JPH02259064A - Method for removing deposited film in vacuum thin film forming equipment - Google Patents

Abstract

PURPOSE:To efficiently remove the thin film deposited on the surface of the vacuum thin film forming equipment made of stainless steel by previously forming a coating film of Ni, Cr, iron or their alloy on the surface. CONSTITUTION:A coating film of Ni, Cr and iron or their alloy is previously formed on the surface of the vacuum thin film forming equipment made of stainless steel. After a thin film is formed, the coating film is dissolved, and the thin film deposited on the coating film surface when the film is formed is removed. In addition, although the coating film can be easily formed by wet plating such as electroless plating and electroplating and vacuum physical vapor deposition such as vacuum deposition and sputtering, wet plating is preferably used from the standpoint of ease and cost. When the equipment is dipped in a liq. solubilizer, the solubilizer infiltrates from pinholes or the part free of the depositing film, and the depositing film is efficiently dissolved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for easily removing a thin film adhering to the surface of vacuum thin film forming equipment. Here, the vacuum thin film forming equipment refers to various vacuum thin film forming apparatuses and jigs.

[Prior Art] Vacuum deposition, ion plating, sputtering, CVD, and other devices are known as vacuum thin film forming devices.

All of these devices have a vacuum container and supply substances that become thin film materials in the form of steam, ions, or compound gases under vacuum or low pressure conditions to form a thin film on the surface of the object to be treated. be. When forming a thin film using these devices, in order to obtain a high-quality thin film, the inside of the vacuum container is once evacuated to a high vacuum before performing the vacuum thin film forming process. The materials of the vacuum container and the jigs used in the vacuum container have low vapor pressure, do not easily react with other substances, and are heat resistant. Stainless steel is mainly used because it is not particularly difficult to process and is relatively inexpensive and easily available.

The material of the thin film to be formed includes, for example, silicon, carbon,
Chromium nitride, titanium, titanium nitride, etc. are used,
When forming various thin films on the object to be processed, the thin film also adheres to surfaces of the vacuum thin film forming equipment other than the object to be processed, such as the surface of the jig and the inner surface of the vacuum container. As the film adheres, the surface area increases, and the amount of gas adsorbed and released in the vacuum container of the vacuum thin film forming equipment increases, resulting in a decrease in the degree of vacuum in the vacuum container and a longer evacuation time to reach the specified degree of vacuum. This leads to a decrease in the quality of the formed thin film and a decrease in efficiency due to a prolonged processing time. In addition, this adhered film may impede the mechanical operation of shutters, movable jigs, etc., or may adhere to the thin film formed by peeling, degrading its quality. For this reason, periodic removal of the adhered film has become an important task.

The removal method is as follows: a) Scrape off the attached thin film with a grindstone or sandpaper b) Dissolve the attached thin film with a solution such as acid C) Form an aluminum thin film on the surface of the vacuum thin film forming equipment in advance, The adhering film is removed by dissolving the aluminum thin film by immersing it in alkaline solution (Special Publication No. 1983-1966).
901) etc.

[Problems to be solved by the invention] Method a): 1) requires a large amount of work time; This is remarkable when the deposited film has good adhesion and excellent wear resistance.

2) Damage to the surface of the vacuum thin film forming equipment.

There is a drawback.

In method b), 1) If the deposited film is made of a material that is difficult to dissolve, it will take a long time to dissolve, or if it is made of a material that is extremely difficult to dissolve (for example, C, SiC, Si3N4, etc.) , it may be virtually impossible to remove by dissolution.

2) Since the surface of the vacuum thin film forming equipment is immersed in the solution for a long time, there is a possibility that it will dissolve.

In method C), an aluminum thin film is formed on the surface of the vacuum thin film forming equipment, so 1) The melting point of aluminum is relatively low (660°C), so the operating temperature is lower than when no aluminum thin film is formed. limited.

2) The aluminum in the thin film diffuses onto the surface of the vacuum thin film forming equipment in which it was formed, degrading the surface of the vacuum thin film forming equipment.

There are drawbacks such as.

The present invention has been made in view of the drawbacks of the conventional methods described above, and an object of the present invention is to provide a method that can efficiently remove thin films attached to vacuum thin film forming equipment.

[Means for Solving the Problems] That is, the present invention provides a method of forming a coating made of nickel, chromium, iron, or an alloy thereof on the surface of a vacuum thin film forming equipment made of stainless steel, and then performing a thin film forming process. After performing, by dissolving the coating,
The gist of the present invention is a method for removing an adhered film in vacuum thin film forming equipment, which is characterized by removing a thin film adhered to the surface of a film through a thin film forming process.

The details will be explained below.

A coating made of nickel, chromium, iron, or an alloy thereof can be easily formed by wet plating such as electroless plating or electroplating, vacuum physical vapor deposition such as vacuum evaporation, or sputtering. Wet plating is preferred because the coating can be formed easily and inexpensively. The reason why we include not only single metals but also their alloys is that similar effects can be obtained with alloys such as nickel-iron plating, which is used instead of nickel plating.

The film thus formed is dissolved by immersing the vacuum thin film forming equipment in a dissolving solution. The solution enters through pinholes existing in the thin film attached to the surface of the coating or from areas where the thin film is not formed on the surface of the coating, and dissolves the coating. At this time, instead of simply immersing the material in the solution, the side to be dissolved may be used as an anode and a current may be applied to dissolve the material by electrolysis, or this effect may be used to promote dissolution.

The dissolving liquid may be any solution as long as it can dissolve the coating and not dissolve the stainless steel base material or dissolve the coating material preferentially over the stainless steel. These solutions are appropriately selected and used depending on the components of the film to be formed; for example, nitric acid, sulfuric acid + H2O2 for nickel, hydrochloric acid, Na OH + Ka (Fe CCN) 6) for chromium,
Nitric acid, sulfuric acid, etc. can be used for iron.

The thickness of the coating is arbitrarily determined depending on usage conditions such as the interval at which the adhered film is removed, the ease with which the formed thin film diffuses into the coating and the stainless steel base material, and the usage temperature. For example, if a film is formed of a material that easily diffuses at high temperatures and the adhered film is not removed for a long period of time, a thick film is required. When removing an attached film, the film does not need to be particularly thick.

Further, the thicker the film, the easier it is to dissolve from the parts to which the thin film is not attached. However, once the thickness exceeds a certain level, the effect does not change much even if the thickness is increased.

For this reason, it is considered appropriate to select the film thickness in the range of several thousand to several tens of micrometers depending on the usage conditions.

[Function] By forming a coating made of nickel, chromium, iron, or an alloy thereof on the vacuum thin film forming equipment in advance, the thin film that adheres when forming the thin film will be attached to the base material of the vacuum thin film forming equipment. Instead, it adheres to this coating. Therefore, by dissolving and removing the coating, the attached thin film can be easily removed.

Since there are pinholes in the thin film, if the vacuum thin film forming equipment used to remove the thin film is immersed in a dissolving solution that can dissolve the film, a thin film will be formed through the pinholes existing in the thin film or on the surface of the film. The solution can enter from the untreated areas and dissolve the coating.

At this time, since the coating is made of an easily soluble material, the time required for dissolution is short, and the coating is preferentially dissolved over the base stainless steel, so that the base stainless steel is less likely to dissolve.

The material of the coating can be used in a vacuum container at a temperature equal to or higher than that of the stainless steel base material, does not melt, and is a component of stainless steel, so it will not diffuse into the stainless steel base material or will not diffuse into the stainless steel base material. There is no negative effect.

[Example] Hereinafter, the present invention will be explained in more detail based on Examples.

A nickel film was electroplated in advance to a thickness of 3μ on a stainless steel disc-shaped sample holder with a diameter of about 7an.
A pipe-shaped sample was placed on a sample holder as an object to be processed, heated to 300° C., and subjected to sputtering to form a chromium nitride film, and then the sample holder was immersed in nitric acid for 3 hours.

A chromium film with a thickness of 1 μm was formed in advance on a disc-shaped stainless steel sample holder with a main diameter of approximately 7 marks by sputtering, and a pipe-shaped sample was placed on the sample holder as an object to be treated, and then sputtered using sputtering. After performing the alumina film formation treatment, this sample holder was immersed in hydrochloric acid for 2 hours.

An iron film was electroplated to a thickness of 10 μm in advance on a disc-shaped stainless steel sample holder with a diameter of approximately 7 mm, and a pipe-shaped sample was placed on the sample holder as a physical object. After heating to 500° C. to form a titanium carbide film by sputtering, the sample holder was immersed in sulfuric acid for 4 hours.

A chromium film was electroplated in advance to a thickness of 4 μm on a disc-shaped stainless steel sample holder with a diameter of about 7 cm.
A pipe-shaped sample is placed on a sample holder as an object to be processed, heated to 300°C, and a chromium nitride film is formed by sputtering. Immerse it in a solution and use anodic oxidation to make the holder side the anode.
A current was applied for 2 hours to dissolve the chromium film.

Using a disc-shaped stainless steel sample holder with a diameter of about 7 mm, a pipe-shaped sample is placed on the sample holder as the object to be treated, heated to 300°C, and chromium nitride is applied by sputtering. After the film formation process was performed, an attempt was made to scrape off the adhered film on the sample holder using a belt sander or sandpaper.

Using a disc-shaped stainless steel sample holder with a main diameter of about 7 ann, a pipe-shaped sample was used as the object to be processed.
The sample was placed on a sample holder and heated to 300°C to form a chromium nitride film by sputtering, and then the sample holder was immersed in hydrochloric acid, sulfuric acid, and nitric acid for 120 hours.

Failure 1 Using a disc-shaped stainless steel sample holder with a diameter of 7 cm, place a pipe-shaped sample as the object to be treated on the sample holder, heat it to 300°C, and form a chromium nitride film by sputtering. After this, the sample holder was immersed in fluoronitric acid.

A disk-shaped stainless steel sample holder with a diameter of approximately 7mm. An aluminum film was formed in advance with a thickness of 4 μm by sputtering, and a pipe-shaped sample was used as the object to be processed.
The sample was placed on a sample holder, heated to 300° C., and a chromium nitride film was formed by sputtering.

[Effects of the Invention] In Examples 1, 2, and 3.4, the attached film could be easily removed, and there was no abnormality in the holder.

In Comparative Example 1, since the chromium nitride film has excellent wear resistance, it took 8 hours to remove the film that had adhered to the sample holder to a thickness of about 20 μm, and the holder was also damaged. Comparative example 2
Almost no chromium nitride was dissolved. In Comparative Example 3, the chromium nitride was dissolved, but the holder was also dissolved. In Comparative Example 4, the aluminum film melted and the holder and part of the sample were welded together.

As described above, according to the present invention, it is possible to easily remove a thin film that adheres to the surface of the vacuum thin film forming equipment without being subject to new restrictions on the operating temperature and without damaging the surface of the vacuum thin film forming equipment. It is possible to improve efficiency.

Claims (1)

[Claims] A thin film is formed by forming a film made of nickel, chromium, iron, or an alloy thereof on the surface of vacuum thin film forming equipment made of stainless steel, and then melting the film after performing a thin film forming process. A method for removing an adhered film in vacuum thin film forming equipment, the method comprising removing a thin film adhered to a film surface through processing.