JPH0822393B2 - Particle charging / collecting unit device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning device and method for cleaning a space, and more particularly to a charging / collecting unit device for charging / collecting fine particles existing in a space by using photoelectrons. The charge / collection method used. Charge of the present invention
The collection unit device and the method using the same can be used in the field of charging and collecting (removing) fine particles to obtain a clean gas or a clean space. For example, clean rooms in various industries such as homes, offices, hospitals, semiconductor industry, pharmaceutical industry, food industry, agriculture and forestry industry, pharmaceuticals, precision machinery industry, aseptic rooms, safety cabinets, clean boxes, storage of valuables. It is a clean closed space (in the presence of various gases or in a vacuum) in a storage, a wafer storage, a sealed transfer space for valuables, etc., cleaning of various CVD devices, and spaces related to various film forming devices.

[0002]

2. Description of the Related Art Many proposals have been made by the present inventor for charging and collecting fine particles by photoelectrons generated by irradiating a photoelectron emitting material with ultraviolet rays. Among the things that the present inventor has proposed in relation to space purification, the following are particularly relevant to the present invention. (1) Us patent 4,750,917
No.), (2) JP-A-63-77557, (3) JP-A-63-100955, (4) JP-A-2-10.
No. 034, (5) Japanese Patent Application No. 2-295422.
(6) Japanese Patent Application No. 3-22685. Further, regarding the charging conditions, there are (1) JP-A-2-8639.
(2) Japanese Patent Application No. 1-120563. In addition, the proposals relating to photoelectron emitting materials include (1) Japanese Patent Application Laid-Open No. 2-8638 and (2) Japanese Patent Application No. 1-155857.
No. 1, (3) Japanese Patent Application No. 1-153335, (4) Japanese Patent Application No. 2
No. 278123 and (5) Japanese Patent Application No. 2-295423.

[0003]

In the above-mentioned conventional charging / collecting of fine particles by photoelectrons, an ultraviolet source, a photoelectron emitting material, and an electrode are individually installed and used. That is, an ultraviolet source,
Since the photoemissive material and the electrodes were installed separately, there was room for improvement depending on the field of application. Further, in the design of the cleaning device, if the ultraviolet source, the photoelectron emitting material, and the electrode are integrated, the handling becomes easy and the cleaning becomes compact, which is practically advantageous.

The above problem will be described below with reference to examples. FIG. 4 is a configuration diagram showing an operation of removing fine particles in a wafer storage in the semiconductor industry. The wafer storage 1 includes an ultraviolet lamp 2, a photoelectron emitting material 3, an electric field setting electrode material 4,
It is composed of a reflecting surface 5 for the ultraviolet rays from the ultraviolet lamp 2. The particles 6 in the wafer storage 1 are UV lamps 2.
Photoelectrons 7 emitted from the photoelectron emission material 3 irradiated with
And become charged fine particles 8. The charged fine particles 8
Are collected by the electric field setting electrode material 4. Here, since the wafer storage 1 is a closed space, the electric field setting electrode material 4 serves as a collector for the charged fine particles. Reference numeral 9 indicates a wafer carrier, and 10 indicates a wafer. The photoelectron emitting material here has already been proposed by the present inventor (Japanese Patent Application No. 29542/1990).
No. 3) A substance that emits photoelectrons is added to the surface of an ultraviolet-transparent substance in the form of a thin film. In FIG. 4, 50ÅAu is added to the surface of a glass material.

In such a case, since the ultraviolet lamp, the photoelectron emitting material, and the electrode material are individually installed, the ultraviolet lamp 2 is installed outside the wafer storage 1, so that the emitted ultraviolet light is effectively emitted. 3 is not irradiated (for example, with respect to the photoelectron emitting material 3, ultraviolet rays in the direction of the reflecting surface have a large loss). In addition, since the electric field (electric field) is set between the photoelectron emitting material 3 and the electrode material 4, (a) the wafer is placed in the electric field, and depending on the state of the wafer (eg, the surface is activated, If there is) it may be affected by the action of the electric field. Further, (b) since the distance between the photoelectron emitting material 3 and the electrode material 4 is long, there is a problem that the applied voltage for setting the electric field becomes high, and there is room for improvement. Therefore, the present invention solves the above-mentioned problems, and a particle charging / collecting unit device capable of effectively charging / collecting particles and a method of charging / collecting particles using the charging / collecting unit. The purpose is to provide.

[0006]

In order to solve the above-mentioned object, in the present invention, the charge / charge of fine particles in space by photoelectrons is performed.
In the collection unit device, an ultraviolet source, a photoelectron emitting material, and an electrode are used , and the ultraviolet source is a rod-shaped ultraviolet lamp.
According to another aspect of the present invention, there is provided a fine particle charging / collecting unit device in which the lamp is surrounded by a cylindrical photoelectron emitting material and a wire mesh electrode to be integrated into a unit. Further, the present invention provides a method of charging / collecting fine particles in a space, characterized in that the charging / collecting unit is installed in a space in which fine particles are present. In the above integration,
The UV source is surrounded by a photoelectron emitting material, and an electrode (for an electric field) is installed in the vicinity of the ultraviolet light source, and at least one of the shape of the photoelectron emitting material and the electrode is discharged from the photoelectron emitting portion by the fine particles present in the cleaning space. The photoelectron emitting portion can be moved to the photoelectron emitting portion so as to be charged by the generated photoelectrons.

An example of a charge / collection unit of particles in space by photoelectrons according to the present invention is shown in FIGS. 1 and 2. In FIG. 1, the particle charging / collecting unit of the present invention comprises an ultraviolet lamp (rod) 11 as an ultraviolet source, a photoelectron emitting material 13 on a glass base material 12 in a shape surrounding the lamp (cylindrical), and the photoelectron emitting material. The wire mesh electrode 14 has a shape (cylindrical shape) surrounding the material 13. The photoelectron emission material 13 is added in a thin film form on the surface of the quartz glass 12 which is an ultraviolet ray transmitting substance, and emits photoelectrons 15 radially in the circumferential direction by irradiation of ultraviolet rays from the ultraviolet ray lamp 11. As will be described later, the emission of the photoelectrons is effective by irradiation with ultraviolet rays in an electric field, so that an electric field is formed between the photoelectron emitting material 13 (− pole) and the electrode 14 (+ pole) (photoelectron emitting portion). .

The electrode 14 serves not only for forming an electric field as described above, but also as a collector for charged fine particles. That is, the photoelectrons 15 emitted from the photoelectron emitting portion charge the fine particles floating in the vicinity as described later, and become charged fine particles, which are collected by the electrode 14 and the nearby space is cleaned. FIG. 2 shows another shape of the charging / collecting unit. The charging / collecting unit shown in FIG. 2 includes an ultraviolet lamp (bar-shaped) 21 and a wire mesh electrode 2 surrounding the lamp (cylindrical).
2. The wire mesh photoelectron emitting material 23 has a shape (cylindrical shape) surrounding the wire mesh electrode 22. An electric field is formed between the photoelectron emitting material 23 and the electrode 22, and photoelectrons 24 are emitted by irradiating the photoelectron emitting material 23 with ultraviolet rays.

Next, the respective constitutions of the present invention will be explained in detail. The photoelectron emitting material may be any material as long as it emits photoelectrons upon irradiation with ultraviolet light, and a material having a smaller photoelectric work function is more preferable.
r, Ca, Y, Gd, La, Ce, Nd, Th, Pr,
Be, Zr, Fe, Ni, Zn, Cu, Ag, Pt, C
d, Pb, Al, C, Mg, Au, In, Bi, Nb,
Any one of Si, Ta, Ti, U, B, Eu, Sn, P, W or a compound or alloy thereof is preferable, and these are used alone or in combination of two or more kinds. As the composite material, a physical composite material such as amalgam can also be used. For example, compounds include oxides, borides, and carbides, and oxides include BaO, SrO, CaO, Y ₂ O ₅ , and G.
d ₂ O ₃ , Nd ₂ O ₃ , ThO ₂ , ZrO ₂ , Fe ₂ O
₃ , ZnO, CuO, Ag ₂ O, La ₂ O ₃ , PtO,
PbO, Al ₂ O ₃ , MgO, In ₂ O ₃ , BiO, N
bO, BeO, etc., and boride contains YB ₆ , C
dB ₆ , LaB ₅ , NdB ₆ , CeB ₆ , EuB ₆ , P
rB ₆ , ZrB _{2 and the} like, and further U as a carbide
C, ZrC, TaC, TiC, NbC, WC and the like.

As the alloy, brass, bronze, phosphor bronze, an alloy of Ag and Mg (Mg is 2 to 20 wt%), C
An alloy of u and Be (1 to 10 wt% of Be) and an alloy of Ba and Al can be used, and the alloy of Ag and Mg, the alloy of Cu and Be, and the alloy of Ba and Al are preferable. . Oxide heats only the metal surface in air,
Alternatively, it can be obtained by oxidizing with a chemical. As another method, it is also possible to heat before use to form an oxide layer on the surface to obtain a stable oxide layer for a long period of time. As an example of this, an alloy of Mg and Ag can form an oxide film on its surface in water vapor at a temperature of 300 to 400 ° C., and this oxide thin film is stable for a long period of time.

Further, a substance that emits photoelectrons can be used by adding it to another substance. An example of this is an ultraviolet-transparent substance to which a substance capable of emitting photoelectrons is added. In the example of FIG. 1, Au is added in a thin film form as a substance capable of emitting photoelectrons on quartz glass as an ultraviolet ray transmissive substance (base material) (Japanese Patent Application No. 2-295423).
issue). In the example of FIG. 2, Au is added in the form of a thin film to the wire mesh Cu—Zn. The shape and structure of the photoelectron emitting material differ depending on the shape and structure of the device (unit), desired effect, and the like, as described later, and can be appropriately determined. The irradiation source for photoelectron emission from the photoelectron emitting material is
Irradiation may be any one as long as it emits photoelectrons by, but effective, in terms of operability, UV is generally preferred.

Any kind of ultraviolet light may be used as long as the photoelectron emitting material can emit photoelectrons by its irradiation.
Depending on the field of application, those having a sterilizing action are also preferable. The type of UV light depends on the application field, work content,
It can be appropriately determined depending on the use, economy and the like. For example, in the biological field, it is preferable to use deep ultraviolet rays together from the viewpoint of bactericidal action and efficiency. As the ultraviolet ray source, any one can be used as long as it emits ultraviolet rays,
It can be appropriately selected and used depending on the application field, the shape of the device, the structure, the effect, the economical efficiency and the like. For example, a mercury lamp, a hydrogen discharge tube, a xenon discharge tube, a Lyman discharge tube, or the like can be used as appropriate. In the biological field, sterilization wavelength 2
It is preferable to use an ultraviolet ray having a wavelength of 54 nm because the sterilizing effect can be used together.

Next, the positions and shapes of the ultraviolet ray source, the photoelectron emitting material, and the electrodes, which are the features of the present invention, will be described. These are characterized in that they are installed around an ultraviolet source and integrated as a charging / collecting unit (unit) for fine particles.
The position and shape of the photoelectron emitting material may be any as long as they can be installed so as to surround the ultraviolet rays emitted from the ultraviolet ray source (to increase the irradiation area). Normally, the ultraviolet rays from the ultraviolet source are radially emitted in the circumferential direction, and thus any material that can be installed in the circumferential direction so as to surround the ultraviolet rays may be used.

Next, any position and shape of the electrode can be used as long as an electric field can be formed between the electrode and the photoelectron emitting material. The electrode material and its structure may be those used in known charging devices. Any electrode material can be used as long as it is a conductor, and an example thereof is a tungsten wire mesh . This is installed so that an electric field can be formed near the photoelectron emitting material. The position of the photoelectron emitting material relative to the position of the electrode is near the ultraviolet lamp as shown in FIG.
As described above, it can be determined depending on the type and shape of the photoelectron emitting material, the field of use, the shape of the device, the scale, the effect, the economic efficiency, etc., on the opposite side (processing space side) of the ultraviolet lamp.

The type of photoelectron emitting material is a plate-shaped material, a pleat-shaped material, a wire mesh-shaped material (Japanese Patent Application Laid-Open No. 61-178050) as already proposed by the present inventor, and a protective film on the base material. With the addition of (Japanese Patent Application No. 1-155857),
A thin film (Japanese Patent Application No. 2-278123) and an ultraviolet-transparent substance (Japanese Patent Application No. 2-295423)
No.) can be used in an appropriate combination with the above electrode material for electric field. Among these, the kind of photoelectron emitting material suitable for the present invention is generally one in which at least one part is a wire mesh (Japanese Patent Laid-Open No. 61-17).
8050), an ultraviolet-transparent substance such as a glass material on which a substance capable of emitting photoelectrons is added in a thin film (Japanese Patent Application No. 2-295423), and one or more kinds of plate or curved surface. It is installed in the photoelectron emission unit in an appropriate combination. The combination of the photoelectron emitting material and the electrode material can be appropriately determined depending on the field of use, the scale of the device, the shape, the structure, etc. When installed in the space part, the fine particles present in the cleaning space part to be described later become Anything can be used as long as it can move quickly.

That is, as for the shape of the photoelectron emitting material or the electrode, one of them is present in the cleaning space so that the fine particles existing in the cleaning space are charged by the photoelectrons emitted from the photoelectron emitting part. Any particles may be used as long as the particles can move quickly to the photoelectron emitting portion. Such shapes are usually wire mesh, linear, rod-shaped, lattice-shaped, plate-shaped, pleated, curved, and the like, and these can be used alone or in combination of two or more kinds. Of these, it is preferable to use a wire mesh, rod, wire, plate, or lattice in a tubular shape for the above purpose.

The positions and shapes of the photoelectron emitting material and the electrodes surround the ultraviolet ray source, and the ultraviolet ray source, the photoelectron emitting material and the electrode can be integrated so that the ultraviolet ray emitted from the ultraviolet ray source can be effectively utilized and the photoelectron emission and the In order to effectively charge the fine particles by photoelectrons, it can be determined by a preliminary test or the like in consideration of the field of use, device scale, shape, effect, economical efficiency, and the like. For example, when using a rod-shaped (cylindrical) ultraviolet lamp, ultraviolet rays are emitted radially in the circumferential direction. Therefore, the more the radial radiation in the circumferential direction is applied to the photoelectron emitting material, the more the amount of photoelectron emission is increased. Will increase.

Therefore, in the example of FIG. 1, the ultraviolet lamp 1
First, 1 was surrounded by a cylindrical quartz glass (base material) 12 having a diameter larger than that of the ultraviolet lamp 11, and thin film Au was added as a photoelectron emitting material 13 to the surface of the quartz glass. Furthermore, a cylindrical metal net 14 having a larger diameter is surrounded by the electrode as an electrode, and the ultraviolet lamp 11, the photoelectron emitting material 13,
The electrode 14 is integrated. In the example of FIG. 2, the ultraviolet lamp 21 is first surrounded by a cylindrical wire mesh electrode 22, and a cylindrical wire mesh 23 is surrounded by the electrode 22, and is used as an electron emitting material to integrate them. The wire-mesh photoelectron emitting material 23 here is a thin film of Cu-Zn with Au added thereto.

Both the cylindrical electrode 14 in FIG. 1 and the cylindrical photoelectron emitting material 23 in FIG. 2 are in the shape of a wire mesh, so that the fine particles in the cleaning space can be easily (diffused) in the photoelectron emitting portion. You can move. Further, 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 and structure of the charged portion, the field of application, the expected effect (accuracy), and the like. The strength of the electric field can be appropriately determined depending on the coexisting water concentration, the type of the photoelectron emitting material, etc., and there is another invention of the present inventor in this regard.
The strength of the electric field is generally 0.1 V / cm to 2 KV / cm.

The distance between the photoelectron emitting material and the electrode may be such that an electric field can be formed between them and the photoelectrons from the photoelectron emitting material can charge the fine particles by the irradiation of the photoelectron emitting material with ultraviolet rays. It is preferable because the applied voltage can be low. It is generally within 20 cm, preferably within 5 cm, but can be appropriately determined depending on the scale of the apparatus, shape, field of use, and the like.

[0021]

Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited thereto. Example 1 Air cleaning in a wafer storage (FIG. 3) of a semiconductor factory was performed by charging fine particles in the basic configuration diagram of the present invention shown in FIG.
A case where the collection unit is used will be described with reference to FIGS. 1 and 3. The air cleaning of the wafer storage, which is the closed space (space in which gas does not flow and can be regarded as a stationary state) in FIG. 3, is performed by the ultraviolet lamp 11 installed inside the wafer storage and the shape surrounding the lamp (cylindrical shape). 1 is composed of a photoelectron emission material 13 on the glass base material 12 and a wire mesh electrode 14 having a shape (cylindrical shape) surrounding the photoelectron emission material 13 and is carried out by the fine particle charging / collecting unit B in FIG.

That is, the fine particles (fine particle substances) 16 in the wafer storage are charged by the photoelectrons 15 emitted from the photoelectron emitting material 13 irradiated with the ultraviolet lamp 11 in FIG. 1 to become charged fine particles, and the charged fine particles are The charged fine particles are collected by the collector 14, and the cleaning space (A) where the wafer exists is highly cleaned. B is the charge of fine particles in the space
The collecting unit is composed of the fine particle charging / collecting unit shown in FIG. 1 which emits photoelectrons from the photoelectron emitting unit to charge the fine particles and collect (remove) them. Photoelectron emission material 13 here
Is a thin film of 50ÅAu added to the surface of the glass material. In this way, the fine particles (particulate matter) in the wafer storage are collected and removed, and the wafer storage becomes clean air.

The electrode 14 is installed in order to perform photoelectron emission from the photoelectron emission material 13 in an electric field. That is, an electric field is formed between the photoelectron emitting material 13 and the electrode 14 (photoelectron emitting portion). The particles are efficiently charged by the photoelectrons 15 generated by irradiating the photoelectron emitting material 13 with ultraviolet rays in an electric field. The voltage of the electric field here is 50 V / cm. Also, the collection of charged fine particles is
This is performed using the electrode 14. The electrode material is a wire mesh Cu-
The Zn material is used after being plated with gold, and is installed at a position 1 cm from the photoelectron emitting material. Reference numerals 9 and 10 denote a wafer carrier and a wafer, respectively. In this example, 1 in the wafer storage
It is preferable to stir an air stream in the part because the removal rate of fine particles becomes faster. Examples of the method include heating and making a temperature difference, mechanical stirring, and the like, which can be appropriately used.

Example 2 The particle charging / collecting unit shown in FIG. 1 was installed in the wafer storage (cleaner) shown in FIG. Collection was performed, and the residual rate of fine particles was examined using a particle measuring device (particle counter). Purifier size: 10 liters Ultraviolet source: Sterilizing lamp (rod), 6W Photoelectron emitting material: Cylindrical quartz glass surface, thin film Au
(50Å) added. Electrode material: Cylindrical wire mesh (Cu-Zn plated with Au) having a diameter 2 cm longer than that of the photoelectron emitting material. Collection material for charged fine particles: Also used as an electrode material. Electric field voltage: 50V / cm

Particle charging / collecting unit: As shown in FIG. 1, an ultraviolet lamp (sterilization lamp) is surrounded by a cylindrical photoelectron emitting material, and the surrounding area is surrounded by a cylindrical wire mesh electrode. Sample gas (inlet gas): as shown in Table 1

[Table 1]

Results A fine particle concentration of 0.1 μm or more was measured with a measuring instrument. Table 2 shows the results.

[Table 2] As a blank, when the particle concentration in the purifier after leaving for 30 minutes in the case of no ultraviolet irradiation and no voltage application was examined, 90% of the initial concentration (inlet concentration) was recognized (measured).

In the first embodiment, one charging / collecting unit for fine particles is installed in the cleaning space, but a plurality of charging / collecting units may be installed depending on the application field, the scale of the apparatus, the shape, the effect, and the like. Needless to say. Further, in the above-mentioned example, the case where the photoelectron emitting material is installed at the position surrounding the ultraviolet source is shown, but the photoelectron in which the thin film photoelectron emitting material is added to the surface of the ultraviolet source (ultraviolet lamp) already proposed by the present inventor is shown. A discharging device (Japanese Patent Application No. 3-22685) can be used as well. When this photoelectron emission device is used, the above-mentioned electrodes may be installed around the photoelectron emission device and integrated.

[0028]

According to the present invention, the ultraviolet ray source is surrounded by the photoelectron emitting material and the electrode and integrated, whereby a compact fine particle charging / collecting unit device is obtained. In the integration, the ultraviolet light source was surrounded by the photoelectron emitting material, so that the ultraviolet light emitted from the ultraviolet light source could be effectively used without loss. For example, by arranging the photoelectron emitting material so as to surround the emitted ultraviolet rays in a radial direction in the circumferential direction, the photoelectron emitting material can be irradiated with the ultraviolet rays emitted in all directions. In the integration, since the electrode was placed near the photoelectron emission material and the distance between the photoelectron emission material and the electrode became close, the applied voltage for the electric field became low. Since the electric field is a small space between the photoelectron emitting material and the electrode, the influence of the electric field on the cleaning space can be ignored.

Since the ultraviolet rays emitted in all directions are effectively used, the number of lamps used can be considerably reduced when the ultraviolet lamp is used as the ultraviolet source as compared with the conventional method. This reduced the power used. Also, the performance as a charge / collector of fine particles has been improved. Since it can be installed anywhere in the space, the cleaning ability is improved. In the conventional method, the device structure as a cleaning device is limited, but if the charging / collecting unit is used, it is not limited. That is, the degree of freedom in designing the cleaning device has increased. In the purifier, if you want to improve the cleaning capacity (cleaning speed) from the initial design value, it is difficult with the conventional method, but with this method, the charging / collecting unit can be installed at any location, so the cleaning capacity Can be easily improved. The field of application has expanded and practicality has improved.

[Brief description of drawings]

FIG. 1A is a schematic configuration diagram showing a fine particle charging / collecting unit device of the present invention, and FIG. 1B is a sectional view thereof.

FIG. 2 is a schematic configuration diagram showing another particle charging / collecting unit device of the present invention.

FIG. 3 is a basic configuration diagram in which the unit of the present invention is used for air cleaning of a wafer storage.

FIG. 4 is a basic configuration diagram of a known air cleaning apparatus for a wafer storage.

[Explanation of symbols]

2, 11, 21: ultraviolet lamp, 3, 13, 23: photoelectron emitting material, 4, 14, 22: electrode, 7, 15, 24: photoelectron, 6, 16: fine particles, 9: wafer carrier, 1
0: Wafer, 12: Quartz glass

Claims (2)

[Claims] 1. A unit for charging and collecting particles in a space by photoelectrons, comprising an ultraviolet source, a photoelectron emitting material and an electrode, wherein the ultraviolet source is a rod-shaped ultraviolet lamp, and the lamp emits a cylindrical photoelectron. A unit for charging and collecting fine particles, which is characterized by being surrounded by a material and a wire mesh electrode and integrated into a unit. 2. The photoelectron emission material is added on a glass base material of an ultraviolet-transparent material, or has a wire mesh shape, and is arranged inside or outside the wire mesh electrode. 1. A unit for charging and collecting fine particles according to 1.