Apparatus and method for monitoring particles in vacuum pipe

Abstract

To provide an in-vacuum pipe particle monitoring device and an in-vacuum pipe particle monitoring method for widely monitoring particles contained in gas flowing in a vacuum pipe.SOLUTION: A vacuum piping particle monitoring device (1) and a vacuum piping particle monitoring method, which are characterized by having a first pipe (6), a second pipe (2) through which a gas containing particles flows, an intersection (5) where the first pipe (6) and the second pipe (2) intersect, a light film forming means for forming a planar light film (13) inside the first pipe (6), and an observation means (21) for observing scattered light emitted by the particles, wherein the light film (13) is formed so as to cover at least 10% of the cross-sectional area of the second pipe (2) at the intersection (5), and the scattered light is emitted by the particles coming into contact with the surface of the light film at the intersection (5).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a particle monitoring device and a particle monitoring method for vacuum piping. [Background technology]

[0002] Currently, in response to the growing global demand for semiconductors and liquid crystal devices, Japan is focusing on the manufacture of these devices. Semiconductors and liquid crystal devices have been manufactured for a long time. During these manufacturing processes, particles can be generated unexpectedly within the manufacturing equipment, causing a decrease in the cleanliness of the equipment as the equipment continues to operate. If these particles accumulate in the product, it can lead to a decrease in product yield. Therefore, maintenance such as cleaning of the manufacturing equipment is required. However, because particles are too small to be observed with the naked eye, the criteria for determining whether the cleanliness of the manufacturing equipment has decreased due to particle accumulation have relied on, for example, the experience and intuition of the workers, or indirect indicators.

[0003] In such a situation, it may seem that increasing the frequency of maintenance would be the best way to maintain cleanliness, but naturally, the manufacturing equipment will not be able to contribute to product production during maintenance, and production efficiency will slow down. Therefore, it is not desirable to unnecessarily increase the frequency of maintenance in order to maintain cleanliness, and it is preferable to keep it to the minimum necessary.

[0004] Incidentally, it is rational and effective to set an appropriate maintenance timing for a manufacturing equipment by continuously monitoring in real time the occurrence of sudden particle generation within the manufacturing equipment and the degree of cleanliness caused by particles inside the manufacturing equipment, and by grasping the deterioration of cleanliness. If the manufacturing equipment operates with its internal pressure kept at atmospheric pressure, it is possible to monitor the deterioration of cleanliness with a general particle counter (for example, the particle counter described in Patent Document 1), but it is difficult to use such a particle counter in the case of a manufacturing equipment that operates with its internal pressure kept at a vacuum.

[0005] On the other hand, Patent Document 2 monitors particles at a cross section parallel to the flow direction in the pipe, as stated in claim 2: "A laser light irradiation unit that irradiates laser light into the exhaust pipe along a line segment connecting the center point of the cross section of the exhaust pipe and a central axis passing vertically through the center of the treatment chamber..." Therefore, when viewed from the flow direction, the area occupied by the laser light relative to the cross-sectional area of ​​the pipe is only the thickness of the laser light, and most particles pass through without coming into contact with the laser light and are not monitored. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-165771 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-59808 [Patent Document 3] Special Publication No. 2021-521433 Summary of the Invention [Problem to be solved by the invention]

[0007] If the ratio of the monitored area to the cross-sectional area of ​​the pipe is insufficient, as in Patent Documents 2 and 3, particles may flow without coming into contact with the laser light, which may prevent a sufficient understanding of the particle generation situation. In particular, if the number of particles generated is small, there is a risk that the particle generation event itself may be overlooked. Therefore, an object of the present invention is to provide a particle monitoring device and a particle monitoring method in vacuum pipes that can widely monitor particles contained in gas flowing through vacuum pipes. [Means for solving the problem]

[0008] The following describes an embodiment for solving the above problem. <First aspect> The first tube and a second tube through which the particle-containing gas flows; an intersection where the first pipe and the second pipe intersect; a light screen forming means for forming a planar light screen inside the first tube; and an observation means for observing scattered light emitted by the particles, At the intersection, the surface of the light film is formed over 10% or more of the cross-sectional area of ​​the second tube, The scattered light is emitted when the particles contact the surface of the light film at the intersection. A particle monitoring device for vacuum piping.

[0009] In this embodiment, the light film is formed over 10% or more of the cross-sectional area of ​​the second tube, so more particles flowing through the tube can be observed than with conventional observation methods, reducing observation loss.

[0010] <Second aspect> the observation means is located on the axis of the second pipe, and the observation direction of the observation means coincides with the axis of the second pipe; At the intersection, the plane of the light film and the observation direction by the observation means are perpendicular to each other. 1 is a first embodiment of a particle monitoring device for vacuum piping;

[0011] In this embodiment, the observation means is located on the axis of the second tube, and at the intersection, the surface of the light film and the observation direction by the observation means are perpendicular to each other, so that particles flowing through the second tube can be easily and clearly observed, and even if a large number of particles flow in at once, the scattered light can be observed individually as light pulses.

[0012] <Third aspect> The thickness of the light film is 3 mm or less; 1 is a first embodiment of a particle monitoring device for vacuum piping;

[0013] In this embodiment, the depth of field of the observation means can be narrow, and an optical system with a large effective aperture and a low F-number that can take in more light, i.e., a bright optical system, can be used. Furthermore, since the thickness of the light film is 3 mm or less, the possibility of overlapping scattered light from particles being captured is reduced.

[0014] <Fourth aspect> It has a light shielding plate, The light blocking plate is provided at a position other than the intersection of the first tube and not in contact with the light film. 1 is a first embodiment of a particle monitoring device for vacuum piping;

[0015] When a light film enters a vacuum pipe from the outside, some light diffusion may occur inside the pipe. This diffused light may brightly illuminate the inner surface of the pipe, which is the background from the observation means, and may cause a deterioration in the contrast between the scattered light from the particles and the background. By adopting this embodiment, such diffused light is blocked, making it possible to sufficiently darken the background, and it is possible to observe the weak scattered light from particles at the intersection with good contrast.

[0016] <Fifth aspect> A first embodiment of a particle monitoring device for vacuum piping, wherein the inner surface of the first pipe and the inner surface of the second pipe are black.

[0017] The inside of the tube can be illuminated by the light screen as well as diffusely reflected light, making the tube's inner surface bright. By making the inner surface of the tube have a low reflectivity as in this embodiment, diffuse reflection is suppressed and reflected light from areas that are the background when viewed from the observation means is also reduced, making it possible to observe even scattered light with low brightness at the intersection with good contrast.

[0018] <Sixth aspect> The first tube and a second tube through which the particle-containing gas flows; an intersection where the first pipe and the second pipe intersect; a light screen forming means for forming a planar light screen inside the first tube; a vacuum means for creating a vacuum state inside the first tube and inside the second tube; and an observation means for observing scattered light emitted by the particles, At the intersection, the surface of the light film is formed over 10% or more of the cross-sectional area of ​​the second tube, The scattered light is emitted by the particles contacting the surface of the light film at the intersection, using a particle monitoring device in a vacuum pipe, forming a light film inside the first tube; creating a vacuum inside the first tube and the second tube; flowing the gas through the second pipe; observing the scattered light emitted from the particles at the intersection with the observation means; A method for monitoring particles in a vacuum pipe.

[0019] This aspect provides the same effects as the first aspect. [Effects of the Invention]

[0020] According to the present invention, it is possible to monitor a wide range of particles contained in gas flowing through a vacuum pipe. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a diagram showing an example of installation of a particle monitoring device in a vacuum pipe according to the present invention. [Figure 2] 1 is a perspective view of a particle monitoring device for a vacuum pipe according to the present invention; [Figure 3] 1 is an explanatory diagram of an intersection of a vacuum pipe particle monitoring device according to the present invention. [Figure 4] 3 is a view taken along the line AA in FIG. 2, illustrating the formation of a light film. [Figure 5] 1A and 1B are diagrams showing the configuration of a light blocking plate according to the present invention. [Figure 6] 1A and 1B are diagrams showing the configuration of a light blocking plate according to the present invention. [Figure 7] FIG. 10 is a diagram showing an example of the arrangement of the light blocking plate 14. [Figure 8] FIG. 10 is a diagram showing an example of the arrangement of the light blocking plate 14. [Figure 9] FIG. 1 is a graph showing the relationship between the elapsed time from the start of observation and the number of particles (scattered light) counted. [Figure 10] This is an image of scattered light emitted by particles flowing through an intersection. The actual image is in color. [Figure 11] This is an image of scattered light emitted by particles flowing through an intersection. The actual image is in color. [Figure 12] This is an image of scattered light emitted by particles flowing through an intersection. The actual image is in color. [Figure 13] This is a graph showing that black electroless nickel plating treatment results in lower outgassing than black anodized aluminum treatment or Raydent (registered trademark) treatment. [Figure 14] This is a view of the intersection observed in the observation direction. [Figure 15] This is a view of the intersection observed in the observation direction. DETAILED DESCRIPTION OF THE INVENTION

[0022] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following description and drawings merely illustrate one embodiment of the present invention.

[0023] (First embodiment) A particle monitoring device 1 in a vacuum pipe according to a first embodiment of the present invention includes a first pipe 6, a second pipe 2 through which a gas containing particles flows, an intersection 5 where the first pipe 6 and the second pipe 2 intersect, a light screen forming means 11 that forms a planar light screen 13 inside the first pipe 6, and an observation means 21 that observes scattered light emitted by the particles, wherein the surface of the light screen 13 at the intersection 5 is formed over 10% or more of the cross-sectional area of ​​the second pipe 2, and the scattered light is emitted when the particles come into contact with the surface of the light screen at the intersection 5. A particle monitoring method in a vacuum pipe according to the present invention includes using the particle monitoring device 1 in a vacuum pipe to form the light screen 13 inside the first pipe 6, evacuating the insides of the first pipe 6 and the second pipe 2, flowing the gas through the second pipe 2, and observing the scattered light emitted from the particles at the intersection 5 with the observation means 21. Each component of the device will now be described. For convenience of explanation, in the vacuum pipe particle monitoring device 1 shown in Figure 2, the rightward direction of the axial center of the first pipe 6 on the paper surface is designated as the +y direction, and the leftward direction on the paper surface is designated as the -y direction. The upward direction of the axial center of the second pipe 2 on the paper surface is designated as the +z direction, and the downward direction on the paper surface is designated as the -z direction. Of the directions perpendicular to the axial center of the first pipe 6 and the axial center of the second pipe 2, the direction toward the front of the paper surface is designated as the +x direction, and the direction toward the back of the paper surface is designated as the -x direction. However, the axial center of the first pipe 6 does not necessarily have to be the y direction, and may be the z direction or the x direction. Similarly, the axial center of the second pipe 2 may be the x direction or the y direction. That is, the first pipe 6 may be oriented vertically or horizontally.

[0024] Referring to FIG. 1 , the vacuum piping particle monitoring device 1 according to this embodiment can be used to observe particles contained in a gas 31 flowing inside an exhaust pipe 39 attached to a vacuum chamber 40. One end of the exhaust pipe 39 is attached to the exhaust section of the vacuum chamber 40, and the other end can be attached to a gas supply unit 3 provided upstream of a second pipe 2 in the vacuum piping particle monitoring device 1. Gas flowing into the second pipe 2 from the gas supply unit 3 flows from the upstream side of the second pipe 2 through an intersection 5 to the downstream side of the second pipe 2, and reaches a gas discharge unit 4 connected to the downstream end of the second pipe 2, from which it is introduced into an exhaust system. The exhaust system is equipped with a vacuum means (e.g., a vacuum pump) that creates a vacuum inside the first pipe 6 and the second pipe 2. By operating the vacuum means, the vacuum piping particle monitoring device 1 and the vacuum chamber 40 can be adjusted to a negative pressure. If necessary, a turbomolecular pump or the like for increasing the degree of vacuum may be installed upstream of the particle monitoring device 1 in the vacuum pipe, i.e., between the vacuum chamber 40 and the particle monitoring device 1 in the vacuum pipe, or downstream of the particle monitoring device 1 in the vacuum pipe, i.e., between the particle monitoring device 1 in the vacuum pipe and the exhaust system. Here, the degree of vacuum in the vacuum pipe according to this embodiment may be, for example, low vacuum, medium vacuum, high vacuum, ultra-high vacuum, or extremely high vacuum, and a degree of vacuum higher than medium vacuum is particularly preferable. When the degree of vacuum is high, the main substances flowing through the vacuum pipe are particles.

[0025] In the vacuum chamber 40, for example, products such as liquid crystals and semiconductors are manufactured, and particles are generated as a result of the manufacturing process. The particles have an average diameter of, for example, 0.05 to 10 μm, and the vacuum piping particle monitoring device 1 according to this embodiment is used to observe these particles.

[0026] (Light film forming means) The light film 13 formed within the first tube 6 according to this embodiment is formed by irradiation from the light film forming means 11. The light film 13 may be configured to expand in the width direction as the light advances in the optical axis direction 13a, to narrow in the width direction as the light advances in the optical axis direction 13a, or to maintain a constant distance in the width direction as the light advances in the optical axis direction 13a. The irradiation area 15 of the light film 13 at the intersection 5 may be, for example, 10% or more of the cross-sectional area of ​​the second tube 2, preferably 30% or more, more preferably 50% or more, even more preferably 70% or more, and preferably 90% or more. If the irradiation area 15 is within the above range, it is easy to grasp the total amount of particles contained in the gas flowing through the second tube 2, even if the density of particles varies depending on the position within the tube. Furthermore, the thickness of the light film 13 is preferably 3 mm or less, more preferably 2 mm or less. The lower limit of the thickness of the light film 13 is not particularly limited, but is, for example, 10 μm.

[0027] The light source used in the light film forming means 11 according to this embodiment can have a wavelength of 350 to 1000 nm, and for example, a semiconductor laser with a wavelength of approximately 450 nm can be used as the light source.

[0028] The light film 13 formed within the first tube 6 can be adjusted so that the plane of the light film 13 at the intersection 5 is perpendicular to the observation direction 22 of the observation means 21. Even when a large number of particles instantaneously flow in, the scattered light from the particles is unlikely to overlap, and the scattered light can be observed individually as light pulses. Furthermore, when the plane of the light film 13 is perpendicular to the observation direction 22, the thickness at which the focus is achieved only needs to be equal to the thickness of the light film, and as a result, an optical system with a large effective aperture and a low F-number that can take in more light can be used, i.e., a bright optical system.

[0029] The light film 13 formed in the first tube 6 travels in an optical axis direction 13 a and is blocked by a beam trap 12 provided at the other end of the first tube 6 .

[0030] (Pipe 1) In the first tube 6 according to this embodiment, light from the light screen forming means 11 enters one end of the tube and is directed toward the other end, forming a light screen 13. The first tube 6 is preferably one that does not deform under vacuum conditions, and its tube wall is preferably opaque to light. A lid 9 is provided at one end of the first tube 6, and a lid 8 is provided at the other end. The inner diameter of the first tube 6 is not particularly limited, but may be, for example, 10 to 55 mm. The lids 8 and 9 are provided to prevent the flow of gas between the inside and outside of the first tube 6 and maintain a vacuum inside the first tube 6, and are preferably made of a material that allows light from the light screen forming means 11 to pass through. Therefore, examples of materials for the lids 8 and 9 include light-transmitting glass, particularly quartz glass. The first tube 6 is preferably a straight tube from the end where light enters from the light screen forming means 11 to the intersection 5.

[0031] (2nd tube) The second tube 2 according to this embodiment is, for example, a tube through which gas containing particles generated in a vacuum chamber flows. The second tube 2 according to this embodiment is preferably one that does not deform under vacuum conditions and has a tube wall that is opaque to light. A lid 7 is provided at the upstream end of the second tube 2. The second tube 2 has an intersection 5 where it intersects with the first tube 6, and a gas supply unit 3 is provided upstream of the intersection 5. The inner diameter of the second tube 2 is not particularly limited, but is, for example, 10 to 55 mm. The lid 7 is provided to prevent the flow of gas between the inside and outside of the second tube 2 and maintain a vacuum inside the second tube 2. It is preferable that the lid 7 be made of a light-transmitting material for monitoring scattered light generated at the intersection 5. Therefore, examples of the material for the lid 7 include light-transmitting glass, particularly quartz glass. The intersection 5 is formed by the first tube 6 and the second tube 2, allowing light and gas to pass from the first tube 6 to the second tube 2 and from the second tube 2 to the first tube 6.

[0032] Although the crossing angle between the first tube 6 and the second tube 2 according to this embodiment is not particularly limited, it is optimal to set it to approximately 90°. If the crossing angle is approximately 90°, when the observation means 21 is provided on the axis of the second tube 2, the observation direction 22 of the observation means 21 can be aligned with the axis of the second tube 2, making it possible to easily and clearly observe particles.

[0033] A tubular gas discharge section 4 may be provided at the downstream end of the second pipe 2, and a pipe for guiding the exhausted gas to an exhaust system may be connected to the downstream end of the gas discharge section 4.

[0034] On the other hand, a cross tube may be used instead of the intersection 5 of this embodiment. Let the four tube ends of the cross tube be tube end A, tube end B, tube end C, and tube end D in a clockwise direction. When using a cross tube, a total of four tubes are connected to each of the four tube ends of the cross tube. First, tube end A and tube end C, which are aligned in the same axial direction and positioned opposite each other, can be used as a group of gas tubes through which gas flows from the vacuum chamber 40. The remaining two tube ends B and D, which are aligned in the same axial direction and positioned opposite each other, can be used as a group of light film forming tubes through which the light film 13 is formed. On the other hand, the cross tube can also be configured such that tube end B extends in the -y direction and tube end D extends in the +y direction. In this configuration, tubes do not need to be connected to tube end B and tube end D, and covers 9 and 8 can be provided at tube end B and tube end D, respectively. In this case, it is preferable to arrange the tubes so that a light film 13 is formed from tube end B to tube end D, and the particle-containing gas flows from tube end A to tube end C. The diameters of tube end B and tube end D may be larger than the diameters of tube end A and tube end C, or the diameters of tube end A, tube end B, tube end C, and tube end D may all be the same. In particular, since light film 13 is formed at tube end B and tube end D, it is preferable to make the diameters of tube end B and tube end D larger than the diameters of tube end A and tube end C, as this forms a relatively wide light film 13 and allows the flow of particle-containing gas to be observed over a wide area. Similarly, it is also preferable to make the diameter of the first tube 6 larger than the diameter of the second tube 2.

[0035] (Method of observation) The observation means 21 according to this embodiment comes into contact with the light film 13 at the intersection 5 and observes the scattered light emitted by the passing particles. When the section from the upstream end of the second tube 2 to the intersection 5 is a straight tube, the observation means 21 is preferably provided outside the upstream end of the second tube 2. However, the observation means 21 can also be provided outside the downstream end of the second tube 2. In this case, the direction from the downstream end of the second tube 2 toward the intersection 5 is preferably the observation direction 22.

[0036] On the other hand, when the observation means 21 is located on the axis of the second tube 2, the light screen 13 formed in the first tube 6 should be adjusted so that the plane of the light screen and the observation direction 22 by the observation means 21 are perpendicular to each other at the intersection 5. Scattered light generated by particles passing through the light screen 13 can be captured over a wide range.

[0037] Patent Document 3 discloses a technology related to particle sensors. In this technology, the device is designed to detect scattered light from a direction parallel to the plane of the laser sheet emitted from the light source. The relationship between the gas flow direction, the plane of the light film 13, and the observation direction 22 differs from that of the particle monitoring device 1 in vacuum piping according to the present embodiment. With the technology of Patent Document 3, when a large number of particles flow in instantaneously, the scattered light from the particles overlaps and is detected as a single light pulse, which raises concerns about detection loss. Furthermore, the detector is adjusted to focus parallel to the plane of the laser sheet, which has a predetermined width, i.e., the depth of field is adjusted to be large. This results in a detector with a large F-number and a relatively dark optical system, which may make it difficult to detect weak scattered light emitted by minute particles.

[0038] On the other hand, in the vacuum pipe particle monitoring device 1 according to this embodiment, the surface of the light film 13 is formed over 10% or more of the cross-sectional area of ​​the second pipe 2 at the intersection 5. Here, if the thickness of the light film 13 is 3 mm or less and the surface of the light film 13 is perpendicular to the observation direction 22 of the observation means 21 at the intersection 5, the depth of field of the observation means 21 can be relatively narrow, a bright optical system can be used, and a particle group can be captured as a wide two-dimensional image. Therefore, even if a large number of particles flow simultaneously over a wide area, they can be observed with as little loss as possible. Furthermore, even weak scattered light emitted by minute particles can be observed.

[0039] The observation means 21 is not particularly limited, but for example, a CCD camera, a CMOS camera, or the like can be used as appropriate.

[0040] The processing such as extraction, counting, and classification of the particles observed by the observation means 21 can be performed by known image processing such as labeling.

[0041] (Second embodiment) The particle monitoring device 1 in a vacuum pipe according to the second embodiment of the present invention has the same basic configuration as the monitoring device of the first embodiment, but differs from the first embodiment in that a light shielding plate 14 is provided in the first pipe 6. The light shielding plate 14 is preferably provided at a location other than the intersection 5 of the first pipe 6 and not in contact with the light screen 13. The particle monitoring device 1 in a vacuum pipe is configured such that covers 8 and 9 are provided at both ends of the first pipe 6 to maintain a vacuum inside the pipe, blocking the flow of gas from both ends of the first pipe 6. When a light screen is introduced into the first pipe 6 from the outside, the light passes through the light-transmitting cover 9. However, depending on the material of the cover 9, some light diffusion occurs as the light passes through the cover 9. This diffused light may brightly illuminate the inner surface of the pipe, which is the background when viewed from the observation means 21, thereby reducing the contrast between the scattered light from the particles and the background. In the vacuum pipe particle monitoring device 1 according to the second embodiment, such diffused light is blocked by the light shielding plate 14, making it possible to make the background sufficiently dark and to observe the scattered light of weak particles at the intersection with good contrast. Figures 14 and 15 are views of the intersection 5 in the second pipe 2 observed in the observation direction 22, with Figure 14 showing the case where the light shielding plate 14 is not installed and Figure 15 showing the case where the light shielding plate is installed.

[0042] The light-shielding plate 14 may be a light-shielding plate, such as a stainless steel plate, preferably a blackened stainless steel plate, more preferably a blackened electroless nickel-plated stainless steel plate.

[0043] The light blocking plate 14 of this embodiment can block diffused light by being provided with a plate surface substantially perpendicular to the optical axis direction 13a of the light screen 13. The light blocking plate 14 may have, for example, an opening slightly larger than the width and thickness of the light screen 13 so that the light screen 13 can pass through (see FIG. 5), or a substantially semicircular plate having an arc portion formed to contact the inner peripheral surface of the first tube 6 without any gap, and a chord portion 14c (see FIG. 6). When the light blocking plate 14 is provided on the first tube 6, it is preferable that the chord portion 14c of the substantially semicircular plate be parallel to the surface of the light screen 13 so as not to contact the light screen 13.

[0044] The light-shielding plate 14 only needs to be approximately 1 mm thick, and the chord portion 14c on one side may have a chamfered portion 14b, which is chamfered along the chord. If a light screen 13 is formed on the first tube 6 equipped with the light-shielding plate 14, the chord portion 14c of the light-shielding plate 14 may be shining due to light reflection, making it difficult to observe particles. A light-shielding plate 14 with a chamfered portion 14b can make the intersection 5 darker, which is advantageous for particle observation. The chamfering angle α is not particularly limited, but it is preferable that the chord portion 14c on one side of the light-shielding plate 14 be approximately 45° with respect to the thickness direction, for example. The light-shielding plate 14 may be installed so that the other side without the chamfered portion 14b faces the intersection 5.

[0045] 3, 7, and 8, the light shielding plate 14 may be provided in multiple pieces, such as a first light shielding plate 141, a second light shielding plate 142, a third light shielding plate 143, and a fourth light shielding plate 144. In the first tube 6, if the side where the light screen 13 from the light screen forming means 11 enters is defined as the upstream side of the light screen and the side where the beam trap 12 is located is defined as the downstream side of the light screen, the first light shielding plate 141 of this embodiment may be disposed, for example, at a distance L1 from the upstream corner 6a of the first tube 6 at the intersection 5, preferably 0 to 10 mm, more preferably 0 to 5 mm, and even more preferably 0 mm (i.e., the upstream corner 6a of the first tube 6 at the intersection 5), upstream of the first tube 6, so that the plate surface is approximately perpendicular to the optical axis direction 13a of the light screen 13. The corners 6a, 6b, and so on are the joints between the first tube 6 and the second tube 2. The substantially semicircular first light-shielding plate 141 can be provided in the space 17 inside the first tube 6, on the far side of the formed light film 13, when the first tube 6 is viewed from the observation means 21 in the observation direction 22 (-z direction). A second light-shielding plate 142 can be provided upstream of the first tube 6 from the first light-shielding plate 141, with a distance L2 between them. The distance L2 may be, for example, greater than 0 mm, more preferably 10 mm or greater, and suitably 20 mm or greater. The second light-shielding plate 142 can be provided in the space 16 inside the first tube 6, on the near side of the formed light film 13, when the first tube 6 is viewed from the observation means 21 in the observation direction 22 (-z direction). This arrangement can block light diffused into the far side space 17 and the near side space 16 in the first tube 6, making it easier to observe particles.

[0046] In addition to the first and second light-shielding plates 141 and 142, a third and fourth light-shielding plate 143 and 144 may also be provided downstream of the intersection 5 in the first tube 6. The third light-shielding plate 143 of this embodiment may be disposed, for example, at a distance L3 from a downstream corner 6b of the first tube 6 at the intersection 5 to the downstream side of the first tube 6, preferably 0 to 10 mm, more preferably 0 to 5 mm, and even more preferably 0 mm (i.e., from the downstream corner 6b of the first tube 6 at the intersection 5), so that the plate surface is approximately perpendicular to the optical axis direction 13a of the light film 13. The approximately semicircular third light-shielding plate 143 may be provided in a space 17 inside the first tube 6 that is deeper than the formed light film 13 when the first tube 6 is viewed from the observation means 21 in the observation direction 22 (-z direction). Furthermore, a fourth light-shielding plate 144 can be provided downstream of the first tube 6 at a distance L4 from the third light-shielding plate 143. The distance L4 may be, for example, greater than 0 mm, more preferably 10 mm or greater, and preferably 20 mm or greater. Here, the fourth light-shielding plate 144 can be provided in the space 16 in front of the formed light film 13 within the first tube 6 when the first tube 6 is viewed in the observation direction 22 (-z direction) from the observation means 21. This arrangement can block light diffused into the space 17 at the back side of the first tube 6 and light diffused into the space 16 at the front side, making it easier to observe particles.

[0047] When the first light-shielding plate 141 is installed, it is sufficient that the first light-shielding plate 141 is spaced apart from the light film 13 by a distance L5. Similarly, when the second light-shielding plate 142, the third light-shielding plate 143, and the fourth light-shielding plate 144 are installed, it is sufficient that the second light-shielding plate 142, the third light-shielding plate 143, and the fourth light-shielding plate 144 are each spaced apart from the light film 13 by a distance L5. The distance L5 is, for example, 2 mm or less, preferably 1.5 mm or less, more preferably 1 mm or less, and suitably 0.5 mm or less.

[0048] The light shielding plate 14 is arranged so as not to come into contact with the light screen 13, and specifically, in the case where the axial direction of the first tube 6 is the y direction, the optical axis direction 13a of the light screen 13 is the y direction, the surface of the light screen 13 is the xy plane, and the observation direction 22 is the -z direction, when the first light shielding plate 141 is provided in the back space 17, it is sufficient to arrange it so that the chord portion 14c of the first light shielding plate 141 is parallel to the surface of the light screen 13. Similarly, the second light shielding plate 142, the third light shielding plate 143, and the fourth light shielding plate 144 are each arranged so that the chord portion 14c of each of the second light shielding plate 142, the third light shielding plate 143, and the fourth light shielding plate 144 is parallel to the surface of the light screen 13.

[0049] The shape of the edge of the arc portion of the light blocking plate 14 should preferably be matched to the shape of a cross section when the first tube 6 is cut in the circumferential direction. In this way, the edge of the arc portion of the light blocking plate 14 can be fitted to the inner peripheral surface of the first tube 6, and the arc portion and the inner peripheral surface can be closed so that there is no gap between them, thereby fixing the light blocking plate 14 to the first tube 6.

[0050] (Third embodiment) When observing particles in a vacuum, light may be diffused or scattered inside the pipe, brightening the background and making it difficult to observe with good contrast. Therefore, a particle monitoring device 1 for vacuum pipes according to a third embodiment of the present invention has the same basic configuration as the monitoring device of the first embodiment, but one or both of the inner surfaces of the first pipe 6 and the second pipe 2 are black. Blackening the inner surfaces of the pipes reduces light reflection and diffusion inside the pipes, improving the contrast between the scattered light image of particles contained in the gas flowing through the second pipe 2 and the surrounding background. Blackening can be achieved, for example, by black anodizing or Raydent (registered trademark) treatment. However, even with a black inner surface, outgassing and particles may still be generated. These particles may backflow inside the pipe and contaminate manufactured products during, before, or after film formation and other processes in manufacturing equipment. Therefore, it is more preferable to subject the inner surface of the pipe to black electroless nickel plating. Black electroless nickel plating not only enables good contrast observation but also suppresses the generation of outgassing and particles, which are likely to occur when a vacuum is created.

[0051] Figure 13 is a graph plotting the outgassing rate versus evacuation time for tubes whose inner surfaces had undergone various treatments. Reference numeral 61 denotes a tube treated with black anodizing, reference numeral 62 denotes a tube treated with Raydent (registered trademark) (first treatment), reference numeral 63 denotes a tube treated with Raydent (registered trademark) (second treatment), reference numeral 64 denotes a tube treated with black electroless nickel plating, reference numeral 65 denotes a tube made of SUS304L that had been treated with glass bead blasting (GBB), and reference numeral 66 denotes a tube made of SUS304L that had been treated with electrolytic polishing. Figure 13 shows that black electroless nickel plating suppresses outgassing more than black anodizing or Raydent (registered trademark) treatments.

[0052] One or both of the inner surfaces of the first tube 6 and the second tube 2 can be blackened by plating (hot-dip plating, vacuum plating, electroless plating, electrolytic plating, etc.). Examples of electrolytic methods include black electrolytic chrome plating, black electrolytic nickel plating, black electrolytic tin alloy plating, and black electrodeposition coating. On the other hand, examples of methods for obtaining a black coating by electroless nickel plating include black electroless nickel-phosphorus-zinc alloy plating, black electroless pure nickel plating, and black electroless nickel-tin plating. In particular, black electroless nickel-plated tubes are preferred because, as described above, they can suppress light reflection and diffusion and the generation of outgassing and particles.

[0053] It is also desirable to provide the light blocking plate 14 on the first tube 6 and to color one or both of the inner surface of the first tube 6 and the inner surface of the second tube 2 black.

[0054] The vacuum piping particle monitoring device 1 according to the third embodiment may also be combined with the second embodiment to have a configuration in which the light blocking plate 14 is provided in the first pipe 6.

[0055] (others) Regarding the drawings, the light film 13 shown in Fig. 2 is formed inside the first tube 6 and is not visible from the outside, but is shown for the sake of explanation. The first tube 6 and the second tube 2 in Fig. 3 are cylindrical, but are shown in cross section for the sake of explanation. [Example]

[0056] A particle observation test was carried out using this embodiment. The procedure was as follows. For the particle monitoring device in vacuum piping according to this embodiment, a turbo molecular pump was connected to the vacuum chamber, and its exhaust was connected to the gas supply unit of the particle monitoring device in vacuum piping. The gas exhaust unit was connected to a dry pump, and the pump was started to reduce the air pressure inside the tube of the particle monitoring device in vacuum piping to 1 Pa or less. A laser sheet light source with a wavelength of 450 nm was used as the light screen forming means. A CMOS camera was used as the observation means, and the frame rate was set to 60 FPS (frames per second). NW25 standard tubes with a diameter of 23 mm were used for the first tube in which the light screen of the particle monitoring device in vacuum piping was formed and the second tube through which gas flows, and the diameter of the intersection was 23 mm. The cross-sectional area (at the intersection) of the second tube through which gas flows was 415 mm. 2 The area of ​​the light film at the intersection is 313 mm 2 At the intersection, the light film was formed so that the surface of the light film was 75.4% of the cross-sectional area of ​​the intersection.

[0057] The liquid crystal film-forming device in the vacuum chamber was started and stopped to generate particles, and the generated particles were imaged over time using an observation means as they passed through the intersection, and the number of particles was counted. The results are shown in Figures 9 to 12. A characteristic particle peak 41 was observed 120 seconds after the start of observation. Figure 10 shows the appearance of peak 41 of the observed particle (observed particle 54). Furthermore, a characteristic particle peak 42 was observed 300 seconds after the start of observation. Figure 11 shows the appearance of peak 42 of observed particle 54. Furthermore, a characteristic particle peak 43 was observed 1,350 seconds after the start of observation. Figure 12 shows the appearance of peak 43 of observed particle 54.

[0058] The observed particles 54 varied in size, with peak 41 consisting mainly of small particles with diameters of 0.5 μm or more and less than 1 μm, and medium-sized particles with diameters of 1 μm or more and less than 5 μm. Peak 42 consisted of small and medium-sized particles, as well as large particles with diameters of 5 μm or more. In particular, in Figure 11, the particle density was dense on the left side of the page within the observed range, and sparse on the right side, revealing a density difference. [Industrial Applicability]

[0059] The present invention is applicable to gas flow visualization and particle image velocimetry, etc. It is applicable to all fields where particle flow is of interest, such as semiconductors, liquid crystals, pharmaceuticals, food, medicine, automobiles, films, and metal processing. [Explanation of symbols]

[0060] 1. Particle monitoring device for vacuum pipes 2 2nd pipe 3 Gas supply section 4 Gas exhaust section 5 Intersection 6 1st pipe 7 Lid 8 Lid 9 Lid 11 Photo film forming means 13 Light film 13a Optical axis direction 14 Shade 14a opening 14b Chamfered part 15 Irradiation area 21 Observation methods 22 Observation direction 31 Gas 40 Vacuum Chamber 41 Peak 42 Peak 43 Peak 51 Number of small particles 52 Number of medium-sized particles 53 Number of large particles 54 Observation Particles

Claims

1. A first tube; a second pipe through which the particle-laden gas flows; an intersection portion where the first pipe and the second pipe intersect; a light screen forming means for forming a planar light screen inside the first tube; a vacuum means for creating a vacuum state inside the first tube and the second tube; and an observation means for observing scattered light emitted by the particles, At the intersection, the surface of the light film is formed over 10% or more of the cross-sectional area of ​​the second tube, The scattered light is emitted when the particles contact the surface of the light film at the intersection. A particle monitoring device for vacuum piping.

2. the observation means is located on the axis of the second pipe, and the observation direction of the observation means coincides with the axis of the second pipe; At the intersection, the plane of the light film and the observation direction by the observation means are perpendicular to each other. The vacuum pipe particle monitoring device according to claim 1 .

3. The thickness of the light film is 3 mm or less. The vacuum pipe particle monitoring device according to claim 1 .

4. It has a light shielding plate, The light blocking plate is provided at a position other than the intersection of the first tube and not in contact with the light film. The vacuum pipe particle monitoring device according to claim 1 .

5. the inner surface of the first tube and the inner surface of the second tube are black; The vacuum pipe particle monitoring device according to claim 1 .

6. A first tube; a second pipe through which the particle-laden gas flows; an intersection portion where the first pipe and the second pipe intersect; a light screen forming means for forming a planar light screen inside the first tube; a vacuum means for creating a vacuum state inside the first tube and the second tube; and an observation means for observing scattered light emitted by the particles, At the intersection, the surface of the light film is formed over 10% or more of the cross-sectional area of ​​the second tube, The scattered light is emitted by the particles contacting the surface of the light film at the intersection, using a particle monitoring device in a vacuum pipe, forming a light film inside the first tube; creating a vacuum inside the first tube and the second tube; flowing the gas through the second pipe; observing the scattered light emitted from the particles at the intersection with the observation means; A method for monitoring particles in a vacuum pipe.

Images