JPH10249237A - Air purifying apparatus, method for cleaning hermetically closed space using the same and hermetically closed space - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air purifying apparatus widening an effective area permitting free work to obtain an ultra-clean space, a method for purifying a hermetically closed space using the purifying apparatus and the hermetically closed space. SOLUTION: In an air purifying apparatus equipped with an ultraviolet source, a photon discharge material and an electric field setting and charge particles collecting electrode material, the box body 13 surrounded by an outer frame is provided and the ultraviolet source 2 and the photon discharge material 3 are arranged to the central part of the box body 13 and electrode materials 4-1-4-3 are provided to the outer peripheral part thereof to be integrated therewith and an air inflow port is provided to the lower part of the central part of the box body 3 and an air outflow port is provided to the outer peripheral side surface part thereof. In this purifying apparatus, a photocatalyst can be arranged to the irradiation surface irradiated with ultraviolet rays in the box body 13 and the purifying apparatus is arranged to the ceiling part of a hermetically closed space so that the air inflow part is turned downwardly and air in the hermetically closed space is passed through this apparatus to be purified.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to gas purification.
In particular, the present invention relates to a cleaning device for purifying gas in a closed space, a method for cleaning a closed space using the device, and a closed space.

[0002]

2. Description of the Related Art The prior art will be described below by taking air purification in a clean room in a semiconductor manufacturing plant as an example.
Conventionally, the cleaning of the space in the clean room has been performed by a method using a HEPA or ULPA filter. This method is the traditional clean room and clean goose,
It is effective for cleaning benches and other cleans, and is widely used. However, the removal of fine particles by this method has the following problems since it is necessary in principle to supply a gas containing fine particles to a filter. (1) Particles may be generated due to forced ventilation,
In this case, there is a limit to the attainable cleanliness (creation of an ultra-clean space). (2) Since the pressure loss increases, the operating cost increases. (3) Recently, it has been said that a gaseous substance such as boron is generated depending on how the filter is used, so that the filter becomes a secondary pollution source, and there is a limit in the performance of collecting ultrafine particles.

[0003] Against such a background, the present inventors have proposed:
Methods and apparatuses for purifying a space by generating photoelectrons by irradiating a photoelectron emitting material with ultraviolet rays have already been proposed (for example, Japanese Patent Publication No. 3-5859, Japanese Patent Publication No. 6-34941, and Japanese Patent Publication No. Nos. 7-110342, JP-B-6-74909, JP-B-6-74910 and JP-B8-211). These methods and apparatuses can be implemented with sufficient effects depending on the field of use, type of apparatus, structure, shape, and required performance, but there is still room for improvement. next,
Improvements will be described with reference to the prior art. A conventional technique will be described with reference to FIG. 9 by taking an example of cleaning air in a wafer storage (stocker) in a semiconductor factory.

[0004] In FIG. 9, the air in the wafer storage 1, which is an enclosed space, is cleaned by an ultraviolet lamp 2, a photoelectron emitting material (quartz glass of an ultraviolet irradiation window coated with Au 50 ° as a photoelectron emitting material) 3, electrodes 4 is performed. That is, when the photoelectron emission material 3 is irradiated with ultraviolet rays in a state where an electric field is formed between the photoelectron emission material 3 and the electrode 4, the photoelectrons 5 are emitted from the photoelectron emission material 3. Here, the fine particles 6 in the wafer storage 1 are charged by the above-mentioned photoelectrons 5 in the fine particle charge collecting section C composed of an ultraviolet lamp, a photoelectron emitting material 3 and an electrode 4 to become charged fine particles 7. Are collected by the electrode 4 and the inside of the wafer storage 1 is highly purified. 8a, 8b, 8c are ultraviolet lamps 2
Storage 1 caused by temperature rise of charging / collecting section C
This shows the flow of air inside, and by this flow, the fine particles 6 in the storage 1 are effectively moved to the charging / collecting unit C and charged / collected. 9 is a wafer carrier, 10 is a wafer, and 11 is a reflection surface. As described above, the fine particle charge collection unit (C)
Is installed on one side of the wafer storage 1, there is a problem that the storage area (effective work area) B in the space to be cleaned becomes narrow.

[0005]

SUMMARY OF THE INVENTION Accordingly, the present invention solves the above-mentioned problems, and can increase the effective area in which cleaning can be performed freely even in photoelectron cleaning. It is an object to provide a cleaning device, a method for cleaning a closed space using the same, and a closed space.

[0006]

According to the present invention, there is provided a gas cleaning apparatus comprising an ultraviolet ray source, a photoelectron emitting material, and an electrode for setting an electric field and collecting charged particles. A box surrounded by an outer frame, an ultraviolet light source and a photoelectron emission material are provided at the center of the box, and the electrode material is provided and integrated at the outer periphery thereof, and a lower part of the center of the box is provided. And a gas outlet on the outer peripheral side surface. In the gas cleaning device, an irradiation surface to which ultraviolet light in the box is irradiated, for example,
An ultraviolet light source, a charged particle collecting electrode material, a photocatalyst can be disposed on an ultraviolet irradiation surface of a box or the like, and the collecting electrode material follows a gas flow toward an outlet. It is good to install. Further, according to the present invention, in the method for purifying gas in an enclosed space, the gas purifying device is installed on a ceiling of the enclosed space with the gas inlet facing downward, and the gas in the enclosed space is removed. Through the device, and a method for cleaning an enclosed space, wherein the gas cleaning device is installed on the ceiling with the gas inlet facing downward. It is a closed space.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention has been made based on the following four findings. (1) The cleaning of the space has been performed by a method using a filter. This method has the following problems in principle because the air to be cleaned is forcibly ventilated to the filter by a fan. (A) Generation of particulate matter and gaseous matter by forced ventilation. (B) Since the cleaning air is spatially and forcedly circulated (circulated), the articles (eg, wafers) contained in the space are sequentially exposed to the air flow, thereby accelerating the contamination. (C) As the cleanliness is increased due to forced ventilation, the pressure loss increases and the operating cost increases. (D) In ordinary air (outside air), acidic gases such as NOx, SOx, and HCl, alkaline gases such as ammonia and amine, and hydrocarbons (H.
C. ) Exists, and the current filters cannot collect these gaseous harmful components.
These harmful gases are introduced into the space and become a new source of pollution (a cause of pollution) in the space.

(2) In advanced industrial fields such as semiconductors and liquid crystals, removal of particulate matter has been sufficient in the past. However, due to higher quality and refinement of products (more expensive products have higher integration density). In other words, it becomes finer and higher precision), and will be strongly affected by gaseous substances in the future. Therefore, the H.O. level of the clean room air concentration (extremely low concentration such as ppb level) which has not been a problem in the past. C, SO ₂ , HC
It has become necessary to control and remove gaseous pollutants such as l, HF, and NH ₃ ("The 39th Annual Meeting of the Japan Society of Applied Physics", p86, Spring 1992, "Air Purification", Vol. 33,
No. 1, pp. 16-21, 1995, "Ultra Clean Technology" Vol. 6, p29-35,199
4). This is because the presence of these gaseous pollutants has been found to significantly reduce yield (productivity). (A) The clean room in the future advanced industry will require simultaneous removal of particulate matter (fine particles) and gaseous harmful components.

(B) The above-mentioned gaseous harmful components are generated from work in a clean room or from components and equipment of a clean room.
Since the clean room is a closed system and is confined (recently the clean room has a high rate of air circulation in terms of energy saving), the concentration gradually increases and adheres to wafers, glass substrates, and base materials in the clean room, It has an adverse effect. The generation of harmful gases in the above clean room is described in H. Next, C will be described as an example. In a clean room environment where at least a part is made of an organic substance (polymer resin), a trace amount of an organic gas (H.
C) occurs and contaminates the contents (raw materials such as wafers and glass substrates, semi-finished products) in the clean room space. That is, in a clean room space, at least a part thereof includes an organic substance (eg, a plastic container, a packing material, a sealing material,
Adhesive, wall material, etc.), and a very small amount of organic gas is generated from the organic matter. For example, siloxane is generated from the sealing material, and phthalic acid ester is generated from the plastic material that is the material of the storage container.

H. C adheres to substrate such as wafer (adsorption)
The degree of contamination on the substrate surface in the case of
Can be displayed with. H. The problem of the substrate contaminated with C will be described with a specific example. Contamination of the wafer substrate (valuables) by C affects the affinity (fit-in) between the substrate and the resist. When the affinity deteriorates, it affects the resist and the film thickness or the adhesion between the substrate and the resist, resulting in a decrease in quality and a decrease in yield. The contact angle is a contact angle of water wetting, and indicates the degree of contamination of the substrate surface. That is, when a hydrophobic (oil-based) substance is attached to the surface of the substrate, the surface repels water and becomes difficult to wet. Then, the contact angle between the substrate surface and the water droplet increases. Therefore, the contamination degree is high when the contact angle is large, and low when the contact angle is small. (C) Also in the field of consumer use, as seen in the thick building Shinji Road, it is necessary to simultaneously remove these organic gases (eg, aldehydes and chlorine-containing HC), acid gases, and basic gases. ing.

(3) In a field where various fungi and microorganisms are problematic in hospitals, food industries, medicines, etc., in the case of a cleaning system using a filter, a filter or a circulation system (filter and fan, its path, its Peripheral) due to the proliferation of various fungi and microorganisms. (4) A charged particle trapping material is installed in the space, and photoelectrons are emitted by irradiating the photoelectron emitting material with ultraviolet light in an electric field, whereby the particulate matter in the space is forced through the air in the space. It is charged and collected without circulating, and the air is ultra-purified. In addition, in a field where gaseous harmful substances are a problem, if the photocatalyst is installed at a position irradiated with ultraviolet rays, the photocatalyst exerts a photocatalytic action, and gaseous harmful components in the space are decomposed and removed.

Next, each configuration of the present invention will be described. The photoelectron emitting material provided at the center of the box is used for generating photoelectrons for charging particulate matter (fine particles, floating fungi, and microorganisms) by irradiation with ultraviolet rays described below. The photoelectron emitting material may be any material that emits photoelectrons by irradiating ultraviolet rays. The smaller the photoelectric work function, the better. From the viewpoints of effect and economy, Ba, S
r, Ca, Y, Gd, La, Ce, Nd, Th, Pr,
Be, Zr, Fe, Ni, Zn, Cu, Ag, Pt, C
d, Pb, Al, C, Mg, Au, In, Bi, Nb,
Any of Si, Ta, Ti, U, B, Eu, Sn, P and W, or a compound or alloy or a mixture thereof is preferable, and these are used alone or in combination of two or more. As the composite material, a physical composite material such as amalgam can be used.

For example, compounds include oxides, borides, and carbides, and oxides include BaO, SrO, and Ca.
O, Y ₂ O ₅ , Gd ₂ O ₃ , Nd ₂ O ₃ , ThO ₂ , Z
rO ₂ , Fe ₂ O ₃ , ZnO, CuO, Ag ₂ O, La
₂ O ₃ , PtO, PbO, Al ₂ O ₃ , MgO, In ₂
O _3, BiO, NbO, there is such as BeO, also in borides _{is, YB 6, GdB 6, LaB} 5, NdB 6, Ce
_{B 6, EuB 6, PrB 6} , ZrB 2 include, as a further carbide UC, ZrC, TaC, TiC, Nb
C and WC. In addition, brass, bronze,
Phosphor bronze, alloy of Ag and Mg (Mg is 2 to 20 wt.
%), An alloy of Cu and Be (Be is 1 to 10 wt%), an alloy of Ba and Al, and an alloy of Ag and Mg, an alloy of Cu and Be, and an alloy of Ba and Al. Alloys are preferred. The oxide can also be obtained by heating only the metal surface in air or oxidizing it with a chemical.

Still another method is to heat before use,
An oxide layer can be formed on the surface to obtain a stable oxide layer over a long period of time. As an example, an oxide film can be formed on the surface of an alloy of Mg and Ag in water vapor at a temperature of 300 to 400 ° C., and this oxide thin film is stable for a long period of time. These substances are in the form of bulk (solid, plate) and appropriate base material (support)
(Japanese Patent Application Laid-Open No. 3-1088698). For example, it can be added to the surface of or near the surface of the ultraviolet ray transmitting substance (Japanese Patent Publication No. 7-93098). Any method can be used as long as photoelectrons are emitted by irradiation of ultraviolet rays. For example, a method of coating and using on a glass plate, a method of embedding near the surface of a plate material as another example, a method of adding on a plate material and further coating another material on the plate material for use And a method of using a mixture of an ultraviolet-permeable substance and a substance that emits photoelectrons. In addition, a method of adding in a thin film shape, a method of adding in a net shape, a linear shape, a granular shape, an island shape, a belt shape, or the like can be appropriately used.

A method of adding a material that emits photoelectrons can be made by coating or attaching a known material to the surface of an appropriate material. For example, an ion plating method, a sputtering method, an evaporation method, a CVD method, a plating method, a coating method, a stamp printing method, and a screen printing method can be appropriately used. The thickness of the thin film may be a thickness at which photoelectrons are emitted by ultraviolet irradiation, and may be 5 to 5,000, usually 20.
~ 500 ° is common. The shape of the base material used is plate,
There are pleated, cylindrical, rod-like, linear, net-like, fibrous, honeycomb-like shapes and the like, and the shape of the surface can be appropriately made uneven. Further, the tip of the convex portion may be sharp or spherical (Japanese Patent Publication No. 6-74908).

For the addition of the thin film to the base material, one or two or more materials can be used in a single layer or in a multi-layered manner, as already proposed by the present inventors. That is, a plurality of thin films can be used as appropriate (composite) to form a double structure or a multi-layer structure of more than that (Japanese Patent Laid-Open No. 4-152296). The type and addition method of these optimal shapes and materials that emit photoelectrons by irradiation of ultraviolet rays, the thickness of the thin film, the type of device, the scale and shape, the type of photoelectron emitting material, the type of base material, the strength of the electric field described below, Preliminary tests can be performed as appropriate in consideration of how to apply, effect, economy, and the like. When the photoelectron emitting material is used in addition to the base material, the base material may be ceramic, clay, or a well-known metal material in addition to the above-described ultraviolet ray transmitting material. Alternatively, the surface of a light source described below can be coated with the above-mentioned photoelectron emitting material (the light source and the photoelectron emitting material are integrated) (Japanese Patent Laid-Open No. 4-243540).

Generation of photoelectrons by irradiating the photoelectron emitting material with ultraviolet rays is performed by forming an electric field (electric field) between the photoelectron emitting material (negative electrode) and an electrode (positive electrode) described later. It is preferable to carry out under an electric field, since the generation occurs effectively. The method (structure) of forming the electric field can be appropriately selected depending on the shape and structure of the charged portion, the application field, the type of the device, the expected effect (accuracy), and the like. The intensity of the electric field can be determined as appropriate depending on the type of addition to the photoelectron emitting material or the base material, and this is another invention of the present inventors. The electric field strength is generally from 0.1 V / cm
2 kV / cm. The electrode material for the electric field may be any material as long as it does not generate impurities and the like and is a conductive material. The electrode material for the electric field can also be used as a charged particle collecting material described later, and has the same shape and material (eg,
SUS material, Cu-Zn material, W material) can be suitably used.

Next, an irradiation source for emitting photoelectrons from the photoelectron emitting material will be described. The irradiation source can be installed at the center of the box together with the photoelectron emitting material, and emits photoelectrons by irradiating the photoelectron emitting material. The irradiation generates thermal convection inside the box, and the compact. Any one can be used as long as it can be used safely. Irradiation sources include those that emit radiation, lasers, and ultraviolet light. Of these, ultraviolet rays are preferable because they can be used safely and can be made compact. When a photocatalyst is provided, any photocatalyst can be used as long as the photocatalyst exerts a photocatalytic action upon irradiation of the photocatalyst. As such an irradiation source, ultraviolet rays are preferable in terms of simple installation and effects (performance). One of the features of the present invention is that the irradiation of the ultraviolet rays enables charging and collection of particulate matter by photoelectron emission from the photoelectron emitting material, and decomposition and removal of gaseous harmful components by a photocatalyst.

As such an ultraviolet light source, a mercury lamp, a hydrogen discharge tube, a xenon discharge tube, a Lyman discharge tube or the like can be used as appropriate. Examples of the light source include a germicidal lamp, a black light, a fluorescent chemical lamp, a UV-B ultraviolet lamp,
There is a xenon lamp. Among them, a germicidal lamp (wavelength: 2
54 nm) is preferable depending on the field of use because it has a bactericidal (sterilizing) action on suspended fungi and microorganisms coexisting with the particulate matter. That is, by using a germicidal lamp as an ultraviolet light source, fungi and microorganisms collected on the charged particle collecting material can be irradiated with ultraviolet light (main wavelength: 254 nm) from the lamp installed near the collecting material. And sterilized (sterilized). Fungi and microorganisms having high UV resistance (fungi and microorganisms that are difficult to sterilize (sterilize) by irradiation with a germicidal lamp) are collected on the collecting electrode material of the present invention as described above, and a nearby ultraviolet lamp ( (254 nm), sterilization (sterilization) is completed. This is one of the features of the present invention.

Next, the charged particle collecting electrode material will be described. The charged particle collecting electrode material is arranged on the outer periphery of the box, and may be any material that collects particulate matter charged by photoelectrons, and a well-known charged particle collecting electrode material can be used. . For example, a dust collecting plate in a normal charging device,
There are wool-like structures such as dust collection electrodes, various electrode materials, electret materials, steel wool electrodes, and tungsten wool electrodes. The collecting electrode material is provided along the direction in which the air to be processed flows to the left and right of the ultraviolet light in the box. This method of installation effectively collects charged particles (charged particulate matter), which is one of the features of the present invention. The shape of the collecting electrode material includes a plate shape, a pleated shape, a cylindrical shape, a rod shape, a linear shape, a net shape, a fiber shape, and a honeycomb shape.

As described above, the collecting electrode material can also be used as an electric field setting electrode material for photoelectron emission.
The dual use is preferable because the cleaning device can be made compact. Suitable materials, their shapes, and installation methods are appropriately subjected to preliminary tests according to the field of use, device shape, scale, type and shape of irradiation source, method of applying an electric field for photoelectron emission, type of electrode material, required performance, etc. You can decide to do it. Next, the photocatalyst will be described. The photocatalyst is disposed on at least one surface of the photoelectron emitting material, the ultraviolet light source, the charged particle trapping material, and the outer frame or on the irradiation surface to which the ultraviolet light is irradiated, and the photocatalyst exerts a photocatalytic action by the irradiation of the ultraviolet light. However, any material may be used as long as it can decompose and remove gaseous harmful components (harmful gas, odorous gas).

Photocatalysts are generally preferred because semiconductor materials are effective, are readily available, and have good workability.
From the viewpoint of effect and economy, Se, Ge, Si, Ti, Z
n, Cu, Al, Sn, Ga, In, P, As, Sb,
C, Cd, S, Te, Ni, Fe, Co, Ag, Mo,
Any of Sr, W, Cr, Ba, and Pb, or a compound, alloy, or oxide thereof is preferable, and these are used alone or in combination of two or more. For example, the elements are Si, Ge, Se, and the compounds are AlP, A
lAs, GaP, AlSb, GaAs, InP, GaS
b, InAs, InSb, CdS, CdSe, ZnS,
MoS ₂ , WTe ₂ , Cr ₂ Te ₃ , MoTe, Cu ₂
S, WS ₂ , oxides such as TiO ₂ , Bi ₂ O ₃ , C
uO, Cu ₂ O, ZnO, MoO ₃ , InO ₃ , Ag ₂
O, PbO, SrTiO ₃ , BaTiO ₃ , Co
_{There are 3} O ₄ , Fe ₂ O ₃ , NiO and the like.

The photocatalyst may be formed on a suitable base material or the photoelectron emitting material, ultraviolet light source, charged particle collecting material, surface of the outer frame,
Alternatively, it can be appropriately disposed on the surface of a material in the vicinity thereof by a known addition method such as a vapor deposition method, a sputtering method, a sintering method, a sol-gel method, a coating method, and a baking coating method. The shape of the photocatalyst to be distributed is
A thin film, a line, a net, a band, a comb, a grain, an island, or the like can be appropriately selected and used according to a base material described below. That is, the installation position of the photocatalyst may be any position where the ultraviolet ray is irradiated, and the following example will be given. (1) Integration with the photoelectron emission material (Japanese Patent Application No. 8-132)
No. 563), for example, a method of adding a photocatalyst and a substance which emits photoelectrons on an appropriate base material,
A method of adding a photocatalyst onto a material that emits photoelectrons,
There is a method of adding a substance that emits photoelectrons onto a photocatalyst. Such a configuration removes gaseous harmful components (eg, non-methane hydrocarbons) that adhere to the photoelectron emission material, and thus is preferable depending on the application field and the type and shape of the photoelectron emission material.

(2) Integration with the electrode material for electric field (Japanese Patent Application No. 8-231290), or the electrode material for electric field can be used also as the electrode material for charged particle collection. There is integration with the material. For example, a method of adding a photocatalyst in the form of a net or an island to a SUS material (SUS is a positive electrode), a method of adding a photocatalyst in the form of a film to a ceramic, and sandwiching the SUS material with a reticulated SUS material (SUS is a positive electrode). is there. (3) The photocatalyst is made of glass, ceramic,
Add a photocatalyst to the surface of fluororesin, plate-like, net-like,
There is a method of wrapping or sandwiching in an appropriate material such as a fibrous or film-like material. (4) When installing a shielding material, there is a method of adding it to the surface of the shielding material. (5) Coating method on an ultraviolet lamp ((Japanese Patent Application No. 8-3)
No. 1231), etc., and these can be determined by appropriately conducting preliminary tests based on the use destination, the type of the apparatus, the conditions (concentration) of the processing air, the required performance, and the like. Ti or Zn used as the photocatalyst can be used as a photocatalyst by, for example, oxidizing plate-like Ti, and thus can be suitably used depending on the type of the device.

Further, in order to improve the photocatalytic action, a substance such as Pt, Ag, Pd, RuO ₂ or Co ₃ O ₄ can be added to the above photocatalyst. The addition of the substance
It is preferable because the photocatalytic action is promoted. These can be used alone or in combination. Usually, the amount of addition is 0.01 to 10% by weight with respect to the photocatalyst, and an appropriate concentration can be selected by performing a preliminary test as appropriate depending on the type of the added substance and required performance. Well-known means such as an impregnation method, a photoreduction method, a sputter deposition method, and a kneading method can be appropriately used for the addition method. In the present invention, when ultraviolet rays emitted from the cleaning device may adversely affect the outside, a shielding material (light shielding material) is appropriately installed on the device so that the ultraviolet light is not emitted from the device. be able to. When the shielding material is provided, the photoelectron emitting material and / or photocatalyst can be added to the surface of the shielding material.

Next, a box surrounded by an outer frame will be described.
The box body is capable of integrally storing the photoelectron emitting material, an ultraviolet light source, an electric field setting and a charged particle collecting electrode material, and a photoelectron emitting material and an ultraviolet light source are housed in a central portion thereof, A charged particle collecting electrode material is accommodated in an outer peripheral portion thereof, and further, a gas inlet is provided below a central portion of the box, and a gas outlet is provided in an outer peripheral side portion of the box. ing. The shape of the box may be any of a square shape, a rectangular shape, a circular shape, an elliptical shape, and the like, each of which has a planar shape and a side surface shape. . In the present invention, the cleaning device is a box having an outer frame having the above-described configuration because the device irradiates ultraviolet rays in an electric field. Therefore, (a) the electrode material for forming an electric field and a peripheral cover are used. (B) shielding material for avoiding direct irradiation of ultraviolet rays to the space to be cleaned, and
(C) By integrating and covering the apparatus, the space to be cleaned, in particular, the installation / removal to / from the ceiling, and the ease of maintenance management can be improved.

In the present invention, by installing the above-described cleaning device on the ceiling of the space to be cleaned, the air flow naturally convects by heating with the ultraviolet light source, and the processing target flowing from the inflow port at the bottom of the box body. The gas is charged by the photoelectrons emitted from the photoelectron emitting material under ultraviolet irradiation set in the center, and the particles are charged by the charged particle collecting electrode material set in the periphery to be purified. The discharged gas flows out of the outlet provided on the outer peripheral side surface of the box into the space, and the space is cleaned. The enclosed space of the present invention can be similarly cleaned not only in the air but also in other gases such as N ₂ and Ar. Further, the number of the cleaning apparatuses of the present invention installed in the closed space can be selected by conducting a preliminary test as appropriate according to the size of the space, the performance of the cleaning apparatus to be installed, the cleanliness of the space, and the like.

[0028]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples. Example 1 Air cleaning in a liquid crystal glass (substrate) storage (stocker) 1 in a class 1000 clean room liquid crystal factory will be described with reference to FIG. In FIG. 1, air in a substrate storage 1 which is an enclosed space is cleaned by an ultraviolet lamp 2, a photoelectron emitting material 3, a charged particle collecting material (electrode) 4 _-1 , 4 _-2 , which is installed on a ceiling. The present invention is implemented by the air cleaning device A of the present invention including the light shielding material 12 and the box 13. The particulate matter (fine particles) 6 enters the liquid crystal glass storage 1 from the clean room by opening and closing the storage 1, such as taking the substrate storage carrier 9 storing the liquid crystal glass substrate 10 into and out of the storage 1. The particulate matter 6 is charged and collected by the air cleaning device A of the present invention, and the space B to be cleaned in which the substrate 10 is stored becomes an ultra-clean space that is cleaner than class 1.

That is, when the photoelectron emitting material 3 is irradiated with ultraviolet rays from the ultraviolet lamp 2 in a state where an electric field is formed between the photoelectron emitting material 3 and the electrodes 4 _-1 and 4 _-2 , the photoelectrons 5 are emitted from the photo electron emitting material 3. Is done. Here, the fine particles 6 in the liquid crystal glass storage 1 are divided into an ultraviolet lamp 2, a photoelectron emitting material 3, an electrode 4 _-1 ,
4 The charged collector C of the fine particles consisting _-2 charged by photoelectrons 5 described above, next charged particles 7, the charged particles 7 is the collecting electrode 4 _-1, 4 _-2, Among stocker 1 Ultra It is cleaned. The electrodes 4 _-1 and 4 _{-2 also} serve as an electrode material for setting an electric field for effectively emitting the photoelectrons 5 from the photoelectron emitting material 3 and a charged particle collecting material. Here, the photoelectron 5
The charged fine particles 7 charged by the air flow 8c-8
left and right UV lamp 2 along a _(4-1, 4 _-2) to set up the charged particle collecting material 4 _-1, is efficiently collected by 4 _-2. By installing the collecting materials 4 _-1 and 4 _-2 of the charged fine particles 7 on the left and right sides of the ultraviolet lamp 2 along the air flows 8c to 8a, an effective collecting operation with a small pressure loss is performed. This is one of the features of the invention.

8a, 8b and 8c show the flow of air in the storage 1 caused by the rise in the temperature inside the cleaning device A of the present invention by the ultraviolet lamp 2, and the fine particles 6 in the storage 1 It effectively moves to the charging / collecting section C and is charged / collected. The light shielding material 12 is provided to prevent the ultraviolet rays emitted from the ultraviolet lamp 2 from being directly irradiated on the substrate 10. The fine particles 6 are introduced into the cleaning device A of the present invention by the air flow 8c from the lower direction to the upper direction. On the other hand, the photoelectrons 5 that charge the fine particles are generated by the
Further, since the particles are emitted from the upper side to the lower side, the charging efficiency of the fine particles 6 (the efficiency with which the photoelectrons 5 adhere to the fine particles 6 and the fine particles obtain electric charges) increases, which is one of the features of the present invention. When the liquid crystal glass substrate 10 is stored in the storage 1, contamination by the particulate matter 6 is prevented, so that the circuit (pattern) on the substrate is not disconnected or short-circuited, and the yield in product manufacturing is improved. I do. UV lamp 2 of this example
Is a germicidal lamp, the photoelectron emitting material 3 is Cu-Zn plated with Au, and the charged particle collecting materials 4 _-1 and 4 _-2 are SUS materials.

Embodiment 2 Air cleaning in a wafer storage (stocker) 1 in a semiconductor factory of a class 1000 clean room will be described with reference to FIG. In FIG. 2, air cleaning in a wafer storage 1 which is a closed space is performed by an ultraviolet lamp 2, a photo-electron emitting material 3, and a charged particle collecting material (electrode) to which a photocatalyst 14 is added on its surface, which is installed on the ceiling. This is implemented by the air purifying apparatus A of the present invention comprising 4 _-1 , 4 _-2 , the light shielding material 12 and the box 13. In the wafer storage 1, the particulate matter (particulates) 6 and the gaseous harmful component 15 (here) are opened and closed from the clean room by opening and closing the storage 1 such as loading and unloading of the wafer carrier 9 in which the wafer 10 is stored in the storage 1. in, hydrocarbons (e.g., phthalic acid ester) to increase the contact angle of the wafer surface when adhered to the wafer NH ₃ causing or poor resolution (cloudiness)) but enters, the particulate material 6, the present invention The gaseous harmful component 15 is contacted with the photocatalyst 14 which is exerting a photocatalytic action by irradiation of ultraviolet rays from the ultraviolet lamp 2, is decomposed and detoxified, and the wafer 10 is charged. To be cleaned is B
Is an ultra-clean space that is cleaner than class 1 in which gaseous harmful components are detoxified (inert gasification of the wafer 10).

That is, when the photoelectron emission material 3 is irradiated with ultraviolet rays from the ultraviolet lamp 2 in a state where an electric field is formed between the photoelectron emission material 3 and the electrodes 4 _-1 and 4 _-2 , the photoelectrons 5 are emitted from the photoelectron emission material 3. Is done. Here, the fine particles 6 in the wafer storage 1
The above-mentioned photoelectrons 5 are charged in the fine particle charge collecting section C composed of an ultraviolet lamp, a photoelectron emitting material 3 and electrodes 4 _-1 and 4 _-2.
To become charged fine particles 7, and the charged fine particles 7
Are collected by the electrodes 4 _-1 and 4 _-2, and are ultra-cleaned in the wafer storage 1. The electrodes 4 _-1 and 4 _{-2 also} serve as an electrode material for setting an electric field for effectively emitting the photoelectrons 5 from the photoelectron emitting material 3 and a charged particle collecting material for charged particles.

On the other hand, the gaseous harmful component 15 comes into contact with the photocatalyst added to the surfaces of the charged particle trapping materials 4 _-1 and 4 _{-2 and} the surface of the light shielding material 12 by the air flows 8a, 8b and 8c. It is detoxified. Here, the charged fine particles 7 charged by the photoelectrons 5 are charged particle trapping materials 4 _-1 , 4-1 installed on the right and left (4 _-1 , 4 _-2 ) of the ultraviolet lamp 2 along the air flows 8 c to 8 a. the 4 _-2 is efficiently collected. By installing the collecting materials 4 _-1 and 4 _-2 of the charged fine particles 7 on the left and right sides of the ultraviolet lamp 2 along the air flows 8c to 8a, an effective collecting operation with a small pressure loss is performed. One of the features of the invention
One. In addition, the gaseous harmful component 15 also contains the surfaces of the charged particle trapping materials 4 _-1 and 4 _{-2 and} the surface of the light shielding material 12 installed on the left and right (4 _-1 and 4 _-2 ) of the ultraviolet lamp 2 as described above. Since the photocatalyst 14 is efficiently contacted with the photocatalyst 14, the effective treatment with a small pressure loss is performed.

8a, 8b and 8c show the flow of air in the storage 1 caused by the rise in the temperature inside the cleaning device A of the present invention by the ultraviolet lamp 2, and the flow shows the fine particles 6 and the gas in the storage 1. Hazardous component 15 is effectively charged and
It moves to collection part C and is processed. The light-shielding member 12 is provided to prevent the ultraviolet rays emitted from the ultraviolet lamp 2 from being directly irradiated on the wafer 10. The fine particles 6 are separated from the cleaning device A of the present invention by the air flow 8c from below to above.
Will be introduced. On the other hand, photoelectrons 5 that charge microparticles 5
Is emitted from the photoelectron emitting material 3 from above to below, so that the charging efficiency of the microparticles 6 (the efficiency of the photoelectrons 5 adhering to the microparticles 6 and the microparticles getting charged) is increased, and the feature of the present invention. It is one of. The details of the treatment of the gaseous harmful component by the photocatalyst are unknown because the concentration of the gaseous harmful component is extremely low, and the like.

Hydrocarbons (non-methane hydrocarbons, HC)
Depending on the substrate, even a normal concentration in air (eg, general outside air) causes contamination. Various H. Among C, the component that increases the contact angle is considered to differ depending on the type of substrate (wafer, glass material, etc.) and the type and properties of the thin film on the substrate. As a result of intensive studies, the present inventor has found that it is effective to remove non-methane hydrocarbons to an index of 0.2 ppm or less, preferably 0.1 ppm or less by a photocatalytic decomposition treatment using the index as a parameter. That is, what can be said in common with the organic gas (HC) that increases the contact angle of the substrate surface in a normal clean room is that the high molecular weight H.C. C is mainly used, and its structure is -CO, -C
OO bond (having hydrophilicity). This H. C can be considered as a hydrophobic substance having a hydrophilic part (-CO, -COO bonding part) (a part of -C-C- in the basic structure of HC).

[0036] With reference to embodiments, the organic gas to increase the contact angle of the surface of the substrate such as a wafer substrate in a normal clean room, high molecular weight of C ₁₆ -C ₂₀ H. C, for example, a phthalic acid ester and a higher fatty acid phenol derivative. These components have a chemical structure of —CO and —COO bonds (having hydrophilicity) in common.
The cause of these contaminated organic gases is a plasticizer, a release agent, an antioxidant, and the like of the polymer product, and the place where the polymer product exists is a source (see “Air Purification”, Vol. 1
No., p16-21, 1995). The details of the mechanism of treatment of these organic gases by the photocatalyst are unknown, but can be estimated as follows. That is, in these organic gases, the -CO and -COO bond portions are O
A hydrogen bond is formed with the H group, and the upper surface thereof becomes a hydrophobic surface. As a result, the surface of the wafer or glass becomes hydrophobic, the contact angle becomes large, and when the film is formed on the surface, the adhesion of the film is weak.

When a photocatalyst is installed in an atmosphere in which an organic gas is present, first, the organic gas is adsorbed on the surface of the photocatalyst in the same manner as the surface of a wafer or a glass, and then the active portions of the photocatalyst, -CO and -COO bonds, The part is converted to another stable form by irradiation of the photocatalyst with light. As a result, the organic gas is in a stable form, does not adhere to the wafer or the glass substrate, or does not exhibit hydrophobicity even if it adheres. When the wafers 10 are stored in the main storage 1, the particulate matter 6
And contamination by gaseous harmful substances 15 is prevented,
There is no disconnection or short circuit of the circuit (pattern) on the wafer,
Since the contact angle on the wafer surface does not increase (the adhesion of the film formed on the wafer is strong) and no resolution failure occurs, the yield in product manufacturing is improved. UV lamp 2 of this example
Is a germicidal lamp, the photoelectron emitting material 3 is Cu-Zn plated with Au, and the charged particle trapping materials 4 _-1 and 4 _-2 are SUS
Wood, photocatalyst is TiO _2.

Example 3 The air purification in the pass box (transfer device for instruments and the like installed between the outside and the clean room) 1 in the biological clean room of class 10000 is shown in FIG.
This will be described. 3, closed air cleaning of the pass box in 1 is a space, the installed ultraviolet lamp in the ceiling portion (germicidal lamp) 2, a photoelectron emitting material 3, the charged particle collecting material (electrode) 4 _-1, 4 _{- 2.} It is implemented by the air cleaning device A of the present invention comprising the box 13. Each time the instruments 16 carried into the clean room are introduced into the pass box 1, the particulate matter 6 containing fungi and microorganisms enters the pass box 1. The substance 6 is charged and collected by the air cleaning device A of the present invention.
Here, the fungi and microorganisms are the charged particle collecting material 4 of the present invention.
Since they are collected at _-1 and _4-2 , they are irradiated with an ultraviolet lamp (germicidal lamp) 2 in the very vicinity and are completely sterilized (sterilized).

That is, the airborne fungi and microorganisms 6 are first partially killed in the space of the pass box, but surviving fungi and microorganisms, UV-resistant fungi and the like are charged particles of the present invention. Since they are collected by the collecting materials 4 _-1 and 4 _-2 and irradiated with a sterilizing line (254 nm ultraviolet light from a sterilizing lamp),
It is completely sterilized (sterilized). In this way, instruments 1
The to-be-cleaned space B where 6 is placed becomes an ultra-clean space from which airborne fungi, microorganisms and fine particles 6 have been removed. That is, when the photoelectron emission material 3 is irradiated with ultraviolet rays from the ultraviolet lamp 2 in a state where an electric field is formed between the photoelectron emission material 3 and the electrodes 4 _-1 and 4 _-2 , the photoelectrons 5 are emitted from the photoelectron emission material 3. Here, the particulate matter 6 containing fungi and microorganisms in the pass box 1 contains the ultraviolet lamp 2, the photoelectron emitting material 3, the electrode 4 _-1 ,
4 The charged collector C of the particulate matter consisting _-2 charged by photoelectrons 5 described above, the charged particulate matter 7, and the
The particulate matter 7 is collected by the electrodes 4 _-1 and 4 _-2, and is ultra-cleaned in the pass box 1.

The electrodes 4 _-1 and _{4-2 also} serve as an electrode material for setting an electric field for effectively emitting the photoelectrons 5 from the photoelectron emitting material 3 and a charged particle collecting material. Here, the charged fine particles 7 charged by the photoelectrons 5 form the air flows 8c to 8c.
The charged particle collecting materials 4 _-1 and 4 _-2 installed on the left and right sides (4 _-1 and 4 _-2 ) of the ultraviolet lamp 2 along 8a efficiently collect the particles. By installing the collecting materials 4 _-1 and 4 _-2 of the charged fine particles 7 on the left and right sides of the ultraviolet lamp 2 along the air flows 8 c to 8 a, effective collection with a small pressure loss is performed.
This is one of the features of the present invention. 8a, 8b and 8c show the flow of air in the pass box 1 caused by the rise in the temperature inside the cleaning device A of the present invention by the ultraviolet lamp 2, and the flow contains particles containing fungi and microorganisms in the pass box 1. The substance 6 effectively moves to the charging / collecting section C and is charged / collected.

The particulate matter 6 containing fungi and microorganisms is directed to the cleaning device A of the present invention by the air flow 8c from the downward direction to the upward direction. On the way, the sterilizing line (254 nm) from the sterilizing lamp is passed. And is efficiently sterilized (sterilized) by being irradiated with ultraviolet rays. On the other hand, surviving fungi, microorganisms, etc. (particulate matter) are charged from the photoelectron emitting material 3 from above to below because the photoelectrons 5 that charge the particulate matter are discharged from above. Efficiency (the efficiency at which the photoelectrons 5 adhere to the particulate matter 6 and the particulate matter obtains electric charges) increases, which is one of the features of the present invention. When instruments (eg, surgical instruments) 16 are introduced into a clean room using the present pass box 1, contamination of the instruments 16 from fungi and microorganisms is prevented.

Embodiment 4 FIGS. 4 to 7 show an air purifying apparatus A having another structure in Embodiments 1 to 3. FIG. FIG. 4 is characterized in that a reticulated photoelectron emitting material 3 is used. FIG. 5 shows the surface of the photoelectron emission material 3 and the charged particle trapping materials 4 _-1 and 4 _{-2 in} the air cleaning device A of FIG.
The photocatalyst 14 is added to the surface. FIG. 6 is characterized in that mesh electrodes (charged particle collecting material) 4 _-1 and 4 _-2 are used. The air cleaning device A of FIG. 6 is particularly preferable for collecting and removing airborne fungi and microorganisms. FIG. 7 shows that the surface of an ultraviolet lamp 2 is covered with a photoelectron emitting material 3, and an electrode _4-3 for photoelectron emission and charged particle trapping materials _4-1 , _4-2 are separately provided. There is a feature. 4 to 7, the same reference numerals as those in FIGS.

Example 5 The following sample air was put into a storage having the structure shown in FIG. 1 and ultraviolet irradiation and application of voltage to the electrodes were performed. The charged particle trapping material was set on the left and right sides of the ultraviolet lamp. (Of the present invention), when installed only on the right side (for comparison)
Using a particle analyzer, the concentration of the particles in the storage and the number of particles adhering to the wafer were examined using a wafer / dust detector. Storage size; 80 liters Air purifier; Photoelectron emission material, UV lamp, charged particle collection material (electrode material) and light shielding material as shown in Fig. 1 and installed in the center of the ceiling of the storage room. (1) Photoemission material: Cu-Zn plated with Au. (2) UV lamp: sterilizing lamp (10 W). (3) Charged particle collecting material: Material SUS, electric field 200V /
cm. (4) Light shielding material: SUS material. Sample air; semiconductor factory (class 1,00
0) Clean room air. Wafer: 5 inch wafer Particle analyzer: Particle counter, light scattering type,> 0.1 μm

Results The results are shown in FIG. In FIG. 8, the sample of the present invention is −〇−, for comparison, − △ − in which the charged particle trapping material is provided only on the right side of the ultraviolet lamp, and − ● − in which irradiation with the ultraviolet lamp is not performed (blank). Indicated by The arrow (↓) in FIG. 8 indicates non-detection (class 1). Table 1 shows the number of fine particles on the wafer. The number of fine particles indicates the number (class) of particles having a particle size of 0.1 μm or more in 1 ft ³ .

[Table 1]

Example 6 The following sample air was put into a sterilizing clean box having the structure shown in FIG. 3, and ultraviolet irradiation and application of voltage to the electrodes were performed.
When the charged particle collecting material is installed on the left and right sides of the ultraviolet lamp (of the present invention) or only on the right side (for comparison), sterilization (sterilization) of airborne bacteria and microorganisms in the air and The effect of removing fine particles was examined. Clean box size; 80 liters Air purifier; The following photoelectron emission material, ultraviolet lamp, and charged particle collecting material (electrode material) are configured as shown in Fig. 3 and installed in the center of the ceiling of the storage room. (1) Photoemission material: Cu-Zn plated with Au. (2) UV lamp: sterilizing lamp (10 W). (3) Charged particle collecting material: Material SUS, electric field 200V /
cm.

Sample air: air in a clean room (class 10,000) in a hospital. Measurement of bactericidal effect; air in sterilized clean box was expelled using N ₂ gas packed in a high-pressure container passed through an ULPA filter, and the expelled gas was sprayed on an agar medium, and the number of colonies after culturing at 30 ° C for 72 hours was observed. did. Measurement of concentration of fine particles: The concentration of fine particles in the gas expelled in the same manner as above was measured using a particle counter (light scattering type,> 0.1 μm).

Results The results are shown in Table 2 (number of colonies) and Table 3 (concentration of fine particles). The results show the values measured five times.

[Table 2]

[0048]

[Table 2]

[0049]

According to the present invention, the following effects can be obtained. 1) In a cleaning method of a space in which photoelectrons are emitted from a photoelectron emitting material by irradiation of ultraviolet rays, charges are given to particulate matter in a closed space by the photoelectrons, and charged and collected, a photoelectron emitting material is provided on a ceiling surface of the space; By installing an ultraviolet light source and charged particle collecting materials (electrodes) on the left, right and surroundings, and integrating and storing (unitized) in a box surrounded by an outer frame, (a) charged by photoelectrons The particulate matter is efficiently trapped by the charged particle collecting material installed on the left, right, and around the irradiation source because the air flow generated by the irradiation from the irradiation source occurs uniformly on the left, right, and around the irradiation source. Gathered,
The space is effectively cleaned. (B) By being integrated in the box, handling (removal, installation, maintenance and management) is facilitated. Safety has also improved. (C) and (b) can be easily attached to an existing space (cleaned space), so that the use has been expanded. (D) The work area on the floor can be used over the entire surface because the work area may be attached to the ceiling (the effective work area is increased). (E) The use of the box has been expanded because it can also serve as a shielding material depending on the use.

2) In the unit, by adding (coating) a photocatalyst to a position irradiated with ultraviolet rays, gaseous harmful components coexisting with the particulate matter are simultaneously treated. That is, simultaneous removal of particles and gas can be easily performed, and the use has been expanded. 3) By using a germicidal lamp as an ultraviolet light source in the unit, (a) sterilization in a floating state of airborne fungi and microorganisms is performed by:
Although it is completely difficult depending on the type of the fungus or microorganism,
According to the present invention, bacteria and microorganisms are charged and collected, and irradiation with a germicidal line from a germicidal lamp in the vicinity of the collecting material is performed for a long period of time. Therefore, the bactericidal (sterilizing) effect is complete and safety is improved. In addition, since there is no fear of multiplication, the device can be used with confidence. For example, molds such as black spores are highly resistant to UV and are difficult to completely sterilize in a normal airborne state, but as described above, effective sterilization can be performed in the present invention. (B) In the above, since the fine particles can be removed at the same time, a sterile and dust-free space from which fungi and microorganisms have been removed (a sterile ultra-clean space that is cleaner than class 1) has been effectively created.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram in which a cleaning device of the present invention is used for a liquid crystal glass storage.

FIG. 2 is a schematic configuration diagram in which another cleaning apparatus of the present invention is used for a wafer storage.

FIG. 3 is a schematic configuration diagram in which a cleaning device according to the present invention is used for a pass box.

FIG. 4 is a schematic configuration diagram showing an example of a cleaning device of the present invention.

FIG. 5 is a schematic configuration diagram showing an example of a cleaning device of the present invention.

FIG. 6 is a schematic configuration diagram showing an example of a cleaning device of the present invention.

FIG. 7 is a schematic configuration diagram showing an example of the cleaning device of the present invention.

FIG. 8 is a graph showing the change in the number of fine particles (ft ³ ) depending on the retention time (h) showing the results of the present invention.

FIG. 9 is a schematic configuration diagram of a wafer storage using a known cleaning device.

[Explanation of symbols]

1: enclosed space, 2: ultraviolet lamp, 3: photoemission material,
4 _-1 , 4 _-2 , 4 _-3 : charged particle collecting material (electrode), 5: photoelectron, 6: fine particle, 7: charged fine particle, 8: air flow,
9: storage carrier, 10: substrate (glass, wafer), 1
1: reflective surface, 12: light shielding material, 13: box, 14: photocatalyst, 15: gaseous harmful component, 16: instruments, A: air cleaning device, B: space to be cleaned, C: charge collection unit

Claims (5)

[Claims] 1. A gas cleaning apparatus comprising an ultraviolet light source, a photoelectron emitting material, and an electrode material for setting an electric field and collecting charged particles, comprising a box surrounded by an outer frame. An ultraviolet light source and a photoelectron emitting material are provided at the center, and the electrode material is provided and integrated at the outer periphery thereof, and a gas inflow port is provided below the center of the box body. A gas purifier having an outlet. 2. The gas cleaning apparatus according to claim 1, wherein a photocatalyst is disposed on an irradiation surface of the box body to be irradiated with ultraviolet rays. 3. The gas cleaning apparatus according to claim 1, wherein the collecting electrode material is provided along a gas flow toward an outlet. 4. A method for purifying gas in an enclosed space, wherein the gas purifying device according to claim 1, 2 or 3 is installed on a ceiling of the enclosed space with the gas inlet directed downward. And passing the gas in the enclosed space through the device. 5. A closed space, wherein the gas purifying apparatus according to claim 1, 2 or 3, is installed in a ceiling with a gas inlet directed downward.