JP2869241B2 - Particle detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fine particle detecting apparatus utilizing light scattering by fine particles, and more particularly, to a fine particle detecting apparatus having improved fine particle detecting sensitivity.

[0002]

2. Description of the Related Art As a conventional device of this type, for example, a device shown in FIG. 7 is known. As shown in FIG. 7, the fine particle detection device shown in FIG. 7 is disposed diagonally above a pair of plane mirrors 1 and 1 arranged in parallel with each other and one plane mirror 1 and directed toward the other plane mirror 1. A light source 2 for irradiating light rays,
An optical sensor (not shown) is provided for detecting light scattered by fine particles flowing between the plane mirrors 1 and 1 while the light beam 3 emitted from the light source 2 is repeatedly reflected by the plane mirrors 1 and 1. . The light rays are reflected between the two plane mirrors 1 and 1 many times to form a ray network in the space between the two plane mirrors 1 and 1 where fine particles are scattered.

Next, the operation will be described. When a light beam 3 is emitted from the light source 2, the light beam 3 is applied to each of the plane mirrors 1, 1
While the reflection is repeated between the two plane mirrors, light scattering is generated by the fine particles flowing between the two plane mirrors 1 and 1, and the scattered light is detected by an optical sensor to detect the fine particles. Then, the light beam that has been repeatedly reflected goes out from the lower end of the other plane mirror 1 to the outside.

[0004]

However, since the conventional particle detecting device is composed of two plane mirrors 1 and 1 whose reflecting surfaces for reflecting light rays are parallel to each other, the light rays are contained in each of the plane mirrors 1 and 1. As if making a net, each plane mirror 1,
It was necessary to set the parallelism of 1 strictly. In addition, during use of this detection device, one or both of the plane mirrors 1 are misaligned, and it is necessary to readjust the parallelism during operation, thereby causing a problem of significantly lowering the operation rate.

[0005] When the above-mentioned particle detecting device is installed, it is preferable that the light beam network is installed so as to be perpendicular to the flow of the particles so as to make the most effective use of the light beams. If installed, the position of the optical sensor that detects scattered light hinders the flow of fine particles, which is not preferable. Therefore, there is a problem that the fine particle detection device cannot be installed perpendicularly to the flow of fine particles. Furthermore, since these precipitate out on the plane mirror 1 in a gas atmosphere having a reactive deposition property, there is a problem that the above-described particle detection device cannot be installed in such an atmosphere.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. For example , there is no need to adjust the mirror surface during operation, and the detection sensitivity of fine particles can be increased by making full use of light rays. It is an object of the present invention to provide a fine particle detection device that can be used even in a reaction-precipitating gas atmosphere without erroneous counting.

[0007]

According to a first aspect of the present invention, there is provided a particle detecting apparatus, comprising: a mirror surface formed on a circumferential surface; and a light beam which is disposed outside the mirror surface and irradiates the mirror surface with an oblique direction. A light source and light rays from the light source are repeatedly reflected many times inside the mirror surface to form a ray network that can be regarded as a substantially flat surface, and by detecting the scattered light scattered from the fine particles passing through the mirror surface, the fine particles are detected. And an optical sensor for detecting Further, the particle detecting device according to claim 2 of the present invention comprises a mirror surface formed on the inner circumferential surface, a light source disposed on a side of the mirror surface and irradiating a light beam toward the mirror surface, and a light beam from the light source. While forming a ray network that can be regarded as a substantially plane by repeating reflection many times inside the mirror surface,
An optical sensor for detecting fine particles by detecting scattered light scattered from fine particles passing through the inside of the mirror surface; and a temperature control means for controlling the temperature of the mirror surface. Further, the fine particle detection device according to claim 3 of the present invention includes a support provided on a pipe through which a reactive deposition gas flows, a light source disposed outside the support and emitting light, and A light sensor for detecting the light beam of the above, the light source irradiates the light from the light source to the reactive deposition gas flowing through the support through the pipe, the fine particles in the reactive deposition gas by the optical sensor In the fine particle detection device, the support has an optical body in direct contact with the reactive deposition gas on the light path, and the optical body is temperature-controlled by temperature control means, and the reactive deposition gas is It is designed to prevent precipitation on the surface of the optical body.

[0008]

According to the present invention, when light is emitted from a light source,
Light rays are incident on a mirror surface formed on the circumferential surface and are reflected many times within the mirror surface without leaking to the outside to form a light ray network which can be regarded as a substantially flat surface. The fine particles hit the light beam network only once, generating scattered light, and the scattered light is detected by an optical sensor. Further, the temperature of the mirror surface can be adjusted by the temperature control means to prevent the reactive deposition gas from depositing on the mirror surface, thereby maintaining the initial detection sensitivity.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments shown in FIGS. In each of the drawings, FIG. 1 is a plan view showing one embodiment of the fine particle detecting device of the present invention, FIG. 2 is a cross-sectional view of the fine particle detecting device shown in FIG. 1, and FIG. FIG. 4 is a perspective view showing a state of detecting fine particles, FIG. 4 is a diagram corresponding to FIG. 2 showing another embodiment of the particle detecting device of the present invention, and FIG. 5 is a diagram corresponding to FIG. 1 showing still another embodiment of the particle detecting device of the present invention. FIG. 6 and FIG. 6 are views corresponding to FIG. 1 showing still another embodiment of the particle detecting apparatus of the present invention.

As shown in FIGS. 1 and 2, a fine particle detecting device D of this embodiment has a mirror surface 11 which is an example of an optical body formed on a circumferential inner surface formed on a support 10 and a mirror surface 11 of the mirror surface 11. A light source 12 disposed laterally and irradiating a light beam 13 toward the mirror surface 11, and a light beam 13 from the light source 12
An optical sensor for detecting fine particles by detecting scattered light scattered from the fine particles passing through the inside of the mirror surface while the reflection is repeated many times inside the mirror surface; and controlling the temperature of the mirror surface. Temperature control means (not shown).

FIG. 3 shows the particle detecting device D more specifically. According to FIG.
Is formed in a ring shape, and a mirror surface 11 which is an optical body is formed on an inner peripheral surface of the ring-shaped support body 10. Further, a light source 12 for irradiating a light beam 13 in a substantially radial direction is attached to a mirror surface 11 of the ring-shaped support 10,
The light source 13 emits a light beam 13 from the hole 11A of the mirror surface 11 to the mirror surface 11 opposite thereto. The light source 12 is arranged such that the light beam 13 enters at a position slightly deviated from the center of the mirror surface 11, and the light beam 13 is repeatedly reflected many times as shown in FIG. Is formed to increase the detection sensitivity of the fine particles passing through the mirror surface 11.

An optical sensor 14 is provided outside the support 10 along the axis thereof in the direction of the axis of the support, and scatters light scattered from the fine particles based on the light 13 from the light source 12. By detecting, the fine particles passing through the mirror surface 11 are detected. Further, the fine particle detecting device D is provided with a temperature control means (not shown) for controlling the surface of the mirror surface 11 to a temperature at which no reactive deposition gas is deposited. Gas is prevented from being deposited on the surface of the mirror surface 11.

Next, the operation will be described. If the fine particle detecting device D is arranged in the passage 20 of the gas pipe containing the fine particles as shown in FIG. 3, the gas flows through the passage 20 and passes through the mirror surface 11 of the support 10. Pass through the area enclosed by. At this time, while the light beam 13 emitted from the light source 12 toward the mirror surface 11 is repeatedly reflected on the surface of the mirror surface 11, a light network which can be regarded as a high-density substantially flat surface near the center of the mirror surface 11 is skewed with respect to the airflow direction. The fine particles can be detected with high sensitivity, particularly at this central portion.

Therefore, according to this embodiment, when the velocity of the gas is high at the center of the passage 20, the fine particles contained in that part can be detected with high sensitivity, and the optical sensor 1 can be detected.
4 can be arranged at a position that does not hinder the flow of gas. Further, according to the present embodiment, the mirror surface 11 is a circumferential mirror surface surrounding the air flow, so that it is not necessary to adjust the parallelism of the mirror surface 11 as in the prior art. Even in a neutral gas atmosphere, the initial reflection performance is maintained without depositing the reactive deposition gas on the mirror surface 11, and as a result, the fine particle detection device D can be maintenance-free.

FIG. 4 is a view showing another embodiment of the present invention. In the particle detecting apparatus D of this embodiment, a light source 12 is provided outside a support 10 and a light beam 13 is emitted outside a mirror surface 11. The light beam 13 is applied to the mirror surface 11 facing the light source 12 from an oblique direction. With the arrangement of the light source 12, the mirror surface 11 is formed so that its cross section is curved outward so that the incident light beam 13 is effectively reflected in the mirror surface 11 and the light beam 13 is repeated many times in the mirror surface 11. . Therefore, according to the present embodiment, since the light source 12 is located outside the mirror surface 11, it is not necessary to provide the hole 11A through which the light source 12 passes as in the above-described embodiment. Without disturbing the reflection of light, the light beam 13 can be used more effectively, and fine particles in the airflow can be detected with higher sensitivity.

FIG. 5 is a view showing still another embodiment of the present invention. In a fine particle detecting apparatus D of this embodiment, a light source 12 is provided with a hole 11A in a mirror surface 11 similarly to that shown in FIG. A light beam 13 is made to enter from the hole 11A at a position greatly deviated from the center of the mirror surface 11, so that the light beam 13 forms a light network near the surface of the mirror surface 11 as shown in FIG. Therefore, according to the present embodiment, particularly when used in a semiconductor manufacturing apparatus, if the diameter of the mirror surface 11 is adjusted to the diameter of the wafer, the fine particles can be detected intensively at the peripheral portion of the wafer. .

FIG. 6 is a view showing still another embodiment of the present invention. The particle detecting apparatus D of this embodiment is configured by combining the light source 12 shown in FIG. 1 and the light source 12 shown in FIG. With such a configuration, fine particles can be detected at the center of the airflow and at the periphery of the airflow.

[0018]

As described above, according to the particle detecting device of the first aspect of the present invention, it is not necessary to readjust the mirror surface during operation, without counting one particle more than once. The detection sensitivity of fine particles can be enhanced by making the best use of the light beam. In addition, there is no need to form a through hole for allowing light from the light source to pass through the mirror surface, and therefore, there is no inconvenience that light rays hit the edge of the through hole and the reflection of light rays is disturbed. Instead, the number of reflections of light rays can be set more, a dense light ray network can be formed, and fine particles in the airflow can be detected with higher sensitivity. ◎ Further, according to the fine particle detecting device according to the second aspect of the present invention, it is not necessary to readjust the mirror surface during operation, and it is possible to maximize the detection sensitivity of the fine particles by utilizing the light rays and to increase the reaction. It can be used even in a deposition gas atmosphere. Further, according to the fine particle detecting device according to the third aspect of the present invention, even in a reactive deposition gas atmosphere, it can be used in a state where the performance is maintained without depositing the reactive deposition gas on the surface of the optical body. .

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of a particle detection device according to the present invention.

FIG. 2 is a cross-sectional view of the particle detection device shown in FIG.

FIG. 3 is a partially cutaway perspective view showing a state of detecting fine particles of the fine particle detection device shown in FIG. 1;

FIG. 4 is a diagram corresponding to FIG. 2 showing another embodiment of the fine particle detection device of the present invention.

FIG. 5 is a view corresponding to FIG. 1 showing still another embodiment of the fine particle detection device of the present invention.

FIG. 6 is a view corresponding to FIG. 1, showing still another embodiment of the fine particle detection device of the present invention.

FIG. 7 is a plan view showing an example of a conventional particle detection device.

[Explanation of symbols]

11 mirror surface, 12 light sources, 13 light beams, 14 optical sensors.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01N 15/00-15/14 G01N 21/00 G01N 21/01 G01N 21/17-21/61

Claims (3)

(57) [Claims] 1. A mirror surface formed on a circumferential surface and an outer surface of the mirror surface.
A light source for irradiating a light beam from an oblique direction arranged by and this mirror surface, while the light beam from the light source to form a light beam network which can be regarded as generally plane repeated multiple times reflected within the mirror, the mirror inside A fine particle detection device comprising: an optical sensor that detects fine particles by detecting scattered light scattered from passing fine particles. 2. A mirror surface formed on a circumferential surface, a light source disposed on a side of the mirror surface and irradiating a light beam toward the mirror surface, and a light beam from the light source is reflected many times inside the mirror surface. An optical sensor for detecting fine particles by detecting scattered light scattered from fine particles passing through the mirror surface while forming a ray network that can be regarded as a substantially flat surface repeatedly,
And a temperature control means for controlling the temperature of the mirror surface. 3. A support provided on a pipe through which a reaction-precipitating gas flows, a light source provided outside the support for irradiating a light beam, and an optical sensor for detecting a light beam from the light source. the anti flowing through said support through the pipe
In a fine particle detection device for irradiating a light beam from the light source to the depositable gas and detecting the fine particles in the gas by the optical sensor, the support may include the reaction on a light beam path.
Has an optical member in direct contact with the deposition gas, the optical body is temperature controlled by a temperature control means, said reactive deposition gases
To prevent precipitation on the surface of the optical body
Particle detector device are.