JPH0889746A - Method and device for cleaning gas - Google Patents

Abstract

PURPOSE: To rapidly and effectively obtain a superclean space capable of preventing an increase of a contact angle by installing a stage for removing the harmful components to increase the contact angle and a stage for removing particulates in the hermetic space and placing a heating source in the hermetic space. CONSTITUTION: This cleaning method for preventing the increase in the contact angle of the surfaces of base materials or substrates includes a harmful component removing section A formed by using at least one kinds selected from active carbon, diatomaceous earth, silica gels 2, synthetic zeolite, high-polymer compds., glass materials or fluororesins for removing the harmful components 10 in gases within the hermetic space. Further, a particulate removing section B having a UV ray source 4 or radiation source and photon releasing materials 5 for releasing photons by irradiation with this ray source, electrodes 6 for electric fields and charge particulate capturing materials 7 for removing the particulates 11 in the gases is installed in the hermetic space. Further, a heat generating source 12 for generating gas circulating flow is installed in the hermetic space.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to cleaning gas,
In particular, the present invention relates to a method and apparatus for cleaning gas, which is effective in preventing an increase in contact angle in a closed space. The following are examples of fields to which the present invention can be applied. (1) Prevention of increase in wafer contact angle in semiconductor factories. (2) Prevent increase of contact angle of glass substrate in LCD factory. (3) Preventing the increase of the contact angle of the board in the precision machinery factory. INDUSTRIAL APPLICABILITY The gas cleaning method and apparatus of the present invention can be used for treating air and nitrogen gas and other gases in a clean space such as a valuables storage (stocker), wafer storage, liquid crystal storage, and clean box.

[0002]

2. Description of the Related Art Conventional techniques will be described by taking air cleaning in a clean room in the semiconductor industry as an example. The air cleaning methods in the conventional clean room or the apparatus therefor are roughly classified into (1) a mechanical filtration method (for example, a HEPA filter) (2) filtration by a high voltage charged and conductive filter that electrostatically collects fine particles. Method (for example, HESA filter) (3) Method of charging fine particles by photoelectrons and collecting / removing the fine particles (JP-B-3-5859, JP-A-4-1-1)
No. 71061). All of these methods are aimed at removing fine particles (particulate matter), and include hydrocarbons (HC), SOx, and NO.
There is a drawback that it is ineffective in removing gaseous pollutants (poisonous gases), which increases the contact angle such as x, HCl, NH ₃ .

H. 3 which is a gaseous pollutant (hazardous component).
C. As a method for removing methane, combustion decomposition method, catalytic decomposition method, O ₃
The decomposition method and the like are known. However, these methods have a very low H.V. concentration in the air introduced into the clean room. C.
It has no effect on removal. In addition, H. C. Other harmful components include SOx, NOx, HCl, NH _3, etc.,
As a method for removing these, a method based on a neutralization reaction or an oxidation reaction using an appropriate alkaline substance or acidic substance is known. However, these methods are less effective when the component concentration is an extremely low concentration such as contained in the air introduced into the clean room. In a clean room, H.O. C.
Also poses a problem as a pollutant. Further, various solvents (for example, alcohols, ketones, etc.) generated in the work in the clean room also pose a problem as contaminants.

Further, fine particles and gaseous pollutants (hazardous components)
Substances such as mist and clusters, which are intermediates of, could not be removed by conventional filters. The contaminants in the clean room (particulate matter and gaseous harmful components that increase the contact angle) reduce the productivity (yield) of semiconductor products, that is, the contaminants on the surface of wafers, semi-finished products and substrate of products. Since it will be damaged by deposition, a space that can remove these or prevent contamination is needed. On the other hand, the present inventors have already proposed some proposals for preventing the increase of the contact angle (for example, JP-A-5-1572).
No. 84, JP-A-6-324). In practical use, it was necessary to improve them so that they could be carried out more effectively depending on the application.

[0005]

Problems such as adhesion of harmful components that increase the contact angle to wafers, semi-finished products and products of substrates,
If the fine particles adhere, the productivity of the product will decrease. For example,
In the process of producing a high-performance product from a substrate such as a wafer or glass, it is necessary to temporarily stock (store) for about 1 to 10 days in the work process. In this case, raw materials, semi-finished products,
Since the product is exposed to clean room air, it is contaminated (for example, the contact angle is increased), which causes a decrease in productivity. The contact angle is an index showing the degree of contamination of the surface, and is represented by "an angle showing the wettability of the surface". When the contact angle is high, it is contaminated, and conversely, it is not contaminated. For example, when the wafer comes into contact with the air in a normal clean room, the H.V. C. Adheres to and contaminates the wafer. In this case, the contact angle of the wafer is high.

In order to improve the productivity of products, it is necessary to eliminate both the adhesion of harmful components on the substrate and the adhesion of fine particles to the substrate, which are expressed by the contact angle. That is, in order to improve the productivity of semiconductor products, a gas that is effective in preventing an increase in contact angle and that is dust-free is required, and a method and apparatus therefor are required. Therefore, it is an object of the present invention to provide an air cleaning method and device that responds to the above-mentioned demand and obtains an ultra-clean closed space that is effective in preventing an increase in contact angle.

[0007]

In order to solve the above problems, in the present invention, in a gas cleaning method for preventing an increase in the contact angle of a substrate or a substrate surface, a harmful component and fine particles are contained in a closed space. The gas is passed through a step of removing harmful components in the gas that increases the contact angle and a step of removing fine particles in the gas by photoelectrons by a gas flow based on a heat source provided in the closed space. Is. Further, in the present invention, in a gas cleaning device for preventing an increase in the contact angle of the substrate or substrate surface, in a closed space, for removing harmful components in the gas, activated carbon, diatomaceous earth, silica gel, synthetic zeolite, A harmful gas removing part using at least one adsorbent selected from a polymer compound, a glass material or a fluororesin, an ultraviolet ray source and / or a radiation source for removing fine particles in the gas, and the radiation source. It is provided with a photoelectron emitting material that emits photoelectrons upon irradiation with a magnetic field, a fine particle removing section having an electric field electrode and a charged fine particle collecting material, and a heat source for generating a gas circulation flow in the closed space.

Next, each structure of the present invention will be described in detail. In order to remove the gaseous harmful components (gas and / or mist-like substance) that increase the contact angle, a material that adsorbs and / or absorbs these components that increase the contact angle is used. Non-methane hydrocarbons cause pollution at concentrations in normal air (indoor and outdoor air). Among various non-methane hydrocarbons, the component that increases the contact angle is considered to differ depending on the type of base material (wafer, glass material, etc.) and the type and properties of the thin film on the substrate. As a result of diligent studies, the present inventor has determined that this is 0.2 p
It has been found to be effective to remove pm or less, preferably 0.1 ppm or less. That is, any material that adsorbs and collects non-methane hydrocarbons can be used.
As the adsorbent, activated carbon, diatomaceous earth, silica gel, synthetic zeolite, molecular sieve, polymer compound (for example,
A styrene polymer, a styrene-divinylbenzene copolymer), glass, a fluorine compound, a metal, an ion exchanger (eg, an ion exchange substance), etc. are used.

As the glass material, oxide glass materials such as silicate glass and phosphate glass are generally used. Borosilicate glass (main component: N ₂ O—B ₂ O ₃ —SiO ₂ ) is particularly preferable as the silicate glass because it is easy to mold, has a high adsorption effect, and is inexpensive. Further, when the glass surface is coated with a metal thin film of Ti, Au, Al, Cr or the like, the adsorption effect is enhanced. Examples of the fluorine compound include tetrafluororesin, tetra-hexafluororesin, tetrafluoroethylene resin (PTFE), PFA resin, trifluoroethylene resin, tetrafluoroethylene-ethylene copolymer,
Examples thereof include vinylidene fluoride resin (PVDF), vinyl fluoride resin, graphite fluoride, and Teflon.

The shapes of glass and fluorine compounds used are filter, fiber, mesh, sphere, pellet, lattice,
It can be rod-shaped or pleated. In general, a filter shape is preferable because it has a large adsorption effect. As an example of a molding method in the case of using in a filter shape, there is a method of using a fluorine compound resin as a binder and solidifying a fibrous glass material in a filter shape. When used in such a filter form, C. Since the dust removal performance is added to the removal performance of, the filter configuration becomes simple. Therefore, it is preferable to incorporate such an adsorbent in a pollution control device depending on the field of use, the scale of the device, and the shape of the device. As such an example, there is one in which fibrous borosilicate glass is hardened with PTFE and processed into a filter shape, or one in which fibrous borosilicate glass is hardened with PVDF and processed into a filter shape. By making a filter like this,
H. C. In addition to removal, dust removal (effective for particles having a relatively large particle size) is also added, which is preferable.

Examples of metals include Fe, Ag, Ni,
There are Cr, Ti, Au, Pt, and TiO _2, which are powdery, plate-like, sponge-like, linear, fibrous, or added to an appropriate carrier, for example, silica-alumina gel loaded with Ag or phosphorus. A shape in which zirconate is supported with Ag can be preferably used. Further, as the ion exchanger, those having excellent air permeability are preferable, and fibrous ones are particularly preferable. The ion exchange fiber is an invention already proposed by the present inventors (for example, Japanese Patent Publication No. 5-67325, Japanese Patent Publication No. 6).
-24626), these can be used as appropriate.

In a normal clean room, among the above adsorbents, activated carbon, diatomaceous earth, silica gel, synthetic zeolite, polymer compounds, glass, fluorine compounds and metals are more preferable because of their high adsorption effect. These adsorbents can be effectively used by appropriately combining two or more kinds (Japanese Patent Application No. 5-145073 and Japanese Patent Application Laid-Open No. 6-32).
(See Japanese Patent Publication No. 4). As will be described later, H.264 that is involved in increasing the contact angle. C. Since it is considered that there are a plurality of types of adsorbents, the life of the adsorbents becomes longer when two or more types of adsorbents are used in combination. Cause of pollution H. C. According to the research conducted by the inventors, the H. C. Is mainly a C ₁₆ -C ₂₆ high molecular weight fatty acid, a phthalate ester, and a phenol derivative, which has a hydrophilic group and a hydrophobic group. C. Is. Therefore, usually 1
Depending on the type of adsorbent collected, all H. C. Since there is a limit to the collection of adsorbents, it is considered effective to use adsorbents having different adsorption characteristics by conducting experiments and appropriately combining them.

Further, depending on the type of glass or wafer substrate, or the surface condition of the substrate, H. C. Since the degree of influence of the adsorbent is different, a suitable preliminary test is performed according to the field of use, scale of the equipment, shape, usage conditions of the equipment, shared gas, required performance, economic efficiency, etc., and a suitable one is selected from the above adsorbents. be able to. Depending on the field of application and the type of device, if the air to be treated is dehydrated, dehumidified or dehumidified before air is passed through the adsorbent, the adsorbing performance of the adsorbent is improved and the service life is extended. Therefore, well-known materials such as an adsorption type, an absorption type, and a membrane separation type can be installed in front of the present adsorbent. Among the above-mentioned adsorbents, hygroscopic materials such as silica gel and synthetic zeolite are dehydrated and H. C. It is preferable because it has both functions of removal.

H. C. The absorber is a low concentration H. C. Any substance that reacts with and can be immobilized can be used. Generally, a reaction with Cr ⁶⁺ in the coexistence of H ₂ SO ₄ or a reaction with I ₂ O ₅ in the coexistence of H ₂ S ₂ O ₇ can be used. The former is a low molecular weight H. C. The latter has a high molecular weight H. C. Is effective against. For example, glass beads or an appropriate shape (for example, pellet shape) of a carrier such as zeolite or alumina on the surface of H ₂ SO ₄ acid 6
It is used by being impregnated with an aqueous salt solution containing valent chromium. The term "absorption" means that the reaction is absorbed by a chemical reaction. The absorbent material and / or the usage conditions of the absorbent material can be determined by conducting a preliminary test as appropriate according to the application field of the device of the present invention, device scale, shape, required performance, and the like. The space velocity (SV) of the air to be treated in the apparatus is usually 100 to 200,000 (h
^-1 ), preferably 100 to 30,000 (h ^-1 ).

The above is the description of the embodiment of the present invention in the case of removing the extremely low concentration HC in normal air. Generally, substances that contaminate the substrate or substrate surface and increase the contact angle are (1) SOx, NOx, HCl, NH ₃
As a result of examination by the present inventor, it can be roughly divided into harmful gases such as (2) fine particles, (3) HC, and in normal air (atmosphere in a normal clean room), a semiconductor manufacturing plant, or liquid crystal manufacturing. N used in clean rooms such as factories
_{In 2} , the influence of fine particles and HC on the contact angle is large. That is, generally SOx, NOx, HCl, NH ₃
Has little effect on increasing the contact angle at normal concentration levels in air. Therefore, the effect is obtained by removing dust and HC.

However, SOx, HF, HCl, NOx,
If harmful gases such as NH ₃ are generated in or around the clean room and their concentration is high, they are affected by these gas components, and even if these concentrations are so low that they do not usually affect the base material. Or when the substrate is sensitive or when the surface is in a special state (for example, when the surface of the base material is coated with a special thin film), it may be affected.
In such a case, a method (apparatus) proposed by the present inventor to irradiate harmful gas with ultraviolet rays and / or radiation to atomize the gas and collect the particles (Japanese Patent Application No. 3-2).
No. 2686) is preferably used in combination.
In such a case, another known harmful gas removing material such as activated carbon or ion exchange fiber may be appropriately combined and used. Activated carbon is impregnated with acid or alkali,
It is possible to use those appropriately modified by a known method. Further, also for the purpose of removing HC, a method which has been already proposed by the present inventor to collect the fine particles of HC by irradiation with ultraviolet rays and / or radiation (Japanese Patent Application No. 3-105).
No. 092) can also be used together.

The ion-exchange fiber (filter) is practically preferable because it can simultaneously collect coexisting acidic gas, alkaline gas, odorous gas and the like. The type, amount and ratio of the anion exchange filter and / or cation exchange filter to be used can be appropriately determined according to the types and concentrations of the acidic gas, alkaline gas and odorous gas entrained in the gas. For example, anion exchange filters are effective at collecting acidic gases, and cation exchange filters are effective at collecting alkaline gases such as ammonia. The amount and ratio of the filter used correspond to the concentration and concentration ratio of the substances to be collected, and the amount corresponding to these should be taken into consideration in consideration of the application field, shape, structure, effect, economical efficiency, etc. of the device. It may be decided as appropriate. The kind of the adsorbent and / or the adsorbent used and the use conditions can be appropriately determined. In other words, these should be appropriately preliminarily tested in terms of concentration, type, applicable equipment type, structure, scale, required performance / efficiency, economic efficiency, etc. of clean room contaminants (gaseous and / or mist-like harmful components). I can decide.

Next, the fine particle removing section will be described. Here, it is particularly effective for removing fine particles (ultrafine particles). The fine particle removing unit mainly includes a photoelectron emitting material that emits photoelectrons, which is a feature of the present invention, an ultraviolet ray source and / or a radiation source, an electrode material for electric field, and a charged fine particle collecting material. Each configuration will be described in detail. The photoelectron emitting material may be any as long as it emits photoelectrons by irradiation with ultraviolet rays or radiation, and the smaller the photoelectric work function is, the more preferable. From the viewpoint of effect and economy, Ba, Sr, Ca, Y, Gd, L
a, Ce, Nd, Th, Pr, Be, Zr, Fe, N
i, Zn, Cu, Ag, Pt, Cd, Pb, Al, C,
Mg, Au, In, Bi, Nb, Si, Ti, Ta,
Any one of U, B, Eu, Sn, P, W or a compound, alloy or mixture thereof is preferable, and these are used alone or in combination of two or more kinds. As the composite material, a physical composite material such as amalgam can also 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
There are O ₃ , BiO, NbO, BeO, etc., and boride includes YB ₆ , GdB ₆ , LaB ₅ , NdB ₆ , CeB.
₆ , BuB ₆ , PrB ₆ , ZrB _{2 and the} like, and as carbides, UC, ZrC, TaC, TiC, Nb.
C, WC, etc. In addition, as the alloy, brass, bronze,
Phosphor bronze, an alloy of Ag and Mg (Mg is 2 to 20 wt.
%), An alloy of Cu and Be (Be is 1 to 10 wt%) and an alloy of Ba and Al can be used. Alloys are preferred. The oxide can also be obtained by heating only the metal surface in air, or by oxidizing 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 for a long period of time. As an example of this, an alloy of Mg and Ag can form an oxide film on its surface in water vapor at a temperature of 300 to 400 ° C., and this oxide thin film is stable for a long period of time. In addition, the present inventor
As already proposed, a photoelectron emitting material having a multiple structure can also be suitably used (Japanese Patent Application No. 1-155857).
Also, a substance capable of emitting photoelectrons in a thin film form may be added to an appropriate base material and used (Japanese Patent Application No. 2-278).
123). As an example of this, an ultraviolet transparent substance (base material)
As a substance capable of emitting photoelectrons on the quartz glass as described above, there is a substance in which Au is added in a thin film shape (Japanese Patent Application No. 2-2.
95423).

The shapes of these materials used are rod-shaped, cotton-shaped,
It may have any shape such as a lattice shape, a plate shape, a pleated shape, a curved surface shape, and a wire mesh shape, but a shape having a large irradiation area of ultraviolet rays and a large contact area with the processing air is preferable, and depending on the apparatus, a space to be processed (see below). It is preferable that the fine particles present in (1) can be rapidly moved to the photoelectron emitting portion. The irradiation source for emitting photoelectrons from the photoelectron emitting material may be any one as long as it emits photoelectrons by irradiation. In addition to ultraviolet rays, electromagnetic waves, lasers, and radiations can be appropriately selected and used according to application fields, device scales, shapes, effects and the like. In terms of internal effects and operability,
UV or radiation is usually preferred.

Any kind of ultraviolet light may be used as long as the photoelectron emitting material can emit photoelectrons by its irradiation.
Depending on the field of application, those having a sterilizing effect are preferable. The type of ultraviolet rays can be appropriately determined depending on the application field, work content, application, economic efficiency and the like. For example, in the biological field, it is preferable to use deep ultraviolet rays together from the viewpoint of bactericidal action and efficiency. As the ultraviolet ray source, any one can be used as long as it emits ultraviolet rays,
It can be appropriately selected and used depending on the application field, the shape of the device, the structure, the effect, the economical efficiency and the like. For example, a mercury lamp, a hydrogen discharge tube, a xenon discharge tube, a Lyman discharge tube, or the like can be used as appropriate. In the biological field, sterilization wavelength 2
It is preferable to use an ultraviolet ray having a wavelength of 54 nm because the sterilizing effect can be used together.

Next, the positions and shapes of the photoelectron emitting material and the electric field electrode will be described. The photoelectron emission material and / or the electrode is installed in a part of a space at an appropriate position in the space where the particles are present so that an electric field can be formed between the electric field and the photoelectron emission material, and the photoelectron emission material (-) and the electrode An electric field (electric field) is formed between (+). Due to the electric field, photoelectrons are efficiently emitted from the photoelectron emitting material (photoelectron emitting portion). The position or shape of the electrode or the photoelectron emitting material can be appropriately selected depending on the space in which the particles are present, and if the applied voltage for the electric field can be lowered and the photoelectrons from the photoelectron emitting material can charge the particles in the space. Any of them may be used, and can be appropriately determined by a preliminary test or the like in consideration of the field of use, device scale, shape, effect, economy, and the like. Any material can be used for the electrode material as long as it is a conductor, and various electrode materials in known charging devices can be preferably used.

The inventor has already proposed the installation position and shape of the electrode and the photoelectron emitting material (Japanese Patent Application No. 3-1316).
No. 40) is preferable. The electric field voltage used in the present invention is 0.1 V / cm to 2 kV / cm. The suitable electric field strength depends on the field of application, conditions, device shape, scale,
Preliminary tests and examinations can be made to determine the effect and economy. As the collecting material (dust collecting material) for the charged fine particles, any material can be used as long as it can collect the charged fine particles.
Various electrode materials such as a dust collecting plate and a dust collecting electrode in an ordinary charging device and an electrostatic filter method are generally used, but a wool-like structure in which the collecting portion itself such as a steel wool electrode or a tungsten wool electrode constitutes an electrode. Are also valid.
Electret materials can also be preferably used.

In the use for cleaning a closed space in which gas flow is relatively small as in the present invention, it is preferable that the electrode material for the electric field also serves as or is integrated with the material for collecting charged fine particles because the apparatus can be made compact. For example, among the above-mentioned charged particulate matter collecting materials, various electrode materials such as a dust collecting plate, a dust collecting electrode, or a wool-like electrode material such as a steel wool electrode and a tungsten wool electrode are used as an electric field electrode and a collection of charged particulate matter. It is preferable because it can be combined with the above. In the case of removing particulates by the conventional filter method, it is necessary to fluidize the gas, and there is a problem that the fluidization causes contamination by particulates to spread. On the other hand, the present photoelectron charging / collecting method is effective because all the particulate matter to which the photoelectrons are charged can be collected / removed without positively fluidizing the gas.

Next, the heat source for forming the gas flow in the present invention will be described. Is the heat source due to heating,
Alternatively, the temperature difference between heating and cooling is used. As for the heating source, in normal operation, only the UV lamp is enough, but when performing immediately after opening / closing the door or in a clean room with severe pollution, use a heater that assists the UV lamp as the heating source to circulate. It is preferable because the ultra-clean space can be effectively obtained in a shorter time because the amount of water increases.
The heating source is installed by installing the heating source at an appropriate position in the lower part of the closed space. Normally, when the heating source is installed in the part for removing fine particles or the harmful gas, the part in the space is installed. It is preferable because the circulation of gas becomes effective. Well-known means can be used for the auxiliary heating source used with the ultraviolet lamp, and examples thereof include a heater (heat transfer coil, hot water) and an infrared lamp. Of course, in the present invention, it suffices that heat convection is generated, and therefore it does not prevent cooling of an appropriate position above the sealed space.

The temperature difference between heating and cooling can be determined by carrying out preliminary tests as appropriate depending on the field of use, apparatus shape, structure, size, required performance and the like. Usually, the temperature difference is effective at 3 ° C. or higher, and if it is about 3 ° C. to 10 ° C., it can be set by selecting the type, output, quantity, etc. of the ultraviolet lamps for photoelectron emission. As the temperature difference increases, the circulation flow increases and it is effective, so in addition to the ultraviolet lamp appropriately,
The above-mentioned auxiliary heating source can be used depending on the field, device shape, size, structure, material, medium gas type, required performance and the like. Usually the temperature difference is 3 to 30 ° C. The type of heating source used and the position of the heating source installation are used fields, device shape, structure, material, required performance, type of ultraviolet lamp used, output,
Preliminary tests can be appropriately performed and determined according to the quantity, type of medium gas, etc.

In the present invention, the gas existing in the closed space is not limited to the kind of the medium gas, and other gases such as nitrogen and argon can be used in the same manner as air. In addition,
The positions of the harmful gas removing unit and the fine particle removing unit in the present invention are not limited at all, and for example, the harmful gas removing unit may be installed below the device. Further, not only one place but also a plurality of places can be installed above and below. The clean space thus obtained has the effect of preventing an increase in the contact angle of the glass or wafer substrate or substrate, and this effect is to maintain the adhesive force of the film when the film is formed on the substrate or substrate. It is of high practical value because it is effective.

[0029]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. Example 1 Air cleaning in a wafer storage of a semiconductor factory will be described with reference to the basic configuration diagram of the present invention shown in FIG. The wafer storage 1 is installed in a class 10,000 clean room. The air cleaning of the wafer storage 1 which is a closed space is performed by filling the silica gel 2 which is an adsorbent which is installed on one side of the wafer storage 1 and which adsorbs a harmful gas which increases the contact angle, and the glass fiber filter 3 which is a fluororesin binder. Component removal part A consisting of parts, an ultraviolet lamp 4, a photoelectron emission material 5, an electrode 6 for setting an electric field, and a collection material 6 for charged fine particles
(In this configuration, the electrode also serves as a trapping material) and the fine particle removing unit B including the trapping material 7 for the leak-charged fine particles.

In the storage case 1, the harmful gas 10 which increases the contact angle of the surface of the wafer 9 from the outside of the storage case by opening and closing the wafer case 8 by opening and closing the door (not shown) of the storage case.
(Here, it is mainly considered to be H.C.) and the fine particles 11 which cause contamination when attached to the wafer infiltrate. The air cleaning here will be described by operating the harmful gas removing unit A and the fine particle removing unit B. As the storage 1 is opened and closed (the wafer case is taken in and out), the harmful gas 10 and the fine particles 11 in the clean room enter the storage 1, but the heat source inside the storage 1 is the ultraviolet lamp 4 and the heater. Natural circulation flow 13 _{-1 to} 13 _-4 is generated by 12 and the harmful gas 1
0 and the fine particles 11 are collected and removed by the harmful gas removing unit A and the fine particle removing unit B, respectively, and ultra-clean air 13 _-3 is obtained. The air 13 _-3 removes the substance that causes the increase in the contact angle. Therefore, if the air is exposed to the wafer 9 for a long time, the contact angle does not rise, so that the surface of the wafer 9 can be kept stable for a long time. it can.

Next, the fine particle removing section B will be described. The fine particles (particulate matter) 11 in the wafer storage 1 are charged by the photoelectrons 14 emitted from the photoelectron emitting material 5 irradiated by the ultraviolet lamp 4, and become charged fine particles 15. The charged fine particles 13 capture the charged fine particles. The space to be processed (cleaning space, C) in which the wafer is collected and collected by the collecting material 6 is highly cleaned. Since this device is intended to create an ultra-clean space, it is
A new electrode material 7 is installed. That is, the extremely charged fine particles 15 leak without being collected by the collecting material 6 in front.
When flowing out to the rear, the charged fine particles are collected by the rear electrode material 7. This ensures that all the charged fine particles are collected and removed. The photoelectron emission material 5 here is the storage 1
A part of the constituent wall surface of is used. That is, the constituent wall surface is aluminum, and the aluminum is used as a photoelectron supply source.

Since the cleaning device is usually made of aluminum or SUS, the wall surface can be effectively used as a photoelectron emitting material. As described above, it is one of the features of the present invention that a part of the wall surface of the device is used as a photoelectron emitting material. The photoelectron emitting material has another invention of the present inventor as described above and can be appropriately used. The electrode 6 is installed to perform photoelectron emission from the photoelectron emission material 5 in an electric field. That is, an electric field is formed between the photoelectron emitting material 5 and the electrode 6 (photoelectron emitting portion). The charging of the particles is efficiently performed by the photoelectrons 14 generated by irradiating the photoelectron emitting material with ultraviolet rays in an electric field. The voltage of the electric field here is 50 V / cm.

The operation here is, in addition to opening and closing the door of the storage cabinet, releasing (peeling) fine particles from the wafer case and the wall surface of the storage cabinet over time, or the storage cabinet and the wafer carrier in an emergency. Even if the particles are discharged (generated from the vibrating portion) due to vibration or the like, the space C to be processed is continuously operated so as to maintain high cleanliness or intermittently operated at regular intervals. For removal of fine particles by photoelectrons, the method and apparatus already proposed by the present inventors can be appropriately used depending on the application field, apparatus shape, scale, and the like. For example, in addition to the above-mentioned form (configuration), there is a method using a charge collection unit device (Japanese Patent Application No. 3-261289).

Next, the harmful gas removing section A for removing the harmful gas that has entered by opening and closing the storage will be described. By the operation of the above-mentioned fine particle removing section B, the air containing the harmful gas 10 from which the fine particles 11 are removed is passed through the adsorbent of the silica gel 2 and the glass fiber filter 3 of the fluororesin binder by the natural circulation flow 13 _-2. Are collected and removed. It should be noted that the glass fiber filter 3 of the fluororesin binder also has a dust-removing property, and even if dust is generated from the silica gel, it does not flow backward. The operation here may be performed in conjunction with the fine particle removing unit B. C. It is considered that the supply of the pollution source is due to the infiltration of clean room air accompanying the opening and closing of the door of the storage and the organic components of the apparatus and the wafer storage case. Therefore, the intermittent operation in which the operation is performed at regular intervals is preferable.

A feature of the present invention is that a heat source is installed in a closed space (in the storage case in this example) to remove harmful components from harmful gas and fine particles that cause a natural circulation flow and increase the contact angle. It passes through the process and the process of removing fine particles. Therefore, the heating source and the cooling source are installed in a closed space. The temperature difference between heating and cooling serves as the driving force for the circulating flow. The heating source in this example is the ultraviolet lamp 14 and the heater 1.
2 and the cooling coil 16 is used for the cooling unit. In the normal operation, only the ultraviolet lamp 14 may be used as the heating source. However, when the heating is performed immediately after the door is opened or closed or in a clean room where the pollution is severe, it is preferable to use the heater 12 that assists the ultraviolet lamp 14 as the heating source.

Example 2 The following sample gas was placed in a wafer storage having the structure shown in FIG. 1, ultraviolet irradiation and application of a voltage for an electric field were performed, and in the case of an ultraviolet lamp and the temperature difference between the upper and lower portions of the fine particle removing portion B due to heating. The change with time of the particle concentration in the storage and the contact angle on the wafer were measured. Storage size: 80 liters Photoelectron emission material; Use storage wall surface (Al) Electrode material: Cu-Zn plate Charged particulate collection material: Also used as electrode material

Ultraviolet lamp; germicidal lamp, 10 W electric field voltage; 50 V / cm toxic gas trapping material; silica gel (5 liters) and glass fiber filter of fluororesin binder (1 liter) Sample gas (inlet gas): Air (concentration ( Class): 1
Heat source: A tape heater with a built-in nichrome wire heater is installed at the inlet of the charging / collecting section B. Temperature difference in the particulate removal section B (temperature difference between the inlet and the outlet of the section B): 3 ° C. (ultraviolet lamp) Only) 5 ℃, 10 ℃,
20 ° C (use of both UV lamp and heater)

Wafer storage: 15 wafers stored in a wafer case Particle concentration measurement: Light scattering type particle counter Wafer surface particle number measurement: Light scattering type wafer surface particle meter Contact angle measurement Droplet-type contact angle meter The operating time required to obtain the ultimate cleanliness of class 1 in each temperature difference experiment was investigated. In each temperature difference operation, the contact angle on the wafer 60 hours after the operation was examined. As a comparison, the same investigation was performed in the case where the heater heating source was not used. (The above class is 0.1μ present in 1ft ^3.
Total number of fine particles with a particle size of m or more. )

(Results) With respect to the fine particles, the operating time required to obtain class 1 is shown in FIG. 2 and the contact angle is shown in Table 1. When only the ultraviolet lamp was used without using the heater heating source, the temperature difference between the upper part and the lower part of the particle removing portion B was 3 ° C.
The circulation rate between the fine particle removing section B and the space to be cleaned C was measured and found to be 18 liters / m when a heater heating source was not used and the temperature difference was 10 liters / min and 5 ° C.
It was in.

[0040]

[Table 1] If the UV lamp is turned off, 60 hours for 60 hours
Concentrations in the storage after time are class 8,200,7,
The contact angle on the wafer was 500 and the contact angles on the wafer were 10 and 30 degrees, respectively.

Example 3 In Example 2, as a harmful gas trapping material, (1) glass fiber filter of activated carbon and fluororesin binder (2) glass fiber filter of diatomaceous earth and fluororesin binder (3) synthetic zeolite and fluororesin binder Glass fiber filter (4) A glass fiber filter made of silver and a fluororesin binder was used to similarly examine the contact angle. (Results) It was 4 degrees or less at any temperature difference.

Fourth Embodiment FIG. 3 shows a case where the harmful gas removing portion A is installed on the floor surface in the first embodiment. Symbols in FIG. 3 that are the same as those in FIG. 1 have the same meaning.

[0043]

According to the present invention, the following effects can be obtained. (1) In a gas cleaning process including a step of removing harmful components in a gas that increases a contact angle and a step of removing fine particles in the gas by photoelectrons, the step is installed in a closed space, and a closed space is provided. By placing the heating source inside, natural circulation particles are generated in the closed space by the heating source, so that the gas to be treated is effectively circulated in the harmful component removing step and the fine particle removing step. The harmful gas and fine particles that increase the contact angle inside could be removed quickly and easily. That is, a super-clean space capable of preventing an increase in contact angle was quickly and effectively formed. (2) In the above, by using the radiation energy from the ultraviolet lamp in the step of removing fine particles as the heating source, the energy of ultraviolet rays can be effectively used, and the apparatus is made compact. (3) In the above, as a heating source, an auxiliary (for example, a heater or an infrared lamp) heating source can be appropriately added to the ultraviolet lamp, so that required performance, operating conditions, apparatus shape,
Can be cleaned suitable for scale and destination, widening the range of use,
Practicality improved. (4) In the above, since the photoelectron emitting material can utilize the wall surface forming the cleaning device, the device is made compact.

(5) Since the gas to be treated circulates effectively through the harmful gas removing section and the photoelectron-based fine particle removing section, the harmful gas and fine particles in the closed space can be removed quickly and easily. In other words, the ultra-clean space was created quickly and effectively. Conventionally, clean gas was normally obtained with a flow-through (one-pass) device, but in this case the product gas (gas) is released as it is, and there is room for improvement in terms of effective use of the product gas (cleaning gas). there were. Further, in this case, although the treatment is performed in one pass, it is necessary to have a high removal efficiency, and it is necessary to increase the capacity in the configuration of the device, which is a problem in terms of downsizing the device. (6) Since the enclosed space can be handled (treated) as it is,
The cleaning method and device are easy to handle (manipulate), compact and inexpensive. In particular, it was effective for a large-sized device (large-volume clean space). (7) Since harmful gas and fine particles generated in the closed space can be collected quickly and effectively, the practicality is further improved. (8) It can be carried out similarly in various gases such as nitrogen and argon, which is practically effective. (9) 1 to 8 can be widely applied to clean closed spaces in various fields.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of a gas cleaning device used in the present invention.

FIG. 2 shows the relationship between time and temperature difference for obtaining cleanliness class 1.

FIG. 3 is a basic configuration diagram of another gas cleaning device used in the present invention.

[Explanation of symbols]

1: Wafer storage, 2: Silica gel, 3: Glass fiber filter, 4: Ultraviolet lamp, 5: Photoelectron emitting material, 6: Electrode for setting electric field and collector, 7: Collector, 8: Wafer case, 9 : Wafer, 10: Hazardous gas, 11: Fine particles, 1
2: Heater, 13 _{-1 to} 13 _-4 : Circulating flow, 14: Photoelectron, 15: Charged fine particles A: Harmful component removing part, B: Fine particle removing part, C: Cleaning space part

Claims (4)

[Claims] 1. A method of cleaning a gas for preventing an increase in the contact angle of a substrate or a substrate surface, wherein a gas containing harmful components and fine particles in a closed space, and a harmful component in a gas increasing the contact angle are removed. A method for cleaning a gas, characterized in that the step and the step of removing fine particles in the gas by photoelectrons are passed by a gas flow based on a heat source provided in the closed space. 2. A gas cleaning device for preventing an increase in contact angle of a base material or a substrate surface, wherein activated carbon, diatomaceous earth, silica gel, synthetic zeolite, high-purity material for removing harmful components in the gas are enclosed in a closed space. From a harmful gas removing section using at least one adsorbent selected from a molecular compound, a glass material or a fluororesin, and an ultraviolet ray source and / or a radiation source and a radiation source for removing fine particles in the gas A gas comprising: a photoelectron emitting material that emits photoelectrons upon irradiation with a particle, a particle removal unit having an electric field electrode and a charged particle trapping material, and a heat source that generates a gas circulation flow in the closed space. Cleaning equipment. 3. The heat generating source is radiant energy from an ultraviolet ray source of the fine particle removing section.
The gas cleaning device described. 4. The gas cleaning apparatus according to claim 2, wherein a part of a wall surface constituting the cleaning apparatus is a photoelectron emitting material of the particle removing section.