Inspection apparatus, inspection method, and wafer manufacturing method

Abstract

To provide an inspection device capable of easily specifying the direction of a workpiece in which a plurality of inclined parts are included in a first surface.SOLUTION: The inspection device includes a target, a camera for performing imaging by using light emitted from the target and transmitted through a workpiece or reflected on a first surface of the workpiece after being reflected on a surface of the target or passing around the target without being shielded by the target, and a controller for controlling the camera. The controller includes a memory configured to store data indicating a relationship between a position of the target in an image formed by imaging using the light and the second direction and / or the third direction, and a processor configured to control the camera to form a specification image by imaging using the light, and then specify the second direction and the third direction with reference to the data and the position of the target in the specification image.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an inspection device for inspecting a workpiece having a first surface and a second surface located opposite the first surface and perpendicular to the first direction, the first surface including a plurality of inclined portions that extend along a second direction perpendicular to the first direction and are periodically arranged in a third direction perpendicular to both the first and second directions; an inspection method for inspecting the workpiece; and a wafer manufacturing method for manufacturing a wafer having a first surface and a second surface located opposite the first surface and perpendicular to the first direction, the first surface including a plurality of inclined portions that extend along the second direction perpendicular to the first direction and are periodically arranged in the third direction perpendicular to both the first and second directions, from an ingot having a second surface and a third surface located opposite the second surface and parallel to the second surface. [Background technology]

[0002] Semiconductor device chips are manufactured using wafers with a disk-like shape made of a single crystal material such as silicon carbide (SiC). These wafers are manufactured from ingots using a laser beam with a wavelength that is transparent to the material (e.g., SiC) (see, for example, Patent Document 1).

[0003] When manufacturing wafers in this way, first, the ingot and the focal point where the laser beam is focused are moved relative to each other while irradiating the ingot with a laser beam so that the focal point is positioned at a predetermined target depth from the surface of the ingot. As a result, a peeling layer containing a portion where the crystal structure of the ingot material is disrupted (modified portion) and cracks extending from the modified portion is formed inside the ingot.

[0004] Once a delamination layer is formed inside the ingot, an external force is applied to the ingot to further extend the cracks in the delamination layer, resulting in the ingot being split at the delamination layer (i.e., the portion of the ingot near the surface is delaminate) and wafers being produced.

[0005] When wafers are manufactured in this manner, periodic slopes may be formed on the first surfaces of the wafers and the remaining ingots (specifically, on the surfaces newly exposed by dividing the original ingot). For example, ingots made from single-crystal SiC are generally manufactured by epitaxial growth on a substrate made of single-crystal SiC. During this epitaxial growth, the c-axis of the SiC is often slightly tilted with respect to the normal to the surface of the substrate to reduce lattice defects formed inside.

[0006] Furthermore, when an ingot manufactured in this manner is irradiated with a laser beam as described above, cracks tend to propagate along the c-plane of SiC. Therefore, when wafers are manufactured from this ingot as described above, the first surfaces of the wafers and ingots often contain multiple inclined portions that are inclined along the c-plane and aligned in a predetermined direction. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-127186 Summary of the Invention [Problem to be solved by the invention]

[0008] When handling a wafer or ingot (hereinafter also referred to as "workpiece") having a first surface including a plurality of inclined portions, it may be necessary to identify the orientation of the workpiece (specifically, the direction in which each inclined portion extends and the direction in which the plurality of inclined portions are arranged). For example, when processing a workpiece on which a mark (e.g., a notch or orientation) is formed in the direction in which each inclined portion extends from the center to facilitate understanding of the crystal orientation of the material of the workpiece, it may be necessary to hold the workpiece with this direction aligned with a predetermined direction.

[0009] In view of this, an object of the present invention is to provide an inspection device, an inspection method, and a wafer manufacturing method that can easily identify the orientation of a workpiece whose first surface includes multiple inclined portions. [Means for solving the problem]

[0010] According to one aspect of the present invention, there is provided an inspection device for inspecting a workpiece having a first surface and a second surface located opposite the first surface and perpendicular to a first direction, the first surface including a plurality of inclined portions each extending along a second direction perpendicular to the first direction and periodically arranged in a third direction perpendicular to both the first and second directions, the inspection device comprising: a target; a camera for capturing images using light emitted from the target, reflected by its surface or passing around it without being blocked by it, and then transmitted through the workpiece or reflected by its first surface; and a controller for controlling the camera, the controller having a memory for storing data indicating the relationship between the position of the target and the second direction and / or the third direction in an image formed by imaging using the light; and a processor for controlling the camera to form an identification image by imaging using the light, and then identifying the second direction and the third direction by referring to the data and the position of the target in the identification image.

[0011] According to another aspect of the present invention, there is provided an inspection device for inspecting a workpiece having a first surface and a second surface located opposite to the first surface and perpendicular to a first direction, the first surface including a plurality of inclined portions each extending along a second direction perpendicular to the first direction and periodically arranged in a third direction perpendicular to both the first direction and the second direction, the inspection device including: a target; a camera for taking an image using light emitted from the target, reflected by a surface of the target or passing around the target without being blocked by it, and then transmitted through the workpiece or reflected by the first surface; and a camera for adjusting the target so that a relative position between the target and the workpiece is either a first relative position or a second relative position different from the first relative position. an inspection device comprising a moving mechanism for moving a target and the workpiece relatively, and a controller for controlling the camera and the moving mechanism, wherein the controller controls the moving mechanism to set the relative position of the target and the workpiece to the first relative position, and then controls the camera to form a first identification image by imaging using the light, and controls the moving mechanism to set the relative position of the target and the workpiece to the second relative position, and then controls the camera to form a second identification image by imaging using the light, and then has a processor that identifies the second direction and the third direction by referring to the position of the target in each of the first identification image and the second identification image.

[0012] According to yet another aspect of the present invention, there is provided an inspection method for inspecting a workpiece having a first surface and a second surface located opposite the first surface and perpendicular to the first direction, and having a plurality of inclined portions on the first surface, each of which extends along a second direction perpendicular to the first direction and is periodically arranged in a third direction perpendicular to both the first and second directions, the inspection method comprising: an imaging step of forming an identification image by imaging using light that is emitted from a target, reflected by its surface or passes around it without being blocked by it, and then transmitted through the workpiece or reflected by its first surface; and an identification step of identifying the second direction and the third direction by referring to data indicating the relationship between the position of the target and the second direction and / or the third direction in an image formed by imaging using the light, which is known in advance, and the position of the target in the identification image.

[0013] According to yet another aspect of the present invention, there is provided an inspection method for inspecting a workpiece having a first surface and a second surface located opposite the first surface and perpendicular to the first direction, and having a plurality of inclined portions on the first surface, each of which extends along a second direction perpendicular to the first direction and is periodically arranged in a third direction perpendicular to both the first and second directions, the inspection method further comprising: an imaging step of forming a first identification image by imaging using light emitted from the target, reflected by its surface or passing around it without being blocked by it, and then passing through the workpiece or reflected by its first surface, with the relative position between the target and the workpiece set to a first relative position; and forming a second identification image by imaging using the light, with the relative position between the target and the workpiece set to a second relative position; and an identification step of identifying the second direction and the third direction by referring to the position of the target in each of the first identification image and the second identification image, after the imaging step.

[0014] According to yet another aspect of the present invention, there is provided a wafer manufacturing process for manufacturing a wafer having a first surface and a second surface located opposite to the first surface and perpendicular to a first direction, the first surface including a plurality of inclined portions that are aligned along a second direction perpendicular to the first direction and are periodically arranged in a third direction perpendicular to both the first and second directions, from an ingot having the second surface and a third surface located opposite to the second surface and parallel to the second surface; an orientation specifying process for specifying the second direction and the third direction after the wafer manufacturing process; and a planarizing process for planarizing the first surface of the wafer after the orientation specifying process. and a direction identification process, the direction identification process including: an imaging process for forming an identification image by imaging using light emitted from the target, reflected by its surface or passing around it without being blocked by it, and then transmitted through the wafer or reflected by its first surface; and an identification process for identifying the second direction and the third direction by referring to data indicating the relationship between the position of the target and the second direction and / or the third direction in the image formed by imaging using the light, which is known in advance, and the position of the target in the identification image, after the imaging process.

[0015] According to yet another aspect of the present invention, there is provided a wafer manufacturing method, comprising: a wafer manufacturing step of manufacturing a wafer having a first surface and a second surface located opposite to the first surface and perpendicular to a first direction, the first surface including a plurality of inclined portions each extending along a second direction perpendicular to the first direction and periodically arranged in a third direction perpendicular to both the first and second directions, from an ingot having the second surface and a third surface located opposite to the second surface and parallel to the second surface; an orientation specifying step of specifying the second direction and the third direction after the wafer manufacturing step; and a planarizing step of planarizing the first surface of the wafer after the orientation specifying step, wherein the orientation specifying step includes: a first identification image is formed by imaging light emitted from the target, reflected by the surface of the target, or passing around the wafer without being blocked by it, and then transmitted through the wafer or reflected by the first surface, with the relative position between the target and the wafer being set to a first relative position; and a second identification image is formed by imaging light with the relative position between the target and the wafer being set to a second relative position; and a specifying step, after the imaging step, of specifying the second direction and the third direction by referring to the positions of the target in the first identification image and the second identification image, respectively.

[0016] Preferably, the wafer manufacturing method of the present invention further comprises a separation layer forming step of forming a separation layer inside the ingot by positioning a focal point of a laser beam inside the ingot and relatively moving the ingot along a direction parallel to the second surface of the ingot, and a dividing step of manufacturing the wafer by dividing the workpiece using the separation layer as a starting point after the separation layer forming step. Additionally, the wafer manufacturing method of the present invention preferably further comprises an alignment step of adjusting the orientation of the wafer so that the second direction coincides with a predetermined direction, a holding step of holding the wafer with the first surface exposed after the alignment step, and a grinding step of grinding the first surface side of the wafer after the holding step. [Effects of the Invention]

[0017] In the present invention, the second direction (specifically, the direction in which each inclined portion extends) and the third direction (specifically, the direction in which multiple inclined portions are arranged) are identified by referring to the position of the target in the identifying image. Therefore, in the present invention, it is possible to easily identify the orientation of a workpiece such as a wafer. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1(A) is a plan view schematically showing an example of a wafer, and FIG. 1(B) is a cross-sectional view showing the wafer shown in FIG. 1(A). [Figure 2] FIG. 2 is a diagram schematically illustrating an example of an inspection device for identifying the orientation of a wafer. [Figure 3] FIG. 3 is a diagram schematically illustrating the path of light that starts at a target, passes through a wafer supported by a support member so that a first surface faces the camera, and then travels toward the camera. [Figure 4] FIG. 4 is a diagram schematically illustrating the path of light that starts at a target, passes through a wafer supported by a support member so that the second surface faces the camera, and then travels toward the camera. [Figure 5] FIG. 5 is a flowchart that schematically illustrates an example of an inspection method that is performed in an inspection apparatus to identify the orientation of a wafer. [Figure 6] FIG. 6 is a diagram schematically illustrating another example of an inspection device for identifying the orientation of a wafer. [Figure 7] FIG. 7 is a diagram schematically illustrating the path of light that starts at the target, is reflected by the first surface of a wafer that is supported by a support member so that the first surface faces the target and the camera, and then travels toward the camera. [Figure 8]FIG. 8 is a diagram showing a schematic diagram of a path of light that starts at the target, is reflected by a first surface of a wafer supported by a support member so that a second surface faces the target and the camera, and then travels toward the camera. [Figure 9] FIG. 9 is a diagram schematically illustrating yet another example of an inspection device for identifying the orientation of a wafer. [Figure 10] FIG. 10 is a flowchart schematically illustrating another example of an inspection method performed in an inspection apparatus to identify the orientation of a wafer. [Figure 11] FIG. 11 is a flow chart that schematically shows an example of a wafer manufacturing method that includes a step performed to identify the orientation of the wafer. [Figure 12] FIG. 12(A) is a perspective view schematically showing an example of an ingot used in the production of wafers, and FIG. 12(B) is a side view schematically showing the ingot shown in FIG. 12(A). [Figure 13] FIG. 13 is a flowchart schematically illustrating an example of the wafer manufacturing process shown in FIG. [Figure 14] FIG. 14(A) is a perspective view that schematically shows the release layer forming step shown in FIG. 13, and FIG. 14(B) is a partially enlarged cross-sectional view that schematically shows the step. [Figure 15] 15(A) and 15(B) are each a partial cross-sectional side view that schematically illustrates the state of the dividing step shown in FIG. [Figure 16] FIG. 16 is a perspective view schematically showing an example of a grinding apparatus for carrying out the planarization step shown in FIG. [Figure 17] FIG. 17 is a flow chart schematically illustrating an example of a planarization process performed in the grinding device. DETAILED DESCRIPTION OF THE INVENTION

[0019] An embodiment of the present invention will be described with reference to the accompanying drawings, in which Fig. 1(A) is a plan view schematically showing an example of a workpiece (here, a wafer) whose orientation is to be specified, and Fig. 1(B) is a cross-sectional view showing the wafer shown in Fig. 1(A).

[0020] 1(A) and 1(B) is manufactured from an ingot made of single crystal SiC and has a thin, disk-like shape. Specific examples of methods for manufacturing the wafer 11 from an ingot will be described later. One surface (first surface) 11a of the wafer 11 is uneven, and the other surface (second surface) 11b is flat.

[0021] In the wafer 11, the c-axis A of SiC is slightly tilted with respect to a line L (i.e., a normal to the second surface 11b) along the thickness direction (first direction) of the wafer 11. For example, the angle (off angle) between the c-axis A and the line L is 1° to 6°, and here is assumed to be 4° for convenience.

[0022] The first surface 11a of the wafer 11 also includes a plurality of linearly extending inclined portions 11c. Each inclined portion 11c is formed so as to be perpendicular to the c-axis A of the SiC, i.e., so that the c-plane of the SiC is exposed at each inclined portion 11c.

[0023] Therefore, the direction in which each inclined portion 11c extends (inclined portion extension direction) is a direction (second direction) perpendicular to the thickness direction of the wafer 11. Moreover, the direction in which the multiple inclined portions 11c are arranged (inclined portion arrangement direction) is a direction (third direction) perpendicular to both the thickness direction of the wafer 11 and the inclined portion extension direction.

[0024] Furthermore, an orientation flat 13 is formed on the side surface of the wafer 11 to facilitate grasping the crystal orientation of the SiC. This orientation flat 13 is located in a second direction when viewed from the center of the wafer 11 and is formed so as to be perpendicular to the second direction. In other words, the orientation flat 13 is formed so as to be perpendicular to the c-plane of the SiC.

[0025] In addition to or instead of the orientation flat 13, another orientation flat (for example, an orientation flat located in a direction other than the second direction (for example, a third direction) when viewed from the center of the wafer 11 and perpendicular to that direction) may be formed on the side of the wafer 11. Furthermore, the mark for facilitating the determination of the crystal orientation of the material of the wafer 11 is not limited to the orientation flat 13, and may be, for example, a notch.

[0026] 2 is a diagram schematically illustrating an example of an inspection device for identifying the orientation of a wafer 11 (specifically, the direction in which the inclined portions extend and the direction in which the inclined portions are arranged). The inspection device 10 shown in FIG. 2 includes a target 12. This target 12 is, for example, a light source capable of emitting light upward or a reflector having a surface capable of reflecting light upward.

[0027] A support member 14 is provided above the target 12. This support member 14 is an annular structure having an opening 14a formed in a portion that overlaps with the target 12 in the vertical direction, and is capable of supporting the wafer 11. Furthermore, a holding mechanism (not shown) for holding the wafer 11 may be connected to the upper surface of the support member 14.

[0028] The holding mechanism includes, for example, a clamp capable of pressing a portion near the outer periphery of the wafer 11 against the support member 14, or a suction source capable of applying suction force to that portion. Furthermore, if the holding mechanism includes a suction source, a groove may be formed on the top surface of the support member 14, the inside of which becomes negative pressure when the suction source is operated.

[0029] A camera 16 is provided above the support member 14. The camera 16 has, for example, an objective lens and an imaging element such as a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor. The camera 16 is oriented downward so that its objective lens faces the target 12.

[0030] The camera 16 can capture an image of the target 12 even when the wafer 11 is supported by the support member 14. That is, the camera 16 can capture an image of the target 12 by using light that is emitted from the target 12 or reflected on its surface and then transmitted through the wafer 11 supported by the support member 14.

[0031] Furthermore, the inspection device 10 includes a controller 18 for controlling the camera 16. The controller 18 includes a memory 18a and a processor 18b. The memory 18a is configured, for example, by a volatile memory such as a dynamic random access memory (DRAM) or a static random access memory (SRAM), and a non-volatile memory such as a solid state drive (SSD) (NAND flash memory) or a hard disk drive (HDD) (magnetic storage device). The processor 18b is configured, for example, by a central processing unit (CPU).

[0032] The memory 18a stores data, programs, etc. used by the processor 18b. This data includes data (identification data) indicating the relationship between the position of the target 12 in an image formed when the target 12 is photographed by the camera 16 and the orientation of the wafer 11. This relationship will be described below with reference to FIGS. 3 and 4.

[0033] 3 is a diagram schematically illustrating a path R1 of light that starts from the target 12, passes through the wafer 11 supported by the support member 14 so that the first surface 11a faces the camera 16, and then travels toward the camera 16. Note that FIG. 3 is drawn on the assumption that the refractive index of the atmosphere in the inspection device 10 is 1.0, the refractive index of the material of the wafer 11, i.e., SiC, is 2.6, and the optical axis O1 of the objective lens 16a of the camera 16 coincides with the above-mentioned straight line L.

[0034] When the wafer 11 is supported by the support member 14 so that the first surface 11a faces the camera 16, light traveling from the target 12 along the optical axis O1 of the objective lens 16a of the camera 16 is refracted at the first surface 11a and travels in a direction that forms an angle of 6.45° with the optical axis O1. This light is then focused by the objective lens 16a and the like to form an image on the sensor surface 16b.

[0035] 4 is a diagram schematically illustrating a path R2 of light that starts from the target 12, passes through the wafer 11 supported by the support member 14 so that the second surface 11b faces the camera 16, and then travels toward the camera 16. Note that, like FIG. 3, FIG. 4 is drawn on the assumption that the refractive index of the atmosphere of the inspection device 10 is 1.0, the refractive index of the material of the wafer 11, i.e., SiC, is 2.6, and the optical axis O1 of the objective lens 16a of the camera 16 coincides with the above-mentioned straight line L.

[0036] When the wafer 11 is supported by the support member 14 so that the second surface 11b faces the camera 16, light traveling from the target 12 along the optical axis O1 of the objective lens 16a of the camera 16 is refracted at the first surface 11a and travels in a direction that forms an angle of 1.54° with the optical axis O1, and is further refracted at the second surface 11b and travels in a direction that forms an angle of 6.41° with the optical axis O1. This light is then focused by the objective lens 16a and the like to form an image on the sensor surface 16b.

[0037] Therefore, the position (imaging position) of the target 12 in the image (identification image) formed by imaging the target 12 using light that has passed through the wafer 11 supported by the support member 14 is shifted from the position (reference position) of the target 12 in the image formed by imaging the target 12 using light that does not pass through the wafer 11.

[0038] Specifically, the imaging position is shifted a specific distance from the reference position in the inclined portion arrangement direction. Therefore, by referencing the displacement vector from the reference position to the imaging position in this image, it is possible to identify the orientation of the wafer 11 (specifically, the direction in which the inclined portions extend and the direction in which the inclined portions are arranged). Furthermore, because the reference position in this image does not change, it is also possible to identify the orientation of the wafer 11 by referencing the position of the target 12 in the identification image.

[0039] The memory 18a stores, for example, a plurality of sets of data, each of which is associated with an imaging position and an orientation of the wafer 11. Furthermore, the memory 18a may store a plurality of sets of data, each of which is associated with a displacement vector and an orientation of the wafer 11. The memory 18a also stores a program for implementing an inspection method for identifying the orientation of the wafer 11.

[0040] The processor 18b reads and executes a program stored in the memory 18a while using the data stored in the memory 18a. For example, the processor 18b reads and executes a program for implementing an inspection method for identifying the orientation of the wafer 11 from the memory 18a.

[0041] 5 is a flowchart that schematically illustrates an example of an inspection method performed in the inspection device 10 to identify the orientation of the wafer 11. In this method, first, an image of the target 12 is captured using light that passes through the wafer 11 supported by the support member 14 to form an image for identification (imaging step S11).

[0042] In this imaging step S11, for example, the processor 18b controls the camera 16 to form an identification image by imaging the target 12 using light transmitted through the wafer 11. Furthermore, if the target 12 is a light source, the processor 18b may control the camera 16 in this way and also control the target 12 to emit light.

[0043] After the imaging step S11, the orientation of the wafer 11 is identified by referring to the identification data stored in the memory 18a and the position of the target 12 in the identification image (identification step S12).

[0044] In this identification step S12, for example, the processor 18b selects one of a plurality of imaging positions stored in the memory 18a, each associated with an orientation of the wafer 11, that corresponds to the position of the target 12 in the identification image. Then, the processor 18b identifies the orientation of the wafer 11 stored in the memory 18a, associated with the selected imaging position, as the actual orientation of the wafer 11.

[0045] In the inspection device 10 shown in Fig. 2 or the inspection method shown in Fig. 5, the orientation of the wafer 11 (specifically, the direction in which the inclined portions extend and the direction in which the inclined portions are arranged) is identified by referring to the position of the target 12 in the identification image. Therefore, in the inspection device 2 shown in Fig. 2 or the inspection method shown in Fig. 5, it is possible to easily identify, for example, the direction in which the orientation flat 13 is formed when viewed from the center of the wafer 11.

[0046] It should be noted that the inspection device 10 shown in Fig. 2 or the inspection method shown in Fig. 5 are one embodiment of the present invention, and the present invention is not limited to the inspection device 10 shown in Fig. 2 or the inspection method shown in Fig. 5. For example, in the imaging step S11 of the present invention, it is sufficient that light is supplied to the wafer 11 so as to pass through the wafer 11, and the imaging step S11 may be performed in a state in which the wafer 11 is supported by a support member having a shape different from that of the support member 14.

[0047] Examples of shapes different from the support member 14 include a shape that can support the wafer 11 with the underside of the portion near the periphery of the wafer 11 partially exposed (for example, a disk-like shape with a portion near the periphery cut out), or a plate-like shape with through holes formed at any location. A support member having such a shape is preferable compared to the support member 14 in that it can reduce the likelihood of the wafer 11 bending when supporting the wafer 11, and can be easily manufactured due to its simple configuration.

[0048] Furthermore, the imaging step S11 of the present invention may be performed in a state where the wafer 11 is held by a transfer arm for transporting the wafer 11, rather than in a state where the wafer 11 is supported by the support member 14. When the imaging step S11 is performed in a state where the wafer 11 is held by a transfer arm, this is preferable in that the support member 14 is not required and that the orientation of the wafer 11 can be adjusted while the wafer 11 is held by the transfer arm after the orientation of the wafer 11 has been identified.

[0049] Furthermore, the imaging step S11 of the present invention may be performed in a state in which the wafer 11 is supported by a support member made of a material that transmits light traveling from the target 12 to the wafer 11, instead of the support member 14. Furthermore, the imaging step S11 of the present invention may be performed in a state in which the wafer 11 is sandwiched between a support member made of such a material and a protective member made of the same material. When the imaging step S11 is performed in such a state, the likelihood of the wafer 11 bending when being supported can be reduced compared to when the imaging step S11 is performed in a state in which the wafer 11 is supported by the support member 14, and the simple configuration makes it easy to manufacture, which is preferable.

[0050] Furthermore, in the present invention, light that passes through the periphery of the target 12 without being blocked by it may be used for imaging instead of light emitted from or reflected on the surface of the target 12. In this case, for example, a surface light source (backlight) for emitting highly directional light upward is provided below the target 12.

[0051] Furthermore, in this case, the target 12 is, for example, a shielding plate capable of blocking the light emitted from this surface light source. When an image is captured by the camera 16 with light emitted from this surface light source, an image including a silhouette of a shape corresponding to the target 12 is formed. Therefore, the position of the target 12 can be identified even when referring to this image.

[0052] Furthermore, in the present invention, light reflected on the first surface 11a of the wafer 11 may be used for imaging instead of light transmitted through the wafer 11. Fig. 6 is a diagram schematically illustrating an example of an inspection device for identifying the orientation of the wafer 11 by referring to the position of a target in an image formed by imaging the target using light reflected on the first surface 11a of the wafer 11.

[0053] 6 includes a support member 22. The support member 22 is, for example, a structure having a disk-like shape, and is capable of supporting the wafer 11. Furthermore, a holding mechanism (not shown) for holding the wafer 11 on the upper surface of the support member 22 may be connected to the support member 22.

[0054] This holding mechanism includes, for example, a clamp capable of pressing a portion near the outer periphery of the wafer 11 against the support member 22, or a suction source capable of applying suction force to that portion. Furthermore, if the holding mechanism includes a suction source, a groove may be formed on the upper surface of the support member 22, the inside of which becomes negative pressure when the suction source is operated.

[0055] A target 24 is provided above a portion near one end of the support member 22. This target 24 is, for example, a light source capable of emitting light toward a portion near the center of the support member 22, or a reflector having a surface capable of reflecting light toward that portion.

[0056] A camera 26 is provided above a portion near the other end of the support member 22. This camera 26 has, for example, an objective lens and an imaging element such as a CCD image sensor or a CMOS image sensor. The objective lens of the camera 26 is provided so as to face a portion near the center of the support member 22.

[0057] The camera 26 can capture an image of the target 24 when the wafer 11 is supported by the support member 22. That is, the camera 26 can capture an image of the target 24 by using light that is emitted from the target 24 or reflected on the surface of the target 24 and then reflected on the first surface 11 a of the wafer 11 supported by the support member 22.

[0058] Furthermore, the inspection device 20 includes a controller 28 for controlling the camera 26. The controller 28 includes a memory 28a and a processor 28b. The memory 28a is configured, for example, by a volatile memory such as a DRAM or an SRAM, and a non-volatile memory such as an SSD or an HDD. The processor 18b is configured, for example, by a CPU or the like.

[0059] The memory 28a stores data, programs, etc. used by the processor 28b. This data includes data (identification data) indicating the relationship between the position of the target 24 in an image formed when the target 24 is imaged by the camera 26 and the orientation of the wafer 11. This relationship will be described below with reference to FIGS. 7 and 8.

[0060] 7 is a diagram schematically illustrating a path R3 of light that starts at the target 24, is reflected by the first surface 11a of the wafer 11 that is supported by the support member 22 so that the first surface 11a faces the target 24 and the camera 26, and then heads toward the camera 26. Note that Fig. 7 is drawn on the assumption that the refractive index of the atmosphere in the inspection device 20 is 1.0, the refractive index of the material of the wafer 11, i.e., SiC, is 2.6, and the angle between the traveling direction of the light from the target 24 toward the wafer 11 and the above-mentioned line L and the angle between the optical axis O2 of the objective lens 26a of the camera 26 and the line L are each 45°.

[0061] When the wafer 11 is supported by the support member 22 so that the first surface 11a faces the target 24 and the camera 26, light traveling from the target 24 toward the wafer 11 is reflected by the first surface 11a and travels in a direction that forms an angle of 41° with the line L. This light is then focused by the objective lens 26a and the like to form an image on the sensor surface 26b.

[0062] 8 is a diagram schematically illustrating a path R4 of light that starts at the target 24, is reflected by the first surface 11a of the wafer 11 that is supported by the support member 22 so that the second surface 11b faces the target 24 and the camera 26, and then heads toward the camera 26. Note that, similar to FIG. 7, FIG. 8 is drawn on the assumption that the refractive index of the atmosphere in the inspection device 20 is 1.0, the refractive index of the material of the wafer 11, i.e., SiC, is 2.6, and the angle between the traveling direction of the light from the target 24 toward the wafer 11 and the above-mentioned line L and the angle between the optical axis O2 of the objective lens 26a of the camera 26 and the line L are each 45°.

[0063] When the wafer 11 is supported by the support member 22 so that the second surface 11b faces the target 24 and the camera 26, light traveling from the target 24 toward the wafer 11 is refracted at the second surface 11b of the wafer 11, traveling in a direction that forms an angle of 15.78° with the line L, then reflected at the first surface 11a, traveling in a direction that forms an angle of 7.78° with the line L, and then refracted at the second surface 11b, traveling in a direction that forms an angle of 20.61° with the line L. This light is then focused by the objective lens 26a and the like, and forms an image on the sensor surface 26b.

[0064] Therefore, the position (imaging position) of the target 24 in the image (identification image) formed by imaging the target 24 using light reflected on the first surface 11a of the wafer 11 supported by the support member 22 is shifted from the position (reference position) of the target 24 in the image formed by imaging the target 24 using light reflected on a flat surface.

[0065] Specifically, the imaging position is a position shifted a specific distance from the reference position in the inclined portion arrangement direction. Therefore, by referencing the displacement vector from the reference position to the imaging position in this image, it is possible to identify the orientation of the wafer 11 (specifically, the inclined portion extension direction and inclined portion arrangement direction). Furthermore, because the reference position in this image does not change, it is also possible to identify the orientation of the wafer 11 by referencing the position of the target 24 in the identification image.

[0066] The memory 28a stores, for example, a plurality of sets of data, each of which is associated with an imaging position and an orientation of the wafer 11. The memory 28a may also store a plurality of sets of data, each of which is associated with a displacement vector and an orientation of the wafer 11. The memory 28a also stores a program for implementing an inspection method for identifying the orientation of the wafer 11.

[0067] Processor 28b reads and executes a program stored in memory 28a while using the data stored in memory 28a. For example, processor 28b reads and executes a program for implementing the inspection method shown in Fig. 5 from memory 18a. Note that the procedure for implementing the inspection method shown in Fig. 5 in inspection device 20 is similar to the procedure for implementing the inspection method shown in Fig. 5 in inspection device 10, and therefore a description thereof will be omitted.

[0068] Furthermore, in the present invention, instead of the identification data, a plurality of identification images may be used to identify the orientation of the wafer 11. Fig. 9 is a diagram schematically illustrating an example of an inspection device for identifying the orientation of the wafer 11 by referring to the positions of targets in each of a plurality of identification images.

[0069] 9 includes a movement mechanism 32 for moving the support member 14 in addition to the components of the inspection device 10 shown in Fig. 2. This movement mechanism 32 includes, for example, a ball screw or the like for raising and lowering the support member 14. Furthermore, this movement mechanism 32 is controlled by the controller 18.

[0070] 10 is a flowchart that schematically shows an example of an inspection method for identifying the orientation of the wafer 11, which is carried out in the inspection device 30. In this method, first, images of the target 12 are taken with the wafer 11 positioned at different heights to form a first identification image and a second identification image (imaging step S13).

[0071] In this imaging step S13, first, the processor 18b controls the moving mechanism 32 to position the support member 14 at a position close to the target 12 (first relative position), i.e., at a relatively low position. Next, the processor 18b controls the camera 16 to form a first identification image by capturing an image of the target 12 using light reflected by the first surface 11a of the wafer 11.

[0072] Next, the processor 18b controls the moving mechanism 32 to position the support member 14 at a position (second relative position) far from the target 12, i.e., at a relatively high position. Next, the processor 18b controls the camera 16 to form a second identification image by capturing an image of the target 12 using light reflected by the first surface 11a of the wafer 11.

[0073] If the target 12 is a light source, the processor 18b may control the camera 16 when forming the first identification image and the second identification image, and may also control the target 12 to emit light.

[0074] Here, the imaging position in the first identification image is shifted a specific distance in the inclined portion arrangement direction from the imaging position in the second identification image, so it is possible to identify the orientation of the wafer 11 (specifically, the inclined portion extension direction and the inclined portion arrangement direction) by referring to the displacement vector from the imaging position in the first identification image to the imaging position in the second identification image.

[0075] In consideration of this, in this method, after the imaging step S13, the orientation of the wafer 11 is identified by referring to the positions of the target 12 in each of the first identification image and the second identification image (identification step S14).

[0076] In this identification step S14, for example, the processor 18b selects a displacement vector corresponding to a displacement vector from an imaging position in the first identification image to an imaging position in the second identification image from among a plurality of displacement vectors stored in the memory 18a, each of which is associated with an orientation of the wafer 11. Then, the processor 18b identifies the orientation of the wafer 11 stored in the memory 18a in association with the selected displacement vector as the actual orientation of the wafer 11.

[0077] In an inspection device for identifying the orientation of the wafer 11 by referring to the position of the target in each of a plurality of identification images, a moving mechanism for raising and lowering the target 12 may be provided instead of or in addition to the moving mechanism 32 for raising and lowering the support member 14. That is, in this inspection device, the support member 14 for supporting the wafer 11 and the target 12 need only be movable relative to each other, and there are no limitations on the specific structure.

[0078] The present invention may also be a wafer manufacturing method including steps performed to identify the orientation of the wafer 11 (specifically, the imaging step S11 and the identifying step S12 shown in FIG. 5 or the imaging step S13 and the identifying step S14 shown in FIG. 10). Fig. 11 is a flowchart schematically illustrating an example of such a wafer manufacturing method.

[0079] In this method, wafers 11 are manufactured from ingots (wafer manufacturing step S2) before an orientation specifying step S1 for specifying the orientation of the wafers 11. Fig. 12(A) is a perspective view schematically showing an example of an ingot used to manufacture the wafers 11, and Fig. 12(B) is a side view schematically showing the ingot shown in Fig. 12(A).

[0080] 12(A) and 12(B) is made of a single crystal of SiC and has a thick cylindrical shape. The front surface 1a (the surface that will become the second surface 11b of the wafer 11) and the back surface (third surface) 1b of the ingot 1 are flat and parallel to each other.

[0081] In the ingot 1, the c-axis A of SiC is slightly tilted with respect to a line L (i.e., a normal line to the front surface 1a and the back surface 1b) along the thickness direction of the ingot 1. For example, the angle (off angle) between the c-axis A and the line L is 1° to 6°, and here it is assumed to be 4° for convenience.

[0082] Furthermore, an orientation flat 3 is formed on the side surface of the ingot 1 to facilitate grasping the crystal orientation of the SiC. This orientation flat 3 is formed so as to be perpendicular to the c-plane of the SiC.

[0083] Note that, in addition to the orientation flat 3, another orientation flat may be formed on the side surface of the ingot 1. Furthermore, the mark for making it easier to grasp the crystal orientation of the material of the ingot 1 is not limited to the orientation flat 3, and may be, for example, a notch.

[0084] Fig. 13 is a flow chart showing an example of the wafer manufacturing process S2. In this wafer manufacturing process S2, first, a separation layer is formed inside the ingot (separation layer forming process S21). Fig. 14(A) is a perspective view showing the separation layer forming process S21, and Fig. 14(B) is a partially enlarged cross-sectional view showing the process.

[0085] Note that the direction indicated by the arrow X (X direction) and the direction indicated by the arrow Y (Y direction) shown in FIGS. 14(A) and 14(B) are directions that are perpendicular to each other on a horizontal plane, and the direction indicated by the arrow Z (Z direction) is a direction (vertical direction) that is perpendicular to both the X direction and the Y direction.

[0086] This peeling layer forming step S21 is performed in a laser beam irradiation device 42. The laser beam irradiation device 42 includes a chuck table 44. This chuck table 44 has a circular upper surface, and a porous plate (not shown) is exposed on this upper surface.

[0087] Furthermore, this porous plate is connected to a suction source (not shown), such as an ejector, via a flow path formed inside the chuck table 44. When this suction source is operated, a suction force acts on the space near the upper surface of the porous plate. Therefore, when the suction source is operated with the ingot 1 placed on the chuck table 44, a suction force acts from the porous plate to the ingot 1, holding the ingot 1 on the upper surface of the chuck table 44.

[0088] The chuck table 44 is also connected to a rotation mechanism (not shown). This rotation mechanism includes, for example, a pulley and a motor. When the rotation mechanism operates, the chuck table 44 rotates around a rotation axis that passes through the center of its upper surface (the upper surface of the porous plate) and is a straight line along the Z direction. For example, the rotation mechanism rotates the chuck table 44 so that the orientation flat 3 of the ingot 1 held on the upper surface of the chuck table 44 is parallel to the Y direction.

[0089] A laser head 46 is provided above the chuck table 44. This laser head 46 is provided at the tip of a cylindrical housing 48 extending along the Y direction. The laser head 46 houses an optical system such as a condenser lens and a mirror, and the housing 48 houses an optical system such as a mirror and / or a lens.

[0090] The base end of the housing 48 is connected to a movement mechanism (not shown). This movement mechanism includes, for example, a ball screw and a motor for rotating the screw shaft of the ball screw. When the movement mechanism is operated, the housing 48 and the laser head 46 move along the X, Y, and / or Z directions.

[0091] Furthermore, the laser beam irradiation device 42 is provided with a laser oscillator (not shown) containing, for example, Nd:YAG or the like as a laser medium. This laser oscillator generates a pulsed laser beam LB having a wavelength (e.g., 1030 nm or 1064 nm) that is transmitted through the material of the ingot 1. Then, after the output (power) of the laser beam LB is adjusted by an attenuator (not shown), it is emitted directly downward from the laser head 46 via an optical system housed in the housing 48 and the laser head 46.

[0092] Additionally, a camera 50 capable of capturing an image of the area directly below is provided on the side of the housing 48. The camera 50 includes a light source such as an LED (Light Emitting Diode), an objective lens, and an imaging element such as a CCD image sensor or a CMOS image sensor.

[0093] When performing the peeling layer forming step S21 in the laser beam irradiation device 42, first, the ingot 1 is placed on the chuck table 44 with the surface 1a facing upward. Next, the suction source is operated so that the ingot 1 is held on the upper surface of the chuck table 44. Next, the camera 50 is operated so as to capture an image of the ingot 1.

[0094] Next, with reference to the image formed by this imaging, the rotation mechanism rotates the chuck table 44 so that the orientation flat 3 is parallel to the Y direction, for example. Next, the movement mechanism moves the laser head 46 along the X direction and / or the Y direction so that a region of the ingot 1 near one end in the Y direction is positioned in the X direction as seen from the laser head 46 in a plan view.

[0095] Next, the movement mechanism moves the laser head 6 along the Z direction so that the focal point at which the laser beam LB emitted from the laser head 46 is focused is positioned at a predetermined target depth from the surface 1a of the ingot 1. Next, while emitting the laser beam LB from the laser head 46, the movement mechanism moves the laser head 46 along the X direction so that the focal point passes over the ingot 1 in a plan view.

[0096] That is, the laser beam LB is irradiated onto the ingot 1 with its scanning direction being perpendicular to the orientation flat 3. As a result, a portion (modified portion) 5 in which the crystal structure of the material (single crystal SiC) is disrupted is formed inside the ingot 1, centered on the focal point where the laser beam LB is focused.

[0097] Furthermore, when the modified portion 5 is formed inside the ingot 1, the volume of the ingot 1 expands, causing internal stress in the ingot 1. If this internal stress is large, cracks 7 extend from the modified portion 5 along the c-plane of the SiC, thereby relieving the internal stress.

[0098] In addition, in the peeling layer formation process S21, the irradiation conditions of the laser beam LB (e.g., its output) may be set so as to generate internal stress to the extent that cracks 7 do not extend from the modified area 5 (see Figure 14(A)), or the irradiation conditions of the laser beam LB may be set so as to generate internal stress to the extent that cracks 7 extend from the modified area 5 (see Figure 14(B)).

[0099] For example, from the viewpoint of reducing the amount of modified portions 5 remaining in wafers 11 produced from the ingot 1, it is preferable to prevent cracks 7 from extending from the modified portions 5 by, for example, relatively reducing the output of the laser beam LB. On the other hand, from the viewpoint of facilitating division of the ingot 1 in the division step S22 described below, it is preferable to allow cracks 7 to extend from the modified portions 5 by, for example, relatively increasing the output of the laser beam LB.

[0100] Next, the movement mechanism moves the laser head 46 along the Y direction so that, in a plan view, the laser head 46 is positioned in the X direction when viewed from a region of the ingot 1 that is slightly inside the region that has already been irradiated with the laser beam LB. Next, the direction opposite to the X direction is set as the scanning direction of the laser beam LB, and the laser beam LB is irradiated onto the ingot 1 as described above.

[0101] As a result, a new modified region 5 is formed inside the ingot 1 so as to be aligned parallel to the existing modified region 5. Furthermore, if the internal stress generated in the ingot 1 due to the formation of the new modified region 5 is large, a crack 7 will also extend from this modified region 5 along the c-plane of SiC.

[0102] Furthermore, if the internal stress is large enough that cracks 7a extending along the c-plane of SiC from each of a pair of modified regions 5 arranged parallel to each other approach each other, cracks 7b will be generated that extend across the c-plane of SiC to connect these cracks 7a (see Figure 14(B)).

[0103] Furthermore, the relative movement of the ingot 1 along the Y direction and the position where the focal point where the laser beam LB is focused is formed (specifically, the movement of the laser head 46) and the irradiation of the laser beam LB onto the ingot 1 with the X direction or the opposite direction as the scanning direction of the laser beam LB are alternately repeated.

[0104] Then, when the laser beam LB is irradiated onto a region of the ingot 1 near the other end in the Y direction, the repetition of the above-mentioned operations is terminated. As a result, multiple rows of modified regions 5, each extending perpendicular to the orientation flat 3, are formed inside the ingot 1. Alternatively, as a result, a peeling layer 9 including the multiple rows of modified regions 5 and cracks 7 extending from each modified region 5 is formed inside the ingot 1.

[0105] After the separation layer forming step S21, the ingot 1 is divided at the separation layer 9 as a starting point to manufacture wafers 11 (division step S22). Figures 15(A) and 15(B) are partial cross-sectional side views each showing a schematic view of the division step S22.

[0106] This dividing step S22 is performed in a suction device 52. The suction device 52 includes a chuck table 54. The chuck table 54 has a circular upper surface, and a porous plate (not shown) is exposed on this upper surface.

[0107] Furthermore, this porous plate is connected to a lower suction source (not shown), such as a vacuum pump, via a flow path formed inside the chuck table 54. When this lower suction source is operated, a suction force acts on the space near the upper surface of the porous plate.

[0108] Therefore, when the lower suction source is operated with the ingot 1 placed on the chuck table 54 , a suction force acts on the ingot 1 from the porous plate, and the ingot 1 is held on the upper surface of the chuck table 54 .

[0109] A suction plate 56 is provided above the chuck table 54. A plurality of suction ports are formed in the lower surface of the suction plate 56, and each suction port is connected to an upper suction source (not shown), such as a vacuum pump, via a suction path formed inside the suction plate 56. When the upper suction source is operated, a suction force acts on the space near the lower surface of the suction plate 56.

[0110] The lower end of a support shaft 58 is fixed to the upper surface of the suction plate 56, and an elevation mechanism (not shown) is connected to the upper end of the support shaft 58. This elevation mechanism includes, for example, a ball screw and a motor for rotating the screw shaft of the ball screw. When the elevation mechanism is operated, the support shaft 58 and the suction plate 56 move up and down.

[0111] When performing the dividing step S22 in the suction device 52, first, with the chuck table 54 and the suction plate 56 sufficiently spaced apart, the ingot 1 having the peeling layer 9 formed therein is placed on the holding surface of the chuck table 54 with the surface 1a facing upward. Next, the lower suction source is operated so that the ingot 1 is held on the holding surface of the chuck table 54.

[0112] Next, the lifting mechanism lowers the suction plate 56 so that the lower surface of the suction plate 56 contacts the front surface 1a of the ingot 1 (see FIG. 15(A)). Next, the upper suction source is operated so that the front surface 1a of the ingot 1 is sucked upward. Next, the lifting mechanism raises the suction plate 56 so that the suction plate 56 is separated from the chuck table 54 (see FIG. 15(B)).

[0113] In this case, an external force is applied to the ingot 1 such that the front surface 1a side and the back surface 1b side of the ingot 1 are separated. As a result, new cracks 7 extend from the modified portion 5 and / or existing cracks 7 extend further. As a result, the ingot 1 is split starting from the peeling layer 9.

[0114] As a result, a wafer 11 is produced in which a first surface 11a includes a plurality of inclined portions 11c. Furthermore, a newly exposed surface (first surface) 1c of the remaining ingot 1 has a shape similar to that of the first surface 11a of the wafer 11. That is, the first surface 1c of the ingot 1 includes a plurality of inclined portions similar to the plurality of inclined portions 11c.

[0115] 11, after the orientation specifying step S1, the first surface 11a of the wafer 11 is flattened (flattening step S3). Fig. 16 is a perspective view schematically showing an example of a grinding device for performing the flattening step S3. The grinding device 62 shown in Fig. 16 includes a chuck table 64.

[0116] The chuck table 64 has a circular upper surface, and the porous plate 66 is exposed on the upper surface. The porous plate 66 is smaller than the wafer 11 in plan view and has a shape similar to the wafer 11.

[0117] That is, the outer periphery of the upper surface of the porous plate 66 includes an arc-shaped portion 66a and a linear portion (straight portion) 66b. The center C1 of the straight portion 66b is located in a predetermined direction D when viewed from the center C0 of the upper surface of the porous plate 66.

[0118] Furthermore, the porous plate 66 is connected to a suction source (not shown), such as an ejector, via a flow path formed inside the chuck table 64. When this suction source is operated, a suction force acts on the space near the upper surface of the porous plate 66. Therefore, when the suction source is operated with the wafer 11 placed on the chuck table 64, a suction force acts on the wafer 11 from the porous plate 66, and the wafer 11 is held on the upper surface of the chuck table 64.

[0119] The chuck table 64 is also connected to a horizontal movement mechanism (not shown). This horizontal movement mechanism includes, for example, a ball screw and a motor connected to the ball screw. Alternatively, the horizontal movement mechanism may include a turntable that supports the chuck table 64 and a motor for rotating the turntable. When this horizontal movement mechanism is operated, the chuck table 64 moves in the horizontal direction.

[0120] The chuck table 64 is also connected to a rotation mechanism (not shown). This rotation mechanism includes, for example, a motor and a pulley. When this rotation mechanism is operated, the chuck table 64 rotates around a rotation axis that is a straight line passing through the center C0 of the upper surface of the chuck table 64 (i.e., the center C0 of the upper surface of the porous plate 66).

[0121] A grinding unit 68 is provided above the chuck table 64. The grinding unit 68 has a cylindrical spindle 70 that extends vertically. The top surface of a disk-shaped wheel mount 72 made of stainless steel or the like is fixed to the tip (lower end) of the spindle 70.

[0122] Additionally, an annular grinding wheel 74 having an outer diameter approximately equal to the diameter of the wheel mount 72 is removably attached to the lower part of the wheel mount 72. This grinding wheel 74 has an annular wheel base 74a.

[0123] The wheel base 74a is made of, for example, stainless steel, and has a plurality of grinding wheels 74b arranged at approximately equal angular intervals on its underside along the circumferential direction of the wheel base 74a. Each of the plurality of grinding wheels 74b has abrasive grains such as diamond or cBN (cubic boron nitride) dispersed in a binder such as a vitrified bond or a resin bond.

[0124] The base end (upper end) of the spindle 70 is connected to a rotary drive source (not shown) such as a motor. When this rotary drive source is operated, the spindle 70, wheel mount 72, and grinding wheel 74 rotate around a rotation axis that passes through the center of the spindle 70 and is aligned in the vertical direction.

[0125] The grinding unit 68 is also connected to a vertical movement mechanism (not shown). This vertical movement mechanism includes, for example, a ball screw and a motor connected to the ball screw. When the vertical movement mechanism is operated, the grinding unit 68 moves in the vertical direction.

[0126] 17 is a flowchart schematically illustrating an example of the planarization step S3 performed in the grinding apparatus 62. In this planarization step S3, first, the orientation of the wafer 11 is adjusted (alignment step S31). Specifically, in the alignment step S31, the orientation of the wafer 11 is adjusted so that the orientation flat 13 is located when viewed from the center of the wafer 11 and the direction perpendicular to the orientation flat 13 (specifically, the direction in which the inclined portion extends) coincides with the predetermined direction D.

[0127] In addition, if an orientation flat is formed on the wafer 11 instead of the orientation flat 13, which is located in a direction other than the direction in which the inclined portions extend (for example, the direction in which the inclined portions are arranged) when viewed from the center of the wafer 11 and is perpendicular to that direction, in the alignment process S31, the orientation of the wafer 11 is adjusted so that that direction coincides with the above-mentioned specified direction D.

[0128] After the alignment step S31, the wafer 11 is held with the first surface 11a exposed (holding step S32). Specifically, in the holding step S32, the wafer 11 is placed on the chuck table 64 so that it covers the porous plate 66 and the first surface 11a faces upward. Next, the suction source is operated so that the wafer 11 is held on the upper surface of the chuck table 64.

[0129] After the holding step S32, the first surface 11a side of the wafer 11 is ground (grinding step S33). Specifically, in the grinding step S33, first, the chuck table 64 is moved horizontally so that the trajectories of the multiple grinding stones 74b when the grinding wheel 74 is rotated overlap the center of the wafer 11 in a plan view.

[0130] Next, the grinding wheel 74 is lowered while rotating both the chuck table 64 and the grinding wheel 74. This causes the multiple grinding stones 74b to press against the first surface 11a of the wafer 11, grinding the first surface 11a side of the wafer 11. As a result, the first surface 11a of the wafer 11 is flattened.

[0131] The present invention may also be a wafer manufacturing method that includes the orientation specifying step S1 and the wafer manufacturing step S2 but does not include the planarization step S3. Also, the present invention may also be an inspection method that includes the orientation specifying step S1 and the planarization step S3 but does not include the wafer manufacturing step S2.

[0132] Furthermore, the workpiece whose orientation is to be identified in the present invention may be the ingot 1 remaining after the wafer 11 is produced, i.e., the ingot 1 having a first surface 1c including a plurality of inclined portions. Note that the inspection method and the inspection method for inspecting the ingot 1 to identify its orientation are the same as those described above except that the wafer 11 is replaced with the ingot 1, and therefore a description thereof will be omitted.

[0133] In addition, the structures and methods according to the above-described embodiments can be modified as appropriate without departing from the scope of the present invention. [Explanation of symbols]

[0134] 1: Ingot (1a: front surface, 1b: back surface, 1c: newly exposed surface (first surface)) 3: Orientation Flat 5: Modification section 7: Crack (7a: Crack extending along the c-plane of SiC) (7b: A crack extending to intersect with the c-plane of SiC) 9: Peeling layer 10: Inspection equipment 11: Wafer (11a: One side (first side), 11b: Other side (second side), 11c: Slanted part) 12: Target 13: Orientation Flat 14: Support member 16: Camera (16a: Objective lens, 16b: Sensor surface) 18: Controller (18a: memory, 18b: processor) 20: Inspection equipment 22: Support member 24: Target 26: Camera 28: Controller (28a: memory, 28b: processor) 30: Inspection equipment 32: Movement mechanism 42: Laser beam irradiation device 44: Chuck table 46: Laser head 48: Housing 50: Camera 52:Suction device 54: Chuck table 56: Suction plate 58: Support shaft 62: Grinding equipment 64: Chuck table 66: Porous plate (66a: arc-shaped portion, 66b: linear portion) 68: Grinding unit 70:Spindle 72: Wheel mount 74: Grinding wheel (74a: wheel base, 74b: grinding stone)

Claims

1. An inspection device for inspecting a workpiece, the inspection device having a first surface and a second surface located opposite the first surface and perpendicular to a first direction, the first surface including a plurality of inclined portions each extending along a second direction perpendicular to the first direction and periodically arranged in a third direction perpendicular to both the first direction and the second direction, Target and a camera for capturing an image using light emitted from the target, reflected by the surface of the target, or passing through the surrounding area without being blocked by the target, and then transmitted through the workpiece or reflected by the first surface of the workpiece; a controller for controlling the camera, The controller a memory for storing data indicating a relationship between the position of the target in an image formed by imaging using the light and the second direction and / or the third direction; An inspection device having a processor that controls the camera to form an image for identification by imaging using the light, and then identifies the second direction and the third direction by referring to the data and the position of the target in the image for identification.

2. An inspection device for inspecting a workpiece, the inspection device having a first surface and a second surface located opposite the first surface and perpendicular to a first direction, the first surface including a plurality of inclined portions each extending along a second direction perpendicular to the first direction and periodically arranged in a third direction perpendicular to both the first direction and the second direction, Target and a camera for capturing an image using light emitted from the target, reflected by the surface of the target, or passing through the surrounding area without being blocked by the target, and then transmitted through the workpiece or reflected by the first surface of the workpiece; a movement mechanism for relatively moving the target and the workpiece so that the relative positions of the target and the workpiece are either a first relative position or a second relative position different from the first relative position; a controller for controlling the camera and the movement mechanism, The controller controls the moving mechanism to set the relative position between the target and the workpiece to the first relative position, then controls the camera to form a first identification image by imaging using the light, and controls the moving mechanism to set the relative position between the target and the workpiece to the second relative position, then controls the camera to form a second identification image by imaging using the light, and then identifies the second direction and the third direction by referring to the position of the target in each of the first identification image and the second identification image.

3. An inspection method for inspecting a workpiece having a first surface and a second surface located opposite the first surface and perpendicular to a first direction, the first surface including a plurality of inclined portions each extending along a second direction perpendicular to the first direction and periodically arranged in a third direction perpendicular to both the first direction and the second direction, an imaging step of forming an image for identification by imaging using light emitted from the target, reflected by the surface of the target, or passing around the target without being blocked by the surface, and then transmitted through the workpiece or reflected by the first surface of the workpiece; an identification step of identifying the second direction and the third direction by referring to data indicating a relationship between the position of the target in an image formed by imaging using the light, which is known in advance, and the second direction and / or the third direction, and the position of the target in the identification image, after the imaging step; Inspection methods available.

4. An inspection method for inspecting a workpiece having a first surface and a second surface located opposite the first surface and perpendicular to a first direction, the first surface including a plurality of inclined portions each extending along a second direction perpendicular to the first direction and periodically arranged in a third direction perpendicular to both the first direction and the second direction, an imaging step of forming a first identification image by imaging using light emitted from the target, reflected by the surface of the target or passing around the workpiece without being blocked by it, and then transmitted through the workpiece or reflected by the first surface of the target, with the relative position between the target and the workpiece being set to a first relative position, and forming a second identification image by imaging using the light, with the relative position between the target and the workpiece being set to a second relative position; an identifying step of identifying the second direction and the third direction by referring to positions of the target in the first identification image and the second identification image, respectively, after the imaging step; The inspection method further comprises:

5. a wafer manufacturing process for manufacturing a wafer having a first surface and a second surface located opposite to the first surface and perpendicular to a first direction, the first surface including a plurality of inclined portions each extending along a second direction perpendicular to the first direction and periodically arranged in a third direction perpendicular to both the first direction and the second direction, from an ingot having the second surface and a third surface located opposite to the second surface and parallel to the second surface; an orientation specifying step of specifying the second direction and the third direction after the wafer manufacturing step; a planarization step of planarizing the first surface of the wafer after the orientation identification step; The orientation identification step includes: an imaging step of forming an image for identification by imaging using light emitted from the target, reflected by the surface of the target or passing around the target without being blocked by the surface, and then transmitted through the wafer or reflected by the first surface of the wafer; A wafer manufacturing method including, after the imaging process, an identification process of identifying the second direction and the third direction by referring to data indicating the relationship between the position of the target in an image formed by imaging using the light, which has been previously determined, and the second direction and / or the third direction, and the position of the target in the identification image.

6. a wafer manufacturing process for manufacturing a wafer having a first surface and a second surface located opposite to the first surface and perpendicular to a first direction, the first surface including a plurality of inclined portions each extending along a second direction perpendicular to the first direction and periodically arranged in a third direction perpendicular to both the first direction and the second direction, from an ingot having the second surface and a third surface located opposite to the second surface and parallel to the second surface; an orientation specifying step of specifying the second direction and the third direction after the wafer manufacturing step; a planarization step of planarizing the first surface of the wafer after the orientation identification step; The orientation identification step includes: an imaging step of forming a first identification image by imaging using light emitted from the target, reflected by the surface of the target or passing around the wafer without being blocked by it, and then transmitted through the wafer or reflected by the first surface of the target, with the relative position between the target and the wafer being set to a first relative position, and forming a second identification image by imaging using the light, with the relative position between the target and the wafer being set to a second relative position; a specifying step of specifying the second direction and the third direction by referring to the positions of the target in the first identification image and the second identification image, respectively, after the imaging step.

7. The wafer manufacturing process includes: a separation layer forming step of forming a separation layer inside the ingot by relatively moving the focal point of the laser beam and the ingot along a direction parallel to the second surface of the ingot while the focal point is positioned inside the ingot; 7. The method for producing a wafer according to claim 5, further comprising, after the separation layer forming step, a dividing step of dividing the ingot using the separation layer as a starting point to produce wafers.

8. The planarization step includes: an alignment step of adjusting the orientation of the wafer so that the second direction coincides with a predetermined direction; a holding step of holding the wafer with the first surface exposed after the alignment step; 7. The method for manufacturing a wafer according to claim 5, further comprising, after the holding step, a grinding step of grinding the first surface side of the wafer.

Images