JPH07218419A - Light scattering type instrument and method for measuring particles in wide area - Google Patents

Abstract

PURPOSE:To provide an instrument and method for measuring particles by which particles or fine particles moving at high speeds can be measured with accuracy over a wide area. CONSTITUTION:A two-dimensional detector 8 having a light accumulating effect for irradiating particles 11 with a sheet-like light beam 6, the thickness of which is controlled in accordance with the moving speed of the particles 11, and detecting scattered light from the particles 11 arranged in a direction perpendicular to the sheet surface of the light beam 6. A picture processor 15 performs a specific integrating process on optical data detected by the detector 8 and the measuring area of the detector 8 is controlled by an objective lens having a zooming mechanism.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a particle measuring device for measuring particles in a vacuum, a gas, a liquid or a substrate surface over a wide area and a particle measuring method using the same.

[0002]

2. Description of the Related Art FIG. 12 shows, for example, JP-A-61-2742.
It is a figure which shows the flow visualization apparatus which is the conventional particle measuring apparatus published by the 38th publication. In the figure, 1 is a laser oscillator, 11 is a particle, 13 is a moving direction of the particle, 18 is a camera, 19 is a polyhedral reflecting mirror, 20 is a motor, 21 is a rod lens, and 22 is a nozzle which emits the particle 11 to be visualized.

Next, the operation will be described. The laser beam emitted from the laser oscillator 1 is scanned in the camera direction by a polyhedral reflecting mirror 19 equipped with a motor 20, and the beam is shaped into a sheet by a rod lens 21. This sheet-shaped beam irradiates the particles 11 emitted from the nozzle 22, and the scattered light is emitted from the camera 1.
The three-dimensional flow can be visualized by image-processing the two-dimensional image obtained by observing No. 8.

FIG. 13 shows, for example, Japanese Unexamined Patent Publication No. 5-172731.
It is a figure which shows the conventional particle detection apparatus published by the publication. In the figure, 11 is a particle, 13 is the moving direction of the particle,
Reference numeral 23 is a light source for generating the sheet-shaped light beam 6, 24 is a half mirror, 25 is a galvanometer, 26 is a transparent cell, and 27 is a transparent cell.
Is a detection unit in which a two-dimensional CCD is arranged, and 28 is a processing unit.

Next, the operation will be described. The particles 11 are flowing in the transparent cell 26, and the light emitted from the light source 23 is branched into two directions by the half mirror 24 and is made into the sheet-like light beam 6 by the galvanometer 25. The two light rays are irradiated to the inside of the transparent cell 26 at the angles of θ1 and θ2 from the horizontal plane, and the scattered light of the particles passing through the irradiation area reaches the detection unit 27. By irradiating light rays from two directions, particles that overlap in one sheet-like light ray area and are easily counted are irradiated by the other light rays, and inspection omission is prevented. Further, by this, the number of particles and the shape are obtained by the processing unit from the data obtained by the detector.

FIG. 14 shows, for example, Japanese Patent Application Laid-Open No. 2-287242.
It is a figure which shows the conventional particle detection apparatus published by the publication. In the figure, 16 is a wafer, 23 is a light source, 28 is a processing unit for data obtained from a photodetector 30, 29 is an objective lens, and 31 is a sample stage equipped with a drive mechanism.

Next, the operation will be described. Sample table 31
The wafer 16 installed on the wafer can be freely moved in the xy directions, and light is emitted from the light source 23 onto the wafer 16. If adhered particles are present on the wafer 16 in this irradiation region, the scattered light from these particles causes the objective lens 29 to move.
To reach the photodetector 30. This signal is processed by the processing unit 2
8 is added to record the position of particles and the like.

[0008]

Since the conventional flow visualization device for particle measurement is constructed as described above, in order to improve the data precision in three dimensions, the data obtained in two dimensions must be obtained. It is necessary to improve the accuracy of. However, when measuring high-speed particles having a high moving speed, it is necessary to scan the sheet-like laser beam at a higher speed than the moving speed of the particles. This is not only difficult to control the scanning to make the laser follow the movement of the particle, but even if the laser scanning can follow the movement of the particle, the irradiation time of the laser beam on the particle is shortened, and the particle The amount of scattered light is reduced. Therefore, the accuracy of the two-dimensional measurement is low, and it is actually difficult to visualize such high-speed particles. In addition, when visualizing the flow, fine particles (submicron), which are less affected by gravity, are used, but the scattered light intensity may be proportional to the sixth power of the particle diameter when the particle diameter is less than the wavelength of the irradiation laser. It is known that it is difficult to measure minute particles, especially in the case of minute and high-speed particles, the obtained scattering intensity is even smaller.

Further, since the conventional particle detecting device is constructed as described above, the sheet-like light rays are irradiated from two directions to prevent the particles from being missed, but the light rays are shaped. Since the galvanometer vibrates a single reflecting mirror to scan light and form an apparent sheet, there is a possibility of counting particles having a moving speed higher than the scanning speed of the galvanometer. Furthermore, even if high-speed scanning of the light beam is possible, the particle size required for detection in the semiconductor field and the like is becoming smaller, and the moving speed of particles is 10 m / s or more depending on the device for measuring particles. Because of the high speed, it is not possible to obtain a sufficient amount of scattered light for the measurement of such fine particles moving at high speed.
There was a high possibility of counting down, and there was a problem in accuracy. Further, in order to solve this problem with the conventional device, a high-speed light source that can obtain a sufficient scattering intensity from fine particles is required, and there is a limit to increase the power of the light source.

Further, the conventional foreign matter inspection apparatus for measuring particles is configured as described above, and the purpose is to measure the particles adhered on the wafer after the process is completed. It was not possible to determine at what stage of the process the adhesion had occurred. However, in order to elucidate the generation process of particles and reduce foreign particles, it is necessary to simultaneously measure the particles generated inside the process equipment and the particles attached to the wafer in real time, and to know the causal relationship between them. In order to solve this problem with a conventional device, it is necessary to separately install an adhered particle measuring device on a substrate such as a wafer and a suspended particle measuring device, which complicates the device configuration. Further, it is difficult to secure the mounting position of the ports for measuring both, and it is difficult to simultaneously install the two devices.

The present invention has been made to solve the above problems, and it is an object of the present invention to provide a particle measuring apparatus capable of accurately measuring particles or minute particles moving at high speed over a wide area. Another object of the present invention is to provide a particle measuring method capable of distinguishing particles adhered on a substrate such as a wafer and suspended particles with high accuracy by using the apparatus.

[0012]

According to a first aspect of the present invention, there is provided a light-scattering wide-area particle measuring apparatus for irradiating particles with a sheet-shaped light beam having a controlled thickness, and a sheet of the sheet-shaped light beam. It is provided with a photodetector for detecting light scattered in a direction perpendicular to the plane.

According to a second aspect of the present invention, there is provided a light scattering type wide area particle measuring apparatus which defines that the thickness of the sheet-like light beam is controlled by the moving speed of the particles.

In the light scattering wide area particle measuring device according to the invention of claim 3, the detector of claim 1 has a light accumulation effect.
It defines that it consists of a dimension detector.

The light-scattering wide-area particle measuring apparatus according to the invention of claim 4 defines that the measured area of the detector is controlled by the light-scattering volume.

According to a fifth aspect of the invention, there is provided a light-scattering wide-area particle measuring apparatus, wherein the means for controlling the measured area of the detector of the fourth aspect is an objective lens having a zoom mechanism.

The light-scattering wide-area particle measuring apparatus according to a sixth aspect of the present invention is provided with an image processing apparatus that integrates the images obtained by shifting the images detected by the detector in a specific direction. .

According to a seventh aspect of the present invention, there is provided a light-scattering wide-area particle measuring method, which comprises irradiating a substrate with a sheet-shaped light beam, and the light-scattering wide-area particle measuring device according to any one of claims 1 to 6. Is used to detect the scattered light from the particles, and the step of discriminating between the adhered particles and the suspended particles on the surface of the substrate by the time change of the detected value.

[0019]

In the light-scattering wide-area particle measuring apparatus according to the first aspect of the present invention, the thickness of the sheet-like light beam can be controlled, so that the light irradiation time is increased for high-speed particles and minute particles. And acts to increase the amount of light at the detector. The optimization of the beam thickness also improves the S / N ratio at the detector.

In the light scattering wide area particle measuring apparatus according to the second aspect of the present invention, since the thickness of the sheet-like light beam is controlled by the moving speed of the particles, it is possible to lengthen the light irradiation time for the high speed particles. Yes, it acts to increase the amount of light at the detector. The optimization of the beam thickness also improves the S / N ratio at the detector.

In the light scattering wide area particle measuring device according to the third aspect of the present invention, since the photodetector has a light accumulation effect,
By increasing the thickness of the sheet-like light beam and lengthening the light irradiation time, the amount of scattered light accumulated in the detector is increased and the S / N ratio is improved. As a result, the same operation as that in which the amount of scattered light is increased by using a high-power light beam is performed.

In the light-scattering wide-area particle measuring apparatus according to the fourth aspect of the present invention, the measured area of the detector is controlled by the light-scattering volume. Therefore, the light-scattering volume is increased by increasing the thickness of the light beam. However, even if noise is increased, the measured area of the detector is controlled according to the light scattering volume, and the scattering volume optimal for measurement is maintained.

The light-scattering wide-area particle measuring device according to the fifth aspect of the present invention is equipped with an objective lens having a zoom mechanism as means for controlling the measured area of the detector by the light-scattering volume, and is therefore optimum for measurement. It is possible to easily perform control for maintaining a large scattering volume.

According to a sixth aspect of the present invention, there is provided a light-scattering wide-area particle measuring apparatus in which the number n of areas in which particles pass through the measuring areas of the respective elements arranged two-dimensionally on the detector in the image processing device, Since it has a function to integrate images that have been shifted up to n-1 times in a specific direction within two dimensions, the amount of light received per element, such as particles that move diagonally in the detection direction, minute particles, and high-speed particles Is small or the S / N ratio is small, the plurality of images are integrated by shifting up to n-1 times, so that detection is possible. As a result, the same operation as that in which the amount of scattered light is increased by using a high-power light beam is performed.

The particle measuring method according to claim 7 of the present invention uses the light scattering wide-area particle measuring device according to any one of claims 1 to 6 to image-process scattered light from particles. Since the adhered particles on the wafer surface are stationary, there is no change in the position on the screen with respect to the time change, and it can be recognized.
Since the measurement can be performed by the method as described above, both can be measured simultaneously and can be easily distinguished.

[0026]

【Example】

Example 1. An embodiment of the inventions of claims 1, 2, 3, 4, and 5 will be described below with reference to the drawings. FIG. 1 shows an example in which the light-scattering wide-area particle measuring device according to the present invention is constructed in a bent exhaust pipe part of a process device, and a laser beam is used as a light beam. In the figure, 1 is a laser oscillator, 2 is a slit for controlling the beam thickness, 3,
Reference numerals 4 are plano-concave cylindrical lenses and plano-convex cylindrical lenses, respectively, which are optical systems for shaping the sheet-shaped laser beam 6 into a desired shape. Reference numeral 5 is a laser beam entrance / exit window for guiding the sheet-shaped laser beam 6 to the exhaust pipe 10 which is a particle measurement space, 7 is a light trap which is a stopper of the laser beam, and 8 is a two-dimensional detector having a light accumulation effect. , 9 is an objective lens having a zoom mechanism, 11 is a particle to be measured, 12 is a velocity meter for measuring a moving velocity of the particle, 13 is a moving direction of the particle, 14 is a velocity of the particle 11 measured by the velocity meter 12. Depending on the moving speed, slit 2,
A controller for controlling the objective lens 9 to shape the optimum laser beam or for controlling the optimum area to be measured, and 15 is an image processing device for performing image processing of the signal sent from the two-dimensional detector 8. .

FIG. 2 shows a conceptual diagram when particles 11 in the exhaust pipe 10 cross the sheet-shaped laser beam 6. The vertical division of the sheet-shaped laser beam 6 in the drawing indicates the area division detected by each detection element of the two-dimensional detector 8.
FIG. 3 shows the relationship between the scattering cross section of the medium and the S / N of the detector in the detector used in this example, which was calculated. In FIG. 2, when the area measured by each detection element of the two-dimensional detector becomes large, the scattered light from the medium becomes large, which causes an increase in noise. Therefore, the measurement region of each detection element of the two-dimensional detector is previously set so that the S / N ratio of the detector shown in FIG. 3 is high and the scattering cross section of the medium can be regarded as constant according to the particle diameter to be measured. Set it. In addition,
Here, an example in which the moving direction of particles and the sheet surface of the laser beam are arranged vertically will be described.

Next, the operation will be described. The laser beam emitted from the laser oscillator 1 is shaped into a desired sheet-shaped laser beam 6 by the slit 2 and the cylindrical lenses 3 and 4, and then introduced into the exhaust pipe 10. The scattered light of the particles 11 that have passed through the beam irradiation region reaches the two-dimensional detector 8 installed outside the exhaust pipe 10, and the output of the two-dimensional detector 8 is sent to the image processing device 15 to perform predetermined image processing. Be seen. Here, in order to secure a light amount that can be measured by the detector 8 for minute particles or high-speed particles, it is necessary to increase the laser beam irradiation time for the high-speed particles.
It is known that the thickness of the laser beam required for measurement is approximately proportional to the particle velocity. That is,
The faster the particle velocity, the thicker the laser beam thickness required.
Therefore, the moving speed of the particles is obtained by the velocity meter 12 installed in the exhaust pipe 11, and this is fed back to the slit 2 to control the thickness of the laser beam. In addition, the laser beam thickness is at most within the depth of focus of the two-dimensional detector, that is, at most 2 mm, so that the laser beam irradiation is always performed from when the particles enter the measurement area of one detection element to when they exit. The slit 2 controls the laser beam thickness.

In this example, the product of the measurement area measured by one detection element of the two-dimensional detector and the thickness of the laser beam is the scattering volume, which is proportional to the scattering cross section of the medium. Have a relationship. Therefore, increasing the thickness of the laser beam increases the scattering cross section of the medium, which causes an increase in noise. Therefore, the measured area is controlled by zooming the objective lens 9 so that the scattering cross section of the medium is constant so that noise is not increased, that is, the light scattering volume is constant.

In the image processing, a certain threshold is set in order to judge the presence of particles, and binarization is performed based on the threshold to obtain the coordinates and number of particles. Furthermore, the signal value of the particle is read from each coordinate and converted into the particle diameter. This makes it possible to obtain information about the fine particles or the fast particles.

In the above examples, the measurement space for particles was the exhaust pipe, but if the relationship between the detector and the scattering cross section of the medium is known, the measurement of particles in liquid such as a drain pipe may be used. .

In the above embodiment, an example using a laser beam is shown, but a light beam having a light intensity suitable for measurement may be used.

Example 2. An embodiment of the invention of claims 1 to 6 will be described below with reference to the drawings. FIG. 4 shows an example in which the light-scattering wide-area particle measuring device according to the present invention is configured at an arbitrary place in a certain process device, and laser light is used as a light beam. In the figure, the same reference numerals are used for the conventional example,
According to Example 1.

FIG. 5 shows a conceptual diagram when the particles 11 cross the sheet-shaped laser beam 6. The vertical division of the sheet-shaped laser beam 6 in the drawing with respect to the sheet surface indicates the region detected by each detection element of the detector 8. As described in the first embodiment, the region measured by each detection element of the two-dimensional detector is the scattering cross section of the medium shown in FIG.
It is optimized from the relationship of N ratio.

Next, the operation will be described. The sheet-shaped laser beam 6 is introduced into, for example, the exhaust pipe 10, and the scattered light of the particles passing through the beam irradiation region reaches the two-dimensional detector 8 installed outside the exhaust pipe 10, and the output of 8 is an image processing apparatus. It is sent to 15 and image processing is performed. The particle velocity is obtained by the velocity meter 12 installed in the exhaust pipe, and the width of the slit 2 is controlled according to the particle velocity. Further, the zoom mechanism of the objective lens 9 is controlled so that noise does not increase with respect to the movement of the slit width. In this case, in order to keep the scattering cross section of the medium constant, the laser beam thickness increases and the measurement area decreases as the particle speed increases.

FIG. 6 shows an example of image data sent to the image processing apparatus 15. In the figure, the trajectory of particles passes through n detection element measurement areas and moves on the screen divided area AA ′. If the particles move at high speed or are minute, the brightness obtained by the detector corresponding to this particle trajectory is very weak and S
The / N ratio is small. FIG. 7 shows the brightness of particles on the divided area AA ′. The signal before the image processing is the brightness shown by the solid line in the lower part of FIG. 7, which has a low S / N ratio and the presence of particles cannot be discriminated. The image obtained in FIG. 6 is referred to as a raw image and is referred to as image 0. FIG. 8 shows an example of the image processing method. One line, two lines, ...
And images that are sequentially deleted, that is, shifted in that direction by the deleted lines (referred to as image 1, image 2, ...) Are created. Here, the number of lines to be deleted, that is, the number of images to be created is a maximum of n−1 with respect to the measurement region n of the element when the particles pass the sheet-shaped laser beam 6. Image 1, image 2, ..., Image (n
-1) is added to image 0 as shown in FIG.
Due to the effect of integrating the light amount, the S / N ratio becomes high as shown by the solid line after the image processing in FIG. 7, and the particle discrimination can be easily performed.

After improving the S / N ratio by the integrated image processing as described above, in order to judge the existence of particles, a certain threshold value is set, and binarization is performed based on the threshold value. Find coordinates and number. Furthermore, the signal value of the particle is read from each coordinate and converted into the particle diameter. This makes it possible to obtain information about the fine particles or the fast particles.

In the above example, the measurement space of the particles was in a gas such as an exhaust pipe or in a vacuum, but if the relationship between the detector and the scattering cross-section of the medium is known, the particles in the liquid such as a drain pipe will be measured. It may be measurement.

Further, in the above example, the example using the laser beam is shown, but any light beam having a light intensity suitable for measurement may be used.

In the above example, the dividing method of image integration corresponds to the measurement area of the element, but the processing is performed by arbitrarily dividing in the moving direction of each particle on the image in which the brightness of the particle is recorded. You may go.

Example 3. Embodiments of the present invention will be described below with reference to the drawings. FIG. 9 is a diagram showing a particle measuring method using the light scattering type particle measuring device according to the present invention.
1a indicates suspended particles on the wafer 16, and 11b indicates adhered particles on the wafer 16. The same reference numerals are based on the conventional example or the first and second embodiments.

Next, the operation will be described. Here, the wafer 16 is horizontally irradiated with the sheet-shaped laser beam 6 adjusted to a desired shape and intensity by an optical system. Here, as shown in FIG. 9, the two-dimensional detector 8 and the wafer are in a vertical relationship, and the particles 11 adhered on the wafer in the beam irradiation region are
The scattered light from b or the suspended particles 11 a on the wafer reaches the two-dimensional detector 8, and the output of 8 is sent to the image processing device 15. The measurement area of each element of the two-dimensional detector is set to be equal to or less than the scattering cross-sectional area where the S / N ratio becomes constant according to the first and second embodiments.

The particles 11b adhering to the wafer 16 are always irradiated with the laser beam, and the scattering cross section of the medium is set to a small value as described above, so that the particles 11b are sufficiently scattered. The amount of scattered light is obtained. Therefore,
This image is binarized to obtain the particle coordinates and intensities and record them. Here, in the case of adhered particles, since the coordinates on the current screen and the previous screen are the same, it is possible to distinguish between adhered particles and moving particles by performing coordinate comparison.

Next, as shown in FIG.
Since a passes through the measurement regions of the plurality of detection elements of the two-dimensional detector, the amount of scattered light accumulated in each detection element is small and measurement becomes difficult. However, according to the image processing method shown in the second embodiment, the particles can be detected by shifting the images in the moving direction of the particles on the image processing screen and integrating them.
Then, a certain threshold is set to determine the presence of particles, and binarization is performed based on the threshold to obtain the coordinates and number of particles and the particle diameter. Further, the number of the adhered particles stored previously is compared. The number of times of this integration is controlled by the particle velocity.

In the above embodiment, an example using laser light is shown, but a light beam having a light intensity suitable for measurement may be used.

Example 4. Hereinafter, another embodiment of the present invention will be described with reference to the drawings. FIG. 10 is a diagram showing a particle measuring method using the light scattering type particle measuring device according to the present invention, in which 17 is a moving direction of the wafer 16, arrows B and B ′ are laser beam irradiation directions, and θ is a laser for the wafer 16. The irradiation angle of the beam 6. FIG. 11 shows another particle measuring method using the light scattering type particle measuring device according to the present invention. In addition, the same code | symbol follows a prior art example or Examples 1-3.

Next, the operation will be described. Here, the sheet-shaped laser beam 6 adjusted to have a uniform intensity is applied to the wafer 16
Irradiate from diagonally. Here, as shown in Example 3, the adhered particles 11 on the wafer existing in the beam irradiation region
Light scattered from b and the suspended particles 11a on the wafer reaches the two-dimensional detector 8, and the output of 8 is sent to the image processing device 15. The measurement region of each element of the two-dimensional detector is set to be equal to or less than the scattering cross-sectional area where the S / N ratio becomes constant according to the first and second embodiments.

The particles 11b adhering to the wafer 16 are always irradiated with the laser beam, and the scattering cross section of the medium is set small as described above. The amount of scattered light is obtained. Therefore,
This image is binarized to obtain the particle coordinates and intensities and record them. Here, in the case of adhered particles, since the coordinates on the current screen and the previous screen are the same, it is possible to distinguish between adhered particles and moving particles by performing coordinate comparison.

Next, as shown in FIG. 10, suspended particles 1
Since 1a passes through the measurement regions of a plurality of detection elements of the two-dimensional detector, the amount of scattered light accumulated in each detection element is small and measurement becomes difficult. However, according to the image processing method shown in the second embodiment, the particles can be detected by shifting the images in the moving direction of the particles on the image processing screen and integrating them. Then, a certain threshold is set to determine the presence of particles, and binarization is performed based on the threshold to obtain the coordinates and number of particles and the particle diameter. Further, the number of the adhered particles stored previously is compared. The number of times of this integration is controlled by the particle velocity.

In the above embodiment, an example in which a laser beam is applied to a certain plane is shown, but the wafer 16 is scanned in the direction of arrow 17 shown in FIG. Needless to say, it is possible to cover measurement in a wide area.

Although the floating particles move in the wafer direction as represented by the arrow 13 in the above embodiment, the moving direction is not limited. Further, if the moving direction is a direction that does not pass through a plurality of elements, that is, a direction perpendicular to the sheet surface of the laser beam, while satisfying the relationship that the sheet surface of the laser beam and the direction of the detector are perpendicular, The irradiation angle θ of the beam 6 may be controlled so as to pass through the measurement regions of a plurality of elements.

In the above embodiment, the position of the detector is arranged with respect to the incident direction B of the laser beam, but as shown in FIG. 11, the direction in which the laser beam is reflected from the wafer is shown. A detector may be arranged with respect to B ′ to perform measurement.

In the above embodiment, an example using a laser beam is shown, but a light beam having a light intensity suitable for measurement may be used.

[0054]

As described above, according to the first aspect of the present invention, by controlling the thickness of the sheet-like light beam used for particle measurement, the light quantity at the detector is insufficient and the S / N ratio is poor. Since the above is eliminated, particles are not counted down over a wide area covered by the sheet-shaped laser beam, and the measurement accuracy is improved.

As described above, according to the invention of claim 2,
In addition to the effect of the first aspect, the moving speed of particles is measured at the same time during particle measurement, and the thickness of the sheet-like light beam is controlled accordingly, so that the measurement accuracy is further improved.

As described above, according to the invention of claim 3,
In addition to the effects of the first and second aspects, the integrated light amount at the detector also increases and the S / N ratio improves, so the measurement accuracy is further improved.

As described above, according to the inventions of claims 4 and 5, in addition to the effects of claims 1 to 3, for example, by using an objective lens having a zoom mechanism, the measured area of the detector is scattered by light. Since it is controlled by the volume, noise is reduced and the measurement accuracy of particles in a wide area is further improved.

As described above, according to the invention of claim 6,
In addition to the effects of claims 1 to 5, the simple image processing function enables the detection of high-speed particles and minute particles with a small amount of light and a low S / N. improves.

As described above, according to the inventions of claims 1 to 6, the device can be configured at any place by fixing the sheet surface of the sheet-like light beam, that is, the scattered light and the direction of the detector. Can be compactly installed even in a limited installation area.

As described above, according to the invention of claim 7,
Since the particle measurement is performed using the light-scattering wide-area particle measuring device according to claims 1 to 6, even if the moving particles are high-speed or minute, and the adhered particles are minute, both It is possible to simultaneously measure with high accuracy and measure. Also, since two types of particles can be measured with one device, the device configuration is simple and can be compactly arranged in a limited installation area.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of a light scattering wide area particle measuring device according to a first embodiment of the present invention.

FIG. 2 is a detailed sectional view of a portion to be measured in the light-scattering wide-area particle measuring device according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between a scattering cross section of a medium and an S / N ratio in a detector.

FIG. 4 is a perspective view showing a configuration of a light scattering wide area particle measuring device according to a second embodiment of the present invention.

FIG. 5 is a detailed sectional view of a portion to be measured in the light scattering wide area particle measuring device according to the second embodiment of the present invention.

FIG. 6 is a schematic view showing an image of particles measured by a light scattering wide area particle measuring device according to a second embodiment of the present invention.

FIG. 7 is a diagram showing luminance values of particles measured by a light-scattering wide-area particle measuring device according to a second embodiment of the present invention before and after image processing.

FIG. 8 is a schematic diagram showing an image processing method to be executed in the light scattering type wide area particle measuring device according to the second embodiment of the present invention.

FIG. 9 is a schematic view showing a particle measuring method using a light scattering wide area particle measuring device according to a third embodiment of the present invention.

FIG. 10 is a schematic diagram showing a particle measuring method using a light scattering wide area particle measuring device according to a fourth embodiment of the present invention.

FIG. 11 is a schematic view showing another particle measuring method using the light scattering wide area particle measuring device according to the fourth embodiment of the present invention.

FIG. 12 is a diagram showing a conventional flow visualization device.

FIG. 13 is a diagram showing a conventional particle measuring device.

FIG. 14 is a diagram showing a conventional foreign matter inspection device.

[Explanation of symbols]

 1 Laser Oscillator 2 Slit 3 Plano-Concave Cylindrical Lens 4 Plano-Convex Cylindrical Lens 5 Laser Beam Entrance / Exit Window 6 Sheet Laser Beam 7 Light Trap 8 Two-Dimensional Detector with Light Storage Effect 9 Objective Lens with Zoom Mechanism 10 Exhaust Pipe 11 Particle 12 Velocity meter 13 Particle moving direction 14 Controller 15 Image processing device 16 Wafer 17 Wafer moving direction 18 Camera 19 Polyhedral reflecting mirror 20 Motor 21 Rod lens 22 Nozzle 23 Light source 24 Half mirror 25 Galvanometer 26 Transparent cell 27 Detection part 28 Processing part 29 Objective lens 30 Photodetector 31 Sample stage

Claims (7)

[Claims] 1. A means for irradiating a particle with a sheet-shaped light beam having a controlled thickness, and a detector for detecting light scattered by the particle in a direction perpendicular to a sheet surface of the sheet-shaped light beam. Light scattering type wide-area particle measuring device equipped. 2. The light scattering wide-area particle measuring device according to claim 1, wherein the thickness of the sheet-like light beam is controlled by the moving speed of the particles. 3. The light-scattering wide-area particle measuring apparatus according to claim 1 or 2, wherein the detector is a two-dimensional detector having a light accumulation effect. 4. The light-scattering wide-area particle measuring device according to claim 1, further comprising means for controlling a measured area of the detector by a light-scattering volume. . 5. The light scattering wide-area particle measuring device according to claim 4, wherein the means for controlling the measured area of the detector is an objective lens having a zoom mechanism. 6. The light-scattering system according to claim 1, further comprising an image processing device that shifts and integrates the images detected by the detector in a specific direction. Wide area particle measuring device. 7. A step of irradiating a substrate with a sheet-shaped light beam, and the sheet scattered by particles by a light-scattering wide-area particle measuring device according to claim 1. Particle measuring method comprising: a step of detecting scattered light of a circular light beam; and a step of discriminating between particles adhering to the substrate and suspended particles based on a time change of a detection value.