KR101669723B1 - Ge DOPING InZnO ACTIVE-LAYER APPLICATED THIN FILM TRANSISTOR AND MANUFACTURING METHOD THEREOF - Google Patents

Abstract

In the oxide thin film transistor of the present invention, a substrate; A gate electrode formed on the substrate; An insulator layer formed on the gate electrode; An active layer including a first active layer thin film and a second active layer thin film formed on the insulator layer and having a laminated structure; And a source electrode and a drain electrode connected to the active layer, wherein the first active layer thin film comprises InZnO and the second active layer thin film comprises germanium-doped InZnO.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a thin film transistor using an InZnO active layer doped with germanium and a method of manufacturing the same.

The present invention relates to a thin film transistor including an active layer composed of two layers of a laminate structure and a method of manufacturing the same, and more particularly, to a thin film transistor including a layered structure of InZnO (indium- zinc-oxide) layer and germanium-doped InZnO layer A thin film transistor including an active layer, and a method of manufacturing the same.

As the display industry develops, thin film transistor (TFT) technology, which is indispensable for displays, is also developing. Thin film transistors are mainly used in flat panel displays such as liquid crystal displays, organic light emitting diode displays and the like. As displays have become larger in size and higher in resolution, attention has been focused on oxide TFTs having higher uniformity and electron mobility than conventional a-Si TFTs, poly-crystal silicones, and the like. An InZnO layer is mainly used as an active layer of such an oxide TFT.

InZnO is an indium-zinc-oxide material most widely used as a semiconductor active layer thin film, and has an advantage of being excellent in electron mobility and being transparent. However, since InZnO is not easy to control the carrier concentration, a high off current is a problem, and when a voltage is applied to the device for a long time, a threshold voltage for switching the device changes, thereby decreasing the reliability of the device. In order to overcome this disadvantage, InGaZnO has been discovered. Ga is a rare earth metal, which has a low storage capacity and is expensive. Therefore, it is necessary to substitute Ga at low cost with the effect of Ga.

An existing thin film transistor and its manufacturing method are disclosed in Korean Patent No. 10-1354883 (published on September 12, 2012).

SUMMARY OF THE INVENTION It is an object of the present invention to provide a thin film transistor capable of controlling carrier concentration with high electron mobility by fabricating a thin film transistor including an active layer having a laminated structure of germanium-doped InZnO layer and InZnO layer .

SUMMARY OF THE INVENTION It is an object of the present invention to provide a thin film transistor capable of controlling carrier concentration with high electron mobility by fabricating a thin film transistor including an active layer having a laminated structure of germanium-doped InZnO layer and InZnO layer .

Solution to the Problem

According to an aspect of the present invention, there is provided an oxide thin film transistor comprising: a substrate; A gate electrode; An insulator layer; An active layer, and a source electrode and a drain electrode.

The gate electrode is formed on the substrate.

The insulator layer is formed on the gate electrode.

The active layer includes a second active layer thin film formed on the insulator layer.

In one embodiment, the second active layer thin film may include germanium and the InZnO. For example, the second active layer may comprise a germanium-doped InZnO layer.

In one embodiment, the active layer may further include a first active layer thin film having a laminated structure with the second active layer thin film below the second active layer thin film and including InZnO. In still another embodiment, the active layer may further include a first active layer thin film having a laminated structure with the second active layer thin film on the second active layer thin film and including InZnO. In an embodiment, the laminated structure may be a structure in which the second active layer thin film is formed on the first active layer thin film. In another embodiment, the laminated structure may be formed on the second active layer thin film, 1 active layer may be formed. That is, the stacking order of the first active layer thin film and the second active layer thin film in the laminated structure is not limited.

The source electrode and the drain electrode may be connected to the active layer.

According to another embodiment of the present invention, a method of fabricating an oxide thin film transistor in which an active layer including a first active layer thin film and a second active layer thin film is formed on an insulator layer includes the steps of: preparing; A first sputtering step; And a second sputtering step.

In the preparation step, a gate electrode substrate having a germanium-containing target, an InZnO target, and an insulator layer on which the first active layer thin film and the second active layer thin film are deposited is prepared in one chamber portion.

The chamber portion may internally accommodate the germanium-containing target, the InZnO target, and the gate electrode substrate on which the insulator layer is formed, and may include therein a space in which the first sputtering step and the second sputtering step can be performed have.

The germanium-containing target is a material for doping germanium to InZnO in the second active layer thin film.

In one embodiment, the germanium-containing target may be a GeO ₂ target.

The InZnO target is a material for forming InZnO in the first active layer thin film and the second active layer thin film.

The target material may be a material containing the first active layer thin film and the second active layer thin film, and may include a substrate, a gate electrode, and an insulator layer.

The first sputtering is a step of applying electric power to the InZnO target to form the first active layer thin film including InZnO.

The second sputtering is a step of simultaneously applying power to the target including germanium and the InZnO target to form the second active layer thin film including germanium-doped InZnO. The second sputtering step is a co-sputtering step.

In one embodiment, the second sputtering step may be performed after the first sputtering step. For example, the first active layer thin film is formed on the gate electrode substrate on which the insulator layer is formed through the first sputtering step, and the second active layer thin film is formed on the first active layer thin film through the second sputtering step .

In one embodiment, the first sputtering step may be performed after the second sputtering step. For example, the second active layer thin film is formed on the gate electrode substrate on which the insulator layer is formed through the second sputtering step, and the first active layer thin film is formed on the second active layer thin film through the first sputtering step .

In one embodiment, the power applied to the germanium-containing target may be greater than 0 W and less than or equal to 10W.

In one embodiment, the power applied to the GeO ₂ target may be less than 1/5 of the power applied to the InZnO target.

In one embodiment, the oxygen partial pressure in the chamber portion may be between 2 and 4%.

The present invention as described above has an effect of having high uniformity and electron mobility as compared with the InZnO layer used as an active layer of a thin film transistor.

In addition, since germanium is used instead of the Ga of the conventional InGaZnO, the manufacturing cost of the thin film transistor is lowered, thereby enabling mass production of the thin film transistor.

Finally, the use of an active layer made of a laminated structure of InZnO layer and germanium-doped InZnO layer has higher electron mobility and higher Ion / Ioff ratio than conventional InZnO active layer, thereby improving the performance of the thin film transistor .

FIGS. 1A and 1B are views showing a structure of a thin film transistor according to an embodiment of the present invention.
FIG. 2 is a graph showing conductivity, carrier concentration, and Hall mobility of a germanium-doped InZnO layer according to electric power applied to a germanium-containing target.
3 is an XRD analysis graph of germanium-doped InZnO according to the power applied to the germanium-containing target.
FIG. 4 is a graph showing output characteristics when a gate voltage is applied to a thin film transistor to which an active layer having a stacked structure of a first active layer thin film and a second active layer thin film is applied and a thin film transistor not used.
5 is a graph showing the transmittance of germanium-doped InZnO thin film in the visible light region.
FIG. 6A is an XPS analysis graph of the existing active layer of the present invention, and FIG. 6B is an XPS analysis graph of the active layer of the present invention.
7 is a graph of output characteristics of the active layer and the conventional active layer of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and similarities. It is to be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but on the contrary, is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the term "comprises" or "having" is intended to designate the presence of stated features, elements, etc., and not one or more other features, It does not mean that there is none.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

FIGS. 1A and 1B are views showing a structure of a thin film transistor according to an embodiment of the present invention.

1A and 1B, an oxide thin film transistor of the present invention includes a substrate; A gate electrode (2) formed on the substrate (1); An SiO 2 insulator 3 formed on the gate electrode 2; Active layers 4 and 5 formed on the SiO 2 insulator 3 and a source electrode 6 and a gate electrode 7 connected to the active layer.

The active layer includes a first active layer thin film 4 containing InZnO and a second active layer thin film 5 containing germanium-doped InZnO. The first active layer thin film 4 and the second active layer thin film 5 are stacked Structure. In this case, the active layer may have a laminated structure in which the second active layer thin film 5 is formed on the first active layer thin film 4 as shown in FIG. 1 (a), and the second active layer thin film 5 5) having the first active layer thin film 4 formed thereon.

The oxide thin film transistor was fabricated through the following steps.

≪ Example 1 >

First, Arsenic was doped into silicon that can be used as a gate electrode layer, and a silicon wafer was deposited on the substrate. TCE (Trichlorethylene), acetone, methanol, and deionized water (DI) were washed simultaneously with ultrasonic waves to clean the surface of the silicon wafer every 10 minutes to remove contamination on the surface of the silicon wafer. SiO ₂ was deposited as an insulator layer to a thickness of 200 nm on the silicon wafer. Then the insulator in order to produce the part for applying a gate voltage putting covers the etch mask, the remaining portion other than the pattern for the contact and the gate voltage of the insulating layer, SiO ₂ etching, one of the BOE (Buffered Oxide Etchant) of the Layer was deposited and the SiO ₂ of the pattern portion not covered with the etch mask was etched to form a pattern for contact with the gate voltage.

A GeO ₂ target, an InZnO target and a silicon wafer on which the insulator layer was deposited were prepared as a germanium-containing target in one chamber. Then, to form an InZnO film as a first active layer thin film at room temperature, the first active layer thin film was deposited on the insulator layer by a first sputtering process using only an InZnO target. At this time, argon (Ar) and oxygen (O ₂ ) gas were mixed in the chamber, and the process pressure of the gas in the chamber was maintained at 2 × 10 ^-3 torr. In the first sputtering process, the power applied to the InZnO target was kept constant at 50W. Also, in the first sputtering process, the power applied to the GeO ₂ target was set to 0 W, and the process proceeded. The first sputtering process was performed while varying the oxygen partial pressure [O ₂ / (O ₂ + Ar)] of the gas in the chamber to 0, 2, and 4%. Thereafter, the first active layer thin film was heat-treated using a furnace.

A source electrode and a drain electrode were deposited on the active layer including the first active layer thin film using an electron beam evaporator. In this case, the source and drain electrodes are aluminum, and the source and drain electrodes have a thickness of 100 nm.

Through the above process, an oxide thin film transistor using an InZnO layer as an active layer was manufactured.

≪ Example 2 >

The remaining process conditions except for the sputtering process are the same as the process conditions of the first embodiment, and repetitive description will be omitted. The thin film transistor of Embodiment 2 is described only for the sputtering process for manufacturing the active layer, which is different from the thin film transistor of Embodiment 1 and the active layer.

In order to manufacture the thin film transistor of Example 2, a GeO ₂ target, an InZnO target and a silicon wafer on which the insulator layer was deposited were prepared as a germanium-containing target in one chamber. A second sputtering process using the InZnO target and the GeO ₂ target in order in the post room temperature to produce the second of Ge is doped as the active layer thin film InZnO film in the InZnO target and the co-sputtering method of applying the electric power at the same time in the GeO ₂ target And the second active layer thin film was deposited on the insulator layer. At this time, argon (Ar) and oxygen (O ₂ ) gas were mixed in the chamber, and the process pressure of the gas in the chamber was maintained at 2 × 10 ^-3 torr. In the second sputtering process, the power applied to the InZnO target was kept constant at 50 W and the power applied to the GeO ₂ target was changed to 5, 10, 15, 20, 25, and 30 W, . The second sputtering process was performed while changing the oxygen partial pressure [O ₂ / (O ₂ + Ar)] of the gas in the chamber to 0, 2, and 4%. The second active layer thin film thus formed was heat-treated using a furnace.

An oxide thin film transistor using an InZnO layer doped with germanium as an active layer was fabricated through the above process.

≪ Example 3 >

The remaining process conditions except for the sputtering process are the same as the process conditions of the first embodiment, and repetitive description will be omitted. The thin film transistor of Embodiment 3 is described only for the sputtering process for manufacturing the active layer, which is different from the thin film transistor of Embodiment 1 only in the active layer.

In order to manufacture the thin film transistor of Example 3, a GeO ₂ target, an InZnO target and a silicon wafer on which the insulator layer was deposited were prepared as a target containing germanium in one chamber. Thereafter, a first sputtering process was performed using an InZnO target and a GeO ₂ target in order to produce the first active layer thin film and the second active layer thin film at room temperature, and then a second sputtering process was performed. First, the first active layer thin film is deposited on the insulator through the first sputtering process. Thereafter, the second active layer thin film is deposited on the first active layer thin film through the second sputtering process. At this time, argon (Ar) and oxygen (O ₂ ) gas were mixed in the chamber, and the process pressure of the gas in the chamber was maintained at 2 × 10 ^-3 torr. In the first sputtering process, the power applied to the InZnO target was kept constant at 50 W, the power applied to the InZnO target was kept constant at 50 W in the second sputtering process, and the power applied to the GeO ₂ target was set at 10 W The sputtering process was carried out. The first sputtering process and the second sputtering process were performed while changing the oxygen partial pressure of the gas in the chamber [O ₂ / (O ₂ + Ar)] to 2%. Thereafter, the first active layer thin film and the second active layer thin film were heat-treated using a furnace.

Through the above process, an oxide thin film transistor having an InZnO layer doped with a germanium-doped InZnO layer as a active layer was fabricated on the InZnO layer and the InZnO layer.

<Example 4>

The remaining process conditions except for the sputtering process are the same as the process conditions of the first embodiment, and repetitive description will be omitted. The thin film transistor of Embodiment 3 is described only for the sputtering process for manufacturing the active layer, which is different from the thin film transistor of Embodiment 1 only in the active layer.

In addition, the thin film transistor of Example 4 is the same as the thin film transistor of Example 3 except that the second sputtering process is performed and then the first sputtering process is performed. Therefore, the thin film transistor of Example 4 was manufactured by depositing the second active layer thin film on the insulator and depositing the first active layer thin film on the second active layer thin film.

Through the above process, an oxide thin film transistor having an InZnO layer doped with germanium and an InZnO layer having a stacked structure above the germanium doped InZnO layer was manufactured.

<Example 2 Characteristic Analysis of Thin Film Transistor>

First, the electrical characteristics of the thin film transistor according to the variation of the process conditions of the second embodiment are analyzed.

FIG. 2 is a graph showing the conductivity, carrier concentration, and Hall mobility of the thin film transistor of Example 2 according to power applied to the germanium-containing target.

3 is a graph showing the XRD results according to the power applied to the GeO2 target of the second embodiment.

Referring to FIG. 2, the conductivity, carrier concentration, and hole mobility in the case where electric power of more than 0 W but less than 10 W is applied to the GeO 2 target of Example 2 are the conductivity when no electric power is applied to the GeO 2 target of Example 1, Concentration and hole mobility were higher. This is because when a voltage of more than 0 W and less than 10 W is applied to the GeO 2 target of Embodiment 2, a small amount of germanium ions are doped in the InZnO layer, thereby generating additional electrons, thereby increasing the carrier concentration as compared with the thin film transistor of Embodiment 1 I will. The increase in the conductivity and the hole mobility is caused by the increase in the carrier concentration. As the carrier concentration increases, the number of carriers in the thin film transistor increases and the hole mobility increases. When the hole mobility increases, It becomes active and the conductivity becomes high.

However, when the electric power applied to the GeO2 target of Example 2 was more than 10 W, it was confirmed that the conductivity, the carrier concentration and the hole mobility were continuously decreased. In particular, the carrier concentration when the power of 15 W was applied to the GeO 2 target of Example 2 was higher than that of Example 1, but it was confirmed that the conductivity and the hole mobility were rather lower than those of Example 1. The reason for this is that if the composition of germanium doped in InZnO is out of a certain level, the germanium ion bonds with the oxygen of the InZnO layer to decrease the carrier concentration. Referring to FIG. 3, it can be seen that the In2O3 (321) peak gradually increases as the power increases from 0 to 30 W for the GeO2 target. In the graph of FIG. 3, the (a), (b), (c) and (d) picture lines represent the picture lines when 0W, 10W, 20W and 30W power is applied to the GeO2 target, respectively. This means that the In2O3 component is increased, which is interpreted as a phenomenon that occurs when the germanium ions are doped beyond a certain level to weaken the bonding of the InZnO layer and to separate the crystallized In2O3. Therefore, it can be confirmed that the conductivity, the carrier concentration, and the hole mobility are the highest when the electric power applied to the GeO2 target is 10W.

Table 1 shows the threshold voltage (Vth), the saturation mobility ( _sat ), the saturation mobility ( _sat ) of the thin film transistor including the active layer fabricated in accordance with the change of the oxygen partial pressure of the gas in the chamber portion when the power applied to the germanium- _on / _off ratio and Subthreshole Swing (SS).

GeO2 applied power (W)
Oxygen partial pressure
(%) Threshold voltage
(V) u _sell
(cm ² / Vs)
I _on / I _off ratio SS (Subthreshole Swing)
(V / dec)
10
4 -7.2
21.97 1 X 10 ⁷
1.42
10
2 0
13.05 3 X 10 ⁷
0.95

Referring to Table 1, there is a problem that the threshold voltage value when the oxygen partial pressure is 4% is 7.2 V and the threshold voltage value is negative, so that the semiconductor device can not be used as a semiconductor device. On the other hand, when the oxygen partial pressure is 2%, the threshold voltage is 0V, which is not a negative value, and thus the semiconductor device can be applied. In addition, the saturation mobility value of the thin film transistor at the oxygen partial pressure of 2% was lower than that of the thin film transistor at the oxygen partial pressure of 4%, but the I _on / I _off ratio, which is another electrical characteristic, The SS value was also found to be as low as 2/3. Therefore, it was confirmed that the electrical characteristics were improved compared with the case of the thin film transistor having the oxygen partial pressure of 2% and the oxygen partial pressure of the thin film transistor of 4%.

4 is a graph showing the electrical characteristics according to the concentration of germanium when the thin film transistor of Example 2 is manufactured under the condition of 2% oxygen partial pressure.

Referring to FIG. 4, the power applied to the GeO2 target of the second embodiment has a negative value when a power less than 0 to 10 W is applied to the GeO2 target, but when a power of 10 to 20 W is applied, Vth ) Is increased to have a value of 0 or more. However, when the power applied to the GeO2 target exceeds 20 W, it can be confirmed that the germanium causes a structural disorder in the active layer and the Vth decreases again. Therefore, it is confirmed that Vth has the best characteristics when power of 10 to 20 W is applied. In the case of SS, when the power exceeding 0 but less than 10W is applied to the GeO2 target, the power decreases sharply. When the power of 10 to 20W is applied, the value is maintained to be similar but rapidly increases when the power of 20W is applied I could confirm. Therefore, it is confirmed that SS value has the best characteristics when power of 10 to 20 W is applied. In the case of saturation mobility, when the power of 0 to 5 W is applied to the GeO 2 target, the power is higher than when the power is not applied to the GeO 2 target. It is confirmed that the thin film transistor according to the present invention exhibits the best performance even when the power of 10 W is applied to the GeO2 target, although the saturation mobility is slightly lowered, but the other electrical characteristics are greatly improved. The results are shown in Table 1.

It was confirmed that the thin film transistor of Example 2 was the best when the power of 10 W was applied to the GeO2 target and the active layer was fabricated at an oxygen partial pressure of 2%.

5 is a graph showing the transmission spectrum of the thin film transistor of Example 2. FIG.

Referring to FIG. 5, the thin film transistor of Example 2 was fabricated on a GeO 2 target with an applied power of 10 W and an oxygen partial pressure of 2%. In the graph of FIG. 4, it can be seen that the transmittance of the thin film transistor of Example 2 is 80 to 90% at a visible light frequency range of 380 nm to 800 nm. Thus, it can be confirmed that the thin film transistor of the second embodiment can be applied to a transparent device.

<Example 1 and Example 2 Comparative Analysis of Electrical Characteristics of Thin Film Transistors>

Next, electrical characteristics of the thin film transistors of Example 1 and Example 2 were compared and analyzed.

6A and 6B are XPS analysis graphs of the thin film transistor of Example 1 and the thin film transistor of Example 2, respectively.

Referring to FIGS. 6A and 6B, in the two graphs, the O1 pick is a pick associated with the degree of bonding between oxygen ions and metal atoms in the active layer of the thin film transistor, and the O2 pick is a pick associated with the oxygen deficiency region in the active layer. The higher the area ratio of the oxygen-deficient region in total oxygen, the more the carrier concentration and conductivity are increased. First, referring to the graph related to the first embodiment of FIG. 6A, the O1 peak can be observed at 530.24 eV, and the O2 peak can be observed at 513.74 eV. Referring to the graph relating to Example 2 of FIG. 6B, the O1 pick was observable at 530.24 eV, and the O2 pick was observable at 531.70 eV. From the results, it was found that the area of the oxygen-deficient area was divided by the area of the total oxygen area and converted into the% value. As a result, it was measured to be 43.24% in Example 1 and 44.67% in Example 2. As a result, The area ratio of the oxygen-deficient region was high.

7 is a graph comparing output characteristics when gate voltages are applied to the thin film transistors of the first and second embodiments. 7 shows the output characteristics when the gate voltage is applied to the thin film transistor of the first embodiment, and the graph shown by the squares shows the output characteristics when the gate voltage is applied to the thin film transistor of the second embodiment.

7, when the same gate voltage (5V or 10V) and the same drain voltage (Vd) are applied to the thin film transistors of Embodiment 1 and Embodiment 2, the drain current Id of Embodiment 2 is the same as Embodiment 1 Which is higher than the drain current of the transistor. Particularly, when the gate voltage Vg is 10 V, it is confirmed that the drain current value of the second embodiment is about 1.5 to 2 times higher than the drain current value of the first embodiment. Therefore, it was confirmed that the thin film transistor of Example 2 showed higher output efficiency than the thin film transistor of Example 1. [ These results are the same as those of FIGS. 6A and 6B, and it is confirmed that the performance of the thin film transistor of the second embodiment is superior to that of the thin film transistor of the first embodiment. It is also confirmed that these results are the same as those of FIG.

&Lt; Comparative Example of Electrical Characteristics of Thin Film Transistor of Example 3 or Example 4 and Example 2 >

Table 2 shows the saturation mobility ( _sat ), I _on / I _off ( _t ) of the thin film transistor of Example 3 or Example 4 and the thin film transistor of Example 2 in which the active layer made of the laminated structure of the first active layer thin film and the second active layer thin film was applied. Ratio and SS (Subthreshole Swing). The characteristics of Example 3 and Example 4 were measured in the same manner. Hereinafter, the thin film transistor of Example 3 and the thin film transistor of Example 2 were compared and analyzed.

The active layer including the first active layer thin film and the second active layer thin film μ _sat
(cm ² / Vs)
I _on / I _off ratio SS (Subthreshole Swing)
(V / dec)
apply
33.50 2 X 10 ⁷

1.83
Unapplied
13.05 1 X 10 ⁷
0.98

Referring to Table 2, the saturation mobility and I _on / I _off ratio of the thin film transistor of Example 3 were 33.50 cm ² / Vs and 2 × 10 ⁷ , respectively, and the saturated mobility of the thin film transistor of Example 2 and I _{the on} / _off ratio of 13.05 cm ² / Vs and 1 × 10 ⁷ . Although the SS value of the thin film transistor of Example 3 was 1.83 V / dec, which was higher than the SS value of 0.98 V / dec of the thin film transistor of Example 2, it was confirmed that the saturation mobility and the I _on / I _off ratio were high.

Therefore, it can be confirmed from the above table that the thin film transistor of Example 1 has a higher performance than the thin film transistor of Example 2.

Claims (10)

Board;
A gate electrode formed on the substrate;
An insulator layer formed on the gate electrode;
An active layer formed on the insulator layer and including a second active layer thin film; And
And a source electrode and a drain electrode connected to the active layer,
Wherein the second active layer thin film comprises germanium-doped InZnO,
And a first active layer thin film including InZnO having a laminated structure with the second active layer thin film above or below the second active layer thin film,
Oxide thin film transistor. delete delete A method of manufacturing an oxide thin film transistor in which an active layer including a first active layer thin film and a second active layer thin film is formed on an insulator layer,
Preparing a gate electrode substrate having a germanium-containing target, an InZnO target, and an insulator layer on which the first active layer thin film and the second active layer thin film are deposited, in one chamber portion;
A first sputtering step of applying electric power to the InZnO target to form the first active layer thin film including InZnO;
A second sputtering step of simultaneously applying power to the target including germanium and the InZnO target to form the second active layer film including germanium-doped InZnO before or after the first sputtering step;
Wherein the oxide thin film transistor is formed on the substrate. delete delete 5. The method of claim 4,
Wherein the germanium-containing target is a GeO ₂ target,
Oxide thin film transistor. 5. The method of claim 4,
Wherein the power applied to the germanium-containing target is greater than 0 W but less than or equal to 10 W,
Oxide thin film transistor. 5. The method of claim 4,
Wherein the oxygen partial pressure in the chamber portion is 2 to 4%
Oxide thin film transistor. 5. The method of claim 4,
Wherein the power applied to the germanium-containing target has a magnitude of 1/5 or less of a power applied to the InZnO target.
Oxide thin film transistor.

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