KR101622183B1 - Method of fabricating sputtering target for oxide thin film transistor and method of fabricating active layer for oxide thin film transistor using thereof - Google Patents

Abstract

A method of manufacturing a sputtering target for an oxide thin film transistor and a method of manufacturing an active layer for an oxide thin film transistor according to the present invention is characterized in that in the manufacture of an oxide thin film transistor using an oxide semiconductor as an active layer, The present invention is characterized in that a ZTO target capable of DC (direct current) sputtering is manufactured by adding a small amount of a transparent conductive oxide (TCO) -based dopant to an oxide (ZTO) powder. As a result, oxide semiconductors having excellent characteristics can be applied to the mass production process.

Oxide thin film transistor, ZTO, TCO, dopant, DC sputtering

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of manufacturing a sputtering target for an oxide thin film transistor, and a method of manufacturing an active layer for an oxide thin film transistor. BACKGROUND ART < RTI ID = 0.0 >

The present invention relates to a method of manufacturing a sputtering target for an oxide thin film transistor, and more particularly to a method for manufacturing a sputtering target for an oxide thin film transistor used for manufacturing an oxide thin film transistor using an oxide semiconductor as an active layer, Layer. ≪ / RTI >

Recently, interest in information display has increased, and a demand for using portable information media has increased, and a light-weight flat panel display (FPD) that replaces a cathode ray tube (CRT) And research and commercialization are being carried out. Particularly, among such flat panel display devices, a liquid crystal display (LCD) is an apparatus for displaying an image using the optical anisotropy of a liquid crystal, and is excellent in resolution, color display and picture quality and is actively applied to a notebook or a desktop monitor have.

The liquid crystal display comprises a color filter substrate, an array substrate, and a liquid crystal layer formed between the color filter substrate and the array substrate.

An active matrix (AM) method, which is a driving method mainly used in the liquid crystal display, is a method of driving a liquid crystal of a pixel portion by using an amorphous silicon thin film transistor (a-Si TFT) to be.

Hereinafter, the structure of a typical liquid crystal display device will be described in detail with reference to FIG.

1 is an exploded perspective view schematically showing a general liquid crystal display device.

As shown in the figure, the liquid crystal display comprises a color filter substrate 5, an array substrate 10, and a liquid crystal layer (not shown) formed between the color filter substrate 5 and the array substrate 10 30).

The color filter substrate 5 includes a color filter C composed of a plurality of sub-color filters 7 implementing colors of red (R), green (G) and blue (B) A black matrix 6 for separating the sub-color filters 7 from each other and shielding light transmitted through the liquid crystal layer 30 and a transparent common electrode for applying a voltage to the liquid crystal layer 30 8).

The array substrate 10 includes a plurality of gate lines 16 and data lines 17 arranged vertically and horizontally to define a plurality of pixel regions P and a plurality of gate lines 16 and data lines 17 A thin film transistor T which is a switching element formed in the intersection region and a pixel electrode 18 formed on the pixel region P. [

The color filter substrate 5 and the array substrate 10 are bonded together to face each other by a sealant (not shown) formed at the periphery of the image display area to constitute a liquid crystal display panel. (Not shown) formed on the color filter substrate 5 or the array substrate 10.

Meanwhile, since the liquid crystal display device described above is a light-emitting device rather than a light emitting device and has technical limitations such as brightness, contrast ratio, and viewing angle, the liquid crystal display device is a light- Development of a new display device capable of overcoming the disadvantages has been actively developed.

OLED (Organic Light Emitting Diode), which is one of the new flat panel display devices, has excellent viewing angle and contrast ratio compared to liquid crystal displays because it is a self-luminous type. Lightweight thin type can be used because it does not need backlight And is also advantageous in terms of power consumption. In addition, it has the advantage of being able to drive a DC low voltage and has a high response speed, and is particularly advantageous in terms of manufacturing cost.

In recent years, studies have been actively made on the enlargement of an organic electroluminescent display. In order to achieve this, development of a transistor ensuring stable operation and durability by securing a constant current characteristic as a driving transistor of an organic electroluminescent device is required.

The amorphous silicon thin film transistor used in the above-described liquid crystal display device can be manufactured in a low temperature process, but has a very small mobility and does not satisfy a constant current bias condition. On the other hand, the polycrystalline silicon thin film transistor has a high mobility and a satisfactory constant current test condition, but it is difficult to obtain a uniform characteristic, so it is difficult to make a large area and a high temperature process is required.

Among them, zinc-tin-oxide (ZTO) oxide semiconductors are difficult to perform DC sputtering because of the high resistance of ZTO target, and RF (radio frequency sputtering only, which is not yet applicable to mass production.

In order to enable DC sputtering technically, the resistance of the target should be 300 m? Or less. However, since the resistance of the ZTO target exceeds this value, devices for research purposes are actively manufactured, I can not.

The present invention provides a method for manufacturing a sputtering target for an oxide thin film transistor and a method for manufacturing an active layer for an oxide thin film transistor used for manufacturing an oxide thin film transistor in which a ZTO system oxide semiconductor is used as an active layer .

It is another object of the present invention to provide a method of manufacturing a sputtering target for an oxide thin film transistor and a method of manufacturing an active layer for an oxide thin film transistor, in which a ZTO target capable of DC sputtering is manufactured.

Other objects and features of the present invention will be described in the following description of the invention and claims.

In order to achieve the above object, a method of manufacturing a sputtering target for an oxide thin film transistor according to the present invention comprises mixing zinc oxide (ZnO) based oxide semiconductor powder with a dopant powder of TCO (transparent conductive oxide) And then mixing the oxide semiconductor powder and the dopant powder after calcination, and polishing the surface after firing at a high temperature to form a ZTO target for the active layer.
The method for manufacturing an active layer for an oxide thin film transistor of the present invention may include forming an active layer made of the ZTO-based oxide semiconductor on a predetermined substrate through DC sputtering using the ZTO target .

As described above, the method of manufacturing a sputtering target for an oxide thin film transistor and the method of manufacturing an active layer for an oxide thin film transistor according to the present invention are excellent in uniformity due to the use of a ZTO-based oxide semiconductor as an active layer, Effect.

In addition, the method of manufacturing a sputtering target for an oxide thin film transistor and the method of manufacturing an active layer for an oxide thin film transistor according to the present invention can produce a ZTO target capable of DC sputtering, so that an excellent oxide semiconductor can be applied to a mass production process to provide.

Hereinafter, preferred embodiments of a method of manufacturing a sputtering target for an oxide thin film transistor and a method of manufacturing an active layer for an oxide thin film transistor according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a cross-sectional view schematically showing the structure of an oxide thin film transistor according to an embodiment of the present invention, and shows a structure of an oxide thin film transistor using a ZTO-based oxide semiconductor as an active layer.

As shown in the drawing, an oxide thin film transistor according to an embodiment of the present invention includes a gate electrode 121 formed on a substrate 110, a gate insulating film 115 formed on the gate electrode 121, a gate insulating film 115, An active layer 124 formed of a ZTO-based oxide semiconductor, and source / drain electrodes 122 and 123 electrically connected to a predetermined region of the active layer 124.

Although not shown in the figure, the gate electrode 121 is connected to a predetermined gate line, and a part of the source electrode 122 extends in one direction and is connected to a data line. The gate line and the data line are connected to a substrate 110 to define pixel regions.

The oxide thin film transistor according to the embodiment of the present invention satisfies high mobility and constant current test conditions and ensures uniform characteristics and is applicable to a large area display including a liquid crystal display and an organic electroluminescence display have.

In recent years, a great deal of attention and activity have been concentrated on transparent electronic circuits. Since the oxide thin film transistor in which the oxide semiconductor is used as an active layer has high mobility and can be manufactured at a low temperature, .

In addition, the oxide semiconductor can have a wide bandgap and can produce a UV light emitting diode (LED), a white LED and other components with high color purity, and can produce a light and flexible product by being processable at a low temperature .

The active layer 124 is formed by depositing a ZTO-based oxide semiconductor through DC sputtering. In particular, the present invention relates to a method of forming a transparent conductive oxide (TCO) Series dopant is added to fabricate a ZTO target capable of DC sputtering, which is advantageous in that an excellent oxide semiconductor can be applied to a mass production process.

The TCO-based dopant is a material that can lower the resistance of a target such as aluminum, gallium, and indium. Aluminum-zinc-oxide (AZO), gallium-zinc- oxide (GZO) Can be obtained from indium tin oxide (ITO) powder.

At this time, the dopant is doped at about 0.01 to 10 atomic percent.

Hereinafter, the principle of the sputtering technique used in the present invention and the sputtering apparatus will be described in detail with reference to the drawings.

3 is a schematic view showing the principle of the sputtering technique.

As shown in the figure, in the sputtering technique, argon ions (Ar +) 200 are excited by a plasma discharge between a target 100 made of an oxide semiconductor material to be deposited in a vacuum chamber and an anode And accelerates to a high voltage to cause the target 100 to collide with a large kinetic energy. At this time, when the kinetic energy of the argon ions 200 applied is greater than the binding energy between the atoms 300 constituting the target 100, sputtering occurs in which atoms 300 are separated from the surface of the target 100, 100 are separated from each other at the surface of the glass substrate to grow as a thin film.

4 is a cross-sectional view schematically showing a sputtering apparatus according to an embodiment of the present invention.

As shown in the figure, the sputtering apparatus according to the embodiment of the present invention includes a vacuum chamber 156 filled with argon gas, a susceptor 150 installed in the chamber 156, a target 100, A ground shield 155, and a magnet 153. As shown in FIG.

The susceptor 150 serves to fix the substrate 110 to be loaded into the vacuum chamber 156 and keep the temperature constant. The target 100 may be a thin film deposited on the substrate 110 And is fixed to a baking plate 154 to which a voltage is applied corresponding to the susceptor 150 to serve as a cathode in a plasma discharge.

The ground shield 155 is made of an electrically conductive material such as aluminum and serves as a counter electrode of the target 100 to which a negative charge is applied, To maintain a constant distance to induce a discharge.

The magnet 153 collects electrons to promote thin film deposition. The magnet 153 is provided on the target 100 to rotate and form a magnetic field when the thin film deposition process is performed.

A rod anode 152 provided between the susceptor 150 and the target 100 in the chamber 156 serves to improve the uniformity of deposition of the thin film, A mask 157 is provided to prevent the particles coming off the target 100 from depositing on the chamber 156 including the susceptor 150 during deposition.

As described above, the ZTO target used for deposition of the active layer through the sputtering apparatus is produced by adding a small amount of TCO dopant to the ZTO powder. In this case, the dopant of the TCO series may be doped with a dopant such as aluminum, gallium, As a material capable of lowering the resistance, AZO, GZO and ITO powder can be obtained, respectively. As the content of the added TCO-based dopant increases, the resistance of the target decreases.

FIG. 5 is a graph showing the results of measuring the resistance of the ZTO target according to the dopant content of the TCO series. The squares and circles show the case where GZO and AZO powder are used as dopants of the TCO series, respectively.

As shown in the figure, by adding a small amount of TCO series dopant to the ZTO powder, a resistance of 300 m? Or less capable of DC sputtering is measured, while the resistance of the target is decreased as the content of the added TCO type dopant is increased .

In this case, when the AZO powder is added to the ZTO powder by 50 wt% or more, the target resistance is measured to be 300 mΩ or less. On the other hand, when the GTO powder is added to the ZTO powder, the target resistance is 300 mΩ or less It can be seen that it is measured.

At this time, the dopant is doped at about 0.01 to 10 atomic%.

FIG. 6 is a table showing the resistance of a sputtering target for an oxide thin film transistor manufactured by mixing GTO powder with ZTO powder, and shows a result of an experiment in which resistance of a target is lowered by mixing GTO powder with ZTO powder.

As shown in the figure, when a target is prepared by mixing GZO powder with 20: 80, 30: 70, 50: 50 and 70% by weight: 30% by weight of ZTO powder, the resistance of the target is 20:80 200, 20 and 2 m ?.

When the ZTO powder was mixed with GZO powder at 20:80, 30:70, 50:50 and 70 wt%: 30 wt%, the composition ratios of zinc (Zn) and tin (Sn) were 4.2: 1 and 5.0: , 6.6: 1 and 8.0: 1.

When the GZO powder is added to the ZTO powder, the resistance of the target can be reduced. In particular, DC sputtering can be performed when the GZO is 30 wt% or more. At this time, the doping amount of gallium (Ga) %.

FIG. 7 is a table showing the resistance of a sputtering target for an oxide thin film transistor manufactured by mixing AZO powder with ZTO powder, and shows an experiment in which AZO powder is mixed with ZTO powder to lower the resistance of the target.

As shown in the figure, when AZO powder was mixed with ZTO powder at 20:80, 30:70, 50:50 and 70 wt%: 30 wt%, the resistance of the target was 70:30 1.5, 1.2, and 300 m?.

When the AZO powder was mixed with the ZTO powder at 20:80, 30:70, 50:50 and 70 wt%: 30 wt%, the composition ratios of zinc (Zn) and tin (Sn) were 4.2: 1 and 5.0: , 6.6: 1 and 8.0: 1.

When the AZO powder is added to the ZTO powder, the resistance of the target can be reduced. In particular, it can be seen that DC sputtering is possible when AZO is 50 wt% or more.

Hereinafter, a method of manufacturing a sputtering target for an oxide thin film transistor according to an embodiment of the present invention will be described in detail with reference to the drawings.

8 is a flowchart showing a method of manufacturing a sputtering target for an oxide thin film transistor according to an embodiment of the present invention.

For making the ZTO target, powders of AZO, GZO and ITO of TCO series are mixed with a ZTO powder by a ball mill so as to have a stoichiometric composition (S110).

At this time, the powders such as AZO, GZO and ITO are kept at a level to be added in a small amount in the form of a doped material, and a material capable of lowering resistance of the target such as Al, Ga and In is doped, Is in the range of 0.01 to 10 atomic%.

For reference, the ball mill refers to a crusher for crushing or crushing solid particles or for discharging flour.

Thereafter, calcination is performed in a nitrogen / oxygen mixed gas flow, and then ball milling is performed on the obtained pulverulent body (S120, S130). In this case, the powder means an object in which solid particles are concentrated, and the calcining process refers to an operation of heating a material to a high temperature to remove a part or all of the volatile components.

Then, uniaxial pressing is performed, and the ZTO target is formed through surface polishing after firing at a high temperature (S140, S150). At this time, the firing process refers to an operation for making a curable material by heating the combined raw materials.

In the present invention, it is possible to retain the conductivity of the target by adding a small amount of TCO-based dopant to the ZTO powder. Thus, by producing a ZTO target capable of DC sputtering, excellent oxide semiconductors can be produced in a mass production process .

In particular, the DC sputtering is advantageous in that the deposition rate is faster and the sputtering efficiency is better than that of RF sputtering, and the DC sputtering apparatus is advantageous in that it is inexpensive, easy to control, and consumes less power.

While a great many are described in the foregoing description, it should be construed as an example of preferred embodiments rather than limiting the scope of the invention. Therefore, the invention should not be construed as limited to the embodiments described, but should be determined by equivalents to the appended claims and the claims.

1 is an exploded perspective view schematically showing a general liquid crystal display device.

2 is a cross-sectional view schematically showing the structure of an oxide thin film transistor according to an embodiment of the present invention.

3 is a schematic view showing the principle of a sputtering technique;

4 is a cross-sectional view schematically showing a sputtering apparatus according to an embodiment of the present invention.

5 is a graph showing the results of measuring the resistance of the ZTO target according to the dopant content of the TCO series.

6 is a table showing resistance of a sputtering target for an oxide thin film transistor produced by mixing GZO powder with ZTO powder.

7 is a table showing resistance of a sputtering target for an oxide thin film transistor produced by mixing AZO powder with ZTO powder.

8 is a flowchart showing a method of manufacturing a sputtering target for an oxide thin film transistor according to an embodiment of the present invention.

DESCRIPTION OF REFERENCE NUMERALS

110: substrate 115: gate insulating film

121: gate electrode 122: source electrode

123: drain electrode 124: active layer

151: Target

Claims (9)

Mixing zinc oxide (ZnO) based oxide semiconductor powder with a dopant powder of TCO (transparent conductive oxide) type; Mixing and calcining the mixed oxide semiconductor powder and the dopant powder; And And polishing the surface after firing at a high temperature to form a ZTO target for the active layer. The method of claim 1, wherein the dopant powder is selected from the group consisting of AZO (Aluminum Zinc Oxide), GZO (Gallium Zinc Oxide), and ITO (Indium Tin Oxide) powders. [3] The method of claim 2, wherein the AZO, GZO, and ITO powders are doped with 0.01 ~ 10 atomic% of Al, Ga, and In, which can lower the resistance of the target, respectively. The method of manufacturing a sputtering target for an oxide thin film transistor according to claim 1, wherein the mixing is performed using a ball mill. The method of manufacturing a sputtering target for an oxide thin film transistor according to claim 1, wherein the sputtering target is calcined in a mixed gas flow of nitrogen / oxygen. The method of manufacturing a sputtering target for an oxide thin film transistor according to claim 1, wherein the sputtering target is fired at a high temperature by uniaxial pressing. 3. The method of claim 2, wherein the GZO powder is added in an amount of 30 wt% or more, wherein a doping amount of gallium is 0.1 atomic%. 3. The method of manufacturing a sputtering target for an oxide thin film transistor according to claim 2, wherein the AZO powder is added in an amount of 50 wt% or more. Mixing a TCO-based dopant powder with a ZTO-based oxide semiconductor powder; Mixing and calcining the mixed oxide semiconductor powder and the dopant powder; Polishing the surface after firing at a high temperature to form a ZTO target; And And forming an active layer made of the ZTO-based oxide semiconductor on a predetermined substrate through DC sputtering using the ZTO target.

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