Observation device

Abstract

The present invention provides an observation device that makes it possible to observe the flow of a specific type of gas among a plurality of types of gas which exist in an observation region. An observation device (60) comprises a background image (61), an imaging unit (62), a wavelength selection unit (63), and a computer. The imaging unit (62) has an imaging sensor (622) that images a background image (61) through an observation region (S) in which an air flow exists. The wavelength selection unit (63) is disposed between the background image (61) and the imaging sensor (622). The wavelength selection unit (63) selectively transmits light of a specific wavelength. Thus, the imaging unit (62) is able to capture an image of the background image (61) created by light of a specific wavelength. Therefore, it is possible for the computer to apply a background-oriented schlieren method to the captured image that is obtained and thereby observe the flow of a specific type of gas among a plurality of types of gas which exist in the observation region.

Description

Observation equipment

[0001] The present invention relates to an observation device for observing airflow.

[0002] Conventionally, there are known apparatuses that perform substrate cleaning processes by supplying a processing liquid to substrates such as semiconductor wafers. In these types of apparatuses, even a slight change in the airflow within the chamber can cause a decrease in product quality. Therefore, there is a need for a technology that can observe the state of the airflow within the chamber while performing substrate cleaning processes.

[0003] One known technique for observing airflow is the background oriented Schlieren (BOS) method, which captures a background image through an observation area where airflow is formed and measures the distortion of the background image in the captured image to calculate the state of airflow in the observation area.

[0004] A conventional apparatus using the background type Schlieren method is described in, for example, Patent Document 1.

[0005] Japanese Patent Application Laid-Open No. 2020-143917

[0006] However, when multiple types of gases are present in the observation area, the conventional background schlieren method measures the image distortion caused by the sum of the refractive indices of the mixed gases, and observes the flow of the mixed gas as a whole. For this reason, the conventional background schlieren method was unable to observe the flow of a specific type of gas within a mixed gas.

[0007] The present invention has been made in view of the above circumstances, and has as its object to provide an observation device that can observe the flow of a specific type of gas among multiple types of gases present in an observation area.

[0008] In order to solve the above problem, the first invention of the present application is an observation device for observing airflow, comprising: a background image; an imaging unit having an imaging sensor that captures the background image through an observation area where the airflow exists; a wavelength selection unit that is positioned between the background image and the imaging sensor and selectively transmits light of a specific wavelength; and a computer that calculates the state of the airflow by a background-type Schlieren method using the image acquired by the imaging unit.

[0009] A second aspect of the present invention is the observation device of the first aspect, wherein the wavelength selection section is an interference filter that transmits light of the specific wavelength.

[0010] A third aspect of the present invention is the observation device of the first or second aspect, wherein the specific wavelength is an absorption wavelength of a gas to be observed.

[0011] A fourth invention of the present application is an observation device according to any one of the first to third inventions, comprising a beam splitter that splits light emitted from or reflected from the background image and transmitted through the observation area into a first optical path and a second optical path, a first imaging unit that is the imaging unit arranged in the first optical path, and a second imaging unit that is arranged in the second optical path, and the wavelength selection unit is arranged only in the first optical path out of the first optical path and the second optical path.

[0012] The fifth invention of the present application is an observation device for observing airflow, comprising: a background image; an imaging unit having an imaging sensor that captures the background image through an observation area where the airflow exists; and a computer that calculates the state of the airflow by a background Schlieren method using the image acquired by the imaging unit, wherein the wavelength of light emitted from or reflected from the background image is the absorption wavelength of the gas that is the object of observation among the gases present in the observation area.

[0013] A sixth aspect of the present invention is the observation device of the fifth aspect of the present invention, further comprising a projector that projects the background image onto a background surface on which the background image is to be placed using light of the absorption wavelength.

[0014] According to the first to sixth aspects of the present invention, a background image can be captured using light of a specific wavelength, making it possible to observe the flow of a specific type of gas among multiple types of gas present in the observation area by the background schlieren method.

[0015] In particular, according to the fourth invention of the present application, the first imaging unit can observe the flow of a specific type of gas among multiple types of gas present in the observation area, and the second imaging unit can observe the flow of all types of gas.

[0016] FIG. 1 is a vertical sectional view of a substrate processing apparatus; FIG. 2 is a block diagram showing electrical connections between a control unit and each unit in the substrate processing apparatus; FIG. 3 is a conceptual diagram of an observation device; FIG. 4 is a graph showing the absorption spectrum of a gas; FIG. 5 is a conceptual diagram of an observation device equipped with two imaging units; and FIG. 6 is a conceptual diagram of an observation device equipped with a projector.

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0018] 1 is a longitudinal sectional view of a substrate processing apparatus 1 equipped with an observation apparatus 60 according to one embodiment. The substrate processing apparatus 1 is an apparatus for supplying a processing liquid to the surface of a disk-shaped substrate W to clean the substrate W during a semiconductor wafer manufacturing process. As shown in FIG. 1, the substrate processing apparatus 1 includes a chamber 10, a substrate holder 20, a rotation mechanism 30, a processing liquid supply unit 40, and a computer 50.

[0019] The chamber 10 is a housing that contains a processing space 11 for processing a substrate W. The chamber 10 has a sidewall 12 that surrounds the sides of the processing space 11, a top plate 13 that covers the upper part of the processing space 11, and a bottom plate 14 that covers the lower part of the processing space 11. The substrate holder 20, the rotation mechanism 30, and the nozzle 45 of the processing liquid supply unit 40 are housed inside the chamber 10. A loading / unloading port for loading and unloading the substrate W into and from the chamber 10, and a shutter for opening and closing the loading / unloading port are provided in part of the sidewall 12.

[0020] The substrate holding unit 20 is a mechanism that holds the substrate W horizontally (with its normal oriented vertically) inside the chamber 10. As shown in FIG. 1 , the substrate holding unit 20 includes a disk-shaped spin base 21 and a plurality of chuck pins 22. The plurality of chuck pins 22 are provided on the outer periphery of the upper surface of the spin base 21. The substrate W is held by the plurality of chuck pins 22 with its processing surface, on which a pattern is to be formed, facing upward. Each chuck pin 22 contacts the lower surface and outer peripheral edge surface of the peripheral edge of the substrate W, and supports the substrate W at a position above the upper surface of the spin base 21 with a small gap therebetween.

[0021] The rotation mechanism 30 is a mechanism for rotating the substrate holding part 20. As shown in Fig. 1, the rotation mechanism 30 has a motor 31 and a support shaft 32. The support shaft 32 extends vertically, and its lower end is connected to the motor 31, while its upper end is fixed to the center of the lower surface of the spin base 21. When the motor 31 is driven, the support shaft 32 rotates around its axis 320. Then, together with the support shaft 32, the substrate holding part 20 and the substrate W held by the substrate holding part 20 also rotate around the axis 320.

[0022] The processing liquid supply unit 40 is a mechanism that supplies a processing liquid to the upper surface of the substrate W held by the substrate holder 20. The processing liquid supply unit 40 has a liquid supply source 41, a liquid supply pipe 42, a valve 43, a pump 44, and a nozzle 45. The liquid supply source 41 is a tank that stores the processing liquid before supply. Examples of processing liquids that can be used include an SPM cleaning liquid (a mixture of sulfuric acid and hydrogen peroxide), an SC-1 cleaning liquid (a mixture of ammonia water, hydrogen peroxide, and pure water), an SC-2 cleaning liquid (a mixture of hydrochloric acid, hydrogen peroxide, and pure water), a DHF cleaning liquid (dilute hydrofluoric acid), and pure water (deionized water).

[0023] The liquid supply pipe 42 is a pipe that connects the liquid supply source 41 and the nozzle 45. The valve 43 and the pump 44 are provided on the path of the liquid supply pipe 42. The nozzle 45 is disposed opposite to the upper surface of the substrate W. When the valve 43 is opened and the pump 44 is operated, the processing liquid is supplied from the liquid supply source 41 through the liquid supply pipe 42 to the nozzle 45. Then, the processing liquid is discharged from the nozzle 45 toward the center of the upper surface of the substrate W.

[0024] The processing liquid discharged from the nozzle 45 onto the upper surface of the substrate W spreads from the center of the substrate W to the outside due to centrifugal force caused by the rotation of the substrate W. The processing liquid scattered to the outside from the substrate W is collected in a cup (not shown) and then discharged to the outside of the chamber 10.

[0025] The computer 50 is an information processing device for controlling the operation of each part of the substrate processing apparatus 1. Fig. 2 is a block diagram showing the electrical connection between the computer 50 and each part in the substrate processing apparatus 1. As conceptually shown in Fig. 2, the computer 50 has a processor 51 such as a CPU, a memory 52 such as a RAM, and a storage unit 53 such as a hard disk drive.

[0026] An operation control program P1 and an air current observation program P2 are stored in the storage unit 53. The operation control program P1 is a computer program for controlling the operation of each unit of the substrate processing apparatus 1 in order to process substrates W in the substrate processing apparatus 1. The air current observation program P2 is a computer program for observing the state of air currents in the chamber 10 based on images obtained from an imaging unit 62, which will be described later.

[0027] 2, the computer 50 is electrically connected to the chuck pins 22, the motor 31, the valve 43, and the pump 44. The computer 50 controls the operation of each of the above components in accordance with an operation control program P1 stored in the storage unit 53. This allows the cleaning process of the substrate W in the substrate processing apparatus 1 to proceed. The computer 50 is also electrically connected to an imaging unit 62, which will be described later. The computer 50 performs an observation process of the airflow in the chamber 10 based on images obtained from the imaging unit 62.

[0028] <2. Observation Device> During the cleaning process of the substrate W, various air currents are generated in the chamber 10 due to the downflow of purified air, the discharge of the processing liquid, the evaporation of the processing liquid, changes in gas temperature, etc. These air currents may affect the cleaning quality of the substrate W. Therefore, the substrate processing apparatus 1 is provided with an observation device 60 that observes the state of the air current in a predetermined observation region S in the chamber 10.

[0029] As shown in FIG. 1, the observation device 60 includes a background image 61, an imaging unit 62, an interference filter 63, and the computer 50 described above.

[0030] The background image 61 is an image placed inside the chamber 10. The background image 61 may be a geometrically repeating pattern such as dots or stripes, or may be a random pattern or design. The background image 61 is placed on the surface of a structure inside the chamber 10. The background image 61 is placed on a plane that intersects with the optical axis A of the observation device 60.

[0031] 1, a background image 61 is fixedly formed on the surface of a structure inside the chamber 10. However, the background image 61 may be a projected image formed by projecting light onto the surface of the structure inside the chamber 10 from outside the chamber 10.

[0032] The imaging unit 62 is a unit that captures a background image 61. The imaging unit 62 is disposed outside the chamber 10. A transparent window 15 is provided in the sidewall 12 of the chamber 10. The imaging unit 62 captures the background image 61 inside the chamber 10 through an interference filter 63, the window 15, and the observation area S. As shown in FIG. 1 , the imaging unit 62 has an imaging optical system 621 and an imaging sensor 622. The imaging optical system 621 includes one or more lenses. The imaging sensor 622 includes an imaging element such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS).

[0033] The image sensor 622 receives light incident from the background image 61 through the observation area S, the window 15, the interference filter 63, and the image capturing optical system 621. This allows a multi-tone captured image composed of multiple pixels to be obtained. The image sensor 622 also obtains multiple captured images by repeatedly capturing images at short time intervals. The obtained captured images are input from the image sensor 622 to the computer 50.

[0034] The computer 50 uses the captured image input from the imaging unit 62 to calculate the state of the airflow in the observation area S by the background oriented Schlieren (BOS) method.

[0035] The interference filter 63 is an optical filter that selectively transmits light of a specific wavelength λs. The interference filter 63 is an example of a "wavelength selection unit" in the present invention. The interference filter 63 is disposed between the background image 61 and the image sensor 622. In this embodiment, the interference filter 63 is disposed between the window 15 of the chamber 10 and the image capturing unit 62. However, the interference filter 63 may be disposed inside the chamber 10. Alternatively, the interference filter 63 may be disposed inside the image capturing unit 62.

[0036] Fig. 3 is a conceptual diagram of the observation device 60. A ray L1 in Fig. 3 indicates light traveling from a part of the background image 61 toward the image sensor 622 when a specific type of gas G to be observed is not present in the observation area S. A ray L2 in Fig. 3 indicates light traveling from a part of the background image 61 toward the image sensor 622 when the gas G is present in the observation area S.

[0037] As shown in Figure 3, when gas G is present in the observation area S, the difference in refractive index between the gas G and other gases causes a displacement of the light rays passing through the observation area S. This causes a change in the incident positions of light rays L1 and L2 at the position of the image sensor 622. As a result, the background image 61 is distorted in the captured image acquired by the image capturing unit 62. The computer 50 measures the distortion of the background image 61 in this captured image. Then, the computer 50 calculates the state of the airflow in the observation area S based on the measured distortion of the background image 61.

[0038] In this embodiment, an interference filter 63 is inserted on the optical path between the background image 61 and the image sensor 622. Therefore, of the light of all wavelengths λall contained in the light beams L1 and L2 incident on the interference filter 63, light of a specific wavelength λs is selectively transmitted through the interference filter 63. Therefore, the image sensor 622 captures an image of the background image 61 using light of the specific wavelength λs.

[0039] The specific wavelength λs does not necessarily have to be a wavelength in the visible region. For example, the specific wavelength λs may be a wavelength in the infrared region. In that case, the image sensor 622 may be a sensor capable of capturing infrared light.

[0040] FIG. 4 is a graph showing the absorption spectrum of a certain gas G. The horizontal axis of FIG. 4 represents the wavelength of light. The vertical axis of FIG. 4 represents the absorbance by the gas G. As shown in FIG. 4, the gas G exhibits high absorbance at a specific absorption wavelength λa. In other words, the gas G has the property of easily absorbing light of the absorption wavelength λa. The absorption wavelength λa varies depending on the type of gas. For example, oxygen, nitrogen, carbon dioxide, water vapor, etc. each have a different absorption wavelength λa. When the gas G is present, the light of the absorption wavelength λa is absorbed by the gas G. As a result, of the light of all wavelengths λall incident on the gas G, the amount of light of the absorption wavelength λa decreases.

[0041] In this embodiment, the interference filter 63 is selected so that the specific wavelength λs, which is the wavelength of light transmitted through the interference filter 63, is the absorption wavelength λa of the gas G to be observed. In other words, an interference filter 63 is used such that the range of the absorption wavelength λa and the range of the specific wavelength λs at least partially overlap.

[0042] As a result, in areas of the observation area S where the gas G to be observed is not present, light of the specific wavelength λs that is transmitted through the gas G and the interference filter 63 is incident on the image sensor 622. Therefore, in areas of the captured image where the gas G is not present, a relatively bright background image 61 appears due to the light of the specific wavelength λs. On the other hand, in areas of the observation area S where the gas G to be observed is present, the light of the specific wavelength λs is absorbed by the gas G, and the amount of light of the specific wavelength λs that is incident on the image sensor 622 decreases. Therefore, in areas of the captured image where the gas G is present, the background image 61 appears darker than in areas where the gas G is not present.

[0043] The computer 50 recognizes a relatively dark portion in the captured image input from the imaging unit 62 as a region of interest where the gas G to be observed is present. The computer 50 also calculates the flow of the gas G in the observation region S by applying the background Schlieren method to the region of interest in the captured image. That is, the computer 50 measures the distortion of the background image 61 in the region of interest in the captured image, and calculates the flow of the gas G in the observation region S based on the amount of distortion measured.

[0044] As described above, in this observation device 60, by using the interference filter 63, it is possible to obtain an image captured by light of a specific wavelength λs corresponding to the gas G to be observed. Therefore, by applying the background schlieren method to the obtained captured image, it is possible to observe the flow of a specific type of gas G among multiple types of gases present in the observation region S.

[0045] The computer 50 calculates the flow of the specific gas G in the observation region S by the above-described method while performing the cleaning process on the substrate W. The computer 50 then monitors whether the calculated airflow state is within a predetermined allowable range. If the calculated airflow state is outside the allowable range, the computer 50 executes abnormality response control. The abnormality response control may be, for example, displaying a warning on a display unit such as a display, turning on a warning lamp, or sounding a warning sound. The abnormality response control may also be outputting information indicating the abnormality to an external terminal. The abnormality response control may also be stopping or limiting the cleaning process on the substrate W. This allows a user of the substrate processing apparatus 1 to recognize that the airflow state in the observation region S is outside the allowable range.

[0046] 3. Modifications Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. Various modifications will be described below, focusing on the differences from the above embodiment.

[0047] <3-1. First Modification> In the above embodiment, the observation device 60 captured the background image 61 using one imaging unit 62. However, by branching the optical path, the background image 61 may be captured using multiple imaging units 62. Fig. 5 is a conceptual diagram of an observation device 60 equipped with two imaging units (hereinafter referred to as a first imaging unit 62A and a second imaging unit 62B).

[0048] The observation device 60 in Fig. 5 includes a first image capturing unit 62A, a second image capturing unit 62B, and a beam splitter 64. The beam splitter 64 is disposed between the observation area S and the two image capturing units 62A and 62B. Light emitted from or reflected from the background image 61 and transmitted through the observation area S is split by the beam splitter 64 into a first optical path PA and a second optical path PB. The first image capturing unit 62A is disposed on the first optical path PA. The second image capturing unit 62B is disposed on the second optical path PB.

[0049] As in the above embodiment, an interference filter 63 is disposed in the first optical path PA. Therefore, in the first optical path PA, light of the specific wavelength λs that has passed through the interference filter 63 is incident on the first imaging unit 62A. Therefore, the first imaging unit 62A captures an image of the background image 61 using the specific wavelength λs. On the other hand, in the example of FIG. 5 , an interference filter 63 is not disposed in the second optical path PB. Therefore, in the second optical path PB, light of all wavelengths λall is incident on the second imaging unit 62B. Therefore, the second imaging unit 62B captures an image of the background image 61 using all wavelengths λall.

[0050] 5, the interference filter 63 is disposed only in the first optical path PA out of the first optical path PA and the second optical path PB. In this manner, the computer 50 can observe the flow of a specific type of gas G among the multiple types of gases present in the observation region S using the captured image obtained from the first image capturing unit 62A, and can also observe the flows of all types of gas using the captured image obtained from the second image capturing unit 62B.

[0051] Furthermore, interference filters 63 that transmit light of different wavelengths may be disposed in the first optical path PA and the second optical path PB. In this way, different types of gas flows can be observed in the first imaging unit 62A and the second imaging unit 62B. Furthermore, the optical path may be branched into three or more paths, and different interference filters 63 may be disposed in each optical path.

[0052] <3-2. Second Modification> In the above embodiment, the interference filter 63 is used to selectively allow light having the absorption wavelength λa of the gas G to be observed to be incident on the imaging unit 62. However, without using the interference filter 63, the wavelength of the light itself emitted from or reflected by the background image 61 may be set to the absorption wavelength λa of the gas G to be observed. For example, the wavelength of the illumination light that illuminates the background image 61 may be set to the absorption wavelength λa of the gas G to be observed.

[0053] Alternatively, the background image 61 may be projected by a projector 65. Fig. 6 is a conceptual diagram of an observation device 60 equipped with a projector 65. In the example of Fig. 6, the projector 65 projects the background image 61 onto a background surface on which the background image 61 is to be placed. The wavelength of the projection light from the projector 65 is set to the absorption wavelength λa of the gas G to be observed.

[0054] In this way, the background image 61 itself is formed at the absorption wavelength λa of the gas G to be observed. Therefore, light with the absorption wavelength λa can be incident on the image capturing unit 62 without using an interference filter 63 for selecting a wavelength. Therefore, the computer 50 can observe the flow of a specific type of gas G among multiple types of gases present in the observation region S, using the captured image obtained from the first image capturing unit 62A.

[0055] Furthermore, for example, the background image 61 may be formed by a light source arranged in a plane, such as a display, and light having an absorption wavelength λa of the gas G to be observed may be emitted from the background image 61 displayed by the light source arranged in a plane.

[0056] <3-3. Other Modifications> In the above embodiment and modification 1, the interference filter 63 is used as the wavelength selection unit that selectively transmits light of a specific wavelength λs. However, the wavelength selection unit is not limited to the interference filter 63, and may be a prism, a spectroscope, or the like.

[0057] Furthermore, if the absorption spectrum of the gas G to be observed has peak values ​​at multiple wavelengths, multiple images may be obtained using the multiple wavelengths as specific wavelengths, and the gas G may be observed by combining these images.

[0058] In the above embodiment, an apparatus has been described that performs a cleaning process on a substrate W. However, the apparatus in which the observation apparatus of the present invention is installed may be an apparatus that performs a process other than a cleaning process. Furthermore, the apparatus in which the observation apparatus of the present invention is installed may be an apparatus that performs a process on an object other than a substrate W.

[0059] However, in an apparatus that supplies a processing liquid to a substrate W for precision electronic components such as a semiconductor wafer, it is necessary to extremely precisely control the state of the air flow within the chamber 10. For this reason, it is particularly significant that the observation device of the present invention is installed in the apparatus that supplies a processing liquid to the substrate W.

[0060] The observation device of the present invention is not limited to a device to be mounted on a specific processing device, but may be a device for general use. The observation device may also be one used outdoors. The observation device may also be one in which the projector 65 that projects the background image 61 and the imaging unit 62 are integrally configured.

[0061] Furthermore, the elements appearing in the above-described embodiments and modifications may be combined as appropriate within the scope of not causing any contradictions, or some of them may be deleted.

[0062] REFERENCE SIGNS LIST 1 substrate processing apparatus 10 chamber 20 substrate holding section 30 rotation mechanism 40 processing liquid supply section 50 computer 60 observation device 61 background image 62 imaging section 62A first imaging section 62B second imaging section 63 interference filter 64 beam splitter 65 projector 621 imaging optical system 622 imaging sensor A optical axis G gas L1 light ray L2 light ray PA first optical path PB second optical path S observation area W substrate λa absorption wavelength λs specific wavelength

Claims

1. An observation device for observing air currents, comprising: a background image; an imaging unit having an image sensor that captures the background image through an observation area in which the air current exists; a wavelength selection unit that is disposed between the background image and the image sensor and selectively transmits light of a specific wavelength; and a computer that uses the image acquired by the imaging unit to calculate the state of the air current by the background type Schlieren method.

2. An observation device according to claim 1, wherein the wavelength selection section is an interference filter that transmits light of the specific wavelength.

3. An observation device according to claim 1 or 2, wherein the specific wavelength is an absorption wavelength of a gas to be observed.

4. An observation device as described in any one of claims 1 to 3, comprising: a beam splitter that splits light emitted from or reflected from the background image and transmitted through the observation area into a first optical path and a second optical path; a first imaging unit that is the imaging unit and is arranged in the first optical path; and a second imaging unit that is arranged in the second optical path, wherein the wavelength selection unit is arranged only in the first optical path out of the first optical path and the second optical path.

5. An observation device for observing air currents, comprising: a background image; an imaging unit having an image sensor that captures the background image through an observation area in which the air current exists; and a computer that calculates the state of the air current by a background-type Schlieren method using the image acquired by the imaging unit, wherein the wavelength of light emitted from or reflected from the background image is the absorption wavelength of the gas that is to be observed among the gases present in the observation area.

6. An observation device according to claim 5, further comprising a projector for projecting the background image onto a background surface on which the background image is to be placed, using light of the absorption wavelength.

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