JPH1176719A - Air cleaning filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air cleaning filter which excels in disaster prevention and does not cause lowering of humidity and can be used in a space of high purity in which substrates or the like can be prevented from being contaminated by organic matter. SOLUTION: In an air cleaning filter 11, adjacent to a first filter part 11a provided with synthetic zeolite and having air permeability on the upstream side or the downstream side thereof, a second filter part 11b having property of adsorbing gaseous organic impurities and provided with inorganic adsorbent having effective fine pore diameter larger than that of the synthetic zeolite and having air permeability is arranged. The effective fine diameter of the synthetic zeolite is not less than 7 Å, and in the inorganic adsorbent of the second filter part 11b, it is preferable that the total volume of fine pores distributing in the range of 15-300 Å is not less than 0.2 cc/g or that the specific surface area of the inorganic adsorbent is not less than 100 m<2> /g.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device (L
TECHNICAL FIELD The present invention relates to an air purification filter having a function of removing gaseous organic impurities in an air atmosphere, which cause deterioration in quality during the production of SI) and a liquid crystal display (LCD).

[0002]

2. Description of the Related Art Today, cleaning devices are widely used for manufacturing semiconductors, LCD panels, and the like. For example, a semiconductor manufacturing line from a bare wafer to the manufacture of 1MDRAM chips includes about 200 steps, and an LCD panel manufacturing line from elementary glass to a 9.4-type TFT includes about 80 steps. I have. In these production lines, it is difficult to always continuously flow a wafer or a glass substrate through each process. For example, in a TFT-LCD manufacturing line, a semi-finished substrate on which a single circuit is formed in a previous process takes several hours to several tens of hours in a transfer container (carrier) or a storage (transfer) before being transferred to a subsequent process. Inside the stocker), it stands by while exposing it to the atmosphere of the cleaning device.

As described above, when a semiconductor substrate or an LCD substrate is left in a normal cleaning device atmosphere for a long time, organic substances derived from the cleaning device atmosphere adhere to their surfaces. When an organic substance adheres to a silicon wafer as a semiconductor substrate, the following inconvenience occurs. That is, an insulating oxide film (SiO ₂ ) is formed on the wafer surface with the organic substance attached.
When carbon is formed, the carbon component in the organic matter becomes an insulating oxide film (Si
By being taken into O ₂ ), the withstand voltage of the insulating oxide film is greatly reduced, and the leak current is greatly increased. In addition, the adhesion of the organic substance to the surface of the silicon wafer deteriorates the adhesiveness of the resist film, which may cause exposure and etching defects, thereby making it impossible to form an accurate pattern. In addition, the surface resistivity of the wafer is increased, and the wafer is likely to be charged, and the fine particles floating in the air are easily electrostatically attracted to the wafer surface, so that the dielectric breakdown is more likely to occur. Further, the organic impurities contained in the atmosphere of the cleaning apparatus cause the optical lenses and mirrors of the exposure apparatus and the like to have low optical efficiency due to fogging. This is a so-called photo-CVD reaction in which organic impurities contained in the atmosphere of the cleaning device cause a photochemical reaction by the ultraviolet rays of the optical equipment, and the products adhere to the surface. In the case where amorphous silicon (a-Si) for a thin film transistor (TFT) is formed on the surface of a glass substrate which is an LCD substrate while organic substances derived from the atmosphere adhere to the glass substrate, the glass substrate and the a-Si film are formed. Poor adhesion results. As described above, the organic matter derived from the atmosphere of the cleaning device is a semiconductor element or L
Affects CD manufacturing.

On the other hand, organic substances adhering to the surface of the substrate can be removed by a cleaning technique such as ultraviolet / ozone cleaning. However, the cleaning time per substrate requires several minutes, and frequent cleaning lowers productivity. As described above, particularly in recent years, in addition to the contamination of the substrate by metal impurities and particles, the influence of organic impurities present in the atmosphere of the cleaning apparatus on semiconductor production has been regarded as a problem. For example, US SEMATECH is 19
Technology T announced on May 31, 1995
transfer # 95052812A-TR "For
ecast of Airborne Molecul
ar Containment Limits f
or the 0.25 Micron High P
performance Logic Process "
Table 1 shows the control level of organic contamination on the wafer surface (the allowable value of surface contamination) as shown in Table 1. According to the description, 5 × 10 ¹³ carbon atoms in the previous step in 1998 number / cm ^2, 1 × 10 ¹⁵ carbon atoms number in a subsequent step / cm ²
Control is needed.

[0005]

[Table 1]

[0006] Conventionally, as an apparatus for removing gaseous organic impurities contained in the atmosphere of a cleaning apparatus, a chemical filter for adsorbing and removing gaseous organic impurities using activated carbon has been used. As a simplest form of a chemical filter using activated carbon, a filling cylinder having a configuration in which granular activated carbon is packed in a predetermined case or the like is known. In addition, as other types, a chemical filter composed of fibrous activated carbon and a felt-shaped composite compounded with an organic binder of low-melting polyester or polyester non-woven fabric, or granular activated carbon is firmly attached to urethane foam or non-woven fabric with an adhesive. Block-shaped and sheet-shaped chemical filters are also known.

[0007]

For example, in the case of a clean room in which the ceiling surface is a surface from which clean air is blown out, a chemical filter is arranged upstream of the particle removal filter mounted on the ceiling. But,
This is an extremely effective means for removing gaseous organic impurities in the air atmosphere of a clean room. However, activated carbon is a flammable substance specified by the Fire Service Act, and strict attention must be paid to fire. Therefore, from the viewpoint of disaster prevention,
Chemical filters using activated carbon are difficult to place on the ceiling.

[0008] A cleaning apparatus used for manufacturing LSIs and LCDs usually has a temperature of 23 to 25 ° C and a relative humidity (45 ° C).
± 10)% atmosphere is maintained. However, since activated carbon is weakly hydrophobic, it absorbs not only gaseous organic impurities but also moisture in the air. In addition, activated carbon rapidly increases the amount of water adsorbed in the air when the relative humidity increases only slightly. For example, unused activated carbon that has almost no water adsorption is stored in a container with a dry atmosphere inside, and the activated carbon is suddenly exposed to a clean room atmosphere at a temperature of 23 to 25 ° C. and a relative humidity of 50%. Until saturation is reached, a large amount of moisture in the air will be adsorbed. Therefore, if a chemical filter impregnated with unused activated carbon is attached to the air supply side to the cleaning device, the activated carbon used in the chemical filter can be adjusted even if the relative humidity is adjusted to a predetermined value upstream of the chemical filter. Absorbs a large amount of moisture in the air, so that the relative humidity in the cleaning device becomes lower than a predetermined value. The decrease in humidity facilitates the generation of static electricity and hinders the manufacture of LSIs and LCDs. In order to solve this problem, the manufacturer of the chemical filter impregnated with activated carbon must investigate the temperature and humidity of the clean room atmosphere of the customer to whom this chemical filter is shipped before shipping, and determine the water content that matches the temperature and humidity. It is necessary to perform the troublesome work of intentionally adsorbing the activated carbon in the chemical filter and shipping it in a sealed package.

The conventional chemical filter of the filling cylinder type has a high adsorbing efficiency for organic substances, but has a drawback of high pressure loss (ventilation resistance). On the other hand, the conventional chemical filter in the form of a felt or sheet has excellent air permeability, and the adsorption efficiency is not so inferior to that of the filled cylinder. However, many of them were originally developed to remove harmful gases and odors in the living environment, and were directly used as chemical filters. Since its performance specifications are adapted to the field of living environment, it is used as an air purification filter to remove trace amounts of gaseous organic impurities that cause substrate surface contamination when manufacturing semiconductor devices (LSI) and liquid crystal displays (LCD). There was no performance specification to use. That is,
Filter material (for example, non-woven fabric, organic binder, etc.), adhesive (for example, neoprene-based resin, urethane-based resin, epoxy-based resin, silicon-based resin, etc.) that attaches activated carbon to the sheet, and filter media to the surrounding frame Gaseous organic impurities generated from a sealing material (for example, neoprene rubber, silicon rubber, or the like) used for fixing may be included in air after passing through the chemical filter, which may adversely affect semiconductor manufacturing. Further, these felt-shaped and sheet-shaped chemical filters remove gaseous organic impurities generated from the chemical filter itself again in the passing air while removing trace organic impurities of the order of ppb contained in the clean room atmosphere. Mixed in.

Japanese Patent Application Laid-Open No. 61-1 is a filter which can be used as a chemical filter for preventing contamination of the substrate surface of this kind.
No. 03518 and JP-A-3-98611. The former is a filter that was developed for removing odors and is a filter that is made by impregnating an aqueous solution containing powdered activated carbon, an emulsion-type adhesive, and a solid acid into a base material made of urethane foam and then drying it. From rubber latex and other water-dispersed organic adhesives,
Further, desorption of gaseous organic substances also occurs from urethane foam itself as a base material. The latter is developed for the removal of harmful gases and odors that cause health hazards, and requires the use of an organic binder in combination with the adsorbent. Polyethylene and other organic substances are shown as this organic binder, and the Desorption of gaseous organic matter is inevitable.

Accordingly, an object of the present invention is to provide an air purification filter which is excellent in disaster prevention, does not cause a decrease in humidity, and can be used in a highly purified space which can prevent organic contamination of a substrate or the like.

[0012]

In order to solve the above-mentioned problems, according to the first aspect of the present invention, a filter is provided adjacent to an upstream or downstream side of a gas-permeable first filter section provided with a synthetic zeolite. And a gas-permeable organic impurity, and a gas permeable second filter portion having an inorganic adsorbent having an effective pore diameter larger than the effective pore diameter of the synthetic zeolite. An air purifying filter is provided. The air purifying filter of the first aspect is excellent in disaster prevention because it does not use activated carbon which is a combustible material. According to the air purification filter of the present invention, it is possible to remove gaseous organic impurities in the air circulating in the advanced cleaning device without lowering the humidity.

According to the first aspect of the present invention, as described in the second aspect, the first filter section has a structure in which synthetic zeolite is fixed to a surface of a support, and the second filter section has However, a configuration in which the inorganic adsorbent is fixed to the surface of the support may be employed. In this case, for example, as described in claim 3, the first filter section impregnates the support with a suspension in which the synthetic zeolite is dispersed, and then dries the synthetic zeolite on the support surface. Wherein the second filter section impregnates the support with a suspension in which the inorganic adsorbent is dispersed, and then dries the support so that the inorganic adsorbent is fixed on the support surface. It is.

According to a fourth aspect of the present invention, the first filter section has a structure in which pellets made of synthetic zeolite powder are fixed to a support, and the second filter section has A configuration in which pellets formed of an inorganic adsorbent powder are fixed to a support may be used.

Further, as described in claim 5, the support having air permeability is divided into two regions at a boundary surface intersecting the direction of air flow of the support, and the support is provided in one region. The first filter part is formed by fixing a pellet formed of synthetic zeolite or a powder of synthetic zeolite on the surface of the above, and the pellet formed of the inorganic adsorbent or the powder of the inorganic adsorbent on the surface of the support in the other region. It is also possible to adopt a configuration in which the second filter portion is formed by being fixed.

According to a sixth aspect of the present invention, when the synthetic zeolite or the pellet formed of the synthetic zeolite powder is fixed to the surface of the support, and / or the inorganic adsorbent or the inorganic adsorbent is adhered to the surface of the support. In fixing the pellets formed of the powder of the inorganic adsorbent, it is preferable to use a fixing aid comprising at least one of talc, kaolin mineral, bentonite, sodium silicate, silica and alumina.

[0017] As described in claim 7, the inorganic adsorbent of the second filter portion is, for example, diatomaceous earth, silica, or the like.
It may be composed of at least one of alumina, a mixture of silica and alumina, aluminum silicate, activated alumina, porous glass, hydrous magnesium silicate clay mineral having a ribbon-like structure, activated clay, and activated bentonite.

Further, as set forth in claim 8, the synthetic zeolite has an effective pore diameter of 7 Å or more, and is distributed in the range of 15 to 300 Å in the inorganic adsorbent of the second filter portion. Whether the total volume of the pores is 0.2 cc / g or more per weight,
Alternatively, the specific surface area of the pores of the inorganic adsorbent may be 100 m ² / g or more.

[0019] As described in claim 9, the support can be a honeycomb structure. In this case, it is preferable that the honeycomb structure is a structure including inorganic fibers as an essential component.
In the present specification, the honeycomb structure may have a so-called honeycomb structure, or may have a lattice-like or corrugated cross-section and allow air to pass through cells serving as elements of the structure. In the present invention, the support is not limited to the honeycomb structure. A three-dimensional network structure such as rock wool can also be suitably used as a support. In this case, as described later, the synthetic zeolite or the inorganic adsorbent, which is the adsorbent of the present invention, is fixed not only in the plane direction of the network structure but also in the depth direction.

Further, as set forth in claim 11, the first filter section is formed by filling the pellets of the synthetic zeolite in a casing, and the pellets of the inorganic adsorbent are charged in another casing. Thus, the second filter unit may be configured.

Furthermore, as described in claim 12, the synthetic zeolite is preferably water-repellent.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an air purification filter according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a perspective view of an air purification filter 11 according to an embodiment of the present invention, and (a) and (b) show an exploded view and an assembled view, respectively. As shown in FIG. 1A, the air purification filter 11 includes a first filter section 11a containing synthetic zeolite for removing gaseous organic impurities in passing air, and a first filter section 1a.
A second filter part 11b having an air permeability and an inorganic adsorbent having an effective pore diameter larger than the effective pore diameter of the synthetic zeolite for removing gaseous organic impurities which cannot be removed by the synthetic zeolite 1a. ing. As shown in FIG. 1B, these first filter units 11a
The second filter portion 11b and the second filter portion 11b are overlapped so as to be adjacent to each other, and the two members are connected to each other by screwing the flange 34 with a fluororesin-based packing 39 that generates less gaseous organic impurities therebetween. On the upstream side and the downstream side of the air purification filter 11 connected in this way, connection flanges 20 to ducts (not shown) are formed. In addition,
Each of the first and second filter portions 11a and 11b is made of only a material containing no combustible material, and is made of only a material that does not generate gaseous organic matter.

FIG. 2 shows the first and second filter sections 11.
It is a schematic exploded view of a and 11b. Each of the first and second filter units 11a and 11b has the same configuration,
The entire surface of a honeycomb structure 32 having a configuration in which a thin sheet 31 having no unevenness is sandwiched between adjacent corrugated sheets 30 is
In the first filter section 11a, synthetic zeolite is fixed, and in the second filter section 11b, an inorganic adsorbent having an effective pore diameter larger than that of the synthetic zeolite is fixed. As described later, the effective pore size of the synthetic zeolite is preferably 7 Å or more. As described later, the inorganic adsorbent includes diatomaceous earth, silica, alumina, a mixture of silica and alumina, aluminum silicate, activated alumina, porous glass, hydrated magnesium silicate clay mineral having a ribbon-like structure, activated clay,
It is preferred that it be made of at least one kind of activated bentonite. Table 2 shows the pore properties of these inorganic adsorbents for reference.

[0025]

[Table 2]

As shown in FIG. 2, both of the first and second filter sections 11a and 11b are provided in the flow direction of the processing air (FIG. 2).
The outer frames 35a, 35b, 35c, and 35d made of aluminum are assembled in a cylindrical shape so as to open in the direction indicated by the hollow arrow 33 in the middle, and the honeycomb structure 32 is disposed in the internal space. . In the first filter portion 11a, synthetic zeolite is fixed on the surface of the honeycomb structure 32, and in the second filter portion 11b, the effective fine particle larger than the effective pore diameter of the synthetic zeolite is fixed on the surface of the honeycomb structure 32. The structure is such that an inorganic adsorbent having a pore diameter is fixed.

The external shape and dimensions of the air purification filter 11 can be arbitrarily changed according to the installation space. In addition, the first filter unit 11 containing synthetic zeolite
a and the second filter portion 11b containing the inorganic adsorbent described above.
May be arranged on the upstream side with respect to the ventilation direction of the air purification filter 11.

Here, the first and second filter units 11a, 1
An example of the manufacturing method 1b will be briefly described. Inorganic fiber (ceramic fiber, glass fiber, silica fiber, alumina fiber, etc.), organic material (mixture of pulp and molten vinylon) and calcium silicate are blended at 1: 1: 1 equivalent weight, wet papermaking method To a paper thickness of about 0.3 mm.
Instead of calcium silicate, a clay mineral such as sepiolite or attapulgite mainly containing magnesium silicate may be used. The papermaking sheet is corrugated by a corrugator, and the completed corrugated sheet 30 is bonded to a thin sheet 31 with an adhesive to form a honeycomb structure 32 as shown in FIG. This honeycomb structure 32
Is placed in an electric furnace and subjected to a heat treatment at 400 ° C. for one hour to remove all organic components, thereby making the honeycomb structure 32 porous. Next, in the first filter portion 11a, the synthetic zeolite powder (several μm) and an inorganic binder (silica sol, alumina sol, sodium silicate, etc.) are dispersed, and in the second filter portion 11b, the synthetic zeolite is dispersed. Inorganic adsorbents having an effective pore size larger than that of zeolite (diatomaceous earth, silica, alumina, a mixture of silica and alumina, aluminum silicate, activated alumina, porous glass, hydrated magnesium silicate clay with a ribbon-like structure Powder (several μm) of mineral, activated clay, and activated bentonite) and inorganic binder (silica sol,
Alumina sol, sodium silicate, etc.)
After immersing the porous honeycomb structure 32 for several minutes,
The first and second filter portions 11a and 11b can be obtained by drying by a heat treatment at 1 ° C. for one hour. However,
Silica sol and alumina sol are suspensions containing monodispersed nanometers to tens of nanometers of primary particles. When they are fixed on the surface of the support and dried, silica gel, which is a three-dimensional aggregate of primary particles aggregated, Changes to alumina gel. Therefore, even if the porous honeycomb structure 32 is immersed in a suspension of only an inorganic binder of silica sol or alumina sol and then dried, the second filter portion 11 in which silica gel or alumina gel is fixed to the surface of the honeycomb structure 32 is formed.
b can be obtained.

The first and second filter sections 11a, 11a
The air purifying filter 11 constituted by b does not contain any combustible materials in the constituent material, and removes all gaseous organic impurity components which cause surface contamination and contained in the constituent material when the air purifying filter is heat-treated. Since they are separated and removed, no gaseous organic impurities are generated from the air purification filter itself.

FIG. 3 shows the first and second filter sections 11.
FIG. 5 is a schematic exploded view of the air purification filter 11 for showing another connection state of the air purifying filter 11a and 11b. The air purifying filter 11 shown in FIG. 3 has an aluminum outer frame 35a, 35b, 35c, 3 longer than that described in FIG.
5d is assembled in a cylindrical shape, and a honeycomb structure 32a in which synthetic zeolite is fixed on the surface and an inorganic adsorbent having an effective pore diameter larger than the effective pore diameter of the synthetic zeolite are fixed in the inner space. It is constituted by arranging both of the bodies 32b. In this case, the honeycomb structures 32a and 32b may be arranged in close contact with each other, or the honeycomb structures 32a and 32b may share a common tubular aluminum outer frame 35a, 35b, 35c, 3
In the 5d internal space, they may be arranged apart from each other. In FIG. 3, the first filter portion 11a is formed by the honeycomb structure 32a and the outer frames 35a to 35d, and the second filter portion 11b is formed by the honeycomb structure 32b and the outer frames 35a to 35d.

FIG. 4 is a perspective view showing the structure of an air purification filter 11 according to another embodiment. In this embodiment, a honeycomb structure 80 as a support having air permeability is used.
Is divided into two regions on the boundary surface intersecting with the ventilation direction 83, and the honeycomb structure 8 is divided into one region in one region.
The first filter portion is formed by fixing a pellet formed of synthetic zeolite or a powder of synthetic zeolite on the surface of the honeycomb structure 80, and the surface of the honeycomb structure 80 is formed of an inorganic adsorbent or a powder of an inorganic adsorbent on the other region. The second pellets are formed by fixing the pellets thus formed. In this embodiment, approximately half of the upstream side 81 of the undivided integrated honeycomb structure 80 with respect to the ventilation direction 83 is impregnated with a suspension in which the synthetic zeolite is dispersed, and then dried to form a honeycomb structure. An inorganic material layer of synthetic zeolite is formed on the surface of the upstream side 81 of the body 80, and the remaining half of the downstream side 82 with respect to the ventilation direction 83 of the honeycomb structure 80 is used for an effective fine pore larger than the effective pore diameter of the synthetic zeolite. Inorganic adsorbent having pore size (at least one of diatomaceous earth, silica, alumina, mixture of silica and alumina, aluminum silicate, activated alumina, porous glass, hydrous magnesium silicate clay mineral having a ribbon-like structure, activated clay, activated bentonite Of the inorganic adsorbent on the surface of the downstream side 82 after being impregnated with the suspension in which the inorganic adsorbent is dispersed. It is obtained by forming a. The inorganic material layer of the synthetic zeolite and the inorganic material layer of the inorganic adsorbent may overlap each other near the boundary between the upstream side 81 and the downstream side 82, or near the boundary between the upstream side 81 and the downstream side 82,
The original base of the honeycomb structure 80 on which neither the inorganic material layer of the synthetic zeolite nor the inorganic material layer of the inorganic adsorbent is formed may be exposed. As shown in FIG. 3, if this honeycomb structure 80 is surrounded by a cylindrical aluminum outer frame, the air purification filter 11 according to the present invention can be formed.
Is formed. The upstream portion 81 of the honeycomb structure 80 surrounded by the outer frame corresponds to the first filter portion 11a, and the downstream portion 82 of the honeycomb structure 80 surrounded by the outer frame corresponds to the second filter portion 11b. Is equivalent to Also in this example, whichever of the first filter portion 11a containing the synthetic zeolite and the second filter portion 11b containing the inorganic adsorbent may be arranged on the upstream side with respect to the ventilation direction of the air purification filter 11.

Next, the first and second filter sections 11a, 11a
An example of another manufacturing method b will be briefly described. Until the honeycomb structure 32 is manufactured, the manufacturing method is the same as the manufacturing method described above. In the above-described example, the porous honeycomb structure 32 was impregnated with the synthetic zeolite powder (several μm) or the inorganic adsorbent powder (several μm).
The granular synthetic zeolite processed into pellets or the granular inorganic adsorbent is attached to the honeycomb structure 32 with an adhesive. FIG. 5 is a partially enlarged cross-sectional view of the air purification filter 11 of the manufacturing method according to the present embodiment. Particulate synthetic zeolite 3 without gaps over the entire surface of corrugated sheet 30 and thin sheet 31
6a or the granular inorganic adsorbent 36b is fixed with a nonflammable adhesive. Then, the honeycomb structure 32 is placed in an electric furnace and subjected to a heat treatment at 100 ° C., which is lower than the heat-resistant temperature of the adhesive, for 2 hours to remove all gaseous organic impurity components contained in the adhesive and causing surface contamination. The air purification filter 11 is manufactured by desorption / removal. Fig. 5 Processing air
And passes through a cylindrical space 37 having a pseudo-half-moon-shaped cross section. As shown in FIG. 6, a granular synthetic zeolite 36a or the granular inorganic adsorbent 36b is made of a non-flammable adhesive over the entire surface of the honeycomb structure 32 formed by combining the chevron sheet 38 and the thin sheet 31 with no gap. By adhering, the air purification filter 11 may be manufactured. In the case of FIG. 6, the processing air passes through a cylindrical space 40 having a triangular cross section.

FIGS. 7 (a) and 7 (b) show an air purification filter 70 according to another embodiment of the present invention, which is constructed using a casing, and FIG. 7 (a) is an AA cross section of FIG. , (B) are BB cross sections of (a). In the air purification filter 70 according to this embodiment, as shown in FIG.
The synthetic zeolite pellets 71a are filled into a hollow cylindrical casing 72a having a large number of vents 73 on the inner and outer surfaces to form a first filter portion 70a, and the inorganic adsorbent pellets 71b are similarly transferred to the inner and outer surfaces. The second filter portion 70b is formed by filling a hollow cylindrical casing 72b having a large number of vents 73. However,
Since the lower surface of the casing 72a and the upper surface of the casing 72b are closed, the processing air passes through the packed layer of the pellets 71a in the casing 72a when flowing from the inside to the outside of the casing 72a. Next, the processing air passes through the space between the outer cylinder of the casing 72a and the outer cylinder 74, and flows from the outer cylinder of the casing 72b into the packed bed of the pellets 71b. After that, the casing 7
2b and out of the filter 70.
Note that the flow direction of the processing air is indicated by an arrow 75 in FIG. In FIG. 7, the first filter unit 70a is arranged on the upstream side, and the second filter unit 70b is arranged on the downstream side. However, the embodiment in which the order is reversed is also an embodiment of the present invention. .

When the pellets obtained by mixing the powder of the synthetic zeolite or the inorganic adsorbent with an inorganic binder and fixing the pellet to a support are mixed with, for example, city water in the mixture of the powder and the inorganic binder to form a clay. Granulate into pellets of about 0.3 to 0.8 mm with a granulator. This is sprayed on a support to which an inorganic and nonflammable adhesive has been previously attached by using high-speed air, whereby the filter of the present invention as shown in FIGS. The support is not necessarily limited to the honeycomb structure, but may be a three-dimensional network structure such as rock wool. In the latter, the air to be treated passes across the network structure, so that the air resistance is large, but the chance of contact with the synthetic zeolite or the pellets of the inorganic adsorbent is larger than in the honeycomb structure.

Since the air purification filters 11 and 70 manufactured in this manner do not contain flammable substances in the constituent materials, when the air purification filters 11 and 70 are mounted on the ceiling of a clean room or a clean bench, they are made of flammable substances. Compared to the case where a conventional chemical filter based on activated carbon is installed on the ceiling, the safety in disaster prevention is significantly improved.

Organic substances which are generated in a high-level cleaning apparatus for producing semiconductors and cause surface contamination are organic siloxane generated from a sealant, phosphate ester generated from a flame retardant in a building material, and a plasticizer in a building material. Generated from phthalate, HMD generated from resist adhesive
S, limited to high boiling point and high molecular weight organic compounds such as BHT generated from cassette antioxidants. The sources of these organic substances are components of a high-level cleaning device such as a clean room or various articles used for manufacturing existing inside the high-level cleaning device. Therefore, the air purification filters 11 and 70
The role of is to remove from the circulating air high-boiling-point, high-molecular-weight organic compounds that mainly cause surface contamination inside the advanced cleaning equipment and reduce the concentration of these organic substances inside the advanced cleaning equipment.

[0037]

Next, working effects of the air purifying filter according to the embodiment of the present invention described above will be described with reference to working examples.

First, the problem that a gaseous organic impurity is generated from inside a chemical filter, which the conventional chemical filter has, will be specifically verified. Clean room air treated with two types of commercially available chemical filters using granular activated carbon and fibrous activated carbon and a chemical filter using ion exchange fiber, respectively, and air in the clean room is cooled with liquid nitrogen to condense and remove impurities. FIG. 8 shows the results of measuring the change over time in the contact angle of the surface of the silicon wafer with an oxide film in a total of four atmospheres of dry air. The contact angle measured by dropping ultrapure water onto the surface is a simple method to evaluate the degree of organic contamination on the surface. Immediately after cleaning, the surface of a silicon wafer or glass with an oxide film free from organic contamination is easily water-compatible, that is, hydrophilic, and has a small contact angle. However, those surfaces contaminated with organic matter are water-repellent, that is, hydrophobic, and have a large contact angle. For example, for a glass substrate surface left in a clean room atmosphere, a contact angle measured by dropping ultrapure water and an X-ray photoelectron spectroscopy (X
PS: X-ray Photoelectron Sp
It is known that the surface contamination of the organic matter measured by the method (electroscopy) has a correlation as shown in FIG. For the surface of the silicon wafer with an oxide film, there is almost the same correlation between the contact angle and the organic surface contamination. Thus, there is an extremely strong correlation between the magnitude of the contact angle of water on the substrate surface and the contamination of the organic substance surface.

The following can be understood from the results shown in FIG. The ion-exchange fiber is originally intended to adsorb and remove water-soluble inorganic impurities, cannot adsorb organic substances, and generates gaseous organic substances. An increase in the contact angle of about 10 ° after one day of standing is observed. On the other hand, the contact angle does not increase in the dry air atmosphere, since almost no gaseous organic matter is contained. Two types of activated carbon filters that should originally prevent organic surface contamination are:
The contact angle increased by about 10 ° when left for a day, indicating that there was almost no effect of preventing surface contamination. 2 using activated carbon
The reason why some kinds of chemical filters have no effect is as follows.
This is because surface organic contaminants such as an organic binder, an adhesive, and a sealant are included in the constituent members of the chemical filter, so that the active carbon adsorption effect of the chemical filter is canceled by the degassing of the constituent members. On the other hand, if a filling cylinder is used, there is no such concern if the container of the filling cylinder is made of metal or the like. However, as described above, the filling cylinder has a disadvantage of high pressure loss (ventilation resistance). It is as follows.

Next, the air purification filter 11 of the present invention described above with reference to FIG. 2 was actually manufactured. First filter unit 1
1a is a configuration in which a synthetic zeolite having a pore size of 8 Å is fixed to a honeycomb structure. The second filter portion 11b has a configuration in which a powdered acid-treated montmorillonite (activated clay) of several μm is fixed to the honeycomb structure. The montmorillonite is a name given to a clay mineral having a chemical composition of Al ₄ Si ₈ (OH) ₄ nH ₂₀ produced in Montmorion, France. Pore volume is about 0.37cc / g, specific surface area is about 300
It is about m ² / g. Pore diameter occupying 4 pores in total pore volume
The ratio of the pore volume in the range of 0 Å to 600 Å is as high as 22%.
(Activated clay) can physically adsorb BHT or siloxane, whose molecular size, which cannot be adsorbed by a synthetic zeolite having a pore diameter of 8 Å, is larger than 8 Å, in the pores of the activated clay.

Here, among the organic contaminants detected from the surface of the substrate in a cleaning apparatus such as a clean room or a clean bench, the most frequent types are DOP and DBP. These are contained in large amounts in the vinyl chloride material and have a molecular diameter of 6
In the range of Angstroms to 8 Angstroms.
Therefore, if the pore size of the synthetic zeolite is set to 7 Å or more, most of the gaseous organic substances that cause organic contamination on the substrate surface can be removed by the first filter portion 11a. However, BHT and siloxane having a molecular size larger than 8 angstroms are also detected to some extent from the surface of the substrate in the cleaning apparatus, and cannot be removed by the first filter section 11a.
Removed by b.

The first and second filter units 11 according to this embodiment
Each of a and 11b has a structure in which a thin sheet having no unevenness is sandwiched between adjacent corrugated sheets as shown in FIG. The thickness of the filter in the ventilation direction is 10 cm, the velocity of the ventilation air is 0.6 m / s, and the total surface area of the sheet per unit volume of the filter in contact with the processing air that is passed through the filter is 300
It was 0 m ² / m ³ .

The honeycomb structure of the first filter portion 11a has an effective pore diameter of 8 angstroms and a size of 3 μm.
The porous honeycomb structure was immersed in a slurry prepared by dispersing a water-repellent synthetic zeolite powder together with a 3 μm powder of a kaolin mineral as an inorganic binder and a silica sol, followed by drying to prepare a porous honeycomb structure. As the inorganic binder,
In addition to a mixture of kaolin mineral and silica sol, talc, bentonite, sodium silicate, silica or alumina may be used. Next, the honeycomb structure of the second filter portion 11b is made of activated clay 3 having an effective pore diameter of mainly 20 Å to 1000 Å.
The porous honeycomb structure described above was immersed in a slurry in which a powder of μm was dispersed together with silica sol as an inorganic binder, and then dried to produce a porous honeycomb structure. The physical adsorption capacity of activated clay for gaseous organic impurities is comparable to that of activated carbon.

The thickness of the synthetic zeolite inorganic material layer of the first filter portion 11a is 100 μm, and its weight composition ratio is synthetic zeolite: kaolinite: silica = 70%:
The thickness of the inorganic material layer of activated clay of the air purification filter 11b was 10 μm, and the weight composition ratio was activated clay: silica = 87%: 13%. In each of the first and second filter portions 11a and 11b, the density of the entire filter is about 250 g / liter, and the density occupied by the inorganic material layer is the first filter portion 11a.
About 90 g / liter (about 36% of the whole filter), and about 9 g / liter (about 3.6% of the whole filter) in the second filter portion 11b. First filter unit 11a
The reason why the amount of the inorganic adsorbent of the activated clay provided in the second filter portion 11b is reduced to about 1/10 as compared with the amount of the synthetic zeolite provided in the first filter part 11b is as follows. As will be described later, the synthetic zeolite does not affect moisture control of the atmosphere in the cleaning device as compared with activated carbon because it has less moisture adsorption and desorption with respect to the change in relative humidity. However, inorganic adsorbents such as activated clay are hydrophilic and have the same amount of water adsorption and desorption as activated carbon. Further, among the organic contaminants detected from the surface of the substrate in the cleaning device, DOP and DBP are the types having the largest amounts. These are first filter sections 11a with synthetic zeolites.
Can be removed. On the other hand, BHT or D5 which cannot be removed by the first filter unit 11a and is removed by the second filter unit 11b.
(Pentamer siloxane) concentration in air is DOP or DBP
Compared with the concentration of, the amount detected from the silicon wafer surface is also small. Therefore, the second filter unit 1
The amount of the inorganic adsorbent of the activated clay provided in 1b can be smaller than that of the synthetic zeolite of the first filter portion 11a.

As shown in FIG. 10, the air purifying filter 11 according to the present invention, together with the fan 93 and the HEPA filter 94, is stored in a storage 9 placed in a clean room 90.
1 was attached to the ceiling. Clean room 9 with fan 95
The clean room air 99 is taken into the storage 91 from the atmosphere inside the storage room 91 through the inflow port 96, and the air purification filter
Processing room 9 filled with clean room air processed in 1
The contact angle was measured by leaving the silicon wafer substrate 92 with an oxide film without organic contamination immediately after the cleaning for 3 days in the atmosphere of No. 7. Measurement of contact angle after leaving for 3 days in the same atmosphere (cleaning → leaving for 3 days → measuring contact angle → cleaning → leaving for 3 days →
The contact angle measurement was repeated every 15 days, and the deterioration over time of the adsorption performance of the air purification filter 11 was measured. The storage 91 is made of a material that does not generate gaseous organic impurities.
In No. 7, there is no generation of gaseous organic impurities caused by the storage itself.

The air in the processing chamber 97 passes through the grating 101 along the flow direction indicated by the arrow in FIG.
Return to 04. The circulating air flow rate in the storage 91 is 20 m
³ / min, and in order to process this circulating air 98,
The amount of synthetic zeolite contained in the first filter portion 11a, which is a component of the air purification filter 11, is 2 kg,
The used amount of activated clay contained in the second filter portion 11b, which is the same component, was 0.2 kg. The intake amount of the clean room air 99 was set at 0.8 m ³ / min, which is 4% of the flow rate of the circulating air 98. An air amount corresponding to the intake amount is discharged from the outlet 100. The total volume of the storage is 12 m ³ and the number of ventilation per hour is 10
It was 0 times.

For comparison, in the storage 91 of FIG. 10, the first filter unit 11a provided with the synthetic zeolite is used.
Only the second filter unit 11b provided with activated clay
Even when was removed, the cleaned silicon wafer substrate with an oxide film was allowed to stand for 3 days to measure the contact angle, and this contact angle measurement was repeated every 15 days. Furthermore, the first filter unit 11a and the second filter unit 1 according to the present invention
The same measurement was performed when no 1b was provided, that is, when the gaseous organic impurities contained in the clean room air flowed directly into the storage without being removed.

The contact angle on the surface of the silicon wafer with the oxide film immediately after the cleaning was 3 °. Maintaining a contact angle of 6 ° or less on the surface of the silicon wafer with the oxide film exposed for 3 days is a necessary condition for the atmosphere of the storage to prevent the deterioration of device quality due to gaseous organic impurity contamination. Assume that

FIG. 11 shows the measurement results. The storage 91 is
In the three cases, that is, the case where the air purification filter 11 according to the present invention was provided, the case where only the first filter portion 11a was provided, and the case where the gaseous organic impurities were not removed, the case was exposed to the atmosphere in the storage 91. 6 is a comparison of the change over time of the contact angle on the surface of a silicon wafer with an oxide film.

The contact angle of the surface of the silicon wafer with the oxide film exposed to the atmosphere in the storage where the gaseous organic impurities are not removed increases by 26 ° to 30 ° after being left for 3 days.
Regarding the advanced cleaning device provided with the air purification filter 11 according to the present invention, the contact angle of the silicon wafer with the oxide film after being left for 3 days was kept at 4 ° or less immediately after the start of use (elapsed time: 0 days). . However, as the ventilation time increases, the adsorption performance of the air purification filter 11 decreases, and the concentration of gaseous organic impurities contained in the air after passing through the air purification filter also increases. That is, the contact angle of the surface of the silicon wafer with the oxide film exposed to the treated air on the downstream side for a certain time increases with the increase of the ventilation time to the air purification filter 11. It can be seen that the use time of the air purification filter 11 is about 8 months until the contact angle of the surface of the silicon wafer with the oxide film exposed to the air after passing through the air purification filter 3 for 6 days reaches 6 °. On the other hand, among the first filter unit 11a and the second filter unit 11b constituting the air purification filter 11, an advanced cleaning device having only the first filter unit 11a and lacking the second filter unit 11b is used. Immediately after the start (elapsed time: 0 days), the contact angle of the silicon wafer with the oxide film after standing for 3 days had already exceeded 5 °. Moreover, the usage time of the first filter unit 11a is short until the contact angle of the surface of the silicon wafer with the oxide film exposed to the air after passing through the first filter unit 11a having the synthetic zeolite for 3 days reaches 6 °. It turns out that it is two months.

In order to investigate the reason in more detail, as shown in FIG. 12, the air purifying filter 11 (consisting of the first and second filter portions 11a and 11b) of the present invention used in FIG. 91 'clean room air 9
9 and the case where only the first filter portion 11a is attached to the intake 96, four types of gaseous organic impurities DOP, DBP, The effect of preventing contamination of the substrate surface against BHT, D5 (pentamer siloxane) was measured, and the two cases were compared. 12, unlike FIG. 10, the air in the processing chamber 97 passes through the grating 101 along the flow direction indicated by the arrow in FIG.
That is, FIG. 12 corresponds to the case where the circulation path in FIG. 10 is closed, and the air in the storage flows in one direction without circulating. The concentrations of DOP and DBP are several tens of ppt and BH respectively.
T and D5 were several ppt each.

After leaving a clean silicon wafer 92 with an oxide film immediately after cleaning for only 4 hours in the atmosphere of the clean room 90 and the atmosphere of the storage 91 'in FIG. 12, the DOP, DBP , BHT,
The amount of organic substance surface contamination by D5 was measured and compared to evaluate the effect of preventing organic substance surface contamination. Table 3 shows the results.

[0053]

[Table 3]

A 4-inch p-type silicon wafer was used to evaluate the amount of organic surface contamination. A combination of a heated gas desorption device and a gas chromatograph mass spectrometer was used to analyze and measure the organic substances attached to the wafer surface. In addition, the surface contamination prevention rate was determined as follows based on gas chromatography.

Surface contamination prevention rate = (1- (B / A)) × 100 (%) A: Peak area of contaminated organic substance detected from wafer surface in clean room atmosphere B: Wafer surface in storage atmosphere Area of the peak of the pollutant organic substance detected from

It is clear from Table 3 that among the four gaseous organic contaminants DOP, DBP, BHT and D5, DOP,
Since the molecular size of each of the DBPs was smaller than 8 Å, it was almost completely removed by the first filter portion 11a provided with the synthetic zeolite having an effective pore size of 8 Å. However, since the size of each molecule of BHT and D5 is larger than 8 Å,
It is not removed by the first filter portion 11a provided with the synthetic zeolite having an effective pore size of 8 Å, and is almost completely removed by the second filter portion 11b provided with activated clay whose effective pore size is mainly distributed in the range of 20 Å to 1000 Å. Was removed. That is, like the air purification filter 11 of the present invention, the first filter unit 11a provided with the synthetic zeolite and the first filter unit 11a
A second filter unit having an inorganic adsorbent having a property of adsorbing gaseous organic impurities disposed on the upstream side or the downstream side of a and having an effective pore diameter larger than the effective pore diameter of the synthetic zeolite. 11b can completely prevent surface contamination of organic matter due to the atmosphere of a highly purified device such as a clean room. When only the first filter section 11a provided with the synthetic zeolite is used, the pore size of the synthetic zeolite is smaller than that of the synthetic zeolite. Since large molecules cannot be adsorbed, it is not possible to completely prevent organic matter surface contamination from the atmosphere of a high-purity equipment. This was also apparent from the measurement results in FIG.

Next, the water-repellent synthetic zeolite according to the present invention,
The reason why a material having an effective pore diameter of preferably 7 Å or more is preferably explained.

Although organic substances causing surface contamination of organic substances in a clean room or a clean bench have been described above, the surface of a silicon wafer handled in an air atmosphere of a clean room or a clean bench has a natural oxidation on its surface even though there is some difference. A film has been formed, and therefore the wafer surface is hydrophilic. It is well known that glass substrates handled in the air atmosphere are also hydrophilic due to the physical properties of the glass itself. An organic substance derived from an air atmosphere that contaminates the hydrophilic surface of a silicon wafer or a glass substrate on which such a natural oxide film is formed should have a hydrophilic group that is well compatible with the hydrophilic surface. In fact, the organic substances that cause surface contamination described above are high-boiling, high-molecular-weight hydrophobic organic substances having a carbon double bond and a benzene ring chemical structure, and have a hydrophobic group. These organics also have hydrophilic groups that cause contamination of the clean hydrophilic surface. However, once the hydrophilic clean surface of the silicon wafer or glass substrate is contaminated with these organic substances, the contaminated surface portion changes to the same hydrophobicity as the attached organic substances. Since the hydrophobic group of the hydrophobic organic substance is easily bonded to the hydrophobic surface, the surface contamination of the organic substance rapidly progresses to form a multimolecular layer of the organic substance.

Since organic substances causing surface contamination are high-boiling and high-molecular-weight hydrophobic and have a hydrophobic group, it is preferable to select a water-repellent zeolite because it has an affinity for the hydrophobic group. . However, as a second best option, these organic substances causing surface contamination also have hydrophilic groups at the same time, so that hydrophilic zeolites having affinity for hydrophilic groups can be used. However, when a water-repellent zeolite is used, the amount of water adsorbed in the air is smaller than that of activated carbon or hydrophilic zeolite, so the adsorption capacity of the original gaseous organic substance of the zeolite porous structure is reduced by water adsorption. Nothing. Therefore, when a water-repellent zeolite is used as an organic adsorbing material, its life is longer than that of activated carbon or hydrophilic zeolite having the same porous structure. On the other hand, activated carbon and hydrophilic zeolite having a porous structure have a large amount of water adsorbed in the air, so the original adsorption capacity of the porous structure is greatly reduced by water adsorption, and the remaining adsorbed amount excluding the water adsorbed component is removed. Since only the capacity is involved in the adsorption of organic substances, its life is shorter than that of the water-repellent zeolite.

The basic component of zeolite is silica (Si
O ₂ ) and alumina (Al ₂ O ₃ ). As the weight ratio of SiO ₂ / Al ₂ O ₃ is increased, the adsorption characteristics greatly change from hydrophilic to hydrophobic. The silica / alumina ratio of the hydrophilic zeolite is about 2 to 5, and the silica / alumina ratio of the water-repellent zeolite is 20 to infinity. As mentioned earlier, water-repellent zeolites have a longer life span as organic sorbent materials than hydrophilic zeolites. However, since the water-repellent zeolite is manufactured using a hydrophilic zeolite as a raw material through a process of dealumination by acid treatment and subsequent heating and drying, the price is higher than that of the hydrophilic zeolite. The largest use of zeolite itself is as a detergent builder, and hydrophilic zeolites are used. In the country, detergent builders account for more than 90% of the total demand for zeolites. Zeolite demand growth is
Because of the growing demand for phosphorus-free detergents overseas (developing countries), it is easy to reduce the cost of hydrophilic zeolites by mass production, but it is difficult to reduce the cost of water-repellent zeolites. Therefore, just because the life of a hydrophilic zeolite is shorter than that of a water-repellent zeolite,
Its cost-effectiveness does not mean that hydrophilicity is inferior to water repellency. The water repellency is determined from the initial cost of the chemical filter (the price of the entire chemical filter as a device including the filter medium and casing) and the running cost (price of the replacement filter medium) determined from the replacement frequency determined by the longevity of the filter medium. It should be comprehensively determined whether zeolite or hydrophilic zeolite is good.

However, from a technical point of view, the water-repellent zeolite is superior to the hydrophilic zeolite in that the adsorption life is long.

Next, the water adsorption characteristics of the synthetic zeolite will be described. FIG. 13 shows a water adsorption isotherm measured for a water-repellent synthetic zeolite having a pore size of 8 Å, a hydrophilic synthetic zeolite having a pore size of 10 Å, and activated carbon in an atmosphere at 25 ° C. With regard to activated carbon, even a small increase in the relative humidity causes a sudden increase in the amount of saturated water absorbed in the air. For example, an unused activated carbon-impregnated chemical filter that hardly adsorbs water is stored in a container having an atmosphere of 20% relative humidity, and the chemical filter is taken out of the storage container to use the filter at a relative humidity of 50%. When exposed to a clean room atmosphere, activated carbon will adsorb a large amount of moisture in the air until it reaches adsorption saturation. 20% relative humidity (0.046 cc / g of water adsorption saturation) and 50%
% (Saturation amount of water adsorption: 0.12 cc / g), the difference of the saturation amount of water adsorption of activated carbon is as high as 0.074 cc / g.
On the other hand, a water-repellent synthetic zeolite having a pore size of 8 angstroms has a relative humidity of 20% (water adsorption saturation amount 0.026 cc).
/ G) and 50% (water adsorption saturated amount 0.034cc / g)
The difference in the amount of water adsorption and saturation was only 0.008 cc /
g. Furthermore, in the case of a hydrophilic synthetic zeolite having a pore size of 10 angstroms, the saturated amount of water adsorption at a relative humidity of 20% is considerably large at 0.262 cc / g. The increase in saturation is only 0.02 cc / g, only 27% of the increase in activated carbon.

As can be understood from FIG. 13, when an air purification filter provided with an unused synthetic zeolite stored in an atmosphere having a relative humidity of 20% or more is used in a clean room atmosphere with a relative humidity of 50%. Even if the relative humidity is adjusted upstream, the synthetic zeolite used in this air purification filter hardly adsorbs moisture in the air regardless of whether it is hydrophobic or hydrophilic. Therefore, there is no problem with the chemical filter containing activated carbon that the relative humidity in the cleaning device provided with the chemical filter becomes lower than a predetermined value.

As with a chemical filter to which activated carbon is impregnated, the temperature and humidity of the atmosphere at the place of use are investigated before shipment, and moisture corresponding to the temperature and humidity is deliberately adsorbed to or desorbed from the activated carbon of the chemical filter, and then sealed. There is no need for troublesome work of shipping. This is because an atmosphere having a relative humidity of 20% or less is in an ultra-dry state that cannot be achieved in a normal working environment, and is usually several tens of percent in a normal working environment. Therefore, activated carbon is used in an air purification filter provided with synthetic zeolite. It is not necessary to adsorb and desorb water before shipping as in the case of an attached chemical filter, and it can be packed and shipped as it is.

In addition, hydrophilic and hydrophobic zeolites having a pore size of 6 Å, hydrophilic and hydrophobic zeolites having a pore size of 8 Å, natural activated carbon starting from coconut shell, and synthetic products starting from petroleum pitch For six types of adsorbents based on activated carbon, the adsorption performance of trace organic substances causing surface contamination contained in a clean room atmosphere (23 ° C., 40% RH) was compared. 0.04 g of each adsorbent was packed in a column having a cross section of 0.15 cm ² , and clean room air was supplied at a rate of 3 L / min. Table 4 shows the experimental conditions. After passing through the adsorbent, the air at 3 liter / min enters from the container itself into the inlet of a 1-liter container without generation of gaseous organic impurities, and exits from the outlet. A silicon wafer substrate with an oxide film without organic contamination immediately after washing was left in this container for only 20 hours, and the contact angle was measured. Washing → leave for 20 hours → measurement of contact angle → washing → leave for 20 hours → measurement of contact angle →...) Was continuously repeated to measure the deterioration over time of the adsorption performance of various adsorbents.

[0066]

[Table 4]

FIG. 1 shows the change in contact angle for various adsorbents.
It is shown in FIG. The measured value of the contact angle immediately after the cleaning of the wafer surface was about 3 °. In FIG. 14, a curve 40 shows a case where a silicon wafer with an oxide film without organic matter contamination immediately after cleaning was exposed to clean room air before ventilating the adsorbent, and a curve 41 shows a hydrophilic zeolite having a pore diameter of 6 Å. Curve 42 is the case where the air was exposed to the clean room air after passing through the adsorbent provided with the hydrophilic zeolite having a pore diameter of 8 Å.
The curve 46 represents the case where the adsorbent provided with the hydrophobic zeolite having the pore diameter of 6 Å was exposed to the clean room air after being ventilated. Curve 43 is the case when exposed to clean room air after ventilating the adsorbent mainly composed of natural product type activated carbon, and curve 43 is the case where it is exposed to clean room air mainly containing synthetic type activated carbon. In this case, the agent is exposed to clean room air after ventilation.

The following can be seen from FIG. 1. The adsorption performance was as follows: Curve 46 (hydrophobic zeolite with a pore size of 8 Å)> Curve 42 (hydrophilic zeolite with a pore size of 8 Å)> Curve 43 (natural product activated carbon)> Curve 45 (hydrophobic zeolite with a pore size of 6 Å) )> Curve 41 (hydrophilic zeolite having a pore size of 6 Å)> curve 44 (synthetic activated carbon). Particularly, synthetic activated carbon is bad. 2. A hydrophilic zeolite with a pore size of 6 Å (curve 41) has an aeration time of over 30 hours, and a hydrophobic zeolite with a pore size of 6 Å (curve 45) and natural activated carbon (curve 43) have an aeration time of 50 hours.
Around the time, the adsorption performance starts to decrease. 3. Hydrophilic zeolite with a pore size of 8 Å (curve 42) adsorbs up to 120 hours, and hydrophobic zeolite with a pore size of 8 Å (curve 46) and synthetic activated carbon (curve 44) adsorb up to 200 hours. Performance does not decrease. 4. In the early stage of use when the adsorption performance does not decrease, the pore size is 6
Angstrom hydrophilic zeolite (curve 41) and 8 Å pore size hydrophilic zeolite (curve 4)
Comparing 2), the hydrophilic zeolite having a pore diameter of 6 Å (curve 41) changes from 3 ° to 7.8 ° while the hydrophilic zeolite having a pore diameter of 8 Å (curve 42) changes from 3 ° to 3. The change was 5%. Similarly, in the early stage of use where the adsorption performance does not decrease, a hydrophobic zeolite having a pore size of 6 Å (curve 45) and a pore size of 8
Comparing the hydrophobic zeolite of Angstrom (curve 46), the hydrophobic zeolite of 6 angstrom pore diameter (curve 45) changes the hydrophobic zeolite of 8 angstrom pore diameter (curve 46) against the change of 3 ゜ → 6.4 ゜. )
Was a change from 3 ゜ to 3.1 ゜. Hydrophilic and hydrophobic zeolites with a pore size of 8 Å can almost completely adsorb and remove trace organic substances that cause surface contamination contained in the clean room atmosphere, whereas hydrophilic and hydrophobic zeolites with a pore size of 6 Å are It can be seen that there is a trace amount of organic substances that cause surface contamination that cannot be removed by adsorption and pass through. 5. The adsorption performance of the hydrophilic and hydrophobic zeolites having a pore size of 8 Å (curves 42 and 46) and the activated carbon based on natural products (curve 43) was as follows: hydrophilic and hydrophobic zeolites having a pore size of 6 Å (curves 41 and 45),
And much better than the adsorption performance of synthetic activated carbon (curve 44). Zeolites cannot adsorb molecules larger than the pore size. Thus, hydrophilic and hydrophobic zeolites with a pore size of 8 Å (curves 42 and 4).
The fact that trace organic substances that cause surface contamination contained in the clean room atmosphere could be almost completely absorbed and removed in 6) means that the surface contamination contained in the clean room atmosphere targeted in the experiment of FIG. It shows that the molecular size of the majority of trace organics is less than 8 Å. On the other hand, hydrophilic and hydrophobic zeolites with a pore size of 6 angstroms have almost satisfactory adsorption performance as compared with synthetic activated carbon, but there are trace organic substances that can not be adsorbed and removed and cause surface contamination that passes through. This indicates that the molecular size of the trace organic matter passed through was 6 Å to 8 Å.

As described above, in the preferred embodiment of the present invention,
Although the description has been given of the advanced cleaning apparatus (so-called clean room) in the whole process of manufacturing SI and LCD, the present invention is not limited to such an embodiment. High-level cleaning equipment of various scales, such as a local high-level cleaning device called a mini-environment, a clean bench, a clean chamber, and various stockers for storing clean products, a processable air volume of the air purification filter, a circulating air volume, and outside air intake Various embodiments are conceivable depending on the processing environment such as the ratio of the amount of air and the presence or absence of gaseous organic impurities from inside the advanced cleaning device.

For example, using a 300 mm diameter silicon wafer, a 256 Mbit DRAM or a 1 Gbit DRAM
Semiconductor production is about to start around 1999.
In such a semiconductor manufacturing apparatus, an inert gas such as nitrogen or argon is supplied from an inert gas supply device until the reaction process is started after a wafer is introduced into the chamber in the apparatus and the wafer is introduced into the chamber. To fill. This inert gas has an extremely high purity specification, and the inert gas itself does not cause surface contamination of the wafer. However, in order to turn on and off the supply of the inert gas, a valve is provided between the inert gas supply device and the chamber, and gaseous organic substances that cause contamination of the wafer surface are generated from the constituent materials of the valve. By providing the air purifying filter according to the present invention in the gas flow path between the valve and the chamber, the air purifying filter does not generate any gaseous organic contaminants from itself, but can generate various gaseous organic contaminants generated from the valve. Removing the material helped to prevent surface contamination of the wafer and improve quality.

[0071]

According to the present invention, the following effects can be obtained. (1) In preventing contamination of the substrate surface handled by the cleaning device, a substrate suitable for the production of semiconductors and LCDs, etc. by adsorbing and removing gaseous organic impurities that cause substrate surface contamination contained in the atmosphere. It was possible to produce clean air from which gaseous organic impurities causing surface contamination were removed. In the manufacture of semiconductors and LCDs,
By using this clean air as the atmosphere of a cleaning device to which the substrate surface is exposed, organic contamination of the substrate surface could be prevented. (2) In (1), the synthetic zeolite is used as an adsorbent for adsorbing / removing gaseous organic impurities, and the synthetic zeolite is used as an adsorbent for adsorbing / removing gaseous organic impurities. By appropriately selecting and combining various inorganic substances having a large effective pore diameter, it is possible to provide an air purifying filter containing no combustible materials in the constituent material, and a purifying device constructed using this air purifying filter is: It was superior in terms of disaster prevention in comparison with a cleaning device constructed using a conventional activated carbon adsorbent or an air exchange filter made of ion exchange fibers. In addition, it is possible to provide an air purification filter composed only of a material that does not generate gaseous organic substances that cause substrate surface contamination, and a cleaning device constructed using this air purification filter is a conventional activated carbon adsorbent. Organic contamination on the substrate surface could be more completely prevented as compared to a cleaning device constructed using an air purification filter made of ion exchange fibers.

[Brief description of the drawings]

FIG. 1 is a perspective view of an air purification filter according to an embodiment of the present invention, where (a) is an exploded view and (b) is an assembly view.

FIG. 2 is a schematic exploded view of first and second filter units.

FIG. 3 is an exploded view of an air purification filter according to another embodiment.

FIG. 4 is an explanatory diagram of an air purification filter according to another embodiment.

FIG. 5 is a partially enlarged view of an air purification filter obtained by laminating a corrugated sheet and a thin sheet.

FIG. 6 is a partially enlarged view of an air purification filter in which a chevron sheet and a thin sheet are laminated.

FIGS. 7A and 7B show an air purification filter according to another embodiment of the present invention constituted by using a casing, wherein FIG. 7A is an AA cross section of FIG. It is a cross section.

FIG. 8 is a graph showing a change with time of a contact angle of a wafer surface exposed to processing air by a chemical filter.

FIG. 9 is a graph showing a relationship between a contact angle and a carbon deposition amount.

FIG. 10 is an explanatory view of an embodiment in which the air purification filter according to the present invention is mounted on the ceiling of a storage placed in a clean room.

FIG. 11 is a graph showing the effect of the air purification filter according to the present invention.

FIG. 12 is an explanatory view of another embodiment in which the air purifying filter according to the present invention is attached to a cleaning room air intake of a storage placed in a clean room.

FIG. 13 is an adsorption isotherm of water adsorption on synthetic zeolite and activated carbon.

FIG. 14 is a graph comparing the adsorption performance of trace amounts of organic substances that cause surface contamination of various adsorbents.

[Explanation of symbols]

 11 air purification filter 11a first filter section 11b second filter section

Continued on the front page (51) Int.Cl. ⁶ Identification code FI B01J 20/12 B01J 20/12 Z 20/14 20/14 20/18 20/18 Z 20/32 20/32 Z

Claims (12)

[Claims] 1. An adsorbent for adsorbing gaseous organic impurities, which is adjacent to an upstream or downstream side of a gas-permeable first filter section provided with a synthetic zeolite, and an effective pore diameter of the synthetic zeolite. An air purification filter, comprising a second filter portion having air permeability provided with an inorganic adsorbent having a larger effective pore diameter. 2. A structure in which the first filter section has a synthetic zeolite fixed to the surface of a support, and the second filter section has the inorganic adsorbent fixed to the surface of a support. The air purification filter according to claim 1, wherein: 3. A structure in which the first filter section is configured to impregnate a support with a suspension in which the synthetic zeolite is dispersed and then dry the suspension to fix the synthetic zeolite on the surface of the support. The second filter unit is configured to impregnate the support with a suspension in which the inorganic adsorbent is dispersed and then dry the suspension to fix the inorganic adsorbent on the surface of the support. Item 3. An air purification filter according to Item 2. 4. A method according to claim 1, wherein the first filter section is formed by fixing a pellet formed of synthetic zeolite powder to a support, and the second filter section is formed of a pellet formed of the inorganic adsorbent powder. The air purification filter according to claim 1, wherein the filter is fixed to a support. 5. A support having air permeability is divided into two regions with a boundary surface intersecting with the direction of ventilation of the support as a boundary, and in one region, the surface of the support is made of synthetic zeolite or synthetic zeolite. The first filter portion is formed by fixing the pellets formed of the powder, and the second filter portion is formed by fixing the pellets formed of the inorganic adsorbent or the powder of the inorganic adsorbent on the surface of the support in the other region. The air purification filter according to claim 2, wherein the air purification filter is formed. 6. A method for fixing a pellet formed of synthetic zeolite or a powder of synthetic zeolite on the surface of the support, and / or a pellet formed of an inorganic adsorbent or a powder of inorganic adsorbent on the surface of the support. Talc, kaolin mineral, bentonite,
3. A fixing aid comprising at least one of sodium silicate, silica and alumina.
The air purification filter according to any one of 3, 4, and 5. 7. The inorganic adsorbent of the second filter section,
Diatomaceous earth, silica, alumina, mixture of silica and alumina, aluminum silicate, activated alumina, porous glass, hydrated magnesium silicate clay mineral with ribbon-like structure,
The air purification filter according to any one of claims 1, 2, 3, 4, 5, and 6, comprising at least one of activated clay and activated bentonite. 8. The synthetic zeolite according to claim 1, wherein said synthetic zeolite has an effective pore diameter of at least 7 angstroms and said inorganic adsorbent of said second filter has a total volume of pores distributed in a range of 15 to 300 angstroms of 0 to 0 per weight. .2cc
/ G or more, or the specific surface area of the pores of the inorganic adsorbent is 100 m ² / g or more, any one of claims 1, 2, 3, 4, 5, 6, and 7. An air purification filter according to any one of the preceding claims. 9. The air purification filter according to claim 2, wherein the support is a honeycomb structure. 10. The air purification filter according to claim 9, wherein the honeycomb structure is a structure containing inorganic fibers as an essential component. 11. The first filter portion is formed by filling the pellets of the synthetic zeolite into a casing, and the second filter portion is formed by filling the pellets of the inorganic adsorbent into another casing. The air purification filter according to claim 1, wherein: 12. The method according to claim 1, wherein said synthetic zeolite is water-repellent.
The air purification filter according to any one of 8, 9, 10, and 11.