JPH05263229A - Production of aluminum oxide thin film - Google Patents

Abstract

PURPOSE:To form an Al2O3 thin film on a substrate at a high rate by sputtering by performing reactive sputtering with an Al-Al2O3 mixture as a target. CONSTITUTION:A target consisting of an Al-Al2O3 mixture is used, and reactive sputtering utilizing a sputtering gas of Ar, etc., contg. O2 as a gaseous reactant is performed to form an Al2O3 thin film as the protecting or insulating film for the thin-film element on the surface of a substrate. In this case, a target contg. >=30vol.% Al or 50-95vol.% Al and the balance Al2O3 is used to form an Al2O3 thin film at a high rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an aluminum oxide thin film having a significantly improved film forming rate.

[0002]

2. Description of the Related Art Aluminum oxide thin films are often used as protective films and insulating films for thin film elements and the like, and a method of forming an aluminum oxide thin film by a sputtering method that can form a film at a low temperature is often used. There is.

Conventionally, when such a metal oxide thin film is formed by a sputtering method, a reactive sputtering method in which the oxide is directly used as a target or a metal is used as a target and oxygen or the like is used as a reactive gas is known. It is used. When aluminum oxide is used directly as a target, since aluminum oxide is an insulator, current does not flow in the DC bias method,
A high frequency sputtering method is used. When metallic aluminum is used as the target, a reactive sputtering method utilizing the reaction with oxygen mixed in the discharge gas is used.

[0004]

In the sputtering method using such a simple substance of aluminum or a simple substance of aluminum oxide as a target material, the film formation rate is slow, which adversely affects the cost and process time when forming a thin film. For this reason, how to improve the film forming speed has become a big problem.

In general, as a method for improving the film forming speed, proposals have been made to increase the power output of the power source or to improve the target itself for improving the cooling performance. However, there are problems such as complicated device structure and increased power consumption. An object of the present invention is to provide a method of manufacturing an aluminum oxide thin film, which overcomes the above-mentioned drawbacks of the prior art and can obtain a large film formation rate without complicating the apparatus or target structure or increasing the power consumption. Especially.

[0006]

The present invention has been made in order to achieve the above-mentioned object, and replaces the conventional target material of aluminum alone or aluminum oxide alone,
The present invention provides a method for producing an aluminum oxide thin film, which comprises depositing an aluminum oxide thin film by a reactive sputtering method using a target made of a mixture of aluminum and aluminum oxide (Al2 O3).

As a method for producing an aluminum oxide thin film, the target material of the present invention is a mixed target material of metal and oxide, so that the reactive sputtering method utilizing the reaction with oxygen mixed in the sputtering gas is desirable. ..
Furthermore, although a direct current and high frequency sputtering method can be used, it is preferable to use the high frequency sputtering method in order to secure the stability of the discharge state.

Further, the sputtering conditions when using the mixed target material are the same as those when using the target material of aluminum alone or aluminum oxide alone, but the film can be formed at a sufficiently high speed, but a thin film is formed at a higher film forming speed. For example, as shown in Table 1, it is more effective if the ratio of the flow rate of argon and oxygen is 5: 1 and the pressure is 2 mTorr.

[0009]

[Table 1]

When the film is formed by the sputtering method as described above, the thin film obtained is amorphous.

On the other hand, although an arbitrary value can be applied to the mixing ratio of aluminum and aluminum oxide of the mixed target material, it is necessary to obtain a high-density target for ensuring the stability of the discharge state during sputtering, and a further remarkable film formation rate. In order to obtain the improvement, it is desirable that the aluminum content is 30% by volume or more, preferably 50 to 95% by volume.

[0012]

【Example】

Example 1 FIG. 1 shows a soda-lime-silica glass plate on which an aluminum oxide thin film was formed by a high frequency sputtering method using a conventionally used simple substance of aluminum, a simple substance of aluminum oxide and a mixture of aluminum and aluminum oxide according to the present invention as target materials. It is a graph which compared the film-forming speed at the time of forming a film on it. As the sputtering gas, a mixed gas of argon and oxygen was used. As the mixed target material according to the present invention, a mixed target having a volume ratio of aluminum to aluminum oxide of 9: 1 was used.

Comparing the film formation rate of the aluminum oxide thin film obtained with the gas pressure kept constant at 5 mTorr with that of the conventional target material, the target was 2.1 times that of the aluminum single target and 1.4 times that of the aluminum oxide single target. Doubled.

Example 2 FIG. 2 shows a film formation rate when an aluminum oxide thin film was formed on a soda lime silica glass plate by a high frequency sputtering method using the mixed target according to the present invention and aluminum contained in the mixed target material. It shows the relationship of the content of. As the sputter gas, a mixed gas having an argon / oxygen flow rate ratio of 9: 1 was used, and the gas pressure was 5 mTo.
It was fixed at rr. Aluminum oxide alone, which is a conventional technique, when the aluminum content is 0 in volume%, 100%
The case is the film forming rate when using a target of aluminum alone. Comparing the film forming rate of the obtained aluminum oxide thin film with that of the prior art and that of the present invention, an increase in the film forming rate is observed in the region where the aluminum content is 30% by volume or more.

[0015]

According to the present invention, there is an advantage that a film formation rate of an aluminum oxide thin film is significantly improved by forming a film by a reactive sputtering method using a composite target which is a mixture of aluminum and aluminum oxide. ..

Further, the method for producing an aluminum oxide thin film using the composite target material of the present invention can be applied to various sputtering apparatuses currently in practical use, and the film forming rate of the aluminum oxide thin film can be increased under the same conditions as the conventional target. Significantly contributes to productivity and economic improvement.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the aluminum content (volume%) of a target and the film formation rate (μm / hour).

Claims (3)

[Claims] 1. A method for producing an aluminum oxide thin film, which comprises depositing an aluminum oxide thin film by a reactive sputtering method using a target made of a mixture of aluminum and aluminum oxide. 2. The method for producing an aluminum oxide thin film according to claim 1, wherein the target contains 30% by volume or more of aluminum. 3. The method for producing an aluminum oxide thin film according to claim 1, wherein the target contains 50 to 95% by volume of aluminum.