JP2009285549A - Filter system and evacuation method for filter system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filter system capable of improving efficiency of removing a gas and an evacuation method for the filter system. <P>SOLUTION: The filter system includes a first filter unit 20 which passes a chemical introduced from an inlet 23 through a first filter 21 to filtrate it and then discharges the chemical from an outlet 24 and a second filter unit 30 which removes a gas in the liquid before the liquid passes through the first filter 21 in the first filter unit 20. The gas-containing liquid before passing through the first filter 21 is introduced from an introduction inlet 33 into the second filter unit 30 and brought into continuous contact with the second filter 31 while passing the liquid through a gas inclusion passage 34 so as to remove the gas efficiently by the second filter 31. The liquid having passed through the passage 34 is discharged from a discharge outlet 35 to the outside of the second filter unit 30 and introduced again into the first filter unit 20. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a filter system and an exhaust method in the filter system. More specifically, for example, when filtering a chemical solution used for cleaning a semiconductor wafer or a liquid crystal substrate, for removing bubbles that may exist in the chemical solution. The present invention relates to a filter system and an exhaust method in the filter system.

  In the cleaning process of wafers in semiconductor device manufacturing, a chemical solution whose temperature is controlled by a temperature controller and from which impurities are removed by a filter device is continuously supplied to the inner tank of a cleaning tank containing several tens of wafers. The wafer is cleaned, the chemical liquid overflowing from the inner tank is received in the outer tank, and this is again circulated by the pump to the temperature controller, the filter device, and then to the inner tank. At this time, if bubbles are mixed into the cleaning liquid, the bubbles may enter the recesses on the wafer surface, and the cleaning effect will not be improved. In particular, for example, APM (SC-1) cleaning using a 1: 1: 5 to 1: 2: 7 mixed aqueous solution of ammonia, hydrogen peroxide and water under conditions such as 75 to 85 ° C., hydrochloric acid and hydrogen peroxide HPM (SC-2) cleaning using a 1: 1: 6 to 1: 2: 8 mixed aqueous solution of water at 75 to 85 ° C. or the like, or 95 to 120 for a 4: 1 mixed solution of sulfuric acid and hydrogen peroxide. In the case of SPM cleaning used under conditions such as ° C., the hydrogen peroxide solution is decomposed and oxygen is generated when the chemical solution is heated by the temperature controller, so that many bubbles are generated and introduced into the filter device.

  In order to remove the bubbles, an air vent is generally provided in the upper part of the housing of the filter device, and the gas that has risen due to buoyancy and accumulated in the upper part of the housing is manually or automatically operated. It is opened and discharged. However, manual operation of the valve is time-consuming, and automatic control of the valve generally opens and closes the valve at predetermined intervals using a timer or the like, but it is difficult to set the opening time and closing time. In some cases, expensive chemicals were leaked from the air vent.

As an exhausting method through an air vent that does not involve opening and closing of a valve, JP-A-5-103921 and JP-A-2001-121063 disclose a technique of attaching a filter that allows only gas to pass through the air vent.
JP-A-5-103921 JP 2001-121063 A

  However, in the structure in which the gas vent filter is provided in the air vent, since the gas or liquid bubbles stored in the upper part of the housing do not pass smoothly through the gas pass filter, the filter is clogged with the gas passing through the filter. A so-called air lock state was caused, and as a result, the flow of the gas or bubble-containing liquid in the vicinity of the gas passage filter stagnated, and the gas removal efficiency was poor.

  This invention is made | formed in view of the above problem, The objective is to provide the exhaust method in the filter system which can improve the exclusion efficiency of gas, and a filter system.

  In order to solve the above problems, according to the present invention, after the liquid introduced from the inlet is filtered through the first filter, the first filter area discharged from the outlet, and before the first filter passes through the first filter area. A second filter area for excluding gas in the liquid, wherein the second filter area is in contact with the liquid and allows only the gas in the liquid to pass through, and the second filter area in the first filter area. An inlet for introducing the liquid before passing through one filter into the second filter section, a gas-containing liquid passage for bringing the gas-containing liquid introduced from the inlet into contact with the second filter, and the liquid that has passed through the gas-containing passage A filter system having a discharge port for discharging the gas to the outside of the second filter section and a gas outlet for discharging the gas that has passed through the second filter to the outside of the second filter section is provided. It is.

  In the filter system according to the present invention, in parallel with the step of filtering the liquid introduced into the first filter area from the inlet (in many cases including bubbles) with the first filter and discharging from the outlet, A part is introduced from the upstream side of the first filter into the second filter section through the inlet, and the liquid is continuously brought into contact with the second filter while passing the liquid through the gas-containing passage. The contact efficiency of the second filter can be increased, and the gas in the liquid can be removed by the second filter. The liquid from which the gas has been removed (the gas may remain) is discharged from the discharge port to the outside of the second filter area. In this way, in the present invention, a bypass route having a second filter, which is different from the main route passing through the first filter, is provided, and a liquid that can contain a large amount of bubbles is created by intentionally creating a flow of liquid passing through the bypass route. The gas can be effectively removed by actively taking in the second filter area without stagnation.

  As the second filter, a pleated gas selective permeable membrane, a hollow fiber membrane or the like having a low surface energy, a hydrophobic surface that is difficult to wet, and a high air permeability and liquid impermeability can be preferably used. Typical materials include PTFE (polytetrafluoroethylene (tetrafluoroethylene)), PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer), FEP (tetrafluoroethylene / hexafluoropropylene copolymer (4.6 fluoro). ))) And the like.

  As the first filter, a known filter that can remove impurities such as particles in the liquid by filtering the liquid can be used.

  Commercially available filter units can be used as the first and second filter sections, respectively. In this case, the gas-containing liquid inlet of the second filter unit is connected to the air vent of the first filter unit, and the former to the latter. A gas-containing liquid can be fed into

  In one embodiment of the present invention, a flow path for reintroducing liquid discharged from the discharge port to the outside of the second filter section from the inlet of the first filter section to the first filter section is included. In this case, the liquid from which the gas has been removed through the second filter zone can be reintroduced into the first filter zone and used.

  According to another aspect of the present invention, the liquid introduced from the inlet is filtered through the first filter and then discharged from the outlet, and the gas in the liquid before passing through the first filter in the first filter area. And a second filter section having a second filter section that has a second filter section that can pass only gas in the liquid in contact with the liquid. Introducing the liquid before passing through the first filter in the first filter section into the second filter section and bringing it into contact with the second filter; and passing at least part of the gas in the liquid in contact with the second filter through the second filter And a step of discharging the liquid in contact with the second filter to the outside of the second filter area, and a gas having passed through the second filter to the outside of the second filter area. Exhaust process in the filter system including a degree is provided. In one embodiment of the invention, the method includes reintroducing liquid discharged outside the second filter zone from the inlet of the first filter zone into the first filter zone.

  In the filter system and the exhaust method in the filter system according to the present invention, a part of the liquid (gas-containing liquid) before passing through the first filter in the first filter section is introduced into the second filter section, and the gas-containing liquid is supplied to the second filter section. By letting it pass while contacting the filter, the contact efficiency between the gas-containing liquid and the second filter can be increased, and the gas can be efficiently excluded from the liquid.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an overall explanatory view schematically showing a chemical circulation system for cleaning a semiconductor wafer (not shown) incorporating a filter system 10 according to the present invention. The chemical solution circulation system includes an inner tank 2 in which wafers to be cleaned are accommodated in units of several tens and a cleaning tank 1 having an outer tank 3 for receiving a chemical liquid overflowed therefrom, and immediately before the chemical liquid is fed into the inner tank 2. A filter system 10 for removing impurities such as particles by filtering, in particular, a first filter unit 20 to be described later, and a chemical solution supplied to the washing tank 1 through the purification process of the filter system 10 and used for washing is again filtered. Next, a chemical solution circulation passage 4 for circulating to the cleaning tank 1, a pump 5 for circulating the chemical solution through the chemical solution circulation passage 4, and a filter system for heating the chemical solution to a predetermined temperature suitable for cleaning the wafer. 10 and a temperature controller 6 installed upstream of 10. In addition, since there exists a possibility that a foreign material may mix in the chemical | medical solution which passed through the temperature regulator 6, the temperature regulator 6 is arrange | positioned upstream of the filter system 10. FIG.

  The filter system 10 introduces a chemical solution from the upstream side of the first filter 21 in the first filter unit 20 having the first filter 21 for filtering the chemical solution, and eliminates bubbles in the chemical solution. And a second filter unit 30. The first filter unit 20 includes a cylindrical housing 22 in which the first filter 21 is accommodated, and a chemical liquid inlet provided on the bottom side of the housing 22 for introducing the chemical liquid heated by the temperature controller 6. 23, and a treatment liquid outlet 24 provided on the side of the bottom of the housing opposite to the inlet 23 for discharging the chemical solution that has passed through the first filter 21 to the outside of the housing 22, that is, the inner tank 2 side, Before passing through the filter 21, a gas-containing liquid supply port 25 provided in the upper center of the housing 22 is provided in order to supply a chemical solution that can contain bubbles to the second filter unit 30. The treatment liquid outlet 24 of the first filter unit communicates with the inner tank 2 through the circulation passage 4.

  The second filter unit 30 is provided at the center of the bottom of the housing 32, the second housing 31 that is a hydrophobic membrane that allows only gas to pass through, the cylindrical housing 32 that houses the second filter 31, and the first filter 31. Gas introduced from the inlet 33 formed around the second filter 31 in the housing 32 and the gas-containing liquid inlet 33 connected to the gas-containing liquid supply port 25 of the filter unit 20 directly or via a pipeline. A gas-containing liquid passage 34 for sufficiently contacting the second filter 31 while circulating a liquid that may contain liquid, an exhausted liquid discharge port 35 for discharging the liquid that has passed through the passage 34 to the outside of the housing 32, And an exhaust port 36 for discharging the gas that has passed through the second filter 31. The exhausted liquid discharge port 35 communicates with the outer tank 3 through the pipe line 37 in order to supply and use the liquid discharged from the temperature controller 6 and the first filter unit 20 again. However, it may be, for example, the circulation passage 4 portion immediately upstream or downstream of the pump 5. Although not shown, the gas discharged from the exhaust port 36 is appropriately processed.

  Next, the usage state of the filter system 10 will be described. The chemical liquid heated to a predetermined temperature by the temperature controller 6 is introduced into the housing 22 of the first filter unit 20 from the chemical liquid inlet 23, filtered by the first filter 21, and then from the processing liquid outlet 24 to the circulation passage 4. And is supplied to the inner tank 2 where the wafer is cleaned. The chemical solution overflowed from the inner tank 2 is received in the outer tank 3 and is recirculated from here through the circulation passage 4 to the inner tank 2 through the temperature controller 6 and then the first filter unit 20. . In this way, the chemical solution circulates through a circulation route for cleaning the wafer. At the same time, in order to remove bubbles from the chemical solution, a part of the chemical solution is passed through another circulation route as described below. .

  Bubbles are often mixed in the chemical solution introduced from the chemical solution inlet 23 into the housing 22 of the first filter unit 20, and in particular, APM (SC-1) cleaning and HPM (SC- 2) In the case of cleaning and SPM cleaning, since a chemical solution based on hydrogen peroxide is generally used at 70 ° C. or higher, oxygen is generated and bubbles are increased due to decomposition of the hydrogen peroxide. Since the bubbles in the chemical solution tend to rise to the upper portion in the housing 22 due to buoyancy, the chemical solution that may contain many bubbles in the upper portion in the housing 22 is contained in the gas in the second filter unit 30 from the gas-containing liquid supply port 25. A bypass route is provided in the filter system 10 so as to flow into the housing 32 through the liquid inlet 33 and continue to be discharged from the outlet 35 to the outside of the housing 32 through the gas-containing liquid passage 34. And darely flowing the bubble-containing liquid in the upper part of the housing 22 from the supply port 25 to the bypass route, thereby significantly reducing bubbles directed toward the first filter 21 and stagnating the liquid containing many bubbles. Instead, the gas can be removed by actively taking in the second filter unit 30. In the second filter unit 30, the chemical liquid continuously pressurizes and contacts the second filter 31 while passing through the passage 34, whereby the second filter 31 acts so as to pass only bubbles in the chemical liquid. The contact efficiency between the chemical solution and the second filter 31 is improved by setting the chemical solution circulation pressure by the pump 5 so that the bubble-containing chemical solution always flows in the passage 34 when the filter system 10 is in operation. Bubble elimination efficiency is also increased. The liquid from which the gas has been removed (the gas may not be completely removed) is sent from the outlet 35 to the outer tub 3 through the pipe 37 and recirculated.

  As described above, in this filter system, the chemical solution is circulated through the route for wafer cleaning, and at the same time, the chemical solution is circulated to another route for removing bubbles from the chemical solution, thereby reliably removing bubbles from the chemical solution. Can be used for wafer cleaning.

  In the filter system 10, the first filter 21 uses “Quick Change ATM Disposable Filter” manufactured by Nihon Entegris Co., Ltd. and the second filter 31 uses “Fluoroline P-1000 Disposable Filter” manufactured by the same company. By using the air vent as the gas-containing liquid supply port 25, it was possible to perform the chemical liquid filtration process and the chemical liquid exhaust process as expected.

It is a schematic whole figure of the chemical | medical solution circulation circuit containing the filter system of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Washing tank 2 Inner tank 3 Outer tank 4 Chemical solution circulation channel | path 5 Pump 6 Temperature controller 10 Filter system 20 1st filter unit 21 1st filter 22 Housing 23 Chemical solution inlet 24 Treatment liquid outlet 25 Gas containing liquid supply port 30 2nd filter Unit 31 Second filter 32 Housing 33 Gas-containing liquid inlet 34 Gas-containing liquid passage 35 Exhausted liquid outlet 36 Exhaust outlet

Claims (4)

A first filter section for discharging the liquid introduced from the inlet through the first filter and then discharging from the outlet;
A second filter section for eliminating gas in the liquid before passing through the first filter in the first filter section,
The second filter section is in contact with the liquid and allows only the gas in the liquid to pass therethrough, and the inlet for introducing the liquid before passing through the first filter in the first filter section into the second filter section. A gas-containing liquid passage for bringing the gas-containing liquid introduced from the introduction port into contact with the second filter, a discharge port for discharging the liquid that has passed through the gas-containing passage to the outside of the second filter section, and the second filter And a gas outlet for discharging the gas that has passed through the outside of the second filter section.   The filter system according to claim 1, further comprising a flow path for reintroducing the liquid discharged from the discharge port to the outside of the second filter section from the inlet of the first filter section to the first filter section. A first filter section that discharges the liquid introduced from the inlet through the first filter and then discharges from the outlet, and a second filter for eliminating gas in the liquid before passing through the first filter in the first filter section A venting method in a filter system comprising a zone and a second filter zone having a second filter in contact with the liquid and allowing only gas in the liquid to pass through,
Introducing the liquid before passing through the first filter in the first filter zone into the second filter zone and bringing it into contact with the second filter;
Passing at least part of the gas in the liquid in contact with the second filter through the second filter;
Discharging the liquid in contact with the second filter out of the second filter area;
And exhausting the gas that has passed through the second filter to the outside of the second filter section.   The exhaust method in a filter system according to claim 3, comprising the step of reintroducing the liquid discharged outside the second filter section from the inlet of the first filter section into the first filter section.

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