JPH0673536A - Formation of transparent and stable coating film - Google Patents

Abstract

PURPOSE:To provide an ion plating method which forms a dense, transparent and stable oxide coating film on a substrate surface by nearly removing moisture from an atmosphere at the time of film formation. CONSTITUTION:The plasma generated by using an inert gas having purity of 100ppb order with respect to moisture by a pressure gradient type plasma generator 2 having a cathode consisting of LaB6 is introduced into a vacuum vessel 1 kept under the ultimate pressure of 10<-8>Torr order. This plasma is introduced into an aluminum block or silicon block 5 in the vacuum vessel 1, by which aluminum or silicon is evaporated and is ionized in the plasma. Gaseous oxygen having the purity nearly equal to the purity of the inert gas with respect to the moisture is introduced into the vacuum vessel 1 in order to generate the oxide of the aluminum or silicon by reacting with the ions of the aluminum or silicon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a thin film of a metal oxide on the surface of various substrates by ion plating, and in particular, by improving the atmosphere during film formation, a dense and transparent film is formed on the surface of the substrate. The present invention relates to a method for forming a transparent stable film that forms

[0002]

2. Description of the Related Art In recent years, an aluminum alloy vacuum container is often used in semiconductor manufacturing equipment and the like.
In the semiconductor manufacturing process, corrosive gas is often used, which causes a problem in corrosiveness of aluminum alloys. Therefore, measures have been taken to improve the corrosion resistance by forming an aluminum oxide film on the surface of the aluminum alloy.

Conventionally, an anodizing treatment has been adopted as a method for forming an aluminum oxide film on the surface of an aluminum alloy.

On the other hand, when a plastic film is used for a vacuum pack, gas permeation occurs through minute holes existing in the plastic film, and food, cleaning, precision electronic parts, etc. enclosed in the plastic film are stable for a long period of time. There is a problem that it cannot be saved. The same problem also occurs when a plastic film is used as a window when introducing microwaves into a vacuum. Therefore, forming a stable film as a gas barrier that suppresses gas permeation on the surface of the plastic film is considered, and some attempts have been made.

[0005]

By the way, in the above-mentioned conventional method for forming an aluminum oxide film on the surface of an aluminum alloy by anodizing treatment, the aluminum oxide film contains a porous water content, and in the high vacuum region, gas is generated. There is a problem that the vacuum characteristics are deteriorated due to the release, and the corrosion resistance is not sufficient due to lack of denseness.

When the above aluminum alloy is heated,
Due to the difference in the coefficient of thermal expansion between the aluminum alloy and the aluminum oxide coating, fine cracks are generated in the stable coating, and the corrosion resistance is extremely deteriorated.

On the other hand, the stable film as a gas barrier formed on the surface of the plastic film described above is preferably transparent to visible light, microwaves of microwave ovens, and general microwaves. No suitable method has yet been established for forming a colorless transparent transparent stable film at a certain low temperature and in large quantities on an industrial scale.

The present invention is intended to solve such a problem, and employs a pressure gradient type plasma generator having a LaB ₆ cathode as an ion source to achieve an ultimate pressure of 10
^-A dense and transparent sapphire-like coating on the surface of the base material in the vacuum container by reactive ion plating with oxygen gas using a high-purity gas with a water content of 100 ppb or less in a vacuum container of ⁸ Torr level A transparent stable coating capable of forming a stable coating such as a film having a sloped coefficient of thermal expansion by controlling the flow rate of the oxygen gas introduced into the vacuum vessel. An object is to provide a forming method.

[0009]

In order to achieve the above-mentioned object, the method for forming a transparent stable film of the present invention has an ultimate pressure of 10 ^-8.
The pressure gradient plasma generator with a LaB ₆ cathode was used to store 10
A plasma generated by using an inert gas having a purity of 0 ppb level is introduced, and the plasma is guided to an aluminum block in the vacuum container to evaporate aluminum and ionize it in the plasma. The surface of the base material previously placed in the vacuum container by introducing into the vacuum container an oxygen gas having a purity almost equal to that of the above inert gas with respect to water so as to generate aluminum oxide by reacting with The feature is that a dense and transparent sapphire-like film is formed on.

The method for forming a transparent stable film of the present invention is
A material containing aluminum as a main component is used as the base material, and an intermediate layer having a coefficient of thermal expansion that gradually changes is formed between the material and the dense and transparent sapphire-like coating so that the oxygen gas It is characterized in that the flow rate of introduction into the vacuum container is controlled to be gradually increased.

Further, the method for forming a transparent stable film of the present invention is
Using a metal material having a smaller thermal expansion coefficient than aluminum as the base material, so that an intermediate layer having a gradually changing thermal expansion coefficient is formed between the metal material and the dense and transparent sapphire coating. The present invention is characterized in that control is performed such that the flow rate of the oxygen gas introduced into the vacuum container is gradually increased.

The method for forming a transparent stable film of the present invention is
Inside the vacuum vessel whose ultimate pressure is kept at 10 ^-8 Torr, L
By introducing a plasma generated by using a pressure gradient type plasma generator having an aB ₆ cathode with an inert gas having a purity of about 100 ppb with respect to water and guiding the plasma to the silicon block in the vacuum container, In order to vaporize silicon and ionize it in the plasma, and to react with the ions of the silicon to generate silicon oxide, oxygen gas having a purity almost equal to that of the inert gas with respect to water is introduced into the vacuum container. By doing so, a dense and transparent quartz-like coating is formed on the surface of the base material which is previously placed in the vacuum container.

[0013]

In the method of forming the transparent stable film of the present invention, the aluminum in the vacuum container is first evacuated by the plasma generated by the plasma generator having the cathode of LaB6 after the vacuum container is evacuated to the level of 10 ^-8 Torr. Alternatively, silicon is heated and evaporated, and ionized in the plasma. Then, while reacting with oxygen ions introduced into the vacuum vessel, an action of depositing a dense and transparent stable film on the surface of the base material placed in the vacuum vessel is performed.

Further, by controlling the flow rate of oxygen introduced into the vacuum container, the effect of changing the thermal expansion coefficient of the coating film formed is performed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for forming a transparent stable film as an embodiment of the present invention will be described below with reference to the drawings. FIG.

As shown in FIG. 1, the film forming apparatus for this embodiment is designed so that a high-level exhaust system 12 is used to evacuate to an ultimate pressure of 10 ⁻⁸ Torr through a vacuum pump connection 7. There is. The vacuum vessel 1 is a pressure gradient type plasma generator 2 capable of introducing plasma into the vessel (Japanese Patent Laid-Open Publication No. Sho.
58-73770) and the oxygen gas inlet 6 in the vacuum vessel 1.
And an oxygen gas introduction flow rate control device 11 capable of introducing a certain flow rate of oxygen gas through the.

The pressure gradient type plasma generator 2 is provided with a cooling water connecting port 9 for cooling the device during operation and a carrier gas introducing port 8 for introducing an inert gas. This pressure gradient type plasma generator 2 is LaB6
It has a cathode and is capable of generating plasma using an inert gas having a purity of about 100 ppb with respect to the water introduced from the carrier gas inlet 8.

The vacuum container 1 has a cooling water connection port 9 for installing the block 5 melted by the plasma.
Between the material 5 and the base material 4 to be melted, which has a water-cooling crucible 3 with a mounting base N for pivotally mounting the base material 4 by a motor M or the like provided outside the vacuum container 1. A shutter 10 is provided in the. With such a configuration, in the transparent stable film forming method of the present embodiment, when an aluminum block is used as the melted block 5, first, the ultimate pressure is evacuated to 10 ⁻⁸ Torr and the vacuum vessel 1 is evacuated to The plasma generated by the gradient plasma generator 2 is introduced into the vacuum container 1, and aluminum is evaporated by the plasma to be ionized in the plasma.

On the other hand, an oxygen gas having a purity of about 100 ppb with respect to water is introduced from the oxygen gas inlet 6. The shutter between the aluminum block 5 and the base material 4
By moving 10 and reacting the same oxygen gas with the aluminum ions, a dense and transparent sapphire-like film is formed on the surface of the base material 4.

When a silicon block is used as the melted block 5, a dense and transparent quartz film is formed on the surface of the base material 4 by the same method. In order to form a uniform film on the surface of the base material 4, the base material 4 may be turned by the motor M via a turning mechanism.

According to the transparent stable film forming method of this embodiment, the vacuum container 1 is evacuated to the ultimate vacuum degree of 10 ⁻⁸ Torr to remove water and a gas having a high purity is used. A dense and transparent sapphire-like coating or a quartz-like coating can be formed on the surface of the base material 4 at a low temperature of about ° C. Therefore, it becomes possible to form a dense and stable film as a gas barrier even on a plastic film which is a material that is easily affected by heat. Since this stable coating is transparent to microwaves, the plastic film with a stable coating is effective for applications such as vacuum packs for foods and windows for introducing microwaves into vacuum.

When an aluminum block is used as the melting block 5 and a material containing aluminum as a main component (aluminum alloy) or a metal material having a thermal expansion coefficient smaller than that of aluminum is used as the base material 4, the base material is used. An intermediate layer whose coefficient of thermal expansion gradually changes from that of the base material to that of the sapphire-like film is formed between the dense and transparent sapphire-like film deposited on the outermost surface of the film formed above. First, the flow rate of oxygen gas is controlled so as to be gradually increased.

As a result, when an aluminum oxide film is formed on an aluminum alloy for a conventional vacuum container by anodic oxidation or another method, it is caused by a mismatch of thermal expansion coefficients between the aluminum alloy and the aluminum oxide film. Since the problem of cracking that has been solved is solved by the presence of the intermediate layer, it is possible to realize a highly reliable aluminum alloy vacuum container having a stable and stable coating, which has corrosion resistance.

Of course, such a dense and transparent stable coating is applied not only to the above-mentioned plastic film and aluminum alloy but also as a surface coating of a material which is required to have high corrosion resistance and sealing property.

[0025]

As described above in detail, according to the method for forming a transparent stable film of the present invention, it is possible to form a stable and dense sapphire-like or quartz-like film at low temperature. It is possible to form a stable film having sufficient denseness as a gas barrier and transparency capable of transmitting microwaves even on a plastic film used for a vacuum pack or the like which is easily affected. Further, on the surface of a metal material having a smaller thermal expansion coefficient than aluminum alloy or other aluminum, an intermediate layer having a gradually changing thermal expansion coefficient is provided between the base material and the outermost surface sapphire-like coating. It is possible to solve the problem of cracking which causes a difference in thermal expansion coefficient between the base material and the sapphire-like coating when the base material is heated, and to provide a stable coating having high reliability and high corrosion resistance.

[Brief description of drawings]

FIG. 1 is an apparatus configuration diagram for a method for forming a transparent stable film as an embodiment of the present invention.

[Explanation of symbols]

1 Vacuum container 2 Pressure gradient type plasma generator 3 Water cooling crucible 4 Base material 5 Melting block (aluminum or silicon) 6 Oxygen gas 7 Vacuum pump connection port 8 Carrier gas introduction port 9 Cooling water connection 10 Shutter 11 Oxygen gas introduction flow rate control Device 12 Exhaust system M motor N mounting base

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yoshinori Takahashi 2-17-15 Tsukuda, Chuo-ku, Tokyo Tsukishima Kikai Co., Ltd.

Claims (4)

[Claims] 1. An inert gas having a purity of 100 ppb with respect to water content is generated by a pressure gradient type plasma generator having a LaB ₆ cathode inside a vacuum container whose ultimate pressure is kept at 10 ⁻⁸ Torr. Introducing the plasma that has been introduced, by introducing the plasma to the aluminum block in the vacuum container to evaporate the aluminum and ionize it in the plasma, and to react with the ions of the aluminum to produce aluminum oxide, By introducing an oxygen gas having a purity substantially equivalent to that of the inert gas with respect to water content into the vacuum container, to form a dense and transparent sapphire-like film on the surface of the base material previously placed in the vacuum container. A method for forming a transparent stable film, which comprises: 2. A material containing aluminum as a main component is used as the base material, and an intermediate layer having a gradually changing thermal expansion coefficient is formed between the material and the dense and transparent sapphire-like coating. The method for forming a transparent stable film according to claim 1, wherein the flow rate of introducing the oxygen gas into the vacuum container is controlled to be gradually increased. 3. A metal material having a coefficient of thermal expansion smaller than that of aluminum is used as the base material, and an intermediate layer having a gradually changing coefficient of thermal expansion is formed between the metal material and the dense and transparent sapphire coating. The method for forming a transparent stable film according to claim 1, wherein the flow rate of the oxygen gas introduced into the vacuum container is controlled to be gradually increased as described above. 4. An inert gas having a purity of about 100 ppb with respect to water content is generated by a pressure gradient type plasma generator having a LaB ₆ cathode inside a vacuum container whose ultimate pressure is maintained at about 10 ⁻⁸ Torr. Introduced plasma, which is introduced into the vacuum chamber to introduce silicon into the silicon block in the vacuum vessel to vaporize silicon and ionize it in the plasma, and to react with the ions of the silicon to generate silicon oxide, Forming a dense and transparent quartz-like film on the surface of the base material previously placed in the vacuum container by introducing oxygen gas having a purity substantially equal to that of the inert gas with respect to water content into the vacuum container. A method for forming a transparent stable film, which comprises: