JPH0757981A - Method and equipment for preventing surface contamination of basic material or substrate - Google Patents

Abstract

PURPOSE:To provide a method for preventing surface contamination of a basic material or a substrate by removing fine particles and hydrocarbon effectively. CONSTITUTION:In the method for preventing surface contamination of a basic material or a substrate, a gas 2 containing at least hydrocarbon and coming into contact with a basic material or a substrate is purified by a dust removing means 6 and means for decomposing hydrocarbon by irradiating an optical catalyst 4 with a light 5. When the concentration of particle in the gas dropped to class 10 or below and the concentration of nonmethane hydrocarbon dropped to 0.2ppm or below, the surface of basic material or substrate is exposed to the gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for preventing contamination of a substrate or a substrate surface in a space, and in particular, a raw material, a semi-finished product, a substrate for a cutting edge industry such as semiconductor manufacturing and liquid crystal manufacturing And prevention of contamination on the substrate surface. The application fields of the present invention are, for example, (1) prevention of wafer contamination in a semiconductor manufacturing process, (2) prevention of glass substrate contamination in a liquid crystal manufacturing process, and (3) prevention of substrate contamination in a precision machine manufacturing process.

Examples of places to which the pollution prevention method and apparatus of the present invention are applied include spaces in clean rooms in semiconductor manufacturing factories, liquid crystal manufacturing factories, precision machine manufacturing factories, such as all cabinets, clean boxes, and valuables storage. , Wafer storage, sealed transfer space for valuables, clean sealed space in the presence of various gases or under reduced pressure or under vacuum, transfer space, space containing supply gas to cleaning device, supply air for air knife There is a space.

[0003]

2. Description of the Related Art A conventional technique will be described below by taking air cleaning in a clean room in a semiconductor manufacturing factory as an example.
In a clean room, fine particles (particulate matter),
Gaseous substances such as extremely low concentration hydrocarbons (HC) other than methane in the air caused by exhaust gas of automobiles pose a problem as pollutants. Especially H. C has a very low concentration as a gaseous harmful component in ordinary air (indoor air and outdoor air) and causes pollution, and thus needs to be removed. Also,
Various solvents (alcohols, ketones, etc.) generated during work in a clean room also pose a problem as pollutants.

That is, if the above-mentioned pollutants (fine particles and gaseous pollutants) are deposited on the substrate surfaces of wafers, semi-finished products and products, the substrate surfaces are easily damaged and the productivity (yield) of semiconductor products is reduced. It is necessary to remove the pollutant because it causes the problem. Both the fine particles and the gaseous substance increase the contact angle on the substrate surface. C tends to increase the contact angle. Here, the contact angle is a contact angle of wetting with water, and indicates the degree of contamination on 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 becomes large. Therefore, if the contact angle is large, the degree of contamination is high, and conversely, if the contact angle is small, the degree of contamination is low.

Conventional clean room air purification methods or devices therefor are roughly classified into (1) mechanical filtration methods (HEPA filters, etc.), (2) electrostatic collection of fine particles, and high voltage. There is a filtration method using a charged or conductive filter (HESA filter etc.). All of these methods are aimed at removing fine particles, such as hydrocarbons (HC) other than methane,
It has no effect on the removal of gaseous pollutants which increase the contact angle. On the other hand, H. Known methods for removing C include a combustion decomposition method and an O ₃ decomposition method. However, these methods have a very low concentration of H. It has no effect on the removal of C.

The present inventors have already proposed, as a method and apparatus for preventing the contamination of the substrate or substrate surface, a method and apparatus using an adsorbent, an absorbent or the like for preventing the increase of the contact angle. (Japanese Patent Application No. 3-341802, Japanese Patent Application No. 4-180538). In these methods and devices,
H. Since an adsorbent or an absorbent is used to remove C, there is a problem that waste is generated. Although these methods and devices are effective depending on the application field, further improvement is necessary to further increase their practicality. That is, in order to improve the productivity of semiconductor products, H. It is necessary to effectively remove C.

[0007]

Therefore, an object of the present invention is to increase the contact angle between the fine particles contained in the air introduced into the clean room, the substrate and the surface of the substrate. H.C. that does not effectively remove C or increase contact angle. The purpose is to provide a method and a device that make it possible to convert to C.

[0008]

In order to solve the above problems, the present invention provides a method for preventing contamination of the surface of a base material or a substrate, in which a gas containing at least a hydrocarbon that comes into contact with the base material or the substrate is removed. Means and a means for decomposing hydrocarbons by irradiating light on a photocatalyst, and purifying the fine particles in the gas to have a particle concentration of 10 or less and a non-methane hydrocarbon concentration of 0.2
After adjusting the content to be ppm or less, the gas is exposed to the surface of the base material or the substrate. Further, in the present invention, in an apparatus for preventing contamination of the surface of a base material or a substrate, a dust removing means for removing fine particles to a class 10 or less, which is passed through a gas in contact with the base material or the substrate, and a non-methane hydrocarbon. Of hydrocarbons by photoirradiation on the photocatalyst for removing carbon dioxide to 0.2 ppm or less.

Hereinafter, the present invention will be described in detail by taking the case where the gas contacting the surface of the base material or the substrate is air as an example. The dust removing means in the present invention may be any means as long as it can remove fine particles in the air to a low concentration, and well-known means can be appropriately used. Generally, a well-known dust removal filter that efficiently collects fine particles down to low concentrations,
Alternatively, the present inventor has already proposed to charge and collect fine particles using photoelectrons (eg, Japanese Patent Publication No. 3-5859, Japanese Patent Laid-Open No. 1-59859).
No. 262954, JP-A-4-171061).

In the method using the filter, the HE is generally used.
PA filters, ULPA filters, and electrostatic filters are preferable because they are simple and effective. Usually, one kind or plural kinds of these filters are appropriately combined and used. Next, a method using photoelectrons will be described. In this method, the photoelectron emitting material is irradiated with ultraviolet rays to generate photoelectrons,
The fine particles are charged by the photoelectrons, and the fine particles are removed by collecting the charged fine particles using a collecting material.

The configuration of this system will be described respectively. The photoelectron emitting material may be any material as long as it emits photoelectrons upon irradiation with ultraviolet rays, and a material having a smaller photoelectric work function is more preferable. From the viewpoint of effect and economy, Ba, Sr, C
a, Y, Gd, La, Ce, Nd, Th, Pr, Be,
Zr, Fe, Ni, Zn, Cu, Ag, Pt, Cd, P
b, Al, C, Mg, Au, In, Bi, Nb, Si,
Any one of Ti, Ta, U, B, Bu, Sn, P, W or a compound or alloy or mixture thereof is preferable, and these can be 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, the compounds include oxides, borides, and carbides, and the 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, BuB 6, PrB 6} , ZrB 2 include, as a further carbide UC, ZrC, TaC, TiC, Nb
C, WC, etc.

As the alloy, brass, bronze, phosphor bronze, an alloy of Ag and Mg (Mg is 2 to 20 wt%), Cu
Alloy of Be and Be (1-10 wt% Be) and Ba and Al
The alloy of Ag and Mg can be used, and the alloy of Ag and Mg, the alloy of Cu and Be, and the alloy of Ba and Al are preferable. The oxide can also be obtained by heating only the metal surface in air, or by oxidizing with a chemical.
As another method, it is also possible to heat before use to form an oxide layer 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.

Further, as the present inventor has 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. 2-278123). As an example of this, there is a thin film of Au added as a substance capable of emitting photoelectrons on quartz glass as a UV transparent substance (base material) (Japanese Patent Application No. 2-295423). When the photoelectron emitting material is used by adding it to the base material, the electroconductive material may be added and used as proposed by the present inventor. (Japanese Patent Application No. 3-258718
issue).

The shapes of these materials used are rod-shaped, linear,
Lattice shape, plate shape, pleated shape, curved surface shape, cylindrical shape, wire mesh shape, etc. can be used, and a shape with a large irradiation area of ultraviolet rays is preferable, and depending on the device, fine particles present in the cleaning space part (described later) A device that can be quickly moved to a particle collecting device (described later) is preferable. Depending on the type of particle collector,
An ultraviolet light source, for example, an ultraviolet lamp may be used in which a photoelectron emitting material is arranged (covered) in a thin film on the surface and / or in the vicinity thereof to be integrated. (Japanese Patent Application No. 3-22685
issue). The shape to be used can be appropriately determined depending on the scale of the stocker and the type of the particulate collection device as described later.

The irradiation source for emitting photoelectrons from the photoelectron emitting material may be any one as long as it emits photoelectrons upon irradiation. In addition to the ultraviolet rays described in this example, electromagnetic waves, lasers, and radiations can be appropriately selected and used according to application fields, device scales, shapes, effects, and the like. Among these, in terms of effect and operability,
UV light is usually preferred. Any kind of ultraviolet light may be used as long as the photoelectron emitting material can emit photoelectrons upon irradiation thereof, and one having a sterilizing action is preferable depending on the application field. The types of UV rays are
It can be appropriately determined depending on the 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 ultraviolet ray source can be used, and it can be appropriately selected and used depending on the application field, the shape of the apparatus, 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, it is preferable to use ultraviolet rays having a sterilization (sterilization) wavelength of 254 nm because the sterilization (sterilization) effect can be used together. next,
The position and shape of the photoelectron emitting material and the electric field electrode will be described. The photoelectron emitting material and / or the electrode is installed in a part of the space at an appropriate position in the space where the particles are present so that an electric field can be formed between the electrode and the photoelectron emitting material. An electric field (electric field) is formed between (+). Due to the electric field, photoelectrons are efficiently emitted from the photoelectron emitting material.

The positions and shapes of the photoelectron emitting material and the electrodes can be appropriately selected depending on the scale of the device and the type of the particulate trapping device, and the applied voltage for the electric field can be lowered so that the photoelectrons from the photoelectron emitting material are in space. Any may be used as long as it can effectively charge the fine particles and effectively collect the charged fine particles. Depending on the type of the particulate collector, an ultraviolet source, for example, an ultraviolet lamp having a shape in which a photoelectron emitting material and electrodes are surrounded can be appropriately used. (Japanese Patent Application No. 3-261289
issue). These shapes can be appropriately determined by a preliminary test or the like in consideration of the field of use, the scale of the apparatus, the shape, the effect, the economical efficiency and the like.

Further, a material for collecting charged fine particles (dust collecting material)
Can be used as long as it can collect 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. Electrec material can also be preferably used. 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 also serve as an electric field electrode and a collection of charged particulate matter. It is preferable because it can be done.

The electric field voltage used in the present invention is 0.1 V / cm.
~ 2 kV / cm. The suitable strength of the electric field can be determined by carrying out preliminary tests and studies as appropriate depending on the field of use, conditions, device shape, scale, effect, economical efficiency and the like. By removing fine particles, the concentration of fine particles becomes class 1000 (1000 particles / ft ³ )
The following is preferably class 10 or less. Here, it is a unit of class and particle concentration, and represents the number of particles in 1 ft ³ .

Next, the means for decomposing hydrocarbons by light irradiation on the photocatalyst used in the present invention will be explained. In order to remove non-methane hydrocarbons (gaseous harmful components), H. A photocatalyst that decomposes the C component is used. Non-methane hydrocarbons cause pollution at concentrations in normal air (indoor and outdoor air). In addition, among various non-methane hydrocarbons, 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 diligent studies, the present inventor has found that this is 0.2 pp using non-methane hydrocarbons as an index.
The inventors of the present invention have discovered that it is effective to remove m or less, preferably 0.1 ppm or less, and have reached the present invention.

Next, the photocatalyst will be described. The photocatalyst material may be any as long as it is excited by light irradiation and decomposes non-methane hydrocarbons involved in increasing the contact angle.
Usually, semiconductor materials are preferable because they are effective, easily available, and have good workability. S in terms of effect and economy
e, Ge, Si, Ti, Zn, Cu, Al, Sn, G
a, In, P, As, Sb, C, Cd, S, Te, N
i, Fe, Co, Ag, Mo, Sr, W, Cr, Ba,
Any of Pb, or a compound, an alloy, or an oxide thereof is preferable, and these are used alone or in combination of two or more kinds.

For example, the elements include Si, Ge, Se,
The compounds include AlP, AlAs, GaP, AlSb,
GaAs, InP, GaSb, InAs, InSb, C
dS, CdSe, ZnS, MoS ₂ , WTe ₂ , Cr ₂
Te ₃ , MoTe, Cu ₂ S, WS ₂ , and oxides of TiO ₂ , Bi ₂ O ₃ , CuO, Cu ₂ O, ZnO, M
oO ₃ , InO ₃ , Ag ₂ O, PbO, SrTiO ₃ ,
There are BaTiO ₃ , Co ₃ O ₄ , Fe ₂ O ₃ , NiO and the like.

The installation shape and position of the photocatalyst material may be fixed in the air flow or fixed on the wall surface, and may be used by floating in the air flow. The immobilization of the photocatalyst material is performed by coating the surface of the glass or the gaseous substance with the photocatalyst material, coating the photocatalyst material with an appropriate material such as plate, cotton, net, membrane or fiber, or wrapping, or You may pinch and fix and use it. An example is the coating of titanium dioxide on glass fiber cloth by the sol-gel method. The photocatalyst can be used as it is in powder form,
It may be formed into an appropriate shape by a known method such as sintering, vapor deposition, or sputtering.

These can be appropriately selected depending on the scale and shape and kind of the apparatus, the kind and shape of the light source, the kind of the photocatalyst, the desired effect, the economical efficiency and the like. Further, in order to improve the photocatalytic action, Pt, Ag, Pd, KO is added to the photocatalytic material.
It is also possible to add and use substances such as H, RuO ₂ and Co ₃ O ₄ . The light source for light irradiation may be any one as long as it emits a wavelength absorbed by the photocatalytic material, and light in the visible and / or ultraviolet region is effective, and an ultraviolet lamp or sunlight can be appropriately used. . Generally, an ultraviolet lamp is preferable because of its high processing speed.

When photoelectrons are used as the dust removing means, it is preferable that the type of ultraviolet rays has a wavelength absorbed by the photocatalyst material and a wavelength having energy higher than the photoelectric threshold of the photoelectron emitting material used. It suffices to select a lamp that emits a wavelength in the light absorption region determined by the type of material.
For example, when TiO ₂ is used as the photocatalyst material, a lamp that emits light having a wavelength outside the near-ultraviolet region is used because the light absorption is in the near-ultraviolet region. As the light source, a mercury lamp, a hydrogen discharge tube, a xenon discharge tube, a Lyman discharge tube, or the like is appropriately used in one kind or in two or more kinds.

[0027]

The substances which cause contamination of the substrate or substrate surface and increase the contact angle are (1) SOx, NOx, HCl,
Harmful gas such as NH ₃ , (2) fine particles, (3) H.
As a result of a study by the present inventor, the contact was observed in normal air (environmental air in a normal clean room) or N ₂ used in a clean room such as a semiconductor manufacturing factory or a liquid crystal manufacturing factory. The fine particles and H. C
Is greatly affected. That is, generally SOx, NOx, H
Cl and NH ₃ have little effect on the increase of the contact angle at normal concentration levels in air. Therefore, dust removal and H. The effect is obtained by removing C. In particular, H. C is effective when the non-methane hydrocarbon is used as an index and is removed to 0.2 ppm or less, preferably 0.1 ppm or less.

H. The C component is said to be a mixture of hundreds or thousands of components. It is unknown which component of the C component contributes to the increase of the contact angle and to what extent. Therefore, the details of the mechanism for preventing the increase of the contact angle due to the photocatalyst are unknown, but it is considered as follows. The increase in contact angle is described by H.
It is presumed that substances having particularly large molecular weight and substances having high activity among C components are greatly affected, and it is considered that these are effectively decomposed by the action of the photocatalyst.

In other words, the photocatalyst effectively converts the substance having a large molecular weight and the substance having a high activity into H. Depending on the C type, H. Decomposed into C, carbon dioxide and water.
H. 3 having a low molecular weight. Since C, carbon dioxide, and water do not participate in the increase in contact angle, exposing such air to the surface of the base material or substrate brings about the effect of preventing increase in the contact angle of the base material or substrate surface.

On the other hand, when harmful gases such as SOx are generated in or around the clean room and their concentrations are high, they are affected by these gas components, and when these concentrations are so low that they do not usually affect. However, it may be affected when the substrate or the substrate is sensitive or when the surface is in a special state (for example, when the substrate surface is coated with a special thin film). In such a case, a method (apparatus) (Japanese Patent Application No. 3-22686) proposed by the present inventor to irradiate harmful gas with ultraviolet rays and / or radiation to atomize the gas and collect the particles is proposed. It is preferable to use a suitable combination. In such a case, another known harmful gas removing material such as activated carbon or ion exchange resin may be appropriately combined and used. Activated carbon may be one that is impregnated with an acid or an alkali, or is appropriately modified by a known method.

Furthermore, H.264. For the purpose of removing C, H.C. A method of collecting C by making it into fine particles (Japanese Patent Application No. 3-105092), a method of collecting using an adsorbent or an absorbent (Japanese Patent Application No. 3-341802, Japanese Patent Application No. 4-18).
No. 0538, PCT / JP92 / 01579), fields of use, equipment type, scale, H. It can be used in an appropriate combination depending on the concentration of C, coexisting components, required performance and the like.

[0032]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. Example 1 FIG. 1 is an example in which the method of the present invention is applied to purification of supply air for an air knife in a semiconductor manufacturing factory. In FIG. 1, reference numeral 1 denotes a clean room of class 10000, in which air 2 is a coarse filter 3 and an H.V.
Contamination prevention device 7 including photocatalyst 4 for decomposing C, ultraviolet lamp 5 for irradiating the photocatalyst with ultraviolet rays, and dust filter 6
Are processed in the clean room 1. After passing through the device 7, the air 2 is dedusted and H. Clean air 8 in which the C component is decomposed into a wafer (substrate)
Is supplied to the air knife device 9 for cleaning the.

The present example will be described in detail below. The outside air 10 before entering the clean room 1 is first treated by the coarse filter 11 and the air conditioner 12. Then, when the air enters the clean room 1, it is dust-removed by the HEPA filter 13 and has an extremely low concentration of H.V. The air 14 has a concentration of class 10000 in which C coexists. That is, the H.V. C is a coarse filter 11 and an air conditioner 1
2 and since it is not removed by the HEPA filter 13,
It is introduced into the clean room 1. H. in air 14 and 2 The concentration of C is non-methane. 0.5 to 0.8 at C
ppm.

The air 2 is first dust-removed by the coarse filter 3. This filter is installed to prevent the photocatalyst from being physically contaminated by the dust (particulate matter) when the dust is generated in the clean room 1 and the performance is deteriorated. Then, the H. The air containing C.H.C. is composed of a photocatalyst (titanium dioxide coated on glass fiber) 4 and an ultraviolet lamp (high pressure lamp) 5. It is introduced into the C decomposition section, where H. C is non-methane H. It is decomposed to 0.2 ppm or less, preferably 0.1 ppm or less with C as an index.

As a result, H. C and active H. C is H. The H. C. having a small molecular weight does not increase the contact angle depending on the type of C. C or decomposed into carbon dioxide or water. The dust-removing filter 6 is used for cleaning fine particles having a concentration of class 10000 in a clean room and H.264 in an emergency. It efficiently collects fine particles flowing out from the C decomposition section or its periphery (dust removing section), and uses a ULPA filter. The ULPA filter removes fine particles up to class 10. Photocatalytic H. The positions of the C disassembling section and the dust removing section by the filter are H.S. C
The decomposition part is in the front and the dust removal part is in the rear, but it is not limited at all, and the concentration of fine particles in the gas exposed to the substrate or substrate surface is class 10 or less, and the concentration of non-methane hydrocarbon is 0.2 ppm.
Any position and configuration may be used as long as they are as follows.

Example 2 Air cleaning of a wafer storage (wafer storage stocker) in a semiconductor factory in a class 10000 clean room was performed.
This will be described with reference to the basic configuration diagram of the present invention shown in FIG. As the air cleaning of the wafer storage 21, the removal of fine particles will be described first. The particles are removed by an ultraviolet lamp 22 installed on one side of the wafer storage 21, an ultraviolet reflecting surface 23, a photoelectron emitting material 24, an electrode 25 for setting an electric field, and a charged particle collecting material 25 (particle collecting device). Will be implemented in. In this structure, the electrode is also used as a collector.

That is, the fine particles (fine particle substances) 26 in the wafer storage 21 are UV lamps (sterilization lamps).
Are charged by the photoelectrons 27 emitted from the photoelectron emitting material 24 irradiated with the ultraviolet rays from the particles, and become charged fine particles 28, and the charged fine particles 28 are collected by the charged particle collecting material 25 (fine particle collecting device B), The to-be-processed space part (cleaning space part, A) where the wafer exists is highly cleaned. 32a,
32b and 32c show the flow of air in the storage. That is, the air that has moved to the charging / collecting unit (B) for the particles is heated by the irradiation of the ultraviolet lamp, so that an ascending air current is generated and moves in the storage 21 as indicated by arrows 32a, 32b, and 32c. Due to the movement of this air, the particles 26 in the storage are
Effectively moves to the particle charging / collecting device B, so that the inside of the storage 21 is quickly cleaned.

Here, the light shielding material 29 is installed between the space A to be processed and the fine particle collecting portion B, and the ultraviolet lamp 22.
It prevents the ultraviolet light from the wafer from directly irradiating the wafer 31 in the wafer carrier 30. Photoelectron emission material 2 here
No. 4 has a thin film of Au added to the surface of the glass material, and there is another invention of the present inventor regarding the photoelectron emitting material having such a structure (Japanese Patent Application No. 2-295423). In this way, the fine particles (particulate matter) 26 in the wafer storage 21 are collected and removed.

In the above, for the irradiation of the photoelectron emitting material with ultraviolet rays, the curved reflecting surface 23 is used, and the ultraviolet lamp 22 is used.
In this way, the plate-like photoelectron emitting material 24 is efficiently irradiated with ultraviolet rays. The electrode 25 is installed to perform photoelectron emission from the photoelectron emission material 24 in an electric field. That is, an electric field is formed between the photoelectron emitting material 24 and the electrode 25 (photoelectron emitting portion). The particles are charged by photoelectrons 27 generated by irradiating the photoelectron emitting material 24 with ultraviolet rays in an electric field.
Will be implemented more efficiently. The electric field voltage here is 5
It is 0 V / cm. Further, the charged particles are collected by using the electrode 25. The electrode material is a wire-mesh Cu-Zn material plated with gold and used at a position 1 cm from the photoelectron emission material (total length A
It is installed at a position of 0.03 with respect to the distance 1 of + B).

Next, H. C removal will be described. H.
C removal is carried out by a photocatalyst (titanium dioxide coated on glass fiber) 33 irradiated with an ultraviolet lamp (sterilization lamp) 22. The air in the clean room of class 10000 in which the storage 21 is installed is entered into the wafer storage 21 by opening and closing the storage 21. This air contains H. C is 0.8 to 1.
Contains 5 ppm. The H. Air containing C is the flow of air 3
3a, 33b, 33c contact the photocatalyst 33, and H. C and active H. C is effective in H. Depending on the type of C. Decomposed into C, carbon dioxide or water. H. C is decomposed to 0.1 ppm or less using non-methane hydrocarbon as an index.

As described above, fine particle removal (dust removal) and H. Due to the decomposition of C, the cleaning space A is cleaned and the inside of the storage chamber becomes ultra-clean air. Thus, by exposing the wafer surface to the ultra-clean air, the wafer surface is prevented from being contaminated. As a result, the contact angle on the wafer is prevented from increasing. A combination of the method (apparatus) already proposed by the inventor and the method of the present invention, or H.264. The use and combination of materials that remove harmful gases other than C can be appropriately selected and used. The conditions for using the dust filter and the photocatalyst can be appropriately determined. That is,
These may be appropriately preliminarily tested depending on the concentration and type of pollutants (fine particles, HC, and other harmful gases) in the clean room to be used, type of applicable equipment, structure, scale, required performance, efficiency, economic efficiency, etc. You can decide by going.

In this embodiment, the case where the medium is air has been described, but it is needless to say that the present invention can be similarly applied to the case where fine particles or gaseous toxic substances are contained as impurities in other gases such as nitrogen and argon. . The space to which the present invention can be applied refers to under pressure, under reduced pressure, or under vacuum, in addition to the above-mentioned atmospheric pressure, and can be similarly implemented.

Example 3 With the apparatus shown in FIG. 1, fine particles were removed from the air in the clean room and H. C was decomposed. The glass substrate was exposed to the purified air thus obtained, and the contact angle was measured. At the outlet of the pollution control device, the particle concentration and non-methane H. The concentration of C was measured. In addition, the same measurement was performed on the apparatus shown in FIG. 1 from which the ultraviolet lamp and the photocatalyst were removed (that is, only the dust filter was used) and the dust filter was removed (that is, only the photocatalyst was used), and before treatment in the clean room. The same measurement was performed when the glass substrate was exposed to the air.

Test conditions Fine particle concentration in clean room before treatment: Class 1
0000 Non-methane H. Concentration of C:
0.8-1.0 ppm Dust removal filter: ULPA (Nippon Pall Co., Ltd., Gas Clean Filter SGLF6101) Photocatalyst: Titanium dioxide coated on glass fiber, manufactured by sol-gel method. Light source: High pressure lamp Contact angle measuring device: CA-D type contact angle meter manufactured by Kyowa Interface Science Co., Ltd. Pretreatment of glass substrate: O after cleaning with detergent and alcohol
₃ UV irradiation under generation

[0045] The relationship between the contact angle exposure is time and the measurement of the glass substrate θ to result air is shown in FIG. In FIG. 3, the present invention A
(Uses a coarse filter, photocatalyst, dust filter) is-○-
Indicate. For comparison, from the present invention (A), the one without the ultraviolet lamp and the photocatalyst (B) is-□-, the one without the dust filter (C) is -Δ-, and before treatment in the clean room. Those exposed to air (D)-●-
Indicate. The frequency at which the contact angle meter used can detect the contact angle (the lower limit of detection of the contact angle) is 3 to 4 degrees, and in the case of the present invention in which the coarse filter, the photocatalyst, and the dust removal filter are used at the same time, the detection limit (↓ )showed that. The particle concentration at the outlet of the device is class 10 or less (measuring device: light scattering type particle counter), and non-methane H. The concentration of C was 0.1 ppm or less (measuring instrument: gas chromatograph).

Example 4 The following sample gas was put into a storage having the configuration shown in FIG. 2, an electric field voltage was applied and ultraviolet rays were applied, and a fine particle concentration meter (particle counter) was used to measure the concentration of fine particles in the storage and The contact angle on the wafer stored in the storage was examined using a contact angle measuring device. In addition, the concentration of non-methane hydrocarbons in the storage was measured. For comparison, the same operation was performed when the ultraviolet lamp was not turned on and the voltage for the electric field was not applied.

Test conditions Storage size: 30 liters Photoelectron emitting material; Quartz glass with Au added in thin film form Electrode material: Wire mesh Cu-Zn 1 cm from photoelectron emitting material (opposite photoelectron emitting material) Installed at a distance of 0.03 to the wall surface (position of 0.03 against the total length) Charged particulate collection material; Electrode material also used UV lamp; Sterilization lamp Electric field voltage; 50 V / cm Sample gas (inlet gas); Medium gas ... Air concentration (Class): 10,000 (class; number of particles of 0.1 μm or more in 1 ft ³ )

Irradiation time: 30 minutes, 1 hour, 16 hours Fine particle concentration in clean room before treatment: Class 1
0000 Non-methane H. Concentration of C:
0.8-1.0 ppm Dust removal filter: ULPA (Nippon Pall Co., Ltd., Gas Clean Filter SGLF6101) Photocatalyst: Titanium dioxide coated on glass fiber, manufactured by sol-gel method. Light source: High-pressure lamp Contact angle measuring device: CA-D type contact angle meter manufactured by Kyowa Interface Science Co., Ltd. Wafer; 5 inch wafer is cut into 1 cm x 8 cm and installed in the storage. Wafer pretreatment: After cleaning with detergent and alcohol, UV irradiation under O ₃ generation

[0049] it was measured particle concentrations above results 0.1μm in the instrument. The results are shown in Table 1 by the number (class) of fine particles in ft ³ .

[Table 1]

Table 2 shows the contact angle on the wafer.

[Table 2]

For comparison, Table 3 shows the particle concentration in the storage and the contact angle on the wafer when the photocatalyst was not turned on and no voltage was applied.

[Table 3] The frequency at which the contact angle of the contact angle meter used can be detected (the lower limit of detection of the contact angle) is 3 to 4 degrees. In addition, non-methane H. The concentration of C was 0.1 ppm or less (measuring instrument: gas chromatograph).

[0052]

According to the present invention, the following effects can be obtained. (1) H. By providing the C decomposing means, the photocatalyst enables the H.V. C. has a small molecular weight. C and / or carbon dioxide, converted to water. By adding dust removal to the above (1), a gas or atmosphere (environment) in which an increase in contact angle was prevented was obtained. If the gas (or atmosphere) obtained in (2) above is exposed to a substrate or substrate (raw material, semi-finished product, or product) such as a semiconductor wafer or liquid crystal glass, contamination of the substrate or substrate surface can be prevented. To be done. The photocatalytic material is H.264. Compared with the adsorbent and absorbent of C, the stable performance is maintained for a long time, so that the practicality is improved.

(2) When the photoelectrons already proposed by the present inventor are used as the dust removing means, the light source can be used in common, and the dust removing device using the photoelectrons can be easily integrated. Practicality improved. (3) NOx and SOx other than hydrocarbons in the gas to be treated
When the concentration of gaseous harmful components such as is high, a method for removing these harmful components (for example, the method already proposed by the present inventor)
Was appropriately selected and combined with the method for removing hydrocarbons according to the present invention, the field of application of the present invention was expanded, and pollution was prevented more effectively.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a clean room in which a pollution prevention device of the present invention is installed.

FIG. 2 is a schematic configuration diagram of a wafer storage in which the pollution prevention device of the present invention is installed.

FIG. 3 is a graph showing the relationship between exposure time and contact angle.

[Explanation of symbols]

1: Clean room, 2, 14: Air, 3: Coarse filter, 4, 33: Photocatalyst, 5, 22: Ultraviolet lamp, 6:
Dust filter, 7: Pollution control device, 8: Clean air, 9:
Air knife device, 10: outside air, 11: coarse filter, 1
2: Air conditioner, 13: HEPA filter, 21: Wafer storage, 23: Reflective surface, 24: Photoelectron emitting material, 25:
Electrodes, 26: Fine particles, 27: Photoelectrons, 28: Charged fine particles, 29: Light shielding plate, 30: Wafer carrier, 31: Wafer, 32: Air flow

Claims (2)

[Claims] 1. A method for preventing contamination of the surface of a base material or a substrate, wherein a gas containing at least a hydrocarbon that comes into contact with the base material or the substrate is removed by a dust removing means and a hydrocarbon decomposing means by light irradiation onto a photocatalyst. Purified, the fine particle concentration in the gas is class 10 or less, the non-methane hydrocarbon concentration is 0.2
A method for preventing contamination of a surface of a substrate or a substrate, which comprises exposing the gas to the surface of the substrate or the substrate after the concentration is adjusted to be ppm or less. 2. A device for preventing contamination of the surface of a base material or a substrate, a dust removing means for removing fine particles to a class 10 or less by passing a gas in contact with the base material or the substrate, and a non-methane hydrocarbon concentration. And a means for decomposing hydrocarbons by irradiating the photocatalyst with light to remove 0.2 to 0.2 ppm or less of the base material or substrate surface contamination prevention device.