Observation device, observation method and substrate processing device

Abstract

This invention has, for example, a configuration in which an illumination optical system emits, as primary illumination light, p-polarized light that has been emitted from a first polarizer, and thus uses only p-polarized light to observe a portion to be observed (including a peripheral portion of a substrate). In a state in which a p-polarized light observation requirement is satisfied as above, the angle of incidence of the primary illumination light with respect to a diffusion illumination unit is equal to or close to the Brewster's angle, and therefore the intensity of p-polarized light which is specularly reflected by the diffusion illumination unit is not more than 10% of the intensity of diffusion light generated by the diffusion illumination unit (specular reflection suppression requirement). Satisfying both of these requirements (the p-polarized light observation requirement and the specular reflection suppression requirement) results in suppression of influence of the specular reflection light and improvement of the quality of an observation image.

Description

Observation device, observation method, and substrate processing apparatus

[0001] The present invention relates to an observation technique for observing an object to be observed, such as a semiconductor wafer, and a substrate processing apparatus that utilizes the observation technique.

[0002] The disclosures in the specifications, drawings and claims of the following Japanese applications are incorporated herein by reference in their entirety: Japanese Patent Application No. 2023-152743 (filed September 20, 2023).

[0003] There are known processing systems that perform various processes on the peripheral edge of an object to be observed, such as a semiconductor wafer. For example, in Patent Document 1, a coating material is spread on a substrate, and then the bevel portion of the substrate is cleaned. After the bevel cleaning process, an inspection process is performed in which the surface condition of the bevel portion is observed to determine whether or not the coating material is present on the bevel portion. This inspection process is performed using an apparatus different from the apparatus that performs the bevel cleaning process.

[0004] JP 2017-139492 A

[0005] In the system described in Patent Document 1, the substrate processing apparatus that performs the bevel cleaning process and the inspection apparatus that performs the inspection process are separated from each other. This causes a time lag between when a defect occurs in the substrate processing apparatus and when the defect is discovered by the inspection apparatus. This can result in a decrease in yield.

[0006] To solve the above problem, it has been considered to incorporate an observation device into a substrate processing apparatus. However, the observation device uses a complementary metal oxide semiconductor (CMOS) camera positioned around the periphery of the substrate to observe the periphery of the substrate. Furthermore, inspecting the surface condition of the beveled portion requires a camera for observing the beveled portion from various directions and a light source for illuminating the beveled portion from various directions corresponding to the camera. In other words, conventional observation devices require relatively large components positioned near the periphery of the substrate, making it difficult to incorporate the observation device into a substrate processing apparatus.

[0007] The present invention has been made in consideration of the above-mentioned problems, and has as its object to provide an observation apparatus and an observation method that can satisfactorily observe an observation portion such as the peripheral portion of a semiconductor wafer, as well as a substrate processing apparatus equipped with the observation apparatus.

[0008] A first aspect of the present invention is an observation device for observing an observation portion of an observation object, comprising: an illumination optical system that irradiates a vicinity of the observation portion with primary illumination light; a head unit that has a diffusion illumination unit that diffuses the primary illumination light in the vicinity of the observation portion and irradiates and illuminates the observation portion with diffused light generated by the diffusion illumination unit as secondary illumination light; and an observation optical system that receives light reflected by the observation portion illuminated with the secondary illumination light to observe the observation portion, wherein the illumination optical system has a light source unit that emits unpolarized light and a first polarizer that transmits only p-polarized light of the unpolarized light emitted from the light source unit, and a first condition is that the p-polarized light emitted from the first polarizer is irradiated as the primary illumination light, and the illumination optical system emits unpolarized light as the primary illumination light. and a second condition is that the observation optical system has a second polarizer that transmits only p-polarized light of the light reflected by the observed area and receives the p-polarized light emitted from the second polarizer as reflected light, and a third condition is that the illumination optical system has a light source unit that emits p-polarized light as primary illumination light, whereby one of the first to third conditions is satisfied and the illumination optical system is positioned with respect to the head unit so that the angle of incidence of the primary illumination light on the diffuse illumination unit is within a range from a lower limit angle that is smaller than the Brewster's angle to an upper limit angle that is larger than the Brewster's angle, and the intensity of the p-polarized light specularly reflected by the diffuse illumination unit is 10% or less of the intensity of the diffuse light generated by the diffuse illumination unit.

[0009] A second aspect of the present invention is a method for observing an observation portion of an object under observation, comprising: an illumination step of irradiating a diffuse illumination portion of a head portion positioned near the observation portion with primary illumination light from an illumination optical system, thereby irradiating the observation portion with diffused light generated by the diffuse illumination portion as secondary illumination light, and an observation step of receiving light reflected from the observation portion illuminated by the secondary illumination light, and observing the observation portion; wherein the illumination step is performed in a state in which the illumination optical system is positioned with respect to the head portion so that the angle of incidence of the primary illumination light on the diffuse illumination portion is within a range from a lower limit angle smaller than the Brewster's angle to an upper limit angle larger than the Brewster's angle, so that the intensity of the p-polarized light specularly reflected by the diffuse illumination portion is 10% or less of the intensity of the diffuse light generated by the diffuse illumination portion; and wherein the observation step is a step of receiving light reflected from the observation portion as reflected light when only p-polarized light is irradiated as the primary illumination light in the illumination step, while receiving only p-polarized light from the light reflected from the observation portion as reflected light when unpolarized light is irradiated as the primary illumination light in the illumination step.

[0010] A third aspect of the present invention is a substrate processing apparatus comprising: a rotation mechanism that holds and rotates a substrate; a processing mechanism that supplies a processing liquid to the peripheral edge of the substrate rotated by the rotation mechanism to process the peripheral edge of the substrate; and an observation device that observes the peripheral edge before or after processing the peripheral edge, wherein the observation device comprises: an illumination optical system that irradiates the vicinity of the peripheral edge with primary illumination light; and a head unit that has a diffusion illumination unit that diffuses the primary illumination light in the vicinity of the peripheral edge, and irradiates and illuminates the peripheral edge with the diffused light generated by the diffusion illumination unit as secondary illumination light; and an observation optical system that receives light reflected by the peripheral edge illuminated with the secondary illumination light to observe the peripheral edge, wherein the illumination optical system has a light source unit that emits unpolarized light, and a first polarizer that transmits only p-polarized light of the unpolarized light emitted from the light source unit, and The first condition is that the illumination optical system irradiates the primary illumination light as bright light, the second condition is that the illumination optical system has a light source unit that emits unpolarized light as primary illumination light, the observation optical system has a second polarizer that transmits only p-polarized light of the light reflected by the observed area and receives the p-polarized light emitted from the second polarizer as reflected light, and the third condition is that the illumination optical system has a light source unit that emits p-polarized light as primary illumination light, and when one of the first to third conditions is satisfied, the illumination optical system is positioned with respect to the head unit so that the angle of incidence of the primary illumination light on the diffuse illumination unit is within a range from a lower limit angle smaller than the Brewster's angle to an upper limit angle larger than the Brewster's angle, the intensity of the p-polarized light specularly reflected by the diffuse illumination unit is 10% or less of the intensity of the diffuse light generated by the diffuse illumination unit.

[0011] In these inventions, the head unit is positioned near the observation area (including the peripheral edge of the substrate). Primary illumination light is irradiated onto the diffuse illumination unit of the head unit, and the diffused light generated by the diffuse illumination unit is irradiated onto the observation area as secondary illumination light. A portion of the diffused light is reflected from the observation area illuminated with the diffused light. The reflected light is then incident on the observation optical system, allowing the observation area to be observed.

[0012] When the secondary illumination light is composed solely of the diffused light, a good image of the observation area is obtained by receiving the reflected light. However, as will be described later, unless special consideration is given, the secondary illumination light also includes light specularly reflected by the diffuse illumination area (see the thick solid line in FIG. 10 ). This specularly reflected light has a higher brightness than the diffused light. Therefore, when the observation area is observed using secondary illumination light including specularly reflected light, bright lines resulting from this light are included in the observation image, which can lead to a deterioration in the quality of the observation image (see the comparative example (a) in FIG. 11 ).

[0013] Therefore, in the invention configured as described above, one of the first to third conditions is satisfied, and the observation area (including the peripheral edge of the substrate) is observed using only p-polarized light. When the p-polarized light observation requirement is satisfied, the angle of incidence of the primary illumination light on the diffuse illumination unit is further configured to be within the above range, so that the intensity of the p-polarized light specularly reflected by the diffuse illumination unit is 10% or less of the intensity of the diffused light generated by the diffuse illumination unit (specular reflection suppression requirement). By satisfying both of these requirements (p-polarized light observation requirement and specular reflection suppression requirement), the inclusion of specularly reflected light in the secondary illumination light is suppressed, improving the quality of the observation image.

[0014] According to the present invention, an observation apparatus capable of observing an observation portion of an object under observation in a satisfactory manner can be obtained. Furthermore, the use of this observation apparatus makes it easy to incorporate it into a substrate processing apparatus.

[0015] Not all of the multiple components of each of the above-described aspects of the present invention are essential, and in order to solve some or all of the above-described problems or achieve some or all of the effects described in this specification, it is possible to modify, delete, or replace some of the multiple components with new components, or to delete some of the limitations, as appropriate. Furthermore, in order to solve some or all of the above-described problems or achieve some or all of the effects described in this specification, it is possible to combine some or all of the technical features included in one aspect of the present invention described above with some or all of the technical features included in another aspect of the present invention described above to form an independent aspect of the present invention.

[0016] 1 is a diagram showing a substrate processing system equipped with an embodiment of a substrate processing apparatus according to the present invention. FIG. 1 is a diagram showing a schematic configuration of a substrate processing apparatus. FIG. 2 is a plan view of a part of the substrate processing apparatus seen from above. FIG. 3 is a diagram illustrating an example of the shape of a peripheral portion of a substrate to be imaged. FIG. 4 is a block diagram showing the electrical configuration of the substrate processing apparatus shown in FIGS. 2 and 3. FIG. 5 is a perspective view showing a head unit of an imaging mechanism. FIG. 6 is a perspective view showing a head unit of an imaging mechanism. FIG. 7 is a diagram showing a schematic view of the direction of travel of light that contributes to top surface imaging. FIG. 8 is a diagram showing a schematic view of the direction of travel of light that contributes to side surface imaging. FIG. 9 is a diagram showing a schematic view of the direction of travel of light that contributes to side surface imaging. FIG. 10 is a diagram showing a schematic view of an image of the peripheral portion of a substrate imaged by an imaging unit. FIG. 11 is a diagram showing a schematic view of the generation of specularly reflected light and diffused light when unpolarized primary illumination light is irradiated onto a diffuse illumination unit. FIG. 12 is a diagram showing an example of an image obtained by imaging the peripheral portion of a substrate using unpolarized primary illumination light and p-polarized primary illumination light, respectively. 10A and 10B are diagrams showing the characteristics of specularly reflected light intensity corresponding to the incident angle θ of p-polarized light and s-polarized light (see FIG. 10A), and the characteristics of diffused light intensity corresponding to the incident angle θ of p-polarized light (see FIG. 10B). 11A is a diagram showing an example of an illumination optical system equipped in a substrate processing apparatus according to the present invention. 12A is a diagram showing an example of a drive circuit for a light-emitting

[0017] 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 unit 210 that processes substrates S and an indexer unit 220 coupled to the substrate processing unit 210. The indexer unit 220 includes a container holder 221 that can hold a plurality of containers C for accommodating substrates S (e.g., FOUPs (Front Opening Unified Pods), SMIF (Standard Mechanical Interface) pods, and OCs (Open Cassettes) that hermetically accommodate a plurality of substrates S), and an indexer robot 222 that accesses the containers C held by the container holder 221 to remove unprocessed substrates S from the container C and store processed substrates S in the container C. Each container C accommodates a plurality of substrates S in a substantially horizontal position.

[0018] In this specification, the pattern-forming 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-forming surface" refers to the surface of the substrate on which a concave-convex pattern is formed in any region.

[0019] The indexer robot 222 comprises a base 222a fixed to the apparatus housing, an articulated arm 222b rotatable about 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 a detailed description thereof will be omitted.

[0020] The substrate processing section 210 includes a substrate transfer robot 211 disposed approximately in 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 as needed to hand over substrates 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.

[0021] FIG. 2 is a diagram showing a schematic configuration of a substrate processing apparatus. FIG. 3 is a plan view of a portion 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 the electrical configuration of the substrate processing apparatus shown in FIGS. 2 and 3. In FIGS. 2, 3, and the other figures referred to below, the dimensions and number of parts may be exaggerated or simplified for ease of understanding. In addition, 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.

[0022] 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. Each component 2 to 6 is electrically connected to a control unit 9 that controls the entire apparatus, and operates in response to instructions from the control unit 9.

[0023] 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 to control each part of the substrate processing apparatus 1. As a result, the substrate processing apparatus 1 supplies a processing liquid to the peripheral portion 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 in detail later. In addition, in this embodiment, a control unit 9 is provided for each substrate processing apparatus 1, but a configuration may be adopted in which a single control unit controls multiple 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.

[0024] 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 disposed so that its upper surface is substantially horizontal and its central axis coincides with the rotation axis AX. A rotation shaft 22 is connected to the lower surface of the spin chuck 21. The rotation shaft 22 extends vertically with its axis coincident with the rotation axis AX. A rotation drive unit (e.g., a motor) 23 is also connected to the rotation shaft 22. The rotation drive unit 23 drives the rotation shaft 22 to rotate 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 22 around the rotation axis AX. The rotation drive unit 23 and the rotation shaft unit 22 function to rotate the spin chuck 21 around the rotation axis AX.

[0025] 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 22. A pump 24 ( FIG. 5 ) is connected to the internal space via a pipe having a valve (not shown). The pump 24 and the valve are electrically connected to the control unit 9 and operate in response 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 suction-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.

[0026] As shown in Fig. 3, the anti-scattering 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 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.

[0027] 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 when, for example, the substrate S is loaded onto or unloaded from the spin chuck 21.

[0028] 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 prevents 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 enables the processing liquid to be reliably recovered. 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, flow downward, and are collected and recovered by the liquid receiving portion 32 disposed below the cup 31.

[0029] The processing mechanism 4 has a base 41, a pivotal support shaft 42, an arm 43, and a processing liquid nozzle 44. The base 41 is fixed to the processing chamber 100. The pivotal support shaft 42 is rotatably mounted on the base 41. An arm 43 extends horizontally from the pivotal support shaft 42, and a processing liquid nozzle 44 is attached to its tip. The pivotal support shaft 42 rotates in response to a control command from the control unit 9, causing the arm 43 to swing. As a result, 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 edge 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.

[0030] 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 ejected 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 edge Ss of the substrate S moves. Therefore, as the spin chuck 21 rotates while the processing liquid nozzle 44 ejects the processing liquid, each portion of the peripheral edge Ss of the substrate S receives a supply of 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 edge Ss of the substrate S.

[0031] The peripheral edge heating mechanism 5 includes an annular heater 51. The heater 51 incorporates a heating element that extends in the circumferential direction of the substrate S along the peripheral edge of the lower surface 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 heat emitted from the heating element. This raises the temperature of the peripheral edge Ss to a value suitable for the bevel etching process.

[0032] The imaging mechanism 6 includes a base 6A, a pivotal support shaft 6B, an arm 6C, a head driver 6D, an illumination optical system 6E, an observation optical system 6F, and a head unit 6G. The base 6A is fixed to the processing chamber 100. The pivotal support shaft 6B is rotatably mounted on the base 6A. An arm 6C extends horizontally from the pivotal support 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 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 unit 6G attached to the tip of the arm 6C reciprocates between a retracted position P1, where the head driver 6D is retracted from above the substrate S to the side, and an imaging position P2, where the head driver 6D images the peripheral edge Ss of the substrate S. 3, the head unit 6G indicated by the solid line is in the retracted position, and the head unit 6G indicated by the dashed line is in the imaging position. At the imaging position P2, the head unit 6G is positioned close to the (-Y) side end of the substrate S.

[0033] As shown in FIG. 3 , the illumination optical system 6E and the observation optical system 6F are located at a distance P3, which is spaced from the imaging position P2 in the X direction. This distance P3 is spaced from the components (rotation mechanism 2, anti-scattering mechanism 3, processing mechanism 4, and peripheral heating mechanism 5) that perform the bevel etching process on the substrate S and the cup 31. The illumination optical system 6E irradiates illumination light L1 from outside the cup 31 toward the imaging position P2. At this time, the cup 31 is positioned in a downward position, and the head unit 6G is positioned at the imaging position P2, so that the illumination light L1 is incident on the head unit 6G. The illumination light L1 is diffusely reflected by the head unit 6G. The diffused light thus generated illuminates the peripheral edge Ss of the substrate S. The reflected light L2 reflected by the peripheral edge Ss of the substrate S is then further reflected by the head unit 6G. The reflected light L2 is guided from the head unit 6G toward the distance P3 and incident on the observation optical system 6F. As a result, the observation optical system 6 F acquires an image of the peripheral edge Ss of the substrate S, and sends the image data to the control unit 9 .

[0034] Here, the peripheral edge Ss of the substrate S, which is the image target 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 with an inclined surface formed on their peripheral edge. The "bevel portion" here refers to the entire area of ​​the peripheral edge Ss of the substrate S, where the surface is inclined with respect to the horizontal plane when the substrate S is in a horizontal position.

[0035] The cross-sectional shape and dimensions of the beveled portion are defined as standard specifications, with a maximum dimension Dmax shown by the dotted line and a 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 dimensions. In many cases, the cross section of the beveled portion is made up of multiple surfaces with different inclinations, as shown in Figure 4, but it can also be made up of a continuous curved surface.

[0036] 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. Furthermore, 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 term "periphery portion Ss" is a concept that comprehensively includes each of these surfaces.

[0037] As described above, the head unit 6G has both a diffuse illumination function of receiving illumination light L1 from the illumination optical system 6E, generating diffuse light, and illuminating the peripheral edge Ss of the substrate S with the diffused light, and a guide function of guiding reflected light L2 reflected by the peripheral edge Ss to the observation optical system 6F. The configuration and operation of the head unit 6G will be described below with reference to Figures 6A to 9. After that, the configuration and operation of the illumination optical system 6E will be described in detail.

[0038] 6A and 6B are perspective views showing the head unit of the imaging mechanism. More specifically, FIG. 6A shows the state in which head unit 6G is positioned at imaging position P2, and FIG. 6B shows the state in which substrate S has been removed from head unit 6G. Head unit 6G has a diffuse illumination unit 61 having a diffusion surface 610, a guide unit 62 composed of three mirror members 62a to 62c each surrounded by diffusion surface 610, and a holder 63 that holds diffuse illumination unit 61. In FIGS. 6A and 6B, a dot is added to the area corresponding to holder 63 to distinguish it from diffuse illumination unit 61.

[0039] The diffuse lighting unit 61 is made of a white fluorine-based resin, such as PTFE (polytetrafluoroethylene). The diffuse lighting unit 61 has a plate shape that is approximately parallel to the YZ plane, and has a notch 611 formed at the end on the (+Y) direction side. This notch 611 has a U-shape rotated 90 degrees clockwise when viewed from the (+X) direction side.

[0040] In the diffuse illumination unit 61, an inclined surface 610 is provided along the cutout portion 611. The inclined surface 610 is provided so as to surround the cutout portion 611 in the vertical direction 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 diffusion surface 610 that diffusely reflects the illumination light and causes it to be incident on the peripheral portion Ss of the substrate S.

[0041] Mirror members 62a to 62c are attached so as to be surrounded by diffusion surface 610. More specifically, on diffusion surface 610, first mirror member 62a is attached at a position vertically above notch 611, second mirror member 62b is attached on the (-Y) side of notch 611, and third mirror member 62c is attached at 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.

[0042] On the other hand, the holding unit 63 is made of a resin that is highly resistant to chemicals and heat, such as PEEK (polyetheretherketone), and is a plate-like member formed with an outline roughly equivalent to that of the diffuse illumination unit 61. The holding unit 63 is connected to the back surface of the diffuse illumination unit 61, i.e., the (-X) side principal surface, and functions as a backup member. The holding unit 63 is also connected to the arm 6C. Therefore, by swinging the arm 6C, the diffuse illumination unit 61 and the holding unit 63 move together between the retracted position P1 and the imaging position P2.

[0043] As shown in FIG. 6A , when the head unit 6G is at the imaging position P2 and the substrate S is held by the spin chuck 21, the peripheral edge Ss of the substrate S is positioned within the notch 611. When the notch 611 is viewed from the (+X) side toward the (-X) direction, the first mirror member 62a reflects the image of the portion of the substrate peripheral edge Ss that is visible when viewed from above, i.e., the A-side Sa and the B-side Sb. Similarly, the second mirror member 62b reflects the image of the portion of the substrate peripheral edge Ss that is visible when viewed from the side, i.e., the B-side Sb, the C-side Sc, and the D-side Sd. Furthermore, the third mirror member 62c reflects the image of the portion of the substrate peripheral edge Ss that is visible when viewed from below, i.e., the D-side Sd and the E-side Se.

[0044] As will be described in detail later, the observation optical system 6F captures images from the (+X) side in an imaging field of view that is set to view all three mirror members 62a to 62c. As a result, the images of the substrate S reflected by each of the mirror members 62a to 62c are captured in a single image. In other words, the observation optical system 6F can capture all of the surfaces A (Sa), B (Sb), C (Sc), D (Sd), and E (Se) of the substrate Ss in a single image. By capturing images multiple times as the substrate S rotates, it is possible to obtain images of multiple regions of the peripheral edge portion Ss that are positioned differently from one another along the circumferential direction.

[0045] In the following description, capturing images of the A-side Sa and B-side Sb of the substrate S reflected in the first mirror member 62a is referred to as "top surface capturing." Capturing images of the B-side Sb, C-side Sc, and D-side Sd of the substrate S reflected in the second mirror member 62b is referred to as "side surface capturing." Capturing images of the D-side Sd and E-side Se of the substrate S reflected in the third mirror member 62c is referred to as "bottom surface capturing."

[0046] 7A and 7B are diagrams schematically illustrating the progression of light that contributes to top-surface imaging. More specifically, FIG. 7A is a perspective view showing the path of light that is incident on and reflected by the head unit 6G, and FIG. 7B is a cross-sectional view taken along a vertical cut plane thereof. As indicated by solid arrows in FIGS. 7A and 7B, illumination light L1a of illumination light L1 traveling in the (-X) direction along the top surface of the substrate S is incident on the diffusing surface 610 of the head unit 6G. The light that is incident on the diffusing surface 610, particularly on the upper diffusing surface 61a located above the cutout portion 611, and diffused and reflected is incident on the top surface of the substrate S from various directions, thereby illuminating the substrate peripheral portion Ss.

[0047] In this embodiment, in order to satisfy the above-mentioned specular reflection suppression requirement, the head unit 6G and the illumination optical system 6E are arranged so that the angle of incidence of the illumination light L1a on the upper diffusion surface 61a is 54°. This also applies to the lower diffusion surface 61c and the side diffusion surface 61b, which will be described next. This specular reflection suppression requirement will be described in detail later.

[0048] As indicated by the dotted arrows, the light reflected by the substrate S can travel in various directions, but light L2a that is incident on the mirror member 62a and is reflected by the mirror member 62a and travels in the (+X) direction is incident on the observation optical system 6F arranged on the optical path. By receiving this light, "top surface imaging" is achieved, in which the peripheral edge portion Ss of the substrate S is imaged as viewed from the top surface side.

[0049] 7B , the same phenomenon as on the upper surface side occurs on the lower surface side of the substrate S. That is, the head unit 6G has a vertically symmetrical structure, and part of the illumination light L1, illumination light L1c traveling in the (−X) direction along the lower surface side of the substrate S, is incident on the diffusion surface 610, particularly on the lower diffusion surface 61c located below the notch 611, and is diffusely reflected, thereby illuminating the lower surface of the substrate S. At this time, reflected light L2c reflected by the substrate S and the mirror member 62c traveling in the (+X) direction is received, thereby achieving "lower surface imaging" that images the peripheral edge portion Ss as viewed from the lower surface side of the substrate S.

[0050] 8A and 8B are diagrams schematically illustrating the progression of light that contributes to side-side imaging. More specifically, FIG. 8A is a perspective view showing the path of light incident on and reflected from the head unit 6G, and FIG. 8B is a cross-sectional view of the same at a horizontal cut plane. As indicated by the solid arrows in FIGS. 8A and 8B, illumination light L1b of illumination light L1 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, particularly by the lateral diffusion surface 61b located to the side of the cutout portion 611. This light is incident on the side of the substrate S from various directions, thereby illuminating the substrate peripheral portion Ss.

[0051] Of the light reflected from the substrate S indicated by the dotted arrow, light L2b that is reflected by the mirror member 62b and travels in the (+X) direction is incident on the observation optical system 6F arranged on the optical path. This realizes "side surface imaging" that images the peripheral edge portion Ss of the substrate S as viewed from the side.

[0052] The observation optical system 6F includes an observation lens system composed of an object-side telecentric lens and, for example, a CMOS camera. Therefore, of the reflected light, only the reflected light L2 (L2a, L2b, L2c) parallel to the optical axis of the observation lens system is incident on the sensor surface of the CMOS camera, and an image of the peripheral edge Ss of the substrate S and the adjacent area is formed on the sensor surface. In this way, the observation optical system 6F captures an image of the peripheral edge Ss of the substrate S and the adjacent area, and acquires an image Im including, for example, a top surface image area Ma, a side surface image area Mb, and a bottom surface image area Mc, as shown in FIG. 9 . The observation optical system 6F then transmits image data representing the image to the control unit 9.

[0053] 9A and 9B are diagrams showing an image of the peripheral edge of a substrate captured by the imaging unit. Fig. 9A is a schematic diagram of the head unit 6G and the substrate S viewed from the (+X) side to the (-X) direction, and the area FV enclosed by the dashed line represents the imaging field of the observation optical system 6F. In this way, the imaging field of view FV of the observation optical system 6F is set to include the mirror members 62a to 62c of the head unit 6G.

[0054] 9(b) schematically shows images of the substrate S reflected on the mirror members 62a to 62c within the imaging field of view FV. As shown in FIG. 9(b), images of the A-side Sa and B-side Sb of the peripheral edge portion Ss of the substrate S are reflected on the first mirror member 62a. Images of the B-side Sb, C-side Sc, and D-side Sd of the peripheral edge portion Ss of the substrate S are reflected on the second mirror member 62b. Images of the D-side Sd and E-side Se of the peripheral edge portion Ss of the substrate S are reflected on the third mirror member 62c. The observation optical system 6F captures these images collectively to obtain a single image.

[0055] 9(c) is a schematic diagram of an image actually obtained by imaging. In the imaging mechanism 6 configured as described above, illumination light from the illumination optical system 6E is diffused by the diffusion surface 610 to illuminate the substrate S, and an image is captured by receiving a portion of the light reflected from the substrate S. As a result, 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, the sensitivity of the camera must be increased, and as a result, the detailed structure of the head unit 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 area Md corresponding to the cutout portion 611 and including an image of the side of the substrate S reflected out of focus within it, an upper surface image area Ma corresponding to the image of the peripheral portion Ss of the substrate S viewed from above, a side surface image area Mb corresponding to the image of the peripheral portion Ss of the substrate S viewed from the side, and a lower surface image area 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 edge of the substrate S in the circumferential direction, the etching status, 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 warpage 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 section of the apparatus to perform (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 an arithmetic processing section 91 that performs various types of arithmetic processing, a storage section 92 that stores basic programs and image data, and an input display section 93 that displays various types of information and receives input from the operator.

[0059] In the control unit 9, a calculation processor (CPU) 91 serving as a main control unit performs calculations in accordance with procedures written 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 positions 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 the 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 the 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 the 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 corrects the eccentricity of the substrate S with respect to the rotation axis AX by moving the substrate S by the above-mentioned amount of eccentricity. Since a conventionally known eccentricity correction mechanism can be used, a detailed description of the configuration of the eccentricity correction mechanism 7 will be omitted here.

[0061] The illumination optical system 6E of the imaging mechanism 6 irradiates the illumination light L1 as primary illumination light onto an area FV (see FIG. 9A) including the diffusion surface 610, thereby generating diffused light that is diffusely reflected by the diffusion surface 610 as secondary illumination light. The substrate S is then illuminated by this diffused light (illumination step). The observation optical system 6F of the imaging mechanism 6 receives a portion of the light reflected from the substrate S, thereby capturing an image of the peripheral portion Ss of the substrate S. In this manner, the peripheral portion Ss is observed by the observation optical system 6F (observation step). In this manner, the peripheral portion Ss of the substrate S is observed using the imaging mechanism 6; the substrate S and the peripheral portion Ss are examples of the "object under observation" and the "portion under observation," respectively, and the imaging mechanism 6 functions as the "observation device" of the present invention.

[0062] Here, it is necessary to satisfy both the p-polarized light observation requirement and the specular reflection suppression requirement in order to obtain a better image of the peripheral portion Ss using the imaging mechanism 6. The reason for this will be explained with reference to FIGS.

[0063] FIG. 10 is a schematic diagram illustrating the generation of specularly reflected light and diffused light when unpolarized primary illumination light is irradiated onto the diffuse illumination unit. FIG. 11 is a diagram illustrating an example of an image obtained by capturing an image of the peripheral portion of a substrate using unpolarized primary illumination light and p-polarized primary illumination light, respectively. Light L1 generated by an optical element such as an LED (light-emitting diode) is unpolarized (sometimes referred to as non-polarized). When this light is irradiated onto the diffuse illumination unit 61 as primary illumination light, specularly reflected light is generated on the surface (diffusing surface 610) of the diffuse illumination unit 61. Furthermore, light other than the specularly reflected light penetrates the interior of the diffuse illumination unit 61. The intruding light is then diffusely reflected by the PTFE that constitutes the diffuse illumination unit 61 and then exits as diffused light from the diffusing surface 610. Thus, the secondary illumination light emitted from the surface of the diffuse illumination unit 61 includes relatively high-intensity specularly reflected light (thick solid line in the figure) and diffused light that is close to Lambertian reflection (thin dotted line in the figure). The secondary illumination light has an extremely strong illuminance distribution only in the direction of the specularly reflected light. When the peripheral edge Ss of the substrate S was actually illuminated with unpolarized primary illumination light L1 and an image was taken, a side image region Mb was obtained in which a bright line BL was reflected, as shown in Figure 11(a) (Comparative Example). Therefore, when ray tracing of only the chief ray was performed, the position of the bright line BL matched the position within the side image region Mb. In other words, it was confirmed that the presence of specularly reflected light is the main cause of the bright line BL.

[0064] Therefore, as a method for suppressing specular reflection, we investigated the use of p-wave linearly polarized illumination and the incidence of primary illumination light L1 on the diffusing surface 610 of the diffuse illumination unit 61 at or near the Brewster angle. Because the refractive index of the PTFE constituting the diffuse illumination unit 61 is 1.35, the characteristics of specular reflection intensity for p-polarized and s-polarized light as a function of the incident angle θ (see FIG. 10 ) are shown in FIG. 12 . As is clear from FIG. 12 , the specular reflection intensity of p-polarized light becomes zero at 53.5°, i.e., the Brewster angle is 53.5°. In contrast, s-polarized light has high specular reflection intensity even when incident on the diffusing surface 610 of the diffuse illumination unit 61 at or near the Brewster angle. Therefore, even though the incident angle θ of illumination light L1 on the diffusing surface 610 is 54°, close to the Brewster angle, as described above, the bright line BL did not disappear as long as unpolarized primary illumination light L1 was used.

[0065] On the other hand, the characteristics of diffuse light intensity corresponding to the angle of incidence θ of p-polarized light are as shown in Figure 12. When observing with primary illumination light L1 that is only p-polarized, it has been confirmed that an image of the peripheral portion Ss can be obtained satisfactorily as long as the intensity of the p-polarized light specularly reflected by the diffuse illumination unit 61 is 10% or less of the intensity of the diffused light generated by the diffuse illumination unit. The lower and upper limit angles of the range in which the intensity of the p-polarized light specularly reflected by the diffuse illumination unit 61 is 10% or less of the intensity of the diffused light generated by the diffuse illumination unit (hereinafter referred to as the "specular reflection light suppression range") are 49° and 57°, respectively.

[0066] From these considerations, it can be said that satisfying the requirement that observation be performed using only p-polarized primary illumination light L1 (an example of a requirement for p-polarized observation) and the requirement that the angle of incidence of primary illumination light L1 be within the specular reflection suppression range is effective in suppressing the occurrence of bright lines BL. Therefore, in this embodiment, the illumination optical system 6E is configured as shown in Figure 12.

[0067] 13 shows an example of an illumination optical system installed in a substrate processing apparatus according to the present invention. Fig. 13(a) shows the overall configuration of the illumination optical system, and Fig. 13(b) shows a cross-sectional view of the illumination optical system 6E excluding the projection optical unit. The illumination optical system 6E includes a light source unit 64, an optical rod 65, a polarizer 66, and a projection optical unit 67. The light source unit 64, the optical rod 65, and the polarizer 66 are positioned and held by a light-emitting side housing 68. The light-emitting side housing 68 and the projection optical unit 67 are interconnected.

[0068] A through-hole 681 extends through the light-emitting side housing 68. A light source unit 64 and a polarizer 66 are attached to both ends of the light-emitting side housing 68 in the extension direction D1 of the through-hole 681 (the left-right direction on the plane of FIG. 13 ). An optical rod 65 is disposed inside the through-hole 681 parallel to the extension direction D1 and is fixed by a rod holder (not shown). The optical rod 65 is made of glass or a resin material that is transparent to the light beam emitted from the light source unit 64, and has a columnar shape that extends in a direction parallel to the extension direction D1.

[0069] 13C, the light source unit 64 has one or more light-emitting elements 641 and a light source substrate 642 on which the light-emitting elements 641 are mounted. In this embodiment, four light-emitting elements 641 are arranged in a matrix.

[0070] FIG. 14 is a diagram showing an example of a drive circuit for light-emitting elements. As shown in the figure, four light-emitting elements 641 are connected in series to a DC power supply. A semiconductor relay 643 is provided for each light-emitting element 641, and controls the illumination of the corresponding light-emitting element 641 in response to signals OUT1 to OUT4 from the control unit 9. When the light-emitting elements 641 are identical, the illumination control can adjust the intensity of the light beam emitted from the light source unit 64. When the four light-emitting elements 641 emit light beams of different wavelengths, the illumination control can adjust the intensity and color of the light beam emitted from the light source unit 64. In this embodiment, LEDs are used as the light-emitting elements 641, and unpolarized light is emitted.

[0071] Returning to FIG. 13 , the explanation continues. In order to efficiently dissipate heat generated when the light-emitting element 641 is turned on, an aluminum heat dissipation member 644 is attached to the side of the light source substrate 642 opposite the light-emitting element (the left-hand side in the figure), as shown in FIGS. 13A and 13B . In this embodiment, the light-emitting element 641, the light source substrate 642, and the heat dissipation member 644 are integrated to form a light-emitting structure 69. Furthermore, the light-emitting structure 69 is detachable from the light-emitting side housing 68. For example, the light-emitting element 641 may be replaced with a new light-emitting structure 69 according to the lifespan of the light-emitting element 641. Alternatively, light-emitting structures 69 having different combinations of light-emitting elements 641 in terms of light emission color, number, etc. may be prepared in advance, and the light-emitting structure 69 may be selectively attached according to the type of substrate S to be processed.

[0072] 13(c), a protective cover 645 is provided on the light-emitting element side of the light source substrate 642 so as to cover the light-emitting element 641. The protective cover 645 is made of glass or a resin material that is transparent to the light beam emitted from the light-emitting element 641, and its end face 645a on the optical rod side is finished to a flat surface. This end face 645a faces and is in close contact with the end face of the optical rod 65. Therefore, when the light-emitting element 641 is turned on and emits a light beam, the light beam emitted from the light-emitting element 641 with a certain spread enters the optical rod 65 through the protective cover 645.

[0073] The cross section of the optical rod 65 has a circular or polygonal shape, with the end face on the light source side (left-hand side in the figure) corresponding to the incident end and the end face on the projection optical side (right-hand side in the figure) corresponding to the exit end. That is, in the optical rod 65, when the light beams emitted from the light source 64 enter the end face on the light source side, most of the light beams, except for a portion of the light beams, are totally reflected inside the optical rod 65 and propagate in the extension direction D1. Then, light beams with substantially identical characteristics are emitted from each portion of the end face on the projection optical side. Therefore, the light intensity distribution of the light beams at the end face has a top-hat shape.

[0074] Here, by configuring the projection optical unit 67 to magnify the exit end of the optical rod 65 by an appropriate magnification and project it onto the diffusion surface 610, it is possible to provide primary illumination to the diffusion surface 610 with a uniform light intensity distribution. However, if the unpolarized light emitted from the optical rod 65 is directly irradiated onto the diffusion surface 610 as the primary illumination light L1, the p-polarized light observation requirements are not met, and bright lines BL are generated for the reasons described above. Therefore, in this embodiment, a polarizer 66 that transmits only p-polarized light is disposed between the optical rod 65 and the projection optical unit 67. Therefore, the primary illumination light L1 is composed of only p-polarized light that is irradiated onto the diffusion surface 610 via the polarizer 66 and the projection optical unit 67. In other words, the illumination optical system 6E includes a light source unit 64 that emits unpolarized light and a polarizer 66 (corresponding to an example of the "first polarizer" in the present invention) that transmits only p-polarized light from the unpolarized light emitted from the light source unit 64, and irradiates the p-polarized light emitted from the polarizer 66 as the primary illumination light L1. This corresponds to the "first condition" of the present invention, and in this embodiment, the p-polarized light observation requirement is satisfied. Furthermore, the angle of incidence of the illumination light L1 on the diffusing surface 610 is 54°, suppressing specular reflection to nearly zero, thereby satisfying the specular reflection suppression requirement. This suppresses the inclusion of specular reflection in the secondary illumination light, and as shown in FIG. 11(b), it is possible to suppress the inclusion of the bright line BL in the side image region Mb. As a result, the above-mentioned problem is resolved, and the peripheral portion Ss of the substrate S can be observed with excellent quality. The polarizer 66 may be positioned anywhere in the illumination optical system 6E; for example, it may be positioned between the light source unit 64 and the optical rod 65.

[0075] The basic configuration of the first embodiment is summarized in the "First embodiment" column in Table 1.

[0076] In Table 1, blank spaces indicate that the basic configuration is not included in each embodiment.

[0077] In the first embodiment, the p-polarized light observation requirement is satisfied by generating p-polarized primary illumination light L1 using the polarizer 66 in the illumination optical system 6E. However, other configurations may be used to satisfy the p-polarized light observation requirement. For example, as shown in the "Second Embodiment" column in Table 1, instead of the polarizer 66, a polarizer that passes only p-polarized light (equivalent to an example of the "second polarizer" of the present invention) may be provided in the observation optical system 6F, and only p-polarized reflected light L2 may be received. In other words, in the second embodiment, the "second condition" of the present invention is satisfied, thereby satisfying the p-polarized light observation requirement. Furthermore, the incident angle θ is set to 54°, as in the first embodiment, and the specular reflection suppression requirement is satisfied. Therefore, the same effects as those of the first embodiment can be obtained.

[0078] Alternatively, the light source unit 64 may be configured with an LD (semiconductor laser). When the light emitted from the LD is p-polarized, the p-polarized light can be used as the primary illumination light L1 (third embodiment). On the other hand, when the light emitted from the LD is s-polarized, a rotator can be added to the light source unit 64 to rotate the s-polarized light by 90 degrees, and the p-polarized light emitted from the rotator can be used as the primary illumination light L1 (fourth embodiment). As described above, the light emitted from the light source unit 64 is p-polarized and is used as the primary illumination light L1. In other words, in the third and fourth embodiments, the "third condition" of the present invention is satisfied, thereby satisfying the p-polarized light observation requirement. Furthermore, the incident angle θ is set to 54°, as in the first embodiment, and the specular reflection suppression requirement is satisfied. Therefore, the same effects as those of the first embodiment can be obtained.

[0079] The present invention is not limited to the above-described embodiment, and various modifications other than those described above are possible without departing from the spirit of the present invention. For example, in the embodiment, four light-emitting elements 641 are used, but the number of light-emitting elements 641 is not limited to four and can be any number. For example, a light beam may be emitted from a single light-emitting element having a relatively wide light-emitting surface. Of course, a light beam may also be emitted from two, three, five or more light-emitting elements 641.

[0080] In the above embodiment, the head unit 6G and the illumination optical system 6E are arranged so that the incident angle θ is 54°, but the incident angle θ may be set to the Brewster angle. Furthermore, the head unit 6G and the illumination optical system 6E may be arranged so that the incident angle θ is within the range of 49° to 57°, other than the above angles.

[0081] In the above embodiment, the optical rod 65 is used as a "beam homogenizer" for homogenizing the amount of light emitted from the light source unit 64, but other beam homogenizers may also be used.

[0082] In the embodiment, the lengths of the upper diffusion surface 61a, the lower diffusion surface 61c, and the mirror members 62a and 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 depending on the range to be observed by the imaging mechanism 6. Furthermore, head units 6G having different Y-direction lengths of the diffusion surface and mirror member may be prepared, and a head unit 6G may be selectively used depending on the imaging range. Furthermore, when head units 6G having different Y-direction lengths of the diffusion surface are prepared, the diffusion surface of the head unit 6G may be composed of a continuous curved surface. Furthermore, when head units 6G having different Y-direction lengths of the diffusion surface are prepared, a portion of the diffusion surface of the head unit 6G may be composed of a flat surface.

[0083] In the above embodiment, the observation lens system of the observation optical system 6F is configured with an object-side telecentric lens, but the configuration of the observation lens system of the observation optical system 6F is not limited to this. The observation lens system of the observation optical system 6F may be configured with other lenses.

[0084] Furthermore, in the above embodiment, the reflected light L2 reflected at the peripheral portion Ss of the substrate S is configured to be received by the observation optical system 6F via the mirror members 62a to 62c, but the reflected light L2 may also be configured to be received by the observation optical system 6F.

[0085] In the above embodiment, the diffuse illumination unit 61 and the holding unit 63 are made of chemical-resistant and heat-resistant materials because they are exposed to the environment of the processing liquid used in the bevel etching process and the heating environment of the heater 51. While the diffuse illumination unit 61 and the holding unit 63 are made of PTFE and PEEK, respectively, their materials are not limited to these. The diffuse illumination unit 61 may be made of a chemical-resistant and heat-resistant material other than PTFE. The holding unit 63 may be made of a chemical-resistant and heat-resistant material other than PEEK. The diffuse illumination unit 61 and the holding unit 63 may be made of, for example, a metal, resin, or ceramic material whose surface is coated with a fluororesin material such as PFA. Although the diffuse illumination unit 61 and the holding unit 63 are made of different materials, they may also be made of the same material. Furthermore, the materials of the diffuse illumination unit 61 and the holding unit 63 are not limited when they are used in an environment that does not require chemical resistance and heat resistance. The diffuse illumination unit 61 and the holder 63 may be made of a material that is not chemically or heat resistant.

[0086] Furthermore, there are no limitations on the configuration of the diffusing surfaces 61a to 61c of the diffuse illumination unit 61 and the holding unit 63. For example, when at least a part of the diffuse illumination unit 61 or the holding unit 63 is made of a metal material, the diffusing surfaces 61a to 61c may be made of a metal material whose surface has been subjected to shot blasting.

[0087] In the above embodiment, the diffuse illumination unit 61 is made of PTFE, but the material is not limited to this. The diffuse illumination unit 61 may be made of, for example, polyoxymethylene (e.g., Delrin (trademark)), ultra-high molecular weight polyethylene (UHMW-PE), polyethylene (PE), polyvinyl chloride (PVC), polypropylene (PP), or the like.

[0088] 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 are chemically resistant to the processing solution and heat resistant to the processing temperature. The mirror members 62a to 62c may be configured, for example, by vapor-depositing a metal material on the surface of a chemically and heat-resistant material. Furthermore, when the mirror members 62a to 62c are used in an environment where chemical and heat resistance are not required, the constituent material is not limited. The mirror members 62a to 62c may be configured, for example, by vapor-depositing a metal material on the surface of a material that is not chemically and heat-resistant.

[0089] Furthermore, in the above embodiment, the imaging mechanism 6 is fixed, while the peripheral portion of the substrate S, which is the object under observation, is imaged by moving it, but the imaging mechanism 6 may be configured to move while the substrate S is fixed. Also, both the substrate S and the imaging mechanism 6 may be moved. That is, the peripheral portion of the object under observation (substrate S) may be imaged by the observation device while the object under observation (substrate S) is moved relative to the observation device (imaging mechanism 6).

[0090] Furthermore, in the above embodiment, the imaging mechanism 6 corresponding to the observation device according to the present invention is incorporated into the substrate processing apparatus 1 that performs bevel etching on the peripheral portion Ss of the substrate S, but the application of the observation device (imaging mechanism 6) is not limited to this. The present invention can also be applied to an observation device that images an observation portion of an object under observation. Furthermore, the imaging mechanism 6 corresponding to the observation device according to the present invention can also be applied to a substrate processing apparatus that supplies a coating film remover to the peripheral portion of the substrate S on which a coating film has been formed, thereby removing the coating film from the peripheral portion of the substrate S. It can also be applied to an observation device that observes the surface of a substrate before performing an exposure process.

[0091] While the invention has been described with reference to specific embodiments, this description is not intended to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as other embodiments of the invention, will become apparent to those skilled in the art upon reference to the description of the invention. It is therefore contemplated that the appended claims will cover such modifications or embodiments within the true scope of the invention.

[0092] The present invention can be applied to observation techniques for observing objects to be observed, such as semiconductor wafers, as well as to substrate processing apparatuses that utilize such observation techniques.

[0093] DESCRIPTION OF SYMBOLS 1...Substrate processing apparatus 2...Rotation mechanism 4...Processing mechanism 6...Imaging mechanism (observation device) 6E...Illumination optical system 6F...Observation optical system 6G...Head section 61...Diffused illumination section 61a to 61c, 610...Diffused surface 64...Light source section 641...Light emitting element 610...Inclined surface 611...Notch section L1, L1a to L1c...Primary illumination light L2, L2a to L2c...Reflected light P2...Imaging position S...Substrate Ss...Periphery (of substrate)

Claims

1. An observation device for observing an observed portion of an object under observation, comprising: an illumination optical system which irradiates a vicinity of the observed portion with primary illumination light; a head unit which has a diffusion illumination unit which diffuses the primary illumination light in the vicinity of the observed portion and which irradiates and illuminates the observed portion with diffused light generated by the diffusion illumination unit as secondary illumination light; and an observation optical system which receives light reflected from the observed portion illuminated with the secondary illumination light and observes the observed portion, wherein a first condition is that the illumination optical system has a light source unit which emits unpolarized light and a first polarizer which transmits only p-polarized light of the unpolarized light emitted from the light source unit, and the p-polarized light emitted from the first polarizer is irradiated as the primary illumination light; and a second condition is that the illumination optical system has a light source unit which emits unpolarized light as the primary illumination light, and the observation optical system has a second polarizer which transmits only p-polarized light of the light reflected from the observed portion, and the p-polarized light emitted from the second polarizer is received as the reflected light, An observation device characterized in that, when the third condition is that the illumination optical system has a light source unit that emits p-polarized light as the primary illumination light, one of the first condition to the third condition is satisfied, and the illumination optical system is positioned with respect to the head unit so that the angle of incidence of the primary illumination light on the diffuse illumination unit is within a range from a lower limit angle smaller than Brewster's angle to an upper limit angle larger than Brewster's angle, such that the intensity of the p-polarized light specularly reflected by the diffuse illumination unit is 10% or less of the intensity of the diffuse light generated by the diffuse illumination unit.

2. An observation device according to claim 1, wherein the diffusing illumination section is made of a fluorine-based resin.

3. An observation device according to claim 2, wherein the fluororesin is polytetrafluoroethylene, and the lower limit angle and the upper limit angle are 49° and 57°, respectively.

4. An observation method for observing an observed portion of an object under observation, comprising: an illumination step of irradiating a diffuse illumination unit of a head unit positioned near the observed portion with primary illumination light from an illumination optical system, thereby irradiating and illuminating the observed portion with diffuse light generated by the diffuse illumination unit as secondary illumination light; and an observation step of receiving light reflected by the observed portion illuminated by the secondary illumination light to observe the observed portion, wherein the illumination step is performed in a state in which the intensity of the p-polarized light specularly reflected by the diffuse illumination unit is 10% or less of the intensity of the diffuse light generated by the diffuse illumination unit by positioning the illumination optical system with respect to the head unit so that the angle of incidence of the primary illumination light on the diffuse illumination unit is within a range from a lower limit angle smaller than Brewster's angle to an upper limit angle larger than Brewster's angle, The observation method is characterized in that the observation step is a step of receiving the light reflected from the observed area as the reflected light as it is when only p-polarized light is irradiated as the primary illumination light in the illumination step, and extracting only p-polarized light from the light reflected from the observed area and receiving it as the reflected light when unpolarized light is irradiated as the primary illumination light in the illumination step.

5. A method for manufacturing a substrate-processing system comprising: a rotation mechanism for holding and rotating a substrate; a processing mechanism for supplying a processing liquid to a peripheral portion of the substrate rotated by the rotation mechanism to process the peripheral portion of the substrate; and an observation device for observing the peripheral portion before or after processing the peripheral portion, wherein the observation device comprises: an illumination optical system for irradiating a vicinity of the peripheral portion with primary illumination light; a head unit having a diffusion illumination unit for diffusing the primary illumination light in the vicinity of the peripheral portion, and irradiating and illuminating the peripheral portion with diffused light generated by the diffusion illumination unit as secondary illumination light; and an observation optical system for receiving light reflected by the peripheral portion illuminated by the secondary illumination light to observe the peripheral portion, wherein a first condition is that the illumination optical system has a light source unit for emitting unpolarized light and a first polarizer for transmitting only p-polarized light of the unpolarized light emitted from the light source unit, and the p-polarized light emitted from the first polarizer is irradiated as the primary illumination light, a first polarizer that transmits only p-polarized light from the light reflected by the peripheral portion and receives the p-polarized light emitted from the second polarizer as the reflected light; and a third condition that the illumination optical system has a light source that emits p-polarized light as the primary illumination light. When the second condition is that the illumination optical system has a light source that emits p-polarized light as the primary illumination light, and the third condition is that the illumination optical system has a light source that emits p-polarized light as the primary illumination light, one of the first condition to the third condition is satisfied, and the illumination optical system is positioned with respect to the head unit so that the angle of incidence of the primary illumination light on the diffuse illumination unit is within a range from a lower limit angle smaller than Brewster's angle to an upper limit angle larger than Brewster's angle, the intensity of the p-polarized light specularly reflected by the diffuse illumination unit is 10% or less of the intensity of the diffuse light generated by the diffuse illumination unit.

Images