor layer.

With this configuration, the degree of carrier injection from the source electrode into the organic semiconductor layer can be changed, and as a result, only the threshold voltage can be selectively controlled.

JP 2004-55654 A JP 2010-161312 A

Generally, in the case of an inorganic thin film transistor using an inorganic semiconductor material, when the TFT (Thin Film Transistor) characteristics are measured in a state where the inorganic thin film transistor is irradiated with light (Photo state), the dark state (Dark It is well known that the threshold voltage shift and off-current increase occur instantaneously and the TFT characteristics fluctuate temporarily compared to the case where the TFT characteristics are measured in the state). On the other hand, when the TFT characteristics are measured again in the dark state after the light irradiation is stopped, the shift of the TFT characteristics is instantaneously restored to show the characteristics in the original dark state. That is, it is known that an inorganic thin film transistor responds reversibly and instantaneously to ON / OFF of light.

On the other hand, in the case of an organic thin film transistor using an organic semiconductor material, when the TFT characteristics are measured in a state where the organic thin film transistor is irradiated with light (Photo state), as in the case of the inorganic thin film transistor, the threshold voltage is reduced. Shifts and off current increases instantly. However, when the TFT characteristics are measured again in the dark state after the light irradiation is stopped, the threshold voltage shift does not immediately return to the original state, but slowly takes a few hours to a day to return to the original dark state. Return to characteristics.

Also, when the TFT characteristics are measured in the dark state after the light is turned on / off without applying a voltage in the photo state, the TFT characteristics hardly change. That is, in the organic thin film transistor, the characteristic shift occurs only when a voltage is applied while applying light, and the TFT characteristic changes very slowly with respect to the subsequent light blocking.

This phenomenon is very problematic when the organic thin film transistor is used as a backplane of a liquid crystal display device. This is because, in a liquid crystal display device, strong light hits an organic thin film transistor in a state where a voltage is applied by light from a backlight. Similarly, in an organic EL (Electro Luminescence) display device, light hits an organic thin film transistor in a state where a voltage is applied by self-luminescence.

When the TFT characteristics are greatly shifted due to the light from the backlight or the self-emission light hitting the organic thin film transistor, and the fluctuation of the characteristics does not return for a long time, the pixels of the liquid crystal display device or the organic EL display device are not driven correctly, and the desired The problem arises that the video cannot be obtained. For this reason, it is important to extract charges (electrons or holes) accumulated in the organic semiconductor layer by the light.

Here, in the organic thin film transistor disclosed in Patent Document 1, since a material having a work function different from that of the drain electrode is used as a material of the source electrode, when the work function of the source electrode is separated from the ionization potential to some extent, it is externally applied. The effect of extracting the charge (for example, electrons in the case of a p-type semiconductor) accumulated in the organic semiconductor layer by the light can be obtained, but conversely, the injection barrier between the source electrode and the organic semiconductor layer is increased and accumulated in the organic semiconductor layer. It may be difficult to inject charges (for example, holes) having the opposite polarity to the generated charges (for example, electrons). In this case, it becomes difficult for the current to flow, and there is a concern that display quality may be deteriorated due to insufficient writing of a voltage necessary for pixel lighting.

In the organic thin film transistor substrate disclosed in Patent Document 2, it is not sufficiently considered to remove charges accumulated in the organic semiconductor layer by light applied to the organic semiconductor layer from the outside. In addition, when a material having a work function different from that of the drain electrode is used as the material of the source electrode, there is a concern that it is difficult for current to flow as described above.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an organic thin film transistor that can easily extract charges accumulated in an organic semiconductor layer and has stable TFT characteristics. There is to do.

An organic thin film transistor according to the present invention includes a gate electrode, an organic semiconductor layer disposed to face the gate electrode, a gate insulating layer positioned between the gate electrode and the organic semiconductor layer, and the organic semiconductor layer. Connected to the organic semiconductor layer, and a body electrode connected to the organic semiconductor layer and for removing charges accumulated in the organic semiconductor layer.

In the organic thin film transistor according to the present invention, the work function of the body electrode is preferably different from the work functions of the source electrode and the drain electrode.

In the organic thin film transistor according to the present invention, the body electrode is preferably made of a material different from that of the source electrode and the drain electrode.

In the organic thin film transistor according to the present invention, a monomolecular film is preferably formed at the interface between the body electrode and the organic semiconductor layer.

In the organic thin film transistor according to the present invention, the organic semiconductor layer is preferably a p-type organic semiconductor layer. In this case, the work function of the body electrode is the same as that of the source electrode or the drain electrode. It is preferably smaller than the work function.

In the organic thin film transistor according to the present invention, the organic semiconductor layer is preferably an n-type organic semiconductor layer, and the work function of the body electrode is larger than the work function of the source electrode or the drain electrode. It is preferable.

According to the present invention, it is possible to easily extract charges accumulated in the organic semiconductor layer and to provide an organic thin film transistor having stable TFT characteristics.

1 is a plan view of an organic thin film transistor according to Embodiment 1. FIG. 2 is a cross-sectional view corresponding to line II (A) -II (A) and a cross-sectional view corresponding to line II (B) -II (B) shown in FIG. 1 in a thin film transistor substrate including the organic thin film transistor shown in FIG. It is a figure which shows an example of an energy level in case the organic thin-film transistor shown in FIG. 1 has a p-type organic-semiconductor layer. It is a figure which shows an example of an energy level in case the organic thin-film transistor shown in FIG. 1 has an n-type organic-semiconductor layer. It is a figure which shows the process of forming the basecoat layer of the thin-film transistor substrate shown in FIG. It is a figure which shows the process of forming the gate electrode of the thin-film transistor substrate shown in FIG. It is a figure which shows the process of forming the gate insulating layer of the thin-film transistor substrate shown in FIG. It is a figure which shows the process of forming the source electrode and drain electrode of a thin-film transistor substrate shown in FIG. It is a figure which shows the 1st process of the process of forming the body electrode of the thin-film transistor substrate shown in FIG. It is a figure which shows the 2nd process of the process of forming the body electrode of the thin-film transistor substrate shown in FIG. It is a figure which shows the 1st process of the process of forming the organic-semiconductor layer, protective layer, and mask layer of a thin-film transistor substrate shown in FIG. It is a figure which shows the 2nd process of the process of forming the organic-semiconductor layer, protective layer, and mask layer of a thin-film transistor substrate shown in FIG. It is a figure which shows the 1st process of the process of forming the interlayer protective layer and interlayer mask layer of a thin-film transistor substrate shown in FIG. It is a figure which shows the 2nd process of the process of forming the interlayer protective layer and interlayer mask layer of a thin-film transistor substrate shown in FIG. FIG. 3 is a diagram showing a process of forming a pixel electrode, a source electrode terminal, and a body electrode terminal of the thin film transistor substrate shown in FIG. It is sectional drawing at the time of dividing | segmenting along the extending direction of a body electrode, and the sectional view at the time of dividing the thin-film transistor substrate which comprises the organic thin-film transistor which concerns on Embodiment 2 along the direction where a source electrode and a drain electrode are arranged. It is a figure which shows the process of forming the source electrode of the thin film transistor substrate shown in FIG. 16, a drain electrode, and a body electrode. It is a figure which shows the process of surface-treating to the body electrode shown in FIG. It is sectional drawing at the time of dividing | segmenting along the extending direction of a body electrode, and the sectional view at the time of dividing the thin-film transistor substrate which comprises the organic thin-film transistor which concerns on Embodiment 3 along the direction where a source electrode and a drain electrode are arranged. It is a figure which shows the 1st process of the process of forming the organic-semiconductor layer of the thin-film transistor substrate shown in FIG. It is a figure which shows the 2nd process of the process of forming the organic-semiconductor layer of the thin-film transistor substrate shown in FIG. It is a figure which shows the 1st process of the process of forming the source electrode and drain electrode of a thin-film transistor substrate shown in FIG. It is a figure which shows the 2nd process of the process of forming the source electrode and drain electrode of a thin-film transistor substrate shown in FIG. It is a figure which shows the 1st process of the process of forming the body electrode of the thin-film transistor substrate shown in FIG. It is a figure which shows the 2nd process of the process of forming the body electrode of the thin-film transistor substrate shown in FIG. It is a figure which shows the 1st process of the process of forming the interlayer protective layer and interlayer mask layer of a thin-film transistor substrate shown in FIG. It is a figure which shows the 2nd process of the process of forming the interlayer protective layer and interlayer mask layer of a thin-film transistor substrate shown in FIG. FIG. 20 is a diagram illustrating a process of forming a pixel electrode, a source electrode terminal, and a body electrode terminal of the thin film transistor substrate illustrated in FIG. 19. FIG. 6 is a cross-sectional view when a thin film transistor substrate including an organic thin film transistor according to a fourth embodiment is divided along a direction in which source and drain electrodes are arranged, and a cross-sectional view when divided along an extending direction of a body electrode. It is a figure which shows the process of forming the source electrode of the thin-film transistor substrate shown in FIG. 29, a drain electrode, and a body electrode. It is a figure which shows the process of surface-treating to the body electrode shown in FIG. It is sectional drawing at the time of dividing along the extending direction of a body electrode, and sectional drawing at the time of dividing the thin-film transistor substrate which comprises the organic thin-film transistor which concerns on Embodiment 5 along the direction where a source electrode and a drain electrode are arranged. It is a figure which shows the process of forming the source electrode and drain electrode of a thin-film transistor substrate shown in FIG. FIG. 33 is a diagram showing a first step of forming a body electrode of the thin film transistor substrate shown in FIG. 32. It is a figure which shows the 2nd process of the process of forming the body electrode of the thin-film transistor substrate shown in FIG. It is a figure which shows the 1st process of the process of forming the organic-semiconductor layer of the thin-film transistor substrate shown in FIG. 32, a 1st protective layer, and a mask layer. It is a figure which shows the 2nd process of the process of forming the organic-semiconductor layer of the thin-film transistor substrate shown in FIG. 32, a 1st protective layer, and a mask layer. FIG. 33 is a diagram showing a step of forming a second protective layer and a gate insulating layer of the thin film transistor substrate shown in FIG. 32. FIG. 33 is a diagram showing a step of forming a gate electrode of the thin film transistor substrate shown in FIG. 32. FIG. 33 is a diagram showing a first step of forming an interlayer protective layer and an interlayer mask layer of the thin film transistor substrate shown in FIG. 32. FIG. 33 is a diagram showing a second step of forming an interlayer protective layer and an interlayer mask layer of the thin film transistor substrate shown in FIG. 32. FIG. 33 is a diagram showing a process of forming a pixel electrode, a source electrode terminal, and a body electrode terminal of the thin film transistor substrate shown in FIG. 32. It is sectional drawing at the time of dividing along the extending direction of a body electrode, and sectional drawing at the time of dividing the thin-film transistor substrate which comprises the organic thin-film transistor which concerns on Embodiment 6 along the direction where a source electrode and a drain electrode are arranged. FIG. 44 is a diagram showing a process of forming a source electrode, a drain electrode, and a body electrode of the thin film transistor substrate shown in FIG. 43. FIG. 44 is a diagram showing a step of performing a surface treatment on the body electrode shown in FIG. 43. It is sectional drawing at the time of dividing along the extending direction of a body electrode, and sectional drawing at the time of dividing the thin-film transistor substrate which comprises the organic thin-film transistor concerning Embodiment 7 along the direction where a source electrode and a drain electrode are arranged. FIG. 47 is a diagram showing a first step of forming an organic semiconductor layer of the thin film transistor substrate shown in FIG. 46. It is a figure which shows the 2nd process of the process of forming the organic-semiconductor layer of the thin-film transistor substrate shown in FIG. FIG. 47 is a diagram showing a first step of forming a source electrode and a drain electrode of the thin film transistor substrate shown in FIG. 46. FIG. 47 is a diagram showing a second step of forming the source electrode and the drain electrode of the thin film transistor substrate shown in FIG. 46. FIG. 47 is a diagram showing a first step of forming a body electrode of the thin film transistor substrate shown in FIG. 46. FIG. 47 is a diagram showing a second step of forming the body electrode of the thin film transistor substrate shown in FIG. 46. FIG. 47 is a diagram showing a step of forming a gate insulating layer of the thin film transistor substrate shown in FIG. 46. FIG. 47 is a diagram showing a step of forming a gate electrode of the thin film transistor substrate shown in FIG. 46. FIG. 47 is a diagram showing a first step of forming an interlayer protective layer and an interlayer mask layer of the thin film transistor substrate shown in FIG. 46. FIG. 47 is a diagram showing a second step of forming the interlayer protective layer and the interlayer mask layer of the thin film transistor substrate shown in FIG. 46. FIG. 47 is a diagram showing a process of forming a pixel electrode, a source electrode terminal, and a body electrode terminal of the thin film transistor substrate shown in FIG. 46. FIG. 9 is a cross-sectional view when a thin film transistor substrate including an organic thin film transistor shown in Embodiment 8 is divided along a direction in which a source electrode and a drain electrode are arranged, and a cross-sectional view when divided along an extending direction of a body electrode. FIG. 59 is a diagram showing a process of forming a source electrode, a drain electrode, and a body electrode of the thin film transistor substrate shown in FIG. 58. FIG. 60 is a diagram showing a step of performing a surface treatment on the body electrode shown in FIG. 59. It is a figure which shows the top view of the organic thin-film transistor which concerns on Embodiment 9. FIG. It is a figure which shows the energy level of the organic thin-film transistor shown in FIG. It is a schematic sectional drawing which shows the liquid crystal display device which comprises the thin-film transistor substrate shown in FIG. FIG. 64 is a diagram showing a first example of an equivalent circuit diagram of the liquid crystal display device shown in FIG. 63. FIG. 64 is a diagram showing a second example of an equivalent circuit diagram of the liquid crystal display device shown in FIG. 63. It is a schematic sectional drawing which shows the 1st form of the organic electroluminescence display which comprises the thin-film transistor substrate shown in FIG. FIG. 67 is a diagram showing a first example of an equivalent circuit diagram of the organic EL display device shown in FIG. 66. FIG. 67 is a diagram showing a second example of an equivalent circuit diagram of the organic EL display device shown in FIG. 66. FIG. 67 is a diagram showing a third example of an equivalent circuit diagram of the organic EL display device shown in FIG. 66. It is a schematic sectional drawing which shows the 2nd form of the organic electroluminescence display which comprises the thin-film transistor substrate shown in FIG. FIG. 71 is a diagram showing a first example of an equivalent circuit diagram of the organic EL display device shown in FIG. 70.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, the same or common parts are denoted by the same reference numerals in the drawings, and description thereof will not be repeated.

(Embodiment 1)
FIG. 1 is a plan view of the organic thin film transistor according to the first embodiment. 2A and 2B are cross-sectional views corresponding to the line II (A) -II (A) shown in FIG. 1 and II (B) -II (II) in the thin film transistor substrate having the organic thin film transistor shown in FIG. B) It is sectional drawing corresponding to a line. With reference to FIG. 1, FIG. 2 (A), and (B), the organic thin-film transistor which concerns on this Embodiment, and the thin-film transistor substrate provided with the same are demonstrated.

As shown in FIG. 1 and FIGS. 2A and 2B, an organic thin film transistor 1 according to the present embodiment includes a substrate 10, a base coat layer 11 formed so as to cover the main surface of the substrate 10, and a base coat. A gate electrode 12 formed on the layer 11, a gate insulating layer 13 formed on the base coat layer 11 so as to cover the gate electrode 12, a source electrode 14a, a drain electrode 14b formed on the gate insulating layer 13, and A body electrode 17a and an organic semiconductor layer 19a connected to the source electrode 14a, the drain electrode 14b, and the body electrode 17a are provided.

The source electrode 14 a and the drain electrode 14 b are arranged side by side along a direction that is spaced apart from each other and intersects the direction in which the gate electrode 12 extends, and at least a part of the source electrode 14 a and the drain electrode 14 b sandwich the gate insulating layer 13. Are provided to overlap. The source electrode 14a and the drain electrode 14b are parts for allowing a current to flow through the organic semiconductor layer 19a.

The body electrode 17a is disposed separately from the source electrode 14a and the drain electrode 14b, and is provided so as not to overlap the gate electrode 12. The body electrode 17a is a part for removing charges accumulated in the organic semiconductor layer 19a.

The organic semiconductor layer 19a covers the body electrode 17a and a portion of the gate insulating layer 13 located between the source electrode 14a and the drain electrode 14b, and on the upper surface of each of the source electrode 14a, the drain electrode 14b, and the body electrode 17a. At least partly touches. A portion of the organic semiconductor layer 19a located between the source electrode 14a and the drain electrode 14b faces the gate electrode 12 so as to sandwich the gate insulating layer 13 therebetween.

The organic thin film transistor 1 further includes a protective layer 20a provided on the organic semiconductor layer 19a and a mask layer 21A provided on the protective layer 20a.

As shown in FIGS. 2A and 2B, the thin film transistor substrate 2 is provided so as to cover the organic thin film transistor 1, the interlayer protective layer 22 provided so as to cover the organic thin film transistor 1, and the interlayer protective layer 22. The interlayer mask layer 23A, the source electrode terminal 25a connected to the source electrode 14a of the organic thin film transistor 1, the pixel electrode 25b connected to the drain electrode 14b of the organic thin film transistor 1, and the body electrode 17a of the organic thin film transistor 1 are connected. Body electrode terminal 25c.

Contact

holes

24a, 24b, and 24c are formed in the interlayer mask layer 23A and the interlayer protection layer 22. The contact hole 24a is provided so as to reach the source electrode 14a from the surface side of the interlayer mask layer 23A. The contact hole 24b is provided so as to reach the drain electrode 14b from the surface side of the interlayer mask layer 23A. The contact hole 24c is provided so as to reach the body electrode 17a from the surface side of the interlayer mask layer 23A.

The source electrode terminal 25a is connected to the source electrode 14a via the contact hole 24a, the pixel electrode 25b is connected to the drain electrode 14b via the contact hole 24b, and the body electrode terminal 25c is connected to the contact hole 24c. Is connected to the body electrode 17a.

As the organic semiconductor layer 19a, a p-type organic semiconductor layer or an n-type organic semiconductor layer can be employed. Depending on the material of the organic semiconductor layer 19a, the material of the source electrode, the drain electrode, and the body electrode can be appropriately selected. Details thereof will be described later.

FIG. 3 is a diagram illustrating an example of energy levels when the organic thin film transistor illustrated in FIG. 1 includes a p-type organic semiconductor layer. As shown in FIG. 3, when the organic semiconductor layer 19a is p-type, HOMO of the organic semiconductor material (Highest Occupied Molecular Orbital: highest occupied molecular orbital) level close to the work function W _S, a metal having a W _D The source electrode S (source electrode 14a) and the drain electrode D (drain electrode 14b) are formed using the material. Further, LUMO of the organic semiconductor material: forming a body electrode BD (body electrode 17a) using (Lowest Unoccupied Molecular Orbital lowest unoccupied molecular orbital) metallic material having a work function close W _BD level. That is, the body electrode BD is formed by a different metal material as a source electrode S and the drain electrode D, the work function W _BD of body electrode BD is the work function W _S of the source electrode S and the drain electrode _D, smaller than W _D Become.

With this configuration, in the organic thin-film transistor 1 of the present embodiment, since the work function W _S of the source electrode S is close to HOMO level of the organic semiconductor layer 19a, the hole of the p-type organic semiconductor It can be easily injected into the layer 19a. For this reason, a large current can flow in the organic thin film transistor 1. Further, since the work function W _BD of the body electrode BD is lower than the LUMO level of the organic semiconductor layer 19a, electrons accumulated in the organic semiconductor layer 19a can be easily extracted through the body electrode BD. As a result, in the organic thin film transistor 1 according to the present embodiment, stable TFT characteristics can be realized by suppressing a shift in TFT characteristics during light irradiation or light OFF.

FIG. 4 is a diagram illustrating an example of energy levels when the organic thin film transistor illustrated in FIG. 1 includes an n-type organic semiconductor layer. As shown in FIG. 4, when the organic semiconductor layer 19a is n-type, LUMO of the organic semiconductor material (Lowest Unoccupied Molecular Orbital: lowest unoccupied molecular orbital) close to the level work function W _S, a metal material having a W _D The source electrode S (source electrode 14a) and the drain electrode D (drain electrode 14b) are formed by using them. The organic HOMO of the semiconductor material: forming a body electrode BD (body electrode 17a) using a metal material having a (Highest Occupied Molecular Orbital highest occupied molecular orbital) near the level the work function W _BD. That is, the body electrode BD is formed by a different metal material as a source electrode S and the drain electrode D, the work function W _BD of body electrode BD is the work function W _S of the source electrode S and the drain electrode _D, greater than W _D Become.

With this configuration, in the organic thin-film transistor 1 according to this embodiment, by the work function W _S of the source electrode S is smaller than the LUMO level of the organic semiconductor layer 19a, an electron of an n-type organic It can be easily injected into the semiconductor layer 19a. For this reason, a large current can flow in the organic thin film transistor 1. Moreover, since the work function W _BD of the body electrode BD is close to the HOMO level of the organic semiconductor layer 19a, holes accumulated in the organic semiconductor layer 19a can be easily extracted through the body electrode BD. As a result, in the organic thin film transistor 1 according to the present embodiment, stable TFT characteristics can be realized by suppressing a shift in TFT characteristics during light irradiation or light OFF.

FIGS. 5A and 5B to FIGS. 15A and 15B are diagrams showing respective steps for manufacturing the thin film transistor substrate shown in FIGS. 2A and 2B. With reference to FIGS. 5A and 5B to FIGS. 15A and 15B, a method of manufacturing the thin film transistor substrate 2 shown in FIGS. 2A and 2B will be described.

FIGS. 5A and 5B are diagrams showing a base coat layer forming step of the thin film transistor substrate 2 shown in FIGS. 2A and 2B. As shown in FIGS. 5A and 5B, a base coat layer 11 made of an inorganic insulating film, an organic insulating film, or a combination of both is formed on the substrate 10 for the purpose of barrier properties such as moisture and oxygen. To do.

As the substrate 10, a glass substrate, a plastic substrate such as PEN, PES, or PET, or a substrate in which a film material such as PEN, PES, PET, PI, or aramid or an organic insulating film is formed on a glass substrate as a support substrate Etc. can be adopted.

When using an inorganic insulating film, the base coat layer 11 can be formed by forming a nitride film, an oxide film, a nitrided oxide film or the like by, for example, a CVD method. Moreover, when using an organic insulating film, it can form by apply | coating resin, such as a polyimide and zeonore, for example by a spin coat method, a slit coat method, etc.

6 (A) and 6 (B) are diagrams showing a process of forming the gate electrode of the thin film transistor substrate shown in FIGS. 2 (A) and 2 (B). As shown in FIGS. 6A and 6B, the gate electrode 12 is formed to a thickness of about 100 to 400 nm by vacuum deposition, sputtering, or the like. The gate electrode 12 can be formed by forming a metal film of Al, Al—Si, Cu, W, Mo, MoW, Ti, Cr, or the like and a metal film having a laminated structure in which these are laminated. . In order to improve the adhesion between the base coat layer and the gate electrode, it is desirable to form an adhesion layer such as Ti or Cr at the interface.

When the gate electrode 12 is formed using a vacuum evaporation method, a separate patterning step is not required by depositing the metal film using a metal mask.

In the case of forming the gate electrode 12 using the sputtering method, first, the metal film (gate electrode film) is formed on the entire main surface of the base coat layer 11, and then a photosensitive resist is applied on the gate electrode film. . Thereafter, the photosensitive resist is patterned by photolithography (exposure / development). Subsequently, the gate electrode 12 is patterned by wet etching or dry etching of the gate electrode film using the photosensitive resist as a mask.

Wet etching is performed using SLA etchant (composition: H ₃ PO ₄ (phosphoric acid): H ₂ O: HNO ₃ (nitric acid): CH ₃ COOH (acetic acid) = 16: 2: 1: 1), nitric acid, phosphoric acid, acetic acid , Using hydrofluoric acid and an etchant combining these. Dry etching is performed using a gas of SF ₆ , CHF ₃ , CF ₄ , Cl ₂ , O ₂ , Ar, or a combination thereof. After the etching, the photosensitive resist used as a mask is removed with a stripping solution. Thereby, the gate electrode 12 is formed.

Further, the pattern forming method of the gate electrode 12 is not limited to the above method, and a printing method using an electrically conductive paste, an electrolytic plating method, an electroless plating method, or the like can be employed.

FIGS. 7A and 7B are views showing a process of forming a gate insulating layer of the thin film transistor substrate shown in FIGS. 2A and 2B. As shown in FIG. 7, after applying an organic insulating material such as polyvinylphenol (PVP) or polystyrene (PS) so as to cover the gate electrode 12 by spin coating, slit coating, ink jetting, printing, or the like. By baking, the gate insulating layer 13 is formed with a thickness of about 200 nm to 1000 nm.

8A and 8B are diagrams showing a process of forming a source electrode and a drain electrode of the thin film transistor substrate shown in FIGS. 2A and 2B. As shown in FIGS. 8A and 8B, the source electrode 14a and the drain electrode 14b are formed on the gate insulating layer 13 to a thickness of about 100 to 400 nm by vacuum deposition, sputtering, or the like.

The materials of the source electrode 14a and the drain electrode 14b are the same material, and can be selected according to the type of the organic semiconductor layer 19a formed in a later process.

When the organic semiconductor layer 19a is p-type, a material having a large work function and a small hole injection barrier to the p-type organic semiconductor layer 19a is adopted as a material for the source electrode 14a and the drain electrode 14b. A metal film of Pt, Rh, Au, Cu, Ag, Ta, W, Mo, MoW, MnO ₂ , MnO ₃ , Ni, Ti, Cr, or the like, and a metal film having a laminated structure in which these are laminated are combined. Can be adopted.

For example, when pentacene (HOMO level: about 5.3 eV) is adopted as the material of the p-type organic semiconductor layer 19a, Au (work function: about 5.0 eV) is used as the material of the source electrode 14a and the drain electrode 14b. Can be adopted. In this case, since the hole injection barrier height is small (about 0.3 eV), holes can be easily injected from the source electrode 14a into the organic semiconductor layer 19a, and a large current flows through the organic thin film transistor 1. be able to.

When the organic semiconductor layer 19a is n-type, a material having a small work function and a small barrier for injecting electrons into the n-type organic semiconductor layer 19a may be employed as the material for the source electrode 14a and the drain electrode 14b. Preferably, a metal film of Na, Mg, Ca, Al, Ag, Cu, Au, W, Mo, MoW, Ni, Ti, Cr or the like and a metal film having a laminated structure in which these are laminated and combined can be employed. .

For example, when C60 fullerene (LUMO level: about 4.5 eV) is adopted as the material of the n-type organic semiconductor layer 19a, the material of the source electrode 14a and the drain electrode 14b is Al (work function: about 4.3 eV). ) Can be adopted. In this case, since the electron injection barrier height is small (about −0.2 eV), electrons can be easily injected from the source electrode 14a to the organic semiconductor layer 19a, and a large current flows through the organic thin film transistor 1. Can do.

Further, in order to improve the adhesion between the gate insulating layer 13 and the source electrode 14a and drain electrode 14b, an adhesion layer such as Ti or Cr may be formed between the gate insulating layer 13 and the source electrode 14a and drain electrode 14b. Good.

In addition, when forming the source electrode 14a and the drain electrode 14b using a vacuum evaporation method, the process of patterning separately by evaporating the said metal film using a metal mask becomes unnecessary.

When the source electrode 14a and the drain electrode 14b are formed by sputtering, first, the metal film (source / drain electrode film) is formed over the entire main surface of the gate insulating layer 13. Then, a photosensitive resist is applied on the source / drain electrode film. Thereafter, the photosensitive resist is patterned by photolithography (exposure / development). Subsequently, the source electrode 14a and the drain electrode 14b are patterned by performing wet etching or dry etching on the gate electrode film using the photosensitive resist as a mask.

Wet etching is aqua regia, SLA etchant (composition; H ₃ PO ₄ (phosphoric acid): H ₂ O: HNO ₃ (nitric acid): CH ₃ COOH (acetic acid) = 16: 2: 1: 1), nitric acid, phosphorus An acid, acetic acid, hydrofluoric acid, and an etchant that combines these are used. Dry etching is performed using a gas of SF ₆ , CHF ₃ , CF ₄ , Cl ₂ , O ₂ , Ar, or a combination thereof. After the etching, the photosensitive resist used as a mask is removed with a stripping solution. Thereby, the source electrode 14a and the drain electrode 14b are formed.

Further, the pattern forming method of the source electrode 14a and the drain electrode 14b is not limited to the above method, and a printing method, an electroplating method, an electroless plating method, or the like using a conductive paste can be employed.

9A, 9B, 10A, and 10B show the first and second steps of the process of forming the body electrode of the thin film transistor substrate shown in FIGS. 2A and 2B. FIG. When the body electrode 17a is formed by using the sputtering method and the lift-off method, first, as shown in FIGS. 9A and 9B, the gate insulating layer 13 is formed so as to cover the source electrode 14a and the drain electrode 14b. After the positive photosensitive resist 15 is applied to the entire surface on the main surface, only the region where the body electrode 17a is to be formed is exposed and developed to remove the photosensitive resist 15. At this time, the cross-sectional shape of the photosensitive resist 15 is desirably a reverse taper type so that the photosensitive resist 15 can be easily lifted off after the body electrode film 17 is formed. Other regions except the region where the body electrode 17a is to be formed are protected by the photosensitive resist 15.

Next, the body electrode film 17 is formed to a thickness of about 100 to 400 nm on the entire surface of the substrate on which the photosensitive resist 15 has been formed by sputtering. Subsequently, as shown in FIGS. 10A and 10B, the body resist 17 is formed on the gate insulating layer 13 by removing the photosensitive resist 15 used as the deposition mask by lifting off with a stripping solution.

Further, in order to improve the adhesion between the gate insulating layer 13 and the body electrode 17a, an adhesion layer such as Ti or Cr may be formed between the gate insulating layer 13 and the body electrode 17a.

The material of the body electrode 17a can be selected according to the type of the organic semiconductor layer 19a and the material of the source electrode 14a and the drain electrode 14b.

In the case where the organic semiconductor layer 19a is p-type, in order to extract the electrons accumulated in the p-type organic semiconductor layer 19a by light irradiation, the material of the body electrode 17a is selected from the source electrode 14a and the drain electrode 14b. It is desirable to use a material having a small work function, and a laminated structure in which metal films such as Na, Mg, Ca, Al, Ag, Cu, Au, W, Mo, MoW, Ni, Ti, and Cr are laminated and combined. The metal film can be used.

For example, as described above, pentacene (HOMO level: about 5.3 eV) is adopted as the material of the p-type organic semiconductor layer 19a, and Au (work function: about 5.0 eV) is used as the material of the source electrode 14a and the drain electrode 14b. ), Ca (work function: about 2.9 eV) can be used as the material of the body electrode 17a.

In this case, since the work function (about 2.9 eV) of the body electrode 17a made of Ca is lower than the LUMO level (about 3.5 eV) of the organic semiconductor layer, the organic semiconductor layer is interposed via the body electrode 17a. The electrons accumulated in 19a can be easily extracted. As a result, in the organic thin film transistor 1 according to the present embodiment, stable TFT characteristics can be realized by suppressing a shift in TFT characteristics during light irradiation or light OFF.

In the case where the organic semiconductor layer 19a is n-type, the material of the body electrode 17a is selected from the source electrode 14a and the drain electrode 14b in order to extract holes accumulated in the n-type organic semiconductor layer 19a by light irradiation. It is desirable to use a material having a large work function, such as Pt, Rh, Au, Cu, Ag, Ta, Al, W, Mo, MoW, MnO ₂ , MnO ₃ , Ni, Ti, Cr, etc. A metal film having a laminated structure in which the layers are stacked and combined can be employed.

For example, as described above, C60 fullerene (HOMO level: about 6.2 eV, LUMO level: about 4.5 eV) is adopted as the material of the n-type organic semiconductor layer 19a, and Al is used as the material of the source electrode 14a and the drain electrode 14b. When (work function: about 4.3 eV) is employed, Pt (work function: about 5.7 eV) can be employed as the material of the body electrode 17a.

In this case, since the work function (about 5.7 eV) of the body electrode 17a made of Pt is close to the HOMO level (about 6.2 eV) of the organic semiconductor layer 19a, the organic semiconductor layer is interposed via the body electrode 17a. The holes accumulated in 19a can be easily extracted. As a result, in the organic thin film transistor 1 according to the present embodiment, stable TFT characteristics can be realized by suppressing a shift in TFT characteristics during light irradiation or light OFF.

In addition, when forming the body electrode 17a using a vacuum evaporation method, the process of patterning separately by evaporating the said metal film using a metal mask becomes unnecessary. Moreover, the pattern formation method of the body electrode 17a is not limited to the above method, and a printing method, an electroplating method, an electroless plating method, or the like using a conductive paste can be employed.

FIGS. 11A and 11B and FIGS. 12A and 12B show the first step of forming the organic semiconductor layer, protective layer, and mask layer of the thin film transistor substrate shown in FIGS. It is a figure which shows a 2nd process. When forming the organic semiconductor layer 19a, the protective layer 20a, and the mask layer 21A as shown in FIGS. 11A and 11B and FIGS. 12A and 12B, first, spin coating, slit coating is performed. The organic semiconductor film 19 is formed on the entire substrate on which the source electrode 14a, the drain electrode 14b, and the body electrode 17a are formed using a method, an inkjet method, a printing method, a vapor deposition method, or the like. The organic semiconductor film 19 is formed with a thickness of about 40 to 200 nm.

Subsequently, a protective film 20 made of an inorganic insulating film, an organic insulating film, or a laminated film combining these is formed on the organic semiconductor film 19 using the above method. Next, the organic insulating film 21 for forming the mask layer 21A is formed on the protective film 20 using the above method. The protective film 20 and the organic insulating film 21 are each formed with a thickness of about 40 to 1000 nm.

As a material for the p-type organic semiconductor film 19 (organic semiconductor layer 19a), pentacene, soluble pentacene, TIPS pentacene, P3HT (Poly [3-hexyltiophene-2,5-diyl]), copper phthalocyanine, or the like may be employed. it can. Examples of the material of the n-type organic semiconductor film 19 (organic semiconductor layer 19a) include perylene diimide derivatives, C60 fullerene, fullerene derivatives, PCBM ([6,6] -Phenyl-C61-Butyric Acid Methyl Ester), SIMEF (Silylmethyl [ 60] fullerene) etc. can be adopted.

As the material of the protective film 20 for forming the protective layer 20a, a nitride film, an oxide film, a nitrided oxide film, or the like can be employed when an inorganic insulating film is used, and when an organic insulating film is used. Parylene, CYTOP (registered trademark) manufactured by Asahi Glass Co., Ltd., or the like can be used. Moreover, as a material of the protective film 20, what combined the above-mentioned inorganic insulating film and organic insulating film is employable.

As the organic insulating film 21, for example, a negative organic insulating film can be adopted. The organic insulating film 21 has photosensitivity, and a part thereof functions as a mask. The organic insulating film 21 is exposed and developed using a light shielding mask 82. At this time, the portion of the organic insulating film 21 that has been exposed to light that has passed through the opening 82a provided in the light shielding mask 82 is cured to become the mask layer 21A and remains on the protective film 20 after development. On the other hand, the portion 21B of the organic insulating film 21 that has not been exposed to light is melted by development.

Subsequently, dry etching is performed using the mask layer 21A as a mask. At this time, the organic semiconductor film 19 and the protective film 20 are collectively etched and patterned, whereby the organic semiconductor layer 19a, the protective layer 20a, and the mask are formed in an island shape as shown in FIGS. Layer 21A is formed. As shown in FIG. 1, the stacked body of the organic semiconductor layer 19a, the protective layer 20a, and the mask layer 21A is separated from the source electrode 14a and the drain electrode 14b that are arranged to face each other. It is formed so as to cover a part of the formed body electrode 17a.

Dry etching is performed using SF6, CHF3, CF4, O2, Ar, or a combination of these gases. The protective layer 20a and the mask layer 21A are left as they are without ashing or the like in order to avoid damage to the organic semiconductor layer 19a due to ashing or the like.

The organic thin film transistor 1 according to the present embodiment can be manufactured through the above steps.

FIGS. 13A and 13B and FIGS. 14A and 14B show the first step of forming the interlayer protective layer and the interlayer mask layer of the thin film transistor substrate shown in FIGS. 2A and 2B. It is a figure which shows a 2nd process. As shown in FIGS. 13A and 13B and FIGS. 14A and 14B, when forming the interlayer protective layer 22 and the interlayer mask layer 23A, first, spin coating, slit coating, Interlayer protection composed of an inorganic insulating film, an organic insulating film, or a laminated film combining these over the entire substrate on which the organic semiconductor layer 19a, the protective layer 20a, and the mask layer 21A are formed using an inkjet method, a printing method, a vapor deposition method, or the like. Layer 22 is formed. Subsequently, the organic insulating film 23 for forming the interlayer mask layer 23A is formed on the interlayer protective layer 22 by using the above method. The interlayer protective layer 22 and the organic insulating film 23 are each formed with a thickness of about 200 to 1000 nm.

As a material for forming the interlayer protective layer 22, when using an inorganic insulating film, a nitride film, an oxide film, a nitrided oxide film, or the like can be adopted. When using an organic insulating film, parylene, Asahi Glass Co., Ltd. CYTOP (registered trademark) or the like can be used, and a combination of these inorganic insulating films and organic insulating films can also be used.

As the organic insulating film 23, for example, a negative organic insulating film can be adopted. The organic insulating film 23 has photosensitivity, and a part thereof functions as a mask. The organic insulating film 23 is exposed and developed using a light shielding mask 81. At this time, the portion of the organic insulating film 23 that has been exposed to light that has passed through the opening 81a provided in the light shielding mask 81 is cured to become the interlayer mask layer 23A, and remains on the interlayer protective layer 22 after development. On the other hand, the portion 23B of the organic insulating film 23 that was not exposed to light is melted by development.

Therefore, the light shielding mask 81 shields the region of the organic insulating film 23 where the

contact holes

24a, 24b, 24c are formed and the region where the contact hole (not shown) reaching the gate electrode 12 is formed.

Subsequently, dry etching is performed using the interlayer mask layer 23A as a mask to form

contact holes

24a, 24b, and 24c as shown in FIGS. At this time, a part of the interlayer protective layer 22 and the gate insulating layer 13 located on the gate electrode 12 that is not covered with the organic semiconductor layer 19a is also etched in the same manner, so that a contact hole (not shown) reaching the gate electrode 12 is formed. ) May be formed.

FIGS. 15A and 15B are diagrams showing a process of forming a pixel electrode, a source electrode terminal, and a body electrode terminal of the thin film transistor substrate shown in FIGS. 2A and 2B. As shown in FIGS. 15A and 15B, a source electrode terminal 25a, a pixel electrode 25b, and a body electrode terminal 25c are formed by vacuum deposition, sputtering, or the like. The source electrode terminal 25a, the pixel electrode 25b, and the body electrode terminal 25c may be formed of the same material or different materials. As a material for forming these, a conductive film such as Au, Ag, Cu, Al, or Mo, or a transparent conductive film such as IZO, ITO, CNT, or graphene can be used. In a liquid crystal display device or a bottom emission type OLED display device, it is desirable to use a transparent conductive film such as IZO, ITO, ZnO, or SnO for the pixel electrode 25b in order to extract light from the opening. On the other hand, in a top emission type OLED display device, a reflective electrode such as Al, Al alloy, Ag, or Ag alloy is used for the pixel electrode 25b in order to extract light from the upper portion, or IZO, ITO, or the like is used as an upper layer. It is desirable to use a laminated structure electrode in which a transparent conductive film and a reflective electrode made of Al, Al alloy, Ag, Ag alloy, Mo, Cr or the like are combined in the lower layer. In this embodiment, as an example, a case where the source electrode terminal 25a, the pixel electrode 25b, and the body electrode terminal 25c are formed of the same material and a transparent conductive film is used as the material will be described.

When the sputtering method is used, the transparent conductive film is formed on the entire substrate on which the interlayer mask layer 23A is formed, and the transparent conductive film is patterned into a predetermined pattern, whereby the source electrode terminal 25a and the pixel electrode are formed. 25b and body electrode terminal 25c are formed. In the case of forming the source electrode terminal 25a, the pixel electrode 25b, and the body electrode terminal 25c by using a vacuum evaporation method, a separate patterning process is not required by depositing the metal film using a metal mask.

Further, when the source electrode terminal 25a, the pixel electrode 25b, and the body electrode terminal 25c are formed by using a spin coating method, a slit coating method, an ink jet method, a printing method, or the like, as materials for forming these, Au, An ink containing nanoparticles such as Ag, Cu, Al, ITO, CNT, and graphene can be employed.

The source electrode terminal 25a, the pixel electrode 25b, and the body electrode terminal 25c are each formed with a thickness of about 100 to 600 nm. A gate electrode terminal (not shown) may be formed simultaneously with the source electrode terminal 25a, the pixel electrode 25b, and the body electrode terminal 25c so as to cover the surface of the contact hole reaching the gate electrode 12 with the same material. .

Through the above-described steps, the thin film transistor substrate 2 including the organic thin film transistor 1 having a bottom gate-bottom contact structure can be manufactured.

In the organic thin film transistor 1 and the thin film transistor substrate 2 having the same according to the present embodiment, the body electrode 17a is formed of a material different from that of the source electrode 14a and the drain electrode 14b, so that the source electrode 14a and the drain electrode 14b are formed. The work function and the work function of the body electrode 17a are different.

By adopting such a configuration, in the organic thin film transistor 1 and the thin film transistor substrate 2 having the organic thin film transistor 1, charges (electrons or holes) accumulated in the organic semiconductor layer 19a through the body electrode 17a as described above. Can be easily removed. Thereby, stable TFT characteristics can be realized while suppressing a shift in TFT characteristics during light irradiation or light OFF.

In addition, by manufacturing a liquid crystal display panel or an organic EL panel using the thin film transistor substrate 2, a liquid crystal panel or an organic EL panel having a stable display quality that is hardly affected by light such as backlight, external light, and self-light emission. Can be obtained.

Moreover, since the organic thin film transistor 1 according to the present embodiment has a bottom contact structure in which the source electrode 14a and the drain electrode 14b are formed before the organic semiconductor layer 19a is formed, the source electrode 14a and the drain electrode 14b are formed. In addition, photolithography can be used instead of the lift-off method. For this reason, the organic thin-film transistor 1 with a short channel length can be manufactured, and a high-definition display and a fine device can be manufactured using this.

(Embodiment 2)
16A and 16B are a cross-sectional view and a body electrode extending direction when the thin film transistor substrate including the organic thin film transistor according to the second embodiment is divided along the direction in which the source electrode and the drain electrode are arranged. It is sectional drawing at the time of dividing along. With reference to FIGS. 16A and 16B, an organic thin film transistor 1A according to the present embodiment and a thin film transistor substrate 2A including the same will be described. 16A shows a portion corresponding to FIG. 2A, and FIG. 16B shows a portion corresponding to FIG. 2B.

As shown in FIGS. 16A and 16B, the organic thin film transistor 1A according to the present embodiment and the thin film transistor substrate 2A having the same are the organic thin film transistor 1 according to the first embodiment and the thin film transistor substrate 2 having the same. When the body electrode 17b is subjected to a surface treatment, the body electrode 17b has a work function different from that of the source electrode 14a and the drain electrode 14b. It is the same.

Specifically, the source electrode 14a, the drain electrode 14b, and the body electrode 17b are made of the same metal material, and an SAM (Self Align Monolayer) film (self) is formed on the interface between the body electrode 17b and the organic semiconductor layer 19a. An organized monolayer 93) is formed. Even when the source electrode 14a, the drain electrode 14b, and the body electrode 17b are made of the same metal material, the source electrode 14a and the self-assembled monolayer 93 are formed so as to cover the surface of the body electrode 17b. The work function of the drain electrode 14b and the work function of the body electrode 17b can be made different. The self-assembled monolayer 93 can be selected according to the type of the organic semiconductor layer 19a.

When the organic semiconductor layer 19a is p-type, MBT (4-Methyl Benzene Thiol) can be used as the material of the self-assembled monolayer 93.

In this case, a metal material having a work function close to the HOMO (Highest Occupied Molecular Orbital) level of the organic semiconductor material is adopted as the material of the source electrode 14a, the drain electrode 14b, and the body electrode 17b.

By forming the self-assembled monolayer 93 composed of the above MBT (4-Methyl Benzene Thiol) so as to cover the surface of the body electrode 17b, the work function of the body electrode 17b is the same as that of the source electrode 14a and It becomes smaller than the work function of the drain electrode 14b.

Further, when the organic semiconductor layer 19a is n-type, HBT (4-Hydroxy Benzene Thiol) or FBT (Fluoro Benzene Thiol) can be adopted as the material of the self-assembled monolayer 93.

In this case, a metal material having a work function close to the LUMO (Lowest Unoccupied Molecular Orbital) level of the organic semiconductor material is adopted as the material of the source electrode 14a, the drain electrode 14b, and the body electrode 17b.

By forming the self-assembled monolayer 93 composed of the above-mentioned HBT (4-Hydroxy Benzene Thiol) or FBT (Fluoro Benzene Thiol) so as to cover the surface of the body electrode 17b, the work function of the body electrode 17b Becomes larger than the work functions of the source electrode 14a and the drain electrode 14b.

Note that, regardless of whether an n-type organic semiconductor layer or a p-type organic semiconductor layer is used, instead of forming the self-assembled monolayer 93, the surface of the body electrode 17b is subjected to plasma treatment and UV treatment. Thus, the work function of the body electrode 17b can be made different from that of the source electrode 14a and the drain electrode 14b.

The method for manufacturing the thin film transistor substrate according to the present embodiment basically conforms to the method for manufacturing the thin film transistor substrate 2 according to the first embodiment, and has a surface treatment step, so that the thin film transistor substrate 2 according to the first embodiment. This is different from the manufacturing method.

In the method of manufacturing the organic thin film transistor 1A according to the present embodiment, first, in the step of forming the base coat layer, the step of forming the gate electrode, and the step of forming the gate insulating layer, the thin film transistor substrate according to the first embodiment The base coat layer 11, the gate electrode 12, and the gate insulating layer 13 are formed on the substrate 10 by performing the same process as in the manufacturing method 2.

FIGS. 17A and 17B are diagrams showing a process of forming a source electrode, a drain electrode, and a body electrode of the thin film transistor substrate shown in FIGS. 16A and 16B. As shown in FIGS. 17A and 17B, a source electrode 14a, a drain electrode 14b, and a body electrode 17b patterned in a predetermined shape by a vacuum deposition method, a sputtering method, or the like are gated to a thickness of about 100 to 400 nm. It is formed on the insulating layer 13.

The materials of the source electrode 14a, the drain electrode 14b, and the body electrode 17b are the same material, and can be selected according to the type of the organic semiconductor layer 19a.

When the organic semiconductor layer 19a is p-type, the source electrode 14a, the drain electrode 14b, and the body electrode 17b are made of a material having a high work function and a small hole injection barrier to the p-type organic semiconductor layer 19a. Pt, Rh, Au, Cu, Ag, Ta, W, Mo, MoW, MnO ₂ , MnO ₃ , Ni, Ti, Cr, etc., and a laminated structure in which these are laminated and combined The metal film can be used.

For example, when pentacene (HOMO level: about 5.3 eV) is adopted as the material of the p-type organic semiconductor layer 19a, the material of the source electrode 14a, the drain electrode 14b, and the body electrode 17b is Au (work function: about 5.0 eV) can be employed. In this case, since the hole injection barrier height is small (about 0.3 eV), holes can be easily injected into the organic semiconductor layer 19a from the source electrode 14a and the drain electrode 14b, and the organic thin film transistor 1A can be injected. A large current can flow.

When the organic semiconductor layer 19a is n-type, the material for the source electrode 14a, the drain electrode 14b, and the body electrode 17b is a material having a small work function and a small barrier for electron injection into the n-type organic semiconductor layer 19a. It is preferable to adopt metal films such as Na, Mg, Ca, Al, Ag, Cu, Au, W, Mo, MoW, Ni, Ti, and Cr, and a metal film having a laminated structure in which these are stacked and combined. can do.

For example, when C60 fullerene (LUMO level: about 4.5 eV) is adopted as the material of the n-type organic semiconductor layer 19a, the material of the source electrode 14a, the drain electrode 14b, and the body electrode 17b is Au (work function: About 4.5 eV) can be employed. In this case, since the electron injection barrier height is small (about 0.5 eV), electrons can be easily injected into the organic semiconductor layer 19a from the source electrode 14a and the drain electrode 14b, and a large current flows into the organic thin film transistor 1A. Can flow.

Further, in order to improve the adhesion between the gate insulating layer 13 and the source electrode 14a, drain electrode 14b, and body electrode 17b, Ti, Cr are interposed between the gate insulating layer 13 and the source electrode 14a, drain electrode 14b, and body electrode 17b. An adhesive layer such as

In addition, when forming the source electrode 14a, the drain electrode 14b, and the body electrode 17b using a vacuum evaporation method, the process of patterning separately by evaporating the said metal film using a metal mask becomes unnecessary.

When the source electrode 14a, the drain electrode 14b, and the body electrode 17b are formed by sputtering, first, the above metal film (source / drain / body electrode film) is formed over the entire main surface of the gate insulating layer 13. ), A photosensitive resist is applied on the source / drain / body electrode film. Thereafter, the photosensitive resist is patterned by photolithography (exposure / development). Subsequently, the source electrode 14a, the drain electrode 14b, and the body electrode 17b are patterned by wet etching or dry etching of the gate electrode film using the photosensitive resist as a mask.

Wet etching is aqua regia, SLA etchant (composition; H ₃ PO ₄ (phosphoric acid): H ₂ O: HNO ₃ (nitric acid): CH ₃ COOH (acetic acid) = 16: 2: 1: 1), nitric acid, phosphorus An acid, acetic acid, hydrofluoric acid, and an etchant combining these are used. The dry etching is performed using SF ₆ , CHF ₃ , CF ₄ , Ar gas, and a combination thereof. After the etching, the photosensitive resist used as a mask is removed with a stripping solution. Thereby, the source electrode 14a and the drain electrode 14b are formed.

The pattern forming method of the source electrode 14a, the drain electrode 14b, and the body electrode 17b is not limited to the above method, and a printing method, an electroplating method, an electroless plating method, or the like using a conductive paste may be employed. it can.

18 (A) and 18 (B) are diagrams showing a step of performing a surface treatment on the body electrode shown in FIGS. 17 (A) and 17 (B). As shown in FIGS. 18A and 18B, in the step of performing the surface treatment on the body electrode 17b, first, the entire surface of the substrate 10 on which the source electrode 14a, the drain electrode 14b, and the body electrode 17b are formed is exposed to light. After the application of the resist 16, the resist is patterned by photolithography (exposure / development) so that only the surface of the body electrode 17b is exposed. Subsequently, a self-assembled monolayer 93 is applied to the entire surface of the substrate 10 on which the patterned photosensitive resist 16 is formed, and only the work function of the body electrode 17b is changed. Finally, the resist is stripped with a stripping solution to remove the photosensitive resist 16 and the self-assembled monolayer 93 applied on the photosensitive resist 16. Thereby, the self-assembled monomolecular film 93 is formed so as to cover the surface of the body electrode 17b, and the work function of the body electrode 17b can be changed.

Although not shown, only the work function of the body electrode 17b may be changed by dropping the self-assembled monolayer 93 only in the body electrode 17b region by an ink jet method instead of the photolithography method. In this case, resist coating or patterning by photolithography is not required, and the self-assembled monomolecular film can be directly formed so as to cover the surface of the body electrode 17b, so that the number of masks can be reduced. Thereby, manufacturing cost can be reduced.

As described above, when the organic semiconductor layer is p-type, the work function of the body electrode 17b is desirably smaller than the work functions of the source electrode 14a and the drain electrode 14b in order to extract accumulated electrons. For example, MBT (4-Methyl Benzene Thiol) can be employed as the self-assembled monolayer 93 that reduces the work function.

For example, when pentacene is adopted as the p-type organic semiconductor material and Au is adopted as the material of the source electrode 14a, the drain electrode 14b and the body electrode 17b, MBT is applied on the surface of the body electrode 17b to The work function of the electrode (Au) can be reduced from about 5.0 eV to about 4.3 eV.

Alternatively, as another example, when pentacene is used as the p-type organic semiconductor material and Cu is used as the material of the source electrode 14a, the drain electrode 14b, and the body electrode 17b, MBT is applied on the surface of the body electrode 17b. By doing so, the work function of the body electrode (Cu) can be reduced from 4.7 eV to about 4.0 eV.

As a result, the work function of the body electrode 17b can be reduced to a value close to the LUMO level (about 3.5 eV) of pentacene, which is the p-type organic semiconductor layer 19a, so that the organic semiconductor layer 19a is interposed via the body electrode 17b. The electrons accumulated inside can be easily extracted. Thereby, stable TFT characteristics can be realized while suppressing a shift in TFT characteristics during light irradiation or light OFF.

As described above, when the organic semiconductor layer is n-type, the work function of the body electrode 17b is preferably larger than the work functions of the source electrode 14a and the drain electrode 14b in order to extract accumulated holes. For example, HBT (4-Hydroxy Benzene Thiol) or FBT (Fluoro Benzene Thiol) can be employed as the self-assembled monolayer that increases the work function.

For example, when C60 fullerene is adopted as the n-type organic semiconductor material and Au is adopted as the material of the source electrode 14a, the drain electrode 14b and the body electrode 17b, HBT or FBT is applied to the surface of the body electrode 17b. The work function of the body electrode (Au) can be increased from about 5.0 eV to about 5.2 eV.

Alternatively, as another example, when C60 fullerene is used as the n-type organic semiconductor material and Al is used as the material of the source electrode 14a, the drain electrode 14b, and the body electrode 17b, HBT or FBT is used as the surface of the body electrode 17b. The work function of the body electrode (Al) can be increased from 4.3 eV to 4.5 eV.

As a result, the work function of the body electrode 17b can be brought close to the HOMO level (about 6.2 eV) of C60 fullerene, which is the n-type organic semiconductor layer 19a, so that it is accumulated in the organic semiconductor layer 19a via the body electrode 17b. Holes can be easily extracted. Thereby, stable TFT characteristics can be realized while suppressing a shift in TFT characteristics during light irradiation or light OFF.

Subsequently, in the step of forming the organic semiconductor layer, the first protective layer, and the mask layer, the same process as that of the method for manufacturing the thin film transistor substrate according to the first embodiment is performed, thereby providing the organic thin film transistor 1A according to the present embodiment. Can be manufactured.

Next, in the step of forming the interlayer protective layer and the interlayer mask layer, and the step of forming the pixel electrode, the source electrode terminal, and the body electrode terminal, the same process as the method for manufacturing the thin film transistor substrate 2 according to the first embodiment is performed. By applying, the thin film transistor substrate 2A including the organic thin film transistor 1A having the bottom gate-bottom contact structure can be manufactured.

In the organic thin film transistor 1A according to the present embodiment and the thin film transistor substrate 2A including the same, after the source electrode 14a, the drain electrode 14b, and the body electrode 17b are formed of the same material, the surface is formed only on the surface of the body electrode 17b. By performing the treatment, the work functions of the source electrode 14a and the drain electrode 14b are different from the work function of the body electrode 17a.

Thereby, also in the organic thin film transistor 1A according to the present embodiment and the thin film transistor substrate 2A including the organic thin film transistor 1A, substantially the same effects as the organic thin film transistor 1 according to the first embodiment and the thin film transistor substrate 2 including the same are obtained.

Further, in the method of manufacturing the thin film transistor substrate 2A according to the present embodiment, the body electrode 17b can be formed from the same material as the source electrode 14a and the drain electrode 14b, thereby reducing the number of processes and material costs. Manufacturing cost can be reduced.

(Embodiment 3)
19A and 19B are a cross-sectional view and a body electrode extending direction when the thin film transistor substrate including the organic thin film transistor according to the third embodiment is divided along the direction in which the source electrode and the drain electrode are arranged. It is sectional drawing at the time of dividing along. With reference to FIGS. 19A and 19B, an organic thin film transistor 1B according to the present embodiment and a thin film transistor including the same will be described. FIG. 19A shows a portion corresponding to FIG. 2A, and FIG. 19B shows a portion corresponding to FIG.

As shown in FIGS. 19A and 19B, the organic thin film transistor 1B according to the present embodiment and the thin film transistor substrate 2B having the same are the organic thin film transistor 1 according to the first embodiment and the thin film transistor substrate 2 having the same. Is different in that the source electrode 14a and the drain electrode 14b have a top contact structure instead of a bottom contact structure, and a protective layer and a mask layer are not formed accordingly. It is almost the same.

Specifically, the organic thin film transistor 1B according to the present embodiment includes a substrate 10, a base coat layer 11 formed so as to cover the main surface of the substrate 10, a gate electrode 12 formed on the base coat layer 11, A gate insulating layer 13 formed on the base coat layer 11 so as to cover the gate electrode 12; an organic semiconductor layer 19a disposed on the gate insulating layer 13 so as to face the gate electrode 12 so as to sandwich the gate insulating layer 13; A source electrode 14a, a drain electrode 14b, and a body electrode 17a formed on the gate insulating layer 13 so as to be connected to the upper surface of the organic semiconductor layer 19a.

Further, by forming the body electrode 17a with a material different from that of the source electrode 14a and the drain electrode 14b, the work function of the source electrode 14a and the drain electrode 14b is different from the work function of the body electrode 17a.

The manufacturing method of the thin film transistor substrate 2B according to the present embodiment is basically the same as the manufacturing method of the thin film transistor substrate 2 according to the first embodiment, and the organic semiconductor is formed before the step of forming the source electrode 14a and the drain electrode 14b. The difference is that the step of forming the layer 19a is provided and the step of forming a protective layer and a mask layer on the organic semiconductor layer 19a is not provided.

In the method of manufacturing the organic thin film transistor 1B according to the present embodiment, first, in the step of forming the base coat layer, the step of forming the gate electrode, and the step of forming the gate insulating layer, the thin film transistor substrate according to the first embodiment The base coat layer 11, the gate electrode 12, and the gate insulating layer 13 are formed on the substrate 10 by performing the same process as in the manufacturing method 2.

FIGS. 20A and 20B and FIGS. 21A and 21B are a first step and a second step of the step of forming the organic semiconductor layer of the thin film transistor substrate shown in FIGS. FIG. As shown in FIGS. 20A and 20B, in the first step of forming the organic semiconductor layer, a source electrode is formed using a spin coating method, a slit coating method, an ink jet method, a printing method, a vapor deposition method, or the like. The organic semiconductor film 19 is formed to a thickness of 40 to 200 nm on the entire substrate on which the drain electrode 14b, the body electrode 17a, and the drain electrode 14b are formed.

As a material of the p-type organic semiconductor film 19 (organic semiconductor layer 19a), for example, pentacene, soluble pentacene, TIPS pentacene, P3HT (Poly [3-hexyltiophene-2,5-diyl]), copper phthalocyanine, or the like is employed. Can do. In the present embodiment, for example, it is preferable to employ copper phthalocyanine having excellent chemical resistance.

Examples of the material of the n-type organic semiconductor film 19 (organic semiconductor layer 19a) include perylene diimide derivatives, C60 fullerene, fullerene derivatives, PCBM ([6,6] -Phenyl-C61-Butyric Acid Methyl Ester), SIMEF (Silylmethyl [ 60] fullerene) etc. can be adopted. In the present embodiment, for example, it is preferable to employ C60 fullerene having excellent chemical resistance.

Subsequently, after the photosensitive resist 26 is applied to the entire substrate 10 on which the organic semiconductor film 19 is formed, the photosensitive resist 26 is patterned by photolithography (exposure / development), and the region where the organic semiconductor film 19 is to be islanded is formed. The photosensitive resist 26 is formed only on the top.

Next, as shown in FIGS. 21A and 21B, in the second step of forming the organic semiconductor layer, dry etching is performed using the photosensitive resist 26 as a mask. At this time, the organic semiconductor layer 19 is formed in an island shape on the gate insulating layer 13 by performing patterning by etching the organic semiconductor film 19.

Dry etching is performed using a gas such as SF ₆ , CHF ₃ , CF ₄ , Cl ₂ , O ₂ , Ar, or a combination thereof. Subsequently, the entire substrate 10 is immersed in a stripping solution, and the upper surface of the organic semiconductor layer 19a is exposed by removing the photosensitive resist 26 on the organic semiconductor layer 19a.

22A, 22B, 23A, and 23B show a first step and a first step of forming the source electrode and the drain electrode of the thin film transistor substrate shown in FIGS. 19A and 19B. It is a figure which shows 2 processes.

As shown in FIGS. 22A and 22B, in the first step of forming the source electrode 14a and the drain electrode 14b, a positive type photosensitive film is formed on the entire substrate 10 on which the organic semiconductor layer 19a is formed. A conductive resist 27 is applied. Subsequently, only the portions where the source electrode 14a and the drain electrode 14b are to be formed are exposed, and then developed to remove the photosensitive resist 27. At this time, the cross-sectional shape of the photosensitive resist 27 is desirably a reverse taper type so that the photosensitive resist 27 can be easily lifted off after the source / drain electrode film 14 is formed. Other regions except the region where the source electrode 14a and the drain electrode 14b are formed are protected with a photosensitive resist 27.

Next, the source / drain electrode film 14 is formed to a thickness of about 100 to 400 nm on the entire substrate 10 patterned with the photosensitive resist 27 by sputtering. At this time, a part of the source / drain electrode film 14 is cut by the step of the photosensitive resist pattern, so that the source / drain electrode film 14 is in contact with the end of the upper surface of the organic semiconductor layer 19a.

Subsequently, as shown in FIGS. 23A and 23B, in the second step of forming the source electrode and the drain electrode, the photosensitive resist 27 used as a deposition mask is removed by lifting off with a stripping solution. Thereby, the source electrode 14a and the drain electrode 14b are formed.

In addition, although the case where the source electrode 14a and the drain electrode 14b are formed by using a sputtering method and a lift-off method has been described as an example, the present invention is not limited to this, and is not limited thereto. The source electrode 14a and the drain electrode 14b may be formed using a method or the like.

When the organic semiconductor layer 19a is p-type, a material having a large work function and a small hole injection barrier to the p-type organic semiconductor layer 19a is adopted as a material for the source electrode 14a and the drain electrode 14b. Pt, Rh, Au, Cu, Ag, Ta, W, Mo, MoW, MnO2, MnO3, Ni, Ti, Cr, etc., and a metal film having a laminated structure in which these are laminated are employed. be able to.

For example, when copper phthalocyanine (HOMO level: about 5.0 eV) is adopted as the material of the p-type organic semiconductor layer 19a, Au (work function: about 5.0 eV) is used as the material of the source electrode 14a and the drain electrode 14b. ) Can be adopted. In this case, since there is almost no hole injection barrier, holes can be easily injected into the organic semiconductor layer 19a from the source electrode 14a and the drain electrode 14b, and a large current can flow through the organic thin film transistor 1B. .

For example, when C60 fullerene (LUMO level: about 4.5 eV) is adopted as the material of the n-type organic semiconductor layer 19a, the material of the source electrode 14a and the drain electrode 14b is Al (work function: about 4.3 eV). ) Can be adopted. In this case, since the electron injection barrier height is small (about −0.2 eV), electrons can be easily injected from the source electrode 14a and the drain electrode 14b into the organic semiconductor layer 19a, which is large in the organic thin film transistor 1B. Current can flow.

Further, in order to increase the amount of carriers injected from the source electrode 14a and the drain electrode 14b to the organic semiconductor layer 19a, a thin oxide film layer of about several nm is formed between the source electrode 14a and the drain electrode 14b and the organic semiconductor layer 19a. May be.

24A, 24B, 25A, and 25B show the first and second steps of forming the body electrode of the thin film transistor substrate shown in FIGS. 19A and 19B. FIG. As shown in FIGS. 24A and 24B and FIGS. 25A and 25B, in the first step and the second step of forming the body electrode 17a, the thin film transistor according to the first embodiment is manufactured. The body electrode 17a whose tip is in contact with the upper surface of the organic semiconductor layer 19a is formed by performing a process substantially similar to the method. Thereby, the organic thin-film transistor 1B which concerns on this Embodiment can be manufactured.

For example, copper phthalocyanine (HOMO level: about 5.0 eV) is adopted as the material of the p-type organic semiconductor layer 19a, and Au (work function: about 5.0 eV) is adopted as the material of the source electrode 14a and the drain electrode 14b. In this case, Ca (work function: about 2.9 eV) can be adopted as the material of the body electrode 17a.

In this case, since the work function (about 2.9 eV) of the body electrode 17a is lower than the LUMO level (about 3.5 eV) of the organic semiconductor layer, the electrons accumulated in the organic semiconductor layer 19a are transferred to the body electrode 17a. Can be easily removed from the side. As a result, in the organic thin film transistor 1B according to the present embodiment, stable TFT characteristics can be realized while suppressing a shift in TFT characteristics during light irradiation or light OFF.

For example, C60 fullerene (HOMO level: about 6.2 eV, LUMO level: about 4.5 eV) is adopted as the material of the n-type organic semiconductor layer 19a, and Al (work function :) is used as the material of the source electrode 14a and the drain electrode 14b. When adopting about 4.3 eV), Pt (work function: about 5.7 eV) can be adopted as the material of the body electrode 17a.

In this case, since the work function (about 5.7 eV) of the body electrode 17a is close to the HOMO level (about 6.2 eV) of the organic semiconductor layer 19a, the holes accumulated in the organic semiconductor layer 19a are used as the body electrode. It can be easily extracted from the 17a side. As a result, in the organic thin film transistor 1B according to the present embodiment, stable TFT characteristics can be realized while suppressing a shift in TFT characteristics during light irradiation or light OFF.

Further, in order to enhance extraction of carriers from the organic semiconductor layer 19a to the body electrode 17a, a thin oxide film layer of about several nm may be formed between the body electrode 17a and the organic semiconductor layer 19a.

26 (A), (B) and FIGS. 27 (A), (B) show the first step of forming the interlayer protective layer and interlayer mask layer of the thin film transistor substrate shown in FIGS. 19 (A), (B). It is a figure which shows a 2nd process. 28A and 28B are diagrams showing a process of forming the pixel electrode, source electrode terminal, and body electrode terminal of the thin film transistor substrate shown in FIGS. 19A and 19B.

As shown in FIGS. 26A and 26B to FIGS. 28A and 28B, the step of forming the interlayer protective layer 22 and the interlayer mask layer 23A, the pixel electrode 25b, the source electrode terminal 25a, and the body electrode In the step of forming the terminals, the thin film transistor substrate 2B including the organic thin film transistor 1B having the bottom gate-top contact structure can be manufactured by performing substantially the same process as the manufacturing method of the thin film transistor substrate according to the first embodiment. .

In the organic thin film transistor 1B according to the present embodiment and the thin film transistor substrate 2B including the organic thin film transistor 1B, the body electrode 17a is formed of a material different from that of the source electrode 14a and the drain electrode 14b, thereby forming the source electrode 14a and the drain electrode 14b. The work function and the work function of the body electrode 17a are different.

With such a configuration, charges (electrons or holes) accumulated in the organic semiconductor layer 19a can be easily removed via the body electrode 17b. As a result, a stable TFT characteristic can be realized by suppressing a shift of the TFT characteristic at the time of light irradiation or light OFF, and this is also implemented in the organic thin film transistor 1B according to the present embodiment and the thin film transistor substrate 2B having the same. The same effects as those of the organic thin film transistor 1 according to the first embodiment and the thin film transistor substrate 2 including the same are obtained.

Further, in the method of manufacturing the thin film transistor substrate 2B according to the present embodiment, the source electrode 14a and the drain electrode 14b are formed after the organic semiconductor layer 19a is formed, so that the organic semiconductor film 19 is applied and baked. The source electrode 14a and the drain electrode 14b can be prevented from being oxidized. As a result, in the method of manufacturing the thin film transistor substrate 2B according to the present embodiment, the contact resistance defect can be reduced, and at the same time, the options for the source electrode and the drain electrode can be expanded.

(Embodiment 4)
29A and 29B are a cross-sectional view and a body electrode extending direction when a thin film transistor substrate including the organic thin film transistor according to the fourth embodiment is divided along the direction in which the source electrode and the drain electrode are arranged. It is sectional drawing at the time of dividing along. With reference to FIGS. 29A and 29B, an organic thin film transistor 1C according to the present embodiment and a thin film transistor substrate 2C including the same will be described. Note that FIG. 29A illustrates a portion corresponding to FIG. 2A, and FIG. 29B illustrates a portion corresponding to FIG. 2B.

As shown in FIGS. 29A and 29B, the organic thin film transistor 1C according to the present embodiment and the thin film transistor substrate 2C having the same are the organic thin film transistor 1B according to the third embodiment and the thin film transistor substrate 2B having the same. Is different in that the body electrode 17b has a work function different from that of the source electrode and the drain electrode by subjecting the body electrode 17b to a surface treatment, and the other configurations are substantially the same. .

Specifically, the source electrode 14a, the drain electrode 14b, and the body electrode 17b are made of the same metal material, and a self-assembled monolayer 93 is formed at the interface between the body electrode 17b and the organic semiconductor layer 19a. Has been. Even when the source electrode 14a, the drain electrode 14b, and the body electrode 17b are made of the same metal material, the source electrode 14a and the self-assembled monolayer 93 are formed so as to cover the surface of the body electrode 17b. The work function of the drain electrode 14b and the work function of the body electrode 17b can be made different.

Note that materials similar to those in the second embodiment can be employed as the material for the source electrode 14a, the drain electrode 14b, and the body electrode 17b, the material for the organic semiconductor layer 19a, and the material for the self-assembled monolayer.

The method of manufacturing the thin film transistor substrate 2C according to the present embodiment basically conforms to the method of manufacturing the thin film transistor substrate 2B according to the third embodiment, and has a surface treatment process, and thus the thin film transistor substrate according to the third embodiment. It is different from the manufacturing method of 2B.

In the method of manufacturing the thin film transistor substrate 2C according to the present embodiment, first, in the step of forming the base coat layer, the step of forming the gate electrode, the step of forming the gate insulating layer, and the step of forming the organic semiconductor layer The base coat layer 11, the gate electrode 12, the gate insulating layer 13, and the organic semiconductor layer 19 a are formed on the substrate 10 by performing the same process as in the method for manufacturing the thin film transistor substrate according to the third embodiment.

30 (A) and 30 (B) are diagrams showing a process of forming the source electrode, the drain electrode, and the body electrode of the thin film transistor substrate shown in FIGS. 29 (A) and 29 (B). As shown in FIGS. 30A and 30B, a source electrode 14a, a drain electrode 14b, and a body electrode 17b patterned in a predetermined shape by a vacuum deposition method, a sputtering method, or the like are formed with a thickness of about 100 to 400 nm. To do.

When the source electrode 14a, the drain electrode 14b, and the body electrode 17b are formed by the sputtering method, after forming the source / drain / body electrode film on the entire substrate 10 on which the organic semiconductor layer 19a is formed, the source / drain / body electrode film is formed. A photosensitive resist is applied on the drain / body electrode film. Thereafter, the photosensitive resist is patterned by photolithography (exposure / development). Subsequently, the source electrode 14a, the drain electrode 14b, and the body electrode 17b are patterned by wet etching or dry etching of the gate electrode film using the photosensitive resist as a mask.

Thereby, the source electrode 14a and the drain electrode 14b that are in contact with the end of the upper surface of the organic semiconductor layer 19a, respectively, and the body electrode 17b whose tip is in contact with the upper surface of the organic semiconductor layer 19a are formed.

For example, when copper phthalocyanine (HOMO level: about 5.0 eV) is adopted as the material of the p-type organic semiconductor layer 19a, the material of the source electrode 14a, the drain electrode 14b, and the body electrode 17b is Au (work function: About 5.0 eV) can be employed. In this case, since there is almost no hole injection barrier, holes can be easily injected into the organic semiconductor layer 19a from the source electrode 14a and the drain electrode 14b, and a large current can flow through the organic thin film transistor 1C. .

For example, when C60 fullerene (LUMO level: about 4.5 eV) is adopted as the material of the n-type organic semiconductor layer 19a, the material of the source electrode 14a, the drain electrode 14b, and the body electrode 17b is Au (work function: About 5.0 eV) can be employed. In this case, since the electron injection barrier height is small (about 0.5 eV), electrons can be easily injected into the organic semiconductor layer 19a from the source electrode 14a and the drain electrode 14b, and a large current flows into the organic thin film transistor 1C. Can flow.

FIGS. 31 (A) and 31 (B) are views showing a step of performing surface treatment on the body electrode shown in FIGS. 30 (A) and 30 (B). As shown in FIGS. 31A and 31B, in the step of subjecting the body electrode 17b to the surface treatment, by performing substantially the same treatment as that of the thin film transistor substrate according to the second embodiment, A self-assembled monolayer 93 is formed so as to cover the surface. As the self-assembled monolayer 93, the same material as that in Embodiment 2 can be used.

For example, when copper phthalocyanine is adopted as the p-type organic semiconductor material and Au is adopted as the material of the source electrode 14a, the drain electrode 14b and the body electrode 17b, MBT is applied on the surface of the body electrode 17b, The work function of the body electrode (Au) can be reduced from about 5.0 eV to about 4.3 eV.

Alternatively, as another example, when pentacene is adopted as the p-type organic semiconductor material and Cu is adopted as the material of the source electrode 14a, the drain electrode 14b, and the body electrode 17b, MBT is placed on the surface of the body electrode 17b. By applying, the work function of the body electrode (Cu) can be reduced from 4.7 eV to about 4.0 eV.

Since the work function of the body electrode 17b can be reduced to a value close to the LUMO level (about 3.5 eV) of copper phthalocyanine which is the p-type organic semiconductor layer 19a, the work function of the body electrode 17b is introduced into the organic semiconductor layer 19a via the body electrode 17b. Accumulated electrons can be easily extracted. As a result, in the organic thin film transistor 1C according to the present embodiment, stable TFT characteristics can be realized by suppressing a shift in TFT characteristics during light irradiation or light OFF.

Alternatively, as another example, when C60 fullerene is used as the n-type organic semiconductor material and Al is used as the material of the source electrode 14a, the drain electrode 14b, and the body electrode 17b, HBT or FBT is used for the body electrode 17b. By applying to the surface, the work function of the body electrode (Al) can be increased from 4.3 eV to 4.5 eV.

Since the work function of the body electrode 17b can be brought close to the HOMO level (about 6.2 eV) of C60 fullerene, which is the n-type organic semiconductor layer 19a, the work function is accumulated in the organic semiconductor layer 19a via the body electrode 17b. Holes can be easily extracted. As a result, in the organic thin film transistor 1C according to the present embodiment, stable TFT characteristics can be realized by suppressing a shift in TFT characteristics during light irradiation or light OFF.

Subsequently, in the step of forming the interlayer protective layer 22 and the interlayer mask layer 23A and the step of forming the pixel electrode 25b, the source electrode terminal 25a, and the body electrode terminal 25c, the same method as the method of manufacturing the thin film transistor substrate 2 according to the first embodiment. By performing this process, the thin film transistor substrate 2C including the organic thin film transistor 1C having the bottom gate-top contact structure can be manufactured.

In the organic thin film transistor 1C according to the present embodiment and the thin film transistor substrate 2C including the same, after the source electrode 14a, the drain electrode 14b, and the body electrode 17b are formed of the same material, the surface is formed only on the surface of the body electrode 17b. By performing the treatment, the work functions of the source electrode 14a and the drain electrode 14b are different from the work function of the body electrode 17a.

With such a configuration, charges (electrons or holes) accumulated in the organic semiconductor layer 19a can be easily removed via the body electrode 17b. As a result, a stable TFT characteristic can be realized by suppressing the shift of the TFT characteristic at the time of light irradiation or light OFF, and the organic thin film transistor 1C according to the present embodiment and the thin film transistor substrate 2C having the same are also implemented. Effects substantially similar to those of the organic thin film transistor 1B according to the third embodiment and the thin film transistor substrate 2B including the same are obtained.

Further, in the method of manufacturing the thin film transistor substrate 2C according to the present embodiment, the body electrode 17b can be formed with the same material as the source electrode 14a and the drain electrode 14b, thereby reducing the number of steps and material cost, Manufacturing cost can be reduced.

(Embodiment 5)
32A and 32B are cross-sectional views when the thin film transistor substrate including the organic thin film transistor according to the fifth embodiment is divided along the direction in which the source electrode and the drain electrode are arranged, and in the extending direction of the body electrode. It is sectional drawing at the time of dividing along. With reference to FIGS. 32A and 32B, an organic thin film transistor 1D according to the present embodiment and a thin film transistor substrate 2D including the same will be described. 32A shows a portion corresponding to FIG. 2A, and FIG. 32B shows a portion corresponding to FIG. 2B.

As shown in FIGS. 32A and 32B, the organic thin film transistor 1D according to the present embodiment and the thin film transistor substrate 2D having the same are the organic thin film transistor 1 according to the first embodiment and the thin film transistor substrate 2 having the same. Is different from the bottom gate-bottom contact structure in that it is a top gate-bottom contact structure, and the other configurations are substantially the same.

Specifically, the organic thin film transistor 1D according to the present embodiment includes a substrate 10, a base coat layer 11 formed so as to cover the main surface of the substrate 10, and a source disposed on the base coat layer 11 so as to be separated from each other. The base coat layer 11 located between the electrode 14a and the drain electrode 14b, the body electrode 17a disposed on the base coat layer 11 separately from the source electrode 14a and the drain electrode 14b, and the source electrode 14a and the drain electrode 14b. And an organic semiconductor layer 19a in contact with at least a part of the upper surface of each of the source electrode 14a, the drain electrode 14b, and the body electrode 17a.

The organic thin film transistor 1D includes a base coat layer 11 so as to cover the first protective layer 20a and the mask layer 21A provided to overlap the organic semiconductor layer 19a, and the mask layer 21A, the source electrode 14a, the drain electrode 14b, and the body electrode 17a. The second protective layer 30 provided above, the gate insulating layer 13 provided so as to cover the second protective layer 30, and the organic semiconductor layer 19a provided on the gate insulating layer 13 so as to face each other. And a gate electrode 12.

The source electrode 14a and the drain electrode 14b are provided so that at least a part thereof overlaps the gate electrode 12 with the gate insulating layer 13 interposed therebetween. The source electrode 14a and the drain electrode 14b are parts for allowing a current to flow through the organic semiconductor layer 19a.

The body electrode 17a is provided so as not to overlap the gate electrode 12. The body electrode 17a is a part for removing charges accumulated in the organic semiconductor layer 19a.

The thin film transistor substrate 2D according to the present embodiment includes an organic thin film transistor 1D, an interlayer protective layer 22 provided so as to cover the organic thin film transistor 1D, and an interlayer mask layer 23A provided so as to cover the interlayer protective layer 22. A source electrode terminal 25a connected to the source electrode 14a of the organic thin film transistor 1 through the contact hole 24a, a pixel electrode 25b connected to the drain electrode 14b of the organic thin film transistor 1 through the contact hole 24b, and a contact hole 24c. A body electrode terminal 25c connected to the body electrode 17a of the organic thin film transistor 1 via

Contact

holes

24a, 24b, and 24c are formed in the interlayer mask layer 23A, the interlayer protection layer 22, the gate insulating layer 13, and the second protection layer 30. The contact hole 24a is provided so as to reach the source electrode 14a from the surface side of the interlayer mask layer 23A. The contact hole 24b is provided so as to reach the drain electrode 14b from the surface side of the interlayer mask layer 23A. The contact hole 24c is provided so as to reach the body electrode 17a from the surface side of the interlayer mask layer 23A.

The manufacturing method of the thin film transistor substrate 2D according to the present embodiment basically conforms to the manufacturing method of the thin film transistor substrate according to the first embodiment, and before the step of forming the gate insulating layer and the step of forming the gate electrode. , And a step of forming a source electrode and a drain electrode, a step of forming a body electrode, a step of forming an organic semiconductor layer, a protective layer and a mask layer, and a step of forming a second protective film.

In the method of manufacturing the thin film transistor substrate 2D according to the present embodiment, first, in the step of forming the base coat layer, the substrate 10 is subjected to the same processing as the method of manufacturing the thin film transistor substrate according to the first embodiment. Base coat layer 11 is formed.

33 (A) and 33 (B) are diagrams showing a process of forming a source electrode and a drain electrode of the thin film transistor substrate shown in FIGS. 32 (A) and 32 (B). As shown in FIGS. 33A and 33B, in the step of forming the source electrode and the drain electrode, a process substantially similar to the method for manufacturing the thin film transistor substrate according to Embodiment 1 is performed, so that the base coat layer 11 is formed. A source electrode 14a and a drain electrode 14b that are spaced apart from each other are formed.

34A and 34B and FIGS. 35A and 35B show the first step and the second step of the step of forming the body electrode of the thin film transistor substrate shown in FIGS. 32A and 32B. FIG. As shown in FIGS. 34A and 34B and FIGS. 35A and 35B, in the first and second steps of forming the body electrode, the thin film transistor substrate according to the first embodiment is manufactured. A body electrode 17a separated from the source electrode 14a and the drain electrode 14b is formed on the base coat layer 11 by performing a process substantially similar to the method. This step is different from Embodiment 1 in that a photosensitive resist 15 is applied on the main surface of the base coat layer 11 so as to cover the source electrode 14a and the drain electrode 14b.

Further, in order to improve the adhesion between the base coat layer 11 and the source electrode 14a and drain electrode 14b, an adhesion layer such as Ti or Cr may be formed between the base coat layer 11 and the source electrode 14a and drain electrode 14b. .

36 (A), (B) and FIGS. 37 (A), (B) are steps for forming the organic semiconductor layer, the first protective layer, and the mask layer of the thin film transistor substrate shown in FIGS. 32 (A), (B). It is a figure which shows the 1st process and 2nd process. As shown in FIGS. 36A and 36B and FIGS. 37A and 37B, in the step of forming the organic semiconductor layer, the first protective layer, and the mask layer, the organic semiconductor in the first embodiment is used. The base coat layer 11 located between the source electrode 14a and the drain electrode 14b is covered by performing substantially the same process as the step of forming the layer, the protective layer, and the mask layer, and the source electrode 14a and the drain electrode 14b are covered. Then, an organic semiconductor layer 19a in contact with at least a part of the upper surface of each of the body electrodes 17a, a first protective layer 20a and a mask layer 21A formed so as to overlap the organic semiconductor layer 19a are formed.

38 (A) and 38 (B) are diagrams showing a process of forming the second protective layer and the gate insulating layer of the thin film transistor substrate shown in FIGS. 32 (A) and 32 (B). As shown in FIGS. 38A and 38B, in the step of forming the second protective layer 30 and the gate insulating layer 13, first, the organic semiconductor layer 19a, the first protective layer 20a, and the mask layer 21A are formed. A second protective layer 30 made of an inorganic insulating film, an organic insulating film, or a combination film of these is formed on the entire formed substrate by using a spin coating method, a slit coating method, an ink jet method, a printing method, or the like. To do. As a material for forming the second protective layer 30, a nitride film, an oxide film, a nitrided oxide film or the like can be adopted as the inorganic insulating film, and a CYTOP manufactured by Parylene, Asahi Glass Co., Ltd. can be used as the organic insulating film. (Registered trademark) or the like can be adopted. Note that the step of forming the second protective layer 30 may be omitted.

Subsequently, surface treatment such as atmospheric pressure plasma or oxygen plasma is performed on the entire surface of the substrate, and then the second protective layer 30 is formed by using a spin coating method, a slit coating method, an ink jet method, a printing method, or the like. The gate insulating layer 13 is formed with a thickness of about 200 nm to 1000 nm by applying an organic insulating material such as polyvinylphenol (PVP) or polystyrene (PS) to the entire substrate and then baking it.

39 (A) and 39 (B) are diagrams showing a process of forming the gate electrode of the thin film transistor substrate shown in FIGS. 32 (A) and 32 (B). As shown in FIGS. 39A and 39B, in the step of forming the gate electrode, a process substantially similar to the method for manufacturing the thin film transistor substrate 2 according to the first embodiment is performed, so that the gate electrode 13 is formed. The gate electrode 12 is formed to face the organic semiconductor layer 19a. Thereby, the organic thin film transistor 1D according to the present embodiment is manufactured.

40 (A), (B) and FIGS. 41 (A), (B) show the first step of forming the interlayer protective layer and the interlayer mask layer of the thin film transistor substrate shown in FIGS. 32 (A), (B). It is a figure which shows a 2nd process. As shown in FIGS. 40A and 40B, in the first step of forming the interlayer protective layer 22 and the interlayer mask layer 23A, the same process as the method for manufacturing the thin film transistor according to the first embodiment is performed. Thus, the interlayer protection layer 22 is formed on the gate insulating layer 13 so as to cover the gate electrode 12, and the organic insulating film 23 for forming the interlayer mask layer 23 </ b> A is formed so as to cover the interlayer protection layer 22.

As the organic insulating film 23, for example, a negative type organic insulating film can be adopted. By exposing and developing the organic insulating film 23 other than the region where the

contact holes

24a, 24b, and 24c are formed, the contact is obtained. An interlayer mask layer 23A is formed in a region other than the region where the

holes

24a, 24b, and 24c are to be formed.

Subsequently, dry etching is performed using the interlayer mask layer 23A as a mask, and as shown in FIGS. 41A and 41B, a contact hole penetrating the interlayer protective layer 22, the gate insulating layer 13, and the second protective layer 30 is formed. 24a, 24b, and 24c are formed.

42A and 42B are diagrams showing a process of forming a pixel electrode, a source electrode terminal, and a body electrode terminal of the thin film transistor substrate shown in FIGS. 32A and 32B. As shown in FIGS. 42A and 42B, the pixel electrode 25b, the source electrode terminal 25a, and the body electrode terminal 25c are formed by performing substantially the same process as the manufacturing method of the thin film transistor substrate 2 according to the first embodiment. Form.

Through the above steps, a thin film transistor substrate including the organic thin film transistor 1D having a top gate-bottom contact structure can be manufactured.

In the organic thin film transistor 1D according to the present embodiment, the same material as that of the first embodiment is adopted as the material of the source electrode 14a and the drain electrode 14b, the material of the body electrode 17a, and the material of the organic semiconductor layer 19a. Can do.

When the organic semiconductor layer is p-type, the hole injection barrier height can be reduced by making the work function of the source electrode 14a close to the HOMO level of the organic semiconductor layer 19a. For this reason, holes can be easily injected into the organic semiconductor layer 19a from the source electrode 14a and the drain electrode 14b, and a large current can flow in the organic thin film transistor 1D.

In addition, since the work function of the body electrode 17a is lower than the LUMO level of the organic semiconductor layer 19a, electrons accumulated in the organic semiconductor layer 19a can be easily extracted through the body electrode 17a.

When the organic semiconductor layer 19a is n-type, the electron injection barrier can be almost eliminated by bringing the work function of the source electrode 14a close to the LUMO level of the organic semiconductor layer 19a. For this reason, electrons can be easily injected from the source electrode 14a into the organic semiconductor layer 19a, and a large current can flow in the organic thin film transistor 1D.

Further, since the work function of the body electrode 17a is close to the HOMO level of the organic semiconductor layer 19a, holes accumulated in the organic semiconductor layer 19a can be easily extracted through the body electrode 17a.

As a result, in the organic thin film transistor 1D and the thin film transistor substrate 2D having the organic thin film transistor 1D according to the present embodiment, the light is irradiated or light is turned off regardless of whether the organic semiconductor layer 19a is p-type or n-type. Stable TFT characteristics can be realized by suppressing a shift in TFT characteristics at the time.

Thereby, the organic thin film transistor 1D according to the present embodiment and the thin film transistor substrate 2D having the same can obtain substantially the same effects as the organic thin film transistor 1 according to the first embodiment and the thin film transistor substrate 2 having the same.

(Embodiment 6)
43A and 43B are a cross-sectional view and a body electrode extending direction when a thin film transistor substrate including the organic thin film transistor according to the sixth embodiment is divided along the direction in which the source electrode and the drain electrode are arranged. It is sectional drawing at the time of dividing along. With reference to FIGS. 43A and 43B, an organic thin film transistor 1E according to the present embodiment and a thin film transistor substrate 2E including the same will be described. 43A shows a portion corresponding to FIG. 2A, and FIG. 43B shows a portion corresponding to FIG. 2B.

As shown in FIGS. 43A and 43B, the organic thin film transistor 1E according to the present embodiment and the thin film transistor substrate 2E having the same are the organic thin film transistor 1D according to the fifth embodiment and the thin film transistor substrate 2D having the same. Is different in that a body electrode 17b having a work function different from that of the source electrode 14a and the drain electrode 14b is provided by subjecting the body electrode 17b to a surface treatment, and the other configurations are substantially the same. It is.

In addition, as the material of the source electrode 14a, the drain electrode 14b, and the body electrode 17b, the material of the organic semiconductor layer 19a, and the material of the self-assembled monolayer 93, the same materials as those in Embodiment 2 can be employed. .

The method for manufacturing the thin film transistor substrate 2E according to the present embodiment is basically in accordance with the method for manufacturing the thin film transistor substrate 2D according to the fifth embodiment, and has a surface treatment step, and thus the thin film transistor substrate according to the fifth embodiment. It is different from the 2D manufacturing method.

In the method of manufacturing the thin film transistor substrate 2E according to the present embodiment, first, in the step of forming the base coat layer, the same process as that of the method of manufacturing the thin film transistor substrate 2D according to the fifth embodiment is performed. The base coat layer 11 is formed.

44 (A) and 44 (B) are diagrams showing a process of forming a source electrode, a drain electrode, and a body electrode of the thin film transistor substrate shown in FIGS. 43 (A) and 43 (B). As shown in FIGS. 44A and 44B, a source electrode 14a, a drain electrode 14b, and a body electrode 17b patterned in a predetermined shape by a vacuum deposition method, a sputtering method, or the like are formed with a thickness of about 100 to 400 nm. To do. The source electrode 14a, the drain electrode 14b, and the body electrode 17b are made of the same material.

45 (A) and 45 (B) are diagrams showing a step of performing a surface treatment on the body electrode shown in FIGS. 43 (A) and 43 (B). As shown in FIGS. 45A and 45B, in the step of subjecting the body electrode 17b to the surface treatment, the body electrode 17b is subjected to substantially the same treatment as that of the thin film transistor substrate 2A according to the second embodiment. A self-assembled monolayer 93 is formed so as to cover the surface. Thereby, the work function of the body electrode 17b can be changed. The photosensitive resist 16 is applied on the base coat layer 11 on which the source electrode 14a, the drain electrode 14b, and the body electrode 17b are formed so that only the surface of the body electrode 17b is exposed.

Subsequently, the step of forming the organic semiconductor layer, the first protective layer and the mask layer, the step of forming the second protective layer and the gate insulating layer, the step of forming the gate electrode, the interlayer protective layer and the interlayer mask layer are formed. In the step of forming the pixel electrode, the source electrode terminal, and the body electrode terminal, the thin film transistor substrate according to the present embodiment is performed by performing the same process as the manufacturing method of the thin film transistor substrate 2D according to the fifth embodiment. 2E is formed.

Through the steps described above, the thin film transistor substrate 2E including the organic thin film transistor 1E having a top gate-bottom contact structure can be manufactured.

In the organic thin film transistor 1E according to the present embodiment and the thin film transistor substrate 2E having the same, after the source electrode 14a, the drain electrode 14b, and the body electrode 17b are formed of the same material, the surface is formed only on the surface of the body electrode 17b. By performing the treatment, the work functions of the source electrode 14a and the drain electrode 14b are different from the work function of the body electrode 17a.

As described above, as the material for the source electrode 14a, the drain electrode 14b, and the body electrode 17b, the material for the organic semiconductor layer 19a, and the material for the self-assembled monolayer 93, the same materials as those in the second embodiment are employed. be able to.

When the organic semiconductor layer 19a is p-type, the hole injection barrier height can be reduced by bringing the work function of the source electrode 14a close to the HOMO level of the organic semiconductor layer 19a. For this reason, holes can be easily injected into the organic semiconductor layer 19a from the source electrode 14a and the drain electrode 14b, and a large current can flow in the organic thin film transistor 1E.

Also, as the self-assembled monomolecular film 93, for example, MBT is applied on the surface of the body electrode 17b, so that the work function of the body electrode can be reduced to approach the LUMO level of the organic semiconductor layer 19a. Thereby, the electrons accumulated in the organic semiconductor layer 19a can be easily extracted through the body electrode 17a.

When the organic semiconductor layer 19a is n-type, the electron injection barrier can be almost eliminated by bringing the work function of the source electrode 14a close to the LUMO level of the organic semiconductor layer 19a. For this reason, electrons can be easily injected from the source electrode 14a into the organic semiconductor layer 19a, and a large current can flow in the organic thin film transistor 1E.

Also, as a self-assembled monomolecular film, for example, by applying HBT or FBT to the surface of the body electrode 17b, the work function of the body electrode can be increased to approach the HOMO level of the organic semiconductor layer 19a. Thereby, the holes accumulated in the organic semiconductor layer 19a can be easily extracted through the body electrode 17a.

As a result, in the organic thin film transistor 1E according to the present embodiment and the thin film transistor substrate 2E having the organic thin film transistor 1E, even when the organic semiconductor layer 19a is p-type or n-type, the light irradiation or light OFF is performed. Stable TFT characteristics can be realized by suppressing a shift in TFT characteristics at the time.

Thereby, the organic thin film transistor 1E according to the present embodiment and the thin film transistor substrate 2E having the same can obtain substantially the same effects as the organic thin film transistor 1D according to the fifth embodiment and the thin film transistor substrate 2D having the same.

Further, in the method of manufacturing the thin film transistor substrate according to the present embodiment, the body electrode 17b can be formed using the same material as the source electrode 14a and the drain electrode 14b. Cost can be reduced.

(Embodiment 7)
46A and 46B are a cross-sectional view when the thin film transistor substrate including the organic thin film transistor according to the seventh embodiment is divided along the direction in which the source electrode and the drain electrode are arranged, and in the extending direction of the body electrode. It is sectional drawing at the time of dividing along. With reference to FIGS. 46A and 46B, an organic thin film transistor 1F according to the present embodiment and a thin film transistor substrate 2F including the same will be described. 46A shows a portion corresponding to FIG. 2A, and FIG. 46B shows a portion corresponding to FIG. 2B.

As shown in FIGS. 46A and 46B, the organic thin film transistor 1F according to the present embodiment and the thin film transistor substrate 2F having the same are the organic thin film transistor 1D according to the fifth embodiment and the thin film transistor substrate 2D having the same. And the source electrode 14a and the drain electrode 14b are different in that the first protective layer 20a and the mask layer 21A are not formed. Other configurations are almost the same.

Specifically, the organic thin film transistor 1F according to the present embodiment includes a substrate 10, a base coat layer 11 formed so as to cover the main surface of the substrate 10, and an organic semiconductor layer 19a formed on the base coat layer 11. The source electrode 14a, the drain electrode 14b, and the body electrode 17a provided on the base coat layer 11 so as to be in contact with the end of the upper surface of the organic semiconductor layer 19a, and the organic semiconductor layer 19a, the source electrode 14a, the drain electrode 14b, and the body. A gate insulating layer 13 provided on the base coat layer 11 so as to cover the electrode 17a and a gate electrode 12 provided so as to face the organic semiconductor layer 19a with the gate insulating layer 13 interposed therebetween are provided.

The source electrode 14a and the drain electrode 14b are disposed so as to be separated from each other, and are provided so that at least a part thereof overlaps the gate electrode 12 with the gate insulating layer 13 interposed therebetween. The source electrode 14a and the drain electrode 14b are parts for allowing a current to flow through the organic semiconductor layer 19a.

The manufacturing method of the thin film transistor substrate 2F according to the present embodiment basically conforms to the manufacturing method of the thin film transistor substrate 2D according to the fifth embodiment, and is partially applied to the manufacturing method of the thin film transistor substrate 2B according to the third embodiment. The same applies. The manufacturing method of the thin film transistor substrate 2F according to the present embodiment includes a step of forming the organic semiconductor layer 19a before the step of forming the source electrode 14a and the drain electrode 14b, and a protective layer and a mask on the organic semiconductor layer 19a. The method is different from the method of manufacturing the thin film transistor substrate 2D according to the fifth embodiment in that the layer forming step is not provided.

In the method of manufacturing the thin film transistor substrate 2F according to the present embodiment, first, the base coat is applied to the substrate 10 by performing the same process as the method of manufacturing the thin film transistor substrate according to the fifth embodiment in the step of forming the base coat layer. Layer 11 is formed.

47 (A), (B) and FIGS. 48 (A), (B) show the first step and the second step in the step of forming the organic semiconductor layer of the thin film transistor substrate shown in FIGS. 46 (A), (B). FIG. 47 (A), (B) and FIGS. 48 (A), (B), substantially the same processing as the first step and the second step of the step of forming the organic semiconductor layer according to the third embodiment. As a result, an organic semiconductor layer 19 a patterned in an island shape is formed on the base coat layer 11.

49A, 49B, 50A, and 50B show the first step and the first step of forming the source electrode and the drain electrode of the thin film transistor substrate shown in FIGS. 46A and 46B. It is a figure which shows 2 processes. As shown in FIGS. 49A and 49B and FIGS. 50A and 50B, substantially the same as the first step and the second step in the step of forming the source electrode and the drain electrode according to the third embodiment. By performing this process, the source electrode 14a and the drain electrode 14b are formed on the base coat layer 11 so as to be separated from each other and in contact with the end portion of the upper surface of the organic semiconductor layer 19a.

51A and 51B and FIGS. 52A and 52B show the first step and the second step of forming the body electrode of the thin film transistor substrate shown in FIGS. 46A and 46B. FIG. As shown in FIGS. 51 (A), (B) and FIGS. 52 (A), (B), substantially the same processing as the first step and the second step of the step of forming the body electrode according to the third embodiment is performed. By applying, the body electrode 17a is formed on the base coat layer 11 so as to be separated from the source electrode 14a and the drain electrode 14b and so that a part of the tip is in contact with the upper surface of the organic semiconductor layer 19a.

53 (A) and 53 (B) are views showing a process of forming a gate insulating layer of the thin film transistor substrate shown in FIGS. 46 (A) and 46 (B). As shown in FIGS. 53A and 53B, an organic semiconductor layer 19a, a source electrode 14a, a drain electrode 14b, and a process similar to those in the step of forming the gate insulating layer according to the fifth embodiment are performed. Gate insulating layer 13 is formed on base coat layer 11 so as to cover body electrode 17a.

54 (A) and 54 (B) are views showing a process of forming the gate electrode of the thin film transistor substrate shown in FIGS. 46 (A) and 46 (B). As shown in FIGS. 54A and 54B, the organic semiconductor layer 19a is opposed to the gate insulating layer 13 by performing almost the same process as the step of forming the gate electrode according to the fifth embodiment. Thus, the gate electrode 12 is formed on the gate insulating layer 13. Thereby, the organic thin film transistor 1F according to the present embodiment is formed.

FIGS. 55A and 55B and FIGS. 56A and 56B show the first step of forming the interlayer protective layer and the interlayer mask layer of the thin film transistor substrate shown in FIGS. 46A and 46B. It is a figure which shows a 2nd process. FIGS. 57A and 57B are diagrams showing a process of forming a pixel electrode, a source electrode terminal, and a body electrode terminal of the thin film transistor substrate shown in FIG. As shown in FIGS. 55A and 55B to FIGS. 57A and 57B, the step of forming the interlayer protective layer and the interlayer mask layer according to the fifth embodiment, the pixel electrode, the source electrode terminal, and the body By performing substantially the same process as the step of forming the electrode terminals, the interlayer protective layer 22, the interlayer mask layer 23A, the pixel electrode 25b, the source electrode terminal 25a, and the body electrode terminal 25c are formed.

Through the above process, the thin film transistor substrate 2F including the organic thin film transistor 1F having a top gate-top contact structure can be manufactured.

In the organic thin film transistor 1F and the thin film transistor substrate 2F having the same according to the present embodiment, the body electrode 17a is formed of a material different from that of the source electrode 14a and the drain electrode 14b, thereby forming the source electrode 14a and the drain electrode 14b. The work function and the work function of the body electrode 17a are different.

In addition, the material similar to Embodiment 3 can be employ | adopted for the material of the source electrode 14a and the drain electrode 14b, the material of the body electrode 17a, and the material of the organic-semiconductor layer 19a.

With such a configuration, charges (electrons or holes) accumulated in the organic semiconductor layer 19a can be easily removed via the body electrode 17b. As a result, it is possible to realize a stable TFT characteristic by suppressing the shift of the TFT characteristic at the time of light irradiation or at the time of light OFF, and this embodiment can provide substantially the same effect as that of the third embodiment.

Further, in the method of manufacturing the thin film transistor substrate according to the present embodiment, the source electrode 14a and the drain electrode 14b are formed after the organic semiconductor layer 19a is formed. This can prevent the source electrode 14a and the drain electrode 14b from being oxidized when the organic semiconductor film 19 is applied and baked. As a result, in the method for manufacturing the thin film transistor substrate according to the present embodiment, contact resistance defects can be reduced, and at the same time, options for the source electrode and the drain electrode can be expanded.

(Embodiment 8)
58A and 58B are a cross-sectional view and a body electrode extending direction when a thin film transistor substrate including the organic thin film transistor according to the eighth embodiment is divided along the direction in which the source electrode and the drain electrode are arranged. It is sectional drawing at the time of dividing along. With reference to FIGS. 58A and 58B, an organic thin film transistor 1G according to the present embodiment and a thin film transistor substrate 2G including the same will be described. 58A shows a portion corresponding to FIG. 2A, and FIG. 58B shows a portion corresponding to FIG. 2B.

As shown in FIGS. 58A and 58B, the organic thin film transistor 1G according to the present embodiment and the thin film transistor substrate 2G having the same are the organic thin film transistor 1F according to the seventh embodiment and the thin film transistor substrate 2F having the same. When the body electrode 17b is subjected to a surface treatment, the body electrode 17b has a work function different from that of the source electrode 14a and the drain electrode 14b. It is the same.

Specifically, the source electrode 14a, the drain electrode 14b, and the body electrode 17b are made of the same metal material, and a self-assembled monolayer 93 is formed at the interface between the body electrode 17b and the organic semiconductor layer 19a. Has been. Even when the source electrode 14a, the drain electrode 14b, and the body electrode 17b are made of the same metal material, the source electrode 14a and the drain are formed by forming the self-assembled monolayer so as to cover the surface of the body electrode 17b. The work function of the electrode 14b and the work function of the body electrode 17b can be made different.

In addition, as the material of the source electrode 14a, the drain electrode 14b, and the body electrode 17b, the material of the organic semiconductor layer 19a, and the material of the self-assembled monolayer 93, the same materials as those in Embodiment 4 can be employed. .

The manufacturing method of the thin film transistor substrate 2G according to the present embodiment basically conforms to the manufacturing method of the thin film transistor substrate 2F according to the seventh embodiment, and is partially applied to the manufacturing method of the thin film transistor substrate 2C according to the fourth embodiment. It conforms. The manufacturing method of the thin film transistor substrate 2G according to the present embodiment is different from the manufacturing method of the thin film transistor substrate 2F according to the seventh embodiment in that it includes a surface treatment process.

In the manufacturing method of the thin film transistor substrate 2G according to the present embodiment, first, in the step of forming the base coat layer and the step of forming the organic semiconductor layer, substantially the same as the manufacturing method of the thin film transistor substrate 2F according to the seventh embodiment. By performing the treatment, the base coat layer 11 and the organic semiconductor layer 19a are formed on the substrate 10.

FIGS. 59A and 59B are diagrams showing a process of forming a source electrode, a drain electrode, and a body electrode of the thin film transistor substrate shown in FIGS. 58A and 58B. As shown in FIGS. 59A and 59B, a source electrode 14a, a drain electrode 14b, and a body electrode 17b that are patterned into a predetermined shape by a vacuum deposition method, a sputtering method, or the like are formed with a thickness of about 100 to 400 nm. To do. The source electrode 14a, the drain electrode 14b, and the body electrode 17b are made of the same material.

60 (A) and 60 (B) are diagrams showing a process of performing a surface treatment on the body electrode shown in FIGS. 59 (A) and 59 (B). As shown in FIGS. 60A and 60B, in the step of subjecting the body electrode 17b to the surface treatment, the body electrode 17b is subjected to substantially the same treatment as that of the thin film transistor substrate 2C according to the fourth embodiment. A self-assembled monolayer 93 is formed so as to cover the surface. Thereby, the work function of the body electrode 17b can be changed. The photosensitive resist 29 is applied on the base coat layer 11 so that the surface of the body electrode 17b is exposed.

Subsequently, the step of forming the organic semiconductor layer, the first protective layer and the mask layer, the step of forming the second protective layer and the gate insulating layer, the step of forming the gate electrode, the interlayer protective layer and the interlayer mask layer are formed. In the step of forming the pixel electrode, the source electrode terminal, and the body electrode terminal, the thin film transistor substrate according to the present embodiment is performed by performing the same process as the manufacturing method of the thin film transistor substrate 2F according to the seventh embodiment. 2G is formed.

Through the steps described above, the thin film transistor substrate 2G including the organic thin film transistor 1G having a top gate-top contact structure can be manufactured.

In the organic thin film transistor 1G and the thin film transistor substrate 2G including the organic thin film transistor 1G according to the present embodiment, after the source electrode 14a, the drain electrode 14b, and the body electrode 17b are formed of the same material, the surface is formed only on the surface of the body electrode 17b. By performing the treatment, the work functions of the source electrode 14a and the drain electrode 14b are different from the work function of the body electrode 17a.

As described above, as the material for the source electrode 14a, the drain electrode 14b, and the body electrode 17b, the material for the organic semiconductor layer 19a, and the material for the self-assembled monolayer 93, the same materials as those in the fourth embodiment are employed. be able to.

When the organic semiconductor layer 19a is p-type, the hole injection barrier height can be reduced by bringing the work function of the source electrode 14a close to the HOMO level of the organic semiconductor layer 19a. For this reason, holes can be easily injected from the source electrode 14a and the drain electrode 14b into the organic semiconductor layer 19a, and a large current can flow in the organic thin film transistor 1G.

When the organic semiconductor layer 19a is n-type, the electron injection barrier can be almost eliminated by bringing the work function of the source electrode 14a close to the LUMO level of the organic semiconductor layer 19a. For this reason, electrons can be easily injected from the source electrode 14a into the organic semiconductor layer 19a, and a large current can flow in the organic thin film transistor 1G.

Also, as the self-assembled monomolecular film 93, for example, HBT or FBT is applied to the surface of the body electrode 17b, so that the work function of the body electrode can be increased to approach the HOMO level of the organic semiconductor layer 19a. Thereby, the holes accumulated in the organic semiconductor layer 19a can be easily extracted through the body electrode 17a.

As a result, in the organic thin film transistor 1G according to the present embodiment and the thin film transistor substrate having the organic thin film transistor 1G, even when the organic semiconductor layer 19a is p-type or n-type, the light is irradiated or the light is turned off. Stable TFT characteristics can be realized by suppressing the TFT characteristic shift.

Thereby, the organic thin film transistor 1G according to the present embodiment and the thin film transistor substrate 2G having the same can obtain substantially the same effects as the organic thin film transistor 1F according to the seventh embodiment and the thin film transistor substrate 2F having the same.

(Embodiment 9)
FIG. 61 is a plan view of an organic thin film transistor according to the ninth embodiment. 62 is a diagram showing energy levels of the organic thin film transistor shown in FIG. An organic thin film transistor 1H according to the present embodiment will be described with reference to FIGS.

As shown in FIG. 61, when the organic thin film transistor 1H according to the present embodiment is compared with the organic thin film transistor 1 according to the first embodiment, the source electrode 14a, the drain electrode 14b, and the body electrode 17b are made of the same material. The source electrode 14a, the drain electrode 14b, and the body electrode 17b have the same work function, and the other configurations are substantially the same.

As shown in FIG. 62, even when the source electrode 14a, the drain electrode 14b, and the body electrode 17b are made of the same material and their work functions are the same, the body electrode 17b is applied to the source electrode 14a. By applying a voltage different from the first voltage, the charge accumulated in the organic semiconductor layer 19a can be extracted.

For example, when the organic semiconductor layer 19a is p-type and electrons are accumulated in the organic semiconductor layer 19a, a positive high voltage is applied to the body electrode 17b, so that electrons are extracted from the organic semiconductor layer 19a. Can be pulled out.

On the other hand, when the organic semiconductor layer 19a is n-type and holes are accumulated in the organic semiconductor layer 19a, a negative high voltage is applied to the body electrode 17b, so that holes are generated from the organic semiconductor layer 19a. Can be pulled out.

Thus, by applying a voltage higher than that of the source electrode 14a to the body electrode 17b, even if the work functions of the source electrode 14a, the drain electrode 14b, and the body electrode 17b are the same, the charge accumulated in the organic semiconductor layer 19a Can be pulled out. As a result, even in the organic thin film transistor 1H according to the present embodiment, a stable TFT characteristic can be realized by suppressing a shift of the TFT characteristic at the time of light irradiation or light OFF.

As described in the first to eighth embodiments, when the work function of the body electrode 17b is different from that of the source electrode 14a and the drain electrode 14b, a lower voltage is applied to the body electrode. Thus, charges can be easily extracted from the organic semiconductor layer 19a.

(Embodiment 10)
63 is a schematic sectional view showing a liquid crystal display device including the thin film transistor substrate shown in FIG. FIG. 64 is a diagram showing a first example of an equivalent circuit diagram of the liquid crystal display device shown in FIG. 63. A liquid crystal display device 100 according to the present embodiment will be described with reference to FIGS. In the present embodiment, the case where the organic thin film transistor 1 according to the first embodiment is used as a switching element in the liquid crystal display device 100 will be described as an example, but instead of the organic thin film transistor 1 according to the first embodiment. Any of the organic thin film transistors according to the second to ninth embodiments may be used as a switching element.

As shown in FIG. 63, the liquid crystal display device 100 according to the present embodiment includes a liquid crystal display panel 90 and a backlight unit 45 that irradiates light toward the liquid crystal display panel 90.

The liquid crystal display panel 90 is provided between the thin film transistor substrate 2 disposed on the backlight unit 45 side, the counter substrate 42 disposed to face the thin film transistor substrate 2, and the thin film transistor substrate 2 and the counter substrate 42. And a liquid crystal layer 43. The liquid crystal layer 43 is sealed between the thin film transistor substrate 2 and the counter substrate 42 by an annular sealing material (not shown) that bonds the thin film transistor substrate 2 and the counter substrate 42 to each other. The liquid crystal layer 43 is made of a nematic liquid crystal material having electro-optical characteristics.

The counter substrate 42 includes a transparent substrate 40 such as a glass substrate, a color filter layer 41 formed on the main surface disposed on the liquid crystal layer 43 side, and a common electrode (not shown) formed on the color filter layer 41. Including. An alignment film for aligning the liquid crystal constituting the liquid crystal layer 43 is provided on the common electrode. An alignment film (not shown) is also provided on the thin film transistor substrate 2 so as to cover the entire surface on the pixel electrode 25b side.

The backlight unit 45 includes a light source 44 that emits light toward the liquid crystal display panel 90. As the light source 44, an LED, a cold cathode tube, or the like can be employed.

As shown in FIG. 64, the thin film transistor substrate 2 has a plurality of scanning signal lines GL provided so as to extend in parallel to each other, and extend in parallel to each other in a direction intersecting the scanning signal lines GL. A plurality of video signal lines DL provided and a plurality of constant potential lines VL provided so as to extend in parallel with the video signal lines DL are disposed between the adjacent video signal lines DL. Yes. In addition, auxiliary capacitance lines (not shown) are arranged between the adjacent scanning signal lines GL so as to extend in parallel with the scanning signal lines GL.

The organic thin film transistor 1 is provided in the vicinity of a portion where the plurality of scanning signal lines GL and the plurality of video signal lines DL intersect, and the organic thin film transistor 1 is provided for each pixel. The gate electrode 12 (gate electrode G) of the organic thin film transistor 1 is connected to the scanning signal wiring GL. The source electrode 14a (source electrode S) of the organic thin film transistor 1 is connected to the video signal wiring DL. The drain electrode 14b (drain electrode D) of the organic thin film transistor 1 is connected to the pixel electrode 25b and the auxiliary capacitance electrode. The body electrode 17a (body electrode BD) of the organic thin film transistor 1 is connected to the constant potential wiring VL.

The liquid crystal display device 100 includes a vertical operation circuit 50, a horizontal drive circuit 51, and a constant potential power circuit 52. The vertical operation circuit 50 is connected to the scanning signal wiring GL via a gate terminal (not shown) provided at the end of the scanning signal wiring GL. The horizontal drive circuit 51 is connected to the video signal line DL via a source electrode terminal 25a provided at the end of the video signal line DL. The constant potential power circuit 52 is connected to the constant potential wiring VL via a body electrode terminal 25c provided at the end of the constant potential wiring VL. The vertical operation circuit 50, the horizontal drive circuit 51, and the constant potential power supply circuit 52 function as drive circuits that drive a plurality of pixels in units of pixels.

In the liquid crystal display device, in each pixel, when the scanning signal is sent from the vertical operation circuit 50 to the gate electrode G via the scanning signal wiring GL, and the organic thin film transistor 1 is turned on, the image from the horizontal driving circuit 51 is displayed. A signal is sent to the source electrode S through the video signal wiring DL, and a predetermined charge is written into the pixel electrode 25b through the organic semiconductor layer 19a and the drain electrode D.

At this time, a potential difference is generated between each pixel electrode of the thin film transistor substrate 2 and the common electrode of the counter substrate 42, and a liquid crystal layer 43 (liquid crystal capacitor of each pixel) and a charge storage capacitor (in parallel with the liquid crystal capacitor) A predetermined voltage is applied to the auxiliary capacitor Cs.

In the liquid crystal display device 100, the light transmittance of the liquid crystal layer 43 is adjusted by changing the alignment state of the liquid crystal layer 43 according to the magnitude of the voltage applied to the liquid crystal layer 43 in each pixel. As a result, an image is displayed on the liquid crystal display device 100.

When a p-type organic semiconductor layer is used as the organic semiconductor layer 19a included in the organic thin film transistor 1, a positive high voltage is applied to the body electrode via the constant potential wiring VL. Thereby, surplus electrons accumulated in the organic semiconductor layer 19a by light irradiation are sucked out from the constant potential wiring VL through the body electrode 17a.

On the other hand, when an n-type organic semiconductor layer is used as the organic semiconductor layer 19a included in the organic thin film transistor 1, a high negative voltage is applied to the constant potential wiring VL. Thereby, surplus holes accumulated in the organic semiconductor layer 19a by light irradiation are sucked out from the constant potential wiring VL through the body electrode 17a.

As described above, the liquid crystal display device 100 according to the present embodiment can realize a stable TFT characteristic by suppressing a shift of a threshold voltage during light irradiation or light OFF. As a result, the liquid crystal display device 100 can obtain a stable display quality that is not easily affected by light such as external light and backlight light.

Note that the scanning signal wiring GL is preferably formed of the same material as the gate electrode in the step of forming the gate electrode of the organic thin film transistor 1. The video signal line DL is preferably formed of the same material as the source electrode and the drain electrode in the step of forming the source electrode and the drain electrode of the organic thin film transistor 1. In the case where the body electrode is formed of a material different from that of the source electrode and the drain electrode, the constant potential wiring VL is preferably formed of the same material as the body electrode in the step of forming the body electrode. When the body electrode is formed of the same material, it is preferable that the source electrode, the drain electrode, and the body electrode are formed of the same material in the step of forming the source electrode, the drain electrode, and the body electrode.

(Embodiment 11)
FIG. 65 is a diagram showing a second example of an equivalent circuit diagram of the liquid crystal display device shown in FIG. 63. A liquid crystal display device 100A according to the present embodiment will be described with reference to FIG. When compared with the liquid crystal display device according to the tenth embodiment, the liquid crystal display device 100A according to the present embodiment does not include the constant potential power supply circuit and the constant potential wiring, and the body electrode 17a is connected to the auxiliary capacitance wiring. In other respects, the configuration is substantially the same.

Thus, even if the body electrode 17a is configured to have the same potential as the auxiliary capacitance electrode and the common electrode, the charges (electrons or holes) accumulated in the organic semiconductor layer 19a by the light irradiation pass through the body electrode 17a. Sucked out of the auxiliary capacity wiring. Thereby, even in the liquid crystal display device 100 according to the present embodiment, substantially the same effect as the liquid crystal display device 100 according to the tenth embodiment can be obtained. The body electrode 17a may be connected to the common electrode of the counter substrate 42.

(Embodiment 12)
66 is a schematic cross-sectional view showing a first embodiment of an organic EL display device including the thin film transistor substrate shown in FIG. FIG. 67 is a diagram showing a first example of an equivalent circuit diagram of the organic EL display device shown in FIG. An organic EL display device 200 according to the present embodiment will be described with reference to FIGS. 66 and 67. FIG. In the present embodiment, the case where the organic thin film transistor 1 according to the first embodiment is used as an organic thin film transistor for driving EL in the organic EL display device 200 will be described as an example. Instead of the thin film transistor 1, any one of the organic thin film transistors according to the second to ninth embodiments may be used as an organic thin film transistor for driving an EL.

As shown in FIG. 66, in the organic EL display device 200 according to the present embodiment, the thin film transistor substrate 2 on which the pixel electrode 25b corresponding to the anode electrode is formed and the pixels are partitioned and adjacent pixels are not short-circuited. A partition wall layer 31 provided on the thin film transistor substrate 2, an organic EL layer 32 provided on the pixel electrode 25b, a counter electrode 33 corresponding to a cathode electrode provided on the organic EL layer 32, and a counter electrode 33 A passivation layer 34 is provided so as to cover it, and a counter substrate 60 is disposed on the passivation layer 34.

The pixel electrode 25b corresponding to the anode electrode, the organic EL layer 32, and the counter electrode 33 corresponding to the cathode electrode constitute an organic light emitting diode OLED.

As the pixel electrode 25b, for example, in a bottom emission type organic EL display device, a transparent conductive film such as IZO, ITO, ZnO, or SnO can be used. On the other hand, in a top emission type organic EL display device, a reflective electrode such as Al, Al alloy, Ag or Ag alloy is used, or a transparent conductive film such as IZO or ITO is used as an upper layer, and Al, Al alloy or Ag is used as a lower layer. It is possible to use a laminated structure electrode in which reflective electrodes such as Ag alloy, Mo, and Cr are combined.

The organic EL layer 32 is configured by stacking a hole transport layer (HTL), an EL light emitting layer (EM), and an electron transport layer (ETL) in this order. As the hole transport layer (HTL), for example, triphenyldiamine (TPD) can be employed.

The EL light emitting layer (EM) is preferably configured to be capable of color display by a red light emitting layer, a blue light emitting layer, and a green light emitting layer. As the red light emitting layer, for example, tris (8-hydroxyquinoline) aluminum (Alq3) blended with DCJBT and rubrene can be employed. As the blue light emitting layer, for example, DPVBi doped with BCzVBi can be employed. As the green light emitting layer, for example, Alq3 doped with coumarin 540 can be employed. Moreover, as an electron carrying layer (ETL), Alq3 can be employ | adopted, for example.

As the counter electrode 33, for example, in a bottom emission type organic EL display device, a reflective electrode such as Al, Al alloy, Ag, or Ag alloy can be employed. On the other hand, in a top emission type organic EL display device, a transparent conductive film such as IZO, ITO, ZnO, SnO or a thin metal film such as Au, Ag, Mg, Mg—Ag is used (as a transparent counter electrode). Can be used. The passivation layer 34 is formed to prevent intrusion of moisture, oxygen, and the like. As materials, an inorganic film such as SiN, SiO ₂ , Al ₂ O ₃ , an organic film such as a resin, and a laminated film thereof are used. A combination of these can be used.

As the counter substrate 60, a glass substrate or a plastic substrate such as PEN, PES, or PET can be employed. The counter substrate 60 is bonded to the thin film transistor substrate on which the organic EL layer 32, the counter electrode 33, and the passivation layer 34 are formed with an adhesive or the like.

As shown in FIG. 67, the thin film transistor substrate 2 has a plurality of scanning signal lines GL provided so as to extend in parallel to each other, and extend in parallel to each other in a direction intersecting the scanning signal lines GL. A plurality of video signal lines DL provided and a plurality of anode current supply lines An provided between the adjacent video signal lines DL so as to extend in parallel to the video signal lines DL are provided. ing.

Of the region partitioned by the two adjacent scanning signal lines GL and the two adjacent video signal lines DL, the anode current supply line An and the video signal line DL positioned away from the anode current supply line An are provided. A region partitioned by is equivalent to a pixel.

In the pixel, an organic thin film transistor Ts for switching, a charge storage capacitor Cs, an organic thin film transistor Td for driving an EL (organic thin film transistor 1), and an organic light emitting diode OLED are formed.

The gate electrode G of the organic thin film transistor Ts is connected to the scanning signal wiring GL. The source electrode S of the organic thin film transistor Ts is connected to the video signal wiring. The drain electrode D of the organic thin film transistor Ts is connected to one end side of the charge storage capacitor Cs and the gate electrode 12 of the organic thin film transistor Td for driving EL.

The source electrode 14a and the body electrode 17a of the organic thin film transistor Td are connected to the anode current supply wiring An. The drain electrode 14b of the organic thin film transistor Td is connected to the anode electrode (pixel electrode 25b) of the organic light emitting diode OLED. The other end side of the charge storage capacitor Cs is connected to the anode current supply wiring An.

The organic EL display device 200 includes a vertical operation circuit 50, a horizontal drive circuit 51, and an anode power supply circuit 53. The vertical operation circuit 50 is connected to the scanning signal wiring GL via a gate terminal (not shown) provided at the end of the scanning signal wiring GL. The horizontal drive circuit 51 is connected to the video signal line DL via a source electrode terminal 25a provided at the end of the video signal line DL. The anode power supply circuit 53 is connected to the anode current supply wiring An via a terminal portion provided at the end of the anode current supply wiring An. The vertical operation circuit 50, the horizontal drive circuit 51, and the anode power supply circuit 53 function as a drive circuit that drives a plurality of pixels in units of pixels.

In each pixel, when the scanning signal is sent from the vertical operation circuit 50 to the gate electrode G of the switching organic thin film transistor Ts via the scanning signal wiring GL, the horizontal driving circuit 51 is turned on. The video signal is supplied to the source electrode S of the organic thin film transistor Ts through the video signal wiring DL.

The signal supplied to the source electrode S is held in the charge storage capacitor Cs. At this time, the holding voltage of the charge storage capacitor Cs is a voltage between the gate electrode 12 and the source electrode 14a of the EL driving organic thin film transistor Td. A constant current corresponding to the voltage between the gate electrode 12 and the source electrode 14a is supplied from the anode power supply circuit 53 to the organic light emitting diode OLED via the anode current supply wiring An and the organic thin film transistor Td for driving EL. As a result, the organic light emitting diode OLED emits light and an image is displayed on the organic EL display device 200.

When a p-type organic semiconductor layer is used as the organic semiconductor layer 19a included in the organic thin film transistor 1 (organic thin film transistor Td), the body electrode 17a is connected to the anode current supply wiring An, so that the organic semiconductor is irradiated by light irradiation. Excess electrons accumulated in the layer 19a are sucked out from the anode current supply wiring An through the body electrode 17a.

Thereby, the organic EL display device 200 according to the present embodiment can realize a stable TFT characteristic by suppressing a shift of a threshold voltage at the time of light irradiation or light OFF. As a result, in the organic EL display device 200, a stable display quality that is hardly affected by light such as external light or self-light emission can be obtained.

The organic EL display device 200 can be used for a display medium such as a display, and can be diverted to a light emitting device such as an illumination.

(Embodiment 13)
FIG. 68 is a diagram showing a second example of an equivalent circuit diagram of the organic EL display device shown in FIG. With reference to FIG. 68, an organic EL display device 200A according to the present embodiment will be described.

As shown in FIG. 68, when compared with the organic EL display device 200 according to the twelfth embodiment, the organic EL display device 200A according to the present embodiment includes a constant potential power supply circuit 54 and a constant potential wiring HL. The difference is that the body electrode 17a is connected to the constant potential wiring HL, and the other configurations are substantially the same.

A plurality of constant potential wirings HL are provided between the adjacent scanning signal wirings GL so as to extend in parallel to the scanning signal wirings GL.

When a p-type organic semiconductor layer is used as the organic semiconductor layer 19a included in the organic thin film transistor 1, a positive high voltage is applied to the body electrode via the constant potential wiring HL. Thereby, surplus electrons accumulated in the organic semiconductor layer 19a by light irradiation are sucked out from the constant potential wiring HL through the body electrode 17a. Since the constant potential wiring HL is a separate system from the anode current supply wiring An, it is possible to apply a voltage more suitable for extracting surplus electrons. Thereby, even in the organic EL display device 200A according to the present embodiment, an effect equal to or higher than that of the organic EL display device 200 according to the twelfth embodiment is obtained.

(Embodiment 14)
FIG. 69 is a diagram showing a third example of an equivalent circuit diagram of the organic EL display device shown in FIG. 66. With reference to FIG. 69, an organic EL display device 200B according to the present embodiment will be described.

In the organic EL display device 200B according to the present embodiment, when compared with the organic EL display device 200 according to the eleventh embodiment, the body electrode 17a of the organic thin film transistor Td is the cathode electrode (counter electrode 33) of the organic light emitting diode OLED. Or it is different in that it is connected to the cathode current supply wiring CA and in that the organic semiconductor layer 19a is formed of an n-type organic semiconductor layer, and the other configurations are substantially the same.

As described above, when an n-type organic semiconductor layer is used as the organic semiconductor layer 19a included in the organic thin film transistor 1, the body electrode 17a is connected to the cathode electrode (counter electrode 33) or the cathode current supply wiring CA. The excess holes accumulated in the organic semiconductor layer 19a by the light irradiation are sucked out from the cathode current supply wiring CA through the body electrode 17a. Thereby, even in the organic EL display device 200B according to the present embodiment, substantially the same effects as those of the organic EL display device 200 according to the twelfth embodiment are obtained.

(Embodiment 15)
FIG. 70 is a schematic cross-sectional view showing a second embodiment of the organic EL display device including the thin film transistor substrate shown in FIG. 71 is a diagram showing a first example of an equivalent circuit diagram of the organic EL display device shown in FIG. An organic EL display device 200C according to the present embodiment will be described with reference to FIGS.

The organic EL display device 200C according to the present embodiment differs from the organic EL display device 200 according to the twelfth embodiment in the configuration of the organic EL layer 36. Accordingly, the pixel electrode 25b is an anode electrode. The counter electrode 35 formed on the organic EL layer 36 functions not as a cathode electrode but as an anode electrode, and instead of the anode power supply circuit and the anode current supply wiring, the cathode power supply circuit 55 and the cathode current are used. The difference is that the supply wiring CA is provided, and the other configurations are substantially the same.

Specifically, the organic EL layer 36 is configured by laminating an electron transport layer (ETL), an EL light emitting layer (EM), and a hole transport layer (HTL) in this order.

Thereby, a reflective electrode such as Al, Al alloy, Ag, or Ag alloy can be employed as the material of the cathode electrode (pixel electrode 25b). As a material for the anode electrode (counter electrode 35), a transparent conductive film such as IZO, ITO, CNT, or graphene, or a thin metal film such as Au or Ag can be used (as a transparent counter electrode). Alternatively, an ink containing nanoparticles such as Au, Ag, Cu, Al, IZO, ITO, CNT, and graphene can be employed.

In the organic EL display device 200C according to the present embodiment, in each pixel, a scanning signal is sent from the vertical operation circuit 50 to the gate electrode G of the switching organic thin film transistor Ts via the scanning signal wiring GL. When the organic thin film transistor Ts is turned on, a video signal is supplied from the horizontal drive circuit 51 to the source electrode S of the organic thin film transistor Ts via the video signal wiring DL.

The signal supplied to the source electrode S is held in the charge storage capacitor Cs. At this time, the holding voltage of the charge storage capacitor Cs is a voltage between the gate electrode 12 and the source electrode 14a of the EL driving organic thin film transistor Td. A constant current corresponding to the voltage between the gate electrode 12 and the source electrode 14a is supplied from the anode electrode (counter electrode 35) to the organic light emitting diode OLED via the organic thin film transistor Td for driving EL. As a result, the organic light emitting diode OLED emits light and an image is displayed on the organic EL display device 200C.

In the present embodiment, any of a p-type semiconductor layer and an n-type semiconductor layer can be used as the organic semiconductor layer 19a included in the organic thin film transistor 1 (organic thin film transistor Td for driving EL), as shown in FIG. In particular, this is particularly effective when an n-type semiconductor layer is used. That is, even if the performance of the organic EL layer deteriorates due to long-term energization or moisture and the voltage at the anode end changes, the current between the gate electrode 12 and the source electrode 14a that determines the current flowing in the organic thin film transistor Td for driving the EL is changed. This is because the voltage is not affected, and a constant current can flow through the organic thin film transistor Td and the organic EL layer. Thereby, the organic EL display device 200C having uniform and stable luminance (display quality) is obtained.

When the n-type organic semiconductor layer is used, the body electrode 17a is connected to the cathode current supply wiring CA, so that excess holes accumulated in the organic semiconductor layer 19a due to light irradiation pass through the body electrode 17a. Sucked from the cathode current supply wiring CA. Thereby, the organic EL display device 200C according to the present embodiment can realize a stable TFT characteristic by suppressing a shift of a threshold voltage during light irradiation or light OFF. As a result, in the organic EL display device 200C, it is possible to obtain a stable display quality that is hardly affected by light such as external light or self-light emission.

In the above-described

Embodiments

2, 4, 6, and 8, the case where the surface treatment is performed only on the body electrode when the source electrode, the drain electrode, and the body electrode are made of the same material has been described as an example. The present invention is not limited to this, and even in the first, third, fifth, and seventh embodiments, the surface treatment may be performed only on the body electrode even when the body electrode is formed of a material different from that of the source electrode and the drain electrode.

In the above-described

Embodiments

2, 4, 6, and 8, the source electrode, the drain electrode, and the body electrode are made of the same metal material, and only the body electrode is subjected to a surface treatment, whereby the source electrode and the drain electrode are formed. However, the present invention is not limited to this, and the source electrode, the drain electrode, and the body electrode are made of the same metal material, and the n-type organic semiconductor layer and p The work function of the source and drain electrodes and the body electrode is formed by forming body electrodes having different surface orientations from the surface orientation of the source and drain electrodes, regardless of which type of organic semiconductor layer is used. May be adjusted.

Table 1 shows the work function for each plane orientation and the work function of polycrystalline in each electrode material. The value of the work function is a value disclosed in various documents and may vary depending on the experimental environment or the like, but is known to be approximately the value shown in Table 1 below.

For example, when pentacene is used as the p-type organic semiconductor material and Au is used as the material of the source electrode 14a, the drain electrode 14b, and the body electrode 17b, the plane orientation of the main surfaces of the source electrode 4a and the drain electrode 14b is mainly used. It is formed so as to be (100), and the surface orientation of the main surface of the body electrode 17b is mainly (110).

With this configuration, the work function of the body electrode 17b is approximately 4.8 eV, and the work function of the body electrode 17b is a value close to the LUMO level (about 3.5 eV) of pentacene, which is the p-type organic semiconductor layer 19a. Can be made smaller.

As a result, electrons accumulated in the organic semiconductor layer 19a can be easily extracted via the body electrode 17b. Thereby, stable TFT characteristics can be realized while suppressing a shift in TFT characteristics during light irradiation or light OFF.

For example, when C60 fullerene is adopted as the n-type organic semiconductor material and Au is adopted as the material of the source electrode 14a, the drain electrode 14b, and the body electrode 17b, the surfaces of the main surfaces of the source electrode 4a and the drain electrode 14b It is formed so that the orientation is mainly (100), and the surface orientation of the main surface of the body electrode 17b is mainly (111).

With this configuration, the work function of the body electrode 17b is approximately 5.3 eV, and the work function of the body electrode 17b is brought close to the HOMO level (about 6.2 eV) of the C60 fullerene that is the n-type organic semiconductor layer 19a. be able to.

As a result, holes accumulated in the organic semiconductor layer 19a can be easily extracted through the body electrode 17b. Thereby, stable TFT characteristics can be realized while suppressing a shift in TFT characteristics during light irradiation or light OFF.

Note that the materials of the source electrode 14a, the drain electrode 14b, and the body electrode 17b and their plane orientations are not limited to the above description, and are appropriately selected based on Table 1 within a range that does not depart from the spirit of the present invention. can do. Similarly, even when the material of the source and drain electrodes and the material of the body electrode are different, those materials and plane orientations can be appropriately selected based on Table 1.

As mentioned above, although embodiment of this invention was described, embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, and includes meanings equivalent to the terms of the claims and all changes within the scope.

1, 1A, 1B, 1C, 1D, 1F, 1G, 1H organic thin film transistor, 2, 2A, 2B, 2C, 2D, 2F, 2G thin film transistor substrate, 10 substrate, 11 base coat layer, 12 gate electrode, 13 gate insulating layer, 14 drain electrode film, 14a source electrode, 14b drain electrode, 15, 16, 26, 27, 28, 29 photosensitive resist, 17 body electrode film, 17a, 17b body electrode, 19 organic semiconductor film, 19a organic semiconductor layer, 20 Protective film, 20a protective layer, 21, 23 organic insulating film, 21A mask layer, 22 interlayer protective layer, 23A interlayer mask layer, 24a, 24b, 24c contact hole, 25a source electrode terminal, 25b pixel electrode, 25c body electrode terminal, 30 protective layers, 31 partition layers, 33, 3 Counter electrode, 34 passivation layer, 40 transparent substrate, 41 color filter layer, 42, 60 counter substrate, 43 liquid crystal layer, 44 light source, 45 backlight unit, 50 vertical operation circuit, 51 horizontal drive circuit, 52, 54 constant potential power supply Circuit, 53 anode power circuit, 55 cathode power circuit, 81, 82 shading mask, 81a, 82a opening, 90 liquid crystal display panel, 93 self-assembled monolayer, 100, 100A liquid crystal display, 200, 200A, 200B, 200C organic EL display.

Claims

A gate electrode;
An organic semiconductor layer disposed opposite to the gate electrode;
A gate insulating layer located between the gate electrode and the organic semiconductor layer;
A source electrode and a drain electrode connected to the organic semiconductor layer and configured to pass a current through the organic semiconductor layer;
An organic thin film transistor, comprising: a body electrode connected to the organic semiconductor layer and for removing charges accumulated in the organic semiconductor layer.
The organic thin film transistor according to claim 1, wherein the body electrode is made of a material different from that of the source electrode and the drain electrode.
The organic thin film transistor according to claim 1 or 2, wherein a monomolecular film is formed at an interface between the body electrode and the organic semiconductor layer.
The organic semiconductor layer is a p-type organic semiconductor layer,
The organic thin film transistor according to any one of claims 1 to 3, wherein a work function of the body electrode is smaller than a work function of the source electrode and the drain electrode.
The organic semiconductor layer is an n-type organic semiconductor layer,
4. The organic thin film transistor according to claim 1, wherein a work function of the body electrode is larger than work functions of the source electrode and the drain electrode. 5.