JPH02198139A - Prevention of inner wall contamination of vacuum treatment apparatus - Google Patents

Abstract

PURPOSE:To reduce dust adhering to a treated wafer by a method wherein the inner wall of a preliminary vacuum chamber linked with a vacuum treatment chamber is covered with a plastic film which can be renewed by repairing. CONSTITUTION:The inner wall of a preliminary vacuum chamber 4 which protects a vacuum treatment chamber 2 from significant decline of a vacuum degree when a wafer 1 is taking into and out of the chamber 2 is covered with a plastic film 6 which can be renewed by repairing. Thus, by covering the inner wall of the preliminary vacuum chamber 4 linked with the vacuum treatment chamber 2 with the plastic film 6 which can be renewed by repairing, even if moisture in the air, residual reactive gas in the vacuum treatment chamber or the like penetrates into the chamber 4, as no metal part such as aluminum or stainless steel is exposed, creation of 'rust' caused by the inner wall contamination of the preliminary vacuum chamber can be avoided. With this constitution, dust adhering to the treated wafer can be reduced.

Description

[Detailed Description of the Invention] (Summary) Regarding a vacuum processing apparatus that performs various processes on a wafer in a vacuum state, particularly a method for reducing dust adhering to a wafer to be processed, vacuum processing for reducing dust adhering to a wafer to be processed The purpose of this invention is to provide a method for preventing contamination of the inner wall of an apparatus, and the inner wall of a pre-vacuum chamber connected to a vacuum processing chamber is covered with a plastic film that can be renewed by replacing the film.

[Industrial application field]

The present invention relates to a vacuum processing apparatus that performs various processes on wafers in a vacuum state, and particularly relates to a method for reducing dust adhering to wafers to be processed.

In the manufacture of semiconductor devices, vacuum processing equipment is used to perform various processes on wafers in a vacuum state, such as evaporation equipment and vapor phase growth equipment as a means of producing various thin films, and etching equipment and the like as a means of removing the produced thin films. is often used.

However, as semiconductor devices become more highly integrated, the patterns formed on each layer become finer, and the number of dust particles that adhere to the surface when various processes are applied to wafers in a vacuum condition affects the yield of processed wafers. It is becoming a factor. Therefore, it is desired to establish a method for reducing the generation of such dust.

[Conventional technology]

FIG. 3 is a schematic diagram showing the main parts of a conventional vacuum processing apparatus, and FIG. 4 is a time chart showing the operation of each part.

As shown in Fig. 3, the vacuum processing equipment used in the manufacture of semiconductor devices includes a vacuum processing chamber 2 for performing processes such as thin film generation and pattern formation on wafers 1, and a vacuum processing chamber 2 for supplying wafers to be processed and storing processed wafers. A preliminary vacuum chamber 4 is provided which connects the wafer cassette section 3 that performs the process, the vacuum processing chamber 2, and the wafer cassette section 3 placed in the atmosphere, and eliminates a significant drop in the degree of vacuum in the vacuum processing chamber 2 when the wafers 1 are removed. It is equipped with

The preliminary vacuum chamber 4 includes a first gate 41 provided between the wafer cassette section 3 and a second gate 42 provided between the vacuum chamber 2 and the wafer 1. When opening and closing the first gate 41 or the second gate 42, the preliminary vacuum chamber 4 is opened and closed when the first gate 41 is opened and closed.
The interior of the preliminary vacuum chamber 4 is brought to atmospheric pressure, and operations such as evacuating the interior of the preliminary vacuum chamber 4 are performed when opening and closing the second gate 42.

That is, the gas introduction system piping 43 that opens into the preliminary vacuum chamber 4 is connected to a nitrogen (N) gas supply source via the first cock 44.
A gas exhaust system piping 45 that opens into the preliminary vacuum chamber 4 is connected to a vacuum pump 5 such as a rotary pump via a second cock 46.
By opening and closing the cock 44 or the cock 46, the inside of the preliminary vacuum chamber 4 can be converted from a vacuum state to atmospheric pressure or from atmospheric pressure to a vacuum state.

In Figure 4, when transferring a wafer to be processed from the wafer cassette section to the vacuum processing chamber, first open the first cock to introduce Nz gas into the preliminary vacuum chamber, and when the pressure becomes close to atmospheric pressure, open the first gate. Open the chamber and transfer the wafer to be processed to the preliminary vacuum chamber. The first gate is closed as soon as the wafer to be processed is transferred to the pre-vacuum chamber. Next, open the second cock to turn on the N! in the pre-vacuum chamber. When the gas is exhausted and the vacuum state is near, the second gate is opened and the wafer to be processed is transferred to the vacuum processing chamber. The second gate is closed immediately after the wafer to be processed is transferred to the vacuum processing chamber.

In addition, when transferring processed wafers from the vacuum processing chamber to the wafer cassette section, first open the second cock to exhaust the N2 gas in the pre-vacuum chamber.
The gate is opened and the wafer to be processed is transferred to the preliminary vacuum chamber. The second gate is closed as soon as the wafer to be processed is transferred to the pre-vacuum chamber.

Next, the first cock is opened to introduce N2 gas into the preliminary vacuum chamber, and when the pressure becomes close to atmospheric, the first gate is opened and the wafer to be processed is transferred to the wafer setting section. The first gate is closed immediately after the wafer to be processed is transferred to the wafer cassette section.

As shown in FIG. 4, the period during which Nz gas is introduced and discharged in parallel is extremely short, but by separately providing the gas introduction system piping 41 and the gas exhaust system piping 42, the inside of the preliminary vacuum chamber 4 can be The gas flow is unidirectional, and as a result, the dust is discharged together with the Nz gas without being stagnant in the preliminary vacuum chamber 4.

Note that dust may adhere to the inner walls of the pre-vacuum chamber 4 or accumulate on the bottom, but when the inside of the pre-vacuum chamber 4 is returned to atmospheric pressure,
The flow rate of the two gases is kept low (hereinafter referred to as slow venting) to prevent the accumulated dust from flying up, thereby reducing the adhesion of dust to the wafer to be processed.

[Problem to be solved by the invention]

However, the pre-vacuum chamber is made of metal plates such as aluminum or stainless steel, and most of the dust that adheres to the inner walls or accumulates on the bottom of the pre-vacuum chamber is due to moisture in the atmosphere or residual reaction gas from the vacuum processing chamber. However, this is "rust" that occurs when the inner walls of the preliminary vacuum chamber become contaminated. Therefore, unless contamination of the inner wall is prevented, the amount of dust increases in proportion to the number of wafers processed, and there is a problem that the dust adhering to the wafer surface cannot be reduced by slow venting alone.

An object of the present invention is to provide a method for preventing contamination of the inner walls of a vacuum processing apparatus, which reduces dust adhering to wafers to be processed.

[Means to solve the problem]

FIG. 1 is a perspective view showing an embodiment of the pollution prevention method according to the present invention. The same objects are represented by the same symbols throughout the plan.

The above-mentioned problem is achieved by the method for preventing contamination of the inner wall of a vacuum processing apparatus according to the present invention, in which the inner wall of the preliminary vacuum chamber 4 connected to the vacuum processing chamber 2 is covered with a plastic film 6 that can be renewed by changing the film. .

[For production]

In Figure 1, the inner wall of the pre-vacuum chamber connected to the vacuum processing chamber is covered with a plastic film that can be replaced and replaced, thereby preventing moisture in the atmosphere and residual reaction gas from the vacuum processing chamber from entering. However, it is possible to realize a method for preventing contamination of the inner wall of a vacuum processing apparatus, which eliminates the occurrence of ``rust'' caused by contamination of the inner wall of the preliminary vacuum chamber and reduces dust adhering to the wafer to be processed.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings. Note that FIG. 2 is a diagram showing the effect of the pollution prevention method according to the present invention.

As shown in FIG. 1, the method for preventing contamination on the inner wall of a vacuum processing apparatus according to the present invention includes a vacuum processing chamber 2 in which a wafer 1 is subjected to processing such as thin film generation and pattern formation, and a vacuum processing chamber 2 in which wafers to be processed are supplied and processed wafers are stored. The inner wall of the preliminary vacuum chamber 4, which connects the wafer cassette section 3 that performs the wafer cassette processing and prevents a significant decrease in the degree of vacuum in the vacuum processing chamber 2 when the wafers 1 are removed, is covered with a plastic film 6 that can be renewed by changing the wafer cassette section 3. There is.

In this way, the inner wall of the preliminary vacuum chamber 4 connected to the vacuum processing chamber 2 is covered with the plastic film 6, which can be renewed by replacing the film, so that moisture in the atmosphere and residual reaction gases in the vacuum processing chamber can be removed. Even if an intrusion occurs, metal parts such as aluminum or stainless steel are not exposed, so there is no possibility of rust occurring due to contamination of the inner wall of the preliminary vacuum chamber.

Incidentally, according to experiments conducted by the inventors, in the case of conventional vacuum processing equipment, the amount of dust of 0.3 μm adhering to the wafers being processed increases in proportion to the increase in the number of wafers being processed, as shown by the broken line in Figure 2. On the other hand, in the case of vacuum processing equipment to which the contamination prevention method of the present invention is applied, as shown by the solid line in the same figure, the amount of dust of 0.3 μm that adheres to the wafers to be processed increases. It remains almost constant regardless. That is, it is possible to realize a method for preventing contamination of the inner wall of a vacuum processing apparatus that reduces dust adhering to a wafer to be processed.

It should be noted that there is dust other than 'rust' that occurs due to contamination of the inner walls of the preliminary vacuum chamber, and as the number of wafers to be processed increases, these dusts accumulate on the plastic film, causing dust that adheres to the wafers to be processed. It is also conceivable to increase the amount of However, in such a case, by replacing the plastic film, it is possible to clean the inside of the preliminary vacuum chamber in an extremely short time.

FIG. 2 is a diagram showing the effect of the contamination prevention method according to the present invention. FIG. 3 is a schematic diagram showing the main parts of a conventional vacuum processing apparatus. FIG. 4 is a time chart showing the operation of each part. , is. In the figure, ■ represents a wafer, 2 represents a vacuum processing chamber, 3 represents a wafer cassette section, 4 represents a preliminary vacuum chamber, and 6 represents a plastic film.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide a method for preventing contamination of the inner wall of a vacuum processing apparatus, which reduces dust adhering to a wafer to be processed.

[Brief explanation of the drawing]

Figure 1 shows an embodiment of the pollution prevention method according to the present invention.

Claims (1)

[Claims] A preliminary vacuum chamber (2) connected to at least the vacuum processing chamber (2)
4) A method for preventing contamination of an inner wall of a vacuum processing apparatus, characterized in that the inner wall of the item (6) is covered with a plastic film (6) that can be renewed by changing the film.