Vacuum piping particle monitoring device and vacuum piping particle monitoring method

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 in a vacuum pipe and a particle monitoring method in a vacuum pipe.

Background Art

[0002] Currently, in response to the increasing global demand for semiconductors and liquid crystal devices, efforts are being made in Japan to manufacture these devices. The production of semiconductors and liquid crystals has been carried out conventionally. In these manufacturing processes, particles may suddenly be generated in the manufacturing apparatus, and as the operation continues, the cleanliness inside the apparatus decreases. When the generated particles accumulate on the product, there is a problem of causing a decrease in the yield of the product. Therefore, the manufacturing apparatus has to be maintained by cleaning or the like. However, since particles are very small and cannot be observed with the naked eye, the criteria for determining whether the cleanliness has decreased due to the accumulation of particles in the manufacturing apparatus are based on, for example, the experience and intuition of workers, indirect indicators, and the like.

[0003] In such a situation, if one tries to maintain the cleanliness as much as possible, it may seem that the number of maintenance operations should be increased. However, during maintenance, the manufacturing apparatus naturally cannot contribute to the production of products, and the production efficiency is dulled. Therefore, it is not desirable to increase the number of maintenance operations unnecessarily in order to maintain the cleanliness, and it is desirable to keep it to the minimum necessary number.

[0004] By the way, the appropriate maintenance timing of the manufacturing apparatus is to monitor the sudden generation of particles in the manufacturing apparatus and the degree of cleanliness due to the particles inside the manufacturing apparatus in real time and continuously, and it is reasonable and effective to set it after grasping the decrease in cleanliness. If the manufacturing apparatus operates with its internal pressure at atmospheric pressure, the decrease in cleanliness can be monitored with a general particle counter (for example, the particle counter described in Patent Document 1). However, in the case of a manufacturing apparatus that operates with its internal pressure in a vacuum state, it is difficult to use such a particle counter.

[0005] On the other hand, Patent Document 2, as stated in claim 2, includes "a laser beam 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 pre-treatment chamber, ...", which monitors particles in a cross section parallel to the flow direction inside the pipe. Therefore, when viewed from the flow direction, the area occupied by the laser beam relative to the cross-sectional area inside the pipe is only the thickness of the laser beam, and most particles pass through without coming into contact with the laser beam and are not monitored. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-165771 [Patent Document 2] Japanese Patent Publication No. 2001-59808 [Patent Document 3] Special Publication No. 2021-521433 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] As described in Patent Documents 2 and 3, if the ratio of the monitored area to the cross-sectional area of ​​the pipe is insufficient, there is a risk that the particle generation situation may not be adequately understood if particles flow without coming into contact with the laser light. In particular, if the number of generated particles is small, there is a risk of missing the particle generation event itself. Therefore, the problem to be solved by the present invention is to provide a vacuum pipe particle monitoring device and a vacuum pipe particle monitoring method that broadly monitor particles contained in the gas flowing through the vacuum pipe. [Means for solving the problem]

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

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

[0010] <Second aspect> The observation means is located on the axis of the second tube, and the observation direction of the observation means coincides with the axis of the second tube. At the aforementioned intersection, the surface of the optical film and the observation direction by the observation means are perpendicular to each other. A particle monitoring apparatus in a vacuum pipe according to a first embodiment.

[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. Therefore, particles flowing through the second tube can be easily and clearly observed, and even when a large number of particles flow instantaneously, the scattered light can be observed individually as light pulses.

[0012] <Third aspect> The thickness of the aforementioned optical film is 3 mm or less. A particle monitoring apparatus in a vacuum pipe according to a first embodiment.

[0013] In this aspect, the depth of field of the observation means may be shallow, and an optical system with a low F-number that has a large effective aperture and can capture more light, so-called a bright optical system, can be used. Further, since the thickness of the light film is 3 mm or less, the possibility that the scattered light of the particles overlaps and is imaged is reduced.

[0014] <Fourth Aspect> having a light shielding plate, where the light shielding plate is provided at a position other than the intersection portion in the first tube and not in contact with the light film. The particle monitoring device in the vacuum pipe of the first aspect.

[0015] When a light film enters the vacuum pipe from the outside, some light diffusion may be caused inside the pipe. The diffused light brightly illuminates the inner surface of the pipe, which serves as the background as seen from the observation means, and may cause deterioration of the contrast between the scattered light from the particles and the background. By adopting this aspect, such diffused light is shielded, and the background can be made sufficiently dark, so that the scattered light of weak particles at the intersection can be observed with good contrast.

[0016] <Fifth Aspect> The particle monitoring device in the vacuum pipe of the first aspect, wherein the inner surface of the first tube and the inner surface of the second tube are black.

[0017] The inside of the pipe may be illuminated by the light film and other diffusely reflected light, making the inner surface of the pipe bright. By making the inner surface of the pipe have a low reflectivity as in this aspect, diffuse reflection is suppressed, and the reflected light from the region that serves as the background as seen from the observation means is also reduced, so that even the scattered light with low luminance at the intersection can be observed with good contrast.

[0018] <Sixth Aspect> a first tube, a second tube through which a gas containing particles flows, an intersection where the first tube and the second tube intersect, a light film forming means for forming a planar light film inside the first tube, A vacuum means for creating a vacuum inside the first tube and the second tube, The system includes an observation means for observing the scattered light emitted by the aforementioned particles, At the intersection, the surface of the optical film is formed over 10% or more of the cross-sectional area of ​​the second tube. Using a particle monitoring device in a vacuum pipe, the scattered light is emitted when the particles come into contact with the surface of the optical film at the intersection. A light film is formed inside the first tube, The inside of the first tube and the inside of the second tube are made into a vacuum state. The gas is passed through the second pipe, The scattered light emitted from the particles at the intersection is observed by the observation means. A method for monitoring particles in a vacuum pipe, characterized by the following features.

[0019] In this embodiment, the same effects as in the first embodiment are achieved. [Effects of the Invention]

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

[0021] [Figure 1] This figure shows an example of the installation of a particle monitoring device in vacuum piping according to the present invention. [Figure 2] This is a perspective view of the vacuum piping particle monitoring device according to the present invention. [Figure 3] This is an explanatory diagram of the intersection of the vacuum piping particle monitoring device according to the present invention. [Figure 4] This is a view along the arrow AA in Figure 2, and is an explanatory diagram illustrating the formation process of the photofilm. [Figure 5] This figure shows an embodiment of a light-shielding plate according to the present invention. [Figure 6] This figure shows an embodiment of a light-shielding plate according to the present invention. [Figure 7] This diagram shows an example of the arrangement of the light-shielding plates 14. [Figure 8] This diagram shows an example of the arrangement of the light-shielding plates 14. [Figure 9] This figure shows the relationship between the elapsed time since the start of observation and the count of particles (scattered light). [Figure 10] This is a diagram showing the scattered light emitted by particles flowing through an intersection. The actual image is in color. [Figure 11] This is a diagram showing the scattered light emitted by particles flowing through an intersection. The actual image is in color. [Figure 12] This is a diagram showing the scattered light emitted by particles flowing through an intersection. The actual image is in color. [Figure 13] This diagram shows that products treated with black electroless nickel plating produce less outgassing than those treated with black anodizing or Raydent®. [Figure 14] This is a diagram showing the intersection as observed in the direction of observation. [Figure 15] This is a diagram showing the intersection as observed in the direction of observation. [Modes for carrying out the invention]

[0022] The following describes in detail embodiments for carrying out the present invention. Note that the following description and drawings are merely illustrations of one embodiment of the present invention.

[0023] (First Embodiment) A vacuum piping particle monitoring device 1 according to the first embodiment of the present invention comprises 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 11 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. 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, and the scattered light is emitted when the particles come into contact with the surface of the light film at the intersection 5. Furthermore, a vacuum piping particle monitoring method according to the present invention is characterized by using the vacuum piping particle monitoring device 1 to form a light film 13 inside the first pipe 6, creating a vacuum inside 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 using the observation means 21. The various parts of the device will be described below. For the sake of explanation, in the vacuum piping particle monitoring device 1 shown in Figure 2, the direction to the right of the plane of the first pipe 6 is defined as the +y direction, and the direction to the left of the plane of the plane as the -y direction. The direction upwards of the plane of the second pipe 2 is defined as the +z direction, and the direction downwards is defined as the -z direction. The direction perpendicular to the axial directions of the first pipe 6 and the axial directions of the second pipe 2 is defined as the direction towards the front of the plane as the +x direction, and the direction backwards as the -x direction. However, the axial direction of the first pipe 6 does not necessarily have to be the y direction; it may be the z direction or the x direction, and similarly, the axial direction of the second pipe 2 may be the x direction or the y direction. In other words, the first pipe 6 may be vertical or horizontal.

[0024] The vacuum piping particle monitoring device 1 according to this embodiment can be described with reference to Figure 1 and can be used to observe particles contained in a gas 31 flowing through 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 section 3 provided on the upstream side of the second pipe 2 in the vacuum piping particle monitoring device 1. The gas flowing into the second pipe 2 from the gas supply section 3 flows from the upstream side of the second pipe 2 through the intersection section 5 to the downstream side of the second pipe 2, reaches a gas discharge section 4 connected to the downstream end of the second pipe 2, and is introduced into the exhaust system from the gas discharge section 4. The exhaust system is equipped with a vacuum means (for example, a vacuum pump) that creates a vacuum inside the first pipe 6 and the second pipe 2, and by operating the vacuum means, the vacuum piping particle monitoring device 1 and the vacuum chamber 40 can be adjusted to negative pressure. If necessary, a turbomolecular pump or the like may be installed upstream of the vacuum piping particle monitoring device 1, i.e., between the vacuum chamber 40 and the vacuum piping particle monitoring device 1, or downstream of the vacuum piping particle monitoring device 1, i.e., between the vacuum piping particle monitoring device 1 and the exhaust system, to increase the vacuum level. Here, the vacuum level in the vacuum piping according to this embodiment may be, for example, low vacuum, medium vacuum, high vacuum, ultra-high vacuum, or extremely high vacuum, and is particularly preferably higher than medium vacuum. When the vacuum level is high, the main material flowing through the vacuum piping is particles.

[0025] In the vacuum chamber 40, products such as liquid crystals and semiconductors are manufactured, and particles are generated as a result of the manufacturing process. These 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 observes these particles.

[0026] (Light film forming means) The optical film 13 formed inside the first tube 6 according to this embodiment is formed by irradiation from the optical film forming means 11. The optical film 13 may be in a form that expands in the width direction as the light travels along the optical axis 13a, or in a form that narrows in the width direction as the light travels along the optical axis 13a, or in a form that travels along the optical axis 13a while maintaining a constant distance in the width direction. The irradiation area 15 of the optical 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 suitable if 90% or more. If the irradiation area 15 is within the above range, it is easy to grasp the total amount of particles even if there are density differences depending on the position in the tube of the particles contained in the gas flowing through the second tube 2. The thickness of the optical film 13 may be preferably 3 mm or less, more preferably 2 mm or less. The lower limit of the thickness of the optical film 13 is not particularly limited, but for example it is 10 μm.

[0027] The light source used in the photofilm 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 optical film 13 formed inside the first tube 6 should be adjusted so that the surface of the optical film 13 at the intersection 5 is perpendicular to the observation direction 22 by the observation means 21. Even when many particles flow instantaneously, the scattered light from the particles is less likely to overlap, and the scattered light can be observed individually as light pulses. Furthermore, if the surface of the optical film 13 and the observation direction 22 are perpendicular, the thickness at which focus is achieved only needs to be equal to the thickness of the optical film, and as a result, a low F-number optical system, a so-called bright optical system, can be used, which has a large effective aperture and can capture more light.

[0029] The optical film 13 formed on the first tube 6 advances in the optical axis direction 13a and is shielded by the 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 photofilm forming means 11 enters from one end of the tube and is irradiated toward the other end to form a photofilm 13. The first tube 6 is preferably one that does not deform under vacuum conditions, and it is desirable that the tube wall does not transmit 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 for example, it is 10 to 55 mm. The lids 8 and 9 are provided to prevent the flow of gas inside and outside the first tube 6 and to maintain a vacuum inside the first tube 6, and it is preferable that they be made of a material that allows light from the photofilm forming means 11 to pass through. Therefore, the material of the lids 8 and 9 can be, for example, light-transmitting glass, especially quartz glass. On the other hand, it is preferable that the first tube 6 is a straight tube type from the end into which light enters from the photofilm forming means 11 to the intersection 5.

[0031] (2nd tube) The second tube 2 in this embodiment is, for example, a tube through which a gas containing particles generated in a vacuum chamber flows. The second tube 2 in this embodiment is preferably one that does not deform under vacuum conditions, and it is desirable that the tube wall does not transmit light. A cover 7 is provided at the upstream end of the second tube 2. The second tube 2 has an intersection 5 that intersects with the first tube 6, and a gas supply section 3 is provided upstream of the intersection 5. The inner diameter of the second tube 2 is not particularly limited, but for example, it is 10 to 55 mm. The cover 7 is provided to prevent the flow of gas inside and outside the second tube 2 and to maintain a vacuum inside the second tube 2, and it is preferable that it be made of a material that can transmit light in order to monitor scattered light generated at the intersection 5. Therefore, the material of the cover 7 can be, for example, light-transmitting glass, especially quartz glass. The intersection 5 is formed by the first tube 6 and the second tube 2, and light and gas can move back and forth from the first tube 6 to the second tube 2, or from the second tube 2 to the first tube 6.

[0032] The intersection angle between the first tube 6 and the second tube 2 in this embodiment is not particularly limited, but approximately 90° is optimal. If the intersection angle is approximately 90°, when the observation means 21 is placed on the axis of the second tube 2, the observation direction 22 by the observation means 21 can be aligned with the axis direction of the second tube 2, allowing for easy and clear observation of particles.

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

[0034] On the other hand, instead of the intersection 5 in this embodiment, a cross pipe may be used. If the four ends of the cross pipe are designated as end A, end B, end C, and end D in a clockwise direction, then when using a cross pipe, a total of four pipes can be connected to each of the four ends of the cross pipe. First, end A and end C, whose axes coincide and are in an opposing position, can be made into a group of gas pipes through which the gas flowing from the vacuum chamber 40 passes, and the remaining two end B and end D, whose axes coincide and are in an opposing position, can be made into a group of photofilm forming pipes through which the photofilm 13 is formed. On the other hand, the cross pipe can also be configured such that end B extends in the -y direction and end D extends in the +y direction. In this configuration, it is not necessary to connect pipes to end B and end D, and it is preferable to provide covers 9 and 8 at the respective ends of end B and end D. In this case, it is preferable to arrange the pipes so that the optical film 13 is formed from pipe end B to pipe end D, and the gas containing particles flows from pipe end A to pipe end C. The diameters of pipe end B and pipe end D may be larger than the diameters of pipe end A and pipe end C, or the diameters of pipe end A, pipe end B, pipe end C, and pipe end D may all be the same. In particular, since the optical film 13 is formed at pipe end B and pipe end D, it is preferable to make the diameters of pipe end B and pipe end D larger than the diameters of pipe end A and pipe end C so that the optical film 13 is formed relatively widely, allowing the flow of the gas containing particles to be observed over a wide area. Similarly, it is also preferable to have a configuration in which the diameter of the first pipe 6 is larger than the diameter of the second pipe 2.

[0035] (Means of observation) In this embodiment, the observation means 21 contacts the light film 13 at the intersection 5 and observes the scattered light emitted by the passing particles. If the section from the upstream end of the second tube 2 to the intersection 5 is a straight tube, the observation means 21 should be 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 should be designated as the observation direction 22.

[0036] On the other hand, if the observation means 21 is located on the axis of the second tube 2, the optical film 13 formed inside the first tube 6 should be adjusted so that the surface of the optical film and the observation direction 22 by the observation means 21 are perpendicular at the intersection 5. This allows scattered light generated from particles passing through the optical film 13 to be captured over a wide area.

[0037] Incidentally, Patent Document 3 discloses technology related to particle sensors. In this technology, the device is designed to detect scattered light from a direction parallel to the surface of a laser sheet emitted from a light source, and the relationship between the gas flow direction, the surface of the optical film 13, and the observation direction 22 differs from that of the vacuum piping particle monitoring device 1 according to this embodiment. In the technology of Patent Document 3, when a large number of particles flow instantaneously, the scattered light from the particles overlaps and is detected as a unified light pulse, raising concerns about detection loss. Also, from the perspective of the detector, the focus is adjusted to be parallel to the surface of a laser sheet having a predetermined width, that is, adjusted to increase the depth of field, resulting in a detector with a large F-number and a relatively dark optical system, raising concerns that it will be difficult to detect the weak scattered light emitted by minute particles.

[0038] On the other hand, in the vacuum piping particle monitoring device 1 according to this embodiment, at the intersection 5, the optical film 13 is formed so that its surface covers 10% or more of the cross-sectional area of ​​the second pipe 2. Here, if the thickness of the optical film 13 is 3 mm or less, and at the intersection 5, the surface of the optical film 13 and the observation direction 22 by the observation means 21 are perpendicular, the depth of field of the observation means 21 can be relatively thin, a bright optical system can be used, and the particle group can be captured as a wide two-dimensional image. Therefore, even if many particles flow simultaneously over a wide area, observation can be performed 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, etc. can be used as appropriate.

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

[0041] (Second Embodiment) The vacuum piping particle monitoring device 1 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 on the first pipe 6. The light-shielding plate 14 is preferably provided at a position other than the intersection 5 of the first pipe 6 and in a position that does not come into contact with the light film 13. The vacuum piping particle monitoring device 1 is structured to block the flow of gas from both ends of the first pipe 6 by providing lids 8 and 9 at both ends of the first pipe 6 in order to maintain a vacuum state inside the pipe. When a light film is incident on the first pipe 6 from the outside, the light will pass through the light-transmitting lid 9, but depending on the material of the lid 9, some degree of light diffusion may occur when the light passes through the lid 9. This diffused light brightly illuminates the inner surface of the pipe, which serves as the background from the perspective of the observation means 21, and may cause a deterioration in the contrast between the scattered light from the particles and the background. By using the vacuum piping particle monitoring device 1 according to the second embodiment, such diffused light is shielded by the light-shielding plate 14, making it possible to sufficiently darken the background and observe the scattered light of weak particles at the intersection with good contrast. Figures 14 and 15 show the state of the intersection 5 inside the second pipe 2 as observed in the observation direction 22, with Figure 14 showing the case without the light-shielding plate 14 and Figure 15 showing the case with the light-shielding plate installed.

[0042] The light-shielding plate 14 is preferably made of a material that has light-shielding properties, such as a stainless steel plate, preferably a stainless steel plate that has been treated with a black finish, and more preferably a stainless steel plate that has been treated with a black electroless nickel plating finish.

[0043] In this embodiment, the light-shielding plate 14 is preferably provided such that its surface is substantially perpendicular to the optical axis direction 13a of the optical film 13, in order to block diffused light. Examples of the form of the light-shielding plate 14 include a form in which an opening slightly larger than the width and thickness of the optical film 13 is provided so that the optical film 13 can pass through the plate (see Figure 5), and a form of a substantially semicircular disc having an arc portion formed to be in contact with the inner circumferential surface of the first tube 6 without any gaps, and a chord portion 14c (see Figure 6). When the light-shielding plate 14 is provided on the first tube 6, it is preferable that the chord portion 14c of the substantially semicircular disc be parallel to the surface of the optical film 13 so as not to come into contact with the optical film 13.

[0044] The light-shielding plate 14 only needs to have a thickness of about 1 mm, and it is preferable that the chord portion 14c on one side has a chamfered portion 14b that is beveled along the chord. When the light film 13 is formed on the first tube 6 in the configuration with the light-shielding plate 14, the chord portion 14c of the light-shielding plate 14 may become reflective due to light reflection, making it difficult to observe the particles. A light-shielding plate 14 with a chamfered portion 14b can make the intersection 5 darker, which is advantageous for observing the particles. The angle α of the chamfer is not particularly limited, but for example, it is preferable to set the angle of the chord portion 14c on one side of the light-shielding plate 14 to approximately 45° with respect to the thickness direction. The light-shielding plate 14 can be provided such that the other side without the chamfered portion 14b faces the intersection 5.

[0045] Referring to Figures 3, 7, and 8, the light-shielding plates 14 can be provided in multiple quantities, for example, 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 into which the optical film 13 from the optical film forming means 11 enters is considered the upstream side of the optical film, and the side with the beam trap 12 is considered the downstream side of the optical film, then the first light-shielding plate 141 in this embodiment should be positioned such that its surface is approximately perpendicular to the optical axis direction 13a of the optical film 13, at a distance L1 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 from the upstream corner 6a of the first tube 6 at the intersection 5. Note that the corners 6a, 6b, ... are the joints between the first tube 6 and the second tube 2. The roughly semicircular first light-shielding plate 141 can be placed in the space 17 behind the formed light film 13 inside the first tube 6 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 also be placed upstream of the first tube 6 from the first light-shielding plate 141, with a gap L2 between them. The gap L2 can be, for example, longer than 0 mm, more preferably 10 mm or more, and ideally 20 mm or more. The second light-shielding plate 142 can be placed in the space 16 in front of the formed light film 13 inside the first tube 6 when the first tube 6 is viewed from the observation means 21 in the observation direction 22 (-z direction). This arrangement allows for the blocking of light diffused into the space 17 behind the first tube 6 and the light diffused into the space 16 in front of the first tube 6, making it easier to observe the particles.

[0046] In addition to the first light-shielding plate 141 and the second light-shielding plate 142 described above, a third light-shielding plate 143 and a fourth light-shielding plate 144 can also be provided downstream of the intersection 5 in the first tube 6. In this embodiment, the third light-shielding plate 143 is preferably positioned at a distance L3 from the downstream corner 6b 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 downstream corner 6b of the first tube 6 at the intersection 5), such that the plate surface is substantially perpendicular to the optical axis direction 13a of the optical film 13. The substantially semicircular third light-shielding plate 143 can be provided in the space 17 inside the first tube 6, behind the formed optical 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 from the third light-shielding plate 143, with a gap L4 between them. The gap L4 can be, for example, longer than 0 mm, more preferably 10 mm or more, and ideally 20 mm or more. Here, the fourth light-shielding plate 144 can be provided in the space 16 in front of the formed light film 13 inside the first tube 6, when the first tube 6 is viewed from the observation means 21 in the observation direction 22 (-z direction). By arranging it in this way, the light diffused into the space 17 at the back of the first tube 6 and the light diffused into the space 16 at the front can be blocked, making it easier to observe the particles.

[0047] When installing the first light-shielding plate 141, it is sufficient that the first light-shielding plate 141 and the light film 13 are separated by a distance L5. Similarly, when installing the second light-shielding plate 142, the third light-shielding plate 143, and the fourth light-shielding plate 144, each of them should be separated from the light film 13 by a distance L5. The distance L5 is preferably 2 mm or less, more preferably 1.5 mm or less, more preferably 1 mm or less, and most preferably 0.5 mm or less.

[0048] The light-shielding plate 14 is positioned so as not to come into contact with the optical film 13. Specifically, when the axial direction of the first tube 6 is the y-direction, the optical axis direction 13a of the optical film 13 is the y-direction, the surface of the optical film 13 is the xy-plane, and the observation direction 22 is the -z-direction, when the first light-shielding plate 141 is placed in the space 17 on the back side, the chord portion 14c of the first light-shielding plate 141 should be positioned parallel to the surface of the optical film 13. Similarly, for the second light-shielding plate 142, the third light-shielding plate 143, and the fourth light-shielding plate 144, the chord portions 14c of each should be positioned parallel to the surface of the optical film 13.

[0049] The shape of the edge of the curved portion of the light-shielding plate 14 should match the shape of the cross-section obtained when the first pipe 6 is cut in the circumferential direction. By doing so, the edge of the curved portion of the light-shielding plate 14 can be aligned with the inner circumferential surface of the first pipe 6, and the light-shielding plate 14 can be fixed to the first pipe 6 by closing the curved portion and the inner circumferential surface so that there is no gap.

[0050] (Third embodiment) When observing particles in a vacuum, light may be scattered and diffused inside the tube, causing the background to become brighter and making it difficult to observe with good contrast. Therefore, the vacuum piping particle monitoring device 1 according to the 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 tube 6 and the second tube 2 are made black. By making the inner surface of the tube black, the reflection and diffusion of light inside the tube can be suppressed, and the contrast between the scattered light image of particles contained in the gas flowing through the second tube 2 and the surrounding background is improved. To make it black, for example, black anodizing or Raydent® treatment can be performed. However, even if the inner surface of the tube is black, outgassing and particles may be generated. If these are generated, they may flow back into the tube and contaminate the manufactured product during or before / after processing such as film formation in the manufacturing equipment. Therefore, it is more preferable to treat the inner surface of the tube with black electroless nickel plating. By treating the inner surface of the tube with black electroless nickel plating, not only is observation with good contrast possible, but the generation of outgassing and particles, which tend to occur in a vacuum, can also be suppressed.

[0051] Figure 13 is a graph plotting the outgassing rate against exhaust time for pipes with various treatments applied to their inner surfaces. Reference numeral 61 represents a pipe treated with black anodizing, reference numeral 62 represents a pipe treated with Raydent® (1st time), reference numeral 63 represents a pipe treated with Raydent® (2nd time), reference numeral 64 represents a pipe treated with black electroless nickel plating, reference numeral 65 represents a pipe made of SUS304L treated with glass bead blasting (GBB), and reference numeral 66 represents a pipe made of SUS304L treated with electropolishing. From Figure 13, it can be seen that black electroless nickel plating suppresses outgassing more effectively than black anodizing or Raydent® treatment.

[0052] One or both of the inner surfaces of the first tube 6 and the second tube 2 can be made black by plating (hot-dip plating, vacuum plating, electroless plating, electrolytic plating, etc.). Examples of electrolytic methods include black electrolytic chromium 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. Tubes plated with black electroless nickel are particularly preferable because, as mentioned above, they suppress light reflection and diffusion, as well as outgassing and particle generation.

[0053] Furthermore, it is also desirable to install the light-shielding plate 14 on the first pipe 6, and to make one or both of the inner surfaces of the first pipe 6 and the second pipe 2 black.

[0054] Even in the vacuum piping particle monitoring device 1 according to the third embodiment, a light-shielding plate 14 may be provided on the first pipe 6 in combination with the second embodiment.

[0055] (others) Regarding the drawings, the optical film 13 shown in Figure 2 is formed inside the first tube 6 and is not visible from the outside, but it is shown for explanatory purposes. The first tube 6 and the second tube 2 in Figure 3 are cylindrical in shape, but are shown in cross-section for explanatory purposes. [Examples]

[0056] A particle observation test was conducted using this embodiment. The procedure was as follows: For the vacuum piping particle monitoring device according to this embodiment, a turbomolecular pump was connected to the vacuum chamber, its exhaust was connected to the gas supply section of the vacuum piping particle monitoring device, and the gas discharge section was connected to a dry pump. The pumps were started, and the atmospheric pressure inside the tubes of the vacuum piping particle monitoring device was set to 1 Pa or less. A laser sheet light source with a wavelength of 450 nm was used as the photofilm formation means. A CMOS camera was used as the observation means, and the frame rate was set to 60 FPS (frames / second). For the first tube in which the photofilm is formed and the second tube through which the gas flows, NW25 standard tubes with a diameter of 23 mm were used, and the diameter of the intersection was set to 23 mm. The cross-sectional area of ​​the second tube through which the gas flows (at the intersection) was set to 415 mm². 2 The area of ​​the optical film at the intersection is set to 313 mm². 2 Furthermore, at the intersection, the optical film was formed such that the surface area of ​​the optical film occupied 75.4% of the cross-sectional area of ​​the intersection.

[0057] The liquid crystal deposition apparatus in the vacuum chamber was started and stopped to generate particles, and the movement of the generated particles through the intersection was imaged over time using an observation device and counted. The results are shown in Figures 9 to 12. A characteristic peak 41 of the particle 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 peak 42 of the particle was observed 300 seconds after the start of observation. Figure 11 shows the appearance of peak 42 of observed particle 54. In addition, a characteristic peak 43 of the particle was observed 1350 seconds after the start of observation. Figure 12 shows the appearance of peak 43 of observed particle 54.

[0058] The observed particles 54 showed variability in size. At peak 41, mainly small particles with a diameter of 0.5 μm or more and less than 1 μm, and medium-sized particles with a diameter of 1 μm or more and less than 5 μm were observed. At peak 42, in addition to small and medium-sized particles, large particles with a diameter of 5 μm or more were observed. In particular, Figure 11 shows a density difference, with the particle density being denser on the left side of the observed area and sparser on the right side. [Industrial applicability]

[0059] This invention is applicable to the visualization of gas flow and particle image velocity measurement methods. It is applicable to all fields where particle flow is of interest, such as semiconductors, liquid crystals, pharmaceuticals, food, medical, automotive, film, and metal processing. [Explanation of Symbols]

[0060] 1. Particle monitoring device in vacuum piping 2 2nd pipe 3. Gas supply unit 4. Gas discharge 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. Light-blocking plate 14a opening 14b Chamfered section 15 Irradiation area 21 Observation methods 22 Observation direction 31 Gases 40 Vacuum Chamber 41 Peak 42 Peak 43 Peak 51 Number of small particles 52 Number of medium-sized particles 53 Number of large-sized particles 54 Observed Particles

Claims

1. A first pipe having one end, The second pipe through which a gas containing particles flows, The intersection where the first pipe and the second pipe intersect, A light film forming means that causes light to enter the first tube from one end and forms a planar light film with a thickness of 3 mm or less beyond the intersection, A vacuum means for creating a vacuum inside the first tube and the second tube, The system includes a two-dimensional image sensor for observing scattered light emitted by the aforementioned particles, The observation direction by the two-dimensional image sensor is along the axis of the second tube and intersects the surface of the optical film. At the intersection, the surface of the optical film is formed over 10% or more of the cross-sectional area of ​​the second tube. The scattered light is emitted when the particles flowing through the second tube come into contact with the surface of the optical film at the intersection. A particle monitoring device in vacuum piping, characterized by the following features.

2. At the intersection, the surface of the optical film and the observation direction by the two-dimensional image sensor are orthogonal. The vacuum piping particle monitoring apparatus according to claim 1.

3. It has a light-shielding plate, The light-shielding plate is provided in a position other than the intersection of the first tube and in a position that does not come into contact with the light film. The vacuum piping particle monitoring apparatus according to claim 1.

4. The inner surface of the first tube and the inner surface of the second tube, or both, are treated with black electroless nickel plating. The vacuum piping particle monitoring apparatus according to claim 1.

5. A first pipe having one end, The second pipe through which a gas containing particles flows, The intersection where the first pipe and the second pipe intersect, A light film forming means that causes light to enter the first tube from one end and forms a planar light film with a thickness of 3 mm or less beyond the intersection, A vacuum means for creating a vacuum inside the first tube and the second tube, The system includes a two-dimensional image sensor for observing scattered light emitted by the aforementioned particles, The observation direction by the two-dimensional image sensor is along the axis of the second tube and intersects the surface of the optical film. At the intersection, the surface of the optical film is formed over 10% or more of the cross-sectional area of ​​the second tube. The scattered light is emitted when the particles flowing through the second tube come into contact with the surface of the optical film at the intersection, using a vacuum piping particle monitoring device. A light film is formed inside the first tube, The inside of the first tube and the inside of the second tube are brought into a vacuum state. The gas is passed through the second pipe, The scattered light emitted from the particles at the intersection is observed by the two-dimensional image sensor. A method for monitoring particles in a vacuum pipe, characterized by the following features.

Images