JPS6372314A - Filter - Google Patents

Abstract

PURPOSE:To provide a device which maintains a fixed effect of removing bacteria for a long period of time, by providing a cooling mechanism around a filter box. CONSTITUTION:A filter 1 has a filter box 3 which is connected with a piping 2 connecting a pure water supply source and a scrubber washing device, and installed inside a cooling tank 4. The inside of the filter box 3 is divided into a primary space 7 communicated with a piping 2 for the pure water supply source side and a secondary space 8 communicated with the scrubber washing device side. Further, a filter membrane 9, clamped with support plates 10a and 10b having a number of through-holes provided therein, is disposed in tension in the central section dividing the space 7 from 8. As a result, the primary space 7 and the secondary space 8 in the filter box 3, wherein residence of water is generated, can be maintained under fixed low temperature condition to control the growth of various bacteria, and can maintain the effect of removing bacteria of the filter membrane 9 for a long period of time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a technique that is effective when applied to a filtration device such as a filter that removes foreign substances from a liquid.
The present invention relates to a technique that is effective for use in a filtration device for supplying pure water used in the manufacture of semiconductor devices.

[Conventional technology]

Regarding pure water production technology, for example, see "Electronic Materials 1985 Separate Volume, jiHLsI Manufacturing and Testing Equipment Guidebook J P" published by Kogyo Chosukaikai Co., Ltd., November 20, 1985.
162 to P166. The outline includes a step-by-step explanation of the ultrapure water production system.

The present inventor studied a filtration technique for pure water produced and supplied as described above. Although the following is not a publicly known technique, it is a technique studied by the present inventor, and its outline is as follows.

That is, the pure water produced by the above-mentioned pure water production apparatus is supplied to, for example, a cleaning apparatus for a mask or a reticle, etc., via a predetermined pipe. At this time, since there is a possibility that foreign matter may be mixed into the pure water within the pipe, it is known to remove the foreign matter by interposing a filtration device in the middle of the pipe.

In this type of filtration device structure, a filter membrane made of long fibers or synthetic resin is stretched inside a filter box made of stainless steel alloy, etc., and the filter membrane separates the primary space from the secondary space. There is a known structure in which foreign substances such as bacteria are removed when pure water flows through the system.

Incidentally, in terms of removal efficiency, it is considered most efficient to arrange such a filtration device immediately before the device to which it is supplied.

[Problem that the invention seeks to solve]

However, depending on the location of the above filtration device,
In many cases, the environment is high temperature, such as near the power supply or motor of the destination device.

When a filtration device is used in such a high-temperature environment, bacteria generated inside the filter box of the filtration device tend to grow, and some of these bacteria pass through the filter membrane and are supplied to the secondary space. The filtration efficiency may be significantly reduced by contaminating the purified water or clogging the filter membrane.

In other words, if the temperature inside the filter of the filtration device is such that bacteria can easily grow, the filter itself will not be able to maintain its inherent sterilizing effect for a specified period of time, making it necessary to replace the filter frequently. The inventor has discovered that it becomes necessary to do so.

The present invention has been made focusing on the above problems,
The purpose is to provide a filtration technique that can maintain a predetermined sterilization effect over a long period of time.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means for solving problems]

A brief overview of typical inventions disclosed in this application is as follows.

That is, a cooling mechanism is provided around a filter box that performs the filtration action of the filtration device.

[Effect]

According to the above-mentioned means, each of the primary and secondary spaces in the filter box where water accumulates can be maintained at a predetermined low temperature condition, so the growth of bacteria can be suppressed and the filter membrane can be sterilized over a long period of time. The effect can be maintained.

〔Example〕

FIG. 1 is an explanatory diagram showing a filtration device that is an embodiment of the present invention.

The filtration device 1 of this embodiment is a so-called scrubber cleaning device that cleans masks for manufacturing semiconductor devices! This is a filtration device for supplying water such as pure water to a vessel (not shown), and is used by being interposed in the middle of the piping 2 between the pure water supply source and the scrubber cleaning device.

The filtration device 2 has a structure in which a filter box 3 connected to the piping 2 is provided inside a cooling tank 4, and the cooling tank 4 is filled with cooling water 5. The cooling water 5 has a structure in which it is sequentially circulated to and from the cooling tank 4 by a circulation type low-temperature constant temperature device 6 disposed near the cooling tank 4.
The inside is always maintained at a predetermined low temperature condition.

In this embodiment, the temperature inside the cooling tank 4 is controlled by a low-temperature constant temperature device 6 to maintain a temperature condition of 1 to 7° C., for example.

Inside the filter box 3 is a pipe 2 on the pure water supply source side.
It is separated into a primary space 7 that communicates with the scrubber cleaning device, and a secondary space 8 that communicates with the scrubber cleaning device side. A support plate 10a made of a stainless steel alloy with a filter membrane 9 and a large number of through holes is provided in the central portion separating these spaces 7 and 8.

10b and is stretched in a state of being sandwiched between them.

Here, the filter membrane 9 used in this embodiment is, for example, a cellulose ester-based so-called membrane filter, in which cellulose ester is dissolved in a mixed solvent such as alcohol, water, acetone, etc., and then it is cast to a thickness of, for example, It is obtained by processing it into a film shape of about 150 μm.

Note that, as the filter membrane 9, a so-called depth filter obtained by compressing a long fiber material such as cellulose fiber to a predetermined thickness may also be used.

These filter membranes 9 have a structure in which a large number of pores, for example, pores of about 1 μm, penetrate through the front and back surfaces of the membrane, and water, for example, flows from the secondary space 7 side to the secondary space 8 side. When the pure water 11 flows, foreign particles are captured on the surface of the filter membrane 9 on the primary space 7 side or inside the filter membrane 9. Therefore, when the water, for example, the pure water 11, passes through the filter membrane 9, foreign particles therein are captured, and the water becomes a predetermined purity and flows out to the secondary space 8 side.

By the way, in such a filtration technique using the filter membrane 9, bacteria grow from the foreign particles captured by the filter membrane 9, and the growth of these bacteria may be further accelerated by the high temperature environment inside the filter box 3. . If the amount of bacteria in the secondary space 7 increases in this way, the filtration efficiency of the filter membrane 9 will decrease relatively, the filter membrane 9 will become clogged, and the bacteria will be transferred to the secondary space 8 side. This will result in an outflow of water. As described above, under high temperature conditions, the original filtration efficiency of the filter membrane 9 cannot be maintained for a predetermined period of time, and the pure water 11 flowing out to the secondary space 8 side may become contaminated.

However, according to this embodiment, the filter box 3 is immersed in a cooling tank 4 in which cooling water 5 is circulated, and the temperature conditions in the primary space 7 and secondary space 8 in the filter box 3 are 1°C. The temperature is maintained at around 7°C. Since the growth of germs is suppressed under such low temperature conditions, the original filtration efficiency of the filter membrane 9 can be maintained for a long period of time.

As described above, according to this embodiment, the following effects can be obtained.

(1) Since the filter box 3 covered with the filter membrane 9 is immersed in the cooling water 5 in the cooling tank 4 and maintained at a predetermined low temperature, the growth of various bacteria inside the filter box 3 is suppressed. Therefore, the sterilizing effect of the filter membrane 9 can be maintained for a long period of time.

(2) According to (1) above, the degree of exchange of the filter membrane 9 can be reduced, so that it is possible to supply pure water 11 of standard purity at low cost.

(3) By using the cooling mechanism as a structure in which the cooling water 5 is circulated within the cooling tank 4, the growth of various bacteria within the filter box 3 can be suppressed by providing a slight additional mechanism to the conventional filtration mechanism. . .

(4) The above (1) to (3) enable highly reliable pure water treatment.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor. For example, as a cooling mechanism, a case has been described in which the filter box 3 is immersed in a cooling tank 4 in which cooling water 5 is circulated, but the invention is not limited to this. Any cooling mechanism may be used, such as a piped structure.

The above explanation has mainly been about the case where the invention made by the present inventor is applied to the field of application, which is a filtration device for supplying pure water in the manufacture of semiconductor devices.
The present invention is not limited thereto, and can be applied to, for example, filtration devices used for water supply in the pharmaceutical, medical, and other fields.

〔Effect of the invention〕

A brief explanation of the effects obtained by typical inventions disclosed in this application is as follows.

That is, it has a filter box that is interposed in the middle of the liquid distribution piping, communicates with each distribution piping, and is separated from the outside by a filter membrane into a primary space and a secondary space. By adopting a filtration device structure in which a cooling mechanism is provided around the box to cool each of the above spaces, it is possible to maintain each of the primary and secondary spaces within the filter box, where water accumulates, at a predetermined low temperature condition. Therefore, the growth of various bacteria can be suppressed, and the sterilization effect of the filter membrane can be maintained for a long period of time.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a filtration device that is an embodiment of the present invention. 1... Filter device, 2... Piping, 3... Filter box, 4... Cooling tank, 5... Cooling water, 6...
Low-temperature constant temperature device, 7...-main space, 8... secondary space,
9... Filter membrane, 10a, lQb... Support plate,
11...Water, for example pure water. Im, 7th σb depth/I and 9

Claims (1)

[Claims] 1. It has a filter box that is interposed in the middle of the liquid distribution piping, communicates with each distribution piping, and is separated into a primary space and a secondary space by a filter membrane. A filtration device characterized in that a cooling mechanism for cooling each of the spaces is provided around the filter box. 2. The filtration device according to claim 1, wherein the liquid flowing through the circulation pipe is water.