JP2002224632A - Method and apparatus for cleaning surface of substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning apparatus and a cleaning method by which the tainted surface of a substrate can be cleaned. SOLUTION: This method for cleaning the tainted surface of the substrate 3 comprises a step to apply high-frequency energy 4 to the tainted surface of the substrate 3 and a step B to collect/remove the contaminants generated from the surface of the substrate by the application of high-frequency energy. The step B can be carried out by using a contaminant collecting/removing means in which at least one of an adsorbing material, an ion exchange fiber, a photocatalyst and a photoelectron is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to cleaning a substrate surface, and more particularly to a method and an apparatus for cleaning a substrate surface such as a wafer or glass in a clean room or the like.

[0002]

2. Description of the Related Art As a conventional technique, an outline of a contamination problem in a process of manufacturing a silicon semiconductor substrate will be described.
Purification of air in a clean room will be described with reference to the schematic configuration diagram of FIG. In FIG. 7, first, coarse particles are removed from the outside air 21 by a pre-filter 22, and then the temperature and humidity are adjusted by an air conditioner 23.
Dust is removed. Next, a HEPA filter (high-performance filter) 26 installed on the ceiling of the clean room 25
, Fine particles are removed, and the clean room 25 is maintained in a class of 100 to 1,000. Here, reference numeral 27-
1, 27-2 are fans, and the arrows indicate the flow of air. The conventional air cleaning in a clean room is intended to remove fine particles, and is configured as shown in FIG. 7. Such a configuration is effective for removing fine particles, but removes gaseous harmful components. Has no effect. Also,
In a large room type clean room as shown in FIG. 7, for example, there is a problem that the cost is too high for advanced cleaning of classes 1 to 10.

[0003] In the future, in the semiconductor industry, the quality and precision of products are increasing more and more. With this, not only fine particles (particulate matter) but also gaseous substances are involved as pollutants in addition to fine particles. In other words, removal of fine particles has been sufficient in the past, but now gaseous substances (gaseous harmful components)
As described above, it is important to also remove. This is because, in the conventional clean room dust filter (eg, HEPA, ULPA filter) 26 shown in FIG. 7, only the fine particles are removed, and gaseous harmful components from the outside air are introduced into the clean room without being removed. This is because Such gaseous harmful substances include, for example, automobile exhaust gas that is introduced into a clean room,
Hydrocarbons (HC) caused by degassing (gas generation) from polymer resin products widely used as consumer products
And a basic (alkaline) gas such as NH ₃ and amine.

[0004] Of these, hydrocarbons (H.C.) need to be removed as those having extremely low concentrations in ordinary air (room air and outside air) as gaseous harmful components cause contamination. Also, recently, degassing from polymer resins in cleanroom components, manufacturing equipment, and tools used has become a problem as a source of hydrocarbons (HC). These gaseous substances also pose a problem when they are generated during the operation in the clean room. That is, as a cause of the gaseous substance, a gaseous substance introduced from the outside air in a normal clean room (a gaseous substance in the outside air is introduced because a gaseous substance cannot be removed by a particle removal filter of a clean room). In addition, since the gaseous substances generated in the clean room are added, the concentration of the gaseous substances in the clean room becomes higher than that in the outside air, which may contaminate the semiconductor substrate.

That is, if the above-mentioned contaminants (fine particles, gaseous harmful components) adhere to the surface of the semiconductor substrate, the fine particles become
The circuit (pattern) on the substrate surface is broken or short-circuited to cause a defect. In addition, when a hydrocarbon (HC) as a gaseous substance adheres to the surface of a semiconductor (substrate), it causes an increase in the contact angle and affects, for example, the affinity (fit-in) between the substrate and the resist. When the affinity deteriorates, the film thickness of the resist is adversely affected, or the adhesiveness between the substrate and the resist is adversely affected. In addition, hydrocarbons (H.
C. ) Also has the problem of causing deterioration of the breakdown voltage (reduction in reliability) of the oxide film on the surface of the semiconductor substrate. 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) contaminant adheres to the substrate surface, the surface repels water and becomes hard to wet. Then, the contact angle with the water droplet on the substrate surface increases. Therefore, the contamination degree is high when the contact angle is large, and low when the contact angle is small.

In addition, NH ₃ causes the production of an ammonium salt and the like, and causes clouding (defective resolution) on a semiconductor substrate. For these reasons, these gaseous contaminants as well as fine particles reduce the productivity (yield) of semiconductor products. In particular, since the above-mentioned gaseous substances as gaseous harmful components are used due to the above-mentioned generation, and recently, by increasing the circulation of clean room air from the viewpoint of energy saving, the concentration of organic gaseous substances in the clean room is reduced. It is concentrated and has a considerably higher concentration than the outside air,
Attaches to substrate and contaminates the surface. On the other hand, energy saving and cost saving technologies are becoming important. It is proposed that mini-environment, that is, “local environment surrounded by an enclosure for isolating products from contamination and humans” is effective against such issues, and technological development for that purpose becomes important. I have. In the current mini-environment, for example, when transporting semiconductor substrates, there is a system to prevent contamination from clean room air and people by storing the substrates in a transparent plastic sealed container such as polycarbonate (PC). It is proposed to be effective.

However, in the system using the plastic container, technical problems such as gas generation from the container material, measures against sudden dust generation from the inside, and periodic cleaning of the container have been pointed out. . In order to cope with such a problem, the present inventors have proposed local cleanliness as a mini-environment, and have proposed various types of cleanliness methods using photoelectrons or photocatalysts as a technology for that purpose. For example, 1) as a cleaning method using photoelectrons (removal of particulate matter): JP-B-3-5859, JP-B-6-749
No. 09, No. 8-211, No. 7-121367
No., and the like. 2) As a cleaning method (removal of gaseous harmful components) using a photocatalyst: JP-A-9-168722, JP-A-9-2050
No. 46, and the like. 3) As a combined use method of photoelectrons and photocatalysts (simultaneous removal of particles and gas), there is JP-A-1-266864 and the like.

[0008]

Any of the above-mentioned conventional cleaning methods is a proposal for a method of removing contaminants in a space, for example, a space in which a substrate is placed. There is a problem that a small amount of contaminants such as organic substances adhere to the wafer surface. In view of such circumstances, an object of the present invention is to provide a method and an apparatus for cleaning a contaminated substrate surface.

[0009]

In order to solve the above problems, the present invention provides a method for cleaning a contaminated substrate surface, wherein high frequency energy is applied to the substrate surface, and the contaminated substrate surface is generated from the substrate surface by the application. Pollutants are collected and removed. In the cleaning method, the collection and removal of contaminants generated from the substrate surface is performed using at least one of contaminant collection and removal means using an adsorbent, ion exchange fibers, a photocatalyst, or photoelectrons. be able to. Further, according to the present invention, in an apparatus for cleaning a contaminated substrate surface, a storage section for the substrate, a high-frequency generator for applying high-frequency energy to the substrate surface, and a contaminant generated from the substrate surface are collected. -It has a generated contaminant removal section for removal. In the cleaning device, the generated contaminant removal unit may be configured by at least one of contaminant collection and removal means using an adsorbent, ion exchange fibers, a photocatalyst, or photoelectrons.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The cleaning of the substrate surface according to the present invention is based on the following five findings in a clean room. (1) Regarding the contamination of the semiconductor substrate, the response of fine particles has been studied so far. However, the influence of gaseous substances such as hydrocarbons (organic substances) on the substrate will increase in the future.
That is, when the gaseous substance adheres to the substrate, the productivity of the device is greatly reduced (the yield is reduced).

(2) In a clean room, mini-environment will be important in the future in terms of energy saving and cost saving. That is, contamination is prevented by storing the substrate in a plastic box and isolating it from the clean room air and people. Currently, the mini-environment stores substrates in a plastic (eg, polycarbonate) box,
The transport method is considered to be effective. However,
The box is made of plastic, so DOP, DBP
(Gas generation). And the generated gas itself adheres to the semiconductor substrate,
This has an adverse effect (decrease in yield). Further, the gaseous contaminants have a function of reducing the yield of the device or accelerating the oxidation of the substrate surface.

In the future, it is said that the oxidation of the substrate surface becomes important as a cause of contamination in addition to the direct contamination of the gaseous substances (Ultra Clean Technology,
Vol. 10, No. 1, p. 1). That is, in the future, it will be important to control (prevent) the formation of a natural oxide film on the substrate surface. That is, in the future, with the progress of device miniaturization, control of the structure of the silicon surface on the atomic scale becomes increasingly important. Since the natural oxide film has a large effect on the controllability of the ultra-thin gate oxide film thickness, inhibition of silicide reaction, increase in contact resistance, inhibition of epitaxial growth, etc., a control technology (prevention technology) is required in the future. . In other words, mild means (cleaning means that does not damage the substrate is required.
_It is important to remove (prevent) organic substances on the substrate in a method that does not perform ( ₃₎ generation or short-wavelength UV irradiation.

(3) For this reason, an effective method (apparatus) for removing gaseous contaminants (eg, organic substances) attached to the substrate is as follows.
It will be needed in the future. (4) The gaseous contaminants attached to the substrate are vaporized (desorbed) when the substrate is irradiated with a high frequency wave, for example, a microwave. The mechanism for desorbing organic substances on the substrate surface is considered as follows. That is, moisture is involved in the organic matter attached to the substrate. For example, a model of the organic matter attached to the substrate is considered as shown in FIG. 6, and therefore, the moisture layer 17 is vibrated by microwave irradiation. As a result, the organic matter 18 is desorbed to the upper space. (5) Since the desorbed gaseous pollutants are gaseous,
The gaseous pollutant is effectively removed by providing any one of the collecting and removing means using activated carbon, ion exchange fiber, photocatalyst, and photoelectron near the microwave irradiation section.

Next, each configuration of the present invention will be described in detail. The high frequency wave used in the present invention may be any one that desorbs (vaporizes) contaminants adhering (adsorbed) on a substrate such as a wafer surface by applying high frequency energy. It can be used as appropriate depending on the shape and required specifications. As such a high frequency, there is a microwave, which can be suitably used. The microwave is an electromagnetic wave of 1000 Mc to 1000 kmc, and is implemented by irradiating the microwave on the substrate. As such a microwave, generally, 2,450 MH
There is an electromagnetic wave of z.

The microwave is generated by a magnetron, a klystron, a traveling wave tube, a retrograde wave tube, or the like. Among them, the magnetron is preferably used because it can be easily used, for example, the overheating of a substrate such as a wafer can be controlled by the amount of electricity. The microwave energy oscillating unit may be installed at a location where microwaves are uniformly irradiated on the surface of the wafer to be cleaned in the wafer storage space. The position is an upper portion and a side portion of the wafer storage space, and can be appropriately determined by an installation form of a cleaning container for a wafer to be cleaned. Usually, it is preferable to install the device so as to face the surface of the wafer since it works uniformly. In other words, it is preferable to act uniformly so that the surface of the wafer can be uniformly cleaned (contaminants are evenly removed).

FIGS. 1 (a) and 1 (b) show an example of installation on an upper portion and a side portion, respectively. In FIG. 1 (a), 1 is a wafer cleaner, 2 is a wafer to be cleaned, A is a wafer storage (installation) space (microwave irradiation section), and B is a contaminant generated from the wafer (described below). Removing part)
Denotes a microwave generator, and M denotes a magnetron that generates a microwave. Also, in FIG.
The same symbols as in (a) have the same meaning. Next, a means for collecting and removing gaseous pollutants vaporized by microwave energy from the substrate will be described. The removing means may be any means for collecting and removing vaporized gaseous (in gas) contaminants adjacent to the substrate installation portion to which the microwave is applied. Can be used as appropriate.

Next, the contaminant removing means will be described. (1) Means of using a trapping material The means of using a trapping material is such that the generated gas is NOx, SOx, H
It is suitable for the case of an acidic gas such as Cl or HF, or alkaline such as ammonia or amine. The collecting material may be any material that efficiently collects the generated gas to a low concentration. Such adsorbents include silica gel, zeolite, alumina, activated carbon, or ion-exchange fiber as an adsorbent. Among them, activated carbon and ion-exchange fiber are effective (high collection efficiency, low pressure loss). Etc.). As the activated carbon, an impregnated carbon such as an acid or an alkali can be used as appropriate according to a method of combining a trapping component (a kind of a target gas) or an ion exchange fiber. The shape of the trapping material can be used in an appropriate shape,
Generally, a fibrous or honeycomb shape is preferred because of its low pressure loss.

As for the ion-exchange fiber, it is possible to use a cation-exchanger or anion-exchanger or a cation-exchange group and an anion-exchanger on the surface of a support such as a natural fiber or a synthetic fiber or a mixture thereof. An ion exchanger having both groups is supported, and as a method, the support may be directly supported on a fibrous support, a woven fabric,
After forming into a knitted or flocked form, it can be supported thereon. In any case, it suffices that the fibers finally support the ion exchanger. Used in the present invention,
As a method for producing the ion-exchange fiber, an ion-exchange fiber produced using a graft polymerization, particularly a radiation graft polymerization method, is preferable. This is because various materials and shapes can be used. Now, as the natural fiber, wool, silk, etc. can be applied, and as the synthetic fiber, one made of a hydrocarbon polymer, one made of a fluorine-containing polymer, or polyvinyl alcohol, polyamide, polyester , Polyacrylonitrile, cellulose, cellulose acetate and the like can be applied.

Examples of the hydrocarbon polymer include aliphatic polymers such as polyethylene, polypropylene, polybutylene and polybutene; aromatic polymers such as polystyrene and poly-α-methylstyrene; and alicyclic polymers such as polyvinylcyclohexane. A polymer or a copolymer thereof is used. Further, as the fluorine-containing polymer, polytetrafluoroethylene, polyvinylidene fluoride, ethylene-tetrafluoroethylene copolymer, ethylene tetrafluoride-propylene hexafluoride copolymer, vinylidene fluoride-hexafluoride A propylene copolymer or the like 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 large mechanical strength,
Any material can be used as long as it is a material that has a small effect on falling off of fiber waste, generation and heat, and can be appropriately selected in consideration of the intended use, economy, effect, etc. Usually, polyethylene is generally used, and polyethylene or polyethylene and polypropylene are generally used. Complexes with are especially preferred.

Next, the cation exchanger is not particularly limited, and various cation exchangers or anion exchangers can be used. For example, taking the case of cation exchange as an example, a carboxyl group, a sulfonic acid group, a phosphate group,
A cation exchange group-containing substance such as a phenolic hydroxyl group, an anion exchange group-containing substance such as a primary to tertiary amino group or a quaternary ammonium group, or an ion exchange having both the positive and negative ion exchange groups. Body. Specifically, for example, acrylic acid, methacrylic acid,
Styrene compounds such as vinylbenzenesulfonic acid, styrene, halomethylstyrene, acyloxystyrene, hydroxystyrene, aminostyrene, vinylpyridine,
-Methyl-5-vinylpyridine, 2-methyl-5-vinylimidazole, and acrylonitrile are graft-polymerized, and then reacted with chlorosulfonic acid, sulfonic acid or the like, if necessary, to obtain a fibrous material having a cation or anion exchange group. An anion exchanger is obtained.

[0021] These monomers are used on 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. Graft polymerization may be performed. In this way, ion exchange fibers are manufactured. The diameter of the ion exchange fiber is 1 to 1000 μm, preferably 5 to 20 μm.
It is 0 μm, and can be appropriately determined depending on the type of fiber, application, and the like. The use of cation exchange groups and anion exchange groups among these ion exchange fibers can be determined depending on the type and concentration of the component to be removed in the target processing gas. For example, the component to be removed may be measured and evaluated in advance, and the type and amount of the ion-exchange fiber corresponding thereto may be used. Those having a cation exchange group (cation exchanger) when removing an alkaline gas, those having an anion exchange group (anion exchanger) when removing an acidic gas,
In the case of a mixed gas of both, fibers having both positive and negative exchange groups can be used.

As a method of flowing gas into the ion exchange fiber,
It is effective to flow perpendicular to the filter-like ion exchange fibers. The flow rate of the gas flowing into the ion-exchange fiber can be determined as appropriate by conducting a preliminary test. However, since the fiber has a high removal rate, the SV is usually 1000 to 100,000 (h).
^-1 ) can be used. As the ion exchange fiber, as previously proposed by the present inventors, it is preferable to use a fiber produced by radiation graft polymerization, since the effect is particularly high, and it is possible to appropriately use the ion exchange fiber (Japanese Patent Publication No. 5-9123,
JP-B 5-67325, JP-B 5-43422 and JP-B 6-24626. The ion-exchange fiber is effective in collecting ionic substances (components), and the acidic gas and alkaline gas targeted in the present invention are considered to be ionic substances.・ Can be removed.

In particular, the ion exchange filter (fiber) produced by radiation graft polymerization has a wide ion exchanger (anion and / or cation exchanger) because the irradiation of the support is uniformly performed to the inner part. Since it is firmly (strongly) added to the area (added at high density), the exchange capacity is large, and there is an effect that low-concentration ionic substances can be efficiently removed at a high speed, and it is practically effective. is there. In addition, the production by radiation graft polymerization has advantages such as being able to be formed into a shape close to the product, being able to be performed at room temperature, being able to be performed in the gas phase, being able to increase the graft ratio, and being able to produce an adsorption filter with less impurities. For this reason,
It has the following features. The ion exchange fiber (adsorption function part) is uniformly added to the ion exchange fiber produced by the graft polymerization by irradiation with radiation (the addition density is high), so that the adsorption speed is high and the adsorption amount is large. Low pressure loss. Further, depending on the usage (required specifications), an adsorbent for glass and a fluororesin already proposed by the present inventor, for example, a glass fiber filter using a fluororesin as a binder can also be suitably used. This filter is effective for simultaneously removing gaseous organic matter and particulate matter (fine particles). (Patent No .: 2582706).

(2) Means Using a Photocatalyst Means using a photocatalyst is suitable when the generated gas is an organic substance (HC) such as a phthalic acid ester. C. Can be decomposed to a low concentration. The photocatalyst is excited by light irradiation, C.
Can be decomposed, that is, H. C. Is decomposed into CO
Any material such as ₂ or H ₂ O can be used as long as it can be converted into a form that is stable with respect to the substrate. Usually, a photocatalyst is preferable because a semiconductor material is effective, easily available, and has good workability. In terms of effectiveness and economy, Se, Ge, S
i, Ti, Zn, Cu, Al, Sn, Ga, In, P,
As, Sb, C, Cd, S, Te, Ni, Fe, Co,
Any of Ag, Mo, Sr, W, Cr, Ba, Pb,
Alternatively, these compounds, alloys, or oxides are preferable, and these are used alone or in combination of two or more.

For example, the elements are Si, Ge, Se,
Compounds include AlP, AlAg, GaP, AlSb,
GaAs, InP, GaSb, InAs, InSb, C
dS, CdSe, ZnS, MoS₂, WTe₂, Cr₂
Te₃, MoTe, Cu₂S, WS₂As an oxide
Is TiO₂, Bi₂O₃, CuO, Cu₂O, Zn
O, MoO₃, InO₃, Ag₂O, PbO, SrTi
O₃, BaTiO₃, Co ₃O₄, Fe₂O₃, NiO
and so on. Depending on the application destination, sinter the metal material
A photocatalyst can be formed on the surface. In this example
The Ti material is fired at 1000 ° C._Two
There is a photocatalyst that forms chromium (Japanese Patent Application No. 9-273302).
issue). In addition, in order to improve the photocatalytic action,
Pt, Ag, Pd, RuO_Two, CO_ThreeO_FourAdd a substance like
It can also be used. The addition of the substance will affect the photocatalyst
According to H. C. This is preferable because the decomposition action is promoted. this
Can be used alone or in combination. Through
Usually, the amount added is 0.01% by weight to 10% by weight based on the photocatalyst.
%, Depending on the type of additive substance and required performance
Preliminary experiments can be performed to select an appropriate concentration.

As a method of addition, well-known means such as an impregnation method, a photoreduction method, and a kneading method by a sputter deposition method can be appropriately used. The installation form of the photocatalyst can be fixed to the air where the vaporized air flows, fixed to the wall surface, or suspended in the air. For fixing the photocatalyst, the photocatalyst is formed into a plate, cotton, line, fiber, mesh, honeycomb,
It may be coated on a suitable material such as a film, a sheet, or a fiber, or wrapped or sandwiched, and fixed in the unit. For example, ceramic, metal, fluororesin, glass materials, sol-gel method, sintering method,
Well-known additional means such as a vapor deposition method and a sputtering method can be used as appropriate. In general, a fibrous, net-like, or honeycomb-like shape is preferred because of its low pressure loss.

An example is the addition of TiO ₂ to glass fibers by the sol-gel method. Further, the addition of a photocatalyst to the surface of a light-transmitting linear article already proposed by the present inventors (Japanese Patent Laid-Open No.
-256089) can also be used as appropriate. Further, integration with a light source already proposed by the present inventor (JP-A-9-2050)
No. 46) can also be used as appropriate. Next, any light source that irradiates the photocatalyst with light may be used as long as the photocatalyst has a photocatalytic action by irradiating the photocatalyst with light.
That is, H. by photocatalysis. C. The decomposition of can be performed by irradiating the photocatalyst with the gas to be treated while irradiating the photocatalyst with light in a light absorption range (wavelength range) determined by the type of the photocatalyst.

An example of the main light absorption region of the photocatalyst is as follows. Si: <1,100 (nm), Ge: 1,825 (n
m), Se: <590 (nm), AlAs: <517
(Nm), AlSb: <827 (nm), GaAs: <
886 (nm), InP: <992 (nm), InS
b: <6,888 (nm), InAs: <3,757
(Nm), CdS: <520 (nm), CdSe: <7
30 (nm), MoS ₂ : <585 (nm), ZnS:
<335 (nm), TiO ₂ : <415 (nm), Zn
O: <400 (nm), Cu ₂ O: <625 (nm),
PbO: <540 (nm), Bi 2 O 3: <390 (n
m). The light source has only to have a wavelength in the light absorption region of the photocatalyst, and a known light source can be used as appropriate. Sunlight or ultraviolet lamps can be used. UV sources are usually mercury lamps,
A hydrogen discharge tube, a xenon discharge tube, a Lyman discharge tube, or the like can be used as appropriate. Examples of the light source include a germicidal lamp, a black light, a fluorescent chemical lamp, a UV-B ultraviolet lamp, and a xenon lamp, which can be used.

Among them, a germicidal lamp (main wavelength: 254n)
m) is preferable because the effective irradiation light amount to the photocatalyst can be increased, the photocatalytic action is enhanced, ozone-free, easy installation is possible, inexpensive, easy to maintain, manage and maintain, and high performance. . Irradiation amount to the photocatalyst by the light source is 0.05~50mW / cm ^2, preferably from 0.1 to 10 MW / cm ^2. H. C. Can be collected by the use of an adsorbent, for example, activated carbon. However, the use of an adsorbent causes the problem of adsorption capacity and breakthrough (when the generated gas concentration is high, the adsorption capacity is saturated in a short time. It is troublesome, and there is the problem of secondary contamination due to the spillage of the collected matter due to breakthrough. On the other hand, the photocatalyst is H. C. Is decomposed, so that it can be used stably for a long time (because HC has no accumulation by adsorption). C.
It is suitable for the removal of.

(3) Means Using Photoelectrons Means using photoelectrons are suitable in the case where particulate matter (fine particles) is generated. In addition, this means is suitable for collecting polar substances such as SO ₂ and phthalic acid esters as gaseous pollutants. This means that in the means using photoelectrons, the gas is converted into particles by ion nucleation by the irradiation ultraviolet rays in the ultraviolet irradiation of the photoelectron emitting material,
This is because they are charged and collected by photoelectrons. Since this means uses ultraviolet light, when used in combination with the above-mentioned means using a photocatalyst, H.O. C. For removal, H. C. Since removal of the gas dyeing substances, such as or SO ₂ is added, the type of the cleaning substrate (type of substances generated by microwave irradiation), depending on the required specification, a preferred form. This means uses a method using photoelectrons already proposed by the present inventors (UV / photoelectron method, for example, Japanese Patent Publication No. 6-74909, Japanese Patent Publication No. 7-121369, Japanese Patent Publication No. 8-2211, and Japanese Patent Publication No. 8-223393). No., Patent No. 262
No. 3290) can also be used as appropriate.

Next, the configuration of the present means will be described. The removal using photoelectrons includes a photoelectron emission material, an ultraviolet lamp, an electrode material for an electric field for photoelectron emission, and a charged particle collection material, and removes generated particles (particulate matter). The photoelectron emitting material may be any material that emits photoelectrons when irradiated with ultraviolet rays, and the smaller the photoelectric work function, the better. In terms of effectiveness and economy, Ba,
Sr, Ca, Y, Gd, La, Ce, Nd, Th, P
r, Be, Zr, Fe, Ni, Zn, Cu, Ag, P
t, Cd, Pb, Al, C, Mg, Au, In, Bi,
Nb, Si, Ti, Ta, U, B, Eu, Sn, P, W
Or a compound, an alloy, or a mixture thereof is preferable, and these are used alone or in combination of two or more. As the composite material, a physical composite material such as amalgam can be used.

For example, as the compound, oxide, boride
And carbides, and oxides include BaO, SrO, Ca
O, Y_TwoO_Five, Gd_TwoO_Three, Nd_TwoO_Three, ThO_Two, ZrO_Two,
Fe _TwoO_Three, ZnO, CuO, Ag_TwoO, La_TwoO_Three, Pt
O, PbO, Al_TwoO_Three, MgO, In_TwoO_Three, BiO, N
bO, BeO, and the like.
B ₆, GdB₆, LaB_Five, NdB₆, CeB₆, EuB₆,
PrB₆, ZrB_TwoEtc., and as a carbide
Is UC, ZrC, TaC, TiC, NbC, WC, etc.
There is. As alloys, brass, bronze, phosphor bronze,
Alloy of Ag and Mg (Mg is 2 to 20 wt%), Cu and
Alloy with Be (Be is 1 to 10 wt%) and Ba and Al
An alloy of Ag and Mg can be used.
Gold, alloys of Cu and Be and alloys of Ba and Al are preferred.
New Oxide heats only the scrap metal surface in air, or
Alternatively, it can be obtained by oxidation with a chemical.

Further, as another method, it is possible to obtain an oxide layer which is stable for a long time by heating before use to form an oxide layer on the surface. As an example, an oxide film can be formed on the surface of an alloy of Mg and Ag in water vapor at a temperature of 300 to 400 ° C., and this oxidation is stable over a long period of time. In addition, a substance that emits photoelectrons can be used in addition to another substance. As an example of this, there is a material obtained by adding a substance capable of emitting photoelectrons to an ultraviolet-transparent substance (Japanese Patent Publication No. 7-9309).
No. 8, JP-A-4-243540). There is integration with an ultraviolet source described later, for example, addition of a photoelectron emitting material to the surface of an ultraviolet lamp (Japanese Patent Application Laid-Open No. 4-243540). Since it becomes compact by integration, it is preferable depending on the type of application box. Further, it can be integrated with a photocatalyst (eg, TiO ₂ described later) (Japanese Patent Application Laid-Open No. 9-294919). In this mode, the photocatalyst can stabilize the photoelectron emitting material for a long time (can be removed even if there is a substance affecting the photoelectron emitting material) and can remove coexisting gaseous pollutants.
It is preferable depending on the use destination (type of device, required performance).

As will be described later, the shape and structure of the photoelectron emitting material differ depending on the shape and structure of the device (cleaning knit), desired effects, and the like, and can be determined as appropriate. The irradiation source for the photoelectron emitting material from the photoelectron emitting material may be any source that emits photoelectrons upon irradiation, and ultraviolet light is usually preferred. Any kind of ultraviolet rays may be used as long as the photoelectron emitting material emits photoelectrons by irradiation. As the ultraviolet light source, any one that emits ultraviolet light can be used, but a mercury lamp, for example, a germicidal lamp is preferable in terms of compactness. Next, the positions and shapes of the ultraviolet light source, the photoelectron emitting material, the electrode, and the charged particle collecting material will be described. These are installed around the ultraviolet light source together with the above-mentioned photocatalyst as required according to the required performance, and when integrated as a cleaning unit for a gas containing harmful gases and fine particles, they become compact, so that they are practically effective for maintenance (maintenance). is there.

The position and shape of the photoelectron emitting material may be any as long as they can be installed so as to surround the ultraviolet light emitted from the ultraviolet light source (to increase the irradiation area). Usually, ultraviolet rays from an ultraviolet ray source are radially emitted in the circumferential direction, so that any ultraviolet rays can be installed so as to surround the ultraviolet rays. The emission of photoelectrons from the photoelectron emitting material is effective by irradiating ultraviolet light under an electric field. The position and shape of the electrode for this purpose can be any as long as an electric field (electric field) can be formed between the electrode and the photoelectron emitting material. The electrode material and its structure may be those used in a known charging device. Any electrode material can be used as long as it is a conductor, such as tungsten, SUS or Cu-
There are Zn wire, rod shape, net shape, and plate shape. These are used singly or in combination of two or more kinds so that an electric field can be formed in the vicinity of the photoelectron emitting material (JP-A-2-303557).
issue). As a material for collecting charged fine particles (dust collecting material), various electrode materials such as a dust collecting plate and a dust collecting electrode in an ordinary charging device and an electrostatic filter system are generally used, but such materials as a steel wool electrode and a tungsten wool electrode are used. A wool-like structure is also effective. Electrec materials can also be suitably used.

The suitable combination of the photo-emissive material, the electrode material, and the material for collecting the charged fine particles is appropriately determined according to the shape, structure, required performance, economy, etc. of the surface cleaning device (space to be cleaned) of the present invention. What is necessary is that any contaminant such as fine particles present in the space to be cleaned can be quickly moved into the removing means by providing the removing means using photoelectrons in the space. The position and shape of the photoelectron emitting material and the electrode surround the ultraviolet light source, and the ultraviolet light source, the photoelectron emitting material, the electrode, and the charged fine particle collecting material can be integrated, the ultraviolet light emitted from the ultraviolet light source is effectively used, and In order to effectively perform emission and charging / collection of fine particles by the photoelectrons, it can be determined by a preliminary test or the like in consideration of the shape, effect, economy, and the like of the box. For example, when a rod-shaped (cylindrical) ultraviolet lamp is used, ultraviolet rays are radially emitted in the circumferential direction. The amount increases.

When a large amount of particulate matter is generated due to the high-frequency action on the substrate, a dust removing filter can be used as appropriate in addition to the means using photoelectrons. Such filters include electrostatic filters, HEPA filters, ULPA
There are filters and medium performance filters. It is preferable that the generated contaminant removing means be installed as a cleaning unit (integrated shape) adjacent to a high-frequency operating portion on the substrate, because the apparatus becomes compact and maintenance is simplified. The means for removing the generated contaminants can be selected according to the type of the substrate to be cleaned (the type of generated contaminants), the scale of the apparatus, the required specifications, and the like, and can be appropriately determined by performing a preliminary test. Since the contaminant removing means using the adsorbent generally uses a means such as a fan as a rotating power unit for introducing the processing gas to the adsorbent, the generation of gas or particulate matter contaminants from the part is reduced. Accompany. Therefore, in such a case, the contaminant removing means (removal filter) is appropriately combined.

[0038]

The present invention will be described below in more detail with reference to examples. Embodiment 1 FIG. 2 is a schematic configuration diagram showing a cleaner 1 for wafers (particularly, organic substances) contaminated in a clean room. The purifier 1
Is composed of a storage space (microwave irradiation part) A for the wafer 2 to be cleaned and a means (removal part) B for removing generated substances for processing the generated gas 3 from the wafer 2. The wafer 2 to be cleaned is placed in the microwave irradiator A, and the surface of the wafer 2 is irradiated with microwaves 5 oscillated from the microwave generator 4 from above.

The organic substance 3 as a gaseous contaminant generated (desorbed) from the surface of the wafer 2 is introduced into a removing section B composed of an ultraviolet lamp 6 and a photocatalyst 7, and activated by the irradiation of ultraviolet light from the ultraviolet lamp 6. By the action of the converted photocatalyst 7, it is rendered harmless to a low molecular weight gas such as CO ₂ . Reference numerals 8-1 and 8-2 denote airflows caused by a temperature difference between the upper and lower sides due to irradiation of the ultraviolet lamp 6, and the generated airflows sequentially introduce the generated organic substances 3 into the removing section B, where they are decomposed and processed. The airflow 8-1 is clean air. The main removal unit B is a cleaning unit that surrounds the photocatalyst 7 with the ultraviolet lamp 6 at the center, and the unit can be easily attached (removed) to the microwave irradiation unit A, so that maintenance can be performed easily. This is a feature of the surface cleaning system of the present invention. In this embodiment, the photocatalyst 7 is TiO ₂ / metal, and the ultraviolet lamp 6 is a germicidal lamp.

Embodiment 2 FIG. 3 shows a case where the organic matter 3 and the particulate matter 9 are present in the generated gas in the embodiment 1. The organic substance 3 and the particulate matter 9 as the generated gas are removed by a removing unit (cleaning unit) B including the ultraviolet lamp 6, the photocatalyst 7, the photoelectron emitting material 10, and the electrode 11. Removal part B
In addition, the particulate matter 9 introduced by the airflow 8-2 is charged by photoelectrons emitted by the photoelectron emitting material 10 irradiated with ultraviolet rays emitted from the ultraviolet lamp 6. Then, the charged particles are collected by the electrode 11. On the other hand, the organic substance 3 is decomposed and treated by the photocatalyst 7 as described in FIG. In this way, the organic substance 3 and the particulate matter 9 are treated in the removing section B, and the airflow 8-1 becomes clean air. FIG.
2, the same reference numerals as those in FIG. 2 have the same meaning. The photocatalyst 7 of this example is TiO ₂ / metal, the ultraviolet lamp 6 is a germicidal lamp, the photoelectron emitting material 10 is Au coating / TiO ₂ , and the electrode 11 is Al
Plate (700 V / cm).

Embodiment 3 FIG. 4 shows an embodiment 2 in which the removing section B is composed of an adsorbent and a dust filter. Next, the configuration of the removing unit B will be described. The removing unit B is a fan 14 for introducing the gas generated from the adsorbent 12, the dust filter 13, and the surface of the wafer 2 to the removing unit B, and prevents the backflow of contaminants (gas and particles) generated from the fan. And a backflow prevention filter 15. The organic matter 3 and the particulate matter 9 generated from the surface of the wafer 2 are introduced into the removal part B by the fan 14.

Here, the organic matter 3 is collected by the adsorbent 12, while the particulate matter is collected and removed by the dust filter 13. 8-1 and 8-2 are air flows generated by the operation of the fan, and 8-1 is clean air as described above. The backflow prevention filter 15 serves to prevent gaseous pollutants and particulate matter generated by the operation of the fan 14 from entering the microwave irradiation section A. 4, the same symbols as those in FIGS. 2 and 3 indicate the same meanings. The adsorbent 12 of this example is activated carbon, the dust filter is an ULPA filter,
The backflow prevention filter 15 is a fiber filter of a fluororesin binder already proposed by the present inventors. (Patent No .: 2582706).

Example 4 In a clean room, the surface of a wafer contaminated with an organic substance (organic gas) was cleaned using the wafer purifier shown in FIGS. 1) Wafer to be cleaned; 8-inch wafer contaminated with organic matter (adhesion amount: 1.5 ng / cm ² ) in a class 10 clean room 2) Wafer cleaner; (2-1) Means for removing generated substances using photocatalyst Purifier structure and size: 60 liters capacity with the structure shown in FIG. 2 Photocatalyst: TiO ₂ is added on SUS (fine mesh) Ultraviolet lamp: germicidal lamp (254 nm), 6 W High frequency: microwave, 200W

(2-2) Purifier for removing generated substances using an adsorbent Structure and size: 60 liters in volume with the structure shown in FIG. 4 Adsorbent: activated carbon Dedusting filter: HEPA filter Filter for preventing backflow : Glass fiber filter of fluororesin binder (filter-like) High frequency: microwave, 200 W 3) Measurement of organic substances on wafer surface; overheating desorption, GC / M
S method

Results After the generated substance removing section was activated, the wafer surface was irradiated with microwaves, and the concentration of organic substances adhering to the wafer surface at that time was measured. (1) Purifier of means for removing generated substances using a photocatalyst FIG. 5 shows the relationship between the microwave irradiation time and the organic substance concentration on the wafer. In FIG. 5, ○ indicates the result of the present invention. (2) Purifier in which generated substances are removed using an adsorbent In FIG. 5, △ indicates the result of the present invention, and the result of the same test as described above. In FIG. 5, ● represents the concentration of organic substances adhering to the wafer surface when microwave irradiation was not performed in the above as a comparison. When the phthalate in the washing machine after the microwave irradiation was measured, 35 μg was obtained.
/ M was ^3, Incidentally, phthalic acid ester concentration in the cleaning device in the microwave unirradiated was 0.5～1Myug / m ^3. The analysis method is an adsorbent collection / GC / MS method.

[0046]

According to the present invention, the following effects can be obtained. 1) In cleaning the surface of the substrate, a high frequency was applied to the surface. (1) Adsorbed contaminants, for example, organic substances were desorbed from the substrate surface. (2) In the above, purification of a substrate surface capable of removing generated contaminants is provided by providing a generated contaminant removal unit using any one of an adsorbent, an ion exchange fiber, a photocatalyst, and a photoelectron in phosphorous contact with the high frequency action unit. It became a method. 2) According to the above (1) The removal method using adsorbents, ion exchange fibers, photocatalysts, and photoelectrons is the removal of contaminants in the space. Contaminants on the substrate were removed. That is, it became a cleaning space from which contaminants could be totally removed. (2) Due to these actions, the cleaning method of the present invention is suitable for pretreatment in a surface cleaning apparatus for silicon semiconductor substrates, glass substrates, metallic substance coated substrates, and analyzers in advanced industries such as semiconductor and liquid crystal manufacturing. Can be used.

[Brief description of the drawings]

FIG. 1 shows a basic configuration diagram of a cleaning device of the present invention, in which a microwave generator is installed in an upper part and in a side part.

FIG. 2 is a schematic configuration diagram showing an example of a cleaning device of the present invention.

FIG. 3 is a schematic configuration diagram showing another example of the cleaning device of the present invention.

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

FIG. 5 is a graph showing a relationship between a microwave irradiation time (minutes) and an organic substance concentration (ng / cm ² ) on a wafer surface.

FIG. 6 is a schematic view of the attachment of an organic substance to a wafer.

FIG. 7 is a schematic configuration diagram showing cleaning of air in a conventional clean room.

[Explanation of symbols]

1: Wafer purifier, 2: Wafer, 3: Organic substance, 4: Microwave generator, 5: Microwave, 6: UV lamp,
7: photocatalyst, 8-1, 8-2: air flow, 9: particulate matter,
10: Photoemission material, 11: Electrode, 12: Adsorbent, 1
3: dust filter, 14: fan, 15: filter, 1
6: Si filter, 17: moisture layer, 18: organic matter adhesion,
A: Wafer storage space (microwave irradiation part), B: Removal part, M: Magnetron

Claims (4)

[Claims] 1. A method of cleaning a contaminated substrate surface, wherein high-frequency energy is applied to the substrate surface, and contaminants generated from the substrate surface by the application are collected and removed. Cleaning method. 2. A method for collecting and removing contaminants generated from the surface of the substrate by using at least one of means for collecting and removing contaminants using an adsorbent, ion exchange fibers, a photocatalyst, or photoelectrons. 2. The method for cleaning a substrate surface according to claim 1, wherein: 3. An apparatus for cleaning a contaminated substrate surface, comprising: a storage section for the substrate; a high-frequency generation section for applying high-frequency energy to the substrate surface; and a contaminant generated and collected from the substrate surface. An apparatus for cleaning a substrate surface, comprising a generated contaminant removing unit for removing the generated contaminant. 4. The generated contaminant removing section collects and collects contaminants using an adsorbent, an ion exchange fiber, a photocatalyst, or a photoelectron.
4. The apparatus for cleaning a surface of a substrate according to claim 3, wherein the apparatus comprises at least one of a removing unit.