Processing method and processing apparatus, and method for manufacturing wafers

Abstract

Regardless of the workpiece, it efficiently reduces the unevenness of the workpiece while keeping costs down. [Solution] The method comprises a holding step in which a first workpiece is held in a first holding part and a second workpiece made of the same material as the first workpiece is held in a second holding part, and a surface irregularity reduction step in which the first workpiece and the second workpiece are moved relative to each other in the in-plane direction of the contact surfaces of the first workpiece and the second workpiece while they are in contact with each other, thereby reducing the irregularities on the contact surfaces of the first workpiece and the second workpiece, wherein in the surface irregularity reduction step, the first workpiece and the second workpiece are brought into contact such that the direction of extension of the irregularities on the contact surface of the first workpiece and the direction of extension of the irregularities on the contact surface of the second workpiece intersect.

Description

Technical Field

[0001] The present invention relates to a processing method, a processing apparatus, and a method for manufacturing a wafer.

Background Art

[0002] For the manufacture of electronic devices such as ICs (Integrated Circuits) and LSIs (Large Scale Integration), wafers made of materials such as Si (silicon) are used. Also, for the manufacture of power devices and optical devices such as LEDs (Light Emitting Diodes) and LDs (Laser Diodes), wafers made of hexagonal single crystals such as SiC (silicon carbide) and GaN (gallium nitride) are used.

[0003] In the method for generating a wafer described in Patent Document 1, the condensing point of a laser beam having a wavelength that is transmissive to an ingot made of a material is positioned inside the ingot, and the laser beam is irradiated to form a peeling layer on the planned cutting surface of the ingot. The wafer is peeled off from the ingot along the peeling layer.

[0004] There are irregularities on the peeling surface of the wafer peeled off from the ingot and on the peeling surface of the ingot from which the wafer is peeled off, and these peeling surfaces are typically processed flat with a grinding wheel or a polishing pad. Also, in the processing method described in Patent Document 2, the peeling surfaces of the ingot and the wafer are rubbed against each other to process the peeling surface flat.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] The processing method described in Patent Document 2 can reduce processing costs by suppressing wear on tools such as grinding wheels. However, when the peeled surfaces of the ingot and wafer are rubbed together, the irregularities of the peeled surfaces may interlock, potentially causing damage such as cracks or chips to the wafer.

[0007] The present invention provides a processing method and apparatus capable of suppressing damage to workpieces such as wafers and reducing surface irregularities of workpieces, as well as a method for manufacturing wafers. [Means for solving the problem]

[0008] A processing method according to one aspect of the present invention is a method for processing a workpiece comprising: a holding step of holding a first workpiece in a first holding part and holding a second workpiece made of the same material as the first workpiece in a second holding part; and a surface irregularity reduction step of moving the first workpiece and the second workpiece relatively in the in-plane direction of the contact surface of the first workpiece and the contact surface of the second workpiece while the first workpiece and the second workpiece are in contact with each other, thereby reducing the irregularities of at least one of the contact surfaces of the first workpiece and the second workpiece, wherein in the surface irregularity reduction step, the first workpiece and the second workpiece are brought into contact such that the direction of extension of the irregularities present on the contact surface of the first workpiece and the direction of extension of the irregularities present on the contact surface of the second workpiece intersect.

[0009] Another embodiment of the present invention is a processing apparatus comprising: a first holding part for holding a first workpiece; a second holding part for holding a second workpiece made of the same material as the first workpiece held by the first holding part, facing the first workpiece held by the first holding part; and a moving mechanism for moving the first holding part and the second holding part relative to each other in the in-plane directions of the contact surface of the first workpiece and the contact surface of the second workpiece, while the first workpiece held by the first holding part and the second workpiece held by the second holding part are in contact with each other, wherein the moving mechanism moves the first holding part and the second holding part relative to each other such that a first direction defined in the plane of the contact surface of the first workpiece held by the first holding part and a second direction defined in the plane of the contact surface of the second workpiece held by the second holding part intersect.

[0010] Another embodiment of the present invention is a wafer manufacturing method for manufacturing a wafer having a thickness less than the thickness of the ingot from an ingot, comprising: a delamination layer formation step of forming a delamination layer inside the ingot by positioning the focal point of a laser beam having a wavelength that is transparent to the ingot inside the ingot and scanning the laser beam; a wafer generation step of delaminating the wafer from the ingot starting from the delamination layer; and a surface roughness reduction step of reducing the surface roughness of the delamination surface of the wafer, wherein the surface roughness reduction step involves the delamination surface of the wafer and the delamination surface of the ingot or The wafer is moved relative to the ingot or the other wafer while in contact with the delamination surface of another wafer in which the unevenness reduction step has not been performed, thereby reducing the unevenness of the delamination surface of the wafer, and in the unevenness reduction step, the wafer is moved relative to the ingot or the other wafer while maintaining a state in which a first direction in the delamination surface of the wafer corresponding to the scanning direction of the laser beam intersects with a second direction in the delamination surface of the ingot corresponding to the scanning direction of the laser beam or a second direction in the delamination surface of the other wafer corresponding to the scanning direction of the laser beam. [Effects of the Invention]

[0011] According to the present invention, it is possible to suppress damage to workpieces such as wafers and reduce surface irregularities of the workpiece. [Brief explanation of the drawing]

[0012] [Figure 1] This figure schematically shows an example of a processing apparatus according to Embodiment 1. [Figure 2] This is a schematic plan view showing an example of a workpiece processed by the processing method according to Embodiment 1. [Figure 3] This is a flowchart showing the flow of the processing method according to Embodiment 1. [Figure 4] This figure shows an example of an image of the contact surface of the workpiece acquired during the angle adjustment step in Figure 3. [Figure 5] Figure 3 is a schematic side view showing the state of the workpiece immediately after the start of the surface irregularity reduction step. [Figure 6] Figure 3 is a schematic side view showing the state of the workpiece immediately before the completion of the surface irregularity reduction step. [Figure 7] Figure 3 is a schematic plan view showing the arrangement of the first and second workpieces in the unevenness reduction step, in relation to the direction of extension of the unevenness present on the contact surface. [Figure 8] Figure 3 is a schematic perspective view showing the grinding process of the first workpiece during the grinding step. [Figure 9] Figure 3 is a perspective view of the grinding step in which the second workpiece is being ground. [Figure 10] This flowchart shows a modified example of the processing method shown in Figure 3. [Figure 11] Figure 10 is a schematic perspective view showing the angle adjustment step. [Figure 12] This is a schematic perspective view showing Modification 1 of the relative movement of the first workpiece and the second workpiece in the processing method according to Embodiment 1. [Figure 13]It is a plan view schematically showing a first modification of the relative movement of the first workpiece and the second workpiece in the processing method according to Embodiment 1. [Figure 14] It is a figure schematically showing an example of a processing apparatus for realizing the relative movement of the first workpiece and the second workpiece shown in FIGS. 12 and 13. [Figure 15] It is a perspective view schematically showing a second modification of the relative movement of the first workpiece and the second workpiece in the processing method according to Embodiment 1. [Figure 16] It is a plan view schematically showing a second modification of the relative movement of the first workpiece and the second workpiece in the processing method according to Embodiment 1. [Figure 17] It is a figure schematically showing an example of a processing apparatus for realizing the relative movement of the first workpiece and the second workpiece shown in FIGS. 15 and 16. [Figure 18] It is a plan view of an ingot used in the processing method according to Embodiment 2 and the wafer manufacturing method. [Figure 19] It is a side view of the ingot shown in FIG. 18. [Figure 20] It is a perspective view of a wafer generated by the processing method according to Embodiment 2 and the wafer manufacturing method. [Figure 21] It is a flowchart showing the flow of the processing method according to Embodiment 2 and the wafer manufacturing method. [Figure 22] It is a perspective view schematically showing the peeling layer formation step of FIG. 21. [Figure 23] It is a side view schematically showing the peeling layer formation step of FIG. 21. [Figure 24] It is a perspective view schematically showing the wafer generation step of FIG. 21. [Figure 25] It is a side view schematically showing the unevenness reduction step of FIG. 21. [Figure 26] It is a side view schematically showing a first modification of the processing method according to Embodiment 2. [Figure 27] It is a side view schematically showing a second modification of the processing method according to Embodiment 2.

MODE FOR CARRYING OUT THE INVENTION

[0013] Embodiments for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiments described below. Furthermore, the components described below include those that can be easily imagined by those skilled in the art, and those that are substantially the same. In addition, the components described below can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the present invention.

[0014] [Embodiment 1] A processing apparatus and processing method according to Embodiment 1 of the present invention will be described based on the drawings. Figure 1 is a schematic diagram showing a processing apparatus according to Embodiment 1. The processing apparatus 40 is a device that reduces at least one of the irregularities present on the contact surface 102, which is one surface of the first workpiece 101, and the irregularities present on the contact surface 111, which is one surface of the second workpiece 110. The first workpiece 101 and the second workpiece 110 are made of the same material. The processing apparatus 40 comprises a first holding part 41, a second holding part 50, a moving mechanism 60, and a control unit 100.

[0015] The first holding part 41 holds the back surface 103 of the first workpiece 101, opposite to the contact surface 102, on a holding surface 42 parallel to the horizontal direction. The first holding part 41 is connected to a vacuum suction source (not shown) on the holding surface 42, and the holding surface 42 is sucked by the vacuum suction source, thereby sucking and holding the back surface 103 of the first workpiece 101 placed on the holding surface 42.

[0016] The second holding part 50 holds the second workpiece 110 so that it faces the contact surface 102 of the first workpiece 101 held by the first holding part 41. The second holding part 50 is formed in a disc shape and has a holding surface 51 that holds the contact surface 111 of the second workpiece 110 so that it faces the contact surface 102 of the first workpiece 101 held by the first holding part 41. The holding surface 51 is flat along the horizontal direction. The holding surface 51 of the second holding part 50 is connected to a vacuum suction source (not shown), and the holding surface 51 is sucked by the vacuum suction source, so that the back surface 112 of the second workpiece 110 opposite to the contact surface 111 is sucked and held by the holding surface 51. The second holding part 50 is moved by the moving mechanism 60 while the second workpiece 110 is sucked and held by the holding surface 51.

[0017] Furthermore, a liquid supply nozzle 52 is attached to the second holding part 50. The liquid supply nozzle 52 supplies liquid 53 (for example, pure water) between the first workpiece 101 held in the first holding part 41 and the second workpiece 110 held in the second holding part 50.

[0018] The moving mechanism 60 moves the first holding part 41 and the second holding part 50 relative to each other. The moving mechanism 60 comprises a first moving unit 61, a second moving unit 62, and a pressure sensor 63.

[0019] The first moving unit 61 moves the first holding part 41 and the second holding part 50 relative to each other in a direction parallel to the contact surfaces 102 and 111 (horizontal in Embodiment 1). The first moving unit 61 is positioned above the first holding part 41. In Embodiment 1, the first moving unit 61 moves the moving table 64 holding the second moving unit 62 horizontally. By moving the moving table 64 horizontally, the first moving unit 61 moves the second holding part 50 together with the second moving unit 62 horizontally, from a position where the holding surface 51 of the second holding part 50 is perpendicular to the holding surface 42 of the first holding part 41, to a retracted position where the holding surface 51 is moved away from the holding surface 42 of the first holding part 41.

[0020] The second moving unit 62 moves the first holding part 41 and the second holding part 50 relatively apart or closer together in a direction intersecting the contact surfaces 102, 111 (vertical direction in Embodiment 1). The second moving unit 62 is installed on the moving table 64, and in Embodiment 1, the second holding part 50 is moved vertically, thereby moving the first holding part 41 and the second holding part 50 relatively apart or closer together in a direction intersecting the contact surfaces 102, 111.

[0021] The first moving unit 61 and the second moving unit 62 are equipped with a well-known ball screw that is rotatably mounted around an axis and rotates around the axis to move the moving table 64 horizontally or the second holding part 50 vertically, a well-known motor that rotates the ball screw around an axis, and a well-known guide rail that supports the moving table 64 so as to be movable horizontally or the second holding part 50 vertically.

[0022] The pressure sensor 63 is installed in at least one of the first holding part 41 and the second holding part 50, and measures the pressure generated by pressing the first workpiece 101 held in the first holding part 41 against the second workpiece 110 held in the second holding part 50. The pressure sensor 63 is composed of, for example, a well-known strain gauge, measures information corresponding to the pressure, and outputs the measurement result to the control unit 100.

[0023] In Embodiment 1, a total of three pressure sensors 63 are installed, located between the mounting base 43 on which the first holding part 41 is installed and the first holding part 41, and mounted on each support column 44 that supports the first holding part 41. The position where the pressure sensors 63 are installed is not limited to between the mounting base 43 and the first holding part 41, as long as it is possible to measure information corresponding to the pressure generated by pressing the first workpiece 101 held by the first holding part 41 and the second workpiece 110 held by the second holding part 50 together. The pressure sensors 63 may also be placed between the second moving unit 62 and the second holding part 50, on the second holding part 50, or on the first holding part 41.

[0024] The control unit 100 also controls each component of the processing device 40 to cause the processing device 40 to perform an operation to reduce the unevenness of the contact surfaces 102 and 111. The control unit 100 is a computer having an arithmetic processing unit with a microprocessor such as a CPU (Central Processing Unit), a storage device with memory such as ROM (Read Only Memory) or RAM (Random Access Memory), and an input / output interface device. The arithmetic processing unit of the control unit 100 performs calculations according to the computer program stored in the storage device and outputs control signals for controlling the processing device 40 to each component of the processing device 40 via the input / output interface device.

[0025] The control unit 100 is connected to a display unit, which consists of a liquid crystal display device that displays the status of machining operations and images, and an input unit used by the operator to register machining content information. The input unit consists of a touch panel provided on the display unit.

[0026] Figure 2 is a schematic plan view showing the contact surfaces 102 and 111 of the workpieces 101 and 110. The first workpiece 101 is a disc-shaped or cylindrical workpiece. One surface of the first workpiece 101, the contact surface 102, has irregularities that extend linearly in one direction within the plane of the contact surface 102. In Figure 2, the irregularities of the contact surface 102 are schematically shown by a number of solid lines that are parallel to each other. The second workpiece 110 is also a disc-shaped or cylindrical workpiece, and one surface of the second workpiece 110, the contact surface 111, has irregularities that extend linearly in one direction within the plane of the contact surface 111.

[0027] (Processing method) Figure 3 is a flowchart showing the flow of the processing method according to Embodiment 1. The processing method according to Embodiment 1 is a method of reducing at least one of the irregularities on the contact surface 102 of the first workpiece 101 and the contact surface 111 of the second workpiece 110 by bringing the first workpiece 101 and the second workpiece 110 into contact such that the direction of extension of the irregularities on the contact surface 102 of the first workpiece 101 and the direction of extension of the irregularities on the contact surface 111 of the second workpiece 110 intersect. As shown in Figure 3, the processing method according to Embodiment 1 comprises an angle adjustment step 1002, a holding step 1003, an irregularity reduction step 1004, and a grinding step 1005.

[0028] (Angle adjustment step) The angle adjustment step 1002 sets the orientation angle of the first workpiece 101 when it is placed in the first holding part 41 and the orientation angle of the second workpiece 110 when it is placed in the second holding part 50, such that the direction of extension of the irregularities on the contact surface 102 of the first workpiece 101 intersects with the direction of extension of the irregularities on the contact surface 111 of the second workpiece 110.

[0029] The direction of extension of the irregularities on the contact surfaces 102 and 111 is detected based on an image of the contact surfaces 102 and 111, which is obtained by irradiating the contact surfaces 102 and 111 with light and detecting the reflected light reflected by the contact surfaces 102 and 111. Figure 4 shows an example of an image, in which a striped pattern appears in the image, in which bright and dark lines extending in one direction are repeated in a direction perpendicular to that direction. The direction of extension of the bright and dark lines in the striped pattern corresponds to the direction of extension of the irregularities. Such an image can be obtained, for example, using a white light interferometer, which is widely used for measuring surface roughness.

[0030] The intersection angle between the direction of extension of the irregularities on the contact surface 102 and the direction of extension of the irregularities on the contact surface 111 is, for example, 90°, but is not limited to 90°. At least one of the first workpiece 101 and the second workpiece 110 is rotated so that the intersection angle between the direction of extension of the irregularities on the contact surface 102 and the direction of extension of the irregularities on the contact surface 111 becomes a predetermined angle. Then, the first workpiece 101 and the second workpiece 110 are transported to the first holding unit 41 and the second holding unit 50 by appropriate transport equipment such as a robot arm, while maintaining the set intersection angle.

[0031] (Holding step) The holding step 1003 is the step of holding the first workpiece 101 in the first holding part 41 and the second workpiece 110 in the second holding part 50. In the holding step 1003, the control unit 100 of the processing device 40 controls the moving mechanism 60 to position the second holding part 50 in a retracted position and raise the second holding part 50. In the holding step 1003, the control unit 100 of the processing device 40 controls the first holding part 41 and the second holding part 50 to suction-hold the back surface 103 of the first workpiece 101 to the holding surface 42 of the first holding part 41 and to suction-hold the back surface 112 of the second workpiece 110 to the holding surface 51 of the second holding part 50.

[0032] (Step to reduce unevenness) Figure 5 is a schematic side view showing the state immediately after the start of the unevenness reduction step in Figure 3. Figure 6 is a schematic side view showing the state immediately before the end of the unevenness reduction step in Figure 3. Figure 7 is a schematic plan view showing the arrangement of the first workpiece 101 and the second workpiece 110 in the unevenness reduction step 1004 in Figure 3 in relation to the direction of extension of the irregularities present on the contact surfaces 102 and 111. The unevenness reduction step 1004 is a step in which the first holding part 41 and the second holding part 50 are moved relative to each other while the contact surface 102 of the first workpiece 101 and the contact surface 111 of the second workpiece 110 are in contact, thereby reducing the irregularities on at least one of the contact surfaces 102 and 111 of the first workpiece 101 and the second workpiece 110. In Embodiment 1, the unevenness reduction step 1004 reduces both the unevenness of the contact surface 102 of the first workpiece 101 and the unevenness of the contact surface 111 of the second workpiece 110.

[0033] In the unevenness reduction step 1004, as shown in Figure 5, the control unit 100 of the processing apparatus 40 controls the first moving unit 61 and the second moving unit 62 to bring the contact surface 111 of the second workpiece 110, held by the second holding unit 50, into contact with the contact surface 102 of the first workpiece 101, held by the first holding unit 41. As shown in Figure 7, the first workpiece 101 is positioned such that the direction of extension of the unevenness on the contact surface 102 coincides with the Y direction, which is one horizontal direction. The second workpiece 110 is positioned such that the direction of extension of the unevenness on the contact surface 111 coincides with the X direction, which is one horizontal direction. The contact surfaces 102 and 111 come into contact with each other when the direction of extension of the unevenness on the contact surface 102 and the direction of extension of the unevenness on the contact surface 111 intersect at a 90° angle.

[0034] In the unevenness reduction step 1004, as shown in Figure 5, the control unit 100 of the processing apparatus 40 controls the first moving unit 61 to move the first workpiece 101 and the second workpiece 110 relative to each other for a predetermined time while supplying liquid 53 from the liquid supply nozzle 52 (omitted in Figure 5) with the contact surfaces 102 and 111 of the first workpiece 101 in contact with each other. In Embodiment 1, in the unevenness reduction step 1004, the control unit 100 of the processing apparatus 40 controls the first moving unit 61 to move the second workpiece 110 back and forth in the horizontal direction relative to the first workpiece 101.

[0035] In Embodiment 1, in the unevenness reduction step 1004, the control unit 100 of the processing apparatus 40 adjusts the distance between the first holding part 41 and the second holding part 50 by controlling the second moving unit 62 so that the information corresponding to the pressure measured by the pressure sensor 63 falls within a desired range when the contact surface 102 of the first workpiece 101 and the contact surface 111 of the second workpiece 110 are in contact and moving relative to each other. The desired range is a range that exceeds a predetermined lower limit and falls below a predetermined upper limit. The predetermined lower limit is a value that can reduce the unevenness of the contact surfaces 102 and 111 of the first workpiece 101 and the second workpiece 110, and the predetermined upper limit is a value that causes damage to at least one of the first workpiece 101 and the second workpiece 110. Furthermore, reduction of unevenness means that the surface roughness of the contact surfaces 102 and 111 decreases.

[0036] Thus, in the unevenness reduction step 1004, the control unit 100 of the processing apparatus 40 controls the second moving unit 62 to move the second holding unit 50 away from or closer to the first holding unit 41 so that the information corresponding to the pressure measured by the pressure sensor 63 falls within the desired range, thereby controlling (adjusting) the pressure that presses the first workpiece 101 and the second workpiece 110 against each other.

[0037] As the control unit 100 of the processing apparatus 40 controls the first moving unit 61 to reciprocate the contact surfaces 102 and 111 of the first workpiece 101 and the second workpiece 110 in a relative horizontal direction while keeping them in contact with each other, the irregularities rub against each other and wear down, as shown in Figure 6, and the irregularities gradually decrease. Thus, in the irregularity reduction step 1004, the processing apparatus 40 reduces the irregularities of at least one of the contact surfaces 102 of the first workpiece 101 or the contact surface 111 of the second workpiece 110 by moving them relative to each other using the first moving unit 61 while keeping the contact surfaces 102 of the first workpiece 101 and the contact surface 111 of the second workpiece 110 in contact with each other. In Embodiment 1, the processing apparatus 40 reduces the irregularities of both the contact surface 102 of the first workpiece 101 and the contact surface 111 of the second workpiece 110. Reducing the irregularities of the contact surfaces 102 and 111 means lowering the surface roughness (such as the arithmetic mean roughness) of the contact surfaces 102 and 111.

[0038] In Embodiment 1, during the unevenness reduction step 1004, the control unit 100 of the processing apparatus 40 controls the second moving unit 62 so that the information corresponding to the pressure from the three (all) pressure sensors 63 falls within a desired range.

[0039] (Grinding step) Figure 8 is a schematic perspective view showing the grinding of the first workpiece in the grinding step of Figure 3. Figure 9 is a perspective view showing the grinding of the second workpiece in the grinding step of Figure 3. The grinding step 1005 is a step in which, after the surface reduction step 1004, at least one of the contact surfaces 102, 111 of the first workpiece 101 or the second workpiece 110 is ground with the grinding wheel 124. In Embodiment 1, in the grinding step 1005, both the contact surfaces 102, 111 of the first workpiece 101 and the second workpiece 110 are ground with the grinding wheel 124, but it is sufficient to grind at least one of the contact surfaces 102, 111 with the grinding wheel 124.

[0040] In Embodiment 1, in grinding step 1005, the grinding device 120 holds the back surface 103 of the first workpiece 101 by suction to the holding surface 122 of the chuck table 121. In grinding step 1005, as shown in Figure 8, the grinding device 120 rotates the grinding wheel 124 for grinding around its axis using the spindle 123 and rotates the chuck table 121 around its axis, while supplying grinding fluid from a grinding fluid nozzle (not shown), and brings the grinding wheel 125 of the grinding wheel 124 into contact with the contact surface 102 of the first workpiece 101 and brings it closer to the chuck table 121 at a predetermined feed rate, and grinds the contact surface 102 of the first workpiece 101 with the grinding wheel 125.

[0041] Furthermore, in grinding step 1005, the grinding device 120 holds the back surface 112 of the second workpiece 110 by suction to the holding surface 122 of the chuck table 121. In grinding step 1005, as shown in Figure 9, the grinding device 120 rotates the grinding wheel 124 for grinding around its axis using the spindle 123 and rotates the chuck table 121 around its axis, while supplying grinding fluid from a grinding fluid nozzle (not shown), and brings the grinding wheel 125 of the grinding wheel 124 into contact with the contact surface 111 of the second workpiece 110 and brings it closer to the chuck table 121 at a predetermined feed rate, and grinds the contact surface 111 of the second workpiece 110 with the grinding wheel 125.

[0042] As described above, the processing apparatus 40 and processing method according to Embodiment 1 reduce the irregularities of the contact surfaces 102 and 111 by moving and rubbing the contact surface 102 of the first workpiece 101 and the contact surface 111 of the second workpiece 110 relative to each other while they are in contact. In this way, the processing apparatus 40 and processing method according to Embodiment 1 rub the contact surface 102 of the first workpiece 101 and the contact surface 111 of the second workpiece 110, which are made of the same material, against each other. Therefore, the relatively softer material does not wear down unilaterally, preventing one side from being worn down while the other is worn down, and the grinding power does not decrease. This makes it possible to reduce the irregularities of both the first workpiece 101 and the second workpiece 110.

[0043] The processing apparatus 40 and processing method according to Embodiment 1 move relative to each other and rub against each other while the contact surface 102 of the first workpiece 101 and the contact surface 111 of the second workpiece 110 are in contact. Therefore, the irregularities that would normally be removed by grinding can be utilized to reduce the irregularities, and the wear of the grinding wheel 125 of the grinding wheel 124, which is used to reduce the irregularities, can be suppressed, making it economical. Furthermore, the processing apparatus 40 and processing method according to Embodiment 1 grind the first workpiece 101 and the second workpiece 110 with the grinding wheel 124 while the irregularities are reduced, so the amount of grinding and grinding time can be reduced, and the wear of the grinding wheel 125 of the grinding wheel 124 can be suppressed, making it economical.

[0044] As a result, the processing apparatus 40 and processing method according to Embodiment 1 have the effect of economically reducing the unevenness of at least one of the contact surfaces 102, 111 of the first workpiece 101 or the second workpiece 110, regardless of the workpiece 101, 110, while keeping costs down.

[0045] Furthermore, the processing apparatus 40 and processing method according to Embodiment 1 reduce the irregularities of the workpiece 101, 110 by bringing the materials into contact. This prevents one material from wearing down first and reducing the grinding force, as the materials grind against each other, efficiently reducing the irregularities. Additionally, if the workpiece 101, 110 is made of a hard material, grinding with the grinding wheel 124 increases the wear and cost of the grinding wheel 124. The processing apparatus 40 and processing method according to Embodiment 1 utilize the irregularities to be removed, allowing the materials to grind against each other to reduce the irregularities. This reduces the wear of the grinding wheel 124 compared to grinding the irregularities with the grinding wheel 124, making it more economical. Moreover, because the irregularities grind against each other, the irregularities can be reduced efficiently in a short amount of time.

[0046] Furthermore, in the processing apparatus 40 and processing method according to Embodiment 1, the direction of extension of the irregularities on the contact surface 102 of the first workpiece 101 and the direction of extension of the irregularities on the contact surface 111 of the second workpiece 110 intersect with each other, thereby preventing the irregularities from catching on each other. This reduces the possibility of damage such as cracks or chips occurring in the first workpiece 101 and the second workpiece 110.

[0047] In the machining method shown in Figure 3, the angle adjustment step 1002 is performed before the holding step 1003, but as shown in Figure 10, the angle adjustment step 1002 may be performed after the holding step 1003. When the angle adjustment step 1002 is performed after the holding step 1003, as shown in Figure 11, with the first workpiece 101 held in the first holding part 41 and the second workpiece 110 held in the second holding part 50, the imaging device 70 acquires images of the contact surface 102 of the first workpiece 101 and the contact surface 111 of the second workpiece 110, and the direction of extension of the irregularities on the contact surface 102 and the contact surface 111 are detected. Then, at least one of the first holding part 41 and the second holding part 50 is rotated so that the intersection angle between the direction of extension of the irregularities on the contact surface 102 and the direction of extension of the irregularities on the contact surface 111 becomes a predetermined angle.

[0048] [Modified example of Embodiment 1] Other examples of the relative movement of the second workpiece 110 with respect to the first workpiece 101 in the unevenness reduction step 1004 are described below. Figure 12 is a schematic perspective view showing the relative movement of Modification 1, and Figure 13 is a schematic plan view showing the relative movement of Modification 1. Figure 14 is a schematic diagram showing an example of the configuration of the processing apparatus used for the relative movement of Modification 1. Figure 15 is a schematic perspective view showing the relative movement of Modification 2, and Figure 16 is a schematic plan view showing the relative movement of Modification 2. Figure 17 is a schematic diagram showing an example of the configuration of the processing apparatus used for the relative movement of Modification 2.

[0049] In the modified example 1 shown in Figures 12 and 13, the first workpiece 101 is positioned such that the direction of extension of the irregularities on the contact surface 102 coincides with the Y direction. The second workpiece 110 is positioned such that the direction of extension of the irregularities on the contact surface 111 coincides with the X direction. Furthermore, the first workpiece 101 and the second workpiece 110 are positioned such that the center O1 of the contact surface 102 and the center O2 of the contact surface 111 are offset horizontally. The center-to-center distance D between the center O1 of the contact surface 102 and the center O2 of the contact surface 111 is set to be less than the radius of the circular first workpiece 101 and the second workpiece 110. In other words, the center-to-center distance D is set such that the center O1 of the contact surface 102 coincides with the contact surface 111, and the center O2 of the contact surface 111 coincides with the contact surface 102.

[0050] The second workpiece 110 is then moved circumferentially relative to the first workpiece 101 along a circle C centered at the center O1 of the contact surface 102 of the first workpiece 101 and with radius D being the distance between the centers. During this time, the direction of extension of the irregularities on the contact surface 102 of the first workpiece 101 is fixed in the Y direction, and the direction of extension of the irregularities on the contact surface 111 of the second workpiece 110 is fixed in the X direction. As a result, with the contact surfaces 102 and 111 in contact with each other, the intersection angle between the direction of extension of the irregularities on the contact surface 102 and the direction of extension of the irregularities on the contact surface 111 is maintained at 90°, causing the irregularities on the contact surfaces 102 and 111 to rub against each other and wear down.

[0051] The relative movement of the first workpiece 101 and the second workpiece 110 in Modification 1 is achieved, for example, by a processing apparatus 40A equipped with a third moving unit 65, as shown in Figure 14. The processing apparatus 40A is identical to the processing apparatus 40 in Figure 1, except that it is equipped with a third moving unit 65. The first moving unit 61 moves the second moving unit 62 in the X direction, which is one horizontal direction, while the third moving unit 65 moves the first moving unit 61 in the Y direction, which is one horizontal direction and perpendicular to the X direction. The third moving unit 65 is equipped with a ball screw, a motor, and a guide rail, similar to the first moving unit 61 and the second moving unit 62.

[0052] In the modified example 2 shown in Figures 15 and 16, similar to the modified example 1, the first workpiece 101 is positioned such that the direction of extension of the irregularities on the contact surface 102 coincides with the Y direction. The second workpiece 110 is positioned such that the direction of extension of the irregularities on the contact surface 111 coincides with the X direction. Furthermore, the first workpiece 101 and the second workpiece 110 are positioned such that the center O1 of the contact surface 102 and the center O2 of the contact surface 111 are offset horizontally. The center-to-center distance D between the center O1 of the contact surface 102 and the center O2 of the contact surface 111 is set to be less than the radius of the circular first workpiece 101 and the second workpiece 110.

[0053] Then, the first workpiece 101 is rotated around the center O1 of the contact surface 102, and the second workpiece 110 is rotated around the center O2 of the contact surface 111 in the same direction and at the same speed as the first workpiece 101. As a result, with the contact surfaces 102 and 111 in contact with each other, the intersection angle between the direction of extension of the irregularities on the contact surface 102 and the direction of extension of the irregularities on the contact surface 111 is maintained at 90°, and the irregularities on the contact surfaces 102 and 111 rub against each other and wear down.

[0054] The relative movement of the first workpiece 101 and the second workpiece 110 in Modification 2 is achieved by a machining apparatus 40B equipped with a rotary drive source 54 and a rotary drive source 55, as shown in Figure 17, for example. The machining apparatus 40B is identical to the machining apparatus 40 in Figure 1, except that it is equipped with a rotary drive source 54 and a rotary drive source 55. The rotary drive source 54 rotates the first holding part 41 around an axis parallel to the vertical direction. The rotary drive source 55 rotates the second holding part 50 around an axis parallel to the vertical direction.

[0055] According to Modification 1 and Modification 2, the direction of extension of the irregularities on the contact surface 102 and the direction of extension of the irregularities on the contact surface 111 intersect with each other, preventing the irregularities from catching on each other and reducing the possibility of damage such as cracks or chips occurring in the first workpiece 101 and the second workpiece 110. Furthermore, the wear of the irregularities is accelerated because they rub against each other in circular motion instead of translational motion. This makes it possible to reduce the irregularities efficiently. Moreover, in Modification 2, the position of the first workpiece 101 and the second workpiece 110 can be fixed while performing the irregularity reduction step, which also contributes to miniaturization of the processing equipment.

[0056] [Embodiment 2] A processing method and wafer manufacturing method according to Embodiment 2 of the present invention will be described based on the drawings. Figure 18 is a plan view of an ingot used in the processing method and wafer manufacturing method according to Embodiment 2. Figure 19 is a side view of the ingot shown in Figure 18. Figure 20 is a perspective view of a wafer produced by the processing method and wafer manufacturing method according to Embodiment 2. In the description of Embodiment 2, the same parts as in Embodiment 1 will be denoted by the same reference numerals.

[0057] (Ingots and wafers) Figure 18 is a plan view of an ingot, which is an example of the first workpiece 101. Figure 19 is a side view of the ingot shown in Figure 18. Figure 20 is a perspective view of a wafer, which is an example of the second workpiece 110.

[0058] Ingot 1, shown in Figure 18, is formed in a cylindrical shape overall and is a hexagonal single crystal SiC (silicon carbide) ingot. Ingot 1 may also be composed of Ge (germanium), GaAs (gallium arsenide), or Si (silicon).

[0059] As shown in Figures 18 and 19, ingot 1 has a circularly formed exfoliation surface 11 (corresponding to the contact surface), a circularly formed second surface 3 (corresponding to the back surface) on the opposite side of the exfoliation surface 11, and a circumferential surface 4 that extends from the outer edge of the exfoliation surface 11 to the outer edge of the second surface 3. In addition, ingot 1 has a linear first orientation flat 5 indicating the crystal orientation on the circumferential surface 4, and a linear second orientation flat 6 perpendicular to the first orientation flat 5. The length of the first orientation flat 5 is longer than the length of the second orientation flat 6.

[0060] Ingot 1 is formed by rough grinding and finish grinding of the peeled surface 11 by a grinding device, followed by polishing by a polishing device to form a mirror-like first surface 2 (corresponding to the end surface, shown in Figure 20). Ingot 1 also has a c-axis 9 inclined at an off-angle α in the inclination direction 8 toward the second orientation flat 6 with respect to the perpendicular 7 of the first surface 2, and a c-face 10 perpendicular to the c-axis 9. The c-face 10 is inclined at an off-angle α with respect to the first surface 2 of ingot 1. The inclination direction 8 of the c-axis 9 from the perpendicular 7 is perpendicular to the elongation direction of the second orientation flat 6 and parallel to the first orientation flat 5. The c-face 10 is set infinitely many times within ingot 1 at the molecular level. In Embodiment 2, the off-angle α is set to 1°, 4°, or 6°, but ingot 1 can be manufactured by freely setting the off-angle α in the range of, for example, 1° to 6°.

[0061] A portion of the ingot 1 on the first surface 2 side is peeled off, and the peeled portion becomes the wafer 20 shown in Figure 20. For this reason, the wafer 20 is peeled off sequentially from the first surface 2 side of the ingot 1, and the thickness decreases. That is, after the wafer 20, which is the second workpiece, is peeled off, the ingot 1 has a peeled surface 11, which is the surface from which the wafer 20 was peeled off, and a second surface 3. After the wafer 20, which is the second workpiece, is peeled off, the peeled surface 11 of the ingot 1 is polished to a mirror finish and formed on the first surface 2, after which the next wafer 20 is peeled off. Hereafter, the ingot 1 with the peeled surface 11 polished to a mirror finish and formed on the first surface 2 is indicated by reference numeral 1-1.

[0062] The wafer 20 shown in Figure 20 is obtained by peeling off a portion of the ingot 1-1, including the first surface 2. Therefore, the wafer 20 has the first surface 2 and a peeled surface 21 (corresponding to the contact surface), which is the surface peeled off from the ingot 1-1. For this reason, the wafer 20 is made of the same material as the ingot 1. After the peeled surface 21 of the wafer 20 is roughly ground and finish ground by a grinding device, and then polished by a polishing device, a device is formed in the region of the surface that is divided into a grid pattern by multiple planned division lines.

[0063] The device is a MOSFET (Metal-oxide-semiconductor Field-effect Transistor), MEMS (Micro Electro Mechanical Systems), or SBD (Schottky Barrier Diode), but is not limited to MOSFETs, MEMS, and SBDs. Note that the same reference numerals are used for parts of wafer 20 that are the same as those of ingot 1, and their descriptions are omitted.

[0064] Figure 21 is a flowchart showing a method for producing a wafer 20 by peeling off a portion of an ingot 1-1 having a mirror-like first surface 2 as the wafer 20 to be produced. The method for producing the wafer 20 comprises a peeling layer formation step 1000 and a wafer production step 1001, as shown in Figure 21.

[0065] (Exfoliation layer formation step) Figure 22 is a schematic perspective view showing the delamination layer formation step of Figure 21. Figure 23 is a schematic side view showing the delamination layer formation step of Figure 21. The delamination layer formation step 1000 is a step in which the focal point 35 of a laser beam 34 with a wavelength that is transparent to the ingot 1-1 having a first surface 2 is positioned at a depth 36 corresponding to the thickness 22 (shown in Figure 20) of the wafer 20 generated from the first surface 2 of the ingot 1-1, and the laser beam 34 is irradiated onto the ingot 1-1 to form a delamination layer 37 that separates the first surface 2 and the second surface 3 of the ingot 1 from the wafer 20 that extends in a direction parallel to it.

[0066] In the delamination layer formation step 1000, the wafer production apparatus 30 holds the second surface 3 of the ingot 1-1 by suction to the holding surface 32 of the holding table 31. In the delamination layer formation step 1000, the wafer production apparatus 30 controls the laser beam irradiation unit 33 to position the focal point 35 of a pulsed laser beam 34 with a wavelength that is transparent to the ingot 1-1 at a depth 36 corresponding to the thickness 22 of the wafer 20 to be manufactured from the first surface 2 of the ingot 1-1, and irradiates the wafer with the laser beam irradiation unit 33 and the holding table 31 while moving them relative to each other in the X-axis direction parallel to the horizontal direction. In Embodiment 2, the X-axis direction and the second orientation flat 6 are positioned parallel to each other.

[0067] When the laser beam 34 is irradiated onto the ingot 1-1, a modified region is formed along the X-axis direction at a depth 36 from the first surface 2 inside the ingot, because the laser beam 34 has a wavelength that is penetrating to the ingot 1-1. Cracks are generated extending from the modified region along the c-plane 10. The modified region is formed when SiC is separated into Si (silicon) and C (carbon) by irradiation with a pulsed laser beam 34, and the next pulsed laser beam 34 is absorbed by the previously formed C, causing a chain reaction of separation of SiC into Si and C. The modified region refers to an area where the density, refractive index, mechanical strength, and other physical properties are different from those of the surrounding area. Examples include a melted region, a cracked region, a dielectric breakdown region, a refractive index change region, and a region where these regions are mixed. The modified region has lower mechanical strength, etc., than other parts of the ingot 1-1. Thus, when ingot 1-1 is irradiated with a pulsed laser beam 34 having a wavelength that is penetrating to ingot 1-1, a delamination layer 37 is formed, which includes a modified portion and cracks formed along the c-plane 10 from the modified portion.

[0068] In the delamination layer formation step 1000, the wafer production apparatus 30 forms a delamination layer 37 along the entire length of the second orientation flat 6 of the ingot 1-1. Then, it temporarily stops the irradiation of the laser beam 34 from the laser beam irradiation unit 33 and moves the laser beam irradiation unit 33 and the holding table 31 relatively a predetermined distance 29 (shown in Figure 22) along the horizontal direction and the Y-axis direction perpendicular to the X-axis direction (hereinafter referred to as index feed). In the delamination layer formation step 1000, after the index feed, the wafer production apparatus 30 positions the focal point 35 of the laser beam 34 at the depth 36 described above, and irradiates the laser beam 34 while moving the laser beam irradiation unit 33 and the holding table 31 relatively in the X-axis direction to form the delamination layer 37.

[0069] In the delamination layer formation step 1000, the wafer production apparatus 30 alternately irradiates the wafer with a laser beam 34 while moving the laser beam irradiation unit 33 and the holding table 31 relative to each other along the X-axis, and feeds the wafer with an index, repeating this until a delamination layer 37 is formed over the entire area below the first surface 2 of the ingot 1-1.

[0070] (Wafer generation step) Figure 24 is a schematic perspective view showing the wafer production step in Figure 21. The wafer production step 1001 is a step in which, after performing the delamination layer formation step 1000, the wafer 20 to be produced is peeled off from the ingot 1-1 starting from the delamination layer 37 to produce the wafer 20.

[0071] In wafer production step 1001, the wafer production apparatus 30 holds the second surface 3 of the ingot 1-1, on the holding surface 26 of the second holding table 25 by suction, after the delamination layer 37 has been formed. The wafer production apparatus 30 also retracts the laser beam irradiation unit 33 from above the second surface 3 of the ingot 1-1 held on the second holding table 25. Then, as shown in Figure 24, the wafer production apparatus 30 holds the first surface 2 of the ingot 1-1 by suction, on the suction surface 39 which is the lower surface of the holding part 38. While supplying liquid to the delamination layer 37 by a liquid supply means (not shown), the wafer production apparatus 30 applies alternating current power for a predetermined time to the ultrasonic transducer in the holding part 38 that holds the first surface 2 of the ingot 1-1 by suction, causing the holding part 38 to vibrate ultrasonically.

[0072] In wafer production step 1001, the wafer production apparatus 30 vibrates the holding unit 38 ultrasonically, transmitting this ultrasonic vibration to the first surface 2 of the ingot 1-1, thereby applying ultrasonic vibration. This ultrasonic vibration stimulates the delamination layer 37, splitting the ingot 1-1 starting from the delamination layer 37, and separating the wafer 20 to be produced from the ingot 1-1.

[0073] In the wafer production step 1001, the wafer production apparatus 30 applies alternating current power to the ultrasonic transducer of the holding unit 38 for a predetermined time to cause the holding unit 38 to vibrate ultrasonically, and when the wafer 20 to be produced is separated from the ingot 1-1, the application of alternating current power to the ultrasonic transducer is stopped, the holding unit 38 is moved away from above the second holding table 25, and the wafer 20 is peeled off from the ingot 1-1. Various methods can be used as long as the wafer 20 can be peeled off from the ingot 1-1 starting from the peeling layer 37. For example, the wafer may be peeled off by applying ultrasonic vibration while the ingot 1-1 is placed in a water tank, or it may be peeled off without using ultrasonic vibration.

[0074] Thus, the first surface 2 side is peeled off as a wafer 20 starting from the peeling layer 37, forming an ingot 1 having a peeled surface 11 (corresponding to a contact surface) and a wafer 20 having a peeled surface 21 (corresponding to a contact surface). The peeled surface 11 of the ingot 1 is the surface from which the wafer 20 was peeled off in the wafer production step 1001, and the peeled surface 21 of the wafer 20 is the surface peeled off from the ingot 1 in the wafer production step 1001. The peeled surfaces 11 and 21 formed by the peeling layer 37 have irregularities that extend linearly in one direction within the surface, and the direction of extension of the irregularities corresponds to the scanning direction of the laser beam 34 in the peeling layer formation step 1000 (the X-axis direction in Figure 22). Therefore, the direction of extension of the irregularities on the peeled surfaces 11 and 21 is perpendicular to the first orientation flat 5 and parallel to the second orientation flat 6.

[0075] (Angle adjustment step) The angle adjustment step 1002 sets the orientation angle of the ingot 1 when it is placed in the first holding part 41 of the processing apparatus 40, and the orientation angle of the wafer 20 when it is placed in the second holding part 50 of the processing apparatus 40, so that the direction of extension of the irregularities on the peeling surface 11 of the ingot 1 intersects with the direction of extension of the irregularities on the peeling surface 21 of the wafer 20. The direction of extension of the irregularities on the peeling surfaces 11 and 21 can be detected based on the striped pattern that appears in the captured image of the peeling surfaces 11 and 21, similar to the processing method of Embodiment 1. Alternatively, the direction of extension of the irregularities on the peeling surfaces 11 and 21 can also be detected based on the outer circumferential shapes of the ingot 1 and wafer 20.

[0076] As described above, the direction of extension of the irregularities on the peeling surfaces 11 and 21 is perpendicular to the relatively long first orientation flat 5 and parallel to the relatively short second orientation flat 6. Therefore, the direction of extension of the irregularities on the peeling surfaces 11 and 21 can be detected by detecting the first orientation flat 5 and / or the second orientation flat 6 from the captured images of the ingot 1 and wafer 20. At least one of the ingot 1 and wafer 20 is rotated so that the intersection angle between the direction of extension of the irregularities on the peeling surface 11 and the direction of extension of the irregularities on the peeling surface 21 is a predetermined angle. Then, the ingot 1 and wafer 20 are transported to the first holding unit 41 and the second holding unit 50 by appropriate transport equipment such as a robot arm while maintaining the set intersection angle.

[0077] (Holding step) The holding step 1003 is the step of holding the ingot 1 from which the wafer 20 has been detached in the first holding part 41, and holding the wafer 20 detached from the ingot 1 in the second holding part 50. In the holding step 1003, the control unit 100 of the processing apparatus 40 controls the moving mechanism 60 to position the second holding part 50 in a retracted position and raise the second holding part 50. In the holding step 1003, the control unit 100 of the processing apparatus 40 controls the first holding part 41 and the second holding part 50 to suction-hold the second surface 3 of the ingot 1 to the holding surface 42 of the first holding part 41, and to suction-hold the first surface 2 of the wafer 20 to the holding surface 51 of the second holding part 50. Thus, in Embodiment 2, the first workpiece, ingot 1, is the ingot from which the wafer 20 was peeled off in the wafer production step 1001, and the second workpiece, wafer 20, is the wafer produced in the wafer production step 1001.

[0078] (Step to reduce unevenness) The unevenness reduction step 1004 is a step in which the first holding part 41 and the second holding part 50 are moved relative to each other while the peeled surface 11 of the ingot 1 from which the wafer 20 has been peeled and the peeled surface 21 of the wafer 20 peeled from the ingot 1 are in contact, thereby reducing the unevenness of at least one of the peeled surfaces 11, 21 of the ingot 1 and the wafer 20. In Embodiment 2, the unevenness reduction step 1004 is a step in which both the unevenness of the peeled surface 11 of the ingot 1 and the unevenness of the peeled surface 21 of the wafer 20 are reduced.

[0079] In the unevenness reduction step 1004, as shown in Figure 25, the control unit 100 of the processing apparatus 40 controls the first moving unit 61 and the second moving unit 62 to bring the peeled surface 21 of the wafer 20 held in the second holding unit 50 into contact with the peeled surface 11 of the ingot 1 held in the first holding unit 41. The peeled surfaces 11 and 21 come into contact with each other when the direction of extension of the unevenness of the peeled surface 11 and the direction of extension of the unevenness of the peeled surface 21 intersect at a predetermined angle set in the angle adjustment step 1002.

[0080] In the unevenness reduction step 1004, as shown in Figure 1, the control unit 100 of the processing apparatus 40 controls the first moving unit 61 to move the ingot 1 and the wafer 20 relative to each other for a predetermined time while supplying liquid 53 from the liquid supply nozzle 52, with the peeled surfaces 11 and 21 of the ingot 1 and the wafer 20 in contact with each other. In Embodiment 2, in the unevenness reduction step 1004, the control unit 100 of the processing apparatus 40 controls the first moving unit 61 to reciprocate the wafer 20 in a horizontal direction relative to the ingot 1.

[0081] In Embodiment 2, in the unevenness reduction step 1004, the control unit 100 of the processing apparatus 40 adjusts the distance between the first holding part 41 and the second holding part 50 by controlling the second moving unit 62 so that the information corresponding to the pressure measured by the pressure sensor 63 falls within a desired range when the peeling surface 11 of the ingot 1 and the peeling surface 21 of the wafer 20 are in contact and moving relative to each other. The desired range is a range that exceeds a predetermined lower limit and falls below a predetermined upper limit. The predetermined lower limit is a value that can reduce the unevenness of the peeling surfaces 11 and 21 of the ingot 1 and wafer 20, and the predetermined upper limit is a value that causes damage to at least one of the wafer 20 and the ingot 1. Furthermore, reduction of unevenness means that the surface roughness of the peeling surfaces 11 and 21 decreases.

[0082] Thus, in the unevenness reduction step 1004, the control unit 100 of the processing apparatus 40 controls the second moving unit 62 to move the second holding unit 50 away from or closer to the first holding unit 41, so that the information corresponding to the pressure measured by the pressure sensor 63 falls within the desired range, thereby controlling (adjusting) the pressure that presses the ingot 1 and the wafer 20 against each other.

[0083] In the unevenness reduction step 1004, the control unit 100 of the processing apparatus 40 controls the first moving unit 61 to reciprocate relatively horizontally while the peeled surface 11 of the ingot 1 and the peeled surface 21 of the wafer 20 are in contact with each other. As a result, the unevenness rubs against each other and wears down, gradually reducing the unevenness. Thus, in the unevenness reduction step 1004, the processing apparatus 40 reduces the unevenness of at least one of the peeled surface 11 of the ingot 1 or the peeled surface 21 of the wafer 20 by moving them relatively with the first moving unit 61 while they are in contact with each other. In Embodiment 2, the processing apparatus 40 reduces the unevenness of both the peeled surface 11 of the ingot 1 and the peeled surface 21 of the wafer 20. Reducing the irregularities of the peeling surfaces 11 and 21 means lowering the surface roughness (such as the arithmetic mean roughness) of the peeling surfaces 11 and 21.

[0084] In Embodiment 2, during the unevenness reduction step 1004, the control unit 100 of the processing apparatus 40 controls the second moving unit 62 so that the information corresponding to the pressure from the three (all) pressure sensors 63 falls within a desired range.

[0085] (Grinding step) The grinding step 1005 is a step in which, after the unevenness reduction step 1004, at least one of the delamination surfaces 11, 21 of the ingot 1 or wafer 20 is ground with the grinding wheel 124. In Embodiment 2, in grinding step 1005, both the delamination surfaces 11, 21 of the ingot 1 and wafer 20 are ground with the grinding wheel 124, but in the present invention, it is sufficient to grind at least one of the delamination surfaces 11, 21 with the grinding wheel 124.

[0086] In Embodiment 2, in grinding step 1005, the grinding device 120 holds the second surface 3 of the ingot 1 by suction to the holding surface 122 of the chuck table 121. In grinding step 1005, as shown in Figure 8, the grinding device 120 rotates the grinding wheel 124 for grinding around its axis using the spindle 123 and rotates the chuck table 121 around its axis, while supplying grinding fluid from a grinding fluid nozzle (not shown), and brings the grinding wheel 125 of the grinding wheel 124 into contact with the peeled surface 11 of the ingot 1 and approaches the chuck table 121 at a predetermined feed rate, thereby grinding the peeled surface 11 of the ingot 1 with the grinding wheel 125.

[0087] In the grinding step 1005, a surface protection tape 23 is attached to the first surface 2 of the wafer 20, and the grinding device 120 holds the first surface 2 of the wafer 20 to the holding surface 122 of the chuck table 121 by suction via the surface protection tape 23. In the grinding step 1005, as shown in Figure 9, the grinding device 120 rotates the grinding wheel 124 for grinding around its axis using the spindle 123 and rotates the chuck table 121 around its axis, while supplying grinding fluid from a grinding fluid nozzle (not shown), and brings the grinding wheel 125 of the grinding wheel 124 into contact with the peeled surface 21 of the wafer 20 and approaches the chuck table 121 at a predetermined feed rate, thereby grinding the peeled surface 21 of the wafer 20 with the grinding wheel 125.

[0088] Subsequently, the peeled surface 11 of ingot 1 is finished grinding and polished to form the first surface 2. Then, the wafer 20 of ingot 1-1 is peeled off again from the first surface 2 side. In this way, the thickness of ingot 1,1-1 decreases as the wafer 20 is peeled off, and a peeled layer 37 is formed until a predetermined thickness is reached, and a portion is peeled off as wafer 20. Furthermore, the peeled surface 21 of wafer 20 is finished grinding and polished, and a device is formed on its surface.

[0089] The processing method and wafer manufacturing method according to Embodiment 2 reduce the irregularities of the peeled surfaces 11 and 21 by moving and rubbing the peeled surface 11 of the ingot 1 and the peeled surface 21 of the wafer 20 relative to each other while they are in contact. In this way, the processing apparatus 40 and irregularity reduction method according to Embodiment 2 rub the peeled surface 11 of the ingot 1 and the peeled surface 21 of the wafer 20, which are made of the same material, against each other. This prevents the relatively softer material from wearing down unilaterally, avoiding wear on only one side or a decrease in grinding power, and thus reduces the irregularities of both the ingot 1 and the wafer 20.

[0090] In the processing method and wafer manufacturing method according to Embodiment 2, the peeled surface 11 of the ingot 1 and the peeled surface 21 of the wafer 20 are brought into contact with each other and moved relative to each other and rubbed against one another. This reduces the unevenness that would normally be removed by grinding, thus suppressing the wear of the grinding wheel 125 of the grinding wheel 124 used to reduce unevenness, making it economical. Furthermore, in the processing method and wafer manufacturing method according to Embodiment 2, the ingot 1 and wafer 20 are ground with the grinding wheel 124 while the unevenness is reduced, thus reducing the amount of material removed and the grinding time, and suppressing the wear of the grinding wheel 125 of the grinding wheel 124, making it economical.

[0091] As a result, the processing method and wafer manufacturing method according to Embodiment 2 have the effect of economically reducing the unevenness of at least one of the peeled surfaces, either the peeled surface 11 of the ingot 1 or the peeled surface 21 of the wafer 20.

[0092] In particular, the processing method and wafer manufacturing method according to Embodiment 2 have the effect of further suppressing the wear of the grinding wheel 125 of the grinding wheel 124 and economically reducing the unevenness of the peeled surfaces 11 and 21, since the ingot 1 and wafer 20 are made of SiC, which is harder than Si.

[0093] Furthermore, the processing method and wafer manufacturing method according to Embodiment 2 reduce the irregularities of the ingot 1 and wafer 20 by bringing the materials into contact. This prevents one material from wearing down first and reducing the grinding power, as they mutually grind against each other, efficiently reducing the irregularities. Additionally, if the ingot 1 and wafer 20 are made of hard materials, grinding with the grinding wheel 124 increases the wear and cost of the grinding wheel 124. In the present invention, the irregularities to be removed are utilized to reduce the irregularities by grinding against each other within the same material. This reduces the wear of the grinding wheel 124 compared to grinding the irregularities with the grinding wheel 124, making it more economical. Moreover, because the irregularities grind against each other, the irregularities can be reduced efficiently in a short amount of time.

[0094] Furthermore, in the processing method and wafer manufacturing method according to Embodiment 2, the direction of extension of the irregularities on the peeled surface 11 of the ingot 1 and the direction of extension of the irregularities on the peeled surface 21 of the wafer 20 intersect with each other, thereby preventing the irregularities from catching on each other. This reduces the possibility of damage such as cracks or chips occurring in the ingot 1 and wafer 20.

[0095] In Embodiment 2, the holding table 31 used in the peeling layer formation step 1000, the second holding table 25 used in the wafer generation step 1001, and the first holding part 41 used in the unevenness reduction step 1004 are all separate entities. Also, the holding part 38 used in the wafer generation step 1001 and the second holding part 50 are all separate entities. However, the holding table 31 used in the peeling layer formation step 1000 and the second holding table 25 used to hold the ingot 1 in the wafer generation step 1001 may be used interchangeably as the first holding part 41 in the unevenness reduction step 1004, and the holding part 38 used to hold the peeled wafer 20 in the wafer generation step 1001 may be used interchangeably as the second holding part 50 in the unevenness reduction step 1004. In this case, the apparatus used in the unevenness reduction method according to Embodiment 2 can be miniaturized. Furthermore, since the direction of extension of the irregularities present on the delamination surface 11 of the ingot 1 and the delamination surface 21 of the wafer 20 corresponds to the scanning direction of the laser beam 34 in the delamination layer formation step 1000 (the X-axis direction in Figure 22), the detection of the direction of extension of the irregularities in the angle adjustment step 1002 can be omitted, thereby simplifying the manufacturing process.

[0096] Furthermore, in the processing method shown in Figure 21, the angle adjustment step 1002 is performed before the holding step 1003, but the angle adjustment step 1002 may also be performed after the holding step 1003. When the angle adjustment step 1002 is performed after the holding step 1003, with the ingot 1 held in the first holding part 41 and the wafer 20 held in the second holding part 50, at least one of the first holding part 41 and the second holding part 50 is rotated so that the intersection angle between the direction of extension of the irregularities on the peeled surface 11 of the ingot 1 and the direction of extension of the irregularities on the peeled surface 21 of the wafer 20 becomes a predetermined angle.

[0097] Furthermore, the relative movement of the ingot 1 and wafer 20 in the unevenness reduction step 1004 may be circular motion along a circle C centered at the center O1 of the peeling surface 11 of the ingot 1 and having a radius less than the radius of the ingot 1 and wafer 20, similar to Modification 1 of Embodiment 1 shown in Figures 12 and 13, or it may be circular motion in which the ingot 1 and wafer 20 rotate in the same direction and at the same speed, similar to Modification 2 of Embodiment 1 shown in Figures 15 and 16.

[0098] [Modified version of Embodiment 2] Figure 26 is a schematic side view showing modification 1 of the processing method according to Embodiment 2. Figure 27 is a schematic side view showing modification 2 of the processing method according to Embodiment 2. In Figures 26 and 27, the same reference numerals are used for parts that are the same as those in Embodiment 1, and their descriptions are omitted.

[0099] In the modified example 1, in the holding step 1003, the processing device 40 holds the second surface 3 of the ingot 1 by suction against the holding surface 42 of the first holding part 41, and holds the second surface 3 of the ingot 1 by suction against the holding surface 51 of the second holding part 50. That is, both the first workpiece and the second workpiece are ingots 1. Then, in the unevenness reduction step 1004, as shown in Figure 26, the processing device 40 brings the peeled surfaces 11 of these ingots 1 into contact with each other and moves the second holding part 50 horizontally, thereby moving the ingot 1 held by the first holding part 41 and the ingot 1 held by the second holding part 50 relative to each other. The relative movement of the other ingot 1 with respect to the other ingot 1 may be circular motion along a circle C centered at the center O1 of the peeling surface 11 of the one ingot 1 and having a radius less than the radius of the ingot 1, as in the modified example 1 of Embodiment 1 shown in Figures 12 and 13, or it may be circular motion in which the one ingot 1 and the other ingot 1 rotate in the same direction and at the same speed, as in the modified example 2 of Embodiment 1 shown in Figures 15 and 16.

[0100] Furthermore, in the modified example 2, in the holding step 1003, the processing apparatus 40 suction-holds the first surface 2 of the wafer 20 to the holding surface 42 of the first holding part 41, and suction-holds the first surface 2 of the wafer 20 to the holding surface 51 of the second holding part 50. That is, both the first workpiece and the second workpiece are wafers 20. Then, in the unevenness reduction step 1004, as shown in Figure 27, the processing apparatus 40 brings the peeled surfaces 21 of these wafers 20 into contact with each other and moves the second holding part 50 horizontally, thereby moving the wafer 20 held by the first holding part 41 and the wafer 20 held by the second holding part 50 relative to each other. The relative movement of one wafer 20 to the other wafer 20 may be circular motion along a circle C centered at the center O1 of the delamination surface 21 of one wafer 20 and having a radius less than the wafer radius, similar to Modification 1 of Embodiment 1 shown in Figures 12 and 13, or it may be circular motion in which one wafer 20 and the other wafer 20 rotate in the same direction and at the same speed, similar to Modification 2 of Embodiment 1 shown in Figures 15 and 16.

[0101] As described above, the unevenness reduction step 1004 of the processing method according to Embodiment 2 reduces the unevenness of the peeling surface 11 of the ingot 1 and the peeling surface 21 of the wafer 20 by moving them relatively while the contact surfaces of the first workpiece and the second workpiece (the peeling surface 11 of the ingot 1 and the peeling surface 21 of the wafer 20) are in contact with each other, by using any combination of the first workpiece and the second workpiece as ingot 1 and ingot 1, wafer 20 and wafer 20, and setting them in contact with each other.

[0102] It should be noted that the present invention is not limited to the embodiments described above. That is, it can be implemented with various modifications without departing from the core of the present invention. For example, in Embodiment 2 described above, the unevenness reduction step 1004 was described as reducing the unevenness of the peeling surfaces 11, 21 of both the first workpiece, which is the ingot 1 or wafer 20, and the second workpiece, which is the ingot 1 or wafer 20. However, it is sufficient to reduce the unevenness of at least one of the contact surfaces 102, 111 of the first workpiece 101 and the second workpiece 110.

[0103] This specification contains at least the following: (1) A holding step in which a first workpiece is held in a first holding part, and a second workpiece made of the same material as the first workpiece is held in a second holding part, A surface irregularity reduction step is performed by moving the first workpiece and the second workpiece relative to each other in the in-plane direction of the contact surface of the first workpiece and the contact surface of the second workpiece while the first workpiece and the second workpiece are in contact, thereby reducing the irregularities of the contact surface of the first workpiece and at least one of the contact surfaces of the second workpiece. A method for processing a workpiece, comprising: A machining method in which, in the unevenness reduction step, the first workpiece and the second workpiece are brought into contact such that the direction of extension of the unevenness present on the contact surface of the first workpiece intersects with the direction of extension of the unevenness present on the contact surface of the second workpiece. (2) The processing method described in (1), A machining method further comprising an angle adjustment step, before or after the holding step, of detecting the extending direction of the irregularities of the first workpiece and the extending direction of the irregularities of the second workpiece, and adjusting the posture angle of at least one of the first workpiece and the second workpiece so that the extending direction of the irregularities of the first workpiece and the extending direction of the irregularities of the second workpiece intersect. (3) The processing method described in (2), A machining method comprising detecting the outer circumferential shapes of the first workpiece and the second workpiece in the angle adjustment step, and detecting the extending direction of the irregularities of the first workpiece and the extending direction of the irregularities of the second workpiece based on the outer circumferential shapes. (4) The processing method described in (2), A machining method comprising the angle adjustment step of irradiating the contact surface of the first workpiece and the contact surface of the second workpiece with light, detecting the reflected light reflected by the contact surface of the first workpiece and the contact surface of the second workpiece, and detecting the extending direction of the irregularities of the first workpiece and the extending direction of the irregularities of the second workpiece based on the reflected light. (5) The processing method described in (1), Before the holding step, A delamination layer formation step involves positioning the focal point of a laser beam with a wavelength that is penetrating to the ingot inside the ingot and scanning the laser beam to form a delamination layer on the ingot, A wafer production step in which the wafer is detached from the ingot starting from the aforementioned delamination layer to produce the wafer, Equipped with, The first workpiece is the ingot, and the contact surface of the first workpiece is the peeled surface from which the wafer was peeled in the wafer production step, or the first workpiece is the wafer, and the contact surface of the first workpiece is the peeled surface from which the wafer was peeled from the ingot in the wafer production step. The second workpiece is the ingot, and the contact surface of the second workpiece is the peeled surface from which the wafer was peeled in the wafer production step, or the second workpiece is the wafer, and the contact surface of the second workpiece is the peeled surface from which the wafer was peeled in the wafer production step. The direction of extension of the irregularities in the first workpiece and the direction of extension of the irregularities in the second workpiece are the scanning directions of the laser beam for the first workpiece and the second workpiece, respectively, in the peel layer formation step. A processing method in which, in the unevenness reduction step, the combination of the first workpiece and the second workpiece is one of the following combinations: ingot and ingot, wafer and wafer, and ingot and wafer, and the first workpiece and the second workpiece are brought into contact. (6) The processing method described in (1) or (2), A machining method in which, in the unevenness reduction step, the direction of extension of the unevenness of the first workpiece and the direction of extension of the unevenness of the second workpiece are fixed, and one of the first workpiece and the second workpiece is moved relative to the other in a circular manner. (7) A processing method described in (1) or (2), A machining method in which, in the unevenness reduction step, the center of the contact surface of the first workpiece is offset in the in-plane direction relative to the center of the contact surface of the second workpiece, and the first workpiece and the second workpiece are rotated in the same direction at the same speed. (8) A first holding part for holding the first workpiece, A second holding portion holds a second workpiece made of the same material as the first workpiece held in the first holding portion, facing the first workpiece held in the first holding portion, A moving mechanism for moving the first and second holding parts relative to each other in the in-plane direction of the contact surface of the first and second workpieces, while the first workpiece held by the first holding part and the second workpiece held by the second holding part are in contact with each other, Equipped with, The moving mechanism is a processing apparatus that moves the first holding part and the second holding part relative to each other so as to maintain a state in which a first direction defined within the plane of the contact surface of the first workpiece held by the first holding part and a second direction defined within the plane of the contact surface of the second workpiece held by the second holding part intersect. (9) A method for manufacturing a wafer having a thickness less than the thickness of the ingot from an ingot, A delamination layer formation step involves positioning the focal point of a laser beam having a wavelength that is transparent to the ingot inside the ingot and scanning the laser beam to form a delamination layer inside the ingot. A wafer production step in which the wafer is peeled off from the ingot starting from the peeling layer, A step to reduce the unevenness of the peeled surface of the wafer, Equipped with, The unevenness reduction step involves moving the wafer and the ingot or the other wafer relative to each other while the peeled surface of the wafer and the peeled surface of the ingot or the peeled surface of another wafer in which the unevenness reduction step has not been performed are in contact, thereby reducing the unevenness of the peeled surface of the wafer. A wafer manufacturing method comprising the above-mentioned unevenness reduction step, wherein a first direction within the peeled surface of the wafer corresponding to the scanning direction of the laser beam and a second direction within the peeled surface of the ingot corresponding to the scanning direction of the laser beam or a second direction within the peeled surface of the other wafer corresponding to the scanning direction of the laser beam are maintained to intersect, and the wafer and the ingot or the other wafer are moved relative to each other. [Explanation of symbols]

[0104] 1 ingot 5. First Orientation Flat 6. Second Orientation Flat 11 Peeling surface 20 wafers 21 Peeling surface 40 Processing equipment 41 First retaining part 50 Second retaining part 101 First workpiece 102 Contact surface 110 Second workpiece 1000 Step to form a peeling layer 1001 Wafer generation step 1002 Angle adjustment step 1003 Holding step 1004 Step to reduce unevenness 1005 Grinding Step

Claims

1. A holding step in which a first workpiece is held in a first holding part, and a second workpiece made of the same material as the first workpiece is held in a second holding part, A surface irregularity reduction step is performed in which, while the first workpiece and the second workpiece are in contact, the first workpiece and the second workpiece are moved relative to each other in the in-plane direction of the contact surface of the first workpiece and the contact surface of the second workpiece, thereby reducing the irregularities of the contact surface of the first workpiece and at least one of the contact surfaces of the second workpiece. A method for processing a workpiece, comprising: A machining method in which, in the unevenness reduction step, the first workpiece and the second workpiece are brought into contact such that the direction of extension of the unevenness present on the contact surface of the first workpiece intersects with the direction of extension of the unevenness present on the contact surface of the second workpiece.

2. The processing method according to claim 1, A machining method further comprising an angle adjustment step, before or after the holding step, of detecting the extending direction of the irregularities of the first workpiece and the extending direction of the irregularities of the second workpiece, and adjusting the posture angle of at least one of the first workpiece and the second workpiece so that the extending direction of the irregularities of the first workpiece and the extending direction of the irregularities of the second workpiece intersect.

3. The processing method according to claim 2, A machining method comprising detecting the outer circumferential shapes of the first workpiece and the second workpiece in the angle adjustment step, and detecting the extending direction of the irregularities of the first workpiece and the extending direction of the irregularities of the second workpiece based on the outer circumferential shapes.

4. The processing method according to claim 2, A machining method comprising the angle adjustment step of irradiating the contact surface of the first workpiece and the contact surface of the second workpiece with light, detecting the reflected light reflected by the contact surface of the first workpiece and the contact surface of the second workpiece, and detecting the extending direction of the irregularities of the first workpiece and the extending direction of the irregularities of the second workpiece based on the reflected light.

5. The processing method according to claim 1, Before the holding step, A delamination layer formation step involves positioning the focal point of a laser beam with a wavelength that is penetrating to the ingot inside the ingot and scanning the laser beam to form a delamination layer on the ingot, A wafer production step in which the wafer is detached from the ingot starting from the aforementioned delamination layer to produce the wafer, Equipped with, The first workpiece is the ingot, and the contact surface of the first workpiece is the peeled surface from which the wafer was peeled in the wafer production step, or the first workpiece is the wafer, and the contact surface of the first workpiece is the peeled surface from which the ingot was peeled in the wafer production step. The second workpiece is the ingot, and the contact surface of the second workpiece is the peeled surface from which the wafer was peeled in the wafer production step, or the second workpiece is the wafer, and the contact surface of the second workpiece is the peeled surface from which the wafer was peeled in the wafer production step. The direction of extension of the irregularities in the first workpiece and the direction of extension of the irregularities in the second workpiece are the scanning directions of the laser beam for the first workpiece and the second workpiece, respectively, in the peel layer formation step. A processing method in which, in the unevenness reduction step, the combination of the first workpiece and the second workpiece is one of the following combinations: ingot and ingot, wafer and wafer, and ingot and wafer, and the first workpiece and the second workpiece are brought into contact.

6. A processing method according to claim 1 or 2, A machining method in which, in the unevenness reduction step, the direction of extension of the unevenness of the first workpiece and the direction of extension of the unevenness of the second workpiece are fixed, and one of the first workpiece and the second workpiece is moved relative to the other in a circular manner.

7. A processing method according to claim 1 or 2, A machining method in which, in the unevenness reduction step, the center of the contact surface of the first workpiece is offset in the in-plane direction relative to the center of the contact surface of the second workpiece, and the first workpiece and the second workpiece are rotated in the same direction at the same speed.

8. A first holding part for holding the first workpiece, A second holding portion holds a second workpiece made of the same material as the first workpiece held in the first holding portion, facing the first workpiece held in the first holding portion, A moving mechanism for moving the first and second holding parts relative to each other in the in-plane direction of the contact surface of the first and second workpieces, while the first workpiece held by the first holding part and the second workpiece held by the second holding part are in contact with each other, Equipped with, The moving mechanism is a processing apparatus that moves the first holding part and the second holding part relative to each other so as to maintain a state in which a first direction defined within the plane of the contact surface of the first workpiece held by the first holding part and a second direction defined within the plane of the contact surface of the second workpiece held by the second holding part intersect.

9. A wafer manufacturing method for producing a wafer having a thickness less than the thickness of the ingot from an ingot, A delamination layer formation step involves positioning the focal point of a laser beam having a wavelength that is transparent to the ingot inside the ingot and scanning the laser beam to form a delamination layer inside the ingot. A wafer production step in which the wafer is peeled off from the ingot starting from the peeling layer, A step to reduce the unevenness of the peeled surface of the wafer, Equipped with, The unevenness reduction step involves moving the wafer and the ingot or the other wafer relative to each other while the peeled surface of the wafer and the peeled surface of the ingot or the peeled surface of another wafer in which the unevenness reduction step has not been performed are in contact, thereby reducing the unevenness of the peeled surface of the wafer. A wafer manufacturing method comprising the above-mentioned unevenness reduction step, wherein a first direction within the peeled surface of the wafer corresponding to the scanning direction of the laser beam and a second direction within the peeled surface of the ingot corresponding to the scanning direction of the laser beam or a second direction within the peeled surface of the other wafer corresponding to the scanning direction of the laser beam are maintained to intersect, and the wafer and the ingot or the other wafer are moved relative to each other.

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