JP2015096830A - Substrate processing apparatus and substrate processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique capable of reliably determining a holding state of a substrate with a simple structure without requiring a fine position adjustment work.SOLUTION: The substrate processing device includes: holding means 11 for holding a substrate W in an approximately horizontal attitude; rotation means 113 for rotating the holding means 11 around a substantially vertical axis; a processing chamber 90 for forming a processing space SP for storing the holding means 11; illumination means 71 for introducing illumination light into the processing chamber 90; imaging means 72 for imaging the substrate W held by the holding means 11; and determination means 81, 86 for determining a holding state of the substrate W by the holding means 11 on the basis of a comparison result of an image content of a comparison object region between a plurality of images imaged with a rotational phase angle different from each other by setting a region including at least a part not including a regular reflection image of the illumination means 71 within the surface of the substrate W from the image imaged by the imaging means 72 as a comparison object region.

Description

  The present invention relates to a substrate processing apparatus and a substrate processing method for rotating a substrate while maintaining the substrate in a substantially horizontal posture.

  As a technique for performing various processes such as a cleaning process and a coating process on a substrate, there is a technique for performing a process while rotating the substrate while maintaining the substrate in a substantially horizontal posture. In particular, in a process performed by supplying a liquid to the substrate, such a technique is widely used because the liquid can be uniformly supplied to the substrate surface by a centrifugal force accompanying the rotation of the substrate.

  In this technique, in order to enable high-speed rotation of the substrate, it is necessary that the substrate is securely held by holding means for holding the substrate. This is because if the holding of the substrate is incomplete or held in a state inclined with respect to the rotation axis, problems such as the substrate dropping off due to the rotation and being damaged or the apparatus being damaged may occur. Such incomplete holding is caused by improper operations such as misalignment when the substrate is placed on the holding means, and the holding means holds the substrate properly due to corrosion by chemicals or mechanical damage. It can be caused by loss of function.

  In order to avoid the above problems, a technique for detecting the holding state of the substrate carried into the apparatus has been proposed. For example, in the technique described in Patent Document 1, the position of the orientation flat of the substrate or the placement failure is detected from the light reception result of light that is intermittently shielded by the substrate by irradiating the end of the substrate with convergent beam light. To do. In the technique described in Patent Document 2, reflected light of laser light irradiated toward the substrate surface is received by a line sensor, and the tilt of the substrate is detected from the light receiving position.

Japanese Patent Laid-Open No. 02-086144 JP 2003-229403 A

  In the prior art, the substrate is irradiated with a convergent light beam, the light beam shielded or reflected by the substrate is received, and the holding state of the substrate is determined. Accordingly, the positional accuracy between the light emitter that emits the light beam and the light receiver that receives the light beam affects the detection accuracy. Therefore, precise position adjustment work between the light emitter and the light receiver is required. In addition, vibrations of the device that occur during processing can cause erroneous detection. For these reasons, it is required to establish a technique that can reliably determine the holding state of the substrate with a simple configuration without requiring a fine position adjustment operation.

  The present invention has been made in view of the above problems. In a substrate processing apparatus and a substrate processing method for rotating a substrate while maintaining the substrate in a substantially horizontal posture, a fine position adjustment operation is not required, and the substrate can be reliably configured with a simple configuration. It is an object of the present invention to provide a technique capable of determining a holding state.

  In one aspect of the substrate processing apparatus according to the present invention, in order to achieve the above object, a holding means for holding the substrate in a substantially horizontal posture, a rotating means for rotating the holding means about a substantially vertical axis, and the holding means A processing chamber for forming a processing space for housing the processing chamber, an illuminating unit for introducing illumination light into the processing chamber, an imaging unit for imaging the substrate held in the holding unit, and an image captured by the imaging unit The comparison target region between a plurality of images picked up with different rotational phase angles of the substrate, with a region including at least a part of the substrate surface not including the regular reflection image of the illumination unit as a comparison target region Determination means for determining the holding state of the substrate by the holding means based on the comparison result of the image contents.

  According to another aspect of the substrate processing method of the present invention, in order to achieve the above object, a holding means for holding the substrate in a substantially horizontal posture in the processing chamber holds the substrate, and the substrate is illuminated. A plurality of images of the substrate held by the holding means, the rotation phase angle around the vertical axis of the substrate being different from each other, and each of the plurality of captured images A region that includes at least a part of the surface that does not include a regular reflection light component of illumination light is set as a comparison target region, and the substrate by the holding unit is based on a comparison result of image contents of the comparison target region between the plurality of images. And determining the holding state.

  In the invention configured as described above, a comparison is made between a plurality of images that are picked up with different rotation phase angles of the substrate, and a region that does not include the specularly reflected light component of the illumination light in the imaged substrate surface. The image content of the target area is compared to determine the holding state of the substrate. When the substrate held by the holding unit has an abnormality such as tilt or misalignment, the image contents are different between a plurality of images having different rotation phase angles of the substrate. In the present invention, since the holding state of the substrate is determined by a relative comparison between these images, and the specular reflection component is not used for the determination, it is necessary to receive the specular reflection light on the substrate surface of the illumination light. Absent. Therefore, it is not necessary to adjust the optical path of the illumination light and the regular reflection light on the substrate surface.

  In addition, it is sufficient for the illumination light to be provided in the processing chamber with a brightness that enables imaging of the substrate surface, and it is not always necessary to directly irradiate the substrate. It may be an aspect that is incident on the surface. Further, the illumination light does not need to be convergent light. As described above, according to the present invention, it is possible to reliably determine the holding state of the substrate with a simple configuration without requiring a fine position adjustment operation.

  As a first aspect of more specific determination, for example, the holding state may be determined based on the comparison result of the luminance of the comparison target region between a plurality of images. For example, when the substrate is held in an inclined state, the angle at which the substrate surface is viewed from the imaging means varies depending on the rotational phase angle of the substrate. As a result, the brightness of the substrate surface as viewed from the imaging means changes, so that it is possible to determine the holding state of the substrate by a relative comparison of luminance between a plurality of images.

  More specifically, for example, if the difference in luminance value between the highest and lowest luminances of the comparison target region among a plurality of images is within a predetermined first threshold, the holding state is normal. On the other hand, when the difference between the luminance values exceeds the first threshold, the holding state may be determined to be abnormal. In such a configuration, determination can be made quantitatively based on image data obtained by imaging.

  In this case, for example, the difference between the sum of the pixel values of each pixel included in the comparison target region in one image and the sum of the pixel values of each pixel included in the comparison target region in the other image is calculated as 2 It can be a difference in luminance value between two images. With such a configuration, determination can be performed quantitatively and extremely simply based only on image data.

  In addition, as a more specific second aspect of the determination, for example, each of the plurality of images includes an image of a specific part in the processing chamber reflected on the surface of the substrate, and the specific part of the imaged substrate surface The region including the image may be a comparison target region, and the holding state may be determined based on the comparison result of the position of the image of the specific part between the plurality of images. An image of a structure in the processing chamber is reflected on the surface of the substrate held in the processing chamber. If the substrate is tilted, the position of the image viewed from the imaging means varies depending on the rotational phase angle of the substrate. Therefore, among the structures in the processing chamber, the position where the image is reflected on the substrate surface and that can be distinguished from other structures is a specific part, and the relative position of the image is compared between multiple images. By doing so, it is possible to determine the holding state of the substrate.

  More specifically, for example, information on the position of the image of the specific part on the substrate normally held by the holding unit is held in advance, and the position specified by the information and the specific part in each of the plurality of images are stored. If the amount of positional deviation from the image position is within a predetermined second threshold, it is determined that the holding state is normal, while if the amount of positional deviation exceeds the second threshold, it is determined that the holding state is abnormal. It may be configured as follows. As described above, the determination as to the comparison with the image in the normal holding state makes it possible to more reliably determine the holding state of the substrate.

  Further, for example, if the maximum value of the relative positional deviation amount of the image of the specific part between the plurality of images is within a predetermined third threshold value, the holding state is determined to be normal, while the positional deviation amount is the third threshold value. If it exceeds, the holding state may be determined to be abnormal. According to such a configuration, it is possible to easily determine the holding state of the substrate based only on the plurality of captured images.

  In order to enable such determination, for example, a position reference mark that functions as a specific part may be provided at a position facing the substrate surface in the processing chamber. According to such a configuration, a position reference mark having a shape specialized for position detection can be provided, and the holding state of the substrate is easily determined from the position of the position reference mark image reflected on the substrate in a plurality of images. be able to.

  As a third mode of more specific determination, for example, the comparison target region includes a part of the peripheral edge of the substrate, and the size of the area occupied by the substrate in the comparison target region is set between a plurality of images. The holding state may be determined by comparison. For example, when the substrate is circular and is held in an eccentric state with respect to the rotation axis, the position of the peripheral edge of the fixed point observation varies with the rotation of the substrate. At this time, the area of the substrate occupying the comparison target region varies between a plurality of images picked up with different rotation phase angles of the substrate. Therefore, the holding state of the substrate can be determined by relative comparison of the area of the substrate in the comparison target region between the plurality of images.

  In this case, for example, if the area difference between the highest and lowest substrate areas in the comparison target region among the plurality of images is within a predetermined fourth threshold, the holding state is normal. On the other hand, when the area difference exceeds the fourth threshold value, the holding state may be determined to be abnormal. According to such a configuration, since the holding state is determined based on the magnitude of the change in the area of the substrate in the comparison target region, the area occupied by the substrate in the comparison target region in the normal holding state is not known in advance. Can also determine the holding state.

  Further, for example, the number of pixels corresponding to the substrate among the pixels included in the comparison target region may be configured to be information indicating the area of the substrate occupying the comparison target region. Since the number of pixels corresponding to the substrate increases as the area occupied by the substrate increases, the number of pixels is information that accurately represents the area of the substrate in the comparison target region. Therefore, the holding state of the substrate can be easily determined by counting the number of pixels.

  Further, for example, in each aspect described above, the imaging unit may be disposed at a position where the regular reflection light of the illumination light from the substrate surface does not enter in the processing chamber. As described above, in the present invention, the holding state is determined without using the regular reflection light from the substrate. Therefore, it is not necessary for the image pickup means to be provided at a position for receiving regular reflection light from the substrate. Rather, there is a risk of erroneous determination because the state of incidence of specularly reflected light on the imaging means changes depending on the rotational phase angle of the substrate due to improper holding of the substrate. Such a problem can be avoided in advance by disposing the imaging means at a position where the regular reflection light from the substrate of the illumination light does not enter.

  According to the present invention, the holding state of the substrate is determined by the relative comparison of the image contents of the area of the substrate surface that does not include the specularly reflected light component of the illumination light among the plurality of images obtained by imaging the substrate held by the holding unit. Therefore, it is possible to reliably determine the holding state of the substrate with a simple configuration without requiring a fine position adjustment operation.

It is a figure which shows schematic structure of the substrate processing system concerning this invention. It is a top view which shows the structure of one substrate processing unit. It is a figure which shows the structure of the control part of the AA arrow cross section of FIG. 2, and a substrate processing unit. It is a flowchart which shows operation | movement of a substrate processing unit. It is the 1st figure explaining the judgment principle in the 1st example. It is the 2nd figure explaining the judgment principle in the 1st example. It is the 1st figure explaining the judgment principle in the 2nd example. It is the 2nd figure explaining the judgment principle in the 2nd example. It is a figure explaining the determination principle in a 3rd example.

  Hereinafter, an outline of a substrate processing system including a substrate processing apparatus to which the present invention can be applied will be described. FIG. 1 is a diagram showing a schematic configuration of a substrate processing system according to the present invention. More specifically, FIG. 1 is a top view of an embodiment of a substrate processing system to which the present invention can be suitably applied. The substrate processing system 1 includes substrate processing units 1A, 1B, 1C, and 1D that can execute predetermined processing on substrates independently of each other, and substrates between these substrate processing units 1A to 1D and the outside. The indexer unit 1E in which an indexer robot (not shown) for transferring the information is disposed, and the control unit 80 (FIG. 3) for controlling the operation of the entire system are provided.

  The substrate processing units 1 </ b> A to 1 </ b> D are partially different in layout of each part depending on the arrangement position in the substrate processing system 1, but the components provided in each unit and their operations are the same. Therefore, hereinafter, the configuration and operation of one of the substrate processing units 1A will be described, and detailed description of the other substrate processing units 1B to 1D will be omitted. The number of substrate processing units may be arbitrary, and a configuration may be adopted in which four substrate processing units arranged in the horizontal direction as one stage are stacked in a plurality of stages in the vertical direction.

  FIG. 2 is a top view showing the structure of one substrate processing unit. 3 is a diagram showing a cross section taken along the line AA of FIG. 2 and the configuration of the control unit of the substrate processing unit. The substrate processing unit 1A is a single-wafer type wet processing unit for performing wet processing such as cleaning with a processing liquid and etching processing on a disk-shaped substrate W such as a semiconductor wafer. In the substrate processing unit 1 </ b> A, a fan filter unit (FFU) 91 is disposed on the ceiling portion of the chamber 90. The fan filter unit 91 includes a fan 911 and a filter 912. Therefore, the external atmosphere taken in by the operation of the fan 911 is supplied to the processing space SP in the chamber 90 through the filter 912. The substrate processing system 1 is used in a state where it is installed in a clean room, and clean air is always sent into the processing space SP.

  A substrate holder 10 is provided in the processing space SP of the chamber 90. The substrate holding unit 10 holds and rotates the substrate W in a substantially horizontal posture with the substrate surface facing upward. The substrate holding unit 10 includes a spin chuck 11 in which a disc-shaped spin base 111 having an outer diameter slightly larger than that of the substrate W and a rotation support shaft 112 extending in a substantially vertical direction are integrally coupled. . The rotation support shaft 112 is connected to a rotation shaft of a chuck rotation mechanism 113 including a motor, and the spin chuck 11 can be rotated around a rotation axis (vertical axis) by driving from the chuck drive unit 85 of the control unit 80. Yes. The rotation support shaft 112 and the chuck rotation mechanism 113 are accommodated in a cylindrical casing 12. In addition, the spin base 111 is integrally connected to the upper end portion of the rotation support shaft 112 by fastening parts such as screws, and the spin base 111 is supported by the rotation support shaft 112 in a substantially horizontal posture. Therefore, when the chuck rotation mechanism 113 is operated, the spin base 111 rotates about the vertical axis. The control unit 80 can adjust the rotation speed of the spin base 111 by controlling the chuck rotating mechanism 113 via the chuck driving unit 85.

  Near the periphery of the spin base 111, a plurality of chuck pins 114 for holding the peripheral end of the substrate W are provided upright. Three or more chuck pins 114 may be provided to securely hold the circular substrate W (six in this example), and are arranged at equiangular intervals along the peripheral edge of the spin base 111. Each of the chuck pins 114 is configured to be switchable between a pressing state in which the outer peripheral end surface of the substrate W is pressed and a released state in which the chuck pin 114 is separated from the outer peripheral end surface of the substrate W.

  When the substrate W is delivered to the spin base 111, each of the plurality of chuck pins 114 is released, while when the substrate W is rotated to perform a predetermined process, the plurality of chuck pins 114 are released. Each is made into a press state. By setting the pressing state in this manner, the chuck pin 114 can hold the peripheral end portion of the substrate W and hold the substrate W in a substantially horizontal posture at a predetermined interval from the spin base 111. As a result, the substrate W is supported with its front surface facing upward and the back surface facing downward. As the chuck pin 114, a known configuration, for example, one described in JP 2013-206983 A can be used. The mechanism for holding the substrate is not limited to the chuck pin, and for example, a vacuum chuck that holds the substrate W by sucking the back surface of the substrate may be used.

  A splash guard 20 is provided around the casing 12 so as to be movable up and down along the rotation axis of the spin chuck 11 so as to surround the periphery of the substrate W held in a horizontal posture on the spin chuck 11. The splash guard 20 has a shape that is substantially rotationally symmetric with respect to the rotation axis, and is arranged concentrically with the spin chuck 11 to receive a plurality of stages (in this example, two stages) for receiving the processing liquid scattered from the substrate W. A) a guard 21 and a liquid receiving portion 22 for receiving the processing liquid flowing down from the guard 21. A guard elevating mechanism (not shown) provided in the control unit 80 raises and lowers the guard 21 in stages, so that it is possible to separate and collect treatment liquids such as chemicals and rinse liquids scattered from the rotating substrate W. It has become.

  Around the splash guard 20, at least one liquid supply unit for supplying various processing liquids such as a chemical liquid such as an etching liquid, a rinsing liquid, a solvent, pure water, and DIW (deionized water) to the substrate W is provided. . In this example, as shown in FIG. 2, three sets of processing liquid discharge units 30, 40 and 50 are provided. The treatment liquid discharge unit 30 is driven by an arm driving unit 83 of the control unit 80 and is configured to be rotatable about a vertical axis, and an arm extending in the horizontal direction from the rotary shaft 31. 32 and a nozzle 33 attached downward to the tip of the arm 32. As the pivot shaft 31 is pivotally driven by the arm drive unit 83, the arm 32 swings around the vertical axis, and the nozzle 33 thereby moves the splash guard 20 as indicated by a two-dot chain arrow in FIG. It reciprocates between a retracted position (a position indicated by a solid line in FIG. 3) outside and a position above the rotation center of the substrate W (a position indicated by a dotted line in FIG. 3). The nozzle 33 discharges a predetermined processing liquid supplied from the processing liquid supply unit 84 of the control unit 80 while being positioned above the substrate W, and supplies the processing liquid to the substrate W.

  Similarly, the processing liquid discharge section 40 is provided from a processing liquid supply section 84 provided at a pivot shaft 41 that is rotationally driven by an arm driving section 83, an arm 42 connected thereto, and a tip of the arm 42. And a nozzle 43 for discharging the processed liquid. Further, the processing liquid discharge section 50 is provided from a processing liquid supply section 84 provided at a pivot shaft 51 that is rotationally driven by an arm driving section 83, an arm 52 coupled thereto, and a tip of the arm 52. And a nozzle 53 for discharging the processing liquid. Note that the number of treatment liquid discharge units is not limited to this, and may be increased or decreased as necessary.

  In a state where the substrate W is rotated at a predetermined rotation speed by the rotation of the spin chuck 11, these processing liquid discharge units 30, 40, 50 sequentially position the nozzles 33, 43, 53 above the substrate W to supply the processing liquid. By supplying the substrate W, the cleaning process of the substrate W is executed. Depending on the purpose of processing, different processing liquids may be discharged from the nozzles 33, 43, 53, or the same processing liquid may be discharged. Two or more kinds of processing liquids may be discharged from one nozzle. The processing liquid supplied in the vicinity of the rotation center of the substrate W spreads outward due to the centrifugal force accompanying the rotation of the substrate W, and is finally shaken off laterally from the peripheral edge of the substrate W. The processing liquid splashed from the substrate W is received by the guard 21 of the splash guard 20 and collected by the liquid receiving portion 22.

  Further, in the processing space SP of the chamber 90, an illumination unit 71 that illuminates the processing space SP and a camera 72 that images the surface of the substrate W held by the spin chuck 11 are provided. The illumination unit 71 uses, for example, an LED lamp as a light source, and supplies illumination light necessary to enable imaging by the camera 72 into the processing space SP. The camera 72 is disposed above the substrate W in the processing space SP toward the substrate W, and includes the entire surface of the substrate W held by the spin chuck 11 in its visual field.

  As shown in FIG. 2, the camera 72 is provided outside a region (region sandwiched between the broken lines L1 and L2) included in a range in which the substrate W is viewed from the illumination unit 71 in plan view. For this reason, it is avoided that the regular reflection light of the light directly incident on the substrate W from the illumination unit 71 enters the camera 72. That is, the camera 72 is provided at a position that avoids the path of regular reflection light on the surface of the substrate W of illumination light. On the other hand, when the camera 72 is provided in a region sandwiched between the broken lines L1 and L2 as indicated by a dotted line in FIG. 2, for example, the specularly reflected light from the substrate W is incident on the camera 72. Become.

  Although details will be described later, in this substrate processing system 1, the holding state of the substrate W is determined using an image obtained by imaging the surface of the substrate W by the camera 72, but at this time, the regular reflected light from the substrate W is not included. Judgment is performed using an image. In the technique of performing determination using a specularly reflected light component as in the prior art, the optical axis shift between the light source and the camera affects the determination accuracy. However, in the substrate processing system 1, a plurality of images that do not include specularly reflected light. Therefore, such a problem of optical axis misalignment does not occur. In this case, since the specularly reflected light component can be rather a disturbance, the positions of the illumination unit 71 and the camera 72 are determined so that the specularly reflected light on the surface of the substrate W does not enter the camera 72.

  The image data acquired by the camera 72 is given to the image processing unit 86 of the control unit 80. The image processing unit 86 performs predetermined image processing on the image data, and acquires information necessary for determining the holding state of the substrate W.

  In addition to the above, the control unit 80 of the substrate processing system 1 includes a CPU 81 that executes a predetermined processing program to control the operation of each unit, a processing program executed by the CPU 81, and data generated during the processing. And a display unit 87 for notifying the user of the progress of the process and the occurrence of an abnormality as necessary. The control unit 80 may be provided individually for each of the substrate processing units 1A to 1D, or only one set is provided in the substrate processing system 1 so as to control the substrate processing units 1A to 1D in an integrated manner. It may be configured. The CPU 81 may also have a function as an image processing unit.

  Next, the operation of the substrate processing unit 1A configured as described above will be described. In addition, although description is abbreviate | omitted, other board | substrate processing units 1B-1D operate | move similarly. The substrate processing unit 1A receives a substrate W carried in from the outside via the indexer unit 1E, supplies various processing liquids while rotating the substrate W, and executes wet processing. There are many known techniques using various processing liquids as the wet process, and any of them can be applied, and the description of the wet process is omitted.

  The operational feature of the substrate processing unit 1A is that the substrate W is held by the spin chuck 11 until the substrate W is placed on the spin chuck 11 and rotated and subjected to wet processing at a predetermined rotational speed. The point is that the state is determined. In other words, when the substrate W is started to rotate and before the processing speed is reached, the holding state of the substrate W is determined using an image captured by the camera 72, and if it is determined that the substrate is in a normal holding state. While executing the scheduled wet process, the rotation of the substrate W is immediately stopped when it is determined that the holding state is abnormal. The processing contents will be described below.

  FIG. 4 is a flowchart showing the operation of the substrate processing unit. This operation is realized by the CPU 81 executing a predetermined processing program. When the substrate W is loaded into the substrate processing unit 1A, the substrate W is placed on the spin chuck 11, more specifically, a plurality of chuck pins 114 provided on the periphery of the spin base 111 (step S101). When the substrate W is carried in, the chuck pins 114 provided on the spin base 111 are in a released state. After the substrate W is placed, the chuck pins 114 are switched to a pressed state, and the substrate W is chucked. 114 (step S102).

  At this time, the holding of the substrate W by the chuck pins 114 may be incomplete, for example, because the mounting position of the substrate W is inappropriate. For example, the substrate W may be placed in a state where it rides on one of the chuck pins 114, and thus the substrate W may be held in a state of being inclined from a horizontal posture. Further, for example, the shape of the chuck pin 114 may gradually change due to corrosion by the chemical solution, which may make it impossible to hold the substrate W or hold the substrate W in an eccentric state.

  If the substrate W is rotated in such a state, the substrate W may drop from the spin chuck 11 and be damaged, or the device may be damaged by colliding with a component in the chamber 90. Even if the substrate does not fall out, abnormal vibrations may occur in the apparatus by rotating the substrate W in a tilted or eccentric state. In order to prevent such a problem, the substrate processing unit 1A determines the holding state of the substrate W by the spin chuck 11 by observing the behavior of the substrate W using an image captured by the camera 72. To do.

  Specifically, the substrate W is continuously imaged by the camera 72 while operating the chuck driving unit 85 to rotate the spin chuck 11 at a low speed (step S103) (step S104). Thereby, a plurality of images having different rotation phase angles of the substrate W are acquired. Then, the image processing unit 86 calculates a predetermined feature amount from each obtained image (step S105). The “feature amount” here is an amount that can be quantitatively calculated as a numerical value from the captured image, and includes when the substrate W is normally held and when it is in an inappropriate holding state. It can take different values.

  More specifically, when the substrate W is normally held, there is little fluctuation between a plurality of images having different rotation phase angles, while when the substrate W is in an inappropriate holding state, the fluctuation between the plurality of images is increased. This amount is suitable as the “feature amount”. In particular, a feature amount that does not depend on a specularly reflected light component on the surface of the substrate W of illumination light is preferable. Various features can be considered as such feature amounts, and specific examples thereof will be described later.

  When the feature amount in each image is obtained, the CPU 81 determines whether or not the variation amount of the feature amount between a plurality of images having different rotation phase angles is within a predetermined allowable range (step S106). As described above, since the feature amount is selected such that the variation is small if the holding state of the substrate W is appropriate, if the variation amount of the feature amount is within the allowable range (“YES” in step S106). It can be determined that the holding state of the substrate W is normal. Therefore, in this case, the rotation speed of the substrate W is increased to a predetermined value for wet processing (step S107), and then a predetermined wet processing is executed (step S108). The description of the content of the wet process is omitted.

  On the other hand, when the variation amount of the feature amount accompanying the change in the rotation phase angle exceeds the allowable range (“NO” in step S106), it can be determined that the holding state of the substrate W is abnormal. Accordingly, the rotation drive of the spin chuck 11 is immediately stopped to stop the rotation of the substrate W, and a message indicating that there is an abnormality in holding the substrate W by the spin chuck 11 is displayed on the display unit 87 to notify the user ( Step S111). Instead of or in addition to the message display, for example, an abnormality notification by a warning sound may be performed.

  In this way, by taking an image with the camera 72 while rotating the substrate W at a low speed, and determining the holding state based on the relative variation amount of the feature amount between a plurality of images having different rotation phase angles of the substrate W, It is avoided that the substrate W is rotated at a high speed in an inappropriate holding state and the substrate W and the apparatus are damaged. As described above, the feature amount that does not depend on the specularly reflected light component on the surface of the substrate W of the illumination light is used to determine the holding state based on the imaging result. Three specific examples will be described below.

<First example>
5 and 6 are diagrams for explaining the determination principle in the first example. In the first example of determining the holding state based on the imaging result, the holding state is determined based on a change in luminance on the surface of the substrate W caused by the inclination of the substrate W on the spin chuck 11. That is, the feature amount in this example is the luminance of the surface of the substrate W.

  As shown on the left side of FIG. 5A, in a state where the substrate W is properly held by the spin chuck 11, that is, in a state where the surface of the substrate W is substantially horizontal, the normal vector N of the surface of the substrate W is vertically upward. This is invariant regardless of the rotational phase angle of the substrate W. Although the surface of the substrate W is illuminated by the illumination unit 71, the regular reflection light on the surface of the substrate W does not enter the camera 72, and the illumination light is scattered in the chamber 90 and indirectly incident on the surface of the substrate W. The reflected light is received mainly by the camera 72. The state of the surface of the substrate W imaged by the camera 72 is schematically shown on the right side of FIG. Since the illumination light does not change and the inclination of the substrate W viewed from the camera 72 is constant regardless of the rotation phase angle of the substrate W, the luminance of the image of the surface of the substrate W to be imaged also depends on the rotation phase angle of the substrate W. It is expected to be almost constant.

  On the other hand, as shown on the left side of each of FIGS. 5B to 5D, when considering the case where the substrate W is held in a state of being tilted on a part of the chuck pins 114, for example, from the camera 72. The inclination of the substrate W to be viewed varies depending on the rotation phase angle, and accordingly, the luminance of the surface of the imaged substrate W varies according to the rotation phase angle of the substrate W, as shown on the right side of each figure.

  When the illumination light is sufficiently scattered in the chamber 90 and does not have a specific directionality, for example, as shown in FIG. 5B, the normal vector Vn on the surface of the substrate W has a component directed in the opposite direction to the camera 72. In this case, it is considered that the amount of light incident on the camera 72 from the surface of the substrate W decreases and the luminance of the surface of the substrate W decreases. If the rotation phase angle φ of the substrate W at this time is 0 degree, in the state of FIG. 5D where the rotation phase angle φ is 180 degrees, the component in which the normal vector Vn on the surface of the substrate W is directed toward the camera 72. The amount of light incident on the camera 72 from the substrate W is increased, and the luminance of the substrate W in the captured image is further increased. In the middle of these, that is, in the state where the rotational phase angle φ shown in FIG. 5C is 90 degrees, the luminance of the surface of the substrate W is considered to be an intermediate value.

  Therefore, the brightness of at least a part of the image captured by the camera 72 corresponding to the surface of the substrate W, for example, the region R1 near the center of the substrate W as shown in FIG. It is possible to determine whether or not the substrate W is tilted by comparing a plurality of images having different rotational phase angles. Specifically, it can be as follows.

As shown in FIG. 6A, for a partial region R1 corresponding to the surface of the substrate W in the image captured by the camera 72, each pixel included in the region R1 is represented by a symbol P (i, j). I will do it. Here, the parameters i and j represent the coordinate position of the pixel in the region R1. If the width of the area R1 is M pixels and the height is N pixels, the coordinates of the upper left corner (or lower left corner) of the area R1 are (0, 0), and the lower right corner (or The coordinates of the (corner) pixel can be represented by (M−1, N−1). When the luminance value (pixel value) of each pixel P (i, j) included in the region R1 is represented by the symbol I (i, j), the luminance value Ir of the region R1 is defined by the following equation.

  When the luminance value Ir of the region R1 is obtained for each of a plurality of images picked up with different rotational phase angles φ of the substrate W and plotted against the rotational phase angle φ, for example, as shown in FIG. The luminance value Ir changes periodically with a maximum period of one rotation of the substrate W (that is, φ = 360 degrees). Here, in the state where the surface of the substrate W is uniform and is held horizontally by the spin chuck 11, the luminance value Ir is considered to be a constant value regardless of the rotational phase angle φ. However, more generally, periodic fluctuations appear due to an allowable minute inclination of the substrate W and a difference in the surface state of the substrate W at each position.

  If the holding state of the substrate W by the spin chuck 11 is appropriate and the substrate W is held in a substantially horizontal posture, the variation amount of the luminance value Ir is relatively small as shown by the curve A in FIG. On the other hand, when the substrate W is held in an inclined state as shown in FIG. 5B, the periodic fluctuation of the luminance value Ir becomes larger as shown by the curve B in FIG. 6B. From this, for example, an appropriate threshold value Th1 is set in advance for the variation amount of the luminance value Ir, and if the variation amount of the luminance value Ir obtained from a plurality of captured images is within the threshold value Th1, the holding state is set. When the threshold value Th1 is exceeded, it can be determined that the holding state of the substrate W is abnormal.

  More specifically, for example, a plurality of images are captured for at least one rotation of the substrate W, and the difference between the maximum value and the minimum value of the luminance value Ir obtained for each region R in each image is greater than the threshold Th1. If it is larger, it can be determined that the holding state of the substrate W is abnormal. Further, for example, the luminance value Ir is calculated without delay each time an image is taken, and the maximum value and the minimum value of the calculated luminance value Ir are stored, and stored when it is determined that the difference between them exceeds the threshold Th1. It may be determined that the state is abnormal. In any case, the rotation amount of the substrate W until the holding state is determined can be within one rotation.

  The threshold Th1 can be experimentally determined in advance according to the allowable tilt amount of the substrate W, the surface state of the substrate W, the brightness in the processing space SP, and the like. In addition, since the position and area of the region R1 are made the same among a plurality of images and the holding state is determined based on the amount of variation in the luminance value Ir, the mere total value of the pixel values of the pixels included in the region R1 is It can be used as the luminance value Ir of the region R1. That is, in this example, the determination can be made if the relative change amount accompanying the rotation of the substrate W of the numerical value indicating the luminance of the surface of the substrate W can be obtained, and any scale indicating the luminance can be used.

  Further, since it is not necessary to cause the specularly reflected light or transmitted light to enter the camera 72, it is not necessary to adjust the optical axis, and it is not necessary to use a light source that emits a convergent light beam as an illumination light source. In addition, since the determination is performed based on the relative change amount rather than the absolute luminance value, it is sufficient that the illumination condition does not change while the substrate W rotates, and it is not necessary to adjust the brightness of the light source strictly. As described above, in this example, it is possible to reliably determine the holding state of the substrate with a simple configuration without requiring fine adjustment work.

  In the above example, for each of a plurality of images having different rotation phase angles φ of the substrate W, the total pixel value of the pixels included in the region R1 in the image is obtained as the luminance value Ir. The luminance value Ir is compared between a plurality of images. However, it is technically equivalent even if the order of operations is changed and the difference between the pixel values corresponding to each other between the two images is obtained and the values are summed for the entire region R1, and the same result as above is obtained. can get.

<Second example>
7 and 8 are diagrams for explaining the determination principle in the second example. This example is particularly effective when the surface of the substrate W has a high reflectance close to a mirror surface. In such a case, an image of a structure provided at a position facing the surface of the substrate W in the processing space SP illuminated by the light from the illumination unit 71 is formed on the surface of the substrate W held in the chamber 90. Reflect. For example, as shown in FIG. 7A, if a structure 92 having a known shape is provided on the ceiling portion of the chamber 90 corresponding to the upper partition wall of the processing space SP, an image of the structure 92 reflected on the surface of the substrate W. Is captured by the camera 72.

  When the shape of the structure 92 is, for example, a star shape, the captured image corresponds to the shape of the structure 92 at a position facing the structure 92 on the surface of the substrate W as shown in FIG. A shape image Ia appears. When attention is paid to the region R2 including the position where the image Ia of the structure 92 is reflected in the image, the structure 92 in the region R2 is maintained regardless of the rotation phase angle of the substrate W if the substrate W is held in a horizontal posture. The position of the image Ia is considered to be almost unchanged.

  On the other hand, as shown in FIGS. 8A to 8C, if the substrate W is held by the spin chuck 11 in a state of being inclined from the horizontal posture, the amount of inclination of the surface of the substrate W viewed from the camera 72 can be reduced. By changing according to the rotation phase angle, the position of the image Ia in the region R2 periodically varies. A star Ib indicated by a dotted line on the right side of each figure represents the position of the image Ia when it is assumed that the substrate W is not inclined.

  Therefore, as shown in FIG. 8D, when an appropriate amount (herein referred to as “position index amount”) indicating the position of the image Ia in the region R2 is plotted against the rotational phase angle φ of the substrate W, If the inclination of the substrate W is within the allowable range, the fluctuation of the value is small as shown by the curve A. On the other hand, if the substrate W is inclined, a larger periodic fluctuation appears as shown by the curve B. Therefore, a predetermined threshold value Th2 is set in advance for the amount of fluctuation of the position index amount, that is, the relative displacement amount of the image Ia accompanying the rotation of the substrate W, and the position index amount associated with the rotation of the substrate W. If the fluctuation amount is within the threshold value Th2, the holding state of the substrate W is normal, and if it exceeds the threshold value Th2, it can be determined that the holding state is abnormal. That is, the position index amount in this example corresponds to the “feature amount” described above.

  The position index amount will be described. Most simply, the position of the image Ia can be indicated by the position of a representative point (for example, the center of gravity of the image) that can be identified from the image Ia of the structure 92. Therefore, for example, the position index amount can be determined by the difference (that is, the distance) of the representative point position between a plurality of images captured while rotating the substrate W. Further, for example, a distance between a predetermined reference point (for example, the center of gravity of the image Ib of the structure 92 when it is assumed that the substrate W is not inclined) and the representative point in each image may be used as the position index amount.

  However, in this case, for example, when the trajectory of the representative point associated with the rotation of the substrate W is a circle centered on the reference point, the substrate W is calculated from the position index amount expressed only by the distance from the reference point, which is a scalar amount. It may be difficult to grasp the inclination of the. Further, in FIG. 8 and the like, the tilt of the substrate W and the image positional deviation are emphasized, but the tilt of the substrate W in an actual apparatus is very small, and the position fluctuation of the image Ia is slight. Therefore, sufficient determination accuracy may not be obtained by such determination based only on the position of the image.

  As a more accurate method, using the image Ib of the structure 92 when assuming that the substrate W is not inclined as a template, the degree of overlap between this template and the image Ia of the actually captured structure 92 is pattern-matched. It is conceivable to quantify by processing and use the value as a position index amount. Specifically, a matching coordinate or a matching score obtained by pattern matching can be used as the position index amount.

  When the substrate W is held on the spin chuck 11 without being tilted, the image Ia of the structure 92 is observed almost overlapping with the reference image Ib regardless of the rotation phase angle φ of the substrate W. That is, the variation of the matching score and the matching coordinates due to the rotation phase angle φ of the substrate W is small. On the other hand, when the substrate W is held in an inclined state, the matching score and the matching coordinates change greatly depending on the rotation phase angle φ of the substrate W. By setting an appropriate threshold value Th2 for these numerical fluctuation amounts, the holding state of the substrate W can be accurately determined.

  Various techniques can be applied as the pattern matching process. Here, some examples will be given, but the explanation of the principle is omitted because each technique is known. Hereinafter, the luminance value of each pixel P (i, j) in the template is T (i, j), and the luminance value of each pixel P (i, j) in the region R2 of each captured image is I (i, j). ). The definitions of parameters i and j are the same as in the first example.

(1) When Normalized Cross Correlation (NCC) is Used The similarity with the template of the region R2 in each image can be expressed by the following mathematical formula. The closer the left side similarity _RNCC is to 1, the higher the similarity between the two images, that is, the position of the image Ib of the structure 92 in the captured image is closer to the position of the image Ia in the template. In this case, the value R _{NCC on} the left side corresponds to the matching score.

(2) When using SSD (Sum of Squared Difference) The following formulas can represent the degree of similarity with the template of the region R2 in each image. The smaller the value R _{SSD on} the left side, the higher the similarity between the two images. In this case, the value R _{SSD on} the left side corresponds to the matching score.

(3) When SAD (Sum of Absolute Difference) is Used The similarity with the template of the region R2 in each image can be expressed by the following mathematical formula. Also in this case, the smaller the value R _{SAD on} the left side, the higher the similarity between the two images. In this case, the value R _{SAD on} the left side corresponds to the matching score.

  Note that the pattern matching method is not limited to these, and various known techniques can be applied. In the above description, either the matching coordinates or the matching score is used to determine the holding state of the substrate W from the amount of change, but these may be used together. That is, when both the matching coordinates obtained by the pattern matching process and the matching score exceed a predetermined threshold, it is determined as abnormal, or when at least one of these exceeds a threshold, it is determined as abnormal. It is possible to do.

<Third example>
The two examples described above are modes suitable mainly for detecting the tilt of the substrate W. On the other hand, the third example described below corresponds to the inclination of the substrate W as in the above example, and in particular, the circular substrate W is eccentric, that is, the geometric center and the rotation center of the substrate W are shifted. It is suitable for detecting the state held by the spin chuck 11 in the state where the magnetic field is held.

  FIG. 9 is a diagram for explaining the determination principle in the third example. In this example, the holding state of the substrate W is determined based on the image content of the region R3 partially including at least a part of the peripheral end portion of the substrate W in the image captured by the camera 72. When the substrate W is circular, if the substrate W is held by the spin chuck 11 in a state where there is no eccentricity, that is, the center of the substrate W coincides with the rotation center of the spin chuck 11, the region occupied by the substrate W in the image is It does not vary with the rotation of the substrate W.

  On the other hand, in the case where the substrate W is held on the spin chuck 11 in an eccentric state, that is, in a state where the center of the substrate W and the rotation center of the spin chuck 11 are shifted, the left side of FIG. 9A and FIG. As shown in FIG. 6, the area occupied by the substrate W in the captured image changes according to the rotational phase angle φ of the substrate W. In the figure, a dotted line represents an area occupied by the substrate W when the substrate W is held in a state where there is no eccentricity.

  Therefore, as shown in enlarged views on the right side in FIGS. 9A and 9B, in the partial region R3 including the peripheral edge of the substrate W in the image, the peripheral edge of the substrate W in the region R3. The position of the part changes depending on the rotational phase angle of the substrate W. If the region R3 is selected to be sufficiently small with respect to the diameter of the substrate W, the peripheral end portion of the substrate W in the region R3 can be regarded as a substantially straight line.

  Therefore, the number of pixels (shown in dark color in the drawing) corresponding to the substrate W among the pixels included in the region R3 increases or decreases according to the rotation phase angle φ of the substrate W. Such a change in the position of the peripheral edge of the substrate W due to the rotation occurs when the substrate W is held in a horizontal posture but the geometric center thereof does not coincide with the rotation center of the spin chuck 11. In addition, even when the substrate W is held on the spin chuck 11 in a tilted state, the distance from the camera 72 to the peripheral edge of the substrate W also varies periodically.

  Therefore, when the number of pixels corresponding to the substrate W among the pixels included in the region R3 is counted and the counted number of pixels is plotted against the rotation phase angle φ of the substrate W as shown in FIG. The number of pixels periodically varies with one rotation of the substrate W as a period. If the eccentricity is small, the variation in the number of pixels is small as shown by the curve A in the figure. On the other hand, as shown by the curve B, the variation in the number of pixels is large when the eccentricity is large. Therefore, an appropriate threshold value Th3 is determined in advance for the variation amount of the number of pixels, and if the variation amount of the pixel number obtained from each image captured at various rotational phase angles φ is within the threshold value Th3, the substrate W When the holding state is normal and exceeds the threshold Th3, it can be determined that the holding state is abnormal. That is, in this example, the number of pixels corresponding to the substrate W in the region R3 corresponds to the “feature amount” described above.

  As to whether the pixel included in the region R3 corresponds to the substrate W or other structure, the substrate W and other structures (specifically, the upper surface of the spin base 111) And a difference in luminance caused by a difference in distance from the camera 72. In addition, chuck pins 114 provided in contact with the periphery of the substrate W and notches (orientation flats or notches) indicating the crystal orientation of the substrate W may temporarily appear in the region R3. Thus, the number of pixels corresponding to the substrate W in the region R3 may also vary. However, while the period of variation in the number of pixels due to eccentricity corresponds to the rotation period of the substrate W, these variation factors appear only for a very short period with respect to the rotation period of the substrate W. It is possible to eliminate the influence by an appropriate filtering process.

  In detecting the peripheral edge of the substrate W, in addition to the above, for example, a method of specifying a pixel corresponding to the boundary between the substrate W and the other structure by edge extraction processing in an image is conceivable. In this case, the minimum resolution at the position of the peripheral edge is about the pixel size. On the other hand, in the above method, since the number of pixels corresponding to the substrate W included in the region R3 that also extends in the circumferential direction of the substrate W is counted, the displacement of one pixel in the radial direction of the substrate W However, the result of counting pixels is expanded to a plurality, so that the position of the peripheral edge of the substrate W can be detected with higher resolution. As a result, a margin for erroneous determination can be increased.

<Others>
As described above, in the above embodiment, the substrate 72 held on the spin chuck 11 is imaged by the camera 72, and the holding state of the substrate W is determined based on the imaging result. In each of the above-described examples shown as specific examples, the image contents of a partial region of the captured images are relatively compared among a plurality of images with different rotation phase angles of the substrate W. Specifically, in the first example, the holding state of the substrate W is determined based on the luminance fluctuation amount in the partial region R1 of the substrate W. Further, in the second example, the holding state of the substrate W is determined based on the positional fluctuation amount of the image Ia formed by reflecting the structure 92 in the processing space SP surrounded by the chamber 90 on the surface of the substrate W. Further, in the third example, the holding state of the substrate W is determined by obtaining the region occupied by the substrate W in the region R3 including the peripheral edge of the substrate W by counting the number of pixels.

  In any of these examples, the determination is made by relative comparison of image contents between a plurality of images, and since direct light components such as specular reflection light components and transmitted light components are not used, optical axis adjustment and light amount It is possible to easily and reliably determine the holding state of the substrate without requiring fine adjustment for determination such as adjustment. Further, since the detection in a state where the substrate W is rotated is possible, the holding state in the process of rotating the substrate W in order to perform the wet process without providing a special processing sequence for determination. It is possible to make a determination. For this reason, the tact time for wet processing does not decrease. In addition, by stopping rotation immediately when it is in an improper holding state, it is possible to prevent damage to the substrate and the device that may occur if rotation continues as it is, and these problems will occur It is possible to prevent the productivity from being lowered.

  As described above, in the above-described embodiment, the substrate processing system 1 or each of the substrate processing units 1A to 1D provided therein corresponds to the “substrate processing apparatus” of the present invention. In each substrate processing unit 1A and the like, the spin chuck 11 functions as the “holding unit” of the present invention, and the chuck rotating mechanism 113 and the chuck driving unit 85 function as the “rotating unit” of the present invention as a unit. . The processing space SP corresponds to the “processing space” of the present invention, and the chamber 90 functions as the “processing chamber” of the present invention.

  In the above embodiment, the illumination unit 71 functions as the “illuminating unit” of the present invention, while the camera 72 functions as the “imaging unit” of the present invention. In addition, the image processing unit 86 and the CPU 81 function as a “determination unit” of the present invention.

  Further, partial regions R1, R2, and R3 of the captured image correspond to the “comparison target region” of the present invention. The threshold values Th1, Th2, and Th3 provided corresponding to each region correspond to the “first threshold value”, “second threshold value”, and “third threshold value” of the present invention, respectively. Furthermore, in the second example, the structure 92 provided in the chamber 90 functions as the “specific part” and “position reference mark” of the present invention.

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the camera 72 stores the entire surface of the substrate W held on the spin chuck 11 within the imaging field of view, and in each of the above examples, a partial region of the substrate W is used to form the substrate W by the spin chuck 11. The holding state is determined. However, if only the holding state of the substrate is determined according to any of the above-described examples, it is not necessary to image the entire substrate, and it is sufficient if only the area necessary for the determination is captured. However, when configured to image the entire substrate W as described above, there are the following advantages. First, it is possible to execute any of the above examples with the same configuration. Therefore, it is possible to switch the determination method according to the purpose, or to determine the holding state by using a plurality of determination methods in combination. Second, an image can be used for a purpose different from the determination of the holding state. For example, the camera 72 is used for the purpose of optimizing the supply amount of the processing liquid by observing the supply state of the processing liquid to the substrate W or managing the progress of the processing while observing the state of the substrate W in real time. Images can be used.

  Moreover, in the said embodiment, although the illumination part 71 as the "illuminating means" of this invention which introduces illumination light into the process chamber (process space SP) is provided, the situation where the substrate processing system 1 was installed in the bright room Then, even if a light guide window is provided in a part of the chamber 90 and only the outside light is introduced into the processing space SP, there may be a case where a sufficient amount of illumination light can be obtained for imaging by the camera 72. In such a case, external light entering from the light guide window without providing an illumination unit (or not lighting) may be used as illumination light. In this case, the light guide window has a function as the “illuminating means” of the present invention.

  Moreover, in the said embodiment, although the illumination part 71 and the camera 72 are installed in process space SP, these at least one is installed in the exterior of the chamber 90, for example via the transparent window provided in the chamber 90 The processing space SP may be illuminated or imaged. In such a configuration, the treatment liquid is prevented from adhering to the illumination unit and the imaging unit.

  In the above embodiment, the camera 72 is provided avoiding the path of the light emitted from the illumination unit 71 and regularly reflected by the substrate W, but the regular reflected light from the substrate W does not enter the camera 72 at all. It is not essential. In other words, at least for the regions (comparison target regions) R1, R2, and R3 used for determination, it is desirable that the specularly reflected light from the regions does not enter the camera 72, but for other regions that are not used for determination, As long as the image content of the target area is not affected, the specularly reflected light from that area may be incident on the camera 72.

  Moreover, although the said embodiment applies this invention to the substrate processing system 1 which performs the wet process with respect to the board | substrate W, the process performed with respect to a board | substrate is not limited to such a wet process, but is arbitrary. That is, the present invention is applicable to various substrate processing apparatuses having a configuration for holding and rotating a substrate. Further, the substrate to be processed is not limited to a semiconductor substrate, and various substrates such as a printed wiring board and a glass substrate can be used. Further, the shape of the substrate is not limited to the circular shape as described above.

  The present invention can be applied to various substrate processing apparatuses that perform predetermined processing by rotating a substrate while holding the substrate in a horizontal posture.

1 Substrate processing system (substrate processing equipment)
1A to 1D substrate processing unit (substrate processing apparatus)
11 Spin chuck (holding means)
71 Illumination part (illumination means)
72 Camera (imaging means)
81 CPU (determination means)
85 Chuck drive (rotating means)
86 Image processing unit (determination means)
90 chamber (processing room)
92 Structures (specific parts, position reference marks)
111 Spin base 113 Chuck rotating mechanism (rotating means)
114 Chuck pins R1, R2, R3 Comparison target area SP Processing space Th1 First threshold Th2 Second threshold Th3 Third threshold W Substrate

Claims (16)

Holding means for holding the substrate in a substantially horizontal position;
Rotating means for rotating the holding means about a substantially vertical axis;
A processing chamber for forming a processing space for accommodating the holding means;
Illumination means for introducing illumination light into the processing chamber;
Imaging means for imaging the substrate held by the holding means;
From the image captured by the imaging unit, an image including at least a part of the surface of the substrate that does not include the regular reflection image of the illumination unit is used as a comparison target region, and images are captured with different rotational phase angles of the substrate. A substrate processing apparatus comprising: a determination unit that determines a holding state of the substrate by the holding unit based on a comparison result of image contents of the comparison target region between a plurality of images.   The substrate processing apparatus according to claim 1, wherein the determination unit determines the holding state based on a comparison result of luminance of the comparison target area between the plurality of images.   The determination unit determines that the holding state is normal if a difference in luminance value between the highest and lowest luminances of the comparison target region among the plurality of images is within a predetermined first threshold. The substrate processing apparatus according to claim 1, wherein the holding state is determined to be abnormal when the difference between the luminance values exceeds the first threshold.   The determination means includes a difference between a sum of pixel values of pixels included in the comparison target area in one image and a sum of pixel values of pixels included in the comparison target area in the other image. The substrate processing apparatus according to claim 2, wherein is a difference in the luminance value between the two images. The imaging means captures an image including an image of a specific part in the processing chamber reflected on the surface of the substrate;
The determination means sets the holding state based on a comparison result of the position of the image of the specific part between the plurality of images, with an area including the image of the specific part of the imaged substrate surface as the comparison target area. The substrate processing apparatus of Claim 1 which determines.   The determination unit holds in advance information related to the position of the image of the specific part on the substrate that is normally held by the holding unit, and the position specified by the information and the specification in each of the plurality of images If the amount of positional deviation from the position of the image of the part is within a predetermined second threshold, it is determined that the holding state is normal, while if the amount of positional deviation exceeds the second threshold, the holding state is The substrate processing apparatus according to claim 5, wherein the substrate processing apparatus is determined to be abnormal.   The determination unit determines that the holding state is normal if the maximum value of the relative positional shift amount of the image of the specific part between the plurality of images is within a predetermined third threshold, The substrate processing apparatus according to claim 5, wherein the holding state is determined to be abnormal when a deviation amount exceeds the third threshold value.   The substrate processing apparatus according to claim 5, wherein a position reference mark that functions as the specific part is provided at a position facing the substrate surface in the processing chamber.   The comparison target region includes a part of a peripheral edge of the substrate, and the determination unit compares the size of the area occupied by the substrate in the comparison target region between the plurality of images, and determines the holding state. The substrate processing apparatus of Claim 1 which determines.   If the area difference between the highest area and the lowest area of the substrate occupying the comparison target region among the plurality of images is within a predetermined fourth threshold, the determination unit determines that the holding state is The substrate processing apparatus according to claim 9, wherein the substrate processing apparatus determines that the holding state is abnormal when the area difference exceeds the fourth threshold while determining that the area is normal.   The substrate processing apparatus according to claim 9, wherein the determination unit sets the number of pixels corresponding to the substrate among the pixels included in the comparison target region as an area of the substrate occupying the comparison target region.   The substrate processing apparatus according to claim 1, wherein the imaging unit is disposed in a position where regular reflection light of the illumination light from the substrate surface is not incident in the processing chamber. Holding the substrate in a holding means for holding the substrate in a substantially horizontal position in the processing chamber;
Illuminating the substrate with illumination means;
Imaging a plurality of images of the substrate held by the holding means with different rotational phase angles around the vertical axis of the substrate;
For each of the plurality of captured images, a region including at least a part of the substrate surface that does not include the specularly reflected light component of illumination light is set as a comparison target region, and the image of the comparison target region between the plurality of images. And a step of determining a holding state of the substrate by the holding unit based on a comparison result of contents.   The substrate processing method according to claim 13, wherein the holding state is determined based on a luminance comparison result of the comparison target region between the plurality of images. Each of the plurality of images includes an image of a specific part in the processing chamber reflected on the surface of the substrate,
14. The holding state is determined based on a comparison result of the position of the image of the specific part between the plurality of images, with an area including the image of the specific part of the imaged substrate surface as the comparison target area. The substrate processing method as described in 2. above.   The comparison target region includes a part of a peripheral edge portion of the substrate, and the holding state is determined by comparing the size of the area occupied by the substrate in the comparison target region between the plurality of images. The substrate processing method as described in 2. above.

Images