JPH11176794A - Wet cleaning device for electronic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate occurrence of bubbles in a cleaning bath, by a method wherein a deairing device is provided in a cleaning agent circulation line in a wet cleaning device for an electronic material. SOLUTION: An embodiment comprises a batch type cleaning bath 1, and a cleaning agent circulation line 3 which extracts a cleaning agent by a circulation pump 2 near the cleaning bath and returns again to the cleaning bath, and a deairing device 4 and a purifying device 5 of a cleaning agent are provided in a cleaning agent circulation line. In this deairing device 4, a gas transmitting film module is connected to a vacuum pump 6, and a filter is used in a cleaning device 5 of a cleaning agent. Here, the cleaning agent extracted from the batch type cleaning bath 1 is supplied with pressure by the circulation pump 2, and is returned again to the cleaning bath 1 through the deairing device 5 and the purifying device 5 of the cleaning agent. As the deairing device 4 is provided in the cleaning agent circulation line, a gas component dissolved in the cleaning agent is reduced to a degree of saturation or less in atmospheric pressure, with the result that occurrence of gas in the cleaning bath can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a wet cleaning apparatus for electronic materials. More particularly, the present invention relates to a wet cleaning apparatus for electronic materials for cleaning the surface of electronic materials such as silicon substrates for semiconductors and glass substrates for liquid crystals.

[0002]

2. Description of the Related Art Cleaning solutions for electronic materials include RCA cleaning solutions based on hydrogen peroxide, ultrapure water itself, and acids, alkalis, oxidizing agents, reducing agents, and the like. Adjusted ultrapure water is used.
In the batch-type wet cleaning method, a circulation system is used in which the cleaning liquid is drawn out of the cleaning tank by a pump and supplied to the cleaning tank again after being filtered by a filter in order to reduce consumption of the cleaning liquid. In recent years, a membrane module having an ion exchange function has made it possible to remove metal impurities in a cleaning solution, and the use of a circulation system has been spreading more and more. When an electronic material is cleaned using a cleaning liquid for an electronic material, gas may be dissolved in the cleaning liquid. In particular, in a system in which the cleaning liquid is circulated and used, a pressurized or depressurized state is more or less generated, and bubbles are easily generated in the cleaning liquid. In the case where the components of the cleaning liquid are decomposed and gasified, bubbles are easily generated. For example, in a cleaning solution containing hydrogen peroxide, the hydrogen peroxide self-decomposes into oxygen, and bubbles are easily generated. When air bubbles are generated in the cleaning liquid, there is a problem that fine air bubbles adhere to the surface of the electronic material, which is the object to be cleaned, and contaminate the object to be cleaned with foreign substances that collect on the surface of the bubbles. In particular, in the case of a cleaning liquid containing hydrofluoric acid, the cleaned solid surface becomes hydrophobic, air bubbles easily adhere to the solid surface, and the solid surface is likely to be re-contaminated.

[0003]

SUMMARY OF THE INVENTION The present invention provides an electronic material wet cleaning process for cleaning the surface of an electronic material such as a silicon substrate for a semiconductor or a glass substrate for a liquid crystal. An object of the present invention is to provide a wet cleaning device for electronic materials that can be used as a cleaning device.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have a cleaning tank and a cleaning liquid circulation line for extracting the liquid from the cleaning tank and returning it to the cleaning tank again. In a wet cleaning apparatus for electronic materials, a deaerator is provided in a cleaning liquid circulation line to reduce the amount of gas dissolved in the cleaning liquid to a saturation degree or less at atmospheric pressure, thereby preventing generation of bubbles in the cleaning tank. It has been found that the present invention can be achieved, and the present invention has been completed based on this finding. That is, the present invention provides (1) a cleaning tank,
A wet cleaning apparatus for electronic materials, comprising: a cleaning liquid circulation line for extracting a cleaning liquid from a cleaning tank and returning the cleaning liquid to the cleaning tank again, wherein a deaerator is provided in the cleaning liquid circulation line. , Is provided. Further, as a preferred embodiment of the present invention, (2) the wet cleaning device for electronic materials according to (1), wherein the degassing device comprises a gas permeable membrane module and a decompression system.
(3) The wet cleaning apparatus for electronic materials according to (1), wherein a cleaning liquid purification device is provided in the cleaning liquid circulation line.
(4) The wet cleaning device for an electronic material according to (3), wherein the cleaning liquid purifying device is provided downstream of the deaerator.
And (5) the cleaning liquid purifying device is a filter.
The wet cleaning device for electronic materials according to the item (3) can be used.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The wet cleaning apparatus for electronic materials of the present invention has a cleaning tank, a cleaning liquid circulation line for extracting the cleaning liquid from the cleaning tank and returning the cleaning liquid to the cleaning tank again. An apparatus is provided. There is no particular limitation on the cleaning liquid used in the apparatus of the present invention. Examples of the cleaning liquid include ultrapure water in which hydrogen peroxide is dissolved, ultrapure water in which hydrochloric acid and hydrogen peroxide are dissolved, ultrapure water in which sulfuric acid and hydrogen peroxide are dissolved, and hydrofluoric acid. Examples include ultrapure water in which hydrofluoric acid and hydrogen peroxide are dissolved, ultrapure water in which ammonia and hydrogen peroxide are dissolved, and an aqueous solution of hydrofluoric acid. There is no particular limitation on the deaerator provided in the cleaning liquid circulation line of the apparatus of the present invention. For example, a decompression tank in which the gas phase is decompressed can be provided, or a gas permeable membrane module can be provided. In the gas permeable membrane module, the cleaning liquid circulating on one side of the membrane is passed, the other side of the membrane is suctioned by a vacuum pump to reduce the pressure, and the gas in the cleaning liquid is vapor-phased from the liquid phase side of the membrane. It is transmitted to the side and separated. As the deaerator, a combination of a gas permeable membrane module and a decompression system can be suitably used. It is preferable that the gas permeable membrane module has durability against chemicals contained in the cleaning liquid.

The gas permeable membrane module is preferably installed on the discharge side of the circulation pump. By reducing the pressure in the gas phase portion of the gas permeable membrane module, gas components dissolved in the chemical solution at a saturation level or higher at atmospheric pressure, for example, oxygen generated by decomposition of hydrogen peroxide can be removed. If the pressure in the gas phase is excessively reduced, the decomposition of the drug in the cleaning liquid may be promoted. If the gas in the cleaning liquid is degassed to a concentration that does not exceed the saturation at atmospheric pressure, no bubbles will be generated in the cleaning tank. It is preferable to stop. The saturation of the gas in the cleaning liquid is a value obtained by dividing the amount of gas dissolved in water by the amount of gas dissolved at atmospheric pressure and normal temperature. For example, pressure 10
Water in equilibrium with air at ⁵ Pa and a temperature of 20 ° C. dissolves 15.4 mg / liter of nitrogen and 8.8 mg / liter of oxygen and has a saturation state of 1.0 times.
By degassing, the dissolved amount of gas is 12.3 mg / liter of nitrogen,
The saturation of water with 7.0 mg / liter of oxygen is 0.8 times. By setting the degree of saturation of the gas in the cleaning liquid to about 0.8 times, the generation of bubbles in the cleaning tank can be reliably prevented. In the apparatus of the present invention, it is preferable to provide a cleaning liquid purifying device in the cleaning liquid circulation line. The cleaning liquid purifying apparatus is not particularly limited, and can be appropriately selected according to contaminants contained in the cleaning liquid. The circulating cleaning liquid is obtained by cleaning and removing contaminants attached to the object to be cleaned in the cleaning tank, and the cleaning liquid contains the contaminants.
Examples of the contaminants include fine particles, metals, and organic substances. Examples of the cleaning liquid purifying device include a filter, a filter having an ion exchange function, an ion exchanger, an organic matter decomposing device equipped with an ultraviolet irradiation device, and the like. The cleaning liquid purifying device is preferably provided downstream of the deaerator. By providing the cleaning liquid purifying device downstream of the degassing device, even if fine particles and the like are generated in the degassing device, the particles can be removed by the cleaning liquid purifying device.

FIG. 1 is a process flow diagram of one embodiment of the wet cleaning apparatus for electronic materials according to the present invention. The apparatus of the present embodiment has a batch type cleaning tank 1 and a cleaning liquid circulation line 3 for extracting a cleaning liquid from the cleaning tank with a circulation pump 2 and returning the cleaning liquid to the cleaning tank again. A cleaning liquid purifier 5 is provided. The deaerator has a vacuum pump 6 connected to a gas permeable membrane module,
A filter is used in the cleaning liquid purifying apparatus. The cleaning liquid drawn out of the batch-type cleaning tank is pumped by a circulation pump, passes through a deaerator and a cleaning liquid purifying apparatus,
It is returned to the washing tank again. Without a degassing device, trace air bubbles entrained during extraction and dissolved gas generated by the self-decomposition of cleaning liquid components such as hydrogen peroxide will be temporarily pressurized on the discharge side of the pump. Although dissolved in the cleaning liquid, after returning to the cleaning tank at atmospheric pressure, gas components exceeding the saturation level become bubbles and adhere to the surface of the object to be cleaned. By providing a deaerator in the cleaning liquid circulation line, gas components dissolved in the cleaning liquid can be reduced to a degree of saturation or less at atmospheric pressure, and generation of bubbles in the cleaning tank can be suppressed. By suppressing the generation of air bubbles, it is possible to prevent the air bubbles from adhering to the surface of the object to be cleaned and the foreign substances from collecting on the surface of the air bubbles to recontaminate the object to be cleaned.

[0008]

By using the wet cleaning apparatus for electronic materials according to the present invention, fine bubbles are not generated in the cleaning liquid in the cleaning tank, and re-contamination of the object to be cleaned and defective cleaning caused by the bubbles are prevented. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a process flow diagram of one embodiment of an electronic material wet cleaning apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Batch type cleaning tank 2 Circulation pump 3 Cleaning liquid circulation line 4 Deaerator 5 Cleaning liquid purification device 6 Vacuum pump

Claims (1)

[Claims] In a wet cleaning apparatus for an electronic material having a cleaning tank and a cleaning liquid circulation line for extracting a cleaning liquid from the cleaning tank and returning the cleaning liquid to the cleaning tank again, a deaerator is provided in the cleaning liquid circulation line. Characteristic wet cleaning equipment for electronic materials.