JP3141341B2 - Method and apparatus for preventing increase in contact angle of substrate or substrate surface in closed space - Google Patents

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 particularly to a raw material, a semi-finished product, and a substrate of a product in advanced industries such as semiconductor production and liquid crystal production. And prevention of contamination of the substrate surface. The application fields of the present invention are, for example, (1) prevention of contamination of a wafer in a semiconductor manufacturing process, (2) prevention of contamination of a glass substrate in a liquid crystal manufacturing process, and (3) prevention of contamination of a base material in a precision machine manufacturing process. Examples of locations to which the contamination prevention method and apparatus of the present invention are applied include a semiconductor manufacturing plant, a liquid crystal manufacturing plant,
There is a space in a clean room in a precision machine manufacturing factory or the like, for example, all cabinets, a clean box, a storage for valuables, a wafer storage, a liquid crystal storage, and a sealed transfer space for valuables.

[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.
In a clean room, fine particles (particulate matter)
Gaseous substances such as hydrocarbons (HC) at extremely low concentrations other than methane in the air due to automobile exhaust gas and the like pose a problem as pollutants. In particular, HC must be removed as a gaseous harmful component having a very low concentration in ordinary air (room air and outside air) causes contamination. Further, various solvents (alcohols, ketones, etc.) generated in the operation in the clean room also pose a problem as a pollutant.

[0003] That is, if the above-mentioned contaminants (fine particles and gaseous harmful components) are deposited on the substrate surface of a wafer, semi-finished product, or product, the substrate surface is likely to be damaged, and the productivity (yield) of semiconductor products is reduced. It is necessary to remove contaminants because they cause this. Although both the fine particles and the gaseous substance increase the contact angle on the substrate surface, particularly in a normal clean room, HC tends to increase the contact angle. Here, the contact angle is a contact angle of wetting by water, and indicates a degree of contamination of the substrate surface. That is, when a hydrophobic (oil-based) substance adheres to the substrate surface, the surface repels water and becomes hard 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.

[0004] Conventional clean room air purification methods or apparatuses therefor are roughly classified into (1) a mechanical filtration method (such as a HEPA filter), and (2) a high-voltage method for electrostatically collecting fine particles. There is a filtration method using a charged or conductive filter (such as a HESA filter). All of these methods aim at removing fine particles and have no effect on removing gaseous pollutants that increase the contact angle, such as hydrocarbons other than methane (non-methane HC). On the other hand, HC which is a gaseous pollutant
As a method for removing methane, a combustion decomposition method, an O ₃ decomposition method, and the like are known. However, these methods are not effective in removing extremely low concentrations of HC contained in the air introduced into the clean room.

[0005] As the gaseous harmful components other than HC, SOx, NOx, HCl, include NH _3, as these removal methods, neutralization reaction and the oxidation reaction using an appropriate alkaline substance or acidic substance There is a known method for utilizing the method. However, these methods have little effect when the concentration of the components is extremely low such as contained in the air introduced into the clean room. The present inventors have already proposed, as a method and an apparatus for preventing contamination of a substrate or a substrate surface, a method and an apparatus using an adsorbent, an absorbent or the like for preventing the increase in the contact angle (see Japanese Patent Application No. 2006-122857). Hei 3-341
No. 802, Japanese Patent Application No. 4-180538, Japanese Patent Application No. 5-14
No. 5073). Although these methods and apparatuses are effective in some application fields, depending on the application fields and types of apparatuses, further improvements need to be made to further increase the practicality.

That is, in order to improve the productivity of semiconductor products, it is necessary to more preferably remove particulate matter and gaseous harmful components which increase the contact angle depending on the application field and the type of equipment. The known technique that the present inventors have already proposed will be described with reference to the drawings. FIG. 2 shows an example in which the method proposed by the present inventors is applied to purification of supply air for an air knife in a semiconductor manufacturing plant. In FIG. 2, reference numeral 1 denotes a class 10000 clean room, in which air 2 includes a dehumidifier 3, an adsorbent 4 that adsorbs gaseous harmful components (mainly HC in this example) that increase the contact angle,
And a pollution prevention device 6 comprising a dust filter 5
It is processed in the clean room 1. After passing through the apparatus 6, the air 7 becomes clean air from which dust and gaseous harmful components have been removed, and is supplied to an air knife apparatus 8 for cleaning a wafer (substrate).

Hereinafter, FIG. 2 will be described in detail. The outside air 9 before entering the clean room 1 is first processed by the coarse filter 10 and the air conditioner 11. Next, the air is removed by the HEPA filter 12 when entering the clean room 1, and becomes air 13 having a class 10000 concentration in which extremely low concentration HC coexists. That is, the extremely low-concentration HC mainly generated from the vehicle is not removed by the coarse filter 10, the air conditioner 11, and the HEPA filter 12, and is introduced into the clean room 1. The concentration of HC in the air 13 is 0.5 to 0.8 ppm of non-methane HC. Moisture (RH 40-60%), fine particles (class 1000
0), and the air 2 in the clean room 1 containing the extremely low concentration of HC is first dehumidified by a dehumidifier (dehumidifier) 3 so that the water concentration is equal to or less than a certain concentration. The dehumidifier of this example is of an electronic dehumidification type, and is operated so that the humidity (RH 40 to 60%) in the clean room 1 is 30% or less. The air after the dehumidification is then treated by an HC adsorbent, that is, a gas adsorption and removal device 4, whereby an extremely low concentration of HC is removed.

As shown in FIG. 2, in the method of purifying the air 2 to be treated in the clean room 1 by passing it through the pollution control device 6 in one pass, it is necessary to obtain high-quality air 7 in one pass. Since the use conditions must be optimized, the adsorbent cannot be used up to the adsorption capacity, the life of the adsorbent is short, and the clean air 7 obtained as described above can be removed from the apparatus 8 in one pass. Therefore, there is room for improvement in terms of effective use of the high-quality air 7. Further, in such a one-pass processing method, since a large amount of air to be processed needs to be rapidly processed, the adsorbent 4 is greatly affected by moisture depending on the use conditions of the adsorbent. In treating the air to be treated 2 with the adsorbent 4, it is necessary to keep the moisture concentration at 30% (RH) or less by the dehumidifier 3 in advance. Therefore, as a practical problem, there is a problem that an apparatus configuration for easily removing the drain from the dehumidifier is desirable.

[0009]

As described above, in order to improve the productivity of products in advanced industries such as semiconductors and liquid crystals, particulate matter and harmful components that increase the contact angle are effectively and sufficiently reduced. Need to be removed. Accordingly, an object of the present invention is to provide a method and an apparatus for preventing an increase in contact angle in a closed space that effectively removes particulate matter and gaseous harmful components that increase the contact angle between the substrate and the substrate surface. .

[0010]

In order to solve the above-mentioned problems, the present invention provides a method for preventing an increase in the contact angle of the surface of a substrate or a substrate in an enclosed space. Particle concentration in the class is 10
Hereinafter, cleaning is performed by dust removal and adsorption treatment so that the concentration of non-methane hydrocarbons becomes 0.2 ppm or less, and the purified gas is ventilated into a closed space containing a base material or a substrate. Gas in the enclosed space when circulating
Is intermittently cleaned by a circulation device and circulated,
Is obtained by the contact angle increase prevention method of a substrate or substrate surface in the sealed space, wherein the this <br/> to prevent backflow into the cleaning process closed space in front of the gas. Further, according to the present invention, in a device for preventing an increase in the contact angle of the surface of a substrate or a substrate in an enclosed space, the enclosed space for accommodating the substrate or the substrate and the concentration of fine particles in a gas are reduced to class 10 or less. A gas purifying device having a dust removing means for removing the non-methane hydrocarbon concentration to 0.2 ppm or less, and a gas purifying device, and circulating the gas in the closed space between the closed space and the gas purifying device. Gas circulating means for circulating gas.
Intermittent in the flow path from the enclosed space to the gas purifier
An apparatus for preventing an increase in the contact angle of a surface of a substrate or a substrate in a closed space, comprising a circulating device to be operated and a backflow preventing means .

Next, the present invention will be described in detail. The present invention mainly comprises the following three components: a space to be cleaned, which is a closed space for accommodating a base material or a substrate; a gas purifying unit for purifying gas in the space to be cleaned; It is composed of a gas circulation operating section for circulating the space and the gas cleaning section. In the present invention, an ultra-clean space is easily created with the three configurations, and the ultra-clean space can be maintained for a long time. First, the gas cleaning unit will be described. The gas purifying section of the present invention includes a portion (dust removing means) for removing fine particles (particulate matter) in a gas containing HC, and a portion (HC adsorbing means) for removing HC.

Each configuration will be described in detail. The dust removing means may be of any type as long as it can remove fine particles in the air to a low concentration. Usually, a well-known dust filter that efficiently collects fine particles to a low concentration is used.
Generally, HEPA filters, ULPA filters, metal filters, and electrostatic filters are preferred because they are simple and effective. Usually, one or more of these filters are used in appropriate combination. By removing the fine particles, the fine particle concentration can be reduced to class 10 (10 particles / ft ³ ) or less.
It is preferably class 1 or less. Here, the class is a unit of fine particle concentration, and represents the number of fine particles in 1 ft ³ . The HC adsorbing means uses a material that adsorbs and removes gaseous harmful components that are non-methane HC in order to adsorb and remove HC components that increase the contact angle. Non-methane HCs cause pollution at concentrations in normal air (room air and outside air). Further, among various non-methane HCs, 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 determined that non-methane HC is an index,
It has been found that it is effective to remove this to 0.2 ppm or less, preferably 0.1 ppm or less.

As the adsorbent, activated carbon, silica gel, synthetic zeolite, molecular sieve, high molecular compound (for example, styrene-based polymer, styrene-divinylbenzene copolymer), glass, fluorine compound, metal / ion exchanger and the like are used. . As the glass material, an oxide glass system, for example, silicate glass or phosphate glass is generally used.
As silicate glass, borosilicate glass (main component: Na ₂ O—B ₂ O ₃ —SiO ₂ ) is particularly preferred because it is easy to mold, has a high adsorption effect, and is inexpensive. When the glass surface is coated with a metal thin film of Ti, Au, Al, Cr or the like, the adsorption effect is enhanced. As the fluorine compound, tetrafluoride resin, 4-hexafluoride resin, PF
A resin, ethylene trifluoride resin, ethylene tetrafluoride-ethylene copolymer, vinylidene fluoride resin, vinyl fluoride resin, graphite fluoride, Teflon and the like.

The shapes of glass and fluorine compound used include filter, fiber, net, sphere, pellet, lattice,
There are a rod shape and a pleated shape. 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 a filter, there is a method in which a fluorine compound resin is used as a binder and a fibrous glass material is solidified into a filter. When used in such a filter form, the dust removal performance is added to the HC removal performance, so that the filter configuration is simplified. Therefore, incorporating such an adsorbent into a pollution control device is preferable depending on the field of use, the scale of the device, and the shape of the device. Examples of the metal include Fe, Ag, Ni, Cr, T
i, Au, Pt, powdery, plate-like, sponge-like, cotton-like, fibrous, or those added to an appropriate carrier, such as silica-alumina gel carrying Ag or zirconium phosphate with Ag A supported shape can be suitably used.

[0015] The ion exchanger has an adsorbed H on a substrate or a substrate.
Any material that can capture C may be used. As described later, the HC to be removed varies depending on the type of the base material or the substrate surface, etc., and thus can be selected and used through preliminary tests and studies. As the ion exchanger, those having various shapes such as a granular shape, a bead shape, a fibrous shape, and a filter shape manufactured by known means can be used. Usually, a fibrous (filter-like) ion-exchange fiber is preferable because of its low pressure loss and high collection speed. As the ion-exchange fiber, those previously proposed by the present inventors can be appropriately used (Japanese Patent Publication No. 5-67325).
No., Japanese Patent Publication No. 6-87997, Japanese Patent Application No. 6-284
004). Describing the ion exchange fiber, it is a natural fiber or a synthetic fiber, or a cation exchanger or an anion exchanger on a support surface such as a mixture thereof,
Or, an ion exchanger having both a cation exchange group and an anion exchange group is supported, and as a method, it may be directly supported on a fibrous support, and may be woven, knitted or flocking. After being formed, it can be supported by this. In any case, it suffices if the fibers finally support the ion exchanger.

As the method for producing the ion-exchange fiber used in the present invention, an ion-exchange fiber produced by using a graft polymerization method, especially a radiation graft polymerization method, is preferable. This is because various materials and shapes can be used. Well, wool, silk and the like can be applied as the natural fibers, and synthetic fibers made of a hydrocarbon-based polymer, those made of a fluorinated polymer, or polyvinyl alcohol, polyamide, polyester, polyacrylonitrile , Cellulose, cellulose acetate and the like can be applied.
As the hydrocarbon polymer, polyethylene, polypropylene, polybutylene, aliphatic polymers such as polybutene, polystyrene, aromatic polymers such as poly α-methylstyrene, alicyclic polymers such as polyvinylcyclohexane or These copolymers are used. Examples of the fluorinated polymer include polytetrafluoroethylene, polyvinylidene fluoride, ethylene-tetrafluoroethylene copolymer, ethylene tetrafluoride-hexafluoropropylene copolymer, and vinylidene fluoride-hexafluoride. A propylene copolymer is used.

In any case, the support has a large contact area with the gas flow, a small resistance, a shape that can be easily grafted, a high mechanical strength, a loss of fiber waste, generation of heat and heat. The influence of acid, alkali, or a material having a small influence of a solvent may be selected as appropriate, and it can be appropriately selected in consideration of the intended use, economy, effects, etc. Usually, polyethylene is generally used, and polyethylene or polyethylene and polypropylene are usually used. Are particularly preferred. Next, as the ion exchanger, various cation exchangers or ion exchangers can be used without particular limitation. For example, in the case of cation exchange, for example, carboxyl groups, sulfonic acid groups, phosphoric acid groups, cation exchange group-containing substances such as phenolic hydroxyl groups, primary to tertiary amino groups, quaternary ammonium groups and the like And an ion exchanger having both the positive and negative ion exchange groups.

Specifically, styrene compounds such as acrylic acid, methacrylic acid, vinylbenzenesulfonic acid, styrene, halomethylstyrene, acyloxystyrene, hydroxystyrene, aminostyrene, etc.
Vinylpyridine, 2-methyl-5-vinylpyridine, 2
After graft polymerization of -methyl-5-vinylimidazole and acrylonitrile, if necessary, sulfuric acid, chlorosulfonic acid, sulfonic acid and the like are reacted to obtain a fibrous ion exchanger having a cation or anion exchange group. These monomers can also be graft-polymerized onto fibers in the presence of a monomer having two or more double bonds, such as divinylbenzene, trivinylbenzene, butadiene, ethylene glycol, divinyl ether, ethylene glycol dimethacrylate, and the like. Good.

Thus, an ion exchange fiber is manufactured. The diameter of the ion-exchange fiber is from 1 to 1000 μm, preferably from 5 to 200 μm, and can be appropriately determined depending on the type and use of the fiber. Of these ion exchange fibers,
How to use the cation exchange group and the anion exchange group can be determined depending on the type and concentration of the component to be removed in the target processing gas. For example, the components to be removed may be measured and evaluated in advance, and the type and amount of ion exchange fibers corresponding to the measured and evaluated values may be used. Ion exchange fibers can also collect ionic substances that coexist,
It is preferable depending on the field of use (Japanese Patent Application No. 6-145073).
issue). Among the above adsorbents, silica gel, synthetic zeolite, polymer compound, glass, fluorine compound, metal and ion exchange fiber are more preferable because of their high adsorption effect. These adsorbents can be used alone or in an appropriate combination of two or more types (JP-A-5-157284, JP-A-6-32).
No. 4, each gazette, Japanese Patent Application No. 5-145073).

Here, the collection by the ion exchanger is not necessarily limited to the adsorption action, but may involve a chemical reaction. However, since the concentration of HC to be removed is extremely low, the collection and removal mechanism is not provided. Details are unknown, and here, adsorption was used. As will be described later, there are a plurality of types of HC involved in increasing the contact angle, and thus it is effective to use a combination of two or more types of adsorbents. That is, since there is a limit in collecting all the HCs involved in increasing the contact angle depending on the trapping by one kind of adsorbent, it is necessary to conduct experiments and use an appropriate combination of adsorbents having different adsorption characteristics. It is effective.
In addition, the degree of the effect of HC differs depending on the type of silicon wafer substrate or glass substrate, or depending on the surface state of the substrate. However, the application field, the scale of the apparatus, the shape, the use conditions of the apparatus, coexisting gas, required performance, and economic efficiency Preliminary tests are appropriately performed according to the method described above, and a suitable one can be selected from the above adsorbents.

The HC component in the air is said to be a mixture of hundreds or thousands or more components, and which of these various HC components contributes to the increase in the contact angle and to what extent. Is considered to depend on the state of the base material and the surface of the substrate, and has not been sufficiently clarified. For this reason, the details of the mechanism for preventing the contact angle from increasing due to the adsorbent are largely unknown, but may be considered as follows. In other words, it is presumed that a substance having a particularly high molecular weight or a substance having a high activity among the HC components has a large effect on the increase in the contact angle. Can not be collected at the same time (collection is limited). On the other hand, by using a plurality of adsorbents having different characteristics, effective collection becomes possible. For example, depending on the type of the base material or the substrate, HC that increases the contact angle
Has hydrophilicity and hydrophobicity, so in such a case,
The use of a hydrophilic and hydrophobic adsorbent is effective.

For example, in the case of a glass substrate, HC that is adsorbed on the glass substrate and causes an increase in the contact angle is C ₁₆ -C
High molecular weight H having -CO-, -COO- bonds of ₂₀
C _(eg, higher fatty acid in the range of C 16 _{-C 20,} phthalic acid esters, phenol derivatives) is. Such HC
Adsorbents that trap and remove water are hydrophilic adsorbents (eg, silica gel, synthetic zeolite, molecular sieve, alumina, etc.) and hydrophobic adsorbents (eg, fibrous borosilicate glass with tetrafluoride resin as binder) A combination of a glass and a fluorine compound, such as a solidified filter, is effective (Japanese Patent Application No. 5-145073). The conditions for using the adsorbent are as follows:
Preliminary tests may be performed as appropriate depending on the shape, required performance, and the like. The space velocity of the air to be treated in the apparatus (S
V) is usually 100 to 100,000 (h ^-1 ), preferably 100 to 20,000 (h ^-1 ). The causes of the increase in the contact angle can be roughly classified into (1) harmful gases (inorganic gas) such as SOx, NOx, and NH ₃ , (2) fine particles, and (3) HC (organic gas ) . result of the examination, a normal air impact to the concentration in the (ambient air in the usual clean room), (1) fine particles, (2) HC is large (Japanese Patent Application No. 3-341802). Therefore, in the present invention,
By controlling these fine particles and HC, the contact angle is prevented from increasing.

Next, the space to be cleaned, which is a closed space, will be described. This space is a space in which the base material and the substrate are stored or kept for a certain period of time in the process of the processing step, and an appropriate space can be used depending on the application field, the scale of the apparatus, the shape, and the like. For example, in a wafer stocker, it is a space in which a wafer case storing a wafer can be stored. next,
The gas circulation operating section for circulating gas will be described. This operating section is for purifying the gas in the above-mentioned space to be cleaned in the gas purifying section, circulating and returning the same. Any part of the working part can be used as long as it does not generate pollutants (particulate and gaseous pollutants), in particular HC, which increases the contact angle. Usually, a diaphragm pump using fluororesin packing is preferably used.

By this operation, the gas in the space to be cleaned is repeatedly treated by the gas purifying unit an appropriate number of times, so that the space to be cleaned is an ultra-clean space having a high degree of cleanness.
The space is stably maintained for a long time. The circulation of the gas in the space to be cleaned to the gas cleaning section can be determined by conducting a preliminary test as appropriate according to the application field, the scale of the apparatus, the shape, the type of the substrate or substrate, the required performance, and the like. For example, in the case of a stocker for semi-finished wafers, the gas purifying section circulates a volume (about 5 to 10 times the volume of the space to be cleaned) at which the gas in the space to be cleaned is almost completely replaced when the wafer is taken in and out.
Usually, since a very small amount of gas may be mixed in from the outside, it is preferable to perform appropriate circulation every several hours even when the wafer is not taken in and out (at night).

[0025]

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 A wafer stocker (storage) in a semiconductor factory for preventing an increase in a contact angle of a substrate or a substrate surface in a closed space according to the present invention.
FIG. 1 is a schematic configuration diagram showing an example applied to the present invention. In FIG. 1, reference numeral 1 denotes a class 10000 clean room, and outside air 9 before entering the clean room 1 is first processed by a coarse filter 10 and an air conditioner 11. Next, when the air enters the clean room 1, the dust is removed by the HEPA filter 12, and the class 1 in which the extremely low concentration HC coexists.
The air 13 has a concentration of 0000. That is, the ultra-low concentration HC mainly generated from a car or the like is filtered by the coarse filter 10,
Since it is not removed by the air conditioner 11 and the HEPA filter 12, it is introduced into the clean room 1.
The concentration of HC in the air 13 is 0.5 to 0.1 in non-methane HC.
8 ppm.

A stocker 15 according to the present invention is installed in the clean room 1 and stocks raw materials, semi-finished products, and product wafers. The stocker 15 mainly moves the space to be cleaned (stock portion) A, the gas purifying portion B that processes air in the space to be cleaned A, and the air in the space A to be cleaned to the gas purifying portion B, It is composed of a gas circulation operation section C for performing circulation processing. Each part will be described below. The space A to be cleaned is a stock (storage) space for wafers, and stocks raw materials, semi-finished products, and product wafers depending on the operation state of the manufacturing process. Gas purification section B
Consists of a hydrophilic adsorbent 4 _-1 , a hydrophobic adsorbent 4 _-2 , and a dust filter 5, and collects and removes the fine particles 16 contained in the air in the space A to be cleaned and the HC 17 which increases the contact angle. Do. The air in the space A to be cleaned, including the fine particles 16 and the HC 17 that increases the contact angle, is
And then circulated, the fine particles and HC
Is ultra-clean air (particulate concentration class 1 or less, non-methane HC 0.1
ppm or less) 19.

The circulating pump 18 circulates the air in the space A to be cleaned in the gas purifying section B, so that the space A to be cleaned becomes an ultra-clean space. The operation of the circulation pump 18 is performed immediately after the wafer is put in and taken out of the space A to be cleaned (stock part).
That is, since the air 2 in the clean room having a concentration of class 10000, in which HC that increases the contact angle coexists, enters the stock unit A by taking in and out of the wafer, immediately after the taking in and out of the wafer, the air volume 5 in the space A to be cleaned is reduced. It is performed so as to circulate 10 to 10 times the amount to the gas cleaning section B. Furthermore, even when no wafer is taken in and out (for example, at night), the circulation process is performed about once every several hours in the same manner, assuming that a very small amount of air 2 in the clean room is mixed. Reference numeral 20 denotes a timer for automatic operation for performing such an intermittent operation. In this way, a super-clean space is easily created in the space to be cleaned A, and the space A is stably maintained for a long time. 21 is the circulation pump 1
8 is a filter for preventing the harmful component from flowing back into the space A to be cleaned and being mixed in the case where a harmful component such as particulate matter which may affect the increase in the contact angle is generated.

The embodiment of the present invention in the case of removing the extremely low concentration HC in the air in a normal clean room has been described. Generally contaminates the substrate or substrate surface,
The substances that increase the contact angle are (1) SOx,
Noxious gases such as NOx, HCl, and NH ₃ , (2) fine particles, and (3) HC can be roughly classified. In N ₂ used in a clean room such as a semiconductor manufacturing plant or a liquid crystal manufacturing plant, the influence of fine particles and HC on the contact angle is large. That is, generally, SOx,
NOx, HCl, and NH ₃ have little effect on increasing the contact angle at normal air concentration levels. Therefore, an effect can be obtained by dust removal and HC removal. However, 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. 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 and an apparatus proposed by the present inventor to irradiate the harmful gas with ultraviolet rays and / or radiation to make the gas fine and to collect the fine particles (Japanese Patent Laid-Open No. Hei 4-243517). Or a method and an apparatus for collecting and removing harmful gases by contacting a harmful gas with ozone and then contacting it with a composite oxide catalyst having ozone decomposing ability and harmful substance adsorption ability (JP-A-6-190236, JP-A-6-205930) can be used in appropriate combination. In such a case, another known harmful gas removing material for collecting the harmful gas, for example, activated carbon,
An ion exchange resin or the like may be appropriately used in combination. As the activated carbon, an activated carbon to which an acid, an alkali, or the like is impregnated, or which is appropriately modified by a known method can be used. In this embodiment, the case where the medium is air has been described. However, it is needless to say that the present invention can be similarly carried out when fine particles or gaseous harmful components are contained as impurities in another gas such as nitrogen or argon.

Example 2 A glass substrate was stored in a stocker 15 using the present invention shown in FIG. 1, and the increase in the contact angle was examined. For comparison, the clean room air 2 was passed through the gas cleaning section shown in FIG. 1 in one pass, and the clean air was continuously exposed on a glass substrate housed in a 3 liter glass container. Examined. Operating conditions of clean room Cleanliness: Class 10000 Humidity: 40 to 50 RH% Temperature: 23 ° C Non-methane HC concentration: 0.6 to 0.8 ppm Stocker (cleaned space) volume: 100 liters

Adsorbent and SV in the gas purifying section: silica gel and fibrous borosilicate glass solidified in a filter shape using tetrafluoride resin as a binder, and SV is 2000 (h) each.
^-1 ), 10000 (h ^-1 ) Circulation pump: Polyfluoroethylene diaphragm pump Circulation volume: 20 liter / min Circulation is performed immediately after taking out the glass substrate for measurement in order to measure the contact angle of the glass substrate, and Intermittent operation was performed every three hours. Measurement of contact angle on glass substrate: water drop type contact angle meter

Results The exposure time of the glass substrate to air and the measured contact angle θ
Is shown in FIG. In FIG. 3, the results of exposing the treated air to a glass substrate housed in a glass container by passing a clean room air through the adsorbent in a single pass through the adsorbent of the present invention as indicated by-○-are shown in FIG. − ● −
Indicated by In addition, the circulation pump used for comparison was not operated (the gas purification section was not used), and the results obtained in the same manner are indicated by-■-. The frequency (lower limit of detection of the contact angle) at which the contact angle of the contact angle meter used could be examined was 3 to 4 degrees, and in the case of the present invention, the detection limit (↓) was initially shown. The concentration of fine particles at the outlet of the apparatus is class 10 or less (measuring device: light scattering type particle counter), and the concentration of non-methane HC is 0.1%.
It was 1 ppm or less (measuring device: gas chromatograph).

[0033]

According to the present invention, the following effects can be obtained. (1) By circulating the gas between the space to be cleaned and the gas purifying unit, (a) utilizing the high quality gas purified by the gas purifying unit for a long time in the space to be cleaned (effective Use). (B) Even if fine particles or gaseous harmful components that increase the contact angle enter the space to be cleaned by taking in or out of the space to be cleaned, only the permeated amount is collected by the gas cleaning unit.
Since it has only to be removed, effective processing can be performed. (C) Since the gas in the space to be cleaned is circulated to the gas cleaning unit and can be repeatedly processed, the space to be cleaned is an ultra-clean space free of fine particles and gaseous harmful components, and the burden on the gas cleaning unit is small. Therefore, an ultra-clean space that is stable for a long time was achieved. Almost all of the adsorption capacity of the adsorbent was effectively used.

(D) When the adsorbent used in the present invention is used in a single pass, the amount of the processing gas is large, and the performance is deteriorated due to the influence of moisture, but the life is shortened by the moisture. As they have already proposed, 30
(Dehumidification is performed in advance so as to be RH% or less). In the configuration of the present invention, once the treatment is performed, only the intrusion is required next, so that the individual dehumidifier is usually unnecessary. Also, depending on the field of use, the scale of the equipment (increase in size), and the conditions of the coexisting gas (use in an environment with a lot of moisture), even when a dehumidifier is provided, the amount of moisture is large compared to the conventional one-pass use. Since the number of drains is reduced, a small-sized dehumidifier is sufficient, the amount of drain is small, the apparatus is downsized, and the management becomes easy. (E) By using an ion exchanger as one of the adsorbents, an ionic substance can be removed simultaneously with the removal of the component that increases the contact angle according to the present invention, so that the field of application has been expanded. (2) From the above, the utility of the present invention using an adsorbent has been enhanced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of a wafer stocker using the apparatus of the present invention.

FIG. 2 is a schematic configuration diagram showing an example of a known device for preventing an increase in contact angle.

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

[Explanation of symbols]

1: Clean room, 2: Air in clean room, 3:
Dehumidifier, 4: adsorbent, 4 _-1 : hydrophilic adsorbent, 4 _-2 : hydrophobic adsorbent, 5: dust filter, 8: air knife device,
9: outside air, 10: coarse filter, 11: air conditioner, 1
2: HEPA filter, 13: air, 15: stocker,
16: fine particles, 17: HC, 18: circulation pump, 19:
Ultra-clean air, 20: timer, 21: filter, A: space to be cleaned, B: gas cleaning unit, C: gas circulation operation unit

Claims (2)

(57) [Claims] In a method for preventing an increase in the contact angle of the surface of a substrate or a substrate in an enclosed space, a gas containing at least hydrocarbons is treated so that the concentration of fine particles in the gas is 10 or less and the concentration of non-methane hydrocarbons is 0%. Cleaned by dust removal and adsorption treatment so as to have a concentration of 2 ppm or less, and the purified gas is ventilated into a closed space for accommodating a substrate or a substrate to circulate between the cleaning treatment and the closed space. Gas inside
The circulation device intermittently cleans and circulates
A method for preventing an increase in the contact angle of the surface of a substrate or a substrate in an enclosed space , wherein a backflow of gas before a purification treatment into the enclosed space is prevented. 2. An apparatus for preventing an increase in the contact angle of the surface of a substrate or a substrate in an enclosed space, for removing the enclosed space for accommodating the substrate or the substrate and the concentration of fine particles in a gas to a class 10 or less. A gas purifying device having a dust removing means and an adsorbing means for removing the non-methane hydrocarbon concentration until the concentration becomes 0.2 ppm or less, and circulating the gas in the closed space between the closed space and the gas purifying device. Gas circulation means, wherein the gas circulation means circulates the gas.
Circulation flow path and the flow from the enclosed space to the gas purifier
Road has intermittently operated circulation device and backflow prevention means
Contact angle increase prevention device substrate or substrate surface in the enclosed space, characterized in that that.