Imaging apparatus, substrate observation apparatus, substrate processing apparatus and imaging method

Abstract

To acquire images suitable for multilaterally observing a peripheral part of a substrate from multiple directions.SOLUTION: An imaging apparatus, a substrate observation apparatus, a substrate processing apparatus and an imaging method according to the present invention guide the light emitted from a peripheral part to an imaging part, periodically execute imaging while creating a first image and a second image obtained by viewing the peripheral part from a first direction and a second direction in an imaging visual field of the imaging part, and perform image processing to each of a first picture including the first image and a second picture including the second image captured by the imaging part. The imaging part cyclically switches between multiple imaging conditions for each imaging, and the multiple imaging conditions include a first condition corresponding to the imaging of the first image and a second condition corresponding to the imaging of the second image. An image processing part acquires the first picture from the pictures captured by the imaging part under the first condition and acquires the second picture from the pictures captured by the imaging part under the second condition.SELECTED DRAWING: Figure 13

Description

[Technical field]

[0001] The present invention relates to a technique for imaging the peripheral portion of a substrate, such as a semiconductor wafer, for the purpose of, for example, inspection. [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, an image of the substrate taken from only one direction is not sufficient. In other words, the cross-sectional shape of the peripheral portion of the substrate varies, and it is impossible to observe the entire substrate from only an image taken from one direction. In addition, the surface state of the substrate differs depending on each region, such as the main surface and side surface, and also depending on the processing state. Therefore, it may be difficult to obtain a good image suitable for observation with a single setting of imaging conditions such as illumination state and exposure time.

[0004] A technology applicable to imaging under such circumstances is, for example, that described in Patent Document 1. This technology relates to an imaging system using a digital camera with, for example, a CCD or CMOS sensor as an imaging element, and realizes a function of storing a plurality of preset imaging conditions in the memory unit of the camera, capturing images while switching between the imaging conditions for each image capture, and outputting the captured image data. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4224504 Summary of the Invention [Problem to be solved by the invention]

[0006] For the purpose of observing the peripheral portion of a substrate including a bevel portion, it is expected that the above-mentioned functions can be used to image the peripheral portion of the substrate under various imaging conditions and to observe it from various angles. However, a specific method for imaging the peripheral portion of a substrate using such functions has not yet been proposed.

[0007] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a technology that can acquire images suitable for multifaceted observation of the peripheral portion of a substrate from multiple directions by switching imaging conditions for each imaging session. [Means for solving the problem]

[0008] One aspect of the invention is an imaging device that images a peripheral portion of a rotating substrate, and includes an imaging section that periodically performs imaging, a light guiding section that guides light emitted from the peripheral portion to the imaging section to create a first image of the peripheral portion viewed from a first direction and a second image of the peripheral portion viewed from a second direction different from the first direction within the imaging field of view of the imaging section, and an image processing section that performs image processing on each of a first image including the first image and a second image including the second image captured by the imaging section.

[0009] Moreover, one aspect of the present invention is an imaging method for imaging a peripheral portion of a rotating substrate, comprising the steps of: guiding light emitted from the peripheral portion to the imaging section to produce a first image of the peripheral portion viewed from a first direction and a second image of the peripheral portion viewed from a second direction different from the first direction within an imaging field of view of the imaging section, while the imaging section periodically performs imaging; and performing image processing on each of a first image including the first image and a second image including the second image captured by the imaging section.

[0010] In these inventions, the imaging unit cyclically switches between a plurality of imaging conditions for each imaging, the plurality of imaging conditions including a first condition corresponding to imaging of the first image and a second condition corresponding to imaging of the second image, and the image processing unit acquires the first image from an image captured by the imaging unit under the first condition, while acquiring the second image from an image captured by the imaging unit under the second condition.

[0011] In the invention configured in this manner, the imaging field of view of the imaging unit includes a plurality of images of the peripheral portion of the substrate viewed from different directions. Therefore, it is possible to use the image captured within the imaging field of view for the purpose of observing the peripheral portion of the substrate from a plurality of directions. However, the imaging conditions suitable for capturing each of the plurality of images are not necessarily the same. Therefore, in the present invention, imaging is performed by cyclically switching among a plurality of imaging conditions for each imaging.

[0012] Specifically, the cyclically switched imaging conditions include a first condition as an imaging condition for capturing a first image, which is an image of the peripheral portion viewed from a first direction, and a second condition as an imaging condition for capturing a second image, which is an image of the peripheral portion viewed from a second direction. Thus, in the periodic imaging performed by the imaging unit, imaging under the first condition and imaging under the second condition are each repeatedly performed.

[0013] The image processing unit obtains a first image including the first image from the images captured under the first condition, obtains a second image including the second image from the images captured under the second condition, and performs image processing on those images. Therefore, good image quality can be obtained by capturing the first image in the first image and the second image in the second image under appropriate capturing conditions.

[0014] In this way, the present invention has a configuration that combines a light guide section that guides light emitted from the substrate to the imaging section so that a plurality of images of the substrate peripheral portion viewed from different directions are included in the imaging field of the imaging section, an imaging section that periodically acquires images while cyclically changing a plurality of imaging conditions, and an image processing section that processes images captured under imaging conditions set corresponding to each image, so that images of the substrate peripheral portion viewed from a plurality of directions can be provided for observation with good image quality.

[0015] In addition, the present invention can be realized as a substrate observation device including a rotation mechanism that holds a substrate and rotates it around a rotation axis perpendicular to the main surface of the substrate, and an imaging mechanism having the same configuration as the imaging device described above, or as a substrate processing device including a rotation mechanism that holds a substrate and rotates it around a rotation axis perpendicular to the main surface of the substrate, a processing unit that performs a predetermined process on the rotating substrate, and an imaging mechanism having the same configuration as the imaging device described above. In the invention configured in this way, the peripheral portion of the substrate can be effectively observed from multiple directions by the above principle. Effect of the Invention

[0016] According to this invention, images of the peripheral portion of the substrate viewed from multiple directions are captured in the imaging field of view, and imaging conditions are switched for each image, and the image captured under the appropriate imaging conditions is selected and processed. This makes it possible to obtain images of good image quality that are suitable for observing the peripheral portion of the substrate from multiple directions in a multifaceted manner. [Brief description of the drawings]

[0017] [Figure 1] 1 is a diagram showing an embodiment of a substrate processing apparatus according to the present invention; [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] 2 is a block diagram showing an electrical configuration of the substrate processing apparatus; 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 illustrating an example of the configuration of an imaging unit in this embodiment. [Figure 11] FIG. 11 is a diagram showing an example of imaging conditions. [Figure 12] 4 is a flowchart showing an imaging operation executed by an imaging section. [Figure 13] FIG. 13 is a conceptual diagram showing a process for creating a full-periphery image from the imaging results. [Figure 14] 1 is a flow chart illustrating image processing that can be applied to create a full perimeter image. [Figure 15] 11 is a diagram showing a preferable relationship between imaging timing and the rotation speed of a substrate. FIG. [Figure 16] 13 is a flowchart showing a modified example of image processing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] 1 is a diagram showing a substrate processing system equipped with an embodiment of a substrate processing apparatus according to the present invention. The substrate processing system 200 includes a substrate processing section 210 that processes a disk-shaped substrate S, such as a semiconductor wafer, and an indexer section 220 that is coupled to the substrate processing section 210. The indexer section 220 is configured to hold a container C for accommodating the substrate S (such as a FOUP (Front Opening Unified Pod) that accommodates multiple substrates S in a sealed state, a SMIF (Standard Insulation Folding Insertion Facility), or a similar container C for accommodating the substrate S). The system is equipped with a container holder 221 capable of holding a plurality of substrates (e.g., pods, OCs (Open Cassettes), etc.), and an indexer robot 222 for accessing the containers C held by the container holder 221 to take out unprocessed substrates S from the container C or store processed substrates S in the container C. Each container C contains a plurality of substrates S in a substantially horizontal position.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] The imaging mechanism 6 has a base 6A, a pivot 6B, an arm 6C, a head driver 6D, a light source 6E, an imaging unit 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 the tip of the arm 6C. 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.

[0034] As shown in FIG. 3, the light source 6E and the imaging unit 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 light source 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 peripheral portion Ss of the substrate S is illuminated by the diffused light thus generated. 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 imaging unit 6F. As a result, the imaging section 6F acquires an image of the peripheral portion Ss of the substrate S, and sends the image data to the control unit 9.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] As described above, the head unit 6G has both a diffusion illumination function of receiving illumination light L1 from the light source 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 imaging unit 6F. The configuration and operation of the head unit 6G will be described below with reference to Figs. 6 to 9.

[0039] 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.

[0040] The diffuse lighting section 61 is made of white 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.

[0041] In the diffuse illumination section 61, a diffuse surface 610 is provided along the cutout portion 611. The diffuse 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 the diffuse surface 610 that diffusely reflects the illumination light and causes it to be incident on the peripheral portion Ss of the substrate S.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] As will be described in detail later, the imaging unit 6F captures images in an imaging field of view that is set to include 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 imaging unit 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.

[0046] 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."

[0047] 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.

[0048] 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 imaging unit 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.

[0049] 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.

[0050] 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.

[0051] 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 imaging unit 6F arranged on the optical path. This realizes "side imaging" for imaging the peripheral portion Ss of the substrate S as viewed from the side.

[0052] The imaging unit 6F has an observation lens system 6Fa composed of an object-side telecentric lens, and a CMOS camera 6Fb. Therefore, only light rays L2 (L2a, L2b, L2c) parallel to the optical axis of the observation lens system 6Fa among the above-mentioned reflected light are incident on the sensor surface of the CMOS camera 6Fb, 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 imaging unit 6F images 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 shown in FIG. Then, the imaging unit 6F transmits image data indicating the image to the control unit 9.

[0053] 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 imaging unit 6F. In this way, the imaging field of view FV of the imaging unit 6F is set to include the mirror members 62a to 62c of the head unit 6G.

[0054] FIG. 9(b) is a schematic diagram showing images of the substrate S reflected on the mirror members 62a to 62c in the imaging field of view FV. As shown in FIG. 9(b), the first mirror member 62a reflects images of the A-side Sa and B-side Sb of the peripheral portion Ss of the substrate S. The second mirror member 62b reflects images of the B-side Sb, C-side Sc, and D-side Sd of the peripheral portion Ss of the substrate S. The third mirror member 62c reflects images of the D-side Sd and E-side Se of the peripheral portion Ss of the substrate S. The imaging unit 6F simultaneously captures these images collectively to obtain one image. The surfaces Sa to Se included in one image are captured simultaneously, and are in a relationship in which the circumferential positions of the substrate S are substantially the same as one another.

[0055] 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 light source 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, neither the amount of illumination light nor the amount of received light can be said to be 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.

[0056] 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.

[0057] 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 (etching width), etc.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] As described above, in this embodiment, the imaging unit 6F images the peripheral portion Ss of the substrate S with the peripheral portion Ss inserted into the notch 611 of the head unit 6G. The substrate S rotates at a constant speed, and the imaging unit 6F periodically captures images while the substrate S makes one rotation. By combining the images captured at each time, it is possible to obtain images of the peripheral portion Ss corresponding to the entire circumference of the substrate S, that is, an entire peripheral image.

[0062] The captured image Im includes an upper image area Ma corresponding to the image of the peripheral portion Ss viewed from above, a side image area Mb corresponding to the image viewed from the side, and a lower image area Mc corresponding to the image viewed from below. Therefore, the entire peripheral image includes information representing the state of the substrate S when the peripheral portion Ss is viewed from above, the side, and below, for the entire circumference of the substrate S. By analyzing this entire peripheral image using an appropriate image processing technique, it is possible to perform a visual inspection of the peripheral portion Ss.

[0063] In the above-mentioned imaging of the image Im and the image processing based thereon, the observation is performed using the top image area Ma, the side image area Mb, and the bottom image area Mc, which are simultaneously acquired in one imaging. However, in reality, the following two problems may occur depending on the situation.

[0064] The first problem is the image quality of each of the image regions. The surface condition of the peripheral portion Ss of the substrate S is not uniform, and each surface may not be imaged with good image quality under a single imaging condition. In particular, the surface conditions may differ significantly between the upper surface, side surface, and lower surface of the substrate S because the type and thickness of the coating formed thereon, the processing state, etc. differ from one another. Due to this, the imaging conditions suitable for imaging each surface are not uniform. For example, if a coating with low reflectance is formed on the upper surface of the substrate S, adjusting the exposure to image it well may result in overexposure on the side surface and lower surface, causing whiteout in the image.

[0065] Conversely, if the exposure is adjusted to match the surface with high reflectivity, the image of the surface with low reflectivity may not be bright enough, may be susceptible to image noise, and may not provide sufficient contrast for observation. In this way, it may be difficult to capture each surface with good image quality under a single imaging condition. The exposure can be adjusted, for example, by increasing or decreasing the amount of illumination light or the exposure time.

[0066] The second problem is data capacity. The image Im includes areas other than the upper image area Ma, the side image area Mb, and the lower image area Mc that are the objects of observation. Such unused areas can be removed by the arithmetic processing unit 91 performing image processing. However, the image signal sent from the imaging unit 6F includes data of such unused areas, which may put a strain on the storage capacity of the storage unit 92 and the capacity of the communication line between the devices.

[0067] For example, in order to obtain an image of the entire periphery, it is necessary to take images of the substrate S many times in a short time while rotating the substrate S, and a large amount of image data is generated temporarily. In particular, in a case where a plurality of processing units 1 is provided as in the substrate processing system 200 (FIG. 1) of this embodiment, and these processing units 1 are controlled by a single control unit 9 or a control unit 9 whose number is less than the number of processing units 1, the image data sent by the imaging section 6F of each processing unit 1 at its own timing may occupy a large amount of communication lines and storage resources. There is a concern that this may cause a disruption to the operation of the entire system.

[0068] In this embodiment, the imaging unit 6F, which periodically captures images, responds to the first problem by capturing images while cyclically switching between a plurality of preset imaging conditions for each capture. For example, the technology described in Patent Document 1 registers a plurality of imaging conditions in advance in a storage unit of an imaging device, and cyclically calls and applies the imaging conditions for each capture. This function is called a sequential shutter function or a sequencer function.

[0069] As a measure to address the second problem, only the area to be observed out of the imaging field of view FV (FIG. 8(a)) of the imaging unit 6F is converted into image data and sent from the imaging unit 6F. By not sending image data of unused areas, it is possible to avoid putting strain on communication lines and storage resources. The function of setting a part of the imaging field of view as a Region of Interest (ROI) and converting and outputting only the image within the Region of Interest into image data is called the ROI function, ROI mode, etc., but hereinafter it will be called the "ROI setting function."

[0070] Using this function not only makes it possible to reduce the amount of data, but also makes it possible, for example, to set different image quality levels for necessary and unnecessary areas, or to increase the frame rate by eliminating the scanning of unnecessary areas.

[0071] Imaging devices having both the above-mentioned sequential shutter function and ROI setting function are also commercially available as industrial cameras, and in this embodiment, an imaging device having such functions can be used as the imaging section 6F.

[0072] FIG. 10 is a diagram showing an example of the configuration of the imaging unit in this embodiment. The imaging unit 6F is a commercially available camera having the above-mentioned sequential shutter function and ROI setting function as an imaging device, and mainly includes an imaging element 6Fa, an imaging optical system 6Fb, a control unit 6Fc, a storage unit 6Fd, and an interface 6Fe. The imaging element 6Fa is, for example, a CCD sensor or a CMOS sensor, and outputs an image signal according to the amount of light incident on each position of its light receiving surface. The imaging optical system 6Fb focuses the incident light on the light receiving surface to form an optical image within the imaging field of view FV.

[0073] The control unit 6Fc controls each part of the imaging unit 6F, and the storage unit 6Fd stores various information. This information includes image data generated by imaging, information about frame rate and sensitivity, information about the settings of the imaging conditions and the settings of the region of interest (ROI), and the like. The imaging operation of this embodiment described below is realized by the cooperation of these parts. The interface 6Fe is connected to the control unit 9 via the communication path C, receives control commands related to imaging from the control unit 9, and transmits image data acquired by imaging to the control unit 9.

[0074] As described above, the sequential shutter function of the imaging unit 6F, which captures images while switching between multiple preset imaging conditions, and the ROI setting function, which digitizes and outputs only a portion of the region of interest within the imaging field of view, have already been put to practical use, so detailed explanations will be omitted here.

[0075] The imaging unit 6F of this embodiment images the top surface image area Ma, the side surface image area Mb, and the bottom surface image area Mc included in the imaging field of view FV under optimal imaging conditions, while not converting the other areas into data, thereby solving both of the above-mentioned two problems. Specifically, three types of imaging conditions optimized for the top surface image area Ma, the side surface image area Mb, and the bottom surface image area Mc are determined in advance, and the imaging unit 6F periodically captures images while switching between these three types of imaging conditions for each capture.

[0076] Here, three types of imaging conditions are used: imaging conditions suitable for imaging the top image area Ma (hereinafter referred to as "imaging condition (1)"), imaging conditions suitable for imaging the side image area Mb (hereinafter referred to as "imaging condition (2)"), and imaging conditions suitable for imaging the bottom image area Mc (hereinafter referred to as "imaging condition (3)").

[0077] In this embodiment, the length of the exposure time and the range of the region of interest are set as variable parameters that determine the imaging conditions, but the parameters used are not limited to these. For example, various factors that affect image quality, such as the frame rate, the resolution and sensitivity of the image sensor 6Fa, the aperture value of the imaging optical system 6Fb, and the amount of illumination light, can be used as variable parameters. In addition, the specific numerical values ​​and the like listed below are merely setting examples for explanation, and the setting values ​​are not limited to these examples and can be changed appropriately depending on the purpose.

[0078] FIG. 11 is a diagram showing an example of imaging conditions. Imaging condition (1) is an imaging condition for optimizing image quality in imaging the top surface of the substrate S viewed from above downward. By imaging under this imaging condition (1), an image having image quality suitable for observing the A surface Sa and B surface Sb of the substrate peripheral portion Ss that are visible from above can be obtained. For this purpose, the exposure time is set to 100 μs. The region of interest (ROI) in the imaging field of view FV is set to an area Ra that reliably and sufficiently includes the top surface image area Ma, while excluding areas not required for observation as much as possible.

[0079] Moreover, the imaging condition (2) is an imaging condition for optimizing the image quality in imaging the side surface of the substrate S as viewed from the side. By imaging under this imaging condition (2), an image having an image quality suitable for observing the B surface Sb, the C surface Sc, and the D surface Sd of the substrate peripheral portion Ss that are visible from the side can be obtained. For this purpose, the exposure time is set to 50 μs. Furthermore, the region of interest (ROI) in the imaging field of view FV is set to an area Rb that reliably includes the side image area Mb with a sufficient area, and excludes areas not required for observation as much as possible.

[0080] Moreover, the imaging condition (3) is an imaging condition for optimizing the image quality in imaging the underside of the substrate S as viewed from below. By imaging under this imaging condition (3), an image having image quality suitable for observing the D surface Sd and the E surface Se of the substrate peripheral portion Ss that are visible from below can be obtained. For this purpose, the exposure time is set to 150 μs. The region of interest (ROI) in the imaging field of view FV is set to an area Rc that reliably and sufficiently includes the underside image area Mc, while excluding areas not required for observation as much as possible.

[0081] 12 is a flowchart showing the imaging operation performed by the imaging section. This operation is performed by operating the imaging mechanism 6, particularly the imaging section 6F, in response to a control command from the control unit 9. The operation of the imaging section 6F can be realized by the control section 6Fc executing a control program stored in advance in the storage section 6Fd, but it may also be possible for the arithmetic processing section 91 of the control unit 9 to directly control the imaging section 6F based on the control program stored in the storage section 92.

[0082] First, the frame rate and imaging conditions for periodic imaging are set (step S101). In this embodiment, when the substrate peripheral portion Ss is imaged periodically, the frame rate is maintained at the value initially set. That is, the frame rate is not changed for each imaging. Furthermore, as imaging conditions, N types (N is a natural number of 2 or more) of imaging conditions (1) to (N) can be registered, but in the above example, N=3, and the contents of each imaging condition are as described above. Information on these settings is provided from the control unit 9 to the interface 6Fe of the imaging section 6F via the communication path C, and is stored in the storage section 6Fd. In this way, the imaging conditions are registered in the imaging section 6F. Thereafter, the control section 6Fc reads out this information from the storage section 6Fd and controls the imaging element 6Fa and the like as follows to perform imaging.

[0083] First, an internal parameter i is set to an initial value of 1 (step S102). Then, from among the imaging conditions registered in advance, an imaging condition (i) specified by the internal parameter i is selected (step S103), and imaging (exposure) is performed using the imaging condition (step S104).

[0084] The control unit 6Fc digitizes the image of the region of interest in the exposed imaging field of view FV, and outputs the generated image data to the control unit 9 via the interface 6Fe (step S105). The image data received by the control unit 9 is stored in the storage unit 92. In the first processing, the internal parameter i is 1, so imaging condition (1) is applied to the imaging, and only image data related to the region of interest Ra set corresponding to the top surface image area Ma is output. Therefore, the top surface image area Ma can be imaged with good image quality, and the amount of data output can be small.

[0085] After the first imaging is performed in this manner, the internal parameter i is incremented by one (step S106), and steps S103 to S106 are repeated until the conditional expression "i>N" is satisfied (step S107). As a result, imaging condition (2) is applied in the second imaging, and image data of the region of interest Rb set corresponding to the side image region Mb is output. Similarly, imaging condition (3) is applied in the third imaging, and image data of the region of interest Rc set corresponding to the bottom image region Mc is output. Furthermore, in the fourth and subsequent imaging, imaging conditions (1) to (3) are applied cyclically, and image data of the regions of interest Ra, Rb, Rc, Ra, ... are acquired in order.

[0086] The above imaging operation is repeated while rotating the substrate S at a predetermined speed. When images are acquired for at least one revolution of the substrate S, it can be determined that imaging is complete (step S108). In this manner, image data of the region of interest Ra imaged under imaging condition (1), image data of the region of interest Rb imaged under imaging condition (2), and image data of the region of interest Rc imaged under imaging condition (3) are acquired for each revolution of the substrate S. Using these image data, it is possible to create full peripheral images of the substrate peripheral portion Ss as viewed from above, the side, and below.

[0087] For the sake of later explanation, the processing loop of steps S102 to S108 is defined as an "imaging loop", and the first imaging loop executed is referred to as "imaging loop 1" or simply as "loop 1". Furthermore, the second and subsequent imaging loops will be referred to as "imaging loop 2 (or loop 2)", "imaging loop 3 (or loop 3)", ...

[0088] Fig. 13 is a conceptual diagram showing the process of creating an all-periphery image from the imaging results. It is considered that, through the imaging operation described above, an image Ra1 is acquired by imaging the region of interest Ra by applying imaging condition (1) at time T1. Similarly, an image Rb2 is acquired by imaging the region of interest Rb by applying imaging condition (2) at time T2, and an image Rc3 is acquired by imaging the region of interest Rc by applying imaging condition (3) at time T3. At time T4, the region of interest Ra is imaged by applying imaging condition (1) again, and an image Ra4 is acquired. The same can be considered for times T5 and after.

[0089] An entire peripheral image of the substrate peripheral portion Ss viewed from above can be created by arranging and synthesizing images Ra1, Ra4, Ra7, ... captured under imaging condition (1) with the top surface image region Ma as the region of interest Ra in a direction corresponding to the circumferential direction of the substrate S. An entire peripheral image of the substrate peripheral portion Ss viewed from the side can be created by arranging and synthesizing images Rb2, Rb5, Rb8, ... captured under imaging condition (2) with the side surface image region Mb as the region of interest Rb in a direction corresponding to the circumferential direction of the substrate S. An entire peripheral image of the substrate peripheral portion Ss viewed from below can be created by arranging and synthesizing images Rc3, Rc6, Rc9, ... captured under imaging condition (3) with the bottom surface image region Mc as the region of interest Rc in a direction corresponding to the circumferential direction of the substrate S.

[0090] 14 is a flowchart showing image processing that can be applied to the creation of a full-periphery image. This processing is realized by the arithmetic processing section 91 of the control unit 9 executing a control program pre-stored in the storage section 92, and performing a predetermined process on the image data acquired by the imaging section 6F and stored in the storage section 92.

[0091] First, an internal parameter j is set to an initial value of 1 (step S201). Then, from the images whose data is stored in the storage unit 92, images captured under the imaging condition (j) are extracted (step S202), and a synthesis process is performed to stitch together images of one circumference of the substrate (step S203) to create an entire peripheral image. The image data of the created entire peripheral image is stored in the storage unit 92. While the internal parameter j is incremented by one (step S204), this process is repeated N times (step S205) to create all necessary entire peripheral images.

[0092] For example, by combining images Ra1, Ra4, Ra7, ... captured under imaging condition (1), an image of the entire peripheral portion Ss of the substrate as viewed from above can be created. The same can be considered for images captured under imaging condition (2) and imaging condition (3).

[0093] Next, other issues to be considered when imaging the peripheral portion Ss of the substrate S and creating an entire peripheral image as described above will be described. In the above process, the three regions of interest Ra, Rb, and Rc are imaged in sequence, so one image is obtained for each region of interest every three times. In order to create an entire peripheral image, it is necessary to obtain images of the peripheral portion Ss for one revolution of the substrate S without missing any image information, and to make this possible, the relationship between the imaging timing required and the rotation speed of the substrate will be considered.

[0094] FIG. 15 is a diagram showing a schematic diagram of a preferable relationship between the imaging timing and the rotation speed of the substrate. As shown in FIG. 15, the imaging timing is considered with the horizontal axis being the rotation phase angle θ of the substrate S from an appropriately determined reference position and the vertical axis being the time T. When imaging is performed periodically while changing the internal parameter i from 1, 2, 3, ..., images Ra1, Rb2, Rc3, ... are obtained in sequence each time the imaging times T1, T2, T3, ... arrive. During this time, since the substrate S is rotating, the rotation phase angle θ also changes in sequence. Note that, for convenience of explanation, the images of the regions of interest Ra, Rb, Rc are all shown as being the same size, but as shown in FIG. 11, the sizes of these images are not necessarily the same.

[0095] The entire peripheral image of the region of interest Ra is created by stitching together images Ra1, Ra4, Ra7, ... captured when i=1, that is, under imaging condition (1). In this case, in order to prevent loss of information about the substrate S, it is necessary that the imaging ranges of these images Ra1, Ra4, Ra7 overlap on the substrate S.

[0096] Where: The width of the region of interest imaged at one time (imaging width) is represented by W [mm]. The frame rate of the image is represented by R [fps = frames per second]. The diameter of the substrate S is denoted by D [mm]. The rotation speed of the substrate S is represented by n [rpm = revolutions per minute]. =n / 60[rps=revolutions per second] Let it be expressed as follows.

[0097] Since the number of images taken while the substrate S rotates once can be expressed as (60R / n), when N types of imaging conditions are cyclically switched, the number of images taken per rotation under the same imaging conditions can be expressed as 60R / (Nn). For example, when N=3, the number of images taken per rotation under the same imaging conditions can be expressed as 20R / n.

[0098] On the other hand, since the perimeter of the substrate S can be expressed as πD using the circular constant π, the condition for adjacent images to overlap under the same imaging conditions is as follows: W>πD / {60R / (Nn)}=πDNn / (60R) … (Equation 1) For example, when N=3, (Equation 1) can be expressed as follows: W>πDn / (20R) … (Equation 2) If each value is set to satisfy this condition, multiple images having overlapping portions can be obtained. Techniques for stitching together images having overlapping portions and different imaging ranges are well known, and such well-known techniques can be used to form an entire peripheral image without any missing parts.

[0099] In addition, the diameter D of the substrate S and the number of rotations n are determined by the specifications of the substrate processing, and the number of imaging conditions N is set according to the purpose of the observation, so it is considered that these cannot be selected arbitrarily. Therefore, in reality, the above conditions can be satisfied by selecting a combination of the imaging width W and the frame rate R.

[0100] As an example, when the diameter D of the substrate S is 300 mm, the rotation speed n is 20 rpm, and the number of imaging conditions N is 3, (Equation 1) is changed to the following equation: W>300π / R … (Formula 3) In this case, the above conditions are met by setting W=3[mm] and R=360[fps]. In addition, the imaging period (1 / R) is about 2.8 ms, so the exposure time of 50 to 150 μs specified in each imaging condition above can be sufficiently secured.

[0101] Incidentally, when three regions of interest are imaged simultaneously under a single imaging condition, that is, when N=1, if the imaging width W is the same (3 mm), the frame rate R can be 120 fps. In other words, in order to implement this embodiment, a higher frame rate is required compared to imaging under a single condition. Naturally, there is an upper limit to the frame rate that can be achieved by a general imaging device, but if the imaging device has an ROI setting function, it is possible to achieve a higher frame rate than when the entire imaging field of view FV is digitized by converting only the region of interest (ROI) therein, rather than the entire imaging field of view FV.

[0102] For example, if the imaging element 6Fa uses a CCD sensor or a CMOS sensor, a higher frame rate than usual can be realized because the photoelectrically converted signal only needs to be read out for the region of interest. Therefore, if the imaging device is capable of imaging the entire imaging field of view FV at a frame rate of 120 fps, imaging at a frame rate of 360 fps can be realized by making the area of ​​the region of interest for each image capture smaller than (1 / 3) of the imaging field of view FV.

[0103] 15, in the imaging operation of this embodiment, the regions of interest Ra, Rb, and Rc are not imaged simultaneously, so that a position shift of Δθ [rad] occurs between images captured in the same imaging loop, in terms of the rotation angle of the substrate S. Δθ is expressed by the following formula: Δθ=2πn / (60R)=πn / (30R) … (Formula 4) When observing by comparing the positions of all-periphery images created under different imaging conditions, this positional deviation must be corrected.

[0104] As described above, in this embodiment, the head unit 6G having three mirror members 62a to 62c is configured to cause images of the peripheral portion Ss of the substrate S viewed from different directions, more specifically, a top image area Ma corresponding to the image viewed from above, a side image area Mb corresponding to the image viewed from the side, and a bottom image area Mc corresponding to the image viewed from below, all to appear in the imaging field of view FV of the imaging unit 6F.

[0105] The imaging unit 6F periodically captures images while cyclically switching among a plurality of imaging conditions that have been set and registered in advance, and outputs only image data of the region of interest that has been set under the imaging conditions. Meanwhile, the arithmetic processing unit 91 that has received the image data extracts images captured under the same imaging conditions from among the plurality of images thus acquired, and performs image processing.

[0106] In this way, by combining a configuration for guiding images of the substrate S viewed from multiple directions into the imaging field of view FV, a configuration for capturing images while cyclically switching between multiple imaging conditions, a configuration for outputting only image data of the region of interest from the imaging field of view FV, and a configuration for extracting images captured under the same imaging conditions and performing image processing, the present embodiment can achieve the following effects.

[0107] First, images of the substrate S viewed from different directions can be captured under imaging conditions suited to each direction, so that images of good image quality can be acquired for each direction. As a second effect associated with this, images of each of a plurality of regions of interest can be acquired under optimized imaging conditions while the substrate S makes one revolution.

[0108] Thirdly, by digitizing only the necessary area of ​​the imaging field of view FV, it is possible to speed up imaging and achieve a higher frame rate. Fourthly, by outputting only the image data of the necessary area, it is possible to reduce the data volume and ease the strain on data communication paths and storage resources. This effect is particularly noticeable when processing after acquiring images of the entire circumference of the substrate S or when processing image data output from multiple processing units 1.

[0109] In the above embodiment, only a portion of the imaging field of view FV is digitized using the ROI setting function of the imaging device. However, if there is sufficient frame rate and data capacity, it is also possible to extract the regions of interest Ra, Rb, Rc from an image capturing the entire imaging field of view FV after the fact, without using the ROI setting function.

[0110] In this case, the imaging operation may be modified so that the entire imaging field of view FV is always treated as the region of interest in the process shown in Fig. 12. As a result, imaging is performed under conditions where the region of interest is constant but other imaging conditions, such as exposure time, change for each imaging. This results in multiple images being acquired with different exposure times for the entire imaging field of view FV. Meanwhile, image processing in the calculation processing unit 91 can be performed as follows.

[0111] Fig. 16 is a flow chart showing a modified example of image processing. The process is the same as that shown in Fig. 14 in that an image captured under imaging condition (j) is acquired using internal parameter j (steps S301, S302). The image at this time includes a top image region Ma, a side image region Mb, and a bottom image region Mc, but only one of them is captured with good image quality, and the image quality of the other image regions is not necessarily guaranteed. Therefore, a region where good image quality can be obtained under imaging condition (j) is cut out as a region of interest R(j) (step S303).

[0112] The image content of the region of interest R(j) cut out in this way is substantially the same as the image content when only the region of interest is digitized at the imaging stage. Therefore, by synthesizing the regions of interest cut out from images captured under the same conditions (step S304), it is possible to create a full peripheral image. The process is also repeated while incrementing the parameter j (steps S305 and S306), which is similar to the process in FIG. 14.

[0113] As described above, in the above embodiment, the processing unit 1 functions as the "imaging device," "substrate observation device," and "substrate processing device" of the present invention. In addition, the rotation mechanism 2, the processing mechanism 4, and the arithmetic processing unit 91 function as the "rotation mechanism," "processing unit," and "image processing unit" of the present invention, respectively. In addition, the imaging unit 6F and the head unit 6G of the imaging mechanism 6 function as the "imaging unit" and "light guide unit" of the present invention, respectively, and the imaging mechanism 6 and the arithmetic processing unit 91 cooperate to function as the "imaging device" and "imaging mechanism" of the present invention. In addition, the memory unit 6Fd provided in the imaging unit 6F functions as the "memory unit" of the present invention.

[0114] In this embodiment, the images of the peripheral portion Ss of the substrate S viewed from above, the side, and below are the objects of observation, and one of these directions can be interpreted as the "first direction" of the present invention, and one of the other directions can be interpreted as the "second direction" of the present invention. Similarly, one of these images can be interpreted as the "first image" of the present invention, and one of the other images can be interpreted as the "second image" of the present invention, and images that individually represent these correspond to the "first image" and "second image" of the present invention. Furthermore, one of the multiple imaging conditions (1) to (N) can be interpreted as the "first condition" of the present invention, and the other can be interpreted as the "second condition" of the present invention.

[0115] 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 region of interest including the images of the peripheral portion Ss of the substrate S viewed from three directions, namely, above, side, and below, is set as the observation target, and three types of imaging conditions adapted to the region of interest are set. However, the number of regions of interest is not limited to this, and can be set appropriately according to the purpose. In addition, the number of regions of interest and the number of imaging conditions set may not be the same. For example, if the same imaging conditions can be applied between multiple regions of interest, it is also possible to obtain images of the multiple regions of interest in one imaging.

[0116] Conversely, one region of interest may be imaged under a plurality of different imaging conditions. For example, it is possible to obtain images of different brightness for the same region by imaging one region of interest under a plurality of imaging conditions with different exposure times. For example, even if the surface condition of the substrate S varies greatly and the brightness varies depending on the position, it is possible to perform efficient observation by obtaining images imaged with different exposure times.

[0117] To give a specific example in accordance with the above embodiment, for example, if two types of imaging conditions with different exposure times are set for imaging the top image area Ma, and one type of imaging condition is set for imaging the side image area Mb and the bottom image area Mc, imaging will be performed while cyclically switching between a total of four types of imaging conditions. Then, for the top image area Ma, it becomes possible to create two full-periphery images that are imaged under different imaging conditions and have different brightness, etc.

[0118] Also, for example, by imaging the same region of interest multiple times under the same imaging conditions, it is possible to improve the substantial resolution and reduce image noise. Note that the "same region of interest" here refers to the region set at the time of imaging, and does not necessarily mean that the range actually imaged is the same. In other words, since the rotating substrate S is imaged multiple times at different times, the range of the region on the substrate S that is imaged differs slightly. However, as described above, the amount of this positional deviation can be grasped based on the number of rotations of the substrate S and the imaging period, and therefore correction can be made as necessary.

[0119] In this way, it is arbitrary to determine how many regions of interest are set within the imaging field of view FV and how many imaging conditions are set for each of them, and it is also arbitrary to determine which factors are changed as imaging conditions.

[0120] In the above embodiment, the observation lens system of the imaging unit 6F is configured with an object-side telecentric lens, but the configuration of the observation lens system of the imaging unit 6F is not limited to this. The observation lens system of the imaging unit 6F may be configured with other lenses.

[0121] Furthermore, there is no limitation on the configuration of the diffusion surface 610 (61a to 61c) of the diffusion illumination unit 61. For example, when at least a part of the diffusion illumination unit 61 or the holding unit 63 is made of a metal material, the diffusion surfaces 61a to 61c may be made by subjecting the surface of the metal material to shot blasting.

[0122] The mirror members 62a to 62c are not limited to Si (silicon). That is, other materials may be used as long as they have chemical resistance to the processing liquid and heat resistance to the processing temperature. The mirror members 62a to 62c may be configured, for example, by depositing a metal material on the surface of a material having chemical resistance and heat resistance. Furthermore, when the mirror members 62a to 62c are used in an environment in which chemical resistance and heat resistance are not required, the constituent material is not limited. The mirror members 62a to 62c may be configured of a material that does not have chemical resistance and heat resistance. The mirror members 62a to 62c may be configured, for example, by depositing a metal material on the surface of a material that does not have chemical resistance and heat resistance.

[0123] 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 arithmetic processing unit 91, which correspond 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, to remove the coating film from the peripheral portion of the substrate S.

[0124] In addition, the processing unit 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 an apparatus for performing processing on a substrate and an apparatus for imaging the substrate for observation are configured separately, the present invention can be applied as image processing in the latter.

[0125] As described above by way of example of specific embodiments, in the imaging device according to the present invention, the substrate observation device and substrate processing device having an imaging mechanism of the same configuration as the imaging device, and the imaging method using the imaging device, the imaging unit may output image data corresponding to a region of interest that is a part of the imaging field of view, and the region of interest may be changeable. In this case, the imaging conditions may include a setting related to the range of the region of interest in the imaging field of view.

[0126] With this configuration, it is possible to reduce the amount of data corresponding to an image, thereby reducing the burden on communication paths and storage resources for transmitting the data. Also, by shortening the time required to digitize an image, it is possible to shorten the image capture cycle and capture images at a higher frame rate.

[0127] For example, the imaging unit may have a storage unit that stores a plurality of imaging conditions, and may be configured to perform imaging by applying the imaging conditions read from the storage unit. With such a configuration, the imaging unit can periodically perform imaging while autonomously changing the imaging conditions, and it is not necessary to externally specify the imaging conditions each time imaging is performed.

[0128] Also, for example, the imaging unit may be configured to perform imaging a plurality of times for each of a plurality of imaging conditions while the substrate rotates once. With such a configuration, the peripheral portion of the substrate can be imaged at a plurality of positions in the circumferential direction. Also, by performing such imaging, the image processing unit can create a composite image by combining a plurality of first images captured at different times.

[0129] In this case, it is preferable that the imaging unit captures the first images captured closest to each other so that the two first images partially overlap each other. With this configuration, it is possible to create a composite image that covers the entire circumference of the substrate without any loss.

[0130] In addition, the multiple imaging conditions can be, for example, different exposure times. The optical state of the surface of a substrate varies depending on the processing state, etc., and it may be difficult to obtain brightness suitable for observation and good image quality in all directions when imaging with a single exposure time. This problem can be solved by imaging with different exposure times.

[0131] For example, the first image may be an image of the main surface of the substrate, and the second image may be an image of the side surface of the substrate. Since the present invention can obtain images of the substrate from multiple directions with good image quality, it is possible to efficiently observe the main surface and side surface of the substrate, which have significantly different surface conditions. For example, in order to inspect the processing state of the bevel portion of the substrate, it is necessary to observe both the main surface side and the side surface side, and the present invention is suitable for such applications. [Industrial Applicability]

[0132] The present invention can be applied to applications in which the peripheral portion of a substrate, particularly a circular substrate such as a semiconductor wafer, is imaged and observed, and is particularly suitable for applications in which the circumferential direction of the substrate needs to be observed from multiple directions. [Explanation of symbols]

[0133] 1 Processing unit (imaging device, substrate observation device, substrate processing device) 2 Rotation mechanism 4 Processing mechanism (processing section) 6 Imaging mechanism 6E light source 6F Imaging section (imaging section) 6Fd storage section 6G Head section (light guide section) 91 Calculation processing section (image processing section) S-substrate Ss Peripheral Department

Claims

1. An imaging device for imaging a peripheral portion of a rotating substrate, comprising: an imaging unit that periodically performs imaging; a light guide section that guides light emitted from the peripheral portion to the imaging section to create a first image of the peripheral portion viewed from a first direction and a second image of the peripheral portion viewed from a second direction different from the first direction within an imaging field of view of the imaging section; an image processing unit that performs image processing on each of a first image including the first image and a second image including the second image captured by the imaging unit; Equipped with the imaging unit cyclically switches among a plurality of imaging conditions for each imaging, the plurality of imaging conditions including a first condition corresponding to imaging of the first image and a second condition corresponding to imaging of the second image; The image processing unit obtains the first image from an image captured by the imaging unit under the first condition, and obtains the second image from an image captured by the imaging unit under the second condition.

2. The imaging device according to claim 1 , wherein the imaging section outputs image data corresponding to a region of interest that is a part of the imaging field of view, and the region of interest is changeable.

3. The imaging device according to claim 2 , wherein the imaging conditions include a setting related to a range of the region of interest within the imaging field of view.

4. The imaging device according to claim 1 , wherein the imaging section includes a storage section that stores the plurality of imaging conditions, and performs the imaging by applying the imaging conditions read from the storage section.

5. The imaging device according to claim 1 , wherein the imaging section performs the imaging a plurality of times for each of the plurality of imaging conditions while the substrate makes one rotation.

6. The imaging device according to claim 5 , wherein the image processing unit creates a composite image by combining a plurality of the first images captured at different times.

7. The imaging device according to claim 6 , wherein the imaging section captures images such that two of the first images captured closest in time partially overlap each other.

8. The imaging device according to claim 1 , wherein the first condition and the second condition have different exposure times.

9. The imaging device of claim 1 , wherein the first image is an image of a main surface of the substrate, and the second image is an image of a side surface of the substrate.

10. a rotation mechanism that holds a substrate and rotates the substrate about a rotation axis perpendicular to a main surface of the substrate; An imaging mechanism having the same configuration as the imaging device according to any one of claims 1 to 9; A substrate observation device comprising:

11. a rotation mechanism that holds a substrate and rotates the substrate about a rotation axis perpendicular to a main surface of the substrate; A processing unit that performs a predetermined process on the rotating substrate; An imaging mechanism having the same configuration as the imaging device according to any one of claims 1 to 9; The substrate processing apparatus includes:

12. 1. A method for imaging a peripheral portion of a rotating substrate, comprising: a step of guiding light emitted from the peripheral portion to the imaging section, and forming a first image of the peripheral portion viewed from a first direction and a second image of the peripheral portion viewed from a second direction different from the first direction within an imaging field of view of the imaging section, while the imaging section periodically captures images; performing image processing on each of a first image including the first image and a second image including the second image captured by the imaging unit; Equipped with the imaging unit cyclically switches among a plurality of imaging conditions for each imaging, the plurality of imaging conditions including a first condition corresponding to imaging of the first image and a second condition corresponding to imaging of the second image; The image processing unit obtains the first image from an image captured by the imaging unit under the first condition, and obtains the second image from an image captured by the imaging unit under the second condition.

Images