JP2001252518A - Chemical filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide chemical filter capable of simply evaluating/estimating the life of the filter. SOLUTION: The chemical filter has a parallel flow type filter 1, wherein gas adsorbable filter media are arranged in many rows in parallel to an air passing direction, as a principal part and a local low pressure loss part (2) is provided in pressure loss distribution within the plane crossing the air passing direction of the parallel flow type filter 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemical filter, and more particularly, to a chemical filter that facilitates determination and prediction of filter life.

[0002]

2. Description of the Related Art In the manufacture of semiconductors, the presence of gaseous contaminants such as ammonia in the atmosphere causes pattern defects on wafers and dielectric breakdown. Therefore, in a semiconductor manufacturing plant, manufacturing is performed in a clean room in which gaseous pollutants are reduced to an extremely low concentration of ppb level, and the air in the clean room is forcibly circulated while removing harmful gases using a chemical filter. Like that.

However, the performance of removing gaseous pollutants by a chemical filter gradually decreases over time.
Every time the filter removal efficiency drops to a certain level, it is necessary to replace the filter with a new one. For this reason, conventionally, a method of predicting the replacement time by knowing the filter life in advance has been adopted. For example, by forcibly supplying a pollutant gas having a concentration of several tens to several thousand times the concentration in a normal clean room to a target filter, a life expectancy when air having a normal concentration is supplied has been performed. Was. But,
With this method, it is difficult to accurately predict the life, and it has not been possible to derive an optimum replacement time.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and to easily determine the filter life.
It is to provide a chemical filter that can be predicted.

[0005]

A chemical filter according to the present invention, which achieves the above object, comprises a parallel flow type filter in which gas adsorbing filter media are arranged in multiple rows in parallel with the air passage direction. A local low pressure loss portion is provided in a pressure loss distribution in a plane intersecting the air passage direction of the filter.

In general, a parallel flow type filter is designed to remove gaseous pollutants by adsorbing air on the surface of the filter medium while flowing air in parallel to the surface of the filter medium. Has the property of speeding up.
Since the local low pressure loss portion in the present invention has a larger air flow rate per unit cross-sectional area than other portions, the filter life is quickly reached. Therefore, by monitoring the removal efficiency of gaseous pollutants in the low pressure loss part, the life of the filter body can be easily determined and predicted from the life of the low pressure loss part.

[0007]

FIG. 1 is a schematic diagram showing a chemical filter according to an embodiment of the present invention in a disassembled state for each component. This chemical filter is provided, for example, at an air supply port to a clean room, and removes gaseous pollutants contained in air.

In FIG. 1, reference numeral 1 denotes a parallel flow type filter which is a main part of a chemical filter, and ventilation filters 2 and 3 are disposed before and after the filter, and a filter unit 4 is formed by integrally laminating the filters. It has been incorporated into. Although the fixing means is not shown in the figure, any known means such as, for example, providing a protective wire mesh on both outer sides of the ventilation filters 2 and 3 can be used.

The parallel flow type filter 1 is separated into a main body 1a and a section 1b, and the section 1b is removably combined with the main body 1a. In this parallel flow type filter 1, as shown in FIG. 2, a flat gas-adsorbing filter medium 10 and a corrugated gas-adsorbing filter medium 11 are alternately laminated and adhered to each other. It is configured to form parallel multi-row channels.

The gas adsorbing filter media 10 and 11 are not particularly limited as long as they have a gas adsorbing function, and any of known materials can be used. For example, there may be mentioned those obtained by carrying activated carbon on paper made from pulp and / or synthetic fibers, those carrying ion-exchange fibers or resins, and those carrying zeolite.

The ventilation type filter 2 placed in front of the parallel flow type filter 1 is provided with a notch 2a at a position facing the section 1b. The pressure loss of the air passing from the notch 2a to the section 1b is lower than the pressure loss of the air passing from the ventilation filter 2 to the body 1a. As a means for giving such a pressure loss difference, a similar notch may be provided in the ventilation type filter 3 on the rear side. Alternatively, instead of providing the cutout, the weight (filter density) of the same location may be reduced to reduce the pressure loss.

Each of the air-permeable filters 2 and 3 is made of a dust-removing filter material, and is arranged so as to intersect, and more preferably, to intersect, the air passage direction. As the dust-removing filter material constituting the ventilation type filter, a nonwoven fabric in which long fibers or short fibers of synthetic fibers are randomly arranged and bonded is preferably used. Alternatively, a knitted fabric using synthetic fibers or natural fibers may be used.

The guide tube 6 is provided at the rear of the portion corresponding to the section 1b of the filter unit 4 incorporated in the frame 5 as described above. The air that has passed through the main body 1a of the parallel flow filter 1 from the ventilation filter 2 is supplied to the clean room, whereas the air that has passed through the cutout 2b from the notch 2a is guided by the guide pipe 6 to the system outside the clean room. It is designed to be discharged outside. This guide tube 6
Although it is not always necessary, if the guide tube 6 is provided, the atmosphere of the clean room can be maintained more clean.

The above-described chemical filter of the present invention is set, for example, in an air supply port of a clean room, and changes over time in the removal efficiency of gaseous pollutants in the main body 1a and the section 1b of the parallel flow filter 1 are observed. Then, it becomes as shown in FIG.

That is, the air passing through the main body 1a is:
Since a high pressure loss is received due to the flow resistance of the ventilation type filter 2, the flow rate per unit cross-sectional area is smaller than that of the air passing through the section 1b. Therefore, in view of the efficiency of removing gaseous pollutants, the performance of the section 1b having a large air flow rate decreases rapidly as shown by the curve B in the graph of FIG. The main body 1a can maintain high performance as indicated by the curve A for a long time.

Therefore, by periodically monitoring the removal efficiency of the section 1b, it is possible to efficiently determine and predict the time for replacing the filter. For example, section 1b
If the filter is replaced at the point in time t _{1 at} which the performance has decreased to 80% of the initial performance, the clean ream can be constantly maintained at a constant cleanliness, and the filter can be used to the performance limit without waste. Therefore, utilization efficiency can be improved.

In addition, regular monitoring can be facilitated by making the section 1b detachable.

The above-described chemical filter of the present invention can be suitably applied not only to a space where cleanliness is required, such as a clean room or a clean bench, but also to a resist coating apparatus or a resist installed in a clean room. By installing the apparatus in a semiconductor manufacturing apparatus such as a developing apparatus, an exposure apparatus (scanner), and a film forming apparatus, the concentration of contaminated gas in the air in these apparatuses can be further reduced.

[0019]

As described above, according to the chemical filter of the present invention, a local low pressure loss portion is provided in the pressure loss distribution in a plane intersecting the air passage direction of the parallel flow type filter. By monitoring the removal efficiency of gaseous pollutants in the low pressure loss part, the life of the filter body can be easily determined and predicted from the life of the low pressure loss part.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a chemical filter according to an embodiment of the present invention in a disassembled state for each component.

FIG. 2 is an enlarged perspective view showing a main part of a parallel flow type filter used in the present invention.

FIG. 3 is a graph showing the relationship between the removal efficiency of gaseous pollutants and the elapsed time between the main body and the section of the parallel flow filter used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Parallel flow type filter 1a Main body part 1b Section part 2, 3 Ventilation type filter 2a Notch part 4 Filter unit 5 Frame 6 Guide tube

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D012 CA09 CA10 CB02 CE02 CF05 CF10 CG03 CH01 CK10 4D058 JA12 JB24 JB25 SA04 TA02 UA13 UA30

Claims (5)

[Claims] A main part is a parallel flow type filter in which gas adsorbing filter media are arranged in multiple rows in parallel with the air passage direction, and a local pressure loss distribution in a plane intersecting the air flow direction of the parallel flow type filter. Chemical filter with a typical low pressure loss part. 2. A ventilation filter in which a dust-removing filter medium is disposed so as to intersect with an air passage direction at at least one of an air inlet and an air outlet of the parallel flow filter. The chemical filter according to claim 1, wherein the low pressure loss portion is formed by providing a ventilation resistance portion. 3. The chemical filter according to claim 1, wherein a guide path for discharging the passing air out of the system is provided downstream of the low pressure loss portion of the parallel flow type filter. 4. The chemical filter according to claim 1, wherein a portion corresponding to said low pressure loss portion of said parallel flow type filter is detachably detachable. 5. A clean room or semiconductor manufacturing apparatus comprising the chemical filter according to claim 1.