JP2750082B2 - Particle detecting apparatus and method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a new apparatus and method for particle detection, and more particularly, to an apparatus and method capable of detecting and separating particles with high efficiency and in situ.
The present invention relates to a particle measurement / counting system, and more particularly to a measurement / counting system having improved applicability to particle detection, having particular applicability for use in vacuum lines and semiconductor processing equipment.

[0002]

2. Description of the Related Art The use of particle measuring or particle separating devices is increasing. The single largest application is the semiconductor industry, where cleanliness is very important in semiconductor fabrication. For example, particle counting is used to monitor the number of particles in a room called a clean room where semiconductor manufacturing operations are performed. Normally, a clean room is
Classification is generally based on the maximum number of particles of a given size allowed per volume. In order for the product to be produced to meet specifications and maintain quality levels, it is necessary to ensure that particulate contaminants are kept to the minimum acceptable requirements.

[0003] The basic system most used for particle counting in air sends an air stream of the sample into a light beam, so that the light energy is scattered by the particles. This scattered energy is detected and measured by appropriate optics and electronics. Significant improvements have been made to the optics and electronics used to detect and process the scattered light signal. The advent of lasers has also greatly improved the quality and brightness of the illuminating light beam.

[0004] Despite these improvements, the accuracy of the data output from the devices has not yet reached the desired accuracy. Each test also showed other inaccuracies, such as, for example, particle recirculation, discrepancies in absolute counting correlation between different devices.

Another problem with this particle detection is that
The problem has been solved by the development of a particle measurement system that includes the particles to be detected or measured in a flowing stream that passes through a light beam, typically a laser light beam. As mentioned above, particles passing through the beam scatter light,
The scattered light is captured by one or more photodetectors and focused to generate electrical pulses. The intensity of the scattered light and, therefore, the amplitude of the pulse generated by the photodetector gives an indication of the size of the particles.

[0006] In many systems, it is important to detect any particles in the contained flow stream. This requires that the light beam pass through the entire cross-sectional area of the flow stream containing the particles. If the flowing stream is a liquid stream, the conduit carrying the stream through the light beam will generally narrow along the way and have a narrow cross-sectional area so that the high intensity beam can pass through the entire cross-sectional area of the flowing stream. If the flow stream containing the particles is a gas stream of substantial density, the seeded gas stream is forced into a sheet shape by a nozzle and the laser beam is applied, for example, by Kenneth P.M. G
As described in U.S. Pat. No. 4,746,215 to ross, it can pass along a long width of a sheet-shaped stream. The nozzle of this device has a gradual cross-sectional area change that does not significantly affect the ability of suspended particles to closely follow the flow rate of the gas stream line (i.e., there is a separation between the particles and the gas phase). Does not occur).
However, when the particles are in a vacuum as in a semiconductor processing apparatus, it is difficult for the nozzle to form the stream into a sheet. Further, for a vacuum line to efficiently transmit a vacuum to a semiconductor processing area, the vacuum line must have a substantial cross-sectional area. Thus, prior art particle detection systems having narrow conduits or nozzles create a flow stream where particle detection is unsatisfactory in vacuum lines such as those used in semiconductor processing equipment.

Although thin film technology is used in the manufacture of semiconductors and packaging devices, a major obstacle to yield is defects due to particle contaminants on the thin film surface. A major cause of such defects is due to contaminant particles produced by processing equipment or tools used to manufacture thin film devices, author Bowling, R.A. The following article by A et al. "Status and needs
of in-situ real-time process particle detection ",
J. Environ. Sci, Vol. 32 (5), pages 22-27 (198
9 years).

Many processing equipment used in the thin film manufacturing or semiconductor industries operate at low pressures (eg, RI
E, PECVD). These in-situ particle monitoring tools are frequently used to detect contaminants and control processing equipment for contaminants, and in most cases,
It is installed in the discharge line of the processing room.

[0009] Currently available vacuum line monitors are:
In general, the light scattering is used to
Detect particles in the gas passing through the section to be irradiated with the beam. Please refer to the following article for this. Greenstein, D. "Invest
igating a Prototype In Situ ParticleMonitor on the
Exhaust Line of a CVD Reactor ", Microcontaminatio
n, Vol. 3, pages 21-26 (1991), and Stern,
J. E. "MonitoringDownstream Particles in a
Single-Wafer CVD Oxide Reactor ", Microcontaminati
on, Vol. 11, pages 17-56 (1991). In the means described above, a single focused laser beam is used to illuminate a narrow portion of the fluid passage cross section. Only a very narrow portion of the fluid particles is illuminated and detected. The low detection efficiency of such particle monitors (on the order of 0.1% to 3.0%) produces poor quality particle count statistics,
As a result, monitors are not used in statistical process control (SPC) applications.

[0010] A number of attempts have been made to solve the low detection efficiency. In one case, multiple reflected beams were used to create a "sheet" or "net" of light that increased the illumination area in a vacuum conduit. This is described in U.S. Pat. No. 4,739,177 to Borden. However, Caldow, R .; The voluntary work described below by A. et al. Only slightly improved the system efficiency described by Borden and others. "Performance of the High Y
ield Technology Inc. PM-100 In SituParticle Flux M
onitor ", Aerosol Science Technology, Vol. 12, page
s 981-991 (1990). The result is High Yield Tec, assignee of Borden U.S. Patent No. 4,739,177.
Using a multiple reflection beam system manufactured by hnology, the monitor counting efficiency was 4.7% at 6.0 micron particles and only 0.1% at 0.5 micron particles.

[0011] US Patent No. 50 recently issued to Sommer
The device of 92675 uses a single sheet of laser light to illuminate the entire cross-sectional area of the vacuum conduit so that all particles flowing through the conduit can be detected. this is,
The irradiated cross section is increased, however, the state of the art requires a significantly higher power laser to detect the smallest detectable particle size.

[0012] Thus, further improvements in particle detectors or particle counters are desired.

The invention described herein also detects particles by scattered light. However, the new design utilizes a light source, beam optics, light-sensing elements, and a single, aerodynamically focused cross-section of the suspended particles in the fluid stream to a narrow focal area compared to the nozzle exit area. A specially designed system using the nozzle design of the above is used. The focal zone is illuminated by one or more narrow, high-intensity light beams, preferably a focused laser beam, where a significant number of particles (nearly 100% expected) of the fluid stream's particles are detected. it can. The high efficiency particle detection provided by this new invention is suitable for many industrial applications such as SPC applications.

[0014]

SUMMARY OF THE INVENTION The present invention is a new method and apparatus for detecting particles in situ within a fluid stream with high efficiency.

It is an object of the present invention to provide an apparatus and method for detecting particles in a highly efficient and in-situ position.

It is another object of the present invention to provide a particle detector that operates in a vacuum with high efficiency.

It is a further object of the present invention to provide a particle detector that works online in a semiconductor process.

Yet another object of the present invention is to provide a particle detector having an adjustable nozzle that can change the focal position of the detected particles.

Yet another object of the present invention is to provide a particle detector having slidable means for varying the distance between the nozzle and the light beam used to detect the particles.

[0020]

SUMMARY OF THE INVENTION A feature of the present invention comprises an apparatus for detecting particles flowing through a fluid conduit. The fluid conduit has the following configuration. A nozzle having at least one focusing means for aerodynamically focusing said particles in a focal zone, wherein a cross-sectional area of said focal zone is substantially smaller than a cross-sectional area of said focusing means; At least one means for illuminating the focal zone with two narrow light beams and at least one means for detecting scattered light by the particles illuminated by the light beams.

Another feature of the present invention is to include a method for detecting particles flowing in a fluid conduit configured as follows. (A) aerodynamically focusing particles detected by the at least one focusing means into a focal zone, wherein the cross-sectional area of the focal zone is smaller than the cross-sectional area of the focusing means;
(B) illuminating the focal region with at least one narrow light beam such that the light beam is scattered by the particles in the focal region; and (c) scattered by the particles illuminated by the light beam. A method further comprising detecting the light and counting the number of particles in the focal zone detected in the detecting step.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In operating a sensing system to determine the number of particles in a fluid stream, such as a gas or liquid, it is assumed that particulates are suspended in the fluid. In general, the gas or liquid acts as a carrier, transporting suspended particles through the focus of a light beam, such as a laser beam, used by the sensing system. Since the suspended particles scatter light and can be detected, the physical characteristics of the particles, such as the size and number of the particles, can be known. Perform particle detection for various reasons. For example, by way of a few examples, knowing the number and size of particles scattered into the environment can tell if the contamination exceeds a specified process or environmental limit.

A preferred nozzle embodiment is shown in FIG. The rapidly converging nozzle 10 has a nozzle housing 12 and is covered by one or more upper fixed or movable nozzle plates 14 and one or more lower fixed or movable nozzle plates 16. Have been done. The nozzle housing 12 is preferably tubular, but may be of any shape. The nozzle housing 12 is preferably circular and has a nozzle opening or nozzle outlet 15 for allowing the flowing particles 11 and 13 to flow out. For the purposes of the illustration, only the flowing particles 11 are possibly carrier fluids or gases and the flowing particles 13 are referred to as particles to be detected, or unwanted particles or contaminants.

The upper plate 14 generally has an angle 4 shown in FIG. This angle 4 is 90 degrees depending on the process conditions.
It can be changed in the range of degrees to 135 degrees. Similarly, the lower plate 16 has an angle 6. This angle 6 can also vary between 90 and 135 degrees depending on the process conditions. In general operation, it has been found that the preferred angle of angles 4 and 6 in the figure is 90 degrees.

Plates 14 and 16 may be the same or different sizes. Similarly, plates 14 and 16 may be rectangular or semi-circular or other shapes. Nozzle 10
Single plate 17 instead of plates 14 and 16
Which is preferably a circular outlet or opening 15 for the passage of flowing particles 11 and 13
Having. Similarly, plate 17 has a variable opening 15, such as an iris, to alter the characteristics of the fluid flow. The angle between the angles 4 and 6 of the plate 17 is preferably 90 degrees, but it is better to change the angle according to the application.

The fluid flow in a typical situation has one or more carrier fluids 11 containing one or more unwanted particles 13 that must be detected or counted.
In semiconductor processing, the carrier fluid 11 is generally a gas, to name a few, for example, nitrogen, helium, hydrogen, argon, oxygen or a mixture of gases,
And the flowing particles 13 are certain contaminant particles that generally penetrate during the semiconductor manufacturing process. Generally fluid particles 13
Has a much larger mass than the carrier gas molecules 11.

As the fluid containing gas and contaminant particles passes through the focusing nozzle 10, the heavy particles 13 become lighter gas particles 1
And a fluid or particulate gas jet results. As shown in more detail in FIG. 1, the flowing particles 11 converge closer to the nozzle opening or outlet 15 and diverge immediately after passing through the opening 15 without much compression. On the other hand, the suspended contaminant particles 13 also
As it approaches the nozzle outlet or opening 15, it converges, but due to its large momentum, i.e. inertia, its convergent movement tends to stay downstream of the nozzle opening or outlet and if its weight is sufficient, , Finally crossing the jet axis at a common focal point or focal zone 26. Unlike the flowing particles 11, the contaminant particles 13
, Resulting in a very dense local particle concentration in the area. The fluid flow downstream of the nozzle is thus separated into a region 23 where the particles 13 are concentrated and a region 21 where the particles 13 are reduced and is divided by an imaginary surface or region 20. In summary, the focusing nozzle 10 mainly concentrates the heavy particles 13 to reduce the narrow focal region 26.
But also does not restrict the light gas particles 11.

Reference is made to the following literature, which is a recent theoretical and experimental study which describes in detail the phenomenon of selective particle focusing described above. Fernandez de la Mora,
J. , Rossell-Llompart, J .; And Riesco-Chueca, P .;
(1989) "Aerodynamic Focusing of Particles an
d Molecules in Seeded Supersonic jets ", fromRarefi
ed Gas Dynamics: Physical Phenomena, Muntz, E.
P. Weaver, D .; P. And Campbell, D.C. H. , Eds. Vo
l. 117 of Progress in Astronautics and Aeronautic
s, AlAA, Washington D.S. C. For example, Fernandez de la
Figure 2 on page 252 of the aforementioned article by Mora et al. Shows the trajectory of heavy particles seeded in a light gas as the particle-containing gas flows through a rapidly converging nozzle. Heavy phase particles tend to concentrate along the nozzle axis downstream of the nozzle. Particles with sufficient inertia intersect the nozzle axis at a common intersection point or focal point, and the location of the intersection depends on flow rate, nozzle geometry, particle inertia, and to some extent upstream of the nozzle where the particles seed. Involved. Apart from the inertia of large particles, the position of the focal point is theoretically independent of the flow and the parameters of the particles, but as seen for particles from substantially different positions upstream of the nozzle, the "geometric aberration" Affects the optical system as well. However, in a fixed nozzle operating over a wide range of flow conditions, most of the particles orbitally pass through a focal zone that is much smaller (on the order of a few percent) than the exit of the nozzle. The focal zone 26 is generally located at a distance less than the exit dimension of the nozzle in a direction downstream from the opening or exit 15 and the phase of the particles is concentrated up to 1000 times in this region.

The phenomenon in which particles are concentrated by inertia greater than that of the carrier fluid is strictly referred to in the technical literature as "aerodynamic focusing". As an example, the Fernandez de
See laMora et al.

FIG. 2 is a schematic diagram of a preferred embodiment of the present invention. The device 25 of the invention in a typical application is inserted between the two fluid conduit sections 32 and 34 of the flow conduit carrying the particle-containing gas and is secured by suitable coupling or securing means 31 and 33. Fluid conduit 32 is the inlet of the flow conduit, while fluid conduit 34 is the outlet of the flow conduit.

The opening or outlet 15 is preferably circular to ensure that contaminated or unwanted flowing particles 13 are focused. The diameter of the opening 15 is
It must be at least less than one-half of the zero entrance. The particles 13 approaching the nozzle 10 are arbitrarily dispersed in the carrier gas and create appropriate conditions by passing through the nozzle 10 so that all the particles 13 are focused and located on the nozzle axis 27. Narrow focus area 2
Flow through 6. By appropriately changing the shape parameters of the nozzle, for example by changing the diameter of the nozzle opening or nozzle outlet 15 relating to the diameter of the inlet, the focal zone 26 can be varied at different distances from the outlet or opening 15. Can be located. The optimal design of the nozzle 10 will, of course, depend on the physical characteristics of the particles being detected, the characteristics of the carrier fluid flow, the number of particles detected, and the like.

In most applications, the focal zone 26 will be located downstream from the nozzle opening or outlet, and will typically be a distance of 0.5 to 3 times the diameter of the nozzle opening or outlet. know. A focal zone 26 having a smaller cross-sectional area compared to the nozzle outlet or opening 15 is illuminated by a high intensity light beam 22 that is narrower and focused than the particle stream in the focal zone 26. The intersection of the two focal points (ie, light beam 22
And the stream of particles 13)
Is detected and can be counted. It is conceivable that the use of this device of the invention results in a very high particle detection efficiency approaching 100% over currently available similar means without a focusing nozzle.

A narrow light beam 22, such as a laser beam, is applied to the light source 18, preferably a laser diode.
To focus the light beam 22 on the focal zone 26 using a suitable collimator 28. The scattered light is received by the light receiving unit 29
Is collected by a photodetector 19, preferably a solid state photodetector or photomultiplier.
The incident light beam terminates at a light stop 24 in the forward scattering configuration shown in FIG. The light stop 24 prevents the incident light beam 22 from reaching the detector 19, so that the detector 19 detects only the scattered light from the particles. Particles 11 and 13 passing through device 25 are generally discharged through the outlet of flow conduit 34 using a pump.

As can be seen from FIGS. 1 and 2, the maximum concentration of the particles 13 to be counted lies in the focal zone 26. Therefore,
To obtain the maximum density count, the nozzle axis 27 and the optical axis 37
Must intersect at an angle of 90 degrees, so that the focal point of the light beam can optimally intersect the focal point of the particle stream.

The opening 15 of the nozzle 10 for sharply converging
Is generally smaller than the conduit, but larger for the thickness of the focused light beam 22. This allows an effective vacuum to be sent through the nozzle without extreme resistance.

For most applications, the sensing optics and the flowable particles are preferably within housing 30. The housing 30 also protects the focal zone 26 from external influences, such as ambient air vibrations and light from unwanted sources.

Another preferred embodiment of the device of the present invention is shown in FIG. The device 35 of the present invention is very similar to the device 25, except that the light source 18 is substantially coaxially aligned with the nozzle 10. When the angle of the intersection 7 between the nozzle axis 27 and the light beam axis 37 is small, a long portion of the nozzle axis is irradiated. Light beam 2 in extreme cases
2 may be coaxial with the nozzle 10. In this embodiment, the particles 13 at the nozzle 10 will intersect the axis at a slightly altered distance from the nozzle outlet 15, since the geometrical aberrations are not so significant.

As shown in FIG. 3, the distance between the nozzle outlet, that is, the opening 15 and the axis of the light beam 37 is adjustable. This change in distance can be achieved, for example, by mounting the nozzle 10 on a suitable movable means 39 such as a bearing,
In the axial direction or the housing 30 of the optical device in the axial direction. Similarly, the nozzle 10, the optical system, or both can be moved using a telescoping scheme to achieve the desired result.

FIG. 5 illustrates another embodiment of the present invention, in which a dust collecting means or removing means 50 for removing particles 13 from a fluid stream is shown. The removing means 50 is placed at or near the focal zone 26. Therefore, the high concentration region 2 of the fluid flow
3 is removed by the removal means 50, while the lean zone 21 of the fluid stream substantially bypasses the removal means 50. For removal in close proximity to the focal zone 26, the removal means 50 defines a limit for removing the high concentration zone 23 of the fluid stream. The closer the removal means 50 is to the focal area 26, the higher the concentration 23 of the fluid flow.
Is further removed. The removal means can be used in conjunction with the light beam 22 and associated devices, as shown in FIG. 5, to count the particles before performing the removal. Instead, light beam 2
There is also a method in which the 2 and related devices are removed and the particles are simply removed and counted later. The removal device 50 may have a tube 56 into which the flow of the high concentration region 23 enters. Since the tube 56 intersects the fluid flow at or near the focal zone, the cross-sectional area (or diameter) of the tube 50 is the cross-sectional area (or diameter) of the nozzle 15.
Less than. If necessary, a pump 52 is added. Tube 56 removes particles 13 from the fluid conduit and passes through via conduit 54 for further processing. After passing through the fluid conduit 34 via the tube 56, the particles can be counted at a location if necessary.

FIG. 4 is a schematic diagram illustrating a practical process utilizing the present invention. Processing apparatus 40 having processing chamber 45
Has a fluid processing inlet 42 and a fluid processing outlet 44.
As shown in FIG. 4, the apparatus of the present invention has a flow treatment inlet 4
2 or flow treatment outlet 44 or both. As a result of the work in the processing chamber 45, in order to obtain an accurate count of the particles introduced into the flow stream,
The sensing system of the present invention may be located at both the flow processing inlet 42 and the flow processing outlet 44. Also, care must be taken to keep the particle detectors of the present invention sufficiently far from the processing chamber 45 so that these particle detectors are not adversely affected by any of the processing that occurs within the processing chamber 45.

The present invention also includes an apparatus and method for detecting and separating particles at high efficiency and in situ. The present invention provides for the efficient separation and measurement of particles, especially particles in a gas. The invention is needed in many industrial applications. Such industries include, for example, the semiconductor industry, the pharmaceutical industry, the environment-related industry, and others. Perhaps the area where the present invention is most used is in the semiconductor industry where cleanliness in semiconductor fabrication is very important. The present invention not only allows measurement of particles, but also separates useful and useless particles. Similarly, in the pharmaceutical industry, separation of particulates is desired so that certain drugs are processed into a finely divided state. Environment-related applications provide sampling for detailed analysis and enrichment of aerosols in diluted environments. Of course, there are many devices currently in use, such as filters and impactors, for separating particles from a gas stream. These devices generally collect particles on the surface of the element that block the flow.
However, the present invention not only measures flowing particles at the same position, but also separates particles of the same type with high efficiency.

According to the present invention, as shown in FIG.
A nozzle 10 is used that is aligned with the removal means 50, which is a probe or collector downstream of zero. Generally, the flow through the nozzle 10 is subsonic,
There is no need to vent the stream leaving 0 into a vacuum. Under properly selected flow conditions, the nozzle 10 aerodynamically focuses, i.e., focuses, the particles 13 in the fluid into a focal zone 26 that is smaller in size than the nozzle exit. The probe or removal means 50 used has an inlet generally smaller than the size of the outlet of the nozzle 10. The probe or removal means 50 is preferably aligned with the nozzle axis and is positioned so as to approach or overlap the focal zone 26 of the particles. A small portion of the center of the gas stream exiting the nozzle 10 is very rich in particles by focusing and is drawn through the probe or removal means 50. That is, the remainder, which is extracted while the carrier gas 60, which is generally "clean", is released along the outer wall of the removal means 50. Preferably, the flow through the removal means 50, which is a probe, is uniform. That is, the velocity of the gas or particle passing through the probe inlet is equal to the velocity of the flow upstream of the probe. Constant velocity sampling is generally useful for reducing particle loss to the probe wall. This has not been possible with prior art means, which generally have a larger collection opening diameter than the outlet of the nozzle.

As shown in detail in FIG. 5, there is shown a removal means 50 which is a collector or probe for removing particles 13 from the fluid stream. The removal means 50 is located at or near the focal zone 26. In this way, the fluid in the high particle concentration region 23 which is a fluid flow is removed by the removing means 50. On the other hand, the fluid in the particle-lean region 21, which is a fluid flow, substantially bypasses the removing means 50 and exits as “clean” carrier gas 60. The degree to which the removal means 50 is close to the focal region 26 determines the degree to which the fluid in the high concentration region 23 in the fluid flow is removed.
The closer the removal means 50 is to the focal zone 26, the more fluid in the high density zone 23 in the fluid flow is removed. Removal means 50
Can be used in conjunction with the light beam 22 and associated equipment as shown in FIG. 5 and can be counted before removing particles.
Alternatively, the light beam 22 and associated equipment can be removed and the particles simply removed before counting. The removing device 50 has a pipe 56 into which the fluid in the high concentration region 23 flows.
In order for the tube 56 to intersect with the fluid flow at or near the focal zone 26, the cross-section (or diameter) of the tube or pipe 50 is smaller than the cross-section (or diameter) of the nozzle opening or outlet 15. If necessary to remove particulates, a pump 52 is added. Tube 56 is
Particles 13 are removed from the fluid conduit for processing in via conduit 54. After the particles exit the fluid conduit 34 by the tube 56, the particles can be counted at some point, if desired. Similarly, the removed particulates can be delivered for further processing. This may include treating the drug in particulate form or removing these particulates from the closed loop system.

Of course, the present invention also provides aerodynamic focusing of the separation of heavy particles from light particles, or the re-separation of already separated particles, or selective focusing of particles to selectively separate particles. Can also be used for separation

Further, it is generally good to detect the forward scattered light from the particles 13. The device of the present invention is not limited in its configuration, and angle-free detection can be used as well.

In some applications, it may be advantageous to use a rectangular nozzle opening 15. In this case, a large aspect ratio is formed in the opening 15, and the suspended particles 13 are converged, for example, when flowing through a rectangular slit whose vertical width is longer than the horizontal width. The focal zone 26 in this case has a length transverse to the fluid flow, corresponding to the length of the slit. The light beam 22 illuminates the particles across the walls of the flow conduit along the entire length of the passing particles.

Another configuration of the nozzle 10 has an adjustable outlet or opening 15 to extend the use of the device of the present invention in a wide range of pressures and flow rates. In place of the iris diaphragm 17 due to the configuration of the axisymmetric shape, for example,
Variable shapes may be obtained that are used in camera openings or the like in place of plates 14,16. In the case of a rectangular shape, a variable slit opening 15 can be used using two coplanar plates 14 and 16 moving in opposite directions.

The device of the present invention can operate under subsonic and supersonic flow conditions. Particle focusing is observed at subsonic and supersonic velocities through the aforementioned nozzles, however, it is generally advantageous to operate under subsonic conditions in many of the intended applications of the device. Because of the constant pumping capacity, subsonic flows are generally operated with large diameter nozzles, resulting in a correspondingly small pressure drop across the nozzle. At subsonic velocities and pressure ranges from 0.1 Torr to 10 Torr, most nozzles are 3 m
m, while in such applications the focused laser beam preferably has a thickness of about 1 mm or more. If the flow velocity is supersonic, a nozzle smaller than 1 mm is required.

Although this specification has been described with reference to certain preferred embodiments, it will be apparent to those skilled in the art that many alternatives, modifications, and variations are possible within the scope described above. Accordingly, the appended claims encompass any alternatives, modifications and variations within the spirit and scope of the invention.

Hereinafter, the embodiments will be summarized and described. (1) A device for detecting particles flowing in a fluid conduit, the nozzle having at least one focusing means for aerodynamically focusing the particles on a focal region, wherein the nozzle has a focus region. A cross-sectional area substantially smaller than a cross-sectional area of the focusing means, and at least one for illuminating the focal zone with at least one narrow light beam.
And an at least one means for detecting scattered light of the particles irradiated by the light beam. (2) The apparatus according to (1), wherein the focusing means is a nozzle that sharply converges. (3) The apparatus according to (2), wherein the nozzle is substantially axisymmetric. (4) The apparatus according to (2), wherein the nozzle is substantially rectangular. (5) The apparatus according to (2), wherein at least a part of the cross-sectional area of the nozzle is adjustable. (6) the velocity of the fluid flow through the nozzle is subsonic;
The device according to (2). (7) The apparatus according to (1), wherein the light beam substantially crosses the focal region from a lateral direction. (8) The apparatus according to (1), wherein the light beam crosses the focal region from a substantially coaxial direction. (9) The apparatus according to (1), wherein the focusing unit includes a unit that can change a distance between the focal area and the focusing unit. (10) The distance between the nozzle and the focal region irradiated by the light beam is at least 3 times the nozzle width.
The device according to (2), which is one-third. (11) At least one for moving the focusing means
The device according to (1), comprising: (12) The apparatus according to (1), wherein the particles to be detected are carried by at least one carrier fluid. (13) The device according to (12), wherein the at least one fluid is at least one gas. (14) The apparatus according to (1), wherein the at least one light beam is a laser beam. (15) The at least one means for detecting the scattered light includes at least one means for electrically calculating the scattered light.
The device according to (1), comprising: (16) at or near the focal zone, further comprising at least one means for removing at least a portion of the particles from the focal zone and the fluid conduit; (1)
It is a device of the description. (17) The apparatus according to (16), wherein the removing means is a tube. (18) A method for detecting particles flowing in a fluid conduit, comprising: (a) aerodynamically focusing particles detected by at least one focusing means into a focal zone, wherein A cross-sectional area smaller than the cross-sectional area of the focusing means; (b) illuminating the focal region with at least one narrow light beam such that the light beam is scattered by the particles in the focal region; The method further comprising detecting the scattered light by the particles illuminated by the light beam and counting the number of particles in the focal zone detected in the detecting step. (19) The method according to (18), wherein the focusing means is a nozzle that sharply converges. (20) the nozzle is substantially axially symmetric; (19)
It is the method described. (21) the nozzle is substantially rectangular; (19)
It is the method described. (22) The method according to (19), wherein at least a part of the cross-sectional area of the nozzle is changeable. (23) The method according to (19), wherein the velocity of the fluid flow passing through the nozzle is subsonic. (24) The method according to (18), wherein the light beam substantially crosses the focal region from a lateral direction. (25) The method according to (18), wherein the light beam crosses the focal region from a substantially coaxial direction. (26) The method according to (18), wherein the focusing unit includes a unit that changes a distance between the focal area and the focusing unit. (27) The distance between the nozzle and the focal region irradiated by the light beam is at least three times the nozzle width.
The method according to (19), which is one-third. (28) The method according to (18), further including at least one means for moving the focusing means. (29) The method according to (18), wherein the particles to be detected are carried by at least one carrier fluid. (30) The method according to (29), wherein the at least one fluid is at least one gas. (31) The method according to (18), wherein the at least one light beam is a laser beam. (32) The method according to (18), wherein the at least one means for detecting the scattered light has at least one means for electrically calculating the scattered light. (33) The method of (18), further comprising removing at least a portion of the particles from the focal zone and the fluid conduit at and near the focal zone. (34) The method according to (33), wherein the removing means is a tube. (35) An apparatus for separating particles flowing in a fluid conduit, the nozzle having at least one focusing means for aerodynamically focusing the particles on a focal region, wherein the nozzle has a focal region. A device wherein the cross-sectional area is substantially smaller than the cross-sectional area of the focusing means, and comprising the focal zone and at least one means for removing the focused particles from the fluid conduit. (36) A method for separating particles flowing in a fluid conduit, the method comprising: (a) aerodynamically focusing particles separated by at least one focusing means into a focal zone, wherein the defocusing of the focal zone is performed. The area is smaller than the cross-sectional area of the focusing means, and (b) removing the separated particles from the focal zone and the fluid conduit. (37) The apparatus according to (16), further comprising at least one means for counting the particles in the focal zone. (38) The step of counting the particles in the focal region using at least one particle counting means, (3)
3) The method described above.

[0051]

The high efficiency particle detection provided by this new invention is suitable for many industrial applications such as SPC applications.

[Brief description of the drawings]

FIG. 1 illustrates a preferred flow nozzle of the present invention.

FIG. 2 is a schematic diagram of a preferred embodiment of the present invention, wherein the direction of travel of the light beam is substantially transverse to the fluid flow through the nozzle.

FIG. 3 is a schematic diagram of another embodiment of the present invention, wherein the direction of travel of the light beam is substantially co-axial with respect to the fluid flow through the nozzle.

FIG. 4 is a schematic diagram of another embodiment of the present invention illustrating an industrial process utilizing the present invention.

FIG. 5 is a schematic view of another embodiment of the present invention showing a dust collector for removing particles from a flowing stream.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Nozzle 12, 30 Housing 14, 16 Nozzle plate 11, 13 Flowing particle 15 Opening or outlet part 18 Light source 17 Iris diaphragm 19 Light detector 21 Lean area 22 Light beam 23 High concentration area 24 Light stop 26 Focus area 27 Nozzle axis 28 Collimator 29 Light receiving part 32, 34 Fluid conduit 37 Light beam axis 40 Processing unit 45 Processing chamber 50 Removal means 52 Pump 54 Via conduit 56 Tube 60 “Clean” carrier gas

────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Keanush Beizabi 2751, United States, P.O. Box 4751, Carly, North Carolina (56) References 4-98145 (JP, A) JP-A-63-214326 (JP, A) JP-A-56-46858 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01N 15/00 -15/14 G01N 21/41-21/61

Claims (38)

(57) [Claims] 1. A device for detecting the particles in vacuum, a fluid conduit substantially constant cross-sectional area of flowing particles, and at least one focusing means for focusing the particles in the focal region of the light beam A nozzle having at least one narrow light beam for illuminating the focal region; and at least one means for detecting scattered light of the particles illuminated by the light beam. Wherein the focusing means is fixed to the fluid conduit, and focuses the particles.
An aerodynamically sharp focusing device in said focal zone . Wherein said focusing means, in the fluid conduits, characterized in that fixed in the range of 90 to 135 degrees relative to the axial direction, the particles aerodynamically to the focal region, is sharply focused The apparatus of claim 1, wherein: 3. The apparatus of claim 2, wherein said nozzle is substantially axisymmetric. 4. The apparatus of claim 2, wherein said nozzle is substantially rectangular. 5. The apparatus of claim 2, wherein at least a portion of the cross-sectional area of the nozzle is adjustable. 6. The focusing means as claimed in claim 1, wherein said focusing means is fixed to said fluid conduit at an angle of 90 degrees with respect to an axial direction, and aerodynamically focuses said particles on said focal zone. 3. The apparatus according to 2. 7. The apparatus of claim 1, wherein said light beam traverses said focal zone from a substantially lateral direction. 8. The apparatus of claim 1, wherein the light beam traverses the focal zone from a substantially coaxial direction. 9. The apparatus according to claim 1, wherein said focusing means includes means capable of changing a distance between said focal zone and said focusing means. 10. The apparatus according to claim 2, wherein a distance between the nozzle and the focal region irradiated by the light beam is at least one-third of the nozzle width. 11. The apparatus according to claim 1, further comprising at least one means for moving said focusing means. 12. The apparatus of claim 1, wherein said particles to be detected are carried by at least one carrier fluid. 13. The apparatus of claim 12, wherein said at least one fluid is at least one gas. 14. The apparatus of claim 1, wherein said at least one light beam is a laser beam. 15. The apparatus according to claim 1, wherein said at least one means for detecting scattered light comprises at least one means for electronically calculating said scattered light. 16. The apparatus according to claim 16, further comprising at least one means for removing at least a portion of said particles from said focal zone and said fluid conduit at and near said focal zone.
The device according to claim 1. 17. The apparatus of claim 16, wherein said removal means is a tube. 18. The apparatus of claim 16, further comprising at least one means for counting said particles in said focal zone. 19. A method for detecting particles in vacuum, a fluid conduit substantially constant cross-sectional area of flow (a) particles, are fixed to the fluid conduit, and means for rapidly converging Causing the particles to flow through a nozzle having an aerodynamic focus on the focal region of the light beam ; and (b) irradiating the focal region with at least one narrow light beam, wherein the light beam is in the focal region. Causing the particles to be scattered by the particles, and (c) detecting the scattered light by the particles illuminated by the light beam and counting the number of particles in the focal zone detected in the detecting step. 20. The method according to claim 19 , wherein said focusing means is a sharply converging nozzle. 21. The method of claim 20 , wherein said nozzle is substantially axisymmetric. 22. The method of claim 20 , wherein said nozzle is substantially rectangular. 23. The method of claim 20 , wherein at least a portion of the cross-sectional area of the nozzle is variable. 24. The method of claim 20 , wherein the velocity of the fluid flow through the nozzle is subsonic. 25. The method of claim 19 , wherein said light beam traverses said focal zone from a substantially lateral direction. 26. The method of claim 19 , wherein the light beam traverses the focal zone from a substantially coaxial direction. 27. The method according to claim 19 , wherein said focusing means comprises means for changing a distance between said focal zone and said focusing means. 28. The method of claim 20 , wherein a distance between said nozzle and said focal zone illuminated by said light beam is at least one third of said nozzle width. 29. At least one of moving said focusing means
20. The method according to claim 19 , comprising two means. 30. The method of claim 19 , wherein said particles to be detected are carried by at least one carrier fluid. 31. The method of claim 30 , wherein said at least one fluid is at least one gas. 32. The method according to claim 19 , wherein said at least one light beam is a laser beam. 33. The method according to claim 19 , wherein said at least one means for detecting scattered light comprises at least one means for electrically calculating said scattered light. 34. The method of claim 19 , further comprising removing at least a portion of the particles from the focal zone and the fluid conduit at and near the focal zone. 35. The method according to claim 34 , wherein said removing means is a tube. 36. The method of claim 34 , further comprising counting said particles in said focal zone using at least one particle counting means. 37.] vacuum, a device for separating particles flowing in the flow body in the conduit, and the fluid conduit substantially constant cross-sectional area of flowing particles, is fixed to the fluid conduit, the particles A nozzle having at least one focusing means for focusing the light beam in a focal region; at least one means for illuminating the focal region; removing the focused particles from the focal region and the fluid conduit. And at least one means for removing the particles aerodynamically sharply focused in the focal region by the focusing means with high efficiency. 11. 38. A vacuum, a method for separating particles flowing in the flow body in the conduit, is fixed to the fluid conduit and, fluid conduit substantially constant cross-sectional area of flow (a) particles, rapidly Flowing the particles through a nozzle having means for focusing the particles, aerodynamically focusing the particles in the focal region of the light beam ; and (b) removing the separated particles from the focal region and the fluid conduit. how to.