KR100399763B1 - Method for manufacturing ZnO layer using sputtering deposition - Google Patents

Abstract

The present invention provides a method for forming a ZnO film by using a sputtering apparatus for generating a plasma having a ZnO target in a vacuum chamber and a sapphire substrate arranged to face the ZnO target and facing away from the ZnO target. Providing a ZnO target to expose to use gas in the sputtering apparatus; Supplying at least one reactive gas to the sputtering device; Supplying power to the sputtering apparatus to form a plasma; Depositing a ZnO film at a thickness of 1 to 200 Å on a sapphire substrate at a temperature of 25 to 350 ° C. by the action of the plasma; And increasing the temperature of the substrate to 400 to 700 ° C. after the deposition step, and then depositing a ZnO film on the primary ZnO film to a thickness of 1 μm to 5 μm.

Description

Method for manufacturing zinc oxide film using sputtering deposition {Method for manufacturing ZnO layer using sputtering deposition}

The present invention relates to a method for forming a thin film on a substrate, and more particularly, to a method for sputter deposition of a ZnO film on a substrate.

One conventional method for obtaining a high quality zinc oxide (ZnO) film has been a method of using a buffer layer (buffer film) such as MgO between a ZnO film and a substrate (Ref .: Y. Chen, HJ Ko, SK Hong, and T. Yao, Appl. Phys. Lett. 76,559 (2000)] However, this method adds a heterogeneous substance called MgO, which complicates the manufacturing process and results in a molecular beam epitaxy. Because of the method, mass production or industrial applications were not possible.

Other methods for obtaining high quality ZnO films have used a two step process [Ref. S. H. Park, B. C. Seo, and G. W. Yoon, J. Vac. Sci. Technol. A 18 (5), Sep / Oct 2000]. This method first deposits a polycrystalline buffer layer (complete layer) of about 1000 mW in the first step. Next, a polycrystalline film is deposited. However, since this method uses a polycrystalline film in both the primary and secondary processes, there are limitations in producing a high quality ZnO film, such as impurity phases on the (101) plane in addition to the (002) plane. have.

The present invention has been made to solve the above problems, and an object thereof is to provide a method for forming a high quality epitaxy film using a sputtering method.

1 is a schematic view showing an example of a sputtering deposition apparatus used to perform a thin film forming method according to the present invention.

2 is a graph showing the semi-full width of the seta rocking of the thin film deposited according to Comparative Example 1, 2 and the embodiment of the present invention.

Figure 3 is a graph showing the X-ray diffraction measurement results of the thin film deposited according to Comparative Examples 1 and 2 and the embodiment of the present invention.

4A to 4C are graphs showing surface roughnesses of the thin films deposited according to Comparative Examples 1 and 2 and the embodiment of the present invention, and FIG. 4A is a deposition example 1 and FIG. 4C is a graph showing the case of deposition in Comparative Example 2.

In order to achieve the above object, the present invention includes two steps including a low temperature deposition step of depositing only a two-dimensional layer and a high temperature deposition step of depositing the remaining film by raising the temperature of the substrate rather than the deposition temperature of the low temperature deposition step. The deposition method was used. Generally, the higher the temperature of the substrate during ZnO deposition, the better the film quality (reduction of full width at half maximum), but since it has a 3D circumferential or island growth mode rather than a 2D layer growth mode from the beginning of deposition. , The roughness of the deposited film is increased. See, Y. Chen, HJHong and T. Yao, Applied Physics Letters Vol. 76, 559 Page (2000), A. Ohtomo, H. Kimura, T. Mkkino, Y. Segawa, H.Koinuma and M.Kawasaki, J.Crystal Growth, 214/215 (2000) 284-288] On the other hand, if the temperature of the substrate is low, the 2D layer is grown at the beginning of deposition and then switched to 3D circumferential or island growth mode Although the roughness of the film decreases, the film quality has a reduced characteristic (increase in half width) compared to high temperature deposition. Reference [SIPa, TSCho, SJDoh, JLLee and JHJe, Applied Physics Letters, Vol. 77, 349 (2000)] Thus, ultimately, the improved film quality (ie, low semi-full width), which is a benefit of each temperature, Need to provide a film having a roughness at the same time.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a ZnO film having a low semi-full width and low roughness using a sputtering deposition method.

The present invention is characterized in that the film deposited in the low temperature deposition step has only 2D layer components, and the high temperature deposition step is carried out at a higher temperature than the low temperature deposition step.

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

First, Comparative Examples 1 and 2 are shown.

Comparative Example 1

The deposition is carried out by the sputtering method under the following conditions.

Carry out one-step deposition.

Basic Pressure: 10 ^-6 Torr

Gas used: Ar (99.99%), oxygen (99.999%)

Process pressure: 2 x 10 ^-2 Torr

Power: 20 W

Substrate: Sapphire (Al ₂ O ₃ ) (002)

Target: ZnO

Substrate temperature: 300 ℃

As a result of performing theta rocking in the X-ray diffraction method measured on the thin film deposited in the comparative example, as shown in FIG. 2, it showed a three-dimensional growth mode. As a result of measuring the half-width width, it turns out that it is 0.72 degrees. Here, the smaller the half-width width of theta locking means, the greater the epitaxy and the better the film quality. The roughness of the substrate was 30 kPa.

Comparative Example 2

Sputtering deposition was performed under the following conditions.

One step deposition process was performed.

Basic Pressure: 10 ^-6 Torr

Gas used: Ar (99.99%), oxygen (99.999%)

Process pressure: 2 × 10 ^-6 Torr

Power: 20 W

Substrate: Sapphire (Al ₂ 0 ₃ ) (002)

Target: ZnO

Substrate temperature: 500 ℃

Powder scanning (Θ-2Θ scanning) was performed by X-ray diffraction on the thin film deposited in Comparative Example 2, and as a result, it was a polycrystalline film having both (002) and (101) phases as shown in FIG. . The presence of two or more phases simultaneously means that the epitaxy of the thin film is significantly reduced. The surface roughness of the substrate is about 3000Å and it can be seen that it has a very rough surface structure.

Example 1

This embodiment presents a method of depositing a ZnO film using a sputtering method.

Embodiment 1 of the present invention will be described with reference to Fig. 1. However, the same reference numerals are given to the same or corresponding parts as in the prior art.

In the apparatus for carrying out the sputtering method using the two deposition steps of the present invention, as shown in FIG. 1, a cathode 3 is installed in the vacuum chamber 1, and a ZnO target 2 is disposed below the cathode 3. ) Is attached. The target 2 is provided with a plasma power source 6 for applying a DC bias. An anode 4 facing the same axis in parallel with the target 2 is provided, and a sapphire (Al ₂ O ₃ ) substrate 5 is positioned above the anode 4. In addition, a plasma power source 6 is installed to generate a plasma by using a gas such as oxygen and alcon inside the vacuum chamber 1, and a vacuum system 7 for generating a vacuum inside the vacuum chamber 1. This is installed. When sputtering deposition is performed using such a device, the plasma gas ionized by + generated by the plasma power source 6 collides with the target 2 to which a negative bias voltage is applied, and the material of the target 2 is sputtered. Let's do it. Thus, particles falling off the target 2 fly toward the substrate 5 and are deposited on the substrate 5.

The sputtering method of the present invention will be described.

First, inert gas and oxygen (99.999%) of Ar (99.99%) are introduced into the vacuum chamber 7 through the introduction pipe 8, and the gas pressure in the vacuum chamber 7 is set to 10 ^-6 Torr. . About 20W of electric power is supplied to the ZnO target 2 from the plasma power source 6, the Ar ions in plasma collide with the target 2, sputter particles are formed from the surface of the target 2, and sputter particles Is deposited on the (002) plane of the substrate 5 at about 300 ° C. for about 17 minutes to form a primary ZnO film. Here, about 17 minutes is a time when only a 2D layer (two-dimensional layer) is produced. The process pressure is about 2 x 10 ^-2 torr. This is called the low temperature deposition step.

After the low temperature deposition step is performed, the power of the plasma power source 2 is turned off or weakly supplied, then the power for heating the substrate is increased to the desired temperature, and then the high temperature deposition step is performed to carry out the secondary on the primary ZnO film. A ZnO film is formed. The temperature of the high temperature deposition step is about 500 ° C. and is the same as the conditions of the low temperature deposition step except that the process temperature of the high temperature deposition step is higher than the process temperature of the low temperature deposition step.

In this example, the measured Θ-rocking half-width (FWHM) of the deposited thin film was 0.005 °, as shown in FIG. 2, and is much lower than the half-width 0.72 ° shown in Comparative Example 1 described below. to be. This means that the ZnO thin film deposited according to the embodiment of the present invention has a much higher degree of epitaxy than the thin film deposited according to the prior art. The surface roughness of the substrate was 28 kW, which was almost the same as that of the roughness 30 k shown in the comparative example. This means that by applying the technique used in the embodiment of the present invention, even by performing a high temperature deposition step of 500 ° C., it has the same roughness as a film deposited at a low temperature of 300 ° C.

In summary, when the ZnO thin film is deposited, only the two-dimensional layer is deposited in the low temperature deposition step, and the deposition is performed at a higher temperature than the low temperature deposition step in the high temperature deposition step, and the film quality of the deposited thin film is significantly improved. In more detail, the epitaxy of the thin film was improved and the roughness of the thin film was also improved. As shown in Fig. 2, when the two-stage deposition according to the present invention is carried out, the semi-conducting width is greatly reduced from 0.72 ° to 0.005 ° compared with the prior art. In addition, as shown in Figure 3, the thin film deposited according to the prior art can be seen that the intensity of the peak in the (002) and (101) surface is a polycrystalline thin film, whereas the thin film deposited according to the present embodiment It can be seen that the silver is a single-phase thin film because the intensity represents the peak only on the (002) plane. This means that the degree of epitaxy is significantly increased compared to the thin film deposited according to the prior art. 4 is a comparison of the roughness of the thin film, the roughness of the second ZnO thin film obtained by the two-step deposition according to this embodiment is 28 Å the same level as the first ZnO thin film deposited in one step at a low temperature of 300 ℃ the same conditions The roughness of (30Å) is shown. In addition, compared to the roughness (3000 kPa) of the thin film deposited in one step at a high temperature of 500 ℃ under the same conditions, the surface roughness is significantly improved.

In the above-described embodiment, the first process temperature of the low temperature deposition step is 300 ° C., the second process temperature of the high temperature deposition step is 500 ° C., but the first process temperature is 25-350 ° C., and the thickness of the ZnO film is 1-17. The same result as in Example 1 was obtained when the temperature was set to 200 Pa, the secondary process temperature, which is the high temperature deposition step, was set to 400 to 700 ° C., and the thickness of the ZnO film was 1 to 5 μm.

As described above, according to the present invention, when the sputtering is divided into two stages, when the first process is performed at a lower temperature than the first process at a lower temperature, the advantages of high temperature and low temperature at the time of thin film deposition are simultaneously obtained. As a result, the epitaxy of the thin film can be increased and the surface roughness can be improved.

Claims (2)

A method of forming a ZnO film on a sapphire substrate using a sputtering apparatus that generates a plasma having a ZnO target inside a vacuum chamber and a sapphire substrate arranged to face away from the ZnO target. A low temperature deposition step of forming a two-dimensionally grown primary ZnO film on the sapphire substrate while maintaining the temperature of the sapphire substrate at 25 to 350 ° C; And After the temperature of the sapphire substrate is raised to 400 ~ 700 ℃ a method of manufacturing a ZnO film using a sputtering deposition method comprising a high temperature deposition step of forming a secondary ZnO film on the primary ZnO film. The method for producing a ZnO film according to claim 1, wherein the primary ZnO film has a sputtering deposition method of 1 to 200 GPa.