JP2001191042A - Surface cleaning method, surface cleaning device, steam generator, photocatalyst container, photocleaning surface of object for cleaning, photocatalyst surface forming method, photocatalyst surface forming device and photocatalyst surface device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To 'highly clean' surfaces to molecular and atomic levels and to maintain the cleanliness of the surfaces at <=1012 molecule/cm2. SOLUTION: The surface cleaning method having a first step of injecting photocatalyst steam to the surface of an object for cleaning and a second step of irradiating the surface of this object for cleaning with light including UV rays is provided. The steam generated from a pure water dispersion of titanium oxide is adopted for the photocatalyst steam of the first step and the surface of the object for cleaning is irradiated with the light including the UV rays for the second step, by which the surface of the object for cleaning may be 'highly cleaned' to the molecular and atomic levels.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the development of photocatalytic technology that solves the problem of resources and the environment. That is, the present invention relates to a technology for forming a photocatalytic surface that is resource-saving and harmless to the environment. The surface is a surface that is to be cleaned and cleaned periodically.
For consumer use such as various vehicle surfaces, interiors of buildings and structures, surfaces of furniture and windows, surfaces of display devices such as liquid crystal panels and TV screens, surfaces of personal computers, telephones, office equipment, everyday equipment and equipment And a wide range of industrial fields.

[0002] The present invention further relates to a surface of a material constituting a clean atmosphere, a device and a part operating in a clean atmosphere, and a “molecular-level purification technology” for the surface of the material. It is suitable to be applied to a wide range of technical fields such as a semiconductor and liquid crystal field, a magnetic disk field, an optical device field, a medical field, a medical field, and a precision measurement field.

[0003]

2. Description of the Related Art The development of surface cleaning technology using a photocatalyst is rapidly expanding and progressing. For example, ceramic products whose surface has been made hydrophilic with a photocatalyst layer have been commercialized,
Window panel photocatalytic coatings are also becoming more widespread.

[0004] The cleaning technology currently being developed is an industrial cleaning technology. No technology has been developed from the viewpoint of cleaning the surfaces of devices, components and materials at the molecular level.

An object requiring surface purification at the molecular level will be described. The surface of a clean atmosphere constituent material, devices and components operating in a clean atmosphere, and the surface of the material are required to be purified at the molecular level. Hereinafter, the specific objects will be described.

First, the surface of the material constituting the clean atmosphere is required to be cleaned at the molecular level. When a clean air atmosphere is formed in a clean room, a clean bench, a clean booth, or the like, the surface of a duct, a wall, a curtain, a floor, and other materials constituting the surface becomes a problem. When a high-purity gas atmosphere is formed in a closed chamber, a transfer chamber, or the like, the surface of a material forming the chamber becomes a problem.

Second, devices, parts, and materials thereof are required to be cleaned at the molecular level. The equipment, components and materials that need to operate in a clean atmosphere are in fact themselves sources of contamination. It is inevitable from being processed, assembled, and manufactured in an atmosphere that is not clean. As a material,
In addition to metals, ceramics, and resins, there are various types such as new ceramics such as carbide, nitride, and boron, amorphous, crystalline, and sintered bodies. As the shape,
Examples include complex shapes, blind hole shapes, and gap shapes.

[0008]

Recently, various photocatalytic coating techniques have been developed. Techniques include formulation of a compounding agent for obtaining the dispersibility and stability of titanium oxide as a photocatalyst and a coating method for obtaining durability and robustness.
However, the inventors note that a photocatalytic coating technique that satisfies the following two viewpoints is needed in the future.

General versatility and simplicity In other words, the conventional photocatalytic coating technology is unique for each target surface, has no general versatility, and has no simplicity because it is intended for durability. For the majority of surfaces to be cleaned, it is desirable that the surface can be easily and quickly cleaned, and that it be a mobile and regenerative means.

Resource Saving and Environmental Responsiveness The more widely applied photocatalytic coating technology, the greater the resource consumption and environmental impact of the technology. Now, photocatalyst technology is being generalized to a wide range of fields without being limited to special targets. This technology field has entered an era where resource saving and environmental responsiveness are strongly required. From the above viewpoints, the problems of the related art are extracted.

1. Problems with Photocatalytic Coating Agents Various formulations of photocatalytic coating agents have been developed with the aim of coating surface stability and durability. However, the performance of the coating agent is not all stability and durability. Regardless of the material and properties of the surface, a versatile coating agent that does not cause any change in the surface is often required. In the conventional coating agent, various chemical components such as an acid / alkali and a surfactant are compounded in order to disperse the photocatalytic titanium oxide. Corrosion on various surfaces
It is difficult to seek versatility that does not alter the quality. Further, since durability is intended, there is no function of washing with water and regenerating as needed. The responsibilities of the coating components for their impact on resources and the environment have not yet been considered.

2. Problems of Coating Method As a coating method, a spray method of a coating agent solution is well known. Various spray methods have been employed. However, when looking at existing spray systems from a resource and environmental point of view, there are problems of large consumption of the coating agent solution and contamination of the surrounding environment.

For example, a method has been proposed in which a coating agent is an aqueous solution containing a neutral organic titanium compound and containing alcohol, and this is sprayed on a target surface. Although excellent as a coating method, there are problems in terms of resources and environment. The surface adhesion rate of titanium oxide particles per amount of sprayed water is small, and most of the solution is discarded. Environmental measures for this drainage are necessary.

Further, with respect to cleaning at the molecular level, the conventional method has not been able to obtain a clean surface through the process of constructing the apparatus, parts and materials thereof. For example, it is difficult to obtain a cleaned surface at a molecular level by a cleaning means that depends on the action of chemicals.

That is, in a field that requires molecular-level cleaning, surface cleaning cannot be achieved by conventional cleaning techniques. The present inventors intend “purification-” instead of “cleaning-”. This is because the level of cleanliness of the general cleaning technology and the level of cleanliness in the technical field requiring a completely cleaning surface are completely different. Table 1 shows the differences in surface cleanliness levels.

[0016]

[Table 1]

General cleaning is a technique that reaches a level from the level shown in Table 1. For example, on the surface of a metal material, the roughness of the mechanically polished surface is several tens of μm, and the machining oil adheres to a level of several mg / cm ² . Even when the surface roughness is reduced to about 10 μm by chemical polishing
It adheres to the level of mg / cm ² . Departure from this level removes about three orders of magnitude and reaches the level where the cleaning objective has been achieved. In the general industrial field, there is no problem in considering this surface to be clean.

On the other hand, in the industrial field dealing with completely purified surfaces, the levels shown in Table 1 are starting points. The presence of several molecular layers of contaminant molecules means that molecules and atoms of the substrate are not present on the surface, and loses the meaning of making the surface function. Purification is a technique that reduces contamination by about three orders of magnitude from the level to reach the level. Nevertheless, depending on the type of contaminant molecules, there may still be problems with the surface operation mechanism. In the future, purification will be required to reach levels about four orders of magnitude lower (10 ⁻⁶ to 10 ⁻⁷ molecular layers). In the present specification, “Precise Cleaning-” on the surface of molecules and atoms is referred to as “Purification-Purific”.
ation- ”.

There is also a problem that covers all processes from component processing to device assembly. As an example, the issues in the semiconductor manufacturing field, which are continuing technical development based on the generation update of the degree of fine processing, will be described.

The atmosphere of a semiconductor manufacturing apparatus is required to have a stricter degree of cleanliness with respect to organic substances, and measures are taken. However, there is a problem that the apparatus itself is a source of organic substances, and this is difficult to solve. Parts constituting the apparatus are composed of various surface states and complicated shapes such as cast products, forged products, and machined products. There is no cleaning technology that can completely remove the processing contamination of parts having complicated shapes or blind holes.

For example, when a cleaning agent is used, problems such as residual cleaning material and adsorption occur. On the other hand, baking heat treatment is an effective purification method, but it is limited to heat-treatable materials. Even in the case of metal parts, it is often impossible to implement the method because the shape and dimensional accuracy is impaired. Even if the machined parts can be cleaned, they are subsequently contaminated by the atmosphere during storage, and are contaminated by the atmosphere and handling during assembly.

The problem to be solved is not merely a component cleaning technique. There is a need for "all process purification technology" covering all processes such as a component processing process, a post-processing cleaning process, a storage process, an assembly process, and a cleaning and finishing process of an assembly device.
The situation is the same in the precision industrial field other than semiconductor manufacturing.

As described above, although various photocatalytic coating techniques have been conventionally proposed, the versatility is poor because the coating target is narrow and limited for each technique.
Along with this, there is also a problem with environmental compatibility, which is a recent strong demand. Furthermore, despite the urgent need for photocatalyst technology that contributes to molecular-level purification, there is currently no existing technology.

The present invention is to solve such a problem.
The cleaning target is limited to specific ones
Expanding to as wide a field as possible without saving resources and environment
Simple and quick reliable surface cleaning while ensuring compatibility
Planning and the surface of the object to be purified at the molecular and atomic level
To "clean purification" and a surface cleanness of 10¹²Molecule / cm ^Two
A surface purification method, a surface purification device,
Light purification table of water vapor generator, photocatalyst container, object to be purified
Surface, photocatalytic surface forming method, photocatalytic surface forming apparatus, and photocatalyst
It is an object to provide a medium surface device.

[0025]

According to a first aspect of the present invention, there is provided a method of cleaning a surface, comprising the steps of: injecting photocatalytic water vapor onto the surface of the object; and irradiating the surface of the object with light containing ultraviolet rays. And the following steps.

In one embodiment of the surface cleaning method according to the present invention, before the first step, there is further provided a third step of purifying the surface of the object to be purified by injecting water vapor.

In one embodiment of the surface cleaning method of the present invention, the object to be purified is a material constituting a clean atmosphere, an apparatus and parts operating in the clean atmosphere, and a material thereof.

In one embodiment of the surface cleaning method of the present invention, the irradiation with the light containing the ultraviolet rays is performed while the object to be cleaned is being stored, assembled, or operated.

In one embodiment of the surface cleaning method of the present invention, after the second step, there is further provided a fourth step of injecting water vapor onto the surface of the object to be purified to obtain a photocatalyst removal surface.

In one embodiment of the surface cleaning method of the present invention, the ultraviolet light is a light in the near ultraviolet region having a wavelength in the range of 300 nm to 400 nm.

In one embodiment of the surface cleaning method of the present invention, the ultraviolet rays are ultraviolet rays having a wavelength in the range of about 180 nm to 300 nm.

In one embodiment of the surface cleaning method of the present invention, the photocatalytic steam is steam generated from a titanium oxide pure water dispersion, and the steam contains fine titanium oxide particles.

In one embodiment of the surface cleaning method of the present invention, the dispersion of titanium oxide in pure water has a particle diameter of 2 nm to 3 nm.
Contains titanium oxide having a hydrophilic surface of 00 nm and does not contain other components.

The surface cleaning apparatus of the present invention includes an ultraviolet irradiation means for irradiating a photocatalyst surface formed on the surface of the object to be purified with light containing ultraviolet light, and the surface of the object to be purified is purified by the irradiation of the ultraviolet light. I do.

[0035] The surface purification apparatus of the present invention comprises: a steam injection means for purifying the surface of the object to be purified by steam injection;
A light-steam injecting means for causing the surface of the object to be purified to be the photocatalyst surface by means of the light-steam injection of the steam.

[0036] The surface purification apparatus of the present invention comprises a steam injection means for purifying the surface of the object to be purified by water vapor injection, a light steam injection means for making the surface of the object to be purified a photocatalyst surface by photocatalyst water vapor injection, Ultraviolet irradiation means for irradiating the surface with light containing ultraviolet light.

The steam generator of the present invention has first switching means for switching between steam injection and photocatalytic steam injection, and second switching means for switching between saturated steam injection and superheated steam injection. The predetermined steam determined by the first and second switching means is injected.

The photocatalyst container of the present invention comprises a closed container provided with an ultraviolet lamp, and irradiates the surface of the object to be purified with the photocatalyst surface housed therein with ultraviolet light.

The light-purifying surface of the object to be purified according to the present invention is obtained by converting the surface purified by steam treatment into a photocatalytic surface by photocatalytic steam treatment and irradiating the surface with near-ultraviolet rays.

In one embodiment of the light purification surface of the object to be purified of the present invention, the photocatalyst surface is obtained by irradiating the surface of the photocatalyst with ultraviolet rays and then removing the surface photocatalyst by steam treatment.

In the method for forming a photocatalyst surface of the present invention, photocatalyst water is sprayed on the treated surface in a mist state, and the fine particles of the photocatalyst water are attached to the surface.

In one embodiment of the photocatalyst surface forming method of the present invention, the photocatalyst water is a pure water dispersion in which the fine particles are titanium oxide.

In one embodiment of the method for forming a photocatalyst surface according to the present invention, the concentration of the fine particles in the photocatalytic water is 0.01%.
It is a value in the range of g / L to 100 g / L.

The photocatalyst surface forming apparatus of the present invention is provided with a spraying means having a nozzle for spraying the photocatalyst water in a mist, spraying the photocatalyst water from the nozzle onto the surface to be treated, and applying the fine particles of the photocatalyst water to the surface. Attach.

In one embodiment of the photocatalyst surface forming apparatus of the present invention, the photocatalytic water is a pure water dispersion in which the fine particles are titanium oxide.

In one embodiment of the photocatalyst surface forming apparatus of the present invention, the concentration of the fine particles in the photocatalytic water is 0.01
It is a value in the range of g / L to 100 g / L.

In one embodiment of the photocatalyst surface forming apparatus according to the present invention, the spraying means sprays the photocatalyst water at room temperature from the nozzle onto the processing surface by air pressure.

In one embodiment of the photocatalyst surface forming apparatus according to the present invention, the spraying unit sprays the photocatalytic water as steam from the nozzle onto the processing surface.

In one embodiment of the photocatalyst surface forming apparatus of the present invention, the spraying means comprises a first steam spray mechanism for spraying steam of the photocatalytic water, and a second steam spray mechanism for spraying steam of pure water. The first steam spray mechanism switches the spray between the saturated steam and the superheated steam.

The photocatalyst surface device of the present invention has a surface on which fine particles in the photocatalyst water adhere by spraying of the photocatalyst water.

Specific examples of the photocatalyst surface device include a substrate transport device for transporting a substrate, which is used in the manufacture of semiconductor devices and liquid crystal devices, an optical device having an optical system,
It is suitable for application to a clean atmosphere device for cleaning the atmosphere.

[0052]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. As a new photocatalyst surface forming means that solves the two problems of versatility and simplicity, resource saving and environmental friendliness, the present inventors have used pure water dispersion containing no other components other than titanium oxide as solute fine particles. We developed a method of spraying it at room temperature and water vapor on the surface of the object to be purified.

Hereinafter, 1. 1. Photocatalytic water treatment; 2. Resource and environmental effects; 3. Purification effect by pure water vapor; 4. The effect of purifying the photocatalyst water treatment surface with ultraviolet rays; 5. Contents of purification device, 6. Means for purification of all processes, 7. Various photocatalytic surface materials provided by this technology; The photocatalyst surface device will be described sequentially.

1. First, the photocatalytic water treatment will be described. Regarding the photocatalyst water treatment, (1) photocatalyst titanium oxide used for photocatalyst water treatment, (2) pure water dispersion solution of photocatalyst titanium oxide, (3) spray of photocatalyst water, (4) generation of photocatalyst steam, (5) Each item will be described in the order of spraying of the photocatalyst steam and (6) the particle adhesion rate of the photocatalyst steam spray.

(1) Titanium oxide photocatalyst The titanium oxide photocatalyst has a particle diameter of 2 nm to 300 nm.
Is used. It is known that titanium oxide having an anatase crystal structure has strong catalytic activity. The titanium oxide particles have a hydrophobic surface. In order to disperse the titanium oxide particles in pure water, the surface of the titanium oxide particles is made hydrophilic. A hydrophilic surface is needed to disperse wet in water. It is known that the surface of titanium oxide becomes hydrophilic by light irradiation. It is also known that silica having a hydrophilic surface can be made hydrophilic by disposing it on the titanium oxide surface. Any of these means may be used, or other hydrophilic means may be used.

(2) Pure Water Dispersion Solution of Titanium Oxide Photocatalyst Generally, an aqueous dispersion solution of titanium oxide is prepared using additives such as an acid, an alkali and other dispersants and surfactants. However, such a conventional aqueous dispersion cannot be used for the purpose of forming a completely purified surface. In this embodiment, a pure water dispersion of hydrophilic surface titanium oxide particles is used, and no other components are contained. In this embodiment, a dilute dispersion of titanium oxide is used for the purpose of forming the photocatalyst surface by photocatalytic steam treatment. Conventional titanium oxide dispersions are often used at a concentration of several tens of percent, but have a dilute concentration of about several orders of magnitude. These conditions are advantageous for preparing a pure water dispersion solution without any additives.

As shown in Table 2, the particle diameter was 7 nm to 2 nm.
When it is 0 nm, the titanium oxide concentration of the aqueous dispersion solution is 1 g.
/ L (0.1 wt%) even at a dilute concentration,
10 ¹⁷Pieces / L-10¹⁸It can be seen that the number is L / L.

[0058]

[Table 2]

(3) Spraying of Photocatalyst Water A mist of photocatalyst water is generated by a pneumatic spray method using a pure water dispersion of titanium oxide. The method of generating the mist of the photocatalytic water is a method of intermittently spraying the liquid by manually moving the spray nozzle up and down by using a spray bottle, a method of continuously introducing the liquid from the spray nozzle by introducing compressed air into a closed container, and any other method. Means may be used.

(4) Generation of Photocatalytic Water Vapor Photocatalytic water vapor is generated using a titanium oxide pure water dispersion. According to the steam generation method described later, all the titanium oxide particles in the titanium oxide pure water dispersion are included in the steam. As shown in Table 3, the water is about 1700 times that of water vapor by volume, oxidation number of titanium particles of photocatalyst steam is about 10 ¹⁸ / 1700L (water vapor).

[0061]

[Table 3]

(5) Spraying of Photocatalyst Water Vapor Photocatalyst water vapor is sprayed to form a surface to which titanium oxide is attached. In order to make the surface of the photocatalyst, adhesion of the single particle layer is sufficient. Table 4 shows the calculated values of the number of particles in the pure water dispersion and in the water vapor necessary for forming the titanium oxide single particle layer on the surface.

[0063]

[Table 4]

From Table 4, it is found that the amount of water vapor of the photocatalyst corresponding to the titanium oxide single particle layer per unit surface area is about 30 L / m ² , and the amount of the pure water dispersion required for generating the water vapor is 17.6.
(1 mL of water is 1.7 L at 100 ° C. water vapor).

Here, when the titanium oxide concentration in the pure water dispersion is further reduced (0.1 g / L), the number of particles in the pure water dispersion and the number of particles in the water vapor necessary for forming a single particle layer are determined. Table 5 shows the relationship between and the number of particles on the spray surface.

[0066]

[Table 5]

Table 5 shows that about 100 mL of water vapor per unit area (cm ² ) is required to form a titanium oxide single particle layer on the surface. Titanium oxide concentration 0.
When 1 g / L of a pure water dispersion is used and the amount of photocatalytic water vapor generated by the water vapor generator is about 1 L / second, titanium oxide particles necessary to form a surface single particle layer per ^{second in} an area of about 10 cm ² are formed. Will be injected. The relationship between the amount of particles injected and the amount of particles attached varies depending on the surface to be treated, but a single particle layer of titanium oxide is usually formed on the surface within a few seconds of injection time.

Generation rate of photocatalyst steam: The amount of photocatalyst steam generated per hour can be arbitrarily selected depending on the heating capacity of the steam generator. For example, the time for generating the photocatalyst water vapor amount of 30 L in Table 4 is when the water vapor amount of the water vapor generator is 0.1%.
L / min (approximately 1.7 mL / sec) is about 10 seconds.
In order to increase the surface adhesion rate of the particles, it is possible to adopt a condition in which the steam generation rate is further reduced and the spraying time is lengthened, and conversely, a condition in which the steam generation rate is increased to shorten the processing time is adopted. It goes without saying that this may be done.

(6) Particle Adhesion Rate of Photocatalyst Water Vapor Spray Table 6 shows the surface adhesion rate of titanium oxide particles by atomization or water vapor spray. This is compared with the surface adhesion ratio when the aqueous dispersion is directly sprayed on the surface.

In the case of spraying a mist of photocatalyst water A pure water dispersion of titanium oxide was sprayed as mist from a nozzle using compressed air. Treated surface: 1 m ² (circumference surrounded by curtain) Spray nozzle: Approximately 1 m above the treated surface Compressed air volume: 0.5 L / sec Spray volume: Titanium oxide pure water dispersion 0.0025 L / sec Spraying time: 10 seconds

In the case of the spraying of the photocatalytic steam system The steam generated from the titanium oxide pure water dispersion is applied to the treated surface.
Sprayed. Processing surface: 1m^Two(Surrounded by curtains
State) Spray nozzle: About 1m above the treated surface Water vapor amount: Generated from 0.025L of titanium oxide pure water dispersion
43L of water vapor ^TwoSpray time on the treated surface Spray time: 10 seconds

[Surface Adhesion Rate] In both cases, a titanium oxide single particle layer (2.0 × 10 ¹⁶ particles / m ² ) was obtained on the treated surface. The amount of the titanium oxide pure water dispersion used was the same, and in each case, about 60.0% of the particles in the liquid adhered to the surface. That is, since the mist containing the titanium oxide particles settles on the surface, it adheres almost without loss. This is because, in the case of the comparative photocatalyst aqueous solution injection, the surface adhesion rate is extremely low. This is because the jetting force of the aqueous solution simultaneously becomes the peeling force of the adhered particles.

Here, an appropriate value of the titanium oxide concentration will be described. The current commercially available titanium oxide concentration is 30% to 4%
0% (300 g / L to 400 g / L),
It is considered that a slightly lower concentration is preferable as the upper limit. In this example, the titanium oxide concentration was exemplified as 1 g / L. However, as described above, it is considered that about 0.1 g / L is sufficient, and it is suggested that the titanium oxide concentration can be applied even at a lower concentration. The concentration is preferably a value within the range of 0.01 g / L to 100 g / L.

[Dispersion state of surface-adhered particles] When the dispersion state of surface-adhered particles is observed by SEM, the dispersion state is more uniform than in the case of. It can be seen that the titanium oxide particles are better dispersed in the water vapor state than in the atomized state.

[0075]

[Table 6]

2. Next, resources and environmental effects will be described. From the results shown in Table 6, the amount of water for obtaining the surface of the photocatalyst and the amount of titanium oxide are several orders of magnitude or less as compared with the conventional aqueous solution injection method, and the photocatalyst water spray method has large economic and resource effects. In addition, the conventional titanium oxide dispersion aqueous solution contains acids, alkalis, organic chemicals, surfactants, etc. and requires drainage measures, but the photocatalyst water spray method does not contain any additives. Not required.

3. Next, the effect of purification by pure water vapor will be described. As pretreatment of photocatalytic steam treatment,
Perform surface purification by pure water steam treatment. The effect of this pure water steam treatment will be described.

It is unavoidable that the component processing step becomes a contamination step. Contamination from machining oils should be removed immediately after processing. After the lapse of days, the processing oil is oxidized, deteriorated and deteriorated, and cleaning becomes difficult. Steam treatment is
It is a cleaning means that can be implemented at the parts processing site, and is very effective. By the steam injection processing, processing oil having a complicated shape or a blind hole shape can be removed.

Table 7 shows the effect of processing oil removal by steam injection. The amount of oil adhesion was reduced by about three orders of magnitude by
It is reduced to about a monolayer in seconds. The adsorption layer of a monolayer is
Since it has adsorption energy, it is difficult to remove it by pure water steam treatment. It can be purified by the following photocatalytic treatment.

[0080]

[Table 7]

4. Subsequently, the effect of purifying the photocatalytic water treatment surface with ultraviolet light will be described. Table 8 shows the effect of removing organic substances adhering to the surface when the surface of the photocatalyst formed by the photocatalytic steam treatment is irradiated with an ultraviolet lamp.

[0082]

[Table 8]

As shown in Table 8, the surface of the photocatalyst is purified with the progress of the ultraviolet treatment.

5. Next, the purifying device will be described. The purifying device is constituted by the following devices (1) to (5). Steam generator for steam processing and photocatalytic steam processing Steam processor Simple steam generator Near-ultraviolet irradiation device Photocatalyst container Each of these devices will be described below. Here, the surface purification device according to the present embodiment includes the above-described steam generation device and the steam treatment device, and FIG. 1 is a schematic diagram showing both the configurations of the steam generation device and the steam treatment device.

(1) Steam Generator FIG. 1 illustrates a principle diagram of a steam generator. An evaporator 1 and an evaporating heating block 2 for generating saturated steam,
A superheater 3 for generating superheated steam and a heating block 4 for superheating include a constant flow pump 5 and a pressure control needle valve 6.
Placed between. The internal pressure of the steam generation system is measured by a pressure gauge 7. The saturated steam temperature and the superheated steam temperature are measured by thermometers 8 and 9. The heat transfer area of the evaporator 1 is designed to satisfy the burnout point condition of the boiling characteristic curve.

In the case of simply treating with 100 ° C. saturated steam, that is, when generating steam at normal pressure, a heating block 2 for evaporation, a superheater 3 for generating superheated steam,
Overheating heating block 4 and pressure control needle valve 6
Is unnecessary.

Switching between pure water steam and photocatalytic steam: The valve 10 for the ultrapure water line is opened when steam of the ultrapure water is generated, and the valve 11 for the pure titanium oxide dispersion line is opened when steam containing the photocatalyst is generated.

Switching between saturated steam and superheated steam: Saturated steam and superheated steam are used for the case where there is no problem using steam containing mist (saturated steam) and the case where the surface is not wetted or the surface is to be dried. Switch. When the saturated steam is supplied, no heat is supplied to the heating block 4 for superheating. At this time, the superheater 3 simply serves as a steam passage. When superheated steam is supplied, heat is supplied to the heating block 4 for superheating, and the superheater 3 superheats the heating block. This produces mist-free dry steam.

Switching between steam spraying and steam spraying: When spraying steam on the processing surface 16, the spray valve 12 is opened. When injecting steam to the processing surface, the steam injection valve 13 is opened, and steam is injected from the steam injection nozzle 14 to the processing surface 16. In the case where the steam spraying or spraying process is performed in an enclosure instead of in an open state, a processing chamber 15 as illustrated may be used.

Table 9 shows examples of the control conditions of the steam supply.

[0091]

[Table 9]

(2) Steam treatment device Switching between pure water steam treatment and photocatalyst-containing steam treatment: In FIG. 1, the ultrapure water line valve 10 is opened during pure water steam treatment, and titanium oxide pure water Open the line valve 11.

FIG. 1 shows the steam injection nozzle 14, the processing chamber 15, and the processing surface 16. Steam injection nozzle 1
4, the processing surface 1 arranged in the processing chamber 15
6. Inject steam into 6.

(3) Simple type steam generator A small-sized handy type steam generator available on the market can be used. Although the humidity is limited to 100 ° C. or less, it can be used without any trouble in pre-cleaning and generation of photocatalytic water vapor.

The water vapor injection amount, the nozzle shape, and the injection linear velocity of the water vapor injection nozzle are arbitrarily selected depending on the object. Table 10 shows examples of nozzle conditions.

[0096]

[Table 10]

(4) Ultraviolet Irradiation Apparatus Two types of ultraviolet irradiation apparatuses will be described depending on the difference in the wavelength of the irradiated light beam.

Natural light / illumination light: Natural light and illumination light such as fluorescent light contain near-ultraviolet light, so that a photocatalyst can act. Near-ultraviolet lamp having a wavelength of 300 nm to 400 nm: A near-ultraviolet lamp having a wavelength range of 300 nm to 400 nm used for a moth lamp or the like is used. UV irradiation device having a wavelength of 185 nm to 300 nm: In an inert atmosphere such as nitrogen, the wavelength is 185 nm to 30 nm.
A lamp that emits 0 nm ultraviolet light is used. Irradiation with a lamp in this wavelength range in an air atmosphere produces ozone. When it is desired to use ozone, a lamp in this wavelength range is used while controlling the ozone atmosphere.

In an air atmosphere, ultraviolet rays having a wavelength of 185 nm or less have a transmission distance of 10 nm or less, and are not practical.

(5) Photocatalyst Container FIG. 2 shows a principle diagram of the photocatalyst container. Parts storage container 2
0, consisting of a component storage basket 21 and a near-ultraviolet lamp 22 inserted therein. The inner surface of the component storage container 20 is made a photocatalytic surface by photocatalytic steam treatment. When the near-ultraviolet lamp 22 is turned on, heat convection is formed in the container. Organic matter on the surface of the shadow of the irradiation light is also vaporized by the thermal convection and decomposed by the photoreaction. The surfaces of the devices, parts and materials contained in this container are purified. The photocatalyst container is desirably a closed container.

6. Next, a description will be given of a technology for purifying all processes using photocatalytic steam. The purification process is configured consistently for all process areas described below. Steam purification in parts processing process Photocatalyst activation of parts and material surfaces Acceleration of purification by photocatalyst container in parts storage process Photocatalyst purification in device assembly process Photocatalytic purification after device assembly Thus, the order of the above means is arbitrarily changed. In addition, when the inner surface of the device may be the photocatalyst-adhering surface,
Is omitted. Hereinafter, each of these steps will be described.

(1) Steam Purification in the Parts Processing Step Pure water vapor is injected onto the surface of the part immediately after machining. In particular, machine oil adhering to screw holes and narrow structural gaps is sprayed and removed. Store, store and transport in closed container.

(2) Activation of Photocatalyst on Parts and Material Surfaces Water vapor is sprayed onto the surface of the parts and the material surface which have been cleaned. The parts and materials that have been subjected to the photocatalyst activation treatment are stored and stored in the near-ultraviolet lamp insertion / sealing container described below.

(3) Acceleration of Purification by Photocatalyst Container in Parts Storage Step FIG. 2 shows an example of the photocatalyst container. The inner surface of the container has been subjected to a photocatalytic steam injection treatment. Parts and materials are stored in a storage basket surrounding a near-ultraviolet lamp inserted near the center. The near-ultraviolet lamp irradiates the inner surface of the container, the parts, and the material surface. The air in the container is always purified by photodecomposition of organic matter on the irradiation surface of the near-ultraviolet lamp and thermal convection of the air in the closed container by the near-ultraviolet lamp. Parts that are shadowed by the near-ultraviolet lamp and organic substances on the material surface are also removed by the vaporizing action and the air purifying action.

(4) The work of assembling the photocatalyst purification parts in the apparatus assembling step is performed while irradiating a near-ultraviolet lamp.

(5) Photocatalytic purification after assembling the device After assembling the device, a near-ultraviolet lamp is set inside the device, and ultraviolet light is irradiated.

(6) Photocatalyst purification during operation of a device An apparatus capable of irradiating ultraviolet rays during operation continues irradiation of ultraviolet rays.

(7) Formation of Photocatalyst Removal Surface by Spraying Water Vapor If the titanium oxide colloid particles adhere to the inner surface of the device, which is inappropriate for the purpose of use of the device, the inside of the device is purged with steam after the elapse of the device purification time. A spray treatment removes titanium oxide particles from the surface.

7. Next, the photocatalyst surface material will be described. By spraying the photocatalyst steam, various material surfaces can be used as photocatalyst surfaces. These photocatalytic surface materials
A clean surface is always maintained under illumination of lamps containing ultraviolet light or general fluorescent lighting, and under natural light if conditions permit. As a result, the atmosphere composed of these photocatalytic surface materials can always maintain high cleanliness. The photocatalyst surface material is illustrated below.

(1) Clean atmosphere material surface Clean room constituent materials: air duct materials, wall materials, ceiling materials, curtain materials and clean wear, clean gloves, etc. Clean bench constituent materials: air duct materials, wall materials, window materials, etc. Clean chamber Constituent materials: Chamber wall materials, component materials Clean transport tunnel Constituent materials: Duct materials

(2) An apparatus operating in a clean atmosphere
Parts and their materials Semiconductor devices, liquid crystal display devices: parts such as process chambers, lithography equipment, performance inspection devices, wafer carrier boxes, etc.Material magnetic disk devices: parts such as sputtering equipment, clean surfaces of disk substrates, magnetic disk carrier boxes, etc. ,
Materials Optical equipment: parts such as optical system optical paths, lenses, window plates, masks, reticles, and optical path parts boxes, materials Medicine and pharmaceutical equipment: parts and materials such as pharmaceutical manufacturing equipment, pharmaceutical boxes and pharmaceutical inspection equipment, measuring equipment: precision equipment Parts, materials such as precision parts, precision parts boxes, etc. These means can be used in various embodiments.

The surfaces are all surfaces that one wishes to periodically clean and clean. Various vehicle surfaces, interiors of buildings and structures, surfaces of furniture and windows, surfaces of display devices such as liquid crystal panels and TV screens, personal computers, telephones, office equipment,
It covers the surface of everyday equipment and supplies.

8. Finally, the photocatalyst surface device will be described. A photocatalyst surface device, that is, a device having a surface with fine particles of the photocatalyst attached by spraying photocatalytic water,
A clean apparatus surface and apparatus atmosphere can be always maintained under irradiation of light including ultraviolet rays. Hereinafter, specific examples of the photocatalyst surface device will be described.

(1) Substrate Transfer Device in Semiconductor Manufacturing As the substrate transfer device, there are a transfer duct, a transfer box, a substrate transfer device attached to a process chamber, and the like. There is a serious problem that a semiconductor / liquid crystal substrate that is processed in a strictly clean process atmosphere is contaminated with organic substances during the transportation process and its performance is deteriorated, and a photocatalytic surface device is required.

(2) Optical device As an optical device, a lens constituting device such as a photographing device and a projection device, a photometer for vacuum ultraviolet to ultraviolet spectroscopy, a semiconductor device,
2. Description of the Related Art There is an exposure apparatus for fine processing used in manufacturing a liquid crystal device.

An optical device composed of an optical lens system, an optical path system composed of a light transmitting window plate and an optical path system drive-control device, a mechanical system such as components, and an electric system, when a sealed type is used, is a source of internal contamination sources. There is a problem that even the atmosphere replacement type has a difficulty in purging, and a photocatalyst surface device is required.

(3) Clean Atmosphere Device As a clean atmosphere device, there are a device for supplying or circulating clean air and a clean gas, and a device for processing or processing in a clean atmosphere. A gas purification device, a clean chamber, and the like are also examples. The means for removing contaminant components using an adsorbent / absorbent makes it difficult to control the life of the adsorbent / absorbent, and requires a photocatalyst surface device to reliably maintain a permanent cleanliness.

[0118]

EXAMPLES Examples of the above-described embodiment will be described below.

(Example 1) The processing of the present invention was carried out in the processing and storing process of a metal precision part. The metal is a combination of stainless steel, brass, cast aluminum alloy, and the like, and the shape is often complicated, and screw holes for attachment are machined everywhere. Table 11 shows the processing results.

[0120]

[Table 11]

The deposited oil was 0.5 μg after the steam injection treatment.
/ Cm ² (about 7 molecular layers). After forming the photocatalyst surface by the photocatalyst steam injection treatment, the organic matter on the component surface after being stored in the near ultraviolet lamp insertion container for 24 hours was purified to a much smaller level than the monomolecular layer.

In the general cleaning treatment of the comparative example, the surface of the component was treated with 100 μg / atmospheric organic matter in addition to the remaining surfactant.
Contamination due to L to 1000 μg / L overlaps, resulting in an organic contaminated surface of several tens of molecular layers.

(Embodiment 2) Embodiment 2 shows an example of purification in an assembling process of a precision device in which metal precision parts are provided inside a metal chamber. Example 1 is a metal precision part.
In Table 7 above. Table 12 shows the results.

[0124]

[Table 12]

When the storage step, the assembling step, and the assembling apparatus were all subjected to photocatalytic treatment, the surface purification level (<1 × 10 ¹² molecules / cm ² ) of Example 1 could be completely maintained. It became clear.

From the comparative example, it can be seen that in a general assembly work in a clean room, an organic substance-contaminated surface having a high concentration of 5 digits or more is obtained.

Example 3 In Example 3, the surface of a clean room constituent material such as a clean room, a duct, a curtain, a wall, a floor, a ceiling, a work table, etc., was subjected to a photocatalyst water vapor injection treatment. Table 13 shows the results.

[0128]

[Table 13]

[0129] The total organic matter concentration in the clean room air was about two orders of magnitude cleaner than before this treatment. Although it is not possible to carry out spray cleaning of aqueous solutions containing various components on the surface of a clean room constituent material, there is no problem in spraying a photocatalyst steam containing no components other than titanium oxide fine particles at all. Since the spray surface is naturally dried by air circulation, no special drying treatment is required.

(Embodiment 4) Embodiment 4 shows an example of cleaning a wafer carrier box. Table 14 shows the results.

[0131]

[Table 14]

As shown in Table 14, in the photocatalyst steam injection carrier box, the concentration of organic substances on the wafer surface was reduced to a very small level as compared with the conventional product.

(Embodiment 5) In Embodiment 5, an example of purifying clean gloves will be described. Clean gloves are produced and packaged at a general clean level, so even if they are new, the organic matter concentration on the surface is high (Comparative Example). This clean glove was stored in the photocatalyst container shown in Example 1 for 24 hours. Table 15 shows the results.

[0134]

[Table 15]

As described above, the organic matter on the surface of the clean glove was purified to a level much smaller than that of the monomolecular layer. Here, the same favorable results as in Table 15 were obtained also when the photocatalytic water was sprayed and sprayed on the surface of the clean gloves by air pressure instead of storing the clean gloves in the photocatalyst container.

(Embodiment 6) In manufacturing a magnetic disk,
After the cleaning step, the disk substrate entering the magnetic alloy sputtering step was stored in the photocatalyst container shown in Example 1 for 24 hours. Table 16 shows the results.

[0137]

[Table 16]

The degree of surface cleaning was higher than that in a case where the magnetic disk was stored in a general clean level clean room, which contributed to the improvement of the performance of the magnetic disk.

(Embodiment 7) In Embodiment 7, an example of purification in an optical device will be described as an example of a photocatalyst surface device. An optical lens and a window plate for a semiconductor manufacturing stepper device were used as a photocatalytic surface, and a temporal decrease in light transmittance was measured in comparison with a case where no photocatalytic treatment was performed. Table 17 shows the results.

[0140]

[Table 17]

The optical lens and the window plate were preliminarily subjected to pure water vapor spray cleaning, and thereafter, photocatalytic water vapor spray was performed. Optical lenses and window plates without photocatalyst lose light transmittance due to the attachment of atmospheric organic matter with the passage of days, but it is clear that the light transmittance does not decrease when the surface is a photocatalyst. It became.

(Example 8) In Example 8, a change in light transmittance with time was measured in comparison with a case where a camera lens was used as a photocatalytic surface and no photocatalytic treatment was performed. A spray of photocatalytic water was sprayed on the surface of the camera lens by pneumatic atomization. The results were as favorable as in Table 17. It became clear that the light transmittance of the camera lens without spray treatment declined due to the attachment of atmospheric organic matter with the lapse of days, whereas the light transmittance did not decrease when the photocatalyst surface was used. .

Example 9 In Example 9, the surface of a show window glass was subjected to a photocatalyst steam spray treatment. The results are shown in Table 18. Thus, the number of times of surface cleaning was reduced. The cleaning with an aqueous solution containing an acid or an alkali cannot be performed due to the influence on the store and the product, but there is a convenience that the steam spray can be performed without any trouble.

[0144]

[Table 18]

(Embodiment 10) Embodiment 10 shows an example of purification applied to a car wash. The results are shown in FIG. In this way, the required frequency of car washing has been greatly reduced due to the effect of natural light purification on the photocatalytic surface.

[0146]

[Table 19]

(Example 11) [0147] In Example 11, after cleaning the kitchen wall surface with steam, the photocatalyst steam was sprayed. In addition to the normal illumination, a near-ultraviolet lamp (50 W
１００100 W). The results are shown in Table 20. In this way, the wall surface could always be kept in a clean state without touch of oil stains.

[0148]

[Table 20]

Example 12 In Example 12, the mist of photocatalytic water was sprayed on the display surface and keyboard of a personal computer by pneumatic atomization. By using a hand-held sprayer and spraying according to the frequency of use, dirt on the screen was reduced and the keyboard could be kept free of hand marks. The spraying of the aqueous solution cannot be performed on these surfaces, but the spraying of the mist can be performed without any trouble. In addition, since it dries quickly and has no harmful components, there is no need to consider the influence on the surroundings.

[0150]

According to the present invention, a photocatalyst surface is formed by spraying photocatalytic water at normal temperature or water vapor onto the surface of an object to be purified, and the surface is "clean-cleaned" to a molecular or atomic level. Can be. The present invention is applicable to an extremely wide range of purification targets, and various devices in a clean room,
Semiconductor devices, magnetic disk devices, optical devices, medical devices,
Not only various devices such as measuring devices, but also various vehicle surfaces, interiors of buildings and structures, surfaces of furniture and window boards, surfaces of display devices such as liquid crystal panels and television screens, personal computers, telephones,
It can be widely applied to the purification of office equipment, daily equipment and equipment surfaces.

In particular, when the photocatalytic water is sprayed at room temperature, the concentration of the photocatalyst water is extremely low and a small amount (in the form of a mist) as compared with the case where the photocatalyst water containing high-concentration solute fine particles is jetted onto the surface of the object to be washed. It is sufficient to use the photocatalyst water of (2), and it is possible to achieve sufficient purification while satisfying the recent demands for resource saving and environmental applicability.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a main configuration of a steam generator according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a main configuration of a photocatalyst container according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Evaporator 2 Evaporation heating block 3 Superheater 4 Superheating heating block 5 Constant flow pump 6 Pressure control needle valve 7 Pressure gauge 8 Thermometer 9 Thermometer 10 Valve for pure water 11 Valve for catalyst solution 12 Steam introduction valve 13 Steam Injection valve 14 Steam injection nozzle 15 Processing chamber 16 Processing surface 20 Parts storage container 21 Parts storage basket 22 Near ultraviolet lamp

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3B201 AA03 AB01 BB13 BB21 BB92 BB93 BC01 CB11 CC21

Claims (29)

[Claims] 1. A first step of injecting photocatalytic water vapor onto a surface of an object to be purified, and a second step of irradiating light containing ultraviolet light onto the surface of the object to be purified.
And a step of cleaning the surface. 2. The surface cleaning method according to claim 1, further comprising a third step of purifying the surface of the object to be purified by injecting water vapor before the first step. 3. The surface cleaning method according to claim 1, wherein the object to be purified is a material constituting a clean atmosphere, an apparatus operating in the clean atmosphere, a component, and a material thereof. . 4. The surface cleaning method according to claim 1, wherein the irradiation with the light including the ultraviolet rays is performed during storage, assembling, or operation of the object to be purified. . 5. After the second step, water vapor is injected onto the surface of the object to be purified to form a photocatalyst removal surface.
5. The method according to claim 2, further comprising the step of:
The surface cleaning method according to any one of the above items. 6. The ultraviolet light having a wavelength of 300 nm to 40 nm.
The surface cleaning method according to any one of claims 1 to 5, wherein the light is a light in a near ultraviolet region within a range of 0 nm. 7. The ultraviolet light having a wavelength of about 180 nm to 3 nm.
The surface cleaning method according to any one of claims 1 to 5, wherein the light is an ultraviolet ray within a range of 00 nm. 8. The photocatalyst steam is steam generated from a titanium oxide pure water dispersion, and the steam contains titanium oxide fine particles.
The method for cleaning a surface according to any one of claims 7 to 10. 9. The method according to claim 8, wherein the titanium oxide pure water dispersion contains titanium oxide having a hydrophilic surface having a particle diameter of 2 nm to 300 nm and contains no other components. Surface cleaning method. 10. An apparatus for irradiating a photocatalyst surface formed on a surface of an object to be purified with ultraviolet light, which irradiates light containing ultraviolet light, wherein the surface of the object to be purified is purified by the irradiation of the ultraviolet light. Surface cleaning device. 11. A steam injection means for purifying the surface of the object to be purified by steam injection, and a photocatalyst steam injection means for making the surface of the object to be purified the photocatalyst surface by photocatalytic steam injection. Surface cleaning equipment. 12. A steam injection means for purifying the surface of an object to be purified by steam injection, a photocatalyst steam injection means having a surface of the object to be purified by a photocatalyst steam injection, and an ultraviolet ray applied to the photocatalyst surface. And a UV irradiating means for irradiating the surface with ultraviolet light. 13. A first switching means for switching between steam injection and photocatalytic steam injection, and a second switching means for switching between saturated steam injection and superheated steam injection.
And a switching means for injecting the predetermined steam determined by the first and second switching means. 14. A photocatalyst container comprising a closed container provided with an ultraviolet lamp, wherein the surface of the object to be purified having the photocatalyst surface housed therein is irradiated with ultraviolet light. 15. A light purification surface of an object to be purified, characterized in that the surface purified by steam treatment is made into a photocatalyst surface by photocatalytic steam treatment, and the surface is irradiated with near ultraviolet rays. 16. The photo-purifying surface of an object to be purified according to claim 15, wherein the photo-catalyst surface is obtained by removing the photo-catalyst on the surface by steam treatment after irradiating the photo-catalyst surface with ultraviolet rays. 17. A photocatalyst water is sprayed on the treated surface in a mist state.
A method for forming a photocatalyst surface, comprising attaching fine particles in the photocatalyst water to the surface. 18. The photocatalytic water is a pure water dispersion in which the fine particles are titanium oxide.
8. The photocatalyst surface forming method according to 7. 19. The concentration of the fine particles of the photocatalytic water is:
The photocatalyst surface forming method according to claim 17 or 18, wherein the value is in the range of 0.01 g / L to 100 g / L. 20. A spraying device having a nozzle for spraying photocatalytic water in a mist form, wherein the photocatalytic water is sprayed from the nozzle onto a processing surface, and fine particles in the photocatalytic water are attached to the surface. Photocatalyst surface forming device. 21. The photocatalyst water is a pure water dispersion in which the fine particles are titanium oxide.
The photocatalyst surface forming apparatus according to 0. 22. The concentration of the fine particles in the photocatalytic water is:
22. The photocatalyst surface forming apparatus according to claim 20, wherein the value is in the range of 0.01 g / L to 100 g / L. 23. The photocatalyst surface forming apparatus according to claim 20, wherein the spraying unit sprays the photocatalyst water at normal temperature from the nozzle onto the processing surface by air pressure. 24. The photocatalyst surface forming apparatus according to claim 20, wherein the spraying unit sprays the photocatalytic water as steam from the nozzle onto the processing surface. 25. The spraying means includes a first steam spray mechanism for spraying steam of the photocatalytic water and a second steam spray mechanism for spraying pure water steam, the first steam spray mechanism being switchable. 25. The steam spray mechanism according to claim 24, wherein the steam is sprayed between the saturated steam and the superheated steam in a switchable manner.
4. The photocatalyst surface forming device according to item 1. 26. A photocatalytic surface device having a surface on which fine particles in the photocatalytic water adhere by spraying the photocatalytic water. 27. The photocatalyst surface device according to claim 26, wherein the photocatalyst surface device is used for manufacturing a semiconductor device and a liquid crystal device, and is a substrate transfer device for transferring a substrate. 28. The photocatalyst surface device according to claim 26, which is an optical device provided with an optical system. 29. The photocatalyst surface apparatus according to claim 26, wherein the apparatus is a clean atmosphere apparatus for cleaning a predetermined atmosphere.