Substrate edge detection method

Abstract

To obtain an edge position of a substrate with high accuracy from a captured image including a peripheral portion of the substrate and a background of the peripheral portion even when imaging is performed particularly under a bright background.SOLUTION: A substrate edge detection method includes, a step of acquiring correction data for an edge position for an exposure time in a saturated section where brightness of a background image is saturated with respect to a change in the exposure time in imaging processing, before the edge position is detected, and a step of correcting an actual edge position detected on the basis of an image obtained by imaging processing in the saturated section in an adjacent direction according to the correction data corresponding to the exposure time in the imaging processing and setting the corrected position as the edge position. As a result, when an image is obtained by the imaging processing in the saturated section, the actual edge position detected on the basis of the image is corrected with the correction data, whereby the detection of the edge position is made more accurate.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present invention relates to a technique for detecting the edge position of a substrate, such as a semiconductor wafer, from an image obtained by imaging the peripheral portion of the substrate. [Background technology]

[0002] There are known processing systems that perform various processes on the peripheral portion of an object to be imaged, such as a semiconductor wafer. In such substrate processing systems, for example, in order to monitor the processing state, the substrate to be processed is illuminated and an image is taken by an image taking device such as a CCD camera. The peripheral portion of the substrate may have various shapes, for example, a substrate having a bevel portion formed by polishing the surface to make it an inclined surface.

[0003] For the purpose of observing the finish state of the bevel portion of such a substrate, it is possible to apply a combination of the imaging means described above and an image processing technique for the image obtained by imaging. For example, Patent Document 1 discloses a substrate processing apparatus in which the peripheral portion, including the bevel portion, of a wafer (substrate) having a plurality of films laminated on its surface is evaluated by imaging and image processing. In this technique, the edge position of each film is detected from the image, and it is evaluated whether or not the film has been removed from the edge of the wafer by a desired WEE (Wafer Edge Exclusion) width in the bevel portion. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-144102 A (for example, paragraph 0157) Summary of the Invention [Problem to be solved by the invention]

[0005] In the substrate processing system, the wafer is also inspected for defects on the periphery based on the image. When it is necessary to improve the signal-to-noise ratio of the image for this defect inspection, the exposure time of the imaging means is increased, for example. This may cause the brightness of the area (background image) outside the wafer edge in the image to saturate, resulting in so-called whiteout. In this case, the brightness of the background image in the image does not necessarily represent the actual brightness. In reality, as will be described later in detail, the edge position actually measured based on the image (hereinafter referred to as the "actual edge position") is calculated to be located inside the actual edge position of the substrate (hereinafter referred to as the "true edge position"). As a result, the WEE width is calculated to be shorter than it actually is.

[0006] The present invention has been made in consideration of the above-mentioned problems, and aims to determine the edge position of a substrate with high accuracy from an image captured including the peripheral portion of the substrate and the background of the peripheral portion, even when the background is captured in a bright state. [Means for solving the problem]

[0007] This invention is a substrate edge detection method for detecting an edge position of a substrate from an image including a peripheral image corresponding to the peripheral portion and a background image corresponding to the background obtained by an imaging process that images the peripheral portion of the substrate and an adjacent portion adjacent in a predetermined adjacent direction where a background with higher brightness than the peripheral portion is adjacent, and is characterized by comprising the steps of: (a) prior to detecting the edge position, acquiring correction data for the edge position with respect to exposure time in a saturation section in which the brightness of the background image is saturated with respect to changes in exposure time in the imaging process; and (b) determining the edge position as a position obtained by correcting the actual edge position detected based on the image obtained by the imaging process within the saturation section in the adjacent direction in accordance with the correction data corresponding to the exposure time in the imaging process.

[0008] When the exposure time is increased to the extent that the brightness of the background image is saturated, the brightness of the peripheral image in the saturated section becomes higher than the value reflecting the actual brightness, as shown in FIG. 11 described later. Therefore, the measured edge position shifts to the inside of the substrate. Therefore, in the present invention, correction data is acquired in advance for the exposure time in the saturated section to correct the shift in the edge position that occurs when the imaging process is performed with the exposure time. Then, when an image is obtained by the imaging process within the saturated section, the measured edge position detected based on the image is corrected with the correction data, and the detection of the edge position is made more accurate. Effect of the Invention

[0009] According to this invention, even if the brightness of the background image is saturated, the edge position of the substrate can be found with high accuracy from the image obtained by the imaging process. [Brief description of the drawings]

[0010] [Figure 1] 1 is a diagram showing a substrate processing system equipped with an example of a substrate processing apparatus to which a substrate edge detection method according to the present invention can be applied; [Diagram 2] FIG. 1 is a diagram illustrating a schematic configuration of a substrate processing apparatus. [Diagram 3] 2 is a plan view of a portion of the substrate processing apparatus as viewed from above. FIG. [Figure 4] 1 is a diagram illustrating an example of the shape of a peripheral portion of a substrate to be imaged; [Diagram 5] 4 is a block diagram showing an electrical configuration of the substrate processing apparatus shown in FIGS. 2 and 3. FIG. [Figure 6] FIG. 2 is a perspective view showing a head portion of the imaging mechanism. [Figure 7] FIG. 2 is a diagram illustrating a typical progression of light that contributes to top-side imaging. [Figure 8] FIG. 13 is a diagram illustrating a typical progression of light that contributes to side imaging. [Figure 9] 4 is a diagram showing a schematic image of a peripheral portion of a substrate captured by an imaging section; FIG. [Figure 10]FIG. 2 is a diagram showing an edge inspection image and a luminance distribution of the image. [Figure 11] 11 is a graph showing the relationship between the exposure time in the imaging process and the brightness and edge position of the background image. [Figure 12] 3 is a flowchart showing a substrate processing carried out in the substrate processing apparatus shown in FIG. [Figure 13] 13 is a flowchart showing a correction table acquisition process. [Figure 14] 4 is a flowchart showing an edge detection process which is one embodiment of a substrate edge detection method according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] 1 is a diagram showing a substrate processing system equipped with an example of a substrate processing apparatus to which the substrate edge detection method according to the present invention can be applied. The substrate processing system 200 includes a substrate processing section 210 that processes a substrate S, and an indexer section 220 that is coupled to the substrate processing section 210. The indexer section 220 includes a container holding section 221 that can hold a plurality of containers C (FOUP (Front Opening Unified Pod), SMIF (Standard Mechanical Interface) pod, OC (Open Cassette), etc. that contain a plurality of substrates S in a sealed state) for containing the substrates S, and an indexer robot 222 that accesses the container C held by the container holding section 221 to take out an unprocessed substrate S from the container C or store a processed substrate S in the container C. Each container C contains a plurality of substrates S in a substantially horizontal position.

[0012] In this specification, the pattern-formed surface (one main surface) of both main surfaces of the substrate S on which a pattern is formed is referred to as the "front surface," and the other main surface on the opposite side on which no pattern is formed is referred to as the "rear surface." The surface facing downward is referred to as the "lower surface," and the surface facing upward is referred to as the "upper surface." In this specification, the "pattern-formed surface" refers to the surface of the substrate on which a concave-convex pattern is formed in any region.

[0013] The indexer robot 222 comprises a base 222a fixed to the device housing, an articulated arm 222b rotatably provided around a vertical axis relative to the base 222a, and a hand 222c attached to the tip of the articulated arm 222b. The hand 222c is structured so that a substrate S can be placed on its upper surface and held thereon. Indexer robots having such articulated arms and hands for holding substrates are well known, and therefore detailed description thereof will be omitted.

[0014] The substrate processing section 210 includes a substrate transfer robot 211 disposed approximately at the center in a plan view, and a plurality of processing units 1 disposed to surround the substrate transfer robot 211. Specifically, the plurality of processing units 1 are disposed facing the space in which the substrate transfer robot 211 is disposed. The main components of the processing units 1 are installed inside the processing chamber 100. The substrate transfer robot 211 accesses these processing units 1 at appropriate times to transfer the substrate S. Meanwhile, each processing unit 1 performs a predetermined process on the substrate S. In this embodiment, one of these processing units 1 corresponds to the substrate processing apparatus according to the present invention.

[0015] FIG. 2 is a diagram showing a schematic configuration of a substrate processing apparatus. FIG. 3 is a plan view of a part of the substrate processing apparatus seen from above. FIG. 4 is a diagram showing an example of the shape of the peripheral portion of a substrate to be imaged. FIG. 5 is a block diagram showing an electrical configuration of the substrate processing apparatus shown in FIGS. 2 and 3. In FIGS. 2, 3 and each of the figures referred to below, the dimensions and numbers of each part may be exaggerated or simplified for ease of understanding. In addition, in order to clarify the directional relationships, each figure is appropriately provided with a coordinate system in which the Z axis is the vertical direction and the XY plane is the horizontal plane.

[0016] The substrate processing apparatus (processing unit) 1 includes a rotation mechanism 2, a scattering prevention mechanism 3, a processing mechanism 4, a peripheral heating mechanism 5, and an imaging mechanism 6. These components 2 to 6 are housed in an internal space 101 of a processing chamber 100 and are electrically connected to a control unit 9 that controls the entire apparatus. The components 2 to 6 operate in response to instructions from the control unit 9.

[0017] The control unit 9 may be, for example, a device similar to a general computer. That is, in the control unit 9, a CPU serving as an arithmetic processing unit 91 performs arithmetic processing according to a procedure described in a program, thereby controlling each part of the substrate processing apparatus 1. As a result, the substrate processing apparatus 1 supplies a processing liquid to the peripheral part of the upper surface of the substrate S in the processing chamber to perform a bevel etching process. The detailed configuration and operation of the control unit 9 will be described later. In this embodiment, the control unit 9 is provided for each substrate processing apparatus 1, but a configuration may be adopted in which a single control unit controls a plurality of substrate processing apparatuses 1. In addition, a configuration may be adopted in which the substrate processing apparatus 1 is controlled by a control unit (not shown) that controls the entire substrate processing system 200.

[0018] The rotation mechanism 2 rotates the substrate S in a rotation direction AR1 (FIG. 3) while holding it in a substantially horizontal position with its surface facing upward. The rotation mechanism 2 rotates the substrate S around a vertical rotation axis AX passing through the center of the main surface of the substrate S. The rotation mechanism 2 includes a spin chuck 21, which is a disk-shaped member smaller than the substrate S. The spin chuck 21 is provided so that its upper surface is substantially horizontal and its central axis coincides with the rotation axis AX. A rotation shaft portion 22 is connected to the lower surface of the spin chuck 21. The rotation shaft portion 22 extends in the vertical direction with its axis line coinciding with the rotation axis AX. A rotation drive portion (e.g., a motor) 23 is connected to the rotation shaft portion 22. The rotation drive portion 23 drives the rotation shaft portion 22 to rotate around its axis line in response to a rotation command from the control unit 9. Therefore, the spin chuck 21 can rotate around the rotation axis AX together with the rotation shaft portion 22. The rotation drive unit 23 and the rotation shaft unit 22 function to rotate the spin chuck 21 about the rotation axis AX.

[0019] A through hole (not shown) is provided in the center of the spin chuck 21, and communicates with the internal space of the rotating shaft portion 22. A pump 24 (FIG. 5) is connected to the internal space through a pipe in which a valve (not shown) is interposed. The pump 24 and the valve are electrically connected to the control unit 9 and operate according to commands from the control unit 9. This allows negative pressure and positive pressure to be selectively applied to the spin chuck 21. For example, when the pump 24 applies negative pressure to the spin chuck 21 with the substrate S placed on the upper surface of the spin chuck 21 in a substantially horizontal position, the spin chuck 21 sucks and holds the substrate S from below. On the other hand, when the pump 24 applies positive pressure to the spin chuck 21, the substrate S can be removed from the upper surface of the spin chuck 21. When the suction of the pump 24 is stopped, the substrate S can be moved horizontally on the upper surface of the spin chuck 21.

[0020] As shown in Fig. 3, the splash prevention mechanism 3 has a generally cylindrical cup 31 provided to surround the outer periphery of the substrate S held by the spin chuck 21, and a liquid receiving portion 32 provided below the outer periphery of the cup 31. The cup 31 is raised and lowered by the operation of a guard driving portion 33 (Fig. 5) in response to a control command from the control unit 9. When the cup 31 is positioned at the lower position, the upper end of the cup 31 is located below the peripheral portion Ss of the substrate S held by the spin chuck 21, as shown in Fig. 2. Conversely, when the cup 31 is positioned at the upper position, the upper end of the cup 31 is located above the peripheral portion Ss of the substrate S.

[0021] 2, when the cup 31 is in the lower position, the substrate S held by the spin chuck 21 is exposed to the outside of the cup 31. This prevents the cup 31 from becoming an obstacle, for example, when the substrate S is loaded onto or unloaded from the spin chuck 21.

[0022] On the other hand, when the cup 31 is in the upper position, the inner peripheral surface of the cup 31 surrounds the outer periphery of the substrate S held by the spin chuck 21. This makes it possible to prevent droplets of the processing liquid shaken off from the peripheral portion Ss of the substrate S from scattering inside the processing chamber 100 during the bevel etching process described below. It also makes it possible to reliably recover the processing liquid. That is, as the substrate S rotates, droplets of the processing liquid shaken off from the peripheral portion Ss of the substrate S adhere to the inner peripheral surface of the cup 31 and flow downward, and are collected and recovered by the liquid receiving portion 32 arranged below the cup 31.

[0023] The processing mechanism 4 has a base 41, a rotating support shaft 42, an arm 43, and a processing liquid nozzle 44. The base 41 is fixed to the processing chamber 100. The rotating support shaft 42 is provided rotatably relative to the base 41. The arm 43 extends horizontally from the rotating support shaft 42, and a processing liquid nozzle 44 is attached to its tip. The rotating support shaft 42 rotates in response to a control command from the control unit 9, causing the arm 43 to swing, and the processing liquid nozzle 44 at the tip of the arm 43 moves between a retracted position retracted from above the substrate S to the side and a processing position above the peripheral portion of the substrate S. In FIG. 3, the nozzle 44 indicated by the two-dot chain line is in the retracted position, and the nozzle 44 indicated by the solid line is in the processing position.

[0024] The processing liquid nozzle 44 is connected to a processing liquid supply unit 45 (FIG. 5). When the processing liquid supply unit 45 supplies the processing liquid toward the processing liquid nozzle 44 in response to a supply command from the control unit 9, the processing liquid is discharged from the processing liquid nozzle 44 toward a processing start position Ps. This processing start position Ps is a point on the path along which the peripheral portion Ss of the substrate S moves. Therefore, as the processing liquid nozzle 44 discharges the processing liquid while the spin chuck 21 rotates, each portion of the peripheral portion Ss of the substrate S is supplied with the processing liquid while passing through the processing start position Ps. As a result, a bevel etching process using the processing liquid is performed on the entire peripheral portion Ss of the substrate S.

[0025] The peripheral heating mechanism 5 includes an annular heater 51. The heater 51 incorporates a heating element that extends in the peripheral direction of the substrate S along the peripheral portion of the lower surface of the substrate S. When a heating command is given to the heater 51 from the control unit 9, the peripheral portion Ss of the substrate S is heated from below by heat emitted from the heating element. This raises the temperature of the peripheral portion Ss to a value suitable for the bevel etching process.

[0026] The imaging mechanism 6 includes a base 6A, a pivot 6B, an arm 6C, a head driver 6D, an illumination optical system 6E, an observation optical system 6F, and a head 6G. The base 6A is fixed to the processing chamber 100. The pivot 6B is rotatably provided on the base 6A. An arm 6C extends horizontally from the pivot 6B, and a head 6G is attached to its tip. When a control command is given from the control unit 9 to the head driver 6D (FIG. 5) that drives the arm 6C, the head driver 6D swings the arm 6C as shown by the dashed line in FIG. 3 in response to the command. As a result, the head 6G attached to the tip of the arm 6C reciprocates between a retreat position P1 where the head 6G retreats from above the substrate S to the side, and an imaging position P2 where the head 6G captures an image of the peripheral portion Ss of the substrate S. 3, the head unit 6G indicated by a solid line is in the retracted position, and the head unit 6G indicated by a dashed line is in the imaging position. At the imaging position P2, the head unit 6G is disposed close to the (-Y) side end of the substrate S.

[0027] As shown in FIG. 3, the illumination optical system 6E and the observation optical system 6F are provided at a position P3 spaced from the imaging position P2 in the X direction. This position P3 is spaced from each unit (the rotation mechanism 2, the scattering prevention mechanism 3, the processing mechanism 4, and the peripheral heating mechanism 5) that performs the bevel etching process on the substrate S and the cup 31. The illumination optical system 6E irradiates the illumination light L1 from the outside of the cup 31 toward the imaging position P2. At this time, the cup 31 is positioned at a lower position, and the head unit 6G is positioned at the imaging position P2, so that the illumination light L1 is incident on the head unit 6G. The illumination light L1 is diffusely reflected by the head unit 6G. The diffused light thus generated illuminates the peripheral portion Ss of the substrate S. Then, the reflected light L2 reflected by the peripheral portion Ss of the substrate S is further reflected by the head unit 6G. The reflected light L2 is guided from the head unit 6G toward the position P3 and incident on the observation optical system 6F. As a result, the observation optical system 6F acquires an image of the peripheral portion Ss of the substrate S, and sends the image data to the control unit 9.

[0028] Here, the peripheral portion Ss of the substrate S to be imaged in this embodiment will be described with reference to Fig. 4. As shown in Fig. 4, some substrates S, such as semiconductor wafers, have a bevel portion having an inclined surface formed on their peripheral portion. The "bevel portion" here refers to the entire area of ​​the peripheral portion Ss of the substrate S, whose surface is inclined with respect to the horizontal plane when the substrate S is in a horizontal position.

[0029] The cross-sectional shape and dimensions of the bevel are specified as standard specifications, with the maximum dimension Dmax shown by the dotted line and the minimum dimension Dmin shown by the dashed line, and generally a relatively high degree of freedom is given as long as they fall within these limits. In many cases, the cross section of the bevel is made up of multiple surfaces with different inclinations, as shown in Figure 4, but there are also cases where it is made up of a curved surface.

[0030] In the following, where necessary, the portion of the peripheral portion Ss of the substrate S that is flush with the upper surface of the substrate S will be referred to as the "A surface" and given the symbol Sa, and the edge surface of the substrate S will be referred to as the "C surface" and given the symbol Sc. The inclined surface connecting the A surface Sa and the C surface Sc will be referred to as the "B surface" and given the symbol Sb. The portion that is flush with the lower surface of the substrate S will be referred to as the "E surface" and given the symbol Se, and the inclined surface connecting the C surface Sc and the E surface Se will be referred to as the "D surface" and given the symbol Sd. In this specification, the "periphery portion Ss" is a concept that comprehensively includes each of these surfaces.

[0031] As described above, the head unit 6G has both a diffusion illumination function of receiving illumination light L1 from the illumination optical system 6E to generate diffuse light and illuminating the peripheral portion Ss of the substrate S with the diffuse light, and a guide function of guiding reflected light L2 reflected by the peripheral portion Ss to the observation optical system 6F. The configuration and operation of the head unit 6G will be described below with reference to Figures 6 to 9. After that, the configuration and operation of the illumination optical system 6E will be described in detail.

[0032] Fig. 6 is a perspective view showing the head part of the imaging mechanism. More specifically, Fig. 6(a) is a diagram showing a state where the head part 6G is placed at the imaging position P2, and Fig. 6(b) shows a state where the substrate S is removed from the head part 6G. The head part 6G has a diffuse illumination part 61 having a diffuse surface 610, a guide part 62 composed of three mirror members 62a to 62c each surrounded by the diffuse surface 610, and a holding part 63 that holds the diffuse illumination part 61. In Fig. 6, a dot is added to the area corresponding to the holding part 63 to distinguish it from the diffuse illumination part 61.

[0033] The diffuse lighting section 61 is made of a white fluorine-based resin, for example, PTFE (polytetrafluoroethylene). The diffuse lighting section 61 has a plate shape that is approximately parallel to the YZ plane, and a notch 611 is formed at the end on the (+Y) direction side. This notch 611 has a shape obtained by rotating a U-shape 90° clockwise when viewed from the (+X) direction side.

[0034] In the diffuse illumination section 61, an inclined surface 610 is provided along the cutout portion 611. The inclined surface 610 is provided so as to surround the cutout portion 611 from the top and bottom directions and the (-Y) direction, and is a tapered surface that is finished so as to incline in the (-X) direction as it approaches the cutout portion 611. The surface is finished so as to diffusely reflect incident light, and as will be described later, functions as a diffusion surface 610 that diffusely reflects the illumination light and causes it to be incident on the peripheral portion Ss of the substrate S.

[0035] Mirror members 62a to 62c are attached so as to be surrounded by diffusion surface 610. More specifically, a first mirror member 62a is attached to a position on diffusion surface 610 vertically above notch 611, a second mirror member 62b is attached to the (-Y) side of notch 611, and a third mirror member 62c is attached to a position vertically below notch 611. In this embodiment, mirror members 62a to 62c are made of Si (silicon) in consideration of chemical resistance, heat resistance, and the like.

[0036] On the other hand, the holding unit 63 is made of a resin having high resistance to chemicals and heat, such as PEEK (polyetheretherketone), and is a plate-like member having an outer shape generally similar to that of the diffuse illumination unit 61. The holding unit 63 is connected to the rear surface of the diffuse illumination unit 61, that is, the (-X) side main surface, and functions as a backup member. The holding unit 63 is also connected to the arm 6C. Therefore, the oscillating motion of the arm 6C causes the diffuse illumination unit 61 and the holding unit 63 to move integrally between the retracted position P1 and the imaging position P2.

[0037] As shown in FIG. 6(a), when the head unit 6G is at the imaging position P2 and the substrate S is held by the spin chuck 21, the peripheral portion Ss of the substrate S is positioned between the notches 611. When the notches 611 are viewed from the (+X) side in the (-X) direction, the first mirror member 62a reflects the images of the portions of the substrate peripheral portion Ss that are visible when viewed from above, that is, the A-side Sa and the B-side Sb. Similarly, the second mirror member 62b reflects the images of the portions of the substrate peripheral portion Ss that are visible when viewed from the side, that is, the B-side Sb, the C-side Sc, and the D-side Sd. Moreover, the third mirror member 62c reflects the images of the portions of the substrate peripheral portion Ss that are visible when viewed from below, that is, the D-side Sd and the E-side Se.

[0038] As will be described in detail later, the observation optical system 6F captures images in an imaging field set to view all three mirror members 62a-62c from the (+X) side. As a result, the images of the substrate S reflected in each of the mirror members 62a-62c are captured in a single image. That is, the observation optical system 6F can capture images of the A-side Sa, B-side Sb, C-side Sc, D-side Sd, and E-side Se of the substrate Ss all in a single image. By capturing images multiple times as the substrate S rotates, images of multiple regions of the peripheral portion Ss at different positions along the circumferential direction can be obtained.

[0039] In the following description, capturing images of the A-surface Sa and B-surface Sb of the substrate S reflected in the first mirror member 62a is referred to as "top surface imaging." Capturing images of the B-surface Sb, C-surface Sc, and D-surface Sd of the substrate S reflected in the second mirror member 62b is referred to as "side surface imaging." Capturing images of the D-surface Sd and E-surface Se of the substrate S reflected in the third mirror member 62c is referred to as "bottom surface imaging."

[0040] FIG. 7 is a diagram showing a typical way in which light that contributes to imaging of the upper surface travels. More specifically, FIG. 7(a) is a perspective view showing the path of light that is incident on and reflected by the head unit 6G, and FIG. 7(b) is a cross-sectional view of the vertical cut surface thereof. As shown by solid arrows in FIG. 7(a) and FIG. 7(b), illumination light L1a traveling in the (-X) direction along the upper surface side of the substrate S is incident on the diffusion surface 610 of the head unit 6G. The light that is incident on the diffusion surface 610, particularly on the upper diffusion surface 61a located above the cutout portion 611, and diffusely reflected is incident on the upper surface of the substrate S from various directions, thereby illuminating the substrate peripheral portion Ss.

[0041] As indicated by the dotted arrows, the light reflected by the substrate S can travel in various directions, but among these, the light L2a that is incident on the mirror member 62a and is reflected by the mirror member 62a and travels in the (+X) direction is incident on the observation optical system 6F arranged on the optical path. By receiving this light, "top surface imaging" is realized, which images the peripheral portion Ss of the substrate S as viewed from the top surface side.

[0042] 7(b), a phenomenon similar to that on the upper surface side occurs on the lower surface side of the substrate S. That is, the head unit 6G has a top-bottom symmetrical structure, and illumination light L1c traveling in the (-X) direction along the lower surface side of the substrate S is incident on the lower diffusion surface 61c located particularly below the cutout portion 611 of the diffusion surface 610, and is diffusely reflected thereon to illuminate the lower surface of the substrate S. At this time, reflected light L2c reflected by the substrate S and the mirror member 62c and traveling in the (+X) direction is received, thereby achieving "lower surface imaging" that images the peripheral portion Ss as viewed from the lower surface side of the substrate S.

[0043] FIG. 8 is a diagram showing a schematic diagram of the progression of light that contributes to side imaging. More specifically, FIG. 8(a) is a perspective view showing the path of light that is incident on and reflected by the head unit 6G, and FIG. 8(b) is a cross-sectional view of the horizontal cut surface thereof. As shown by the solid arrows in FIG. 8(a) and FIG. 8(b), the illumination light L1b traveling in the (-X) direction along the side of the substrate S is incident on the diffusion surface 610 of the head unit 6G, and is diffusely reflected by the lateral diffusion surface 61b located on the side of the cutout portion 611 in particular. This light is incident on the side of the substrate S from various directions, thereby illuminating the substrate peripheral portion Ss.

[0044] Among the light reflected from the substrate S indicated by the dotted arrow, light L2b reflected by the mirror member 62b and traveling in the (+X) direction is incident on the observation optical system 6F arranged on the optical path. This realizes "side surface imaging" for imaging the peripheral portion Ss of the substrate S as viewed from the side.

[0045] The observation optical system 6F has an observation lens system composed of an object-side telecentric lens and a CMOS camera. Therefore, only the reflected light L2 (L2a, L2b, L2c) parallel to the optical axis of the observation lens system among the above reflected light is incident on the sensor surface of the CMOS camera, and an image of the peripheral portion Ss of the substrate S and the adjacent area is formed on the sensor surface. In this way, the observation optical system 6F captures the peripheral portion Ss of the substrate S and the adjacent area, and obtains an image Im including, for example, an upper surface image area Ma, a side surface image area Mb, and a lower surface image area Mc as shown in FIG. Then, the observation optical system 6F transmits image data indicating the image to the control unit 9.

[0046] 9A and 9B are diagrams showing an image of the peripheral portion of the substrate captured by the imaging unit. Fig. 9A is a schematic diagram showing the head unit 6G and the substrate S viewed from the (+X) side in the (-X) direction, and the area FV surrounded by a dashed line represents the imaging field of view of the observation optical system 6F. In this way, the imaging field of view FV of the observation optical system 6F is set to include the mirror members 62a to 62c of the head unit 6G.

[0047] Fig. 9(b) shows a schematic diagram of images of the substrate S reflected on the mirror members 62a to 62c within the imaging field of view FV. As shown in Fig. 9(b), images of the A-side Sa and B-side Sb of the peripheral portion Ss of the substrate S are reflected on the first mirror member 62a. Images of the B-side Sb, C-side Sc, and D-side Sd of the peripheral portion Ss of the substrate S are reflected on the second mirror member 62b. Images of the D-side Sd and E-side Se of the peripheral portion Ss of the substrate S are reflected on the third mirror member 62c. The observation optical system 6F captures these images collectively to obtain one image.

[0048] Fig. 9(c) is a schematic diagram of an image actually obtained by imaging. In the imaging mechanism 6 configured as described above, the illumination light from the illumination optical system 6E is diffused by the diffusion surface 610 to illuminate the substrate S, and an image is captured by receiving a portion of the reflected light from the substrate S. For this reason, it cannot be said that either the illumination light amount or the received light amount is sufficient. In order to capture an image satisfactorily under such circumstances, it is necessary to increase the sensitivity of the camera, and as a result, the detailed structure of the head part 6G is hardly reflected in the image due to so-called overexposure.

[0049] Therefore, as shown in Figure 9 (c), the image Im actually obtained includes a dark region Md corresponding to the cutout portion 611 and including an image of the side of the substrate S that is reflected out of focus within it, a top image region Ma corresponding to the image of the peripheral portion Ss of the substrate S viewed from above, a side image region Mb corresponding to the image of the peripheral portion Ss of the substrate S viewed from the side, and a bottom image region Mc corresponding to the image of the peripheral portion Ss of the substrate S viewed from below.

[0050] By analyzing the image Im including these regions, it is possible to obtain information indicating the shape of the peripheral portion of the substrate S in the circumferential direction, the etching state, etc. From this information, it is possible to inspect the amount of eccentricity of the substrate S placed on the spin chuck 21 with respect to the rotation axis AX, the amount of warping of the substrate S, the bevel etching result (EEW ​​width), etc.

[0051] In the substrate processing apparatus 1 equipped with the imaging mechanism 6 configured as described above, the control unit 9 controls each part of the apparatus to execute (A) substrate inspection before bevel etching, (B) alignment, (C) bevel etching after alignment, and (D) substrate inspection after bevel etching. As shown in Fig. 5, the control unit 9 has a calculation processing unit 91 that performs various calculation processes, a storage unit 92 that stores basic programs and image data, and an input display unit 93 that displays various information and receives input from an operator.

[0052] In the control unit 9, a calculation processor (CPU) 91 as a main control unit performs calculation processing according to a procedure described in a program, thereby controlling each part of the substrate processing apparatus 1 as follows. That is, as shown in Fig. 5, the calculation processor 91 functions as a positioning control unit 911 that performs positioning of the head unit 6G, an entire peripheral image acquisition unit 912 that acquires an entire peripheral image, an eccentricity amount derivation unit 913 that derives an amount of eccentricity of the substrate S from the entire peripheral image before the bevel etching process, a warpage amount derivation unit 914 that derives an amount of warpage of the substrate S from the entire peripheral image before the bevel etching process, an etching width derivation unit 915 that derives an etching width from the entire peripheral image after the bevel etching process, and a residue analysis unit 916 that analyzes residues from a residue-enhanced image obtained by image processing the entire peripheral image.

[0053] 5 denotes an eccentricity correction mechanism that moves the substrate S by the amount of eccentricity described above to correct the eccentricity of the substrate S with respect to the rotation axis AX. Since a conventionally known eccentricity correction mechanism can be used, a detailed description of the structure of the eccentricity correction mechanism 7 will be omitted here.

[0054] The illumination optical system 6E of the imaging mechanism 6 irradiates an area FV (see FIG. 9(a)) including a diffusion surface 610 with illumination light L1 as primary illumination light, thereby generating diffuse light that is diffusely reflected by the diffusion surface 610 as secondary illumination light. The substrate S is then illuminated by this diffuse light (illumination process). Moreover, the observation optical system 6F of the imaging mechanism 6 receives a portion of the reflected light from the substrate S, thereby imaging the peripheral portion Ss of the substrate S. In this manner, the peripheral portion Ss is observed by the observation optical system 6F (observation process).

[0055] Here, in order to inspect the WEE width in particular, an image including the outer side of the peripheral edge Ss and the C-face Sc of the substrate S (FIG. 4), i.e., the background of the substrate S (e.g., the area surrounded by the thick dotted line in FIG. 9(c)) is acquired by imaging processing using the imaging mechanism 6. Hereinafter, for ease of explanation, this image is referred to as the "edge inspection image Me."

[0056] FIG. 10 is a diagram showing an edge inspection image and a luminance distribution of the image. Here, the substrate processing apparatus 1 performs bevel etching on the substrate S on the surface of which a film to be etched (not shown) is formed. The upper part of FIG. 10 shows an edge inspection image Me obtained by imaging the substrate S using the imaging mechanism 6. The edge inspection image Me includes a peripheral image IM1 corresponding to the peripheral portion Ss of the upper surface of the substrate S and a background image IM2 corresponding to the background of the substrate S. Looking at the peripheral image IM1 in more detail, the peripheral image IM1 is composed of an image IMf of the film to be etched remaining after the bevel etching, an image IMa of the A surface Sa, and an image IMb of the B surface Sb. The boundary between the peripheral image IM1 and the background image IM2 corresponds to the measured edge position Pse, and the boundary between the image IMf and the image IMa corresponds to the etching boundary Pb. Furthermore, the distance between the measured edge position Pse and the etching boundary Pb in the radial direction RD (corresponding to the adjacent direction of the present invention) of the substrate S corresponds to the WEE width. In the figure, the symbol Pie indicates the image edge on the background side in the edge inspection image Me.

[0057] The lower part of the figure shows a graph showing the luminance distribution of the edge inspection image Me along the radial direction RD. In this graph, the horizontal axis indicates the position away from the image edge Pie toward the center of the substrate S, and the vertical axis indicates the luminance of the edge inspection image Me at each position in 256 gradations. In this graph, the luminance drops sharply at the boundary between the background image IM2 and the peripheral image IM1. In other words, the peripheral portion Ss of the substrate S and the background, which is brighter than the peripheral portion Ss, are adjacent in the radial direction RD, and these correspond to an example of the "adjacent portion" of the present invention. In this embodiment, if the upper and lower limits of the luminance range occurring in this adjacent portion are "Iemax" and "Iemin", respectively, then the following equation can be used: Ie=(Iemax-Iemin) / 2 The edge luminance Ie is calculated based on the edge luminance Ie. The position corresponding to the edge luminance Ie is determined as the measured edge position Pse of the substrate S. Of course, the method of determining the measured edge position Pse is not limited to this, and for example, the position where the luminance starts to drop rapidly may be determined as the measured edge position Pse. The etching boundary Pb is also determined by the same method as the measured edge position Pse.

[0058] When the actual edge position Pse of the substrate S is determined in this manner, the above-mentioned problem occurs. This problem will be described with reference to FIG.

[0059] FIG. 11 is a graph showing the relationship between the exposure time in the imaging process and the brightness and edge position of the background image. The solid line in the graph shows the change in the brightness I of the background image IM2 with respect to the exposure time, and the dashed line shows the change in the measured edge position Pse of the substrate S calculated by the above judgment. The following technical features can be read from the graph. That is, as the exposure time increases, the brightness of the background image IM2 increases proportionally, reaches a maximum brightness of 255 at a predetermined exposure time, and is saturated at exposure times longer than that. That is, in the graph, there are a non-saturation section where the brightness of the background image IM2 increases linearly, and a saturation section where the brightness of the background image IM2 is saturated at a maximum brightness of 255. In addition, the measured edge position Pse is approximately constant in the non-saturation section, whereas it increases linearly in the saturation section. Therefore, if the exposure time is increased to the extent that it enters the saturation section in order to improve the SN ratio of the edge inspection image Me, the measured edge position Pse shifts toward the inside of the substrate S according to the exposure time. That is, it becomes difficult to accurately detect the edge position of the substrate S.

[0060] Therefore, in this embodiment, as shown in FIG. 11, the average value Pse(av) of the measured edge positions Pse(1), ..., in the non-saturation section is obtained, and the shift amounts CLm, ..., CLn of the measured edge positions Pse(m), ..., Pse(n) in the saturation section are obtained. Here, the measured edge positions Pse(1), ..., Pse(m), ..., Pse(n) indicate the measured edge positions corresponding to the exposure times ET1, ..., ET(m), ..., ET(n), respectively. Also, the shift amounts CLm, ..., CLn indicate the amount of change from the average value Pse(av) of the measured edge positions Pse(m), ..., Pse(n), respectively. Therefore, the true edge position can be detected by subtracting the shift amount CL from the measured edge position Pse in the saturation section. In this embodiment, the shift amounts CLm, ..., CLn corresponding to the exposure times ETm, ..., ETn, respectively, are used as correction data. These correction data are stored in advance in the storage unit 92 in table format. Then, as will be described next, edge detection is performed using the corrected data.

[0061] Fig. 12 is a flow chart showing substrate processing executed by the substrate processing apparatus shown in Fig. 2. Fig. 13 is a flow chart showing a correction table acquisition process. When the substrate processing apparatus 1 performs bevel etching on the substrate S, the arithmetic processing unit 91 determines whether or not a correction table TBL (Fig. 13) corresponding to the bevel etching process has been obtained (step S1). The correction table is a correction table in which correction data is stored in a table format, as shown in the lower right part of Fig. 13.

[0062] If the determination in step S1 is "YES", the arithmetic processing unit 91 executes a correction table acquisition process (step S2) prior to the bevel etching process on the substrate S. On the other hand, if the determination in step S1 is "NO", the arithmetic processing unit 91 proceeds to step S3 without executing the correction table acquisition process.

[0063] The correction table is acquired by using, as a correction substrate, a substrate S that has been subjected to bevel etching, that is, a substrate having a peripheral portion Ss having the same configuration as the substrate S that is the target of edge position detection (steps S21 to S27). The arithmetic processing unit 91 positions the cup 31 at a lower position by the guard driving unit 33, and prevents the illumination light L1 and the reflected light L2 from being blocked by the cup 31, that is, so-called vignetting. The arithmetic processing unit 91 also positions the head unit 6G at a retreat position P1 (a position indicated by a dashed line in FIG. 3) by the head driving unit 6D. As a result, a transfer space sufficient for the hand of the substrate transfer robot 211 to enter above the spin chuck 21 is formed. Then, when the transfer space formation is confirmed, the arithmetic processing unit 91 issues a loading request for the substrate S to the substrate transfer robot 211, and waits for the substrate S to be carried into the substrate processing apparatus 1 and placed on the upper surface of the spin chuck 21, as shown in FIG. 2. Then, the substrate S is placed on the spin chuck 21 (step S21). Following this, the pump 24 is operated to adsorb and hold the substrate S on the spin chuck 21. Note that in this embodiment, the correction substrate S is stored in a container C and automatically carried in by the substrate transport robot 211, but the correction substrate S may be configured to be placed on the upper surface of the spin chuck 21 by an operator.

[0064] When the loading of the substrate S is completed, the substrate transport robot 211 retreats from the substrate processing apparatus 1. Subsequently, the arithmetic processing unit 91 starts an edge calculation loop. Here, the measured edge positions Pse(1), ..., Pse(m), ..., Pse(n) corresponding to each exposure time ET1, ..., ETm, ..., ETn are acquired. More specifically, each time the variable k is switched in the order of 1, ..., m, ..., n, the arithmetic processing unit 91 controls each unit of the apparatus to capture a correction image (step S22). The correction image is basically the same as the inspection image Me shown in the upper part of FIG. 10. Then, the arithmetic processing unit 91 acquires the measured edge positions based on the correction image (step S23) and temporarily stores them in the storage unit 92. Then, the arithmetic processing unit 91 ends the edge calculation loop.

[0065] Next, the calculation processing unit 91 extracts the measured edge positions included in the non-saturation section from the multiple measured edge positions acquired in the edge calculation loop, and calculates the average value Pse(av) of those (step S24).

[0066] Subsequently, the calculation processing unit 91 starts a correction data calculation loop. Here, in the saturation section, shift amounts CLm, ..., CLn corresponding to the exposure times ETm, ..., ETn are acquired as correction data. More specifically, each time the variable k is switched in the order of m, ..., n, the calculation processing unit 91 sets the difference between the measured edge position Pse(k) and the average value Pse(av) as correction data CLk, that is, the following equation: CLk = measured edge position Pse(k) - average value Pse(av) (Step S25). Then, the calculation processing unit 91 writes and stores the correction data CLk in the correction table TBL in the storage unit 92 in association with the exposure time ETk (Step S26). Then, the calculation processing unit 91 ends the correction data calculation loop.

[0067] Now that the desired correction table TBL has been obtained, the arithmetic processing unit 91 issues an unloading request for the correction substrate S to the substrate transport robot 211. In response to this, the correction substrate S is unloaded from the substrate processing apparatus 1 (step S27).

[0068] 12, the operation will be continued. With the correction table TBL corresponding to the bevel etching process already acquired, the calculation processor 91 issues a loading request for the substrate S to be subjected to the bevel etching process. As a result, the substrate S is loaded onto the spin chuck 21 (step S3) in the same manner as the loading operation of the substrate for correction (step S21).

[0069] Next, the calculation processing unit 91 executes an edge detection process (step S4).

[0070] 14 is a flow chart showing edge detection processing, which is one embodiment of a substrate edge detection method according to the present invention. The calculation processing unit 91 acquires imaging conditions for acquiring an image of the entire peripheral edge of the substrate S (step S41). The imaging conditions include information related to exposure time. In this embodiment, the edge detection processing (step S4) is performed twice in total, once before correcting the eccentricity of the substrate S on the spin chuck 21 and once before inspecting the substrate S that has been subjected to the bevel etching process. Therefore, the imaging conditions may be different before the eccentricity correction and before the inspection.

[0071] Next, the arithmetic processing unit 91 controls each part of the device based on the imaging conditions to obtain an entire peripheral image of the substrate S (step S42). That is, the arithmetic processing unit 91 turns on the light source of the illumination optical system 6E and starts diffuse illumination of the peripheral portion Ss of the substrate S and the adjacent area by the head unit 6G. Subsequently, the arithmetic processing unit 91 issues a rotation command to the rotation drive unit 23 to start rotating the substrate S held by the spin chuck 21. Thereafter, each time the substrate S rotates by a predetermined angle, the arithmetic processing unit 91 extracts an upper surface image Ma, a side surface image Mb, and a lower surface image Mc from the images captured by the observation optical system 6F and joins them together. This process is performed until the substrate S rotates once around the rotation axis AX. As a result, an entire peripheral image of the substrate S including the inspection image Me is obtained.

[0072] The arithmetic processing unit 91 issues a rotation stop command to the rotation drive unit 23 to stop the rotation of the substrate S held by the spin chuck 21, and also turns off the light source to stop the illumination. Following this, the arithmetic processing unit 91 causes the head drive unit 6D to move and position the head unit 6G from the imaging position P2 to the retreat position P1. In parallel with this, the arithmetic processing unit 91 determines the actual edge position based on the inspection image Me included in the entire peripheral image (step S43).

[0073] Thereafter, the arithmetic processing unit 91 judges whether the imaging process in step S42 was performed in a saturated section or a non-saturated section based on information on the exposure time included in the imaging conditions. If the imaging process was performed in a saturated section, the arithmetic processing unit 91 reads out correction data corresponding to the exposure time from the correction table TBL in the storage unit 92, and then corrects the measured edge position with the correction data. This corrected position is determined as the true edge position (step S45). On the other hand, if the imaging process was performed in a non-saturated section, the measured edge position is determined as it is as the true edge position (step S46). In step S46, the average value Pse(av) may be determined as the true edge position.

[0074] Returning to Fig. 12, the description of the operation flowchart will be continued. The edge position information relating to the edge position obtained by the edge detection process executed immediately after loading of the substrate S includes information reflecting the eccentricity of the substrate S with respect to the rotation axis AX. Therefore, in this embodiment, as shown in Fig. 12, the calculation processing unit 91 calculates the amount of eccentricity of the substrate S from the edge position information for one revolution of the substrate S (step S5), and corrects the eccentricity of the substrate S (step S6).

[0075] Next, the processor 91 raises the cup 31 to an upper position by the guard driver 33. As a result, the inner circumferential surface of the cup 31 surrounds the outer periphery of the substrate S held by the spin chuck 21. When preparation for supplying the processing liquid to the substrate S is thus completed, the processor 91 issues a rotation command to the rotary driver 23 to start rotating the spin chuck 21 holding the substrate S. The processor 91 also operates the heater 51 of the peripheral heating mechanism 5. Following this, the processor 91 positions the processing liquid nozzle 44 at the processing start position Ps, and then controls the processing liquid supply unit 45 to supply the processing liquid. As a result, each part of the peripheral portion Ss of the substrate S receives the processing liquid while passing through the processing start position Ps. As a result, a bevel etching process using the processing liquid is performed on the entire peripheral portion Ss of the substrate S (step S7). Then, when the arithmetic processor 91 detects the lapse of the processing time required for the bevel etching process of the substrate S, it issues a supply stop command to the processing liquid supply unit 45 to stop the discharge of the processing liquid. Subsequently, the arithmetic processor 91 issues a rotation stop command to the rotation drive unit 23 to stop the rotation of the spin chuck 21 and also stop the heating by the heater 51.

[0076] When the bevel etching process is completed in this manner, the arithmetic processing unit 91 executes the edge detection process (step S4) shown in FIG. 14 again. As a result, an entire peripheral image after the bevel etching process is obtained, and edge position information for one circumference of the substrate S is obtained (step S4). Based on the entire peripheral image and the edge position information, the arithmetic processing unit 91 inspects the substrate S (step S8). For example, based on the edge position information, the arithmetic processing unit 91 inspects whether the peripheral portion Ss of the substrate S has been bevel etched with a desired WEE width, and displays the inspection result on the input display unit 93 and stores it in the storage unit 92. In addition, the arithmetic processing unit 91 obtains a residue-enhanced image by adding image processing for emphasizing residues to the entire peripheral image. Then, based on the residue-enhanced image, the arithmetic processing unit 91 detects residues remaining in the peripheral portion Ss of the substrate S and adjacent areas, measures the number of residues by size, and reports it as one of the bevel etching results (residue analysis).

[0077] After the inspection, the arithmetic processing unit 91 issues a request to the substrate transport robot 211 to unload the substrate S, and the processed substrate S is unloaded from the substrate processing apparatus 1 (step S9). Note that this series of steps is repeatedly executed.

[0078] As described above, in this embodiment, taking into consideration that the measured edge position measured in the saturation section shifts from the true edge position, correction data corresponding to the shift is stored in advance in the correction table TBL. Then, when the measured edge position is calculated by imaging processing in the saturation section, the measured edge position is corrected with the correction data to detect the true edge position. On the other hand, when the measured edge position is calculated by imaging processing in the non-saturation section, the shift does not occur, so the measured edge position is detected as the true edge position as it is. Therefore, whether the background is bright when imaged or not, the edge position of the substrate S can be found with high accuracy.

[0079] As described above, in the above embodiment, steps S2 and S45 correspond to an example of "step (a)" and "step (b)" of the present invention, respectively. The average value Pse(av) corresponds to an example of the "reference position" of the present invention. The entire peripheral image acquired by the imaging process of step S42 corresponds to an example of the "correction image" of the present invention.

[0080] The present invention is not limited to the above-mentioned embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the embodiment, the peripheral portion Ss of the substrate S is captured in one imaging field of view including images of the peripheral portion Ss viewed from above, the side, and below. However, the edge position calculation process according to the present invention can be performed if there is an image including at least one of the upper surface and the lower surface of the substrate together with its background, and for example, only the upper surface may be captured.

[0081] In the above embodiment, the average value Pse(av) of the measured edge positions Pse(1), ... in the non-saturation section is obtained as the "reference position" of the present invention (step S24), but the method of setting the reference position is not limited to this. For example, one of the measured edge positions in the non-saturation section may be set as the "reference position" of the present invention.

[0082] In the above embodiment, the present invention is applied to the substrate processing apparatus 1 that performs bevel etching on the peripheral portion Ss of the substrate S, but the application of the present invention is not limited thereto, and the present invention can be applied to any technique for capturing images to observe the peripheral portion of a substrate. For example, the present invention can be applied to an inspection technique for inspecting a substrate based on an image captured. The imaging mechanism 6 and the inspection device corresponding to the imaging device according to the present invention can also be applied to a substrate processing apparatus that supplies a coating film remover to the peripheral portion of the substrate S on which a coating film has been formed, thereby removing the coating film from the peripheral portion of the substrate S.

[0083] Furthermore, the substrate processing apparatus 1 in the above embodiment is equipped with a processing section for processing a substrate and an imaging section for imaging the peripheral portion of the substrate. However, even if the device for performing processing on the substrate and the device for imaging the substrate for observation are configured as separate entities, the present invention can be applied as image processing in the latter. [Industrial Applicability]

[0084] The present invention can be applied to any substrate edge detection technology that detects the edge position of a substrate, such as a semiconductor wafer, from an image obtained by capturing an image of the peripheral portion of the substrate. [Explanation of symbols]

[0085] 1...Substrate processing device 6...Imaging mechanism CL, CLm, CLn...shift amount CLk: Shift amount (correction data) ET1,ETk,ETm,ETn...Exposure time IM1: Peripheral image IM2…background image Me…(Edge) Inspection image Pb…etching boundary Pse: Measured edge position RD: Radial direction S...Substrate Ss: (substrate) edge TBL…Correction table

Claims

1. A substrate edge detection method for detecting an edge position of a substrate from an image including a peripheral image corresponding to the peripheral portion and a background image corresponding to the background, the peripheral portion and the background image being obtained by imaging processing for imaging a peripheral portion of the substrate and an adjacent portion having a background with higher luminance than the peripheral portion in a predetermined adjacent direction, the method comprising: (a) acquiring, prior to detecting the edge position, correction data for the edge position with respect to an exposure time in a saturation section in which the luminance of the background image is saturated with respect to a change in the exposure time in the imaging process; (b) determining, as the edge position, a position obtained by correcting an actual edge position detected based on the image obtained by the imaging process within the saturation section in the adjacent direction in accordance with correction data corresponding to the exposure time in the imaging process; A method for detecting an edge of a substrate, comprising:

2. 2. A method for detecting a substrate edge according to claim 1, comprising: The step (a) (a-1) preparing a correction substrate having a peripheral portion having the same configuration as the substrate that is to be subjected to edge position detection; (a-2) acquiring an edge position of the correction substrate as a reference position based on a correction image acquired by the imaging process for the correction substrate in a non-saturated section in which the luminance of the background image is not saturated with respect to a change in the exposure time; (a-3) determining edge positions of the correction substrate based on correction images acquired by the imaging process for the correction substrate within the saturation section and for a plurality of exposure times different from each other, and acquiring differences from the reference positions as the correction data; A method for detecting an edge of a substrate, comprising:

3. 3. A method for detecting a substrate edge according to claim 2, comprising the steps of: The step (a-2) includes a step of determining edge positions of the correction substrate within the non-saturation section and for a plurality of exposure times different from each other, and setting an average value of the plurality of edge positions as the reference position.

4. 4. A substrate edge detection method according to claim 2, further comprising the steps of: (c) a substrate edge detection method comprising the step of determining, as the edge position, an actual edge position detected based on the image obtained by the imaging process within the non-saturation section.

Images