Observation head and imaging device

Abstract

The present invention provides a compact imaging device with excellent versatility that can accurately image the peripheral edges of objects to be imaged, such as semiconductor wafers, and an observation head suitable for miniaturizing the imaging device. [Solution] This invention relates to an observation head used for imaging the peripheral edge of an object to be imaged at a preset imaging position, and an imaging device using the observation head. In this observation head, the notch is configured to penetrate the peripheral edge from the radial direction of the substrate and surround the upper, side, and lower surfaces of the peripheral edge at the imaging position. Illumination light irradiated from a position away from the object to be imaged toward the imaging position is diffusely reflected by the first diffuser surface to generate first diffuse light, which simultaneously illuminates the upper, side, and lower surfaces of the peripheral edge.

Description

Technical Field

[0001] The present invention relates to an imaging device for imaging a peripheral portion of an object to be imaged such as a semiconductor wafer, and an observation head suitable for the imaging device.

Background Art

[0002] A processing system for performing various processes on the peripheral portion of an object to be imaged such as a semiconductor wafer is known. For example, in Patent Document 1, after a coating material is spread on a substrate, the bevel portion of the substrate is cleaned. Further, after the bevel cleaning step, an inspection step of inspecting the surface state of the bevel portion to determine the presence or absence of the coating material on the bevel portion is executed. This inspection step is executed by a device different from the device that executes the bevel cleaning step.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the system described in Patent Document 1 above, the substrate processing device that executes the bevel cleaning step and the inspection device that executes the inspection step are separated from each other. Therefore, a time difference occurs between the occurrence of a defect in the substrate processing device and the discovery of a defect in the inspection device. This may be a factor in reducing the yield.

[0005] Therefore, to resolve the above problem, it is conceivable to incorporate an inspection device into the substrate processing apparatus. However, the inspection device places a CMOS (Complementary Metal Oxide Semiconductor) camera on the periphery of the substrate and uses this camera to image the periphery of the substrate. Furthermore, when inspecting the surface condition of the bevel, a camera is required to observe the bevel from various directions, and a light source is required to illuminate the bevel from various directions corresponding to the camera. In other words, with conventional inspection devices, for example, when observing the top, side, and bottom surfaces of the bevel, components are required to illuminate the top surface, components to illuminate the side, and components to illuminate the bottom surface, making it difficult to incorporate an inspection device into the substrate processing apparatus.

[0006] This invention has been made in view of the above-mentioned problems, and aims to provide a compact imaging device with excellent versatility that can capture the peripheral edges of objects to be imaged, such as semiconductor wafers, and an observation head suitable for miniaturizing the imaging device. [Means for solving the problem]

[0007] A first aspect of the present invention is an observation head used for imaging the peripheral edge of an object to be imaged at a preset imaging position, comprising: a diffuse illumination unit having a first diffuse surface that diffusely reflects illumination light irradiated from a position away from the object to be imaged toward the imaging position to generate first diffuse light, and illuminating the peripheral edge with the first diffuse light; and a guide unit that guides the reflected light reflected from the peripheral edge illuminated by the first diffuse light to a position spaced away from the object to be imaged, wherein the diffuse illumination unit has a notch formed so as to enter the peripheral edge from the radial direction of the object to be imaged and enclose the upper, side and lower surfaces of the peripheral edge at the imaging position, and the first diffuse surface is provided adjacent to the notch so as to illuminate the upper, side and lower surfaces of the peripheral edge with the first diffuse light.

[0008] Furthermore, a second aspect of the present invention is an imaging device for imaging the peripheral portion of an object to be imaged, characterized by comprising: an observation head; a light source that irradiates illumination light from a position away from the object to be imaged toward the imaging position; and an imaging unit that receives reflected light guided by a guide unit at a distanced position to acquire an image of the peripheral portion.

[0009] In the invention configured in this way, illumination light irradiated from a position away from the object to be imaged toward the imaging position is incident on the diffuse illumination section of the observation head, generating first diffuse light, which illuminates the peripheral edge of the object to be imaged at the imaging position. This diffuse illumination section is configured such that the notched portion penetrates the peripheral edge of the object to be imaged from the radial direction, surrounding the upper, side, and lower surfaces of the peripheral edge at the imaging position, and the first diffuse light generated by the first diffuse surface illuminates the upper, side, and lower surfaces of the peripheral edge. [Effects of the Invention]

[0010] According to this invention, an observation head is used that converts illumination light into first diffuse light at the imaging position, simultaneously illuminating the upper, side, and lower surfaces of the periphery, and guiding the reflected light reflected from the periphery to a position spaced away from the object being imaged. As a result, the peripheral edges of objects to be imaged, such as semiconductor wafers, can be imaged well, and an imaging device that is compact and has excellent versatility can be obtained. [Brief explanation of the drawing]

[0011] [Figure 1] This figure shows a substrate processing system equipped with a first embodiment of the substrate processing apparatus according to the present invention. [Figure 2] This diagram schematically shows the configuration of the first embodiment of the substrate processing apparatus. [Figure 3] This is a plan view of a part of a substrate processing device, seen from above. [Figure 4] Figures 2 and 3 are block diagrams showing the electrical configuration of the substrate processing apparatus. [Figure 5] This is a perspective view showing the head of the imaging mechanism. [Figure 6] Figure 5 is a perspective view of the disassembled and assembled head unit. [Figure 7A] This is a diagram schematically showing the direction of light contributing to the top imaging. [Figure 7B] This is an enlarged partial cross-sectional view of Fig. 7A. [Figure 7C] This is a diagram schematically showing the direction of light contributing to the bottom imaging. [Figure 7D] This is a diagram schematically showing the direction of light contributing to the side imaging. [Figure 8] This is a diagram schematically showing an image of the peripheral portion and the adjacent region of the substrate imaged by the imaging unit. [Figure 9] This is a flowchart showing the substrate processing executed by the substrate processing apparatus shown in Fig. 1. [Figure 10] This is a flowchart showing the operation of acquiring the full peripheral image of the substrate using the imaging unit. [Figure 11] This is a schematic diagram showing an example of the full peripheral image after the bevel etching process acquired according to the operation of acquiring the full peripheral image shown in Fig. 10. [Figure 12] This is a schematic diagram showing an example of the residue emphasized image obtained by performing image processing to emphasize the residue on the full peripheral image. [Figure 13] This is a perspective view showing the head unit equipped in the second embodiment of the imaging apparatus according to the present invention. [Figure 14] This is an exploded perspective view of the head unit shown in Fig. 13. [Figure 15] This is a diagram schematically showing the state of attachment of the head unit shown in Fig. 13 to the arm.

Embodiments for Carrying Out the Invention

[0012] FIG. 1 is a diagram showing a substrate processing system equipped with a first embodiment of a substrate processing apparatus according to the present invention. The substrate processing system 200 includes a substrate processing unit 210 that performs processing on a substrate S, and an indexer unit 220 coupled to the substrate processing unit 210. The indexer unit 220 can hold a plurality of containers C (such as a FOUP (Front Opening Unified Pod) that houses a plurality of substrates S in a sealed state, a SMIF (Standard Mechanical Interface) pod, an OC (Open Cassette), etc.) for housing the substrate S in a container holding unit 221, and an indexer robot 222 for accessing the container C held in the container holding unit 221 to take out an unprocessed substrate S from the container C or store a processed substrate S in the container C. A plurality of substrates S are housed in each container C in a substantially horizontal posture. In this specification, the pattern formation surface (one main surface) on which a pattern is formed out of the two main surfaces of the substrate S is referred to as the "front surface", and the other main surface on which no pattern is formed on the opposite side is referred to as the "back surface". Also, the surface directed downward is referred to as the "lower surface", and the surface directed upward is referred to as the "upper surface". Further, in this specification, the "pattern formation surface" means a surface on which a concavo-convex pattern is formed in an arbitrary region on the substrate.

[0013] The indexer robot 222 includes a base portion 222a fixed to the apparatus housing, an articulated arm 222b provided rotatable about a vertical axis with respect to the base portion 222a, and a hand 222c attached to the tip of the articulated arm 222b. The hand 222c has a structure capable of placing and holding the substrate S on its upper surface. Since an indexer robot having such an articulated arm and a hand for holding a substrate is well-known, a detailed description thereof will be omitted.

[0014] The substrate processing unit 210 comprises a substrate transport robot 211 positioned approximately in the center in a plan view, and a plurality of processing units 1 arranged to surround the substrate transport robot 211. Specifically, the plurality of processing units 1 are arranged facing the space in which the substrate transport robot 211 is positioned. The substrate transport robot 211 randomly accesses these processing units 1 to receive the substrate S. Meanwhile, each processing unit 1 performs predetermined processing 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] Figure 2 is a schematic diagram showing the configuration of the first embodiment of the substrate processing apparatus. Figure 3 is a plan view of a part of the substrate processing apparatus viewed from above. Figure 4 is a block diagram showing the electrical configuration of the substrate processing apparatus shown in Figures 2 and 3. In Figures 2, 3, and the figures referenced below, the dimensions and number of parts may be exaggerated or simplified for ease of understanding. In addition, each figure is appropriately labeled with a coordinate system in which the Z axis is vertical and the XY plane is horizontal to clarify the directional relationships.

[0016] The substrate processing apparatus (processing unit) 1 comprises a rotating mechanism 2, a scattering prevention mechanism 3, a processing mechanism 4, a peripheral heating mechanism 5, and an imaging mechanism 6. Each of these parts 2 to 6 is housed in the internal space 101 of the processing chamber 100 and is electrically connected to a control unit 9 that controls the entire apparatus. Each of the parts 2 to 6 operates in accordance with instructions from the control unit 9.

[0017] The control unit 9 can be, for example, one similar to that of a general-purpose computer. That is, in the control unit 9, the CPU, acting as the main control unit, performs calculations according to the procedures described in the program, thereby controlling each part of the substrate processing apparatus 1. As a result, the substrate processing apparatus 1 supplies processing liquid to the peripheral edge of the upper surface of the substrate S within the processing chamber and performs bevel etching as an example of the "processing" of the present invention. The detailed configuration and operation of the control unit 9 will be described in detail later. In this embodiment, a control unit 9 is provided for each substrate processing apparatus 1, but it is also possible to configure the system so that one control unit controls multiple substrate processing apparatuses 1. Alternatively, the substrate processing apparatus 1 may be 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 the rotation direction AR1 (Figure 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 that passes through the center of the main surface of the substrate S. The rotation mechanism 2 is equipped with a spin chuck 21, which is a disc-shaped member smaller than the substrate S. The spin chuck 21 is positioned 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 vertically with its axis coincided with the rotation axis AX. A rotation drive unit (e.g., a motor) 23 is also connected to the rotation shaft portion 22. The rotation drive unit 23 rotates the rotation shaft portion 22 around its axis in response to a rotation command from the control unit 9. Therefore, the spin chuck 21 can rotate together with the rotation shaft portion 22 around the rotation axis AX. The rotation drive unit 23 and the rotation shaft unit 22 are responsible for rotating the spin chuck 21 around the rotation shaft AX.

[0019] A through-hole (not shown) is provided in the center of the spin chuck 21, communicating with the internal space of the rotating shaft 22. A pump 24 (Figure 4) is connected to the internal space via piping with a valve (not shown) interposed therein. The pump 24 and valve are electrically connected to the control unit 9 and operate in response to commands from the control unit 9. This allows negative 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 while the substrate S is placed on the upper surface of the spin chuck 21 in a nearly horizontal position, the spin chuck 21 attracts 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 becomes removable from the upper surface of the spin chuck 21. Also, when the suction of the pump 24 is stopped, the substrate S becomes able to move horizontally on the upper surface of the spin chuck 21.

[0020] As shown in Figure 3, the splash prevention mechanism 3 has a roughly cylindrical cup 31 that surrounds the outer circumference of the substrate S held by the spin chuck 21, and a liquid receiving portion 32 provided below the outer circumference of the cup 31. The cup 31 moves up and down when the guard drive unit 33 (Figure 4) is activated in response to a control command from the control unit 9. When the cup 31 is positioned in the lower position, as shown in Figure 2, the upper end of the cup 31 is positioned below the peripheral edge Ss of the substrate S held by the spin chuck 21. Conversely, when the cup 31 is positioned in the upper position, the upper end of the cup 31 is positioned above the peripheral edge Ss of the substrate S.

[0021] When the cup 31 is in the lower position, as shown in Figure 2, 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 when, for example, loading or unloading the substrate S into or out of the spin chuck 21.

[0022] On the other hand, when the cup 31 is in the upper position, the inner surface of the cup 31 surrounds the outer circumference of the substrate S held by the spin chuck 21. This prevents droplets of the processing liquid that are shaken off from the peripheral edge Ss of the substrate S during the bevel etching process described later from scattering into the processing chamber 100. It also ensures that the processing liquid is reliably collected. Specifically, as the substrate S rotates, droplets of the processing liquid that are shaken off from the peripheral edge Ss of the substrate S adhere to the inner surface of the cup 31 and flow downward, where they are collected by the liquid receiving section 32 located below the cup 31.

[0023] The processing mechanism 4 includes a base 41, a pivot shaft 42, an arm 43, and a processing liquid nozzle 44. The base 41 is fixed to the processing chamber 100. The pivot shaft 42 is rotatably mounted on the base 41. An arm 43 extends horizontally from the pivot shaft 42, and a processing liquid nozzle 44 is attached to its tip. As the pivot shaft 42 rotates in response to a control command from the control unit 9, the arm 43 swings, and the processing liquid nozzle 44 at the tip of the arm 43 moves between a retracted position (the position indicated by the dashed line in Figure 3) where it is retracted laterally from above the substrate S, and a processing position (the position indicated by the solid line in Figure 3) above the peripheral edge of the substrate S.

[0024] The processing liquid nozzle 44 is connected to the processing liquid supply unit 45 (Figure 4). When the processing liquid supply unit 45 supplies processing liquid to 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 the processing start position Ps. This processing start position Ps is a point on the path along which the peripheral edge Ss of the substrate S moves. Therefore, as the spin chuck 21 rotates while the processing liquid nozzle 44 discharges the processing liquid, each part of the peripheral edge Ss of the substrate S receives the processing liquid as it passes through the processing start position Ps. As a result, bevel etching is performed on the entire peripheral edge Ss of the substrate S using the processing liquid.

[0025] The peripheral heating mechanism 5 consists of an annular heater 51. The heater 51 contains a heating element that extends circumferentially along the lower peripheral edge of the substrate S. When a heating command is given to this heater 51 from the control unit 9, the peripheral edge Ss of the substrate S is heated from below by the heat emitted from the heating element. As a result, the temperature of the peripheral edge Ss is raised to a value suitable for the bevel etching process.

[0026] The imaging mechanism 6 corresponds to the first embodiment of the "imaging device" of the present invention. The imaging mechanism 6 includes a base 6A, a pivot shaft 6B, an arm 6C, a head drive unit 6D, a light source 6E, an imaging unit 6F, and a head unit 6G. The base 6A is fixed to the processing chamber 100. The pivot shaft 6B is rotatably mounted on the base 6A. An arm 6C extends horizontally from the pivot shaft 6B, and a head unit 6G is attached to its tip. When a control command is given from the control unit 9 to the head drive unit 6D (Figure 4) which drives the arm 6C, the head drive unit 6D swings the arm 6C in response to the command as shown by the dashed line in Figure 3. As a result, the head unit 6G attached to the tip of the arm 6C moves back and forth between a retracted position P1 (solid line position in Figure 3), where it is retracted from above to the side of the substrate S, and an imaging position P2 (dotted-dotted line position in Figure 3), where it images the peripheral edge Ss of the substrate S.

[0027] As shown in Figure 3, the light source 6E and the imaging unit 6F are located at a spaced position P3, which is spaced in the X direction from the imaging position P2. This spaced position P3 is spaced apart from the parts that perform bevel etching on the substrate S and cup 31 (rotating mechanism 2, splash prevention mechanism 3, processing mechanism 4, and peripheral heating mechanism 5). The light source 6E irradiates illumination light L1 from the outside of the cup 31 toward the imaging position P2. At this time, the cup 31 is positioned downwards, 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. This illumination light L1 is diffusely reflected by the head unit 6G. The peripheral edge Ss of the substrate S is illuminated by the diffuse light thus generated. Then, the reflected light L2 reflected from the peripheral edge 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 spaced position P3 and incident on the imaging unit 6F. As a result, the imaging unit 6F acquires an image of the peripheral area Ss of the substrate S and sends the image data to the control unit 9.

[0028] As described above, the head unit 6G receives illumination light L1 from the light source 6E, generates diffused light, and has both a diffuse illumination function that illuminates the peripheral edge Ss of the substrate S with this diffused light, and a guiding function that guides the reflected light L2 reflected from the peripheral edge Ss to the imaging unit 6F. The configuration and operation of the head unit 6G will be described below with reference to Figures 5 to 8.

[0029] Figure 5 is a perspective view showing the head of the imaging mechanism. Figure 6 is an exploded and assembled perspective view of the head shown in Figure 5. The head 6G includes a diffuse illumination section 61 having three diffuse surfaces 61a to 61c, a guide section 62 composed of three mirror members 62a to 62c, a holding section 63 having two diffuse surfaces 63a and 63b, and a support section 64. In Figure 5 (and in Figures 7A, 7C to 7D which will be explained later), dots are placed in the area corresponding to the holding section 63 to clearly indicate it. Also, the area indicated by the thick dashed line in Figure 5 (and in Figures 7A, 7C to 7D which will be explained later) is the area illuminated by the illumination light L1, that is, the illumination area by the light source 6E.

[0030] The holding portion 63 is made of, for example, PEEK (polyetheretherketone), and as shown in Figure 6, has a plate portion 631 extending in the horizontal direction Y perpendicular to the X direction, and a protruding portion 632 protruding in the (+X) direction on the (+Y) side of the plate portion 631, i.e., on the substrate side. In the holding portion 63, as shown in Figures 5 and 6, a notch 636 is provided that extends in the Y direction from the end face on the (+Y) side of the protruding portion 632 to a part of the plate portion 631. The vertical size of the notch 636 is wider than the thickness of the substrate S, and as shown in Figure 5, when the head portion 6G is positioned at the imaging position P2, the notch 636 extends into the peripheral edge Ss of the substrate S and the area further radially inward (to the right in the figure) from the peripheral edge Ss. In this positioned state, the vertically upper region, the region on the (-Y) side, and the vertically lower region of the notch 636 of the plate portion 631 face the upper surface Ssu, the side surface Sse, and the lower surface Ssd of the peripheral edge Ss of the substrate S, respectively. Mirror mounting portions 633 to 635 are provided in the vertically upper region, the region on the (-Y) side, and the vertically lower region of the notch 636, respectively. Mirror members 62a to 62c are attached to the mirror mounting portions 633 to 635, respectively. In this embodiment, the mirror members 62a to 62c are made of Si (silicon) considering chemical resistance and heat resistance.

[0031] On the other hand, in the protruding portion 632, an inclined surface is formed in the vertically upper region of the notch 636, sloping toward the mirror member 62a, and this inclined surface functions as a diffusion surface 63a. That is, the diffusion surface 63a diffusely reflects a portion of the illumination light L1, generating upward diffused light toward the upper surface Ssu of the peripheral edge Ss of the substrate S, and corresponds to an example of the "second upward diffusion surface" of the present invention. The diffused light generated at the diffusion surface 63a will be explained later with reference to Figure 7A, together with the diffused light generated at the diffusion surface 61a, which functions as the "first upward diffusion surface" of the present invention.

[0032] Furthermore, an inclined surface is formed in the vertically downward region of the notch 636, sloping toward the mirror member 62c, and this inclined surface functions as a diffusion surface 63b. That is, the diffusion surface 63b diffusely reflects a portion of the illumination light L1, generating downward diffused light toward the lower surface Ssd of the peripheral edge Ss of the substrate S, and corresponds to an example of the "second downward diffusion surface" of the present invention. The diffused light generated at the diffusion surface 63b will be explained later with reference to Figure 7C (upper surface region adjacent radially inward to the peripheral edge Ss), along with the diffused light generated at the diffusion surface 61c, which functions as the "first downward diffusion surface" of the present invention.

[0033] In this manner, the holding portion 63 to which the mirror members 62a to 62c are attached is integrated by being sandwiched between the diffuse illumination portion 61 located on its (+X) side and the support portion 64 located on its (-X) side.

[0034] The diffuse illumination section 61 is made of, for example, PTFE (polytetrafluoroethylene). As shown in Figures 5 and 6, the diffuse illumination section 61 has a plate shape extending in the horizontal direction Y, and a notch 611 is formed at the end on the (+Y) side. This notch 611 has a shape that is a U-shape rotated 90° clockwise when viewed from the (+X) side. In addition, the diffuse illumination section 61 has an inclined surface along the notch 611. The inclined surface is a tapered surface that is finished so that it slopes in the direction (-X) in which the illumination light L1 travels as it approaches the notch 611. In particular, the vertically upper region of the notch 611, the region on the (-Y) side, and the vertically lower region of this tapered surface function as diffuse surfaces 61a to 61c, respectively. As shown in Figure 5, the diffuse illumination unit 61 is positioned relative to the holding unit 63 such that the diffuse surfaces 61a to 61c are located in the illumination area by the light source 6E (the area indicated by the thick dashed line in Figure 5), and the diffuse surfaces 61a and 61c are adjacent to the diffuse surfaces 63a and 63b, respectively.

[0035] Figure 7A schematically shows the path of light contributing to top surface imaging. Figure 7B is a magnified cross-sectional view of Figure 7A. As shown in Figures 7A and 7B, the diffusion surfaces 61a and 63a diffusely reflect a portion of the illumination light L1, thereby generating top surface diffused light La toward the top surface of the substrate S including the peripheral portion Ss, and correspond to an example of the "first top surface diffused surface" of the present invention. Similarly, the diffusion surface 63a also generates top surface diffused light La. A portion of this top surface diffused light La is reflected by the top surface of the peripheral portion Ss and the adjacent region of the peripheral portion Ss (the top surface region adjacent radially inward to the peripheral portion Ss), generating reflected light L2. This reflected light L2 includes reflected light reflected from the upper surface Ssu of the peripheral portion Ss (see dotted arrow in Figure 7A) and reflected light reflected from the upper surface of the adjacent region of the peripheral portion Ss (see dashed arrow in Figure 7A). These reflected lights L2 are further reflected by the reflective surface 62a1 of the mirror member 62a and then guided to the separated position P3. In other words, the reflective surface 62a1 functions as the "upper reflective surface" of the present invention. The reflected light is then received by the imaging unit 6F. As a result, the imaging unit 6F is able to capture images of the upper surfaces of the peripheral portion Ss and adjacent regions (hereinafter referred to as "upper surface images").

[0036] Figure 7C schematically shows the propagation of light contributing to bottom surface imaging. The diffuse surfaces 61c and 63b are located below the diffuse surfaces 61a and 63a, with the substrate S in between, and illuminate the lower surface of the peripheral Ss and adjacent regions with bottom-surface diffused light. In other words, the diffuse surface 61c corresponds to an example of the "first bottom-surface" of the present invention, and as shown in Figure 7C, it generates bottom-surface diffused light Lc directed toward the lower surface of the substrate S, including the peripheral Ss, by diffusely reflecting a portion of the illumination light L1. The same applies to the diffuse surface 63b in generating bottom-surface diffused light Lc. Then, a portion of this bottom-surface diffused light Lc is reflected by the lower surface of the peripheral Ss and adjacent regions of the substrate S, generating reflected light L2. This reflected light L2 includes reflected light reflected from the lower surface Ssd of the peripheral portion Ss (see dotted arrow in Figure 7C) and reflected light reflected from the lower surface of the adjacent region of the peripheral portion Ss (see dashed arrow in Figure 7C). These reflected lights L2 are further reflected by the reflective surface 62c1 of the mirror member 62c and then guided to the separated position P3. In other words, the reflective surface 62c1 functions as the "downward reflective surface" of the present invention. The reflected light L2 is then received by the imaging unit 6F. As a result, the imaging unit 6F is able to capture images of the lower surface of the peripheral portion Ss and the adjacent region (hereinafter referred to as the "lower surface image").

[0037] Figure 7D schematically shows the propagation of light contributing to lateral imaging. As shown in Figure 7D, the diffusing surface 61b diffusely reflects a portion of the illumination light L1, generating lateral diffused light Lb directed toward the side surface Sse (Figure 5) of the substrate S, and corresponds to an example of the "lateral diffused surface" of the present invention. A portion of the lateral diffused light Lb is then reflected by the side surface Sse of the substrate S, generating reflected light L2. This reflected light L2 includes the reflected light reflected by the side surface Sse of the substrate S (see the dotted arrow in Figure 7A), and this reflected light is further reflected by the reflective surface 62b1 of the mirror member 62b before being guided to the separated position P3. In this way, the reflective surface 62a1 functions as the "lateral reflective surface" of the present invention.

[0038] The imaging unit 6F has an observation lens system composed of an object-side telecentric lens and a CMOS camera. Therefore, of the reflected light L2, only the light rays parallel to the optical axis of the observation lens system are incident on the sensor surface of the CMOS camera, and an image of the peripheral edge Ss and adjacent region of the substrate S is formed on the sensor surface. In this way, the imaging unit 6F images the peripheral edge Ss and adjacent region of the substrate S and acquires an image (= top image Ma + side image Mb + bottom image Mc) as shown in Figure 8. The imaging unit 6F then transmits the image data showing this image to the control unit 9. Figure 8 is a schematic diagram showing the images of the peripheral edge and adjacent region of the substrate captured by the imaging unit, where (a) shows the image before bevel etching and (b) shows the image after bevel etching. As is clear from these images, by analyzing these images, information such as the shape and etching status of the peripheral edge of the substrate S in the circumferential direction can be obtained. Based on this information, it is possible to inspect the 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, and the bevel etching results (etching width).

[0039] Therefore, 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 and performs (A) substrate inspection before bevel etching, (B) alignment, (C) bevel etching after alignment, and (D) substrate inspection after bevel etching. As shown in Figure 4, the control unit 9 has an arithmetic processing unit 91 that performs various calculations, a storage unit 92 that stores basic programs and image data, and an input display unit 93 that displays various information and accepts input from the operator. The control unit 9 controls each part of the substrate processing apparatus 1 as follows by having the arithmetic processing unit 91, which acts as the main control unit, perform calculations according to the procedures described in the program. In other words, as shown in Figure 4, the arithmetic processing unit 91 functions as a positioning control unit for positioning the head unit 6G, a full-peripheral image acquisition unit for acquiring a full-peripheral image, an eccentricity amount derivation unit for deriving the eccentricity amount of the substrate S from the full-peripheral image before bevel etching, a warpage amount derivation unit for deriving the warpage amount of the substrate S from the full-peripheral image before bevel etching, an etching width derivation unit for deriving the etching width from the full-peripheral image after bevel etching, and a residue analysis unit for analyzing residues from a residue-enhanced image obtained by image processing of the full-peripheral image.

[0040] In Figure 4, reference numeral 7 denotes an eccentricity correction mechanism that corrects the eccentricity of the substrate S with respect to the rotation axis AX by moving the substrate S by the above eccentricity amount. Since a conventionally known eccentricity correction mechanism can be used, a detailed explanation of the configuration of the eccentricity correction mechanism 7 is omitted here.

[0041] Figure 9 is a flowchart illustrating the substrate processing performed by the substrate processing apparatus shown in Figure 1. When the substrate processing apparatus 1 performs bevel etching on the substrate S, the arithmetic processing unit 91 uses the guard drive unit 33 to position the cup 31 in a lower position to prevent vignetting, where illumination light L1 and reflected light L2 are blocked by the cup 31. The arithmetic processing unit 91 also uses the head drive unit 6D to position the head unit 6G to the retracted position P1 (the position indicated by the dashed line in Figure 3). This creates sufficient transport space above the spin chuck 21 for the hand of the substrate transport robot 211 to enter. Once the completion of the transport space is confirmed, the arithmetic processing unit 91 requests the substrate transport robot 211 to load the substrate S and waits for the unprocessed substrate S to be brought into the substrate processing apparatus 1 and placed on the upper surface of the spin chuck 21, as shown in Figure 1. The substrate S is then placed on the spin chuck 21 (step S1). Following this, the pump 24 is activated and the substrate S is attracted and held in place by the spin chuck 21.

[0042] Once the loading of the substrate S is complete, the substrate transport robot 211 moves away from the substrate processing device 1. Subsequently, the arithmetic processing unit 91 acquires a full peripheral image of the substrate S (step S2). Figure 10 is a flowchart showing the operation of acquiring a full peripheral image of the substrate using the imaging unit. The arithmetic processing unit 91 controls each part of the imaging unit 6F and the spin chuck 21 according to the eccentricity acquisition program stored in the memory unit 92.

[0043] The arithmetic processing unit 91 rotates the spin chuck 21, which holds the substrate S by suction, to position the substrate S at the reference position (the position where the rotation angle is zero) (step S201). The arithmetic processing unit 91 moves the head unit 6G from the retracted position P1 to the imaging position P2 using the head drive unit 6D and positions it (step S202). As a result, as shown in Figure 5, the notch 636 of the head unit 6G is positioned so as to sandwich the peripheral edge Ss and adjacent areas of the substrate S. With this, the preparation for imaging is complete.

[0044] In the next step, S203, the arithmetic processing unit 91 turns on the light source 6E and starts diffuse illumination of the peripheral area Ss and adjacent areas of the substrate S by the head unit 6G. Subsequently, the arithmetic processing unit 91 gives a rotation command to the rotation drive unit 23 and starts rotating the substrate S held in the spin chuck 21 (step S204). After that, steps S205 to S207 are executed each time the substrate S rotates by a predetermined angle. In other words, the imaging unit 6F acquires an image, for example, as shown in Figure 8(a) (step S205). This image includes a top image Ma, a side image Mb, and a bottom image Mc, and the arithmetic processing unit 91 extracts each image Ma to Mc (step S206). Then, the arithmetic processing unit 91 stitches the images together while applying image processing such as rotation to each extracted image (step S207). This processing is executed until the substrate S completes one rotation around the rotation axis AX, that is, until "YES" is determined in step S208. This results in a full-peripheral image IM of the substrate S, which includes an upper surface full-peripheral image IMa obtained by unfolding the upper surface Ssu of the peripheral edge Ss of the substrate S in the circumferential direction, a side surface full-peripheral image IMb obtained by unfolding the side surface Sse in the circumferential direction, and a lower surface full-peripheral image IMc obtained by unfolding the lower surface Ssd in the circumferential direction.

[0045] In parallel with saving the full-peripheral image IM (step S209), the arithmetic processing unit 91 issues a rotation stop command to the rotation drive unit 23, stopping the rotation of the substrate S held in the spin chuck 21, and also turning off the light source 6E, thus stopping the illumination (step S210). Subsequently, the arithmetic processing unit 91 moves the head unit 6G from the imaging position P2 to the retracted position P1 using the head drive unit 6D, and positions it (step S211).

[0046] Of the full-peripheral images IM obtained in this way, the top full-peripheral image IMa or the bottom full-peripheral image IMc contains information reflecting the eccentricity of the substrate S with respect to the rotation axis AX. In addition, the side full-peripheral image IMb contains information reflecting the warping of the substrate S.

[0047] Therefore, in this embodiment, the arithmetic processing unit 91 calculates the eccentricity and warpage of the substrate S from the full-peripheral image IM (step S3), and determines whether at least one of these calculated values ​​(=eccentricity and warpage) is within the allowable range (step S4). Note that conventional methods can be used for calculating the eccentricity and warpage, so a description of these calculation methods will be omitted here.

[0048] If, in step S4, the calculation unit 91 determines that the calculated value exceeds the allowable value ("NO" in step S4), it displays on the input display unit 93 that the substrate S is defective (step S5) and stops the bevel etching process on the substrate S. On the other hand, if the eccentricity and warpage are within the allowable values ​​and the substrate S is confirmed to be good quality, the calculation unit 91 performs an alignment process to correct the eccentricity of the substrate S (step S6). More specifically, the calculation unit 91 rotates the spin chuck 21 to position the substrate S at a rotational position where alignment correction by the eccentricity correction mechanism 7 can be performed, and then stops the suction of the pump 24 to allow the substrate S to move horizontally on the upper surface of the spin chuck 21. After the calculation unit 91 performs alignment correction by the eccentricity correction mechanism 7, it restarts the suction of the pump 24 to hold the alignment-corrected substrate S in place with the spin chuck 21. As a result, the center of the main surface of the substrate S is located on the vertical rotation axis AX, and the eccentricity is eliminated.

[0049] Next, the arithmetic processing unit 91 raises the cup 31 to an upward position using the guard drive unit 33. As a result, the inner surface of the cup 31 surrounds the outer circumference of the substrate S held by the spin chuck 21. Once the preparation for supplying the processing liquid to the substrate S is complete, the arithmetic processing unit 91 issues a rotation command to the rotation drive unit 23, and starts the rotation of the spin chuck 21 that holds the substrate S. The arithmetic processing unit 91 also activates the heater 51 of the peripheral heating mechanism 5. Subsequently, the arithmetic processing unit 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 edge Ss of the substrate S receives the processing liquid as it passes through the processing start position Ps. Consequently, bevel etching is performed on the entire peripheral edge Ss of the substrate S using the processing liquid (step S7). Then, when the arithmetic processing unit 91 detects the elapsed processing time required for the bevel etching process of the substrate S, it issues a command to stop supplying the processing liquid to the processing liquid supply unit 45, and stops the discharge of the processing liquid. Subsequently, the arithmetic processing unit 91 issues a command to stop rotation to the rotary drive unit 23, stopping the rotation of the spin chuck 21 and also stopping the heating by the heater 51.

[0050] Once the bevel etching process is complete, the arithmetic processing unit 91, similar to step S2, uses the imaging mechanism 6 to acquire a full-peripheral image IM after the bevel etching process, such as the one shown in Figure 11 (step S8). This full-peripheral image IM includes a top full-peripheral image IMa, a side full-peripheral image IMb, and a bottom full-peripheral image IMc. In particular, the top full-peripheral image IMa includes an image of the bevel-etched region. In this embodiment, the arithmetic processing unit 91 inspects the substrate S based on the top full-peripheral image IMa of the full-peripheral image IM (step S9). That is, it inspects whether the peripheral portion Ss of the substrate S has been bevel-etched with a desired etching width, displays the inspection result on the input display unit 93, and stores it in the storage unit 92. Furthermore, by applying image processing to enhance the residue to the full-peripheral image IM, the arithmetic processing unit 91 acquires a residue-enhanced image IMr, such as the one shown in Figure 12. Then, based on the residue-enhanced image IMr, the arithmetic processing unit 91 detects the residue R remaining in the peripheral area Ss and adjacent regions of the substrate S, measures the number of residues for each size, and reports it as one of the bevel etching results (residue analysis).

[0051] After inspection, the arithmetic processing unit 91 requests the substrate transport robot 211 to unload the substrate S, and the processed substrate S is discharged from the substrate processing device 1 (step S10). This series of steps is repeated.

[0052] As described above, in this embodiment, the light source 6E and the imaging unit 6F are positioned at a spaced position P3 away from each part of the apparatus that performs bevel etching, while only the head unit 6G is positioned at the imaging position P2. The light source 6E irradiates illumination light L1 towards the illumination area of ​​the head unit 6G, and guides the reflected light L2 reflected from the peripheral edge Ss and adjacent areas of the substrate S to the imaging unit 6F, thereby capturing an image of the peripheral edge Ss. Therefore, the peripheral edge Ss can be captured in good quality.

[0053] Furthermore, the head unit 6G can be positioned only at the imaging position P2, while the light source 6E and imaging unit 6F are positioned away from the various parts of the device that perform bevel etching (=rotation mechanism 2 + splash prevention mechanism 3 + processing mechanism 4 + peripheral heating mechanism 5). Therefore, the imaging mechanism 6 can be incorporated into a narrow area while avoiding interference with the various parts of the device, resulting in excellent versatility.

[0054] Furthermore, the imaging position P2 is under the environment of the processing solution used for bevel etching and the heating environment provided by the heater 51. Considering this, the head unit 6G is made of a material with chemical resistance and heat resistance, such as PEEK, PTFE, and Si. Therefore, the substrate processing apparatus 1 can stably capture images of the peripheral edge Ss of the substrate S. As a result, the eccentricity, warpage, and etching width of the substrate S can be detected with high accuracy, resulting in excellent inspection accuracy. Additionally, residue analysis can be performed with high accuracy.

[0055] Furthermore, by using the head unit 6G, diffuse illumination can be applied to the upper surface Ssu, side surface Sse, and lower surface Ssd of the peripheral edge Ss of the substrate S, and the upper, side, and lower images can be captured simultaneously. Therefore, the peripheral edge Ss of the substrate S can be imaged from multiple angles with excellent efficiency.

[0056] Figure 13 is a perspective view showing a head unit equipped in a second embodiment of the imaging device according to the present invention. Figure 14 is an exploded and assembled perspective view of the head unit shown in Figure 13. Figure 15 is a schematic diagram showing the state in which the head unit shown in Figure 13 is attached to the arm. There are two main differences between this second embodiment and the first embodiment. First, the diffusion surfaces 61d and 61e, which correspond to the diffusion surfaces 63a and 63b that were provided on the holding unit 63, are provided on the diffusion illumination unit 61, while the diffusion surfaces 63a and 63b are removed from the holding unit 63. Second, the diffusion illumination unit 61 and the holding unit 63 are configured to fit together and be integrated, while the support unit 64 is omitted. Other configurations are basically the same as those of the first embodiment. Therefore, the same reference numerals are used for the same configurations and their descriptions are omitted.

[0057] In the second embodiment, as shown in Figure 13, the end on the (+Y) side has a roughly C-shaped notch 611 when viewed from the (+X) side. In addition, the diffuse illumination section 61 has an inclined surface along the notch 611. The inclined surface is a tapered surface that slopes in the direction of the illumination light L1 (-X) as it approaches the notch 611. In particular, the vertically upper region, the region on the (-Y) side, and the vertically lower region of this tapered surface function as diffuse surfaces 61a to 61c, respectively. Also, the diagonally upper region and diagonally lower region in the (+Y) direction function as diffuse surfaces 61d and 61e. In other words, the diffuse surfaces 61d and 61e function similarly to the diffuse surfaces 63a and 63b in the first embodiment, and the diffuse surfaces are concentrated in the diffuse illumination section 61.

[0058] In accordance with this concentration of diffusion surfaces, the protruding portion 632 is removed from the holding portion 63. Furthermore, the holding portion 63 is finished in a shape that allows it to be mutually fitted with the diffusion illumination portion 61. That is, the diffusion illumination portion 61 and the holding portion 63 are integrated while holding the mirror members 62a to 62c by being mutually fitted. In this way, the head portion 6G is constructed with fewer parts than in the first embodiment. As shown in Figure 15, the head portion 6G is positioned at the imaging position P2 with its (-Y) side end attached to the arm 6C. Then, before the bevel etching process (step S2) and after the process (step S8), the diffusion illumination portion 61 of the head portion 6G diffusely reflects the illumination light L1 from the light source 6E, illuminating the peripheral portion Ss and adjacent areas of the substrate S with diffuse light La to Lc. In addition, the guide portion 62 of the head portion 6G further reflects the reflected light L2 reflected from the peripheral portion Ss and adjacent areas and guides it to the imaging portion 6F. Then, the imaging unit 6F captures images of the peripheral area Ss and adjacent regions.

[0059] As described above, the same effects and advantages as in the first embodiment can be obtained in the second embodiment as well. Furthermore, in the second embodiment, the head portion 6G is constructed with fewer parts than in the first embodiment. Therefore, the manufacturing cost of the imaging mechanism 6 can be reduced.

[0060] Furthermore, since the diffusion surfaces 61a and 61d, corresponding to the "first upward diffusion surface" and "second upward diffusion surface" of the present invention, respectively, are located on the same tapered surface, more advantageous effects can be obtained compared to the first embodiment. That is, in the first embodiment, the diffusion surfaces 61a and 63a correspond to the "first upward diffusion surface" and "second upward diffusion surface" of the present invention, respectively, and are made of different materials (PTFE and PEEK) and are provided on independent parts (diffusion illumination section 61, holding section 63). Therefore, a relatively large illuminance distribution may occur on the upper surface Ssu of the peripheral edge Ss of the substrate S. In contrast, in the second embodiment, since they are made of the same material (PTFE) and are provided on a continuous tapered surface, the illuminance distribution can be suppressed, and a better upper surface full peripheral image IMa can be obtained. The same applies to the lower surface.

[0061] In the embodiment described above, a substrate S such as a semiconductor wafer corresponds to an example of the "object to be imaged" in the present invention. The separated position P3 corresponds to an example of the "position away from the object to be imaged" in the present invention. The rotation direction AR1 corresponds to an example of the "constant direction" in the present invention. The rotation mechanism 2 functions as the "moving unit" in the present invention. The full-edge image acquisition unit functions as the "image acquisition unit" in the present invention. The eccentricity amount derivation unit, the warpage amount derivation unit, the etching width derivation unit, and the residue analysis unit function as the "inspection unit" in the present invention. Thus, in this embodiment, the combination of the rotation mechanism 2, the imaging mechanism 6, and the calculation processing unit 91 functions as the "inspection device" in the present invention.

[0062] It should be noted that the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention. For example, in the embodiments, the lengths of the upper diffusion surfaces 61a, 61d, 63a, the lower diffusion surfaces 61c, 61e, 63b, and the mirror members 62a, 62c in the Y direction are set to correspond to the bevel etching width of the substrate S, but the lengths of each part may be changed according to the range to be imaged by the imaging mechanism 6, for example, as shown in Figure 15. Alternatively, a head unit 6G with Y-direction lengths of the diffusion surfaces and mirror members that are different from each other may be prepared and configured to be selected and used according to the imaging target range. Furthermore, if a head unit 6G with Y-direction lengths of the diffusion surfaces that are different from each other is prepared, the diffusion surface of the head unit 6G may be composed of a continuous curved surface. Also, if a head unit 6G with Y-direction lengths of the diffusion surfaces that are different from each other is prepared, a part of the diffusion surface of the head unit 6G may be composed of a flat surface.

[0063] Furthermore, in the above embodiment, the observation lens system of the imaging unit 6F is composed of 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 composed of other lenses.

[0064] Furthermore, in the above embodiment, the diffuse illumination unit 61 and the holding unit 63 are subjected to the environment of the processing solution used for bevel etching and the heating environment provided by the heater 51, and are therefore made of materials that have chemical resistance and heat resistance. The diffuse illumination unit 61 and the holding unit 63 are made of PTFE and PEEK, respectively, but the constituent materials are not limited to these. The diffuse illumination unit 61 may be made of a material other than PTFE that has chemical resistance and heat resistance. The holding unit 63 may be made of a material other than PEEK that has chemical resistance and heat resistance. The diffuse illumination unit 61 and the holding unit 63 may be configured such that a fluororesin material such as PFA is coated on the surface of a metal material, resin material, or ceramic material, for example. Also, although the diffuse illumination unit 61 and the holding unit 63 are made of different materials, they may be made of the same material. Furthermore, when the diffuse illumination unit 61 and the holding unit 63 are used in an environment where chemical resistance and heat resistance are not required, the constituent materials are not limited. The diffuse illumination section 61 and the holding section 63 may be made of materials that do not have chemical resistance or heat resistance.

[0065] Furthermore, the configuration of the diffusion surfaces 61a to 61c, diffusion surfaces 61d, 61e of the diffusion illumination unit 61, and the diffusion surfaces 63a, 63b of the holding unit 63 is not limited. For example, if 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, diffusion surfaces 61d, 61e, or diffusion surfaces 63a, 63b may be made of a metal material with a shot-blasted surface.

[0066] Furthermore, the mirror members 62a to 62c are not limited to Si (silicon). In other words, other materials may be used as long as they have chemical resistance to the processing solution and heat resistance to the processing temperature. For example, the mirror members 62a to 62c may be configured in which a metallic material is deposited on the surface of a material that has chemical resistance and heat resistance. Also, when the mirror members 62a to 62c are used in an environment where chemical resistance and heat resistance are not required, the constituent materials are not limited. The mirror members 62a to 62c may be composed of materials that do not have chemical resistance and heat resistance. For example, the mirror members 62a to 62c may be configured in which a metallic material is deposited on the surface of a material that does not have chemical resistance and heat resistance.

[0067] Furthermore, in the above embodiment, a full-peripheral image IM (Figure 11) is always acquired, but the image to be acquired may be selected depending on the inspection content. For example, when inspecting the eccentricity of the substrate S, the system may be configured to acquire only the top surface full-peripheral image IMa. Also, when inspecting the warp of the substrate S, the system may be configured to acquire only the side surface full-peripheral image IMb. In addition, although a peripheral image for one rotation of the substrate S is acquired, it is not limited to the entire periphery, and for example, the system may be configured to acquire peripheral images for less than one rotation or multiple rotations depending on the inspection content.

[0068] Furthermore, in the above embodiment, the imaging mechanism 6 is fixed in place while the substrate S, which is the object to be imaged, is moved to image the peripheral portion. However, the system may be configured to move the imaging mechanism 6 while the substrate S is fixed. Alternatively, both the substrate S and the imaging mechanism 6 may be moved. In other words, the system may be configured to image the peripheral portion of the object to be imaged by the imaging device (imaging mechanism 6) while the object to be imaged (substrate S) is moved relative to the imaging device (imaging mechanism 6).

[0069] Furthermore, in the above embodiment, an imaging mechanism 6 corresponding to the imaging device according to the present invention is incorporated into a substrate processing apparatus 1 that bevel-etches the peripheral edge Ss of the substrate S, but the application of the imaging device (imaging mechanism 6) is not limited to this. The present invention can also be applied to imaging devices that image the peripheral edge of an object to be imaged, and inspection techniques that inspect the object to be imaged based on the peripheral edge image captured by the imaging device. In addition, the imaging mechanism 6 corresponding to the imaging device according to the present invention and the inspection apparatus can also be applied, for example, to a substrate processing apparatus that supplies a coating removal liquid to the peripheral edge of a substrate S on which a coating film has been formed, in order to remove the coating film from the peripheral edge of the substrate S. [Industrial applicability]

[0070] This invention can be applied to imaging devices in general that image the peripheral edges of objects to be imaged, such as semiconductor wafers, and to observation heads in general that can be equipped on such imaging devices. [Explanation of Symbols]

[0071] 6…Imaging mechanism (imaging device) 6F…Imaging Unit 6G…Head unit 61... Diffused lighting section 61a...First upward diffusion surface 61b... Lateral diffusion surface 61c...First downward diffusion surface 61d...Second upward diffusion surface 61e...Second downward diffusion surface 62... Guide section 62a~62c...Mirror components 62a1…Upper reflective surface 62b1…Side reflective surface 62c1…Downward reflective surface 63...Holding part 63a...Second upward diffusion surface 63b...Second downward diffusion surface L1…Illumination light L2…Reflected light La... Upper diffused light Lb...side diffused light Lc...bottom diffused light P2...Imaging position P3…Separated position S... Circuit board Ss... Peripheral edge (of the circuit board) SSD… (The lower surface of the peripheral edge) Sse... (periphery) side Ssu... (the upper surface of the peripheral edge)

Claims

1. An observation head used for imaging the peripheral portion of an object to be imaged at a preset imaging position, A diffuse illumination unit has a first diffuse surface that diffusely reflects illumination light irradiated from a position away from the object to be imaged toward the imaging position to generate first diffuse light, and illuminates the peripheral portion with the first diffuse light, The system includes a guide unit that guides the reflected light reflected from the peripheral portion illuminated by the first diffuse light to a position separated from the object to be imaged, The diffuse illumination unit has a notch that extends from the radial direction of the object to be imaged into the peripheral edge and is formed to enclose the upper surface, side surface, and lower surface of the peripheral edge at the imaging position. The first diffusing surface is provided adjacent to the notch so as to illuminate the upper surface, side surface, and lower surface of the peripheral edge with the first diffused light. Observation head.

2. An observation head according to claim 1, An observation head further comprising a holding part that integrally holds the diffuse illumination part and the guide part.

3. An observation head according to claim 2, The holding portion has a second diffusing surface that diffusely reflects the illumination light to generate a second diffused light, and illuminates the peripheral portion with the second diffused light. The guide portion is an observation head that guides the reflected light reflected from the peripheral portion illuminated by the first diffuse light and the second diffuse light to the separated position.

4. An observation head according to claim 1, The notch, when recessed into the peripheral edge, has an upper surface-facing portion, a side surface-facing portion, and a lower surface-facing portion, respectively, that face the upper surface, side surface, and lower surface of the peripheral edge. The first diffusion surface is An upper diffusion surface provided adjacent to the upper surface facing portion, A lateral diffusion surface provided adjacent to the aforementioned side-facing portion in the radial direction, A downward diffusion surface provided adjacent to the lower surface facing portion, Includes, The aforementioned guide section is An upper mirror member is positioned in the vertical direction between the upper surface of the peripheral edge and the portion facing the upper surface, and reflects the first reflected light reflected from the upper surface. A side mirror member is positioned in the radial direction between the side surface of the peripheral edge and the portion facing the side surface, and reflects the second reflected light reflected by the side surface. A lower mirror member is positioned in the vertical direction between the lower surface of the peripheral edge and the portion facing the lower surface, and reflects the third reflected light reflected from the lower surface. An observation head having [a certain feature].

5. An observation head according to claim 4, The direction in which the upper mirror member guides the first reflected light, the direction in which the side mirror member guides the second reflected light, and the direction in which the lower mirror member guides the third reflected light are the same. An observation head in which the light guide destinations of the first reflected light by the upper mirror member, the second reflected light by the side mirror member, and the third reflected light by the lower mirror member are all at the separated positions.

6. An observation head according to claim 4, An observation head in which the upward diffusion surface, the lateral diffusion surface, and the downward diffusion surface are provided continuously with respect to each other.

7. An imaging device for imaging the peripheral portion of an object to be imaged, An observation head according to any one of claims 1 to 6, A light source that illuminates the imaging position from a position away from the object to be imaged, An imaging unit that receives the reflected light guided by the guide unit at the separated position to acquire an image of the peripheral portion, An imaging device characterized by comprising:

Images