KR101450911B1 - Organic thin film transistor, manufacturing method thereof and display device - Google Patents

Abstract

Disclosed is an organic thin film transistor, a method of manufacturing the same, and a display device having the same.

A method for fabricating an organic thin film transistor according to the present invention includes the steps of: forming a buffer layer having hydrophobicity on a substrate; subjecting a predetermined region of the buffer layer to surface treatment to form a hydrophilic surface treatment layer; forming a source / Forming an organic semiconductor layer on the surface treatment layer, forming an organic insulating film on the organic semiconductor layer, and forming a gate electrode on the organic insulating film.

In the present invention, by forming the organic semiconductor layer only on the buffer layer having a hydrophilic property by surface-treating a part of the buffer layer, the conventional bank layer is not required and the process cost can be reduced and the process can be simplified.

Display device, organic thin film transistor, surface treatment, ultraviolet ray

Description

TECHNICAL FIELD The present invention relates to an organic thin film transistor, a method of manufacturing the same, and a display device having the organic thin film transistor.

The present invention relates to an organic thin film transistor, a method of manufacturing the same, and a display device having the same.

2. Description of the Related Art In recent years, attention has been paid to polymer materials as a new electrical and electronic material in a wide range of fields such as functional electronic devices and optical devices due to their ease of molding in a fiber or film form, flexibility, conductivity and low production cost.

Among the devices using such a polymer material, the organic thin film transistor has been actively studied because it can be easily manufactured by the ink jet method and has good advantages in processing and compatibility with a flexible substrate.

1 is a view showing a conventional organic thin film transistor.

A buffer layer 3 made of an inorganic material such as silicon nitride (SiN4) is formed on a substrate 1 and source / drain electrodes 5a and 5b are formed on the buffer layer 3 .

A pair of bank layers 7 made of an organic material such as photoacryl is formed adjacent to the outside of the source / drain electrodes 5a and 5b.

The organic semiconductor layer 9 is formed on the substrate 1 including the source electrode 5a and the drain electrode 5b between the pair of bank layers 7 and the organic insulating film 11 is formed thereon do.

When the organic semiconductor layer 9 is formed, the pair of the bank layers 7 is moved to another adjacent organic thin film transistor so that the organic semiconductor layer 9 is formed between the adjacent organic thin film transistors As shown in Fig.

A gate electrode 13 is formed on the organic insulating film 11.

As described above, in the conventional organic thin film transistor, since the bank layers are formed by using a photolithography process to prevent the organic semiconductor solution from being separated, a process is added to complicate the process and the process cost is increased.

The present invention relates to an organic thin film transistor in which an organic semiconductor solution is formed by localizing the organic semiconductor solution to a semiconductor formation region by using a surface treatment, thereby eliminating the need for a bank layer, thereby reducing the process cost and simplifying the process, And a display device.

According to the present invention, a method of manufacturing an organic thin film transistor includes: forming a buffer layer having hydrophobicity on a substrate; Forming a surface treatment layer having hydrophilicity by surface-treating a predetermined region of the buffer layer; Forming a source / drain electrode on the buffer layer; Forming an organic semiconductor layer on the surface treatment layer; Forming an organic insulating layer on the organic semiconductor layer; And forming a gate electrode on the organic insulating film.

According to the present invention, an organic thin film transistor includes: a buffer layer having hydrophobicity formed on a substrate; A hydrophilic surface treatment layer formed on a predetermined region of the buffer layer; Source / drain electrodes formed on the buffer layer; An organic semiconductor layer formed on the surface treatment layer; An organic insulating layer formed on the organic semiconductor layer; And a gate electrode formed on the organic insulating film.

According to the present invention, a display device includes: a plurality of gate lines; Data lines crossing the gate lines; An organic thin film transistor connected to each of the gate lines and the data lines; And a pixel electrode connected to the organic thin film transistor, wherein the organic thin film transistor includes: a buffer layer having hydrophobicity formed on a substrate; A hydrophilic surface treatment layer formed on a predetermined region of the buffer layer; Source / drain electrodes formed on the buffer layer; An organic semiconductor layer formed on the surface treatment layer; An organic insulating layer formed on the organic semiconductor layer; And a gate electrode formed on the organic insulating layer, wherein the pixel electrode is formed in contact with the drain electrode and the buffer layer.

According to the present invention, a method of manufacturing an organic thin film transistor includes: forming a gate electrode on a substrate; Forming a buffer layer having hydrophobicity on the gate electrode; Forming a source / drain electrode on the buffer layer; Forming a surface treatment layer having hydrophilicity by surface-treating a predetermined region of the buffer layer; Forming an organic semiconductor layer on the surface treatment layer; And forming an organic insulating layer on the organic semiconductor layer.

In the present invention, by forming the organic semiconductor layer only on the buffer layer having a hydrophilic property by surface-treating a part of the buffer layer, the conventional bank layer is not required and the process cost can be reduced and the process can be simplified.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

2 is a diagram showing a display device of the present invention.

Referring to FIG. 2, in the display device of the present invention, a plurality of pixels P are arranged in a matrix. The pixel P may be a red pixel, a green pixel, and a blue pixel.

The display device may be a liquid crystal display device, an organic light emitting display device, or an electrophoretic display device. When the substrate of the display device is used as a flexible material, for example, a plastic material, a glass material, or a stainless steel material, the display device can be used as a flexible display device.

In the display device of the present invention, a plurality of gate lines GL1 to GLn are arranged, and a plurality of data lines DL1 to DLm are arranged to cross the lines GL1 to GLn. The unit pixel P can be defined by each of the gate lines GL1 to GLn and each of the data lines DL1 to DLm. Therefore, the display device of the present invention can arrange such unit pixels P in a matrix.

The thin film transistor 20 may be connected to each of the gate lines GL1 to GLn and the data lines DL1 to DLm and the pixel electrode 28 or the driving electrode may be connected to the thin film transistor 20. [

The thin film transistor 20 of the present invention may be an organic thin film transistor formed by an organic semiconductor material.

3 is a cross-sectional view of the organic thin film transistor of FIG.

A buffer layer 24 made of organic material such as photoacryl having hydrophobic on the substrate 22 is disposed.

The substrate 22 may be made of a glass material for use in a liquid crystal display, an organic light emitting display, or an electrophoretic display.

Alternatively, the substrate 22 may be made of a thin-walled glass material, a plastic material, or a stainless steel material for use as a flexible display device.

Therefore, the hydrophobic buffer layer 24 can limit the spread of the organic semiconductor layer 30 to be disposed later.

The buffer layer 24 may have a surface treatment layer 24 'whose surface is hydrophilic only in the semiconductor formation region. To this end, the surface treatment can be performed on the surface of the semiconductor forming region in the buffer layer 24, which will be described later in detail.

Source / drain electrodes 26a and 26b made of a low resistance metal material such as gold (Au), copper (Cu), copper alloy, aluminum (Al), or aluminum alloy are disposed on the buffer layer 24. The data lines DL1 to DLm may be arranged together with the source / drain electrodes 26a and 26b. In the substrate 22 including the source / drain electrodes 26a and 26b, the organic semiconductor layer 30 is disposed on the surface treatment layer 24 'of the buffer layer 24 corresponding to the semiconductor formation region.

The pixel electrode 28 may be disposed on the pixel P in contact with the upper surface of the drain electrode 26b. The pixel electrode 28 may be made of a transparent conductive material such as indium-tin-oxide (ITO), indium-zinc-oxide (IZO), or indium-tin-zinc-oxide.

The pixel electrode 28 may be disposed not only on the pixel but also on the upper surface as well as the side surface of the drain electrode 26b. The pixel electrode 28 may be formed to directly contact the drain electrode 26b. In addition, the pixel electrode 26b may be formed to directly contact the buffer layer 24 in the pixel P.

The organic semiconductor layer 30 is disposed in the semiconductor formation region of the buffer layer 24. [ The organic semiconductor layer 24 has a buffer layer 24 corresponding to the semiconductor forming region because the surface of the buffer layer 24 corresponding to the semiconductor forming region has hydrophilicity and the other surfaces have hydrophobicity. Can be locally disposed only on the surface treatment layer 24 '.

The organic semiconductor layer 30 may include a source electrode 26a and may extend to a portion of the upper surface of the drain electrode 26b, that is, an end region of the pixel electrode 28. [

This is possible because the organic semiconductor material does not spread to the pixel electrode 28 since the pixel electrode 28 has hydrophobicity.

The organic semiconductor material may be a polymer organic semiconductor material or a low-molecular organic semiconductor material having relatively high mobility, for example, liquid phase pentacene or polythiophene.

An organic insulating material 32, for example, photoacryl or poly vinyl alcohol, is disposed on the organic semiconductor layer 30.

A gate electrode 34 made of a metal material such as molybdenum (Mo) or chromium (Cr) is formed on the organic insulating film 32. The gate lines GL1 to GLn may be further disposed together with the gate electrode 34. [

The gate lines GL1 to GLn are overlapped with a part of the pixel electrode 28, so that a storage capacitor can be formed.

The above organic thin film transistor is a top gate type. However, the present invention is not limited thereto, but may be applied to a bottom gate type in which a gate electrode is formed in the bottom layer.

A protective film (not shown) may be disposed on the gate electrode 34 and the organic insulating film 32 to protect the gate electrode 34 and the organic insulating film 32, if necessary.

An organic light emitting layer must be formed on the pixel electrode 28 so that the protective film disposed on the pixel electrode 28 of the pixel P can be opened to expose the pixel electrode 28. [

As described above, the present invention eliminates the need for the bank layer used in the related art, so that the thickness of the organic thin film transistor is reduced, thereby reducing the thickness of the display device.

4A to 4G are views showing the process of the organic thin film transistor of the present invention.

As shown in FIG. 4A, a buffer layer 24 is formed on the substrate 22 by over-depositing an organic material such as a photoacrylic material having hydrophobicity. Since the buffer layer 24 has hydrophobicity, the organic semiconductor material formed in the buffer layer 24 is not spread well due to the hydrophobicity of the buffer layer 24.

As shown in FIG. 4B, a first metal material is deposited on the buffer layer 24 and patterned using a mask to form source / drain electrodes 26a and 26b. The first metal material may be a low resistance metal material, for example, gold (Au), copper (Cu), copper alloy, aluminum (Al), or aluminum alloy. Since the buffer layer 24 has a good adhesion property with the first metal material, the first metal material can be formed on the buffer layer 24 with a strong adhesive force.

For use as a display device, data lines DL1 to DLm may be formed in addition to the source / drain electrodes 26a and 26b.

Subsequently, for use as a display device, a transparent conductive material is deposited and patterned with a mask to form a pixel electrode 28 in the pixel. Alternatively, the pixel electrode 28 may be formed on the upper surface and the side surface of the drain electrode 26b, and may be electrically connected to the drain electrode 26b.

The mask 50 is placed on the substrate 22 including the source / drain electrodes 26a and 26b and the pixel electrode 28 and irradiated with ultraviolet rays, as shown in Fig. 4C. The mask 50 includes a blocking region 50a for blocking ultraviolet rays and a transmitting region 50b for transmitting ultraviolet rays.

The transmissive region 50b of the mask 50 may correspond to a semiconductor formation region for forming an organic semiconductive layer on the substrate 22. [ Therefore, ultraviolet rays are transmitted through the transmission region 50b of the mask 50 and irradiated to the surface of the buffer layer 24 corresponding to the semiconductor formation region.

As shown in FIG. 4D, as a result of ultraviolet irradiation, the buffer layer 24 corresponding to the semiconductor formation region is surface-treated to form the surface treatment layer 24 'having hydrophilicity.

The principle of forming the surface treatment layer 24 'is to irradiate the organic material film 62 with ultraviolet rays, as shown in FIG. 5A. The organic material of the organic material film 62 may be composed of an organic compound (CmHnOk).

In this case, as shown in FIG. 5B, ozone (O 3) in the atmosphere is decomposed by ultraviolet rays to generate active corals (O 2). In addition, the organic compound (CmHnOk) of the organic material of the organic material film 62 is decomposed by ultraviolet rays.

Accordingly, the surface treatment layer 64, in which the surface of the organic material film 62 is changed from hydrophobic to hydrophilic, reacts with the decomposed organic compound (CmHnOk) to generate CO 2, H 2 O, CO, .

The wavelength of ultraviolet rays for decomposing ozone (O3) may be 253.7 nm.

According to the principle of the surface treatment layer, the surface treatment layer 24 'having the hydrophilic surface of the buffer layer 24 corresponding to the semiconductor formation region is formed.

As shown in FIG. 4E, the organic semiconductor solution 66 is dropped using the ink jet 64 on the substrate 22. Thus, the organic semiconductor solution 66 on the surface treatment layer 24 'is hydrophilic, so that the organic semiconductor solution 66 on the surface treatment layer 24' The organic semiconductor solution 66 on the buffer layer 24 except for the surface treatment layer 24 'is relatively easily sideways because the buffer layer 24 except for the surface treatment layer 24' has hydrophobicity, The organic semiconductor solution 66 is accumulated only on the surface treatment layer 24 'so that the round-type organic semiconductor solution film 60 is formed.

The organic semiconductor solution 66 may include at least a polymer organic semiconductor material or a low molecular organic semiconductor material such as pentacene or polythiophene.

The organic semiconductor solution film 60 is formed by irradiating heat or light to the substrate 22 and hardening or drying the organic semiconductor solution film 60 as shown in FIG. The organic semiconductor layer 30 is formed.

As shown in FIG. 4G, an organic insulating material is formed on the substrate 22 including the organic semiconductor layer 30 to form the organic insulating film 32. The organic flame retardant may be photoacryl or poly vinyl alcohol.

Then, a second metal material is deposited on the organic insulating film 32, and the gate electrode 34 is formed by patterning using a mask.

Gate lines GL1 to GLn may be formed in addition to the gate electrode 34 for use as a display device.

As described above, according to the present invention, the organic semiconductor layer is formed only on the buffer layer having hydrophilicity by surface-treating a part of the buffer layer, thereby eliminating the need for a conventional bank layer, .

The above organic thin film transistors are top gate type.

The present invention is not limited to this and can be applied to an organic thin film transistor of a botom gate type.

In a bottom gate type organic thin film transistor, a buffer layer having hydrophobicity is formed on a gate electrode, a source / drain electrode is formed on the buffer layer, and a surface treatment layer having hydrophilicity is formed on the semiconductor formation region by surface- The organic semiconductor layer can be formed. An organic insulating film may be formed on the organic semiconductor layer. In this case, as described above, the organic semiconductor layer can be locally formed in the surface treatment layer.

1 is a view showing a conventional organic thin film transistor.

2 is a diagram showing a display device of the present invention.

3 is a cross-sectional view of the organic thin film transistor of FIG.

4A to 4G are views showing the process of the organic thin film transistor of the present invention.

5A and 5B are views for explaining the principle of forming the surface treatment layer of the present invention.

Description of the Related Art

20: organic thin film transistor 22: substrate

24: buffer layer 24 'Surface treatment layer

26a: source electrode 26b: drain electrode

28: pixel electrode 30: organic semiconductor layer

32: organic insulating film 34: gate electrode

Claims (10)

Forming a buffer layer having hydrophobicity on the substrate; Forming a source / drain electrode on the buffer layer; Forming a surface treatment layer having hydrophilicity by surface-treating a predetermined region of the buffer layer; Forming an organic semiconductor layer on the surface treatment layer; Forming an organic insulating layer on the organic semiconductor layer; And And forming a gate electrode on the organic insulating layer. The method of claim 1, wherein the buffer layer is made of an organic material. The method according to claim 2, wherein forming the surface treatment layer comprises: Irradiating the predetermined region with ultraviolet light; Decomposing ozone into active oxygen by the ultraviolet rays and decomposing organic substances in the buffer layer; And And forming a surface treatment layer on the predetermined region by reacting the active oxygen with the decomposed organic material. 4. The method of claim 3, wherein the wavelength of the ultraviolet light is 253.7 nm. 4. The method of claim 3, wherein the ultraviolet light is irradiated to a buffer layer corresponding to the predetermined region by a mask. 6. The method of claim 5, wherein the predetermined region is a region where the organic semiconductor layer is formed. A buffer layer having hydrophobicity formed on the substrate; A hydrophilic surface treatment layer formed on a predetermined region of the buffer layer; Source / drain electrodes formed on the buffer layer; An organic semiconductor layer formed on the surface treatment layer; An organic insulating layer formed on the organic semiconductor layer; And And a gate electrode formed on the organic insulating layer. 8. The organic thin film transistor according to claim 7, wherein the buffer layer is made of an organic material. A plurality of gate lines; Data lines crossing the gate lines; An organic thin film transistor connected to each of the gate lines and the data lines; And a pixel electrode connected to the organic thin film transistor, The organic thin film transistor includes: A buffer layer having hydrophobicity formed on the substrate; A hydrophilic surface treatment layer formed on a predetermined region of the buffer layer; Source / drain electrodes formed on the buffer layer; An organic semiconductor layer formed on the surface treatment layer; An organic insulating layer formed on the organic semiconductor layer; And And a gate electrode formed on the organic insulating film, And the pixel electrode is formed in contact with the drain electrode and the buffer layer. Forming a gate electrode on the substrate; Forming a buffer layer having hydrophobicity on the gate electrode; Forming a source / drain electrode on the buffer layer; Forming a surface treatment layer having hydrophilicity by surface-treating a predetermined region of the buffer layer; Forming an organic semiconductor layer on the surface treatment layer; And And forming an organic insulating layer on the organic semiconductor layer.

Images