JP2001205101A - Photocatalyst, photoelectron emitting material and reactor using both - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photocatalyst or a photoelectron emitting material which is used for decomposing and removing harmful organic materials in the air and in water and is easy to be handled and excellent in reaction efficiency and to provide a reactor in which a clean atmosphere is effectively created by using the photocatalyst and the photoelectron emitting material. SOLUTION: The photocatalyst 9 is obtained by filling a porous anodically oxidized film formed on the surface of Al or an Al alloy with TiO2 having 1-100 nm particle size as a photocatalyst material. The photoelectron emitting material, which emits photoelectrons by irradiating it with ultraviolet rays, is obtained by disposing a photoelectron-emissive material having 1-100 nm particle size on a base material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocatalyst, and more particularly to a photocatalyst for decomposing and removing harmful organic substances in the air and water, and a reaction apparatus using the photocatalyst. In addition, the present invention relates to a photoelectron emitting material, and more particularly, to a photoelectron emitting material capable of emitting high-concentration photoelectrons for a long period of time, and a reactor for generating negative ions and the like using the emitting material.

[0002]

2. Description of the Related Art In recent years, the scale (size) of an environment varies from a global environment to a living environment for humans and an environment for processing wafers (substrates) in semiconductors, but pollutants (hazardous substances) in the environment are different. ) Is regarded as a problem, and the emergence of a method for effectively removing (controlling) the contaminants is expected.

[0003] For example, in the semiconductor industry, not only fine particles but also gaseous substances are considered to affect wafer processing as contaminants as the quality and precision of products are further increased. Therefore, removal of fine particles has conventionally been sufficient, but removal (control) of gaseous pollutants will be important in the future. That is, a conventional filter installed in a clean room can only remove fine particles, and cannot remove gaseous pollutants contained in air introduced from outside air. Therefore, there is a problem in the conventional method.

Here, the gaseous pollutant will be described. The gaseous pollutants include (1) acid gases such as NOx and SOx, (2) basic gases such as NH ₃ and amines,
(3) Hydrocarbon (HC) and the like. Of these, hydrocarbons (HC) are particularly important as gaseous pollutants in ordinary clean rooms. The reason is that hydrocarbons (HC) are adsorbed on the wafer substrate and the base material to be processed at a normal clean room concentration level and exert an adverse effect.

[0005] Hydrocarbons (H.
C.) is degassing (gas generation) from automobile exhaust gas and polymer products introduced into the clean room, or a polymer material (for example, a plastic material of a polymer product, a release material, (Eg, an antioxidant) ("Air Purification", Vol. 33, No. 1, pp. 16-21, 1995).

Further, since a part or the whole of the reactor is covered with a plastic plate or the like, an organic gas is generated from these plastics. Furthermore, recently, from the viewpoint of energy saving, air in a clean room is often circulated for use. However, the concentration of the organic gas in the clean room is gradually increased, which may contaminate the base material and the substrate. become.

[0007] These hydrocarbons (HC) have an adverse effect on the base material and the substrate even at a very low concentration of about the concentration contained in ordinary air. More specifically, when a semiconductor substrate (for example, a wafer substrate in a semiconductor manufacturing process) is contaminated with hydrocarbons (HC), the affinity (fit-in) between the substrate and a photoresist applied to the surface of the substrate decreases. . When the affinity decreases, the film thickness of the resist is affected, the adhesion between the substrate and the resist is affected, and the quality of the product and the yield are reduced.

As described above, in the future, a product with a higher degree of integration, that is, a product with finer and higher precision will be required as a higher quality product. It is necessary to remove (control) gaseous pollutants such as organic gas. ("Air Purification", Vol. 33, No. 1, pp. 16-21, 1995).

As a method for treating organic matter in water, that is, a method for removing dissolved organic matter in wastewater, a method using a microorganism, an activated carbon method, an ozone method, an electrolysis method, a chemical oxidation method, an electrodialysis method, etc. The law is generally known.
Of these, those that are actually industrialized include:
There are activated carbon method, ozone method and electrolysis method.

[0010] However, these processing methods have the following problems. Activated carbon method Treatment efficiency is relatively good, but regeneration of activated carbon is troublesome and costly. Ozone method The efficiency of decolorization, deodorization and decomposition is relatively good as an organic matter treatment, and there is also a bactericidal effect.However, ozone is expensive to produce, and unused ozone is released as waste ozone. Pollution countermeasures for leak waste ozone are required. Electrolysis method Although the efficiency of decolorization as an organic substance treatment is relatively good, a sufficient effect on the decomposition of organic substances cannot be obtained. Also, the cost is high.

For each of the above processing methods, the present inventors have:
A photocatalyst in which a photocatalyst material is supported on the surface of a light-transmitting linear article was developed, and toxic gas treatment and water treatment using the photocatalyst were proposed. Although this photocatalyst is advantageous depending on the application destination of the treatment, further improvement is necessary in practical use. In particular, an improvement in the reaction rate is required.

On the other hand, there have been many proposals and research papers by the present inventors regarding the cleaning of a space by photoelectrons generated by irradiating a photoelectron emitting material with ultraviolet rays. For example, regarding (1) space purification,
No. 859, No. 6-3494, No. 6-7490
No. 9, Japanese Patent Publication No. 6-74710, Japanese Patent Publication No. 8-2211, and (2) Japanese Patent Publication No.
-74908, JP-B-7-93098, and Patent No. 28
No. 77449, Japanese Patent No. 2877487, JP-A-9-2
No. 94919, (3) Research papers, (a) Proc
eedings of the8th. World Clean Air Congress. 19
89. Vol. 3. Hagur p735-740 (198
9), (b) Pollution, Vol. 24. No5. p63-71
(1989), (c) Aerosol Research, Vol. 7, No. 3
No. 245-247 (1992), (d) Aerosol Research, Vol. 8, No. 3, pp. 239-248 (199)
3), Vol. 8, No. 4, p. 315-324 (199
3).

The conventional photoelectron emitting material is one kind of bulk (lumped) material, or a material obtained by adding a photoelectron emitting substance in a thin film to the bulk material, for example, an ultraviolet ray transmitting substance. A photo-emissive substance such as Au is placed on a glass plate.
Was used in the form of a thin film. As another example,
There is a material in which a photoelectron emitting substance, for example, Au is added in the form of a thin film to plate-like Cu-Zn. In the case of such a photoelectron emitting material, there is room for improvement depending on the application field, the device, and the required performance.

The conventional method of purifying a space by photoelectron emission is as follows.
An example will be described with reference to FIG. 6 in which a space is cleaned in a semiconductor factory. FIG. 6 shows an air purifying apparatus (A) in a clean room of about 1,000 class. The air cleaning device (A) is, for example, a class 1,000 in a semiconductor factory.
It is installed at the point of use to remove fine particles (particulate matter) in the clean room No. 0. That is, fine particles and gaseous substances are present as contaminants in the clean room. The fine particles are removed by the apparatus, and the clean air is supplied as clean air to the semiconductor manufacturing apparatus and its surroundings, thereby creating a clean environment. I keep it.

The air purifier (A) mainly comprises an ultraviolet lamp 31, an ultraviolet irradiation window glass 32, a photoelectron emitting material 33 in which Au is added to a plate-like Cu-Zn in a thin film form, and an electrode 34 for setting an electric field. , And a charged fine particle collecting material 35. Air containing fine particles in clean room 3
6 If _-1 enters the air cleaning device A, particulates in the air 36 _-1 is charged by photoelectrons 37 to be emitted from the photoelectron emission material 33 that has received the ultraviolet irradiation, becomes charged particles, on the downstream charged particulate collection It is collected in timber 35, the clean air _{36 -2} at the outlet. By the way, as described above, when the photoelectron emitting material 33 is used for a long time, the photoelectron emitting material 33 is contaminated by pollutants in the clean room air,
This leads to performance degradation (for example, easily adsorbed substances such as hydrocarbons are adsorbed on the surface). This is because in semiconductor factories, the concentration of hydrocarbons (HC) as gaseous pollutants in clean room air is higher than the concentration of outside air, causing pollution.

That is, recently, hydrocarbons (HC) generated from various solvents used in degassing from the polymer resins of the clean room constituent materials and work in the clean room have become a problem as a hydrocarbon generation source. As a cause of hydrocarbons (HC), hydrocarbons introduced from the outside air in a normal clean room (the hydrocarbons in the outside air are introduced into the clean room because the filters in the clean room cannot remove hydrocarbons) Since the hydrocarbons generated in the clean room are added as described above, the hydrocarbons in the clean room have a higher concentration than the outside air. Moreover,
Since the circulating use of clean room air is increased in terms of energy saving, the hydrocarbon concentration in the clean room is concentrated, and depending on the clean room, the concentration is considerably high. In addition, the demand for local cleaning has been increasing from the viewpoint of an energy-saving clean room, and in this case, the use ratio of the polymer resin to the air volume increases, so that the hydrocarbon concentration increases [( a) Air Purification, Vol. 32, No. 3, pp. 43-52 (1994),
(B) Ultra Clean Technology, Volume 7, 4
No., pp. 15-20 (1995), (c) Clean Technology, 12. p45-50 (1995), (d) Japan Federation of Industrial Machinery Industries, 1994, research on energy saving and cost reduction, optimal clean room structure, p41
To 49 (1995)].

The degree of such contamination can be represented by the contact angle of the surface of the substrate or the substrate. If the contamination is severe, the contact angle is large. A substrate or substrate having a large contact angle, even when formed on the surface thereof, has a low adhesion strength of the film (poor adaptability) and causes a decrease in yield. 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 is attached to the surface of the substrate, 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. That is, in the manufacturing process for handling wafers, it has become necessary to remove gaseous contaminants in addition to removing fine particles.

In response to this requirement, the present inventors have developed a photoelectron emitting material in which at least a substance that emits photoelectrons by ultraviolet irradiation and a substance that exhibits a photocatalytic action by ultraviolet irradiation are arranged on the same surface. (Japanese Patent Application Laid-Open No. 9-294919). These materials are effective depending on the place of use and conditions of use, but it is necessary to develop a more practically effective photoelectron emitting material.

[0019]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and provides a photocatalyst which is easy to handle and has a high reaction efficiency, and a method for effectively removing harmful substances using the photocatalyst. It is an object to provide a reactor for processing. It is another object of the present invention to provide a photoelectron emitting material capable of stably and efficiently emitting high-concentration photoelectrons for a longer time.

[0020]

In order to solve the above-mentioned problems in the prior art, the present invention according to the first aspect of the present invention provides a photocatalyst having a porous anodic oxide film formed on the surface of Al or an Al alloy. TiO with particle size of 1-100nm as material
₂ is a photocatalyst characterized by being filled with ₂ . In this case, the porous anodic oxide film preferably has pores of 10 to 500 nm.

According to a second aspect of the present invention, there is provided a photoelectron emitting material which emits photoelectrons by irradiating ultraviolet rays, wherein the emitting material has a photoelectron emitting material having a particle diameter of 1 to 100 nm on a base material. It is characterized by being deployed. Here, the base material of the photoelectron emitting material is preferably a TiO ₂ material.

According to a fourth aspect of the present invention, a photocatalyst according to the first aspect is used as a photocatalyst, and / or a photoelectron emitting material according to the second aspect is used as a photoelectron emitting material.
Further, a light irradiation means for irradiating the photocatalyst and / or the photoelectron emitting material with light is provided. Here, it is preferable that the light irradiation means includes a light source of ultraviolet light having a wavelength of at least 254 nm.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Photocatalyst] First, the present invention relating to a photocatalyst has been made based on the following three findings. (1) The photocatalyst can decompose and remove harmful organic substances. However, as described above, the conventional photocatalyst has a low reaction rate (decomposition rate / removal rate) and has a practical limit. (2) For the above (1), a porous anodic oxide film is formed on the surface of Al or an Al compound,
By filling the fine pores with a photocatalyst material of TiO2 of ₁ to 100 nm, a photocatalyst with an improved reaction rate can be obtained. (3) A more effective result can be obtained by using a germicidal lamp (main wavelength: 254 nm) as an irradiation source of ultraviolet rays to the photocatalyst.

Hereinafter, the photocatalyst according to the present invention and a reaction apparatus using the photocatalyst will be described in detail.

The photocatalyst of the present invention is a photocatalyst in which pores of a porous anodic oxide film formed on the surface of Al or an Al alloy as a base material (base material) are filled with a photocatalytic material. Has a pore size of 10 to 500 nm, preferably 50 to 200 nm, and has a center diameter of 1 on the inner surface of the pore.
It is characterized in that it is coated with a photocatalyst material of about 100 nm.
The shape of the Al or Al alloy can be an appropriate shape such as a plate shape, a honeycomb shape, a pleated shape, a granular shape, a fibrous shape, a net shape, a linear shape, and a spherical shape. Further, the photocatalyst of the present invention can be used by being present in the wall surface or space of the device.

Hereinafter, a method for producing the photocatalyst will be described.
First, Al or Al alloy is anodized, thereby
A porous anodic oxide film having pores having a size of 10 to 500 nm is formed on the surface of the l or Al alloy. Next, a photocatalytic material, for example, T
iO ₂ is filled into the pores.

The size of the pores of the porous anodic oxide film is _two times the (average) particle size of the photocatalyst material (for example, TiO ₂ ).
It is good to double, preferably five times, more preferably ten times. For example, when the particle size of the photocatalyst material is 5 nm, it is difficult to fill the photocatalyst material if the pore size of the film is smaller than 10 nm. On the other hand, when the size of the pores is 500 n
When it is larger than m, the adhesive force in fixing the photocatalyst material becomes insufficient (desorption of TiO ₂ occurs). In the case of TiO _{2 having} a particle size of 5 nm, an appropriate pore size is 5
0 nm.

As described above, the size of the pores can be appropriately selected based on the average particle size of the photocatalyst material. Generally, the pores of the porous anodic oxide film have a size of 10 to 500 nm. The anodic oxide film having pores of this size can be appropriately formed by changing the conditions for forming the anodic oxide film, that is, changing the anodic oxidation conditions. Usually, when the thickness of the anodized film is 1 to 200 μm, 1
Fine pores having a size of 0 to 500 nm are effectively formed.

Next, the above-described method for producing a photocatalyst is described in the following.
This will be described more specifically by taking, as an example, a case where plate-like Al is used as the substrate.

As described above, it is necessary to first perform anodic oxidation. Prior to this anodic oxidation, 30% nitric acid and 5 g /
The Al substrate is pre-treated with an aqueous solution of sodium hydroxide, and then dried.

The obtained substrate was treated with 85% phosphoric acid at 30 g / l-
Al anodic oxidation by immersing in a 30 g / l maleic acid mixed solution and applying a direct current of 1 A / dm ^{2 to} the carbon cathode for 50 minutes while maintaining the bath temperature at 30 ° C. I do. As a result, a thickness of 40
A μm anodic oxide film (pore diameter is 50 nm) is formed.

Next, ultrafine TiO ₂ particles are dispersed and fixed on the Al anodic oxide film by electrophoresis. That is, TiO ₂ ultrafine particles having a particle size of 1 to 100 nm are dispersed in distilled water as a dispersion for electrophoresis.

First, an anodized Al substrate (cathode) and a carbon electrode (anode) are immersed in a TiO ₂ ultrafine particle dispersion, left for 1 minute, and then kept at a bath temperature of 30 ° C. for 75 minutes.
By applying a constant voltage of V for 10 minutes, the TiO ₂ ultrafine particles are electrophoresed in the cathode direction. The Al substrate subjected to the electrophoresis treatment was washed with water and dried, and then dried at 200 ° C.
For 30 minutes. Thereby, the TiO ₂ ultrafine particles are fixed in the Al anodized film.

The Al alloy which can be used in the present invention is not particularly limited as long as it can form a porous anodic oxide film having pores of 10 to 500 nm on its surface by anodic oxidation. May be. For example, Al
-Cu-based alloy, Al-Mn-based alloy, Al-Si-based alloy,
Al-Mg based alloy, Al-Mg-Si based alloy, Al-Z
An n-based alloy can be used.

Here, the light used in the production of the photocatalyst is
The catalyst material is TiO of 1 to 100 nm. ₂Ultra fine particles,
Such fine TiO₂Is a feature of the present invention.
It is. It should be noted that TiO having a particle size as described above₂That
Anything can be used as a photocatalyst material
be able to.

The photocatalyst material used for the photocatalyst (TiO)
An example of the manufacturing method ₂ ) will be described below. (1) A solution of the following raw material (alcoholate) is dissolved in alcohol, and water is added thereto. Raw materials: titanium tetraisopropoxide, titanium (IV) tetra n-butoxide, titanium tetranormal butoxide (2) Next, the solution of (1) is sprayed and heated (600 to 90
0 ° C.) (spray pyrolysis method)
_Two particles are obtained. Since the particle size of the obtained TiO ₂ varies depending on the heating temperature, an appropriate heating temperature may be selected in consideration of the size of the pores on the Al surface and the like.

Next, a light source as light irradiation means for irradiating the photocatalyst with light will be described. The light source may be any light source having a wavelength that excites the photocatalyst, and a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, a xenon lamp, or the like can be used. In addition, depending on the place where the optical medium is used, sunlight can also be used.

The position of the light source depends on the field of application of the photocatalyst,
It can be appropriately selected according to the type of light source and the shape of the device. Usually, when a light source is installed inside the reactor, all the light emitted radially from the light source is effectively used, so it is preferable to install the light source inside the reactor.

Examples of such a light source include a germicidal lamp, a black light, a fluorescent chemical lamp, a UV-B ultraviolet lamp, and a xenon lamp. For air cleaning, a germicidal lamp (main wavelength: 254 mm) is preferable. .
This is because the germicidal lamp is inexpensive and ozone-free, can increase the amount of irradiation light per area of the photocatalyst, and can improve processing efficiency.

In the water cleaning treatment, 200 n
A low-pressure mercury lamp including both a wavelength of less than m and a wavelength of 254 nm is preferred. Ozone is generated by ultraviolet rays having a wavelength of 200 nm or less, and this ozone is also involved in the cleaning treatment. Also, with respect to the photocatalyst, the irradiation light amount per area of the photocatalyst can be increased by short-wavelength ultraviolet rays, and the processing efficiency can be improved. Therefore, the processing efficiency is improved by the action of both the ozone and the photocatalyst.

It should be noted that the photocatalyst can be appropriately combined with a known harmful substance removing means depending on the place, state, and the like. Well-known harmful substance removing means include activated carbon, activated carbon fiber, zeolite, ion exchange filter (fiber), organic polymer filter (organic polymer bead) and the like.

For example, an ionic substance (eg, N
When a large amount of H ₃ , amine, NOx, SOx) is contained, the ionic substance is previously collected and removed by a method using the above-mentioned activated carbon or ion-exchange fiber, thereby improving the processing efficiency of the photocatalyst. It is preferable because it can be used. In particular, ion-exchange fibers are more preferable because they have low pressure loss and are effective (high collection efficiency). The ionic substance and the organic substance can be removed at the same time by the ion exchange fiber and the photocatalyst of the present invention.

Hereinafter, embodiments of the present invention will be specifically described. Note that the present invention is not limited to these examples.

Embodiment 1 FIG. 1 is a schematic configuration diagram of an air cleaning system using a reaction apparatus of the present invention, and shows an air cleaning system for removing trace harmful gases in a clean room 1 in a semiconductor factory. .

In FIG. 1, class 1000 (ie, class 1000)
In a clean room 1 in which the number of particles of 0.1 μm or more is 1000 in 1 ft ³ ), NOx, NH ₃ , hydrocarbons (HC) and fine particles 3 are generated as harmful gaseous pollutants by the processing apparatus 2. . The air in this clean room 1 contains hydrocarbons (non-methane hydrocarbons, HC) of 1.2 to 1.2
Present at a concentration of 1.5 ppm.

These harmful gases (these gaseous contaminants and fine particles) contaminate the raw materials (wafers) of semiconductor factories, their products, and semi-finished products. Is installed to collect and remove the gaseous pollutants and fine particles.

[0047] The air cleaning device A is mainly preprocessing filter 5, a fan 6, an ion-exchange filter (cationic and anionic) 7, ULPA filters _{28-1, 8-2,} photocatalyst 9 and the ultraviolet lamp of the present invention 10.

The air to be treated 11 containing harmful gas is supplied to the fan 6
Is sucked into the air purifier A, and the clean air processed by the air purifier A is discharged in the direction of the arrow. Then, the clean air 12 is supplied to the semiconductor manufacturing apparatus 13.

The pretreatment filter 5 is a filter mainly composed of glass fiber having a low air resistance. The pretreatment filter 5 causes coarse particles (particles having a relatively large particle diameter) in the air to be treated 11 sucked. Is removed.

The photocatalyst 9 is composed of a porous anodic oxide film (average pore size of 50 nm) obtained by anodizing honeycomb-shaped Al and a TiO ₂ (photocatalytic material) having a particle size of 5 nm.
Is filled by electrophoresis.

When harmful gas is generated in the clean room 1, it adheres to products and semi-finished products, causing an increase in the contact angle.
Further, the yield is reduced, and the productivity is reduced. Therefore, reducing the concentration of this harmful gas to a certain level or less is important for clean room management. here,
The contact angle is an index indicating the degree of contamination on a solid (wafer) surface. The contact angle of water on a solid surface reflects the state of contamination well, with a large degree of contamination having a large contact angle and a small degree of contamination having a small contact angle.

The order of combination of the photocatalyst and the well-known harmful substance removing means is not limited to the present embodiment, but can be appropriately selected based on the results of preliminary tests and the like.

(Embodiment 2) FIG. 2 shows a clean room 1 of a class 1000 semiconductor factory according to the first embodiment.
A stocker (storage) for preventing an increase in the contact angle of a wafer installed in a local clean zone of class 10 in FIG.
4 is a schematic configuration diagram of FIG. In the figure, A is a contaminant removing section comprising the photocatalyst 9 and the germicidal lamp 10 of the present invention, B is a wafer storage section of the stocker 4, and 16 is a wafer storage case.

The air in the clean room contains hydrocarbons.
(HC) is present at a concentration of 1.4 to 1.6 ppm. The hydrocarbon is derived from air introduced from outside air and from degassing from clean room components. Incidentally, the hydrocarbon concentration outside the clean room (outside air) is 0.8 to 1.2 ppm, which is lower than that in the clean room. This is because hydrocarbons are generated from clean room components and the like in the clean room (Ultra Clean Technology, Vol. 7, No. 4, pp. 15-20,
1995).

These hydrocarbons adhere to the wafer substrate surface and reduce the yield. The degree of contamination by the hydrocarbons can be represented by the contact angle (Air Purification, Vol. 33, No. 1, p. 16-21, 1995).

The stocker 4 is a device for preventing contamination of the wafer 14 (preventing an increase in the contact angle).
An ultraviolet lamp (germicidal lamp) 10 and a light shielding material 15 for avoiding direct irradiation of ultraviolet rays to products such as wafers 14 and semi-finished products.

The photocatalyst 9 was prepared by electrophoresis of TiO ₂ having a particle size of 10 nm as a photocatalyst on a porous anodic oxide film (average pore size: 100 nm) obtained by anodizing plate-like Al. It is filled.

A slight temperature difference between the upper and lower portions of the photocatalyst 9 caused by the irradiation of the ultraviolet lamp 10 generates an air flow in the stocker 4 and flows in the directions of arrows 11 and 12.

The air containing the harmful gas such as hydrocarbons and NH ₃ in the stocker 4 is sequentially carried to the removing section A in which the photocatalyst 9 is installed by the above airflow, and is effectively treated. Accordingly, the stocker 4 has an NH ₃ concentration of 1 ppb or less,
The hydrocarbon concentration becomes 0.1 ppm or less, and the air in the stocker 1 becomes ultra-clean air that does not increase the contact angle of the wafer 14.

(Embodiment 3) FIG. 3 is a schematic configuration diagram of a water treatment apparatus 20 using a photocatalyst of the present invention. In FIG. 3, biochemically treated raw water for drinking water is introduced into a removal section A through a raw water inlet 21. At the removal section A, trace organic substances, particularly organic chlorine compounds, in the raw water are oxidatively decomposed and treated. Water is discharged from outlet 22.

The water treatment apparatus 20 includes a removing section A mainly composed of the photocatalyst 9 and the ultraviolet lamp 10, a blower 18 for sending air bubbles 17 for promoting a reaction in the removing section A, and a diffuser 19. And an air supply unit C having

The photocatalyst 9 is prepared by subjecting a porous anodic oxide film (average pore size: 30 nm) obtained by anodizing a spherical Al material to TiO ₂ having a particle size of 3 nm as a photocatalyst by electrophoresis. It is filled with.

The air is diffused by the blower 18 through the air diffuser 19.
Is supplied to the raw water through the air, and the air rises as bubbles in the removing section A. Then, the removing portion A is formed by the stirring action or the like.
Is promoted.

In the removing section A, organic matter in raw water, especially organic chlorine compounds (eg, trichloroethylene, tetrachloroethylene) is effectively removed by the photocatalysis by the photocatalyst 9 of the present invention irradiated with an ultraviolet lamp (low-pressure mercury lamp) 10. Decomposes into safe water.

It should be noted that the field of application of the above device, the type of light source,
Depending on the scale, type, and shape of the device, the light source 10 may be provided outside the water treatment device 20 and the internal photocatalyst 9 may be irradiated with ultraviolet rays from the external light source.

Example 4 Sample air from a semiconductor factory shown below was put into the stocker 4 shown in FIG. 2, and the photocatalyst of the present invention was irradiated with ultraviolet rays to determine the contact angle on the wafer stored in the stocker 4. It was measured. In addition, a Cr film was formed on the wafer, and the adaptability (adhesion) of the film to the wafer was also measured. Further, the hydrocarbons adsorbed on the wafers in the stocker 4 were identified, and the concentration of non-methane hydrocarbons in the stocker was examined. It should be noted that, for comparison, a case where no photocatalyst material was used was similarly examined.

Stocker size: 100 liters, light source: 10 W sterilizing lamp (wavelength: 254 nm), photocatalyst: plate-like Al was anodized, and a porous anodic oxide film (pore size: 3)
(0-80 nm, average 50 nm), and filled with fine particles of TiO ₂ having an average particle diameter of 5 nm by electrophoresis. The installation area of the photocatalyst was 600 cm ² . Contact angle measurement; water droplet contact angle method [Kyowa Interface Science Co., Ltd.
CA-DT type], film formation on wafer; Cr thickness of 300 nm, sputtering method, adhesion of formed Cr; scratch test (RHESCA
Measurement of non-methane hydrocarbons in stockers; Gas chromatograph (GC); Identification of hydrocarbons adsorbed on wafers; GC / MS method; Sample gas; Class 100 clean room air in a semiconductor factory; 5 inches wafer 1cm × 8cm; 80ppb, wafers in the stocker: HC concentration: 1.2~1.5ppm (non-methane hydrocarbons), NH ₃ concentration
Cut, after the following pre-treatment, placed in the depot, pretreatment of the wafer; after washing with detergent and alcohol, ultraviolet irradiation at O ₃ occurred under (UV / O ₃ cleaning).

The photocatalyst was produced by the following treatment using plate-like Al. (1) Pretreatment 30% nitric acid and 5 g / l sodium hydroxide aqueous solution
After pretreatment of the substrate, it was dried. (2) Formation of an anodic oxide film 85% phosphoric acid 30 g / l-maleic acid 3
0 g / l system mixed solution, and while maintaining the bath temperature at 30 ° C., a current density of 1 A / dm ² between it and the carbon cathode.
Anodization was performed by applying a direct current of 50 minutes for 50 minutes. As a result, an anodized film having a thickness of 10 μm was formed on the Al surface (measurement was performed by scanning electron microscope analysis). In addition, pores having a center diameter of 50 nm were obtained in this film (measured by a cross-sectional SEM photograph).

(3) Production of TiO ₂ Titanium tetraisopropoxide was dissolved in alcohol, and water was added thereto to form a solution. Next, spray heating (8
00 ° C.). Thereby, Ti having an average particle size of 5 nm
O ₂ was obtained (TiO ₂ collected on a glass plate was SE
M photo). (4) Filling (introducing) TiO ₂ into the film of (2) Using distilled water as a dispersion for electrophoresis,
The O ₂ was dispersed.

Next, the anodized Al substrate (cathode) and the carbon electrode (anode) were immersed in a TiO ₂ ultrafine particle dispersion, left for 1 minute, and kept at 30 ° C. while maintaining the bath temperature at 30 ° C.
By applying a constant voltage of 5 V for 10 minutes, TiO ₂
The fine particles were electrophoresed in the direction of the cathode. The Al substrate subjected to the electrophoresis treatment was washed with water, dried, and then heat-treated at 300 ° C. for 30 minutes. Thereby, the TiO ₂ ultrafine particles were filled in the Al anodized film. The immobilization by the introduction of TiO ₂ into the coating is performed by the composition analysis in the depth direction by the EPMA method.
It was confirmed that the iO ₂ fine particles were dispersed and fixed in the anodized film.

(Experimental Results in Example 4) FIG. 4 is a graph showing changes in the contact angle (angle) and the adhesive force (mN) according to the elapsed time. In FIG. 4, the contact angle when there is a photocatalyst is indicated by -O-, and the contact angle when there is no photocatalyst is indicated by-●-. In addition,-力-indicates the adhesive force with the photocatalyst, and-▲-indicates the adhesive force without the photocatalyst.

As described above, when the photocatalyst was present, neither the contact angle nor the adhesive force changed over time.
In the absence of the photocatalyst, the wafer was taken out after 40 hours and 140 hours, and the hydrocarbon adhering to the wafer was desorbed by heating, and the phthalate was detected by GC / MS. On the other hand, when a photocatalyst was present, it was not detected.

The concentration of the non-methane hydrocarbon in the stocker may be controlled for 1 hour, 30 hours, 100 hours when a photocatalyst is present.
After the elapse of 200 hours, the concentration was 0.1 ppm or less.
After 5 hours, 100 hours, and 200 hours, the content was 1.2 to 1.4 ppm in all cases. In addition, N in stocker 4
The measured H ₃ concentration was 1 ppm or less.

Comparative Example The removal rate of hydrocarbons (HC) was compared with the experimental results in Example 4 by using a conventional photocatalyst by the sol-gel method.

As a conventional photocatalyst, an Al plate coated with TiO ₂ by a sol-gel method (JP-A-9-20504)
No. 6) was used. The installation area of the photocatalyst is 600 cm ² . The test was performed using the same stocker and sample air (H.
C. Average concentration: 1.3 ppm), and the hydrocarbon concentration in the stocker 4 was examined.

FIG. 5 shows the results of this experiment. In FIG. 5, the case where the photocatalyst of the present invention is used is indicated by-○-, and the case where the conventional photocatalyst is used is indicated by-●-. In FIG. 5,
The arrow indicates the detection limit (0.01 ppm or less).
As shown in the figure, when the photocatalyst of the present invention was used, it was found that the hydrocarbon (HC) concentration was rapidly reduced.

[Photo-Emitting Material] Next, an embodiment of the photo-emitting material of the present invention will be described. The present invention relating to a photoelectron emitting material has been made based on the following four findings. (1) Regarding generation of photoelectrons from a photoelectron emitting material, there are several inventions of the present inventors so far (Japanese Patent Publication No.
No. 74909, Japanese Patent Publication No. 7-93098, Patent No. 287
No. 7449, Japanese Patent No. 2877487, JP-A-9-29
No. 4919). What is common to these photo-emissive materials is that an appropriate base material is coated with a photo-emissive substance (eg, Au) in the form of a thin film, or the photo-emissive substance is formed into particles (islands). It is added. In contrast,
When a photoelectron-emitting substance having a particle diameter (average) of 1 to 100 nm is added to the base material, the photoelectron emission becomes extremely effective.

(2) When the photoelectron emitting material is used in an environment (eg, a clean room) containing a large amount of organic substances (for example, hydrocarbons), the photoelectron emitting material is affected by the environment over a long period of use, and its performance is reduced. This is because organic substances (such as hydrocarbons) in the environment in which the photoelectron emitting material is used adhere to the surface and are caused. (3) Since the organic substance is decomposed and removed by a photocatalyst irradiated with ultraviolet light, in an application containing a high concentration of hydrocarbon,
It is important to dispose the photoemission material and the photocatalyst on the same surface for long-term stable use. That is, in such an application, it is effective to add a photoelectron emitting substance having a particle diameter (average) of 1 to 100 nm on TiO ₂ as a base material, for example. (4) Photoelectrons generated from the photoelectron emission material adhere to surrounding electrophilic substances, for example, O ₂ and H ₂ O, and generate negative ions (Aerosol Research, Vol. 8, No. 3, p. 239)
248, 1993).

It should be noted that negative ions are generated from the emitted photoelectrons.
Show the reaction equation (Aerosol Research, Vol. 8, No. 3, p2
39-248, 1993). O₂+ E → O₂ ⁻  O₂ ⁻+ H₂O → O₂ ⁻(H₂O) O₂ ⁻(H₂O)_n-1+ H₂O → O₂ ⁻(H₂O)_n

Next, an embodiment of the present invention will be described.

First, a substance that emits photoelectrons upon irradiation with ultraviolet rays (photoelectron emitting substance) will be described. The substance can be additionally disposed on a base material (base material) described later, and emits photoelectrons by ultraviolet irradiation.

The photoelectron emitting material of the present invention can be prepared by adding 1 to 1
00 nm, preferably 1 to 30 nm, more preferably 1 nm
It is characterized in that a photoelectron emitting substance having a particle size (average) of about 10 to 10 nm is added.

For this purpose, according to the present invention, ultrafine particles having the above-mentioned particle diameter, whose central part is substantially made of a metal component and whose periphery is surrounded by a metal organic compound, are first added to the base material, and then heated. As a result, organic matter is decomposed / removed, and a photoelectron emitting material composed of a metal component is deposited on the base material. That is, when decomposing and removing the organic matter,
The photoelectron-emitting substance on the base material is firmly fixed by sintering to the base material. The metal organic compound is a photo-emissive substance (for example, Japanese Patent Publication No. 6-74908, Japanese Patent Publication No. 7-930).
98, and JP-A-9-294919).

The photo-emissive substance of the present invention comprises a component derived from a metal organic compound, for example, Cu, Ag, A
u, Zn, Cd, Ga, In, Si, Ge, Sn, P
d, Fe, Co, Ni, Ru, Rh, Pd, Os, I
r, Pt, V, Cr, Mn, Y, Zr, Nb, Mo, C
a, Sr, Ba, Sb and Bi.

In the present invention, gold which can be used as a raw material
The organic compounds of the genus include organometallic compounds and metal alkoxides.
Sid and the like are also included. Particularly limited as metal organic compounds
However, any commercially available product can be used. For example,
Phthenate, octylate, stearate, benzoic acid
Salts, fatty acid salts such as paratoluate and n-decanoate,
Metal alkoxides such as isopropoxide and ethoxide,
An acetylacetone complex salt of the above-mentioned metals is exemplified. this
Among them, oleate, paratoluate,
Thearate, n-decanoate, metal ethoxide, metal
Acetyl acetonate and the like are preferred. As a fatty acid salt
Is particularly preferably a straight-chain fatty acid, and usually has 6 to 30 carbon atoms.
Degree, more preferably 10-18. These substances
The production of ultrafine particles, which is the main point of the present invention, from (raw materials)
In an inert gas atmosphere in which
Above the decomposition start temperature of organic compounds and below the complete decomposition temperature
Can be obtained by heating at a temperature of here
And the inert gas is N₂, CO ₂, Ar, He
In each case, one kind of gas can be used.

The above-mentioned heating temperature can be appropriately set according to the kind of the metal organic compound and the like. For example, in the case of a metal organic compound having a decomposition start temperature of about 200 ° C. and a complete decomposition temperature of about 400 ° C., the heating temperature may be maintained within a temperature range of 200 ° C. to 400 ° C. The holding time can be appropriately changed according to the heating temperature and the like. The ultrafine metal particles may be produced by heating a metal salt at a temperature lower than its decomposition reduction temperature and lower than its decomposition temperature in the presence of an ionic organic substance.

Next, a base material on which the above-mentioned photoelectron emitting substance is deposited will be described. Mother material, the light emissive material as long as it can be deposited, for example, as a metal, Al, Cu-Zn, stainless steel, glass, ceramics, and TiO ₂ as the optical medium as a non-metal. T
iO ₂ has, on appropriate the base material, the TiO ₂ sol - gel method, a method by coating, vapor deposition, sintering method, 600 to 1200 ° C. sputtering, the by addition or Ti material in an oxygen-containing atmosphere By sintering at the following temperature. Further, the photocatalyst of the present invention, namely, Al or Al
The particle size of the porous anodic oxide film formed on the surface is 1 to 10
A material filled with 0 nm of TiO ₂ can also be suitably used.
In the photocatalyst of the present invention, in particular, T
By using iO ₂ ultrafine particles, it is possible to function as a photocatalyst having a rapid purification ability as described above.

Further, depending on the application, direct addition to an ultraviolet lamp described later can be performed (Japanese Patent Laid-Open No. 4-24).
No. 3540). The surface of the lamp of the photoemissive substance is
Since they are integrated, the device can be downsized (compacted) and is preferable depending on the application destination (use).

The shape of the base material may be plate, pleated, linear,
An appropriate shape can be used depending on the application, the type and scale of the device, such as a net shape and a cylindrical shape.

When the photoelectron emitting material is irradiated with ultraviolet rays in an electric field, photoelectrons are effectively generated from the photoelectron emitting material. The method of forming the electric field can be appropriately selected depending on the shape, structure, application field, expected effect (accuracy), and the like of the negative ion generating portion. The strength of the electric field can be appropriately determined depending on the type of the photoelectron-emitting substance and the like.

The electric field strength is generally from 0.1 V / cm to 2 V / cm.
kV / cm. The electrode material and its structure may be those used in ordinary charging devices. For example, as the electrode material, linear, mesh, plate-like tungsten, SUS material,
Cu-Zn alloy is used.

In the formation of the electric field, in order to form a uniform electric field, it is preferable to first apply a conductive substance on the base material when applying the photoemission material on the base material.

Conductive substances on the base material (eg, In ₂ O ₂ ,
Alternatively, the deposition of a SnO ₂ -based conductive film) has another invention of the present inventors (see Japanese Patent No. 2598730), and can be used as appropriate.

The conductive substance adheres more firmly to the fine photoelectron emitting substance than the usual base material (eg, Al, SUS, Cu—Zn). Therefore, as described above, the addition of the conductive substance onto the base material is also preferable in this point (strong attachment of the photoelectron-emitting substance) depending on the use destination (use).

Next, an ultraviolet irradiation source will be described. The irradiation source emits photoelectrons from the substance that emits photoelectrons by irradiating the above-described photoelectron emitting material, and those using a photocatalyst as the base material may be those that simultaneously exert a photocatalysis. Generally, a mercury lamp, a hydrogen discharge tube, a xenon discharge tube, a Lyman discharge tube and 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. Among them, a germicidal lamp (main wavelength: 254 nm) is preferable.
This is because the germicidal lamp is ozone-less, has a large irradiation light amount per irradiation area, and has a germicidal (sterilizing) action.

The photoelectron emission performance is improved by depositing a photoelectron emitting substance having a particle size of 1 to 100 nm on the base material. The details of this reason are unknown, but in our studies,
It is considered that the ultra-fine photoelectron-emitting substance on the surface of the base material is uniformly arranged, resulting in (1) a decrease in surface energy and (2) an increase in the interface between the base material and the photoelectron-emitting substance.

The reason why the above-mentioned photo-emissive substance is uniformly arranged is that the photo-emissive substance used in the photo-emissive material of the present invention has a structure in which a metal organic compound is surrounded around a metal core. Therefore, when applied on the base material,
This is because it is considered that the metal core, that is, the photo-emissive substance is uniformly dispersed on the base material.

Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

(Embodiment 5) FIG. 7 shows a structure of a refresh room having a negative ion generator A in which the negative ion generator A is used for a comfortable space (amenity). FIG.
The negative ion 37 mainly comprises a photoelectron emission material 33, an ultraviolet lamp 31, an electric field setting electrode 34 for emitting photoelectrons from the photoelectron emission material 33, an air supply fan 39, and a dust filter 40. Generated at A.

The air 36 _-1 in the refresh room is
The air blower 39, firstly dedusted by dedusting filter 40, the clean air 36 _-3 particles have been removed.

The photoelectron emitting material 33 of the present invention is irradiated with ultraviolet rays by ultraviolet rays radiated directly from the ultraviolet lamp 31, whereby photoelectrons are emitted on the surface of the photoelectron emitting material 33.

The photoelectrons are subjected to the action of the electric field by the electrodes, and move toward the electrode 34, where the air
_-3 under the action of moisture and oxygen, and changes to negative ions 37. Note that the ultraviolet lamp 31 of the present example is a sterilizing lamp.

[0103] negative ions under the action of the flow of air 36 _-3 flowing, negative ions enriched air negative ion generator A
From the outlet _36-2 . Reference numeral 41 denotes a person, and the person 41 becomes comfortable (exhilaration) by the negative ion-enriched air, and the working efficiency is improved (refreshed). Reference numeral 42 denotes a chair.

Here, air 36 for generating negative ions is used.
_-1 is a filter for dust removal as in this example and / or a charging / collecting method using photoelectrons proposed by the present inventors (eg, Japanese Patent Publication No. 3-5857, Japanese Patent Publication No. 6-74909).
No., Tokiko 6-74910, Tokiko 7-110342
Dust is removed according to each publication. This is because the use of clean air 36 _-3 which is dust, photoelectrons emitted from the photoelectron emission material 33 is for Effective negative ions. The concentration of the released negative ions in this example is 5 × 10 ⁴ /
m1 to 6 × 10 ⁴ cells / ml.

Here, the photoelectron emitting material 33 is a feature of the present invention, and the manufacturing procedure will be described below. (1) Production of ultrafine Au as a photoemission material

In this embodiment, gold stearate is used as the metal organic compound.

First, 100 g of gold stearate was weighed,
This is charged into a 500 ml eggplant type flask and heated under a nitrogen stream (flow rate 100 ml / min.). The heating temperature is set to 250 ° C., and this temperature is maintained for 4 hours. With heating, the gold stearate is first melted, then thermally decomposed and denatured, and the obtained sample is purified by solvent extraction to obtain a powder. Observation of the powder with a transmission electron microscope revealed that the powder was composed of ultrafine particles having a particle size of about 3 nm. Furthermore, when powder X-ray diffraction was performed, a metallic gold core was confirmed. Further, when the ratio of the metal component was determined by thermal analysis, it was confirmed that the organic group occupied about 25% by weight, and from the results of elemental analysis and the like, it was a stearic acid group.

(2) Attaching to a base material having a particle diameter of 3 nm Au When the powder produced in the step (1) is dispersed in n-hexane, no precipitate is observed and a transparent state is obtained. Next, the ultrafine particles (Au) in a soluble state are applied to an Al material as a base material, dried, and heated at 250 ° C. for 2 hours to obtain Au.
The ultrafine particles fuse with each other and the organic substances dissipate. As a result, a photoelectron emission material in which Au (ultrafine particles) as a photoelectron emission substance is uniformly applied (coated) on the Al surface of the base material is obtained.

(Embodiment 6) This is a modification of the photoelectron emission material 33 of Embodiment 5 shown in FIG. Photoemission material 33 of this example
Is obtained by adding a photoelectron emitting substance to a photocatalyst (base material). Since the photoelectron emission material 33 exerts a photocatalytic action upon irradiation with ultraviolet light, contaminants attached to the material, for example, hydrocarbons are decomposed and removed by the photocatalyst, and stable performance is maintained for a long time. The outlet air 36 shown in FIG.
_-2 is clean air from which gaseous harmful components such as hydrocarbons have been removed. Here, Al or A is used as a photocatalyst.
1-10 particle size on the porous anodic oxide coating formed on
It is more preferable to use one filled with 0 nm of TiO ₂ . Thereby, a strong photocatalysis can be obtained.

The procedure for producing the photoelectron emitting material is as follows. (1) Production of ultrafine particles Au as a photoelectron emitting substance
Using gold stearate as metal organic compound
And the same as in the fifth embodiment. (2) Base material (TiO)₂) Production of Ti (base material) in an oxygen-containing atmosphere at 900 ° C for 30 minutes
To achieve. As a result, about 10 μm of TiO
₂A film is formed, resulting in a material that acts as an optical medium
You. The above-mentioned porous anodic oxide film of aluminum₂
It may be filled with ultrafine particles. (3) Deposition of 3 nm Au on base material A dispersion liquid in n-hexane was prepared in the same manner as in Example 5 to obtain a base material.
TiO as material₂Apply to the material and after drying
Heated for about an hour. As a result, the base material TiO ₂surface
Was uniformly coated with Au as a photoemission material.
A photoemission material is obtained.

At this time, it is preferable that Au to be deposited is not formed on the entire surface of the TiO ₂ surface, but is formed partially in, for example, a lattice or a stripe. Thereby, the action of TiO ₂ as a photocatalyst and the action of Au as a photoelectron emitting material can be simultaneously performed by irradiation of ultraviolet rays or the like.

(Embodiment 7) FIG. 8 relates to an application in which negative ions are discharged into a clean transport space to remove charges from a charged transported object. Glass substrate transfer device 43 provided with static elimination negative ion generator A integrated in the transfer path
FIG. In FIG. 8, negative ions 37 mainly include a photoelectron emitting material 33, an ultraviolet lamp 31, an electric field setting electrode 34 for emitting photoelectrons from the photoelectron emitting material 33,
UV-irradiation window glass 32, reflection surface 44 for UV radiation emitted from UV lamp 31, air supply fan 39, filter 40
Is generated in a negative ion generator A comprising: Air _{36 -1} in class 1000 clean room, air first by HEPA filter 40 from the fan 39 is dust, and clean air _{36 -3} particles have been removed.

The plate-shaped photoelectron emitting material 33 of this example is irradiated with ultraviolet rays from the ultraviolet lamp 31, and photoelectrons are emitted from the photoelectron emitting material. The photoelectrons emitted from the photoelectron emitting material 33 receive the action of the electrode 34 and move in the direction of the electrode 34, and are converted to negative ions 37 by the action of moisture or oxygen in the air _36-3 flowing therein. The negative ion 37
It is subjected to the action of the flow of air 36 _-3 flowing, negative ion rich air 36 _-2 released from the outlet of the negative ion generator A. Reference numeral 45 denotes a glass substrate being conveyed by the conveyance device 43, which is positively charged before static elimination (the position B), and
It has a potential of 00 to 3,500 V, but drops to 10 V or less after static elimination by the negative ion-enriched air (position C).

The ultraviolet lamp 31 of this embodiment is a sterilizing lamp. Since the photoelectron emission material 33 of the present invention exerts a photocatalytic action by irradiation with ultraviolet light, contaminants adhering to the material,
For example, hydrocarbons are decomposed and removed by a photocatalyst, and long-term stability can be maintained.

In the clean room, hydrocarbons, for example, phthalic acid esters, are harmful pollutants to the glass substrate (contamination of hydrocarbons into the glass substrate is a cause of electrical trouble or a decrease in surface wettability). However, since the photoelectron emission material 33 of the present invention decomposes and removes these contaminants, the dust and negative ion generator using the photoelectron emission material of the present invention removes particles and gas. Clean (no contamination of the substrate) negative ion enriched air is obtained.

The photoelectron emission material 33 in this example is
The TiO ₂ used in Example 6 was used, which was formed by applying and firing on an Al base material, and further coated with Au as a photoelectron emitting material.

(Embodiment 8) Class 1,000 of a semiconductor factory
The air purification in the small wafer storage (wafer storage stocker 52) installed in the clean room No. 0 will be described with reference to the basic configuration diagram of the wafer storage using the photoelectron emission material 33 of the present invention shown in FIG. I do. Wafer storage 52
The air cleaning is performed by an ultraviolet lamp 31, an ultraviolet reflecting surface 44, a photoelectron emission material 33, an electrode 34 for setting an electric field for photoelectron emission, and a material 46 for collecting charged fine particles, which are provided on one side of a wafer storage 52. It is implemented in. That is, the fine particles (particulate matter) 47 in the wafer storage 52 are charged by the photoelectrons (negative ions) 37 emitted from the photoelectron emitting material 33 irradiated with the ultraviolet rays from the ultraviolet lamp 31, and become charged fine particles. Particles are charged particle collecting material 4
6 (air purification section D).

As a result, the processing target space portion (cleaning space portion E) where the wafer exists is highly purified. Here, the light shielding material 48 is installed between the space to be processed and the air cleaning unit. The light shielding member 48 is provided to prevent the ultraviolet rays from the ultraviolet lamp 31 from irradiating the wafer carrier 39 and the wafer 50. Reference numeral 32 denotes an ultraviolet irradiation window glass.

The hydrocarbons (non-methane hydrocarbons) 51 in the wafer storage 52 are adsorbed on the surface of the photoelectron emission material 33, and are decomposed and made harmless by the catalytic action of the TiO ₂ irradiated with ultraviolet rays. In the wafer storage 52, the fine particles 47 (concentration: class 1,000) as harmful substances in the clean room and the contact angle when adhering to the wafer substrate each time the wafer 50 is put in and out of the storage 52 (opening and closing the storage). Organic gas 51 (non-methane hydrocarbon concentration:
1.0 to 1.5 ppm), but as described above, these harmful substances (fine particles and organic gas) are collected and removed, and contact is made in the clean air section (E) of the storage 52. An ultra-clean space that is cleaner than class 1 is created without causing an increase in the angle (0.2 ppm or less as a non-methane hydrocarbon concentration).

Here, reference numerals 36 _-1 and 36 _-2 indicate the flow of air in the storage. That is, since the air that has moved to the harmful substance processing section (D) is heated by irradiation of the ultraviolet lamp 31, an ascending air current is generated, and the inside of the storage A is indicated by arrows 3 and 3.
6 _-1, move as of _{36 -2.} Due to the movement of the air due to the natural environment, the organic gas 51 which increases the contact angle when attached to the fine particles 47 and the wafer substrate in the storage 52.
Move sequentially and effectively to the air cleaning section (D). In this manner, the inside of the storage 52 is quickly and simply cleaned, and the inside of the wafer storage becomes ultra-clean air, thereby significantly preventing contamination of the wafer.

In the above description, the photoelectron emitting material 33 is irradiated with ultraviolet light from the ultraviolet lamp 31 efficiently using the curved reflecting surface 44 by using the curved reflecting surface 44. The electrode 34 is provided for performing photoelectron emission from the photoelectron emission material 33 in an electric field. That is, an electric field is formed between the photoelectron emission material 33 and the electrode 34. The charging of the fine particles is efficiently performed by photoelectrons 37 generated by irradiating the photoelectron emitting material with ultraviolet light in an electric field. The voltage of the electric field here is 50 V / cm. The photoelectron emission material 33 of the present invention maintains stable performance for a long time as described above, and effectively removes hydrocarbons contaminating the wafer, so that particles and gas can be removed at the same time. It is a photoelectron emission material.

The procedure for manufacturing the photoelectron emitting material 3 will now be described. (1) The production of the ultrafine particles Au as the photoelectron emitting substance is based on the use of gold stearate as the metal organic compound, and is the same as that of the above-mentioned Example 5. (2) As in Example 5, a dispersion liquid of n-hexane was prepared, applied to a Ti material as a base material, and dried to form 250 nm of Au ultrafine particles of 3 nm particles on the base material. Heat for 3 hours. As a result, Au ultrafine particles having a particle diameter of 3 nm were uniformly fused and adhered to the Ti surface. (3) The conversion of the base material to TiO ₂ is performed by adding the Au-added Ti material to 800.
Calcination is performed in an oxygen-containing atmosphere at 1 ° C. for 1 hour. Thereby, in the Ti material to which Au is partially applied, a portion where Au is not applied is converted into TiO ₂ .

As a result, a composite material of a photoelectron emitting material and a photocatalyst in which Au having a particle diameter of 3 nm as a photoelectron emitting substance and TiO ₂ as a photocatalyst are respectively adhered to the surface of the Ti material of the base material is obtained.

(Embodiment 9) Embodiment 5 having the structure shown in FIG.
Introduce room air to the negative ion generator under the following conditions,
The photoelectron emitting material was irradiated with ultraviolet rays, and the transition of the negative ion concentration at the outlet of the negative ion generator in continuous operation was examined using a negative ion measuring device. (1) Size of negative ion generator; 30 × 30 × 60c
m, (2) As the photoelectron emitting material, the one shown in Example 5 was used. (3) UV lamp; germicidal lamp (254 nm) (4) Electrode; mesh [photoelectron emitting material (negative), electrode material (positive), 10 V / cm], (5) Dust removing filter; HEPA filter, (6) negative ion Concentration measuring device; Ion tester (0.4c
m ² / V. With electric mobility of S or higher)

FIG. 10 shows the measurement results for the number of days of the negative ion concentration. FIG. 10 shows, as a comparative example, the negative ion concentration in the case of using a photoelectron emitting material obtained by plating Au (1 μm in thickness) on TiO ₂ as a base material. That is, FIG.
In the figures, the photoelectron emitting material using the ultrafine particles of the present invention (average particle size: 3 nm) is indicated by-, and the photoelectron emitting material (plating) as a comparative example is indicated by-. As a result, it can be seen that the photoelectron emitting material of the present invention did not cause deterioration with the lapse of days and showed good results.

(Embodiment 10) The air (sample air) of a class 1,000 clean room in a semiconductor factory is stored in a wafer storage (stocker) of embodiment 8 having the configuration shown in FIG.
Was introduced, and the contact angle on the stored wafer and the concentration of contaminants in the air of the stocker were examined. The conditions are as follows. (1) Size of stocker; 100 liters (2) Photoemission material; Example 9 (3) Ultraviolet lamp; Sterilization lamp (4) Electrode for photoemission; Mesh, 50 V / cm (5) Collection of charged particles Material: SUS material, 850 V / cm (6) Clean room air; Fine particle concentration: Class 100
0 (7) Measurement method of contact angle on wafer; water drop contact angle meter (8) concentration of hydrocarbon in air; GC method (9) concentration of NH _{3 in} air; chemiluminescence method

The results of the measurement will be described below. First,
FIG. 11 shows the measurement results of the contact angles. In FIG.
−- indicates a value in the stocker of the present invention, and-●-indicates a comparative example in which the photoemission material of the present invention is not provided in the stocker.

Next, Table 1 shows the concentrations of hydrocarbons and NH ₃ in the air. Table 1 shows a comparative example in which the photoelectron emitting material of the present invention was not installed.

Table 1 The present invention Comparative Example Hydrocarbon concentration in stocker (ppm) <0.1 1 to 1.1 NH ₃ concentration in stocker (ppb) <130 to 32

As described above, when the photoelectron emitting material of the present invention is used, the contact angle hardly increases even after the lapse of days, and the hydrocarbon concentration and NH ₃ concentration inside the stocker are remarkable. Reduce.

[0131]

As described above, according to the first aspect of the present invention, a porous anodic oxide film having pores is formed on the surface of Al or an Al alloy, and an ultrafine photocatalyst material is formed in the pores of the film. Is filled. As a result, the surface area of the photocatalyst material is increased, and the irradiation light is efficiently absorbed by the photocatalyst material.
A photocatalyst that is lightweight and has a fast reaction rate can be obtained. In addition, (2) a photocatalyst capable of performing ultra-cleaning (having a high degree of cleanliness) in a short time can be obtained.

In the above case, the pores of the film are set to 10 to 200 nm, and TiO ₂ having a particle size of 1/10 or less of the size of the pores is used. The photocatalyst material can be efficiently filled into the pores. (2) Since the photocatalyst material to be filled is ultrafine TiO ₂ , the surface area increases and the photocatalyst material is firmly fixed in the pores, so that a photocatalyst that is mechanically stable and has high performance can be obtained. . Furthermore, (3) the light irradiated on the surface of the photocatalyst is reflected at the interface between the substrate and the anodic oxide film, so that the irradiated light is effectively absorbed by the photocatalyst material. That is, the irradiation light can be effectively used for the reaction (action) of the photocatalyst.

Further, by installing (or floating) the photocatalyst on the wall surface or in the space of the device for removing harmful components, a device for decomposing and removing harmful organic substances having a high reaction rate can be obtained. .

Further, according to a second aspect of the present invention, in a structure of a photoelectron emitting material obtained by irradiating a photoelectron emitting material with ultraviolet rays, a photoelectron emitting material having a particle diameter of 1 to 100 nm is disposed on a base material surface of the material. Things. This makes it possible to stably generate photoelectrons (negative ions) from the photoelectron emitting material for a long time.

In the production of the photoelectron emitting material of the present invention, ultrafine particles having a structure in which the metal organic compound is surrounded around the metal core by heat-treating the metal organic compound at a relatively low temperature in an inert gas atmosphere. The ultrafine particles having the metal core (metal is a photoelectron emitting substance) at the center are excellent in dispersion and stability, and become soluble when dispersed in a solvent. That is, the photo-emissive substance can be easily applied onto the base material of the photo-emissive material. By heating the applied base material, the metal of the metal core (photo-emissive substance)
Are uniformly arranged (coated) on the base material. Thus, the photoelectrons can be supplied stably at a high concentration.

Further, by using a photocatalyst as the base material of the photoelectron emitting material, gaseous pollutants (organic hydrocarbons) which adhere to the photoelectron emitting substance and cause deterioration in performance are decomposed by the action of the coexisting photocatalyst. It is processed. As a result, the photoelectron emission material can be stabilized for a long time to perform self-cleaning, and as a result, generation of photoelectrons (negative ions) from the photoelectron emission material is stabilized for a long time. Further, the photocatalyst decomposes and removes gaseous contaminants such as hydrocarbons and NH ₃ existing in a space such as a gas in normal air, so that clean negative ions can be obtained. Thereby, the effect of photoelectron emission is improved and stabilized, so that the generation of negative ions becomes effective (high performance and stable for a long time), and the practicality of the field using negative ions is improved.

In particular, the utility of the following field utilizing negative ions is improved. (1) The field of creating a comfortable working space for a living body that does not impair the metabolic and physiological functions of the living body. (2) The field of creating electrically safe spaces (spaces where neutralization of charged materials and neutralization can be performed). (3) The field of maintaining the freshness of food and preventing the growth of fungi. (4) Fields in which fine particles in a gas or space are charged and used, for example, a field for obtaining a purified gas or a clean space, a field for measuring fine particles, separation, classification, surface modification, and control of fine particles. Field.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an air cleaning system using a reaction device using a photocatalyst of the present invention.

FIG. 2 is a schematic configuration diagram of a stocker provided with a photocatalyst reaction device of the present invention.

FIG. 3 is a schematic configuration diagram of a water treatment apparatus equipped with a photocatalyst reaction device of the present invention.

FIG. 4 shows elapsed time (h), contact angle (degree), and adhesive force (m)
9 is a graph showing the relationship with N).

FIG. 5 is a graph showing the relationship between elapsed time and hydrocarbon concentration (HC).

FIG. 6 is a diagram showing a conventional air purifying apparatus using photoelectron emission.

FIG. 7 is a schematic configuration diagram showing a comfortable space provided with a negative ion generator using the photoelectron emitting material of the present invention.

FIG. 8 is a schematic configuration diagram showing a transfer space of an object to be processed provided with a negative ion generator using a photoelectron emitting material of the present invention.

FIG. 9 is a schematic configuration diagram showing a wafer storage provided with a clean air generator using a photoelectron emitting material of the present invention.

FIG. 10 is a graph showing the relationship between elapsed time and negative ion concentration.

FIG. 11 is a graph showing the relationship between elapsed time (h) and contact angle (degree).

[Explanation of symbols]

Reference Signs List 1 clean room 3 harmful gas generated 4,52 stocker 9 photocatalyst 10,31 ultraviolet lamp 11,36 air to be processed 12,36 _-3 clean air 14,50 wafer 20 water treatment device 33 photoelectron emission material 34 electrode 37 negative ion

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G069 AA03 AA08 BA04A BA04B BA48A BB04A BB04B BC16A BC16B CA01 CA05 CA10 CA15 CA19 DA05 EA04Y EA11 EA18 EB18X EB18Y EC14Y ED04 FA02 FA04 FB18 FB34 FB42 FB58 FB58

Claims (5)

[Claims] A porous anodic oxide film formed on the surface of Al or an Al alloy has a particle diameter of 1 to 100 n as a photocatalyst material.
A photocatalyst, wherein m is filled with TiO ₂ . 2. A photoelectron emitting material that emits photoelectrons by irradiating ultraviolet rays, wherein the emitting material is 1 to 100.
A photoelectron emitting material comprising a base material and a photoelectron emitting material having a particle size of nm. 3. The photoelectron emitting material according to claim 2, wherein the base material of the photoelectron emitting material is a TiO ₂ material. 4. The photocatalyst according to claim 1 is used as a photocatalyst, and / or the photoelectron emitting material according to claim 2 is used as a photoelectron emitting material, and the photocatalyst and / or the photoelectron emitting material is irradiated with light. A reaction apparatus, comprising: a light irradiation unit for performing the reaction. 5. The light irradiation means has at least 254n.
The reactor according to claim 4, comprising a light source of ultraviolet light having a wavelength of m.