Observation device and substrate treatment device

Abstract

The present invention pertains to: an observation device for observing an observation part to be observed in an observation target object; and a substrate treatment device comprising the observation device. In this observation device, primary illumination light is diffused by a diffusion illumination unit of a head part that is disposed in the vicinity of an observation part to be observed, to generate secondary illumination light. The observation part to be observed is illuminated by the secondary illumination light, and the observation part is observed through reception of reflected light obtained from reflection on the observation part to be observed. In particular, the diffusion illumination unit has an equally diffusing reflection surface having characteristics approximating those of Lambertian reflection, and generates the secondary illumination light through diffusion by the equally diffusing reflection surface. As a result, observation parts to be observed such as a peripheral edge portion of a semiconductor wafer can be satisfactorily imaged.

Description

Observation device and substrate processing device

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

[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. 2023-152744 (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 device that can satisfactorily observe an observation portion such as the peripheral portion of a semiconductor wafer, and a substrate processing apparatus equipped with the observation device.

[0008] A first aspect of the present invention is an observation device for observing an observation portion of an object under observation, characterized in that it comprises an illumination optical system that irradiates primary illumination light onto the vicinity of the observation portion, a diffusion illumination unit that diffuses the primary illumination light near the observation portion using an equal-diffuse reflecting surface having characteristics approximating Lambertian reflection, a head unit that irradiates and illuminates the observation portion with the diffused light generated by the equal-diffuse reflecting surface as secondary illumination light, and an observation optical system that receives light reflected by the observation portion illuminated by the secondary illumination light and observes the observation portion.

[0009] In addition, a second 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 is characterized by comprising: an illumination optical system that irradiates primary illumination light near the peripheral edge; a diffusion illumination unit that diffuses the primary illumination light near the peripheral edge using an equal-diffuse reflecting surface having characteristics similar to Lambertian reflection, and a head unit that irradiates and illuminates the peripheral edge with the diffused light generated by the equal-diffuse reflecting surface as secondary illumination light; and an observation optical system that receives reflected light reflected from the peripheral edge illuminated by the secondary illumination light to observe the peripheral edge.

[0010] In these inventions, a 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. The diffuse illumination unit has a uniform diffuse reflecting surface with characteristics similar to Lambertian reflection, and diffuses the primary illumination light. Therefore, as will be described later with reference to FIG. 10 , the brightness of the specular reflection light contained in the secondary illumination light is suppressed, improving the quality of the observation image.

[0011] 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.

[0012] 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.

[0013] 4 is a diagram showing a substrate processing system equipped with an embodiment of a substrate processing apparatus according to the present invention. FIG. 4 is a diagram showing a schematic configuration of a substrate processing apparatus. FIG. 4 is a plan view of a part of the substrate processing apparatus seen from above. FIG. 4 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. 4 is a perspective view showing a head unit of an imaging mechanism. FIG. 4 is a perspective view showing a head unit of an imaging mechanism. FIG. 4 is a diagram showing a schematic view of the progression of light that contributes to top surface imaging. FIG. 4 is a diagram showing a schematic view of the progression of light that contributes to side surface imaging. FIG. 4 is a diagram showing a schematic view of the progression of light that contributes to side surface imaging. FIG. 4 is a diagram showing a schematic view of an image of the peripheral portion of a substrate imaged by an imaging unit. FIG. 4 is a diagram showing a schematic view of the generation of specularly reflected light and diffused light when primary illumination light is irradiated onto a diffuse illumination unit. FIG. 4 is a diagram showing an example of an image obtained by imaging the peripheral portion of a substrate.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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 .

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] The diffuse illumination unit 61 is made of a white fluorine-based resin, such as PTFE (polytetrafluoroethylene). More specifically, the diffuse illumination unit 61 is made of a porous resin formed by sintering granular PTFE. An example of such a resin material is Spectralon manufactured by Labsphere. In this embodiment, the diffuse illumination unit 61 is processed as follows to have a shape suitable for substrate observation. Specifically, the diffuse illumination unit 61 has a plate shape approximately parallel to the YZ plane, with a notch 611 formed at the end on the (+Y) side. This notch 611 has a U-shape rotated 90 degrees clockwise when viewed from the (+X) side. Using the diffuse illumination unit 61 configured in this manner achieves a specular reflection suppression effect. This point will be described in detail later.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] As will be described in detail later, the observation optical system 6F captures images in an imaging field of view that is set so as to view all three mirror members 62a to 62c from the (+X) side. As a result, the images of the substrate S reflected on 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 A-side Sa, B-side Sb, C-side Sc, D-side Sd, and E-side 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.

[0042] 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."

[0043] 7A and 7B are schematic diagrams illustrating the progression of light that contributes to top-surface imaging. More specifically, FIG. 7A is a perspective view showing the path of light incident on and reflected from the head unit 6G, and FIG. 7B is a cross-sectional view taken along a vertical cut plane thereof. As indicated by the 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 diffusion surface 610 of the head unit 6G. The illumination light L1a is incident on the diffusion surface 610, particularly on the upper diffusion surface 61a located above the notch 611, and is diffusely reflected with characteristics similar to Lambertian reflection. This diffusely reflected light then strikes the top surface of the substrate S from various directions, illuminating the substrate peripheral edge Ss. In this embodiment, the head unit 6G and illumination optical system 6E are positioned so that the angle of incidence of illumination light L1a on the upper diffusion surface 61a is 54°. This also applies to the downward diffusion surface 61c and the side diffusion surface 61b, which will be described next.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] In the control unit 9, a calculation processor (CPU) 91 serving as a main control unit performs calculations in accordance with procedures described in a program, thereby controlling each part of the substrate processing apparatus 1 as follows: That is, as shown in Fig. 5, the calculation processor 91 functions as a positioning control unit 911 that 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.

[0056] 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.

[0057] The illumination optical system 6E of the imaging mechanism 6 irradiates an area FV (see FIG. 9( a)) including the diffusion surface 610 with illumination light L1 as primary illumination light, 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. The observation optical system 6F of the imaging mechanism 6 receives a portion of the light reflected from the substrate S, thereby imaging the peripheral portion Ss of the substrate S. In this manner, the peripheral portion Ss is observed by the observation optical system 6F. 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 correspond to examples of the "object under observation" and the "portion under observation" of the present invention, respectively, and the imaging mechanism 6 functions as the "observation device" of the present invention.

[0058] Here, in order to obtain a better image of the peripheral portion Ss by the imaging mechanism 6, it is important to suppress the brightness of the specularly reflected light contained in the secondary illumination light, that is, to exert the specular reflection suppression effect. The reason for this will be explained with reference to FIGS. 10 and 11.

[0059] FIG. 10 is a diagram schematically illustrating the generation of specularly reflected light and diffused light when primary illumination light is irradiated onto the diffuse illumination unit. (a) shows the generation of specularly reflected light and diffused light in a conventional example in which the diffuse illumination unit 61 is constructed using a conventionally used diffuse-reflecting material (e.g., PTFE with a uniform surface obtained by machining), while (b) shows the generation of specularly reflected light and diffused light in this embodiment in which the diffuse illumination unit 61 is constructed using a diffuse-reflecting material (Spectralon). FIG. 11 is also a diagram illustrating an example of an image obtained by capturing an image of the peripheral portion of a substrate. (a) shows the image in the conventional example, and (b) shows the image in this embodiment. In the conventional example, when light L1 generated by an optical element such as an LED (light-emitting diode) is irradiated onto the diffuse illumination unit 61 as primary illumination light, specularly reflected light is generated on the surface (diffusion surface 610) of the diffuse illumination unit 61 and is also surface-scattered by the diffusion surface 610. Furthermore, light that penetrates the interior of the diffuse illumination unit 61 is diffusely reflected by the PTFE that constitutes the diffuse illumination unit 61 and then exits as diffuse light from the diffusion surface 610. Thus, as shown in FIG. 10( a), 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 diffuse light 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 the 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 FIG. 11( a), for example. Therefore, ray tracing of only the chief ray was performed, and the results showed that 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.

[0060] In contrast, in this embodiment, as described above, the diffusing surface 610 is finished to be relatively rough so that its surface roughness is 2 μm or more and 10 μm or less. Therefore, the primary illumination light L1 incident on the diffusing surface 610 and the light scattered inside the diffused illumination unit 61 are surface-scattered by the diffusing surface 610. The definition of "surface roughness" here is the arithmetic mean roughness (Ra).

[0061] The diffuse illumination unit 61 is made of a porous resin formed by sintering granular PTFE, and has a microstructure with voids inside. Therefore, the primary illumination light L1 that enters the diffuse illumination unit 61 through the diffusion surface 610 is scattered inside the diffuse illumination unit 61 and then exits from the diffusion surface 610.

[0062] Furthermore, in this embodiment, Spectralon is used as the diffuse illumination unit 61, which has a relatively high transmittance to the primary illumination light L1. Moreover, the diffuse illumination unit 61 is made of a crystalline resin, and the illumination light L1 is scattered at the boundaries of its crystalline structure.

[0063] As described above, in this embodiment, (a) surface scattering, (b) internal scattering due to the presence of voids, and (c) internal scattering due to the crystalline structure all occur. Therefore, the diffusing surface 610 is a uniform diffuse reflecting surface with characteristics similar to Lambertian reflection. As shown in FIG. 10( b), the brightness of the specularly reflected light in the secondary illumination light emitted from the diffusing surface 610 is reduced (specular reflection suppression effect), while the brightness of the diffusely reflected light is increased. In other words, the secondary illumination light emitted from the diffusing surface 610 is diffusely reflected light similar to Lambertian reflection. Therefore, the inclusion of specularly reflected light in the secondary illumination light is suppressed, and as shown in FIG. 11( b), the inclusion of the bright line BL in the side image region Mb can be suppressed. As a result, the above-mentioned problems can be resolved while the peripheral portion Ss of the substrate S can be observed with excellent quality.

[0064] 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, the diffuse illumination unit 61 that generates all three types of scattering (a) to (c) is used, but a diffuse illumination unit 61 configured to generate at least one of these types of scattering may also be used. More specifically, the diffuse illumination unit 61 may be configured as follows.

[0065] Polyoxymethylene (e.g., Delrin (trademark)) is a crystalline resin similar to Spectralon, and its powder may be sintered and molded. The diffused illumination unit 61 thus manufactured has the same effects as one made of Spectralon.

[0066] Alternatively, the diffuse illumination portion 61 may be manufactured by uniformly dispersing barium sulfate particles, which function as a scattering material, inside a resin material.

[0067] In the above embodiment, the diffuse illumination unit 61 is made of a sintered powder of a resin material, but the diffuse illumination unit 61 may be made by, for example, subjecting the surface of PTFE to a blasting treatment. In this case, the surface that has been subjected to the blasting treatment corresponds to the diffusing surface 610 of the diffuse illumination unit 61, and surface scattering occurs on the diffusing surface 610.

[0068] In addition, in the above embodiment, PTFE and polyoxymethylene are exemplified as the resin material, but other resin materials are also included, such as ultra-high molecular weight polyethylene (UHMW-PE), polyethylene (PE), polyvinyl chloride (PVC), and polypropylene (PP).

[0069] In addition, the entire diffused lighting section 61 is made of a resin material such as PTFE, but it may also be configured so that a base material such as a metal material or a ceramic material is covered with a coating layer made of the above-mentioned resin material (including one that disperses scattering substances), and the surface of the coating layer functions as the diffused surface 610.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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).

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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 (uniform diffuse reflection surface) 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 diffusion illumination unit which diffuses the primary illumination light in the vicinity of the observed portion using an even-diffuse reflecting surface having characteristics approximating Lambertian reflection, a head unit which irradiates and illuminates the observed portion with the diffuse light generated by the even-diffuse reflecting surface as secondary illumination light; and an observation optical system which receives light reflected by the observed portion illuminated by the secondary illumination light and observes the observed portion.

2. An observation device as claimed in claim 1, wherein the entire diffuse illumination section is formed from resin or resin containing dispersed scattering material that scatters light incident thereon.

3. An observation device according to claim 1, wherein the diffuse illumination section has a base material and a coating layer coated on the base material, at least a portion of the surface of which is finished to be the uniform diffuse reflecting surface.

4. An observation device according to claim 3, wherein the entire coating layer is formed from resin or resin having dispersed therein a scattering material that scatters light incident thereon.

5. An observation device according to claim 2 or 4, wherein the resin is polytetrafluoroethylene or polyoxymethylene.

6. An observation device according to claim 5, wherein the resin is a porous resin formed by sintering granular polytetrafluoroethylene or granular polyoxymethylene.

7. An observation device according to claim 2 or 4, wherein the scattering material is barium sulfate.

8. An observation device according to any one of claims 1 to 4, wherein the surface roughness of the uniform diffuse reflection surface is in the range of 2 μm to 10 μm in arithmetic mean roughness (Ra).

9. A substrate processing apparatus 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, wherein the observation device comprises: an illumination optical system for irradiating a vicinity of the peripheral portion with primary illumination light; a diffusion illumination unit for diffusing the primary illumination light in the vicinity of the peripheral portion using an even-diffuse reflecting surface having characteristics approximating Lambertian reflection, a head unit for irradiating and illuminating the peripheral portion with the diffused light generated by the even-diffuse reflecting surface as secondary illumination light; and an observation optical system for receiving light reflected from the peripheral portion illuminated by the secondary illumination light to observe the peripheral portion.

Images