Grinding device

Abstract

To improve form accuracy of a wafer formed by grinding work performed after preprocessing and improve efficiency of grinding work of the wafer.SOLUTION: A grinding device includes at least one plasma generator 10a that applies plasma to at least a part of an outer peripheral edge of a wafer before grinding the outer peripheral edge.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a grinding device. [Background technology]

[0002] Wafers made from single-crystal materials are used in the manufacture of semiconductors. In particular, SiC (silicon carbide) semiconductors are manufactured using SiC wafers made from single-crystal SiC. The manufacturing process for such SiC semiconductors involves a step of growing an epitaxial thin film on the SiC wafer (epicapital growth step), resulting in the production of SiC epitaxial wafers.

[0003] However, because defects are likely to occur in the outer periphery of a SiC epitaxial wafer, a grinding technique is used to grind the outer periphery of the SiC wafer prior to the epitaxial growth process. One example of such a grinding technique is disclosed in Patent Document 1, in which the outer peripheral edge of the SiC wafer is roughly ground with a grinding wheel such as a metal-bonded grinding wheel, and then this outer peripheral edge is finish-ground with a grinding wheel such as a resin-bonded grinding wheel. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2016-032002 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the above-mentioned grinding technique, the SiC wafer to be roughly polished is a difficult-to-cut material with sharp edges, and the grindstone used for rough polishing of such SiC wafers is easily worn, and further repeated rough polishing may cause the shape of the grindstone to change.

[0006] If the shape of the grinding wheel for rough polishing changes in this way, the shape accuracy of the SiC wafer formed by the grinding wheel after rough polishing may decrease, and further, the shape accuracy of the SiC wafer after finish polishing may decrease. Furthermore, if the shape of the grinding wheel for rough polishing changes, maintenance work such as replacing the grinding wheel must be performed more frequently. This causes a decrease in the efficiency of the grinding work for SiC wafers.

[0007] In view of the above circumstances, an object of the present invention is to provide a grinding apparatus that can improve the accuracy of the shape of a wafer formed by a grinding operation and can improve the efficiency of the wafer grinding operation. [Means for solving the problem]

[0008] The present invention has the following configurations for solving the above problems. [1] A grinding apparatus comprising at least one plasma generator for applying plasma to at least a portion of the outer peripheral edge of a wafer before grinding the outer peripheral edge. [2] The grinding apparatus according to [1], wherein the plasma generator has a plurality of plasma generators, each of which has a nozzle for emitting plasma, and the nozzles of the plurality of plasma generators each face two corners of the outer circumferential edge of the wafer in the thickness direction. [3] The grinding apparatus according to [2], wherein the nozzles of the plurality of plasma generators are each tiltable. [4] A grinding apparatus as described in [1], which has a rotating device used to rotate the wafer around its central axis, a grinding unit equipped with a grinding stone unit that grinds the outer peripheral portion of the wafer and a drive unit that rotates the grinding stone unit, and the plasma generator is capable of irradiating plasma to a pre-processing target portion that moves circumferentially on the wafer as the wafer rotates around its central axis. [5] A grinding apparatus as described in [4], comprising a control device and an arithmetic device capable of calculating at least one of the optimal conditions for plasma irradiation by the plasma generator and the optimal conditions for grinding by the grinding unit, wherein the control device is capable of controlling at least one of the plasma generator and the grinding unit so as to conform to at least one of the optimal conditions for plasma irradiation and the optimal conditions for grinding calculated by the arithmetic device. [6] A grinding apparatus as described in [5], which is provided with a surface inspection device capable of inspecting the surface condition of the wafer, wherein the arithmetic device is capable of calculating an optimal value for at least one of the power and diameter of the plasma and the rotation speed of the wafer based on data on the surface condition as the optimal condition for irradiating the plasma, and the control device is capable of controlling the plasma generator and the rotation device to conform to the optimal value. [7] A grinding apparatus as described in [5], comprising at least one of a shape inspection device capable of inspecting the shape of the wafer and a crystal inspection device capable of inspecting the crystalline state of the wafer, wherein the arithmetic device is capable of calculating an optimal value for at least one of the cutting depth and rotation speed of the grinding stone section and the rotation speed of the wafer based on at least one of the shape and the crystalline state as the optimal condition for the grinding, and the control device is capable of controlling the grinding section and the rotation device to conform to the optimal value. [8] The grinding apparatus according to [4], comprising a plurality of the plasma generators arranged at intervals in the circumferential direction of the wafer. [Effects of the Invention]

[0009] According to the grinding device of the present invention, it is possible to improve the accuracy of the shape of the wafer formed by the grinding operation, and also to improve the efficiency of the wafer grinding operation. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram of a grinding device according to a first embodiment. [Figure 2] FIG. 2 is a schematic plan view of the main part of the grinding device according to the first embodiment. [Figure 3] FIG. 3 is a view seen from the arrow V in FIG. [Figure 4] FIG. 4 is a view seen from the arrow W in FIG. [Figure 5] FIG. 5 is a cross-sectional view taken along line XX in FIG. [Figure 6] FIG. 6 is a cross-sectional view taken along line YY in FIG. [Figure 7] FIG. 7 is a cross-sectional view taken along line ZZ in FIG. [Figure 8] FIG. 8 is a flowchart for explaining the grinding method using the grinding device according to the first embodiment. [Figure 9] FIG. 9 is a flowchart for explaining a method for optimizing the conditions for plasma irradiation by the pretreatment device in the grinding device according to the first embodiment. [Figure 10] FIG. 10 is a flowchart for explaining a method for optimizing grinding conditions in the grinding device according to the first embodiment. [Figure 11] FIG. 11 is a schematic plan view of the main part of the grinding device according to the second embodiment. [Figure 12] FIG. 12 is a block diagram of a grinding device according to the third embodiment. [Figure 13] FIG. 13 is a schematic plan view of the main part of the grinding device according to the third embodiment. [Figure 14] FIG. 14 is a cross-sectional view that schematically illustrates a state in which two corners in the outer periphery of a wafer are irradiated with plasma in the third embodiment. [Figure 15] FIG. 15 is a schematic plan view of the grinding device according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] The grinding devices according to the first to fourth embodiments will be described below.

[0012] A grinding device according to a first embodiment will be described below with reference to Figures 1 to 9. With reference to Figures 1 to 7, the grinding device according to this embodiment is generally configured as follows.

[0013] 1 to 5, a grinding apparatus 100 according to this embodiment can irradiate plasma to a processing target area G (indicated by a grid-like hatched line in FIG. 5), which is at least a part of the outer peripheral portion 2 of a disk-shaped wafer 1, as a pretreatment before grinding with a grindstone in order to grind the outer peripheral portion 2 of the wafer 1. In other words, plasma-assisted grinding is possible. The grinding apparatus 100 has a pretreatment apparatus 10 including a plasma generator 10a that can irradiate the processing target area G with plasma J to modify the processing target area G.

[0014] 2 to 5, the grinding apparatus 100 has two plasma generators 10a. Each plasma generator 10a has a nozzle 10c that can emit the plasma J toward the outside along an irradiation axis 10b. However, the grinding apparatus 100 may have one or three or more plasma generators.

[0015] The wafer 1 is a SiC (silicon carbide) wafer 1. As shown in Fig. 5, an outer peripheral portion 2 of the wafer 1 has, as a processing target portion G, two corners 3 located at both ends of the central axis direction (indicated by double-sided arrow A) of the wafer 1. The two plasma generators 10a are arranged so that the nozzles 10c of the two plasma generators 10a face the two corners 3, respectively, so that the plasma J can be directed toward the two corners 3, respectively.

[0016] In the wafer 1, each corner 3 has a shape that is removed for chamfering. The two plasma generators 10a are arranged at a distance from each other in the direction of the central axis of the wafer 1. The nozzle 10c of each plasma generator 10a is arranged so that its irradiation axis 10b is inclined so that the nozzle 10c can irradiate the opposite corner 3 with plasma J in accordance with the shape of the corner 3.

[0017] 1 to 7, the grinding apparatus 100 according to this embodiment is generally configured as follows. As shown in FIGS. 1 to 5, the grinding apparatus 100 includes the above-described pretreatment apparatus 10. The plasma generator 10a of the pretreatment apparatus 10 is capable of irradiating plasma J to a processing target G that moves in the circumferential direction of the wafer 1 (indicated by two one-sided arrows U and D) as the wafer 1 rotates about the central axis 1a of the wafer 1.

[0018] 1 to 4, 6, and 7, the grinding apparatus 100 has two grinding units (rough grinding unit 20 and finish grinding unit 30) capable of grinding the outer peripheral portion 2 of the wafer 1. The two grinding units have grinding stone units 21 and 31 capable of grinding the outer peripheral portion 2 of the wafer 1, which moves from one side of the circumference of the wafer 1 (indicated by the one-sided arrow U in FIG. 2) to the other side (indicated by the one-sided arrow D in FIG. 2) as the wafer 1 turns. The two grinding units have driving units 22 and 32, respectively, which enable the grinding stone units 21 and 31 to turn in the opposite direction to the wafer 1.

[0019] 1 and 4, the grinding apparatus 100 has a turning device 40 that is used to turn the wafer 1 about its central axis 1a when the wafer 1 is pre-processed by the pre-processing device 10 and when the wafer 1 is ground by the grinding unit. As shown in FIG. 1, the grinding apparatus 100 has a control device 50 that can control the pre-processing device 10, the grinding unit, and the turning device 40.

[0020] The grinding apparatus 100 has a calculation device 51 that can calculate at least one of the optimum conditions for irradiation of plasma J by the pretreatment device 10 and the optimum conditions for grinding by the grinding unit. The control device 50 can control at least one of the pretreatment device 10 (plasma generator), the grinding unit, and the turning device 40 so as to conform to at least one of the optimum conditions for irradiation of plasma J and the optimum conditions for grinding calculated by the calculation device 51.

[0021] The grinding apparatus 100 has a surface inspection device 52 that can inspect the surface condition of the processing target portion G modified by the pretreatment device 10. The calculation device 51 can calculate an optimal value for at least one of the power and diameter of the plasma J and the rotation speed of the wafer 1 based on data on the surface condition of the processing target portion G obtained by the surface inspection device 52 as the optimal conditions for irradiating the plasma J. The control device 50 can control the pretreatment device 10 (plasma generator) and the rotation device 40 so as to conform to at least one of the optimal values ​​calculated by the calculation device 51 among the power and diameter of the plasma J and the rotation speed of the wafer 1.

[0022] The grinding device 100 has at least one of a shape inspection device 53 that can inspect the shape of the wafer 1 ground by the grinding unit and a crystal inspection device 54 that can inspect the crystalline state of the wafer 1 ground by the grinding unit.

[0023] The arithmetic device 51 is capable of calculating, as the optimum grinding conditions, at least one optimum value of the cutting depth and rotation speed of the grinding stone units 21 and 31 and the rotation speed of the wafer 1, based on at least one of data on the shape of the wafer 1 obtained by the shape inspection device 53 and data on the crystalline state of the wafer 1 obtained by the crystal inspection device 54. The control device 50 is capable of controlling the grinding unit and the rotation device 40 so as to conform to at least one optimum value of the cutting depth and rotation speed of the grinding stone units 21 and 31 and the rotation speed of the wafer 1 calculated by the arithmetic device 51.

[0024] 4, the turning device 40 has a turning mechanism 41 that turns the wafer 1 about its central axis 1a at a fixed position when the wafer 1 is pre-processed by the pre-processing device 10 and when the wafer 1 is ground by the grinding unit. The pre-processing device 10 is disposed on one side of the wafer 1 in the circumferential direction relative to the grinding unit.

[0025] However, the turning device is not limited to this. For example, the turning device may have a pre-processing turning mechanism that turns the wafer about its central axis when the pre-processing device is pre-processing the wafer, and a grinding turning mechanism that turns the wafer about its central axis when the grinding device is grinding the wafer. In this case, the pre-processing turning mechanism and the grinding turning mechanism are located apart from each other. In addition, a transport device, which will be described later, can transport wafers between the pre-processing turning mechanism and the grinding turning mechanism.

[0026] The wafer 1 to be processed can be as follows in detail. The types of wafer 1 will be explained. First, the wafer 1 can be a SiC wafer 1 as described above. That is, the material of the wafer 1 can be SiC. In particular, the material of the SiC wafer can be 4H-SiC, 6H-SiC, 3C-SiC, etc. However, the material of the wafer can also be Si (silicon), GaAs (gallium arsenide), etc.

[0027] As shown in Figure 5, the processing target area G of the wafer 1 is two corners 3 on the outer peripheral portion 2 of the wafer 1. When the outer peripheral portion 2 of the wafer 1 is viewed in cross section along the central axis 1a of the wafer 1, the range of each corner 3 can be a substantially triangular range. The range of each corner 3 can be defined as being surrounded by a first side along one side of the wafer 1 in the central axis direction, a second side along the outer peripheral surface of the wafer 1, and a third side extending inside the wafer 1 to connect the first side and the outer peripheral surface.

[0028] 1 to 5, the grinding apparatus 100 according to this embodiment can be specifically configured as follows. In the grinding apparatus 100, the plasma generator 10a is a plasma jet generator. Such a plasma generator 10a is capable of irradiating a water vapor plasma jet under atmospheric pressure. However, the plasma generator is not limited to a plasma jet generator. For example, the plasma generator can also be a plasma torch.

[0029] The processing target G irradiated with plasma J by the plasma generator 10a is modified as follows. When the material of the wafer 1 is SiO, particularly 4H-SiO, and the processing target G of the wafer 1 is irradiated with plasma by the plasma generator 10a, OH radicals are generated as reactive species. These OH (hydroxyl) radicals modify the processing target G to SiO2. In this case, the processing target G is softened.

[0030] The plasma generator 10a can be configured to raster scan the plasma J over the entire corner 3 facing the nozzle 10c in the radial direction of the wafer 1. In this case, the position of the nozzle 10c, the power and diameter of the plasma J from the nozzle 10c, and the rotation speed of the wafer 1 can be adjusted appropriately to accurately modify the entire corner 3 facing the nozzle 10c.

[0031] The plasma J emitted from the nozzle 10c of the plasma generator 10a is emitted along an emission axis 10b. The emission axis 10b substantially coincides with the central axis of the plasma J. Furthermore, the pretreatment device 10 is configured to enable the plasma J to be emitted simultaneously from the two plasma generators 10a. The two plasma generators 10a can simultaneously emit their plasma J to the two corners 3, respectively. As an example, the maximum output of the plasma generator 10a can be approximately 1.5 kW.

[0032] 1 to 7, the grinding device 100 according to this embodiment can be configured in detail as follows: The grinding device 100 has two grinding units.

[0033] As shown in Figures 1 to 4 and 6, one of the two grinding devices 100 is a rough grinding unit 20 that can roughly grind the outer peripheral portion 2 of the wafer 1 that has been preprocessed by the preprocessing device 10. As shown in Figures 1 to 4 and 7, the other of the two grinding units is a finish grinding unit 30 (precision grinding unit) that can finish grind the outer peripheral portion 2 of the wafer 1 that has been rough ground by the rough grinding unit 20. As shown in Figure 2, the rough grinding unit 20 is located on one side of the finish grinding unit 30 in the rotation direction of the wafer 1 (indicated by a one-sided arrow U).

[0034] 2 to 4 and 6, the rough grinding unit 20 has a grindstone unit 21 that can roughly grind the outer periphery 2 of the wafer 1 after preprocessing by the preprocessing device 10. The grindstone unit 21 is formed so as to be able to grind at least two corners 3 on the outer periphery 2 of the wafer 1. During rough grinding by the rough grinding unit 20, the outer periphery 2 of the wafer 1 moves from one side to the other in the circumferential direction of the wafer 1 as the wafer 1 turns.

[0035] 1 to 4 and 6, the rough grinding unit 20 has a drive unit 22 that can rotate the grinding stone unit 21 in the direction opposite to the wafer 1. The rough grinding unit 20 can have a cutting-in amount adjustment unit 23 that can adjust the cutting-in amount of the grinding stone unit 21 into the outer peripheral portion 2 of the wafer 1. The cutting-in amount adjustment unit 23 is configured to be able to move the grinding stone unit 21 in a direction approaching the wafer 1 and a direction away from the wafer 1.

[0036] For example, such a cutting depth adjustment unit 23 can operate the grinding stone unit 21 to move it away from the outer peripheral portion 2 of the wafer 1 before the pre-treatment device 10 irradiates the processing target portion G of the outer peripheral portion 2 of the wafer 1 with plasma J, and can operate the grinding stone unit 21 to roughly grind the outer peripheral portion 2 of the wafer 1 after the pre-treatment device 10 irradiates the processing target portion G of the outer peripheral portion 2 of the wafer 1 with plasma J.

[0037] 2 to 4 and 7, the finish grinding unit 30 has a grindstone unit 31 that can perform finish grinding on the outer peripheral portion 2 of the wafer 1 after rough grinding by the rough grinding unit 20. The grindstone unit 31 is formed to correspond to the finished shape of the outer peripheral portion 2 of the wafer 1. During finish grinding by the finish grinding unit 30, the outer peripheral portion 2 of the wafer 1 moves from one side to the other in the circumferential direction of the wafer 1 as the wafer 1 rotates. Note that the finish grinding unit 30 may be a helical grinding device that performs grinding by tilting the rotation axis of the grindstone unit 31 with respect to the rotation axis of the wafer 1.

[0038] 1 to 4 and 7, the finish grinding unit 30 has a drive unit 32 that can rotate the grinding stone unit 31 in the direction opposite to the wafer 1. The finish grinding unit 30 can have a cutting-in amount adjustment unit 33 that can adjust the cutting-in amount of the grinding stone unit 31 into the outer peripheral portion 2 of the wafer 1. The cutting-in amount adjustment unit 33 is configured to be able to move the grinding stone unit 31 in a direction toward the wafer 1 and a direction away from the wafer 1.

[0039] For example, such a cutting depth adjustment unit 33 can operate the grinding stone unit 31 to move away from the outer peripheral portion 2 of the wafer 1 before the rough grinding unit 20 roughly grinds the outer peripheral portion 2 of the wafer 1, and can operate the grinding stone unit 31 to finish grind the outer peripheral portion 2 of the wafer 1 after the rough grinding unit 20 rough grinds the outer peripheral portion 2 of the wafer 1.

[0040] 1 and 4, in the grinding apparatus, a turning mechanism 41 of a turning device 40 has a fixing part 42 that can fix a wafer 1. The fixing part 42 is configured to be switchable between a state in which the wafer 1 is fixed and a state in which the fixation of the wafer 1 is released. The turning mechanism 41 has a driving part 43 that can turn the fixing part 42 together with the wafer 1 around the central axis 1a of the wafer 1.

[0041] As shown in Fig. 5, plasma J from the pretreatment device 10 is irradiated onto the processing target G of the outer peripheral portion 2 of the wafer 1 being rotated by the rotation mechanism 41. This irradiation modifies the processing target G, which extends along the entire circumference of the outer peripheral portion 2 of the wafer 1. Furthermore, as shown in Figs. 6 and 7, the entire outer peripheral portion 2 of the wafer 1 being rotated by the rotation mechanism 41 is ground by two grinding devices.

[0042] 1, the control device 50 has a processor 50a, a memory 50b, and an input / output unit 50c. The processor 50a is an integrated circuit for control. For example, the processor 50a may be a CPU (Central Processing Unit), a microcontroller, or the like. The processor 50a may also be configured to have a working RAM (Random Access Memory), not shown.

[0043] The memory 50b is a general information storage medium. The memory 50b may be a non-volatile memory. For example, the memory 50b may be a ROM (Read Only Memory), an EEPROM (Electrically Erasable Programmable Read Only Memory), a flash memory, a hard disk, or the like. The memory 50b may store programs, various data, and the like.

[0044] The input / output unit 50c serves as an interface for electrically connecting the control device 50 to the pre-processing device 10, the grinding device, the turning device 40, and the arithmetic device 51. The input / output unit 50c also serves as an interface for electrically connecting the control device 50 to the surface inspection device 52. Furthermore, the input / output unit 50c serves as an interface for electrically connecting the control device 50 to at least one of the shape inspection device 53 and the crystal inspection device 54.

[0045] The arithmetic device 51 can be configured to have a processor 51a, a memory 51b, and an input / output unit 51c, similar to the control device 50. The arithmetic device 51 can have a machine learning model for pre-processing inspection that can calculate an optimal value for at least one of the power and diameter of the plasma J and the rotation speed of the wafer 1, based on data on the surface condition of the processing target portion G obtained by the surface inspection device 52. The above machine learning model can be generated based on a dataset (training dataset) having multiple entries that correlate wafer pre-processing conditions (power and diameter of plasma J, and rotation speed of wafer 1) with the resulting surface state.

[0046] However, the computing device is not limited to a configuration having a machine learning model for pre-processing inspection. For example, the computing device may perform statistical analysis for pre-processing inspection to calculate an optimal value for at least one of the power and diameter of the plasma and the rotation speed of the wafer 1 based on data on the surface condition of the pre-processing target portion obtained by the surface inspection device.

[0047] The calculation device 51 has a machine learning model for grinding evaluation that can calculate the optimal value of at least one of the cutting depth and rotation speed of the grinding wheel parts 21, 31, and the rotation speed of the wafer 1 based on at least one of the data on the shape of the wafer 1 (shape dimensions, surface roughness, etc.) obtained by the shape inspection device 53 and the data on the crystal state of the wafer 1 obtained by the crystal inspection device 54.

[0048] However, the computing device 51 is not limited to a configuration having a machine learning model for evaluating pre-processing. For example, the computing device 51 can also perform statistical analysis for evaluating pre-processing to calculate an optimal value for at least one of the power and diameter of the plasma and the rotation speed of the wafer 1, based on data on the surface condition of the pre-processing target portion obtained by the surface inspection device.

[0049] The surface inspection device 52 can be configured to perform XPS (X-ray photoelectron spectroscopy) analysis, TEMS (Transmission Electron Microscope) / STEM (Scanning Transmission Electron Microscope) analysis, etc. on the processing target portion G after irradiation with the plasma J. Such a surface inspection device 52 can measure the elemental composition and chemical bonding state of the processing target portion G after irradiation with the plasma J. In other words, the surface state obtained by the surface inspection device 52 can be the elemental composition and chemical bonding state.

[0050] The shape inspection device 53 can be configured to measure the shape dimensions, surface roughness, etc. of the wafer 1, particularly the outer peripheral portion 2 of the wafer 1. The shape inspection device 53 is preferably a non-contact type. For example, the shape inspection device 53 can be the LEP series manufactured by Kobelco (registered trademark), the LJ-X series manufactured by Keyence (registered trademark), an optoscope manufactured by Tokyo Seimitsu (registered trademark), or the like.

[0051] The crystal inspection device 54 can be configured to inspect the crystal structure of the wafer 1, particularly the outer peripheral portion 2 of the wafer 1, by Raman spectroscopy, X-ray 3D topography, XRD (X-ray diffraction), or the like.

[0052] Furthermore, the grinding apparatus 100 may have a transport device 55 capable of transporting the wafer 1. The transport device 55 may transport the wafer 1 between the turning device 40, the surface inspection device 52, and the shape and / or crystal inspection devices 53 and 54. For example, such a transport device 55 may be configured to transport the wafer 1 using an arm (not shown) capable of gripping the wafer 1.

[0053] A grinding method using the grinding apparatus 100 according to this embodiment will be described with reference to Fig. 8. First, the wafer 1 is fixed to the fixing portion 42 of the turning mechanism 41 of the turning device 40 (step S1). At this time, the control device 50 can control the fixing portion 42 so that the wafer 1 is in a fixed state. The wafer 1 is turned by the driving portion 43 of the turning mechanism 41, and this turned state is maintained (step S2).

[0054] The processing target G of the outer peripheral portion 2 of the wafer 1 in the rotated state is irradiated with plasma J from the plasma generator 10a of the pre-processing device 10 (step S3). The outer peripheral portion 2 of the wafer 1 in the rotated state after being irradiated with plasma J is roughly ground by the grinding wheel unit 21 of the rough grinding unit 20 which rotates in the opposite direction to the wafer 1 (step S4).

[0055] The outer peripheral portion 2 of the wafer 1 after rough grinding, which is in a rotated state, is finish-ground by the grindstone unit 31 of the finish grinding unit 30, which rotates in the opposite direction to the wafer 1 (step S5). The rotation of the wafer 1 by the driving unit 43 is stopped (step S6). The fixing unit 42 releases the fixation of the wafer 1 after finish grinding (step S7). At this time, the control device 50 can control the fixing unit 42 to release the fixation of the wafer 1.

[0056] 9, a method for optimizing the conditions for irradiating the plasma J by the pretreatment device 10 in the grinding device 100 according to this embodiment will be described. The surface inspection device 52 inspects the surface state of the processing target portion G on the wafer 1 after irradiation with a plurality of plasmas J (step S11). A plurality of pieces of surface state data obtained by this inspection are input to the calculation device 51 (step S12).

[0057] The arithmetic device 51 calculates and outputs an optimum value for at least one of the power and diameter of the plasma J and the rotation speed of the wafer 1 based on the input data on the surface state (step S13). The control device 50 controls the pre-treatment device 10 and the rotation device 40 so as to match the optimum value for at least one of the power and diameter of the output plasma J and the rotation speed of the wafer 1 (step S14).

[0058] A method for optimizing the grinding conditions by the grinding unit in the grinding apparatus 100 according to this embodiment will be described with reference to Fig. 10. The shape inspection device 53 inspects the shape of the wafer 1 after multiple finish grindings (step S21). The crystal inspection device 54 inspects the crystalline state of the wafer 1 after multiple finish grindings (step S22). Data on the shapes and crystalline states obtained by these inspections are input to the calculation device 51 (step S23).

[0059] The arithmetic device 51 calculates and outputs an optimum value for at least one of the cutting depth and rotation speed of the grinding stone units 21, 31 in the rough grinding unit 20 and the finish grinding unit 30, and the rotation speed of the wafer 1, based on the input data on the plurality of shapes and the plurality of data on the crystal state (step S24). The control device 50 controls the rough grinding unit 20, the finish grinding unit 30, and the rotation device 40 so as to conform to the output optimum value for at least one of the cutting depth and rotation speed of the grinding stone units 21, 31 in the rough grinding unit 20 and the finish grinding unit 30, and the rotation speed of the wafer 1 (step S25).

[0060] As described above, the pre-treatment device 10 according to this embodiment has a plasma generator 10a that can irradiate plasma J onto the treatment target G, which is at least a part of the outer peripheral portion 2 of the wafer 1, in order to modify the treatment target G before grinding the outer peripheral portion 2 of the disk-shaped wafer 1.

[0061] According to such a pretreatment device 10, the processing target portion G can be softened by irradiating it with plasma J. Therefore, in the grinding operation performed after irradiating it with plasma J, the softened outer peripheral portion 2 of the wafer 1 can be efficiently ground.

[0062] Furthermore, wear of the grindstone portions 21, 31 can be suppressed when grinding the outer peripheral portion 2 of the wafer 1 including the softened processing target portion G. As a result, the accuracy of the shape of the wafer 1 shaped by such grindstone portions 21, 31 can be improved. Therefore, the accuracy of the shape of the wafer 1 shaped by grinding performed after pre-processing can be improved, and the efficiency of the grinding operation of the wafer 1 can be improved.

[0063] The pretreatment device 10 according to this embodiment includes two plasma generators 10a, each having a nozzle 10c that enables the plasma J to be emitted outward along an irradiation axis 10b, the wafer 1 being a SiC wafer 1, the peripheral portion 2 of the wafer 1 having, as the processing target portion G, two corners 3 located at both ends of the central axis of the wafer 1, and the two plasma generators 10a are arranged so that the nozzles 10c of the two plasma generators 10a face the two corners 3, respectively, so that the plasma J can be irradiated toward the two corners 3, respectively.

[0064] With this pretreatment device 10 (plasma generator), the sharp corners 3 of the outer periphery 2 of the wafer 1 can be softened by irradiating the wafer with plasma J. Therefore, in the grinding operation performed after irradiating the wafer with plasma J, the softened corners 3 of the outer periphery 2 of the wafer 1 can be efficiently ground. Furthermore, wear of the grindstones 21, 31 can be suppressed when grinding the outer periphery 2 of the wafer 1, including the softened corners 3. As a result, the shape precision of the wafer 1 shaped by the grindstones 21, 31 can be improved.

[0065] In the pretreatment device 10 according to this embodiment, the shape of each corner 3 is removed for chamfering, and two plasma generators 10a are arranged spaced apart from each other in the direction of the central axis of the wafer 1, and the nozzle 10c of each plasma generator 10a is arranged so that its irradiation axis 10b is inclined so that the plasma J can be irradiated to the entire corner 3 opposite it.

[0066] According to such a pretreatment device 10, the entire corners 3 of the outer periphery 2 of the wafer 1 can be accurately softened by irradiating the wafer with plasma J. Therefore, in the grinding operation of the wafer 1 performed after the irradiation with plasma J, the outer periphery 2 of the wafer 1, including the softened corners 3, can be efficiently ground.

[0067] The grinding apparatus 100 according to this embodiment includes the pretreatment apparatus 10 according to this embodiment, two grinding units capable of grinding the outer peripheral portion 2 of the wafer 1, and a turning device 40 used to turn the wafer 1 about its central axis 1a when the pretreatment apparatus 10 pretreatments the wafer 1 and when the grinding units grind the wafer 1. The plasma generator 10a of the pretreatment apparatus 10 is capable of irradiating plasma J to the processing target portion G that moves in the circumferential direction of the wafer 1 as the wafer 1 turns about the central axis 1a, and the grinding unit has grinding stone units 21 and 31 that can grind the outer peripheral portion 2 of the wafer 1 that moves from one side to the other in the circumferential direction of the wafer 1 as the wafer 1 turns, and driving units 22 and 32 that can turn the grinding stone units 21 and 31 in the direction opposite to the wafer 1.

[0068] Such a grinding device can improve the shape accuracy of the wafer 1 formed by grinding at the two grinding sections after pre-processing by the pre-processing device 10, and can also improve the efficiency of the grinding work for the wafer 1.

[0069] The grinding apparatus 100 according to this embodiment has a control device 50 capable of controlling the pre-processing device 10, the grinding unit, and the rotating device 40, and an arithmetic unit 51 capable of calculating at least one of the optimal conditions for the irradiation of plasma J by the pre-processing device 10 and the optimal conditions for grinding by the grinding unit, and the control device 50 is capable of controlling at least one of the pre-processing device 10, the grinding unit, and the rotating device 40 so as to conform to at least one of the optimal conditions for the irradiation of plasma J and the optimal conditions for grinding calculated by the arithmetic unit 51.

[0070] According to such a grinding apparatus 100, the conditions for irradiating the processing target portion G with plasma J from the pretreatment device 10 can be optimized so as to accurately soften the entire processing target portion G, and the conditions for grinding the wafer 1 by the grinding unit can be optimized so as to increase the shape accuracy of the wafer 1 formed by this grinding.

[0071] The grinding apparatus 100 of this embodiment has a surface inspection device 52 that can inspect the surface condition of the processing target portion G modified by the pre-processing device 10, and the calculation device 51 can calculate at least one optimal value of the power and diameter of the plasma J and the rotation speed of the wafer 1 based on the data on the surface condition of the processing target portion G obtained by the surface inspection device 52 as the optimal condition for irradiating the plasma J, and the control device 50 can control the pre-processing device 10 and the rotation device 40 to conform to at least one optimal value of the power and diameter of the plasma J and the rotation speed of the wafer 1 calculated by the calculation device 51.

[0072] According to such a grinding apparatus 100, at least one of the power and diameter of the plasma J irradiated from the pretreatment apparatus 10 to the processing target portion G and the rotation speed of the wafer 1 can be optimized so as to accurately soften the entire processing target portion G.

[0073] The grinding apparatus 100 of this embodiment has at least one of a shape inspection device 53 that can inspect the shape of the wafer 1 ground by the grinding apparatus 100 and a crystal inspection device 54 that can inspect the crystalline state of the wafer 1 ground by the grinding apparatus 100, and the calculation device 51 is capable of calculating, as the optimal grinding conditions, at least one of the cutting depth and rotation speed of the grinding stone unit 21, 31 and the rotation speed of the wafer 1 based on at least one of the data on the shape of the wafer 1 obtained by the shape inspection device 53 and the data on the crystalline state of the wafer 1 obtained by the crystal inspection device 54, and the control device 50 is capable of controlling the grinding unit and the rotation device 40 to conform to at least one of the optimal values ​​of the cutting depth and rotation speed of the grinding stone unit 21, 31 and the rotation speed of the wafer 1 calculated by the calculation device 51.

[0074] According to such a grinding apparatus 100, at least one of the cutting depth and rotation speed of the grinding stone sections 21, 31 in the grinding apparatus 100 and the rotation speed of the wafer 1 can be optimized to improve the shape accuracy of the wafer 1 formed by grinding with the grinding section.

[0075] In the grinding apparatus 100 of this embodiment, the turning device 40 has a turning mechanism 41 that turns the wafer 1 around its central axis 1a at a fixed position when the wafer 1 is pre-processed by the pre-processing device 10 and when the wafer 1 is ground by the grinding section, and the pre-processing device 10 is arranged on one side of the wafer 1 in the circumferential direction relative to the grinding section.

[0076] With such a grinding apparatus 100, the processing target portion G of the outer peripheral portion 2 of the wafer 1 is softened by the plasma J of the pretreatment device 10, and then the outer peripheral portion 2 of the wafer 1 including the softened processing target portion G is ground by the grinding apparatus, which is a series of steps that can be carried out smoothly and efficiently.

[0077] A grinding apparatus 200 according to the second embodiment will be described below with reference to Fig. 11. The pre-processing device 10 included in the grinding apparatus 200 is similar to the pre-processing device 10 included in the grinding apparatus 100 according to the first embodiment. The grinding apparatus 100 according to this embodiment is similar to the grinding apparatus 100 according to the first embodiment, except that it does not have a rough grinding unit 20.

[0078] The grinding method using the grinding apparatus 200 according to this embodiment differs from the grinding method using the grinding apparatus 100 according to the first embodiment in that it does not include step S4 related to rough grinding and does not use the rough grinding unit 20. In this grinding method, plasma J from the plasma generator 10a of the pretreatment device 10 is irradiated onto the processing target G of the outer peripheral portion 2 of the wafer 1 in a rotated state, and then the outer peripheral portion 2 of the wafer 1 after irradiation with plasma J in the rotated state is finish-ground by the grindstone unit 31 of the finish grinding unit 30, which rotates in the opposite direction to the wafer 1. In other respects, the grinding method according to this embodiment is similar to the grinding method according to the first embodiment.

[0079] In the grinding device of this embodiment, as in the first embodiment, a method for optimizing the conditions for irradiating plasma J by the pretreatment device 10 can be implemented, and as in the first embodiment, a method for optimizing the conditions for grinding by the grinding section 30 can be implemented.

[0080] As described above, the grinding device 200 according to this embodiment can provide the same functions and effects as the grinding device 100 according to the first embodiment.

[0081] 12 to 14, a grinding apparatus 300 according to the third embodiment will be described. The grinding apparatus 300 has first to fourth preprocessing apparatuses 61, 62, 63, and 64. As shown in FIG. 12, the grinding apparatus 300 according to this embodiment is similar to the grinding apparatus 100 according to the first embodiment, except that it has a plurality of preprocessing apparatuses (first to fourth preprocessing apparatuses 61, 62, 63, and 64) that are spaced apart from one another in the circumferential direction of the wafer 1.

[0082] 13 and 14, the pretreatment devices (first to fourth pretreatment devices 61 to 64) of the grinding apparatus 300 are generally configured similarly to the pretreatment device 10 of the grinding apparatus 100 of the first embodiment. These pretreatment devices (first to fourth pretreatment devices 61 to 64) have plasma generators 61a, 62a, 63a, and 64a that can irradiate the treatment target G with plasmas K1, K2, K3, and K4 to modify the treatment target G. Each of the plasma generators 61a to 64a also has a nozzle 61c, 62c, 63c, and 64c that can emit the plasmas K1 to K4 toward the outside along an irradiation axis 61b, 62b, 63b, and 64b.

[0083] 14, nozzles 61c-64c of plasma generators 61a-64a in the plurality of pretreatment devices (first to fourth pretreatment devices 61-64) are arranged offset from one another in the radial direction of the wafer 1 so that plasmas K1-K4 emitted from these devices can be irradiated onto the entire corners 3 of the outer circumferential portion 2 of the wafer 1 that face the nozzles 61c-64c. Such plasma generators 61a-64a may also be configured not to perform the raster scanning described above.

[0084] The grinding method using the grinding apparatus 300 according to this embodiment is similar to the grinding method using the grinding apparatus 100 according to the first embodiment, except that it uses a plurality of pre-processing devices (first to fourth pre-processing devices 61 to 64). The grinding apparatus 100 according to this embodiment can implement a method for optimizing the conditions for irradiating plasmas K1 to K4 by the plurality of pre-processing devices (first to fourth pre-processing devices 61 to 64), as in the first embodiment, and can also implement a method for optimizing the conditions for grinding by the grinding unit, as in the first embodiment.

[0085] 14 shows, as an example, a grinding unit including four pre-processing devices (first to fourth pre-processing devices 61 to 64), namely, a first and second pre-processing device 62, a third pre-processing device 63, and a fourth pre-processing device 64. However, the grinding device may have two, three, five or more pre-processing devices.

[0086] As described above, the grinding device 400 according to this embodiment can provide the same functions and effects as the grinding device 100 according to the first embodiment.

[0087] Furthermore, the grinding apparatus 400 according to this embodiment has a plurality of pretreatment devices (first to fourth pretreatment devices 61 to 64) that are spaced apart from one another in the circumferential direction of the wafer 1. Therefore, the entire processing target portion G can be efficiently softened by irradiating it with a plurality of plasmas K1 to K4.

[0088] The pre-processing devices (first to fourth pre-processing devices 61 to 64) and grinding device according to the fourth embodiment will be described below with reference to Fig. 15. The pre-processing devices (first to fourth pre-processing devices 61 to 64) of the grinding device according to this embodiment are the same as the pre-processing devices (first to fourth pre-processing devices 61 to 64) of the grinding device according to the third embodiment. The grinding device 400 according to this embodiment is the same as the grinding device 300 according to the third embodiment, except that it does not have the rough grinding unit 20. The grinding device may have two, three, five or more pre-treatment devices.

[0089] The grinding method using the grinding apparatus 400 according to this embodiment differs from the grinding method using the grinding apparatus 300 according to the third embodiment in that it does not include a step related to rough grinding and does not use the rough grinding unit 20. In this grinding method, plasmas K1 to K4 from plasma generators 61a to 64a of multiple pretreatment devices (first to fourth pretreatment devices 61 to 64) are irradiated onto the processing target G of the outer peripheral portion 2 of the wafer 1 in a rotated state, and then the outer peripheral portion 2 of the wafer 1 after being irradiated with the plasmas K1 to K4 in the rotated state is finish-ground by the grindstone unit 31 of the finish grinding unit 30, which rotates in the opposite direction to the wafer 1. In other respects, the grinding method according to this embodiment is similar to the grinding method according to the third embodiment.

[0090] In the grinding apparatus 400 of this embodiment, as in the third embodiment, a method can be implemented to optimize the conditions for irradiating plasma K1 to K4 by multiple pre-treatment devices (first to fourth pre-treatment devices 61 to 64), and as in the first embodiment, a method can be implemented to optimize the conditions for grinding by the finish grinding unit.

[0091] As described above, the grinding device 400 according to this embodiment can provide the same functions and effects as the grinding device 300 according to the third embodiment.

[0092] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and the present invention can be modified and changed based on the technical concept thereof. [Explanation of symbols]

[0093] 1...wafer, 1a...central axis, 2...periphery, 3...corner, G...processing target portion 10...pretreatment device, 10a...plasma generator, 10b...irradiation axis, 10c...nozzle, J...plasma 20... rough grinding section, 21... grindstone section, 22... drive section, 23... cutting depth adjustment section 30...finish grinding section, 31...grindstone section, 32...drive section, 33...cutting amount adjustment section 40... Swivel device, 41... Swivel mechanism, 42... Fixed part, 43... Drive part 50...control device, 51...arithmetic unit, 52...surface inspection device, 53...shape inspection device, 54...crystal inspection device 61...first pre-treatment device, 62...second pre-treatment device, 63...third pre-treatment device, 64...fourth pre-treatment device, 61a, 62a, 63a, 64a...plasma generators, 61b, 62b, 63b, 64b...irradiation axis, 61c, 62c, 63c, 64c...nozzles, K1 to K4...plasma 100, 200, 300, 400...Grinding equipment

Claims

1. A grinding apparatus comprising at least one plasma generator for applying plasma to at least a portion of a peripheral edge of a wafer before grinding the peripheral edge.

2. The plasma generator includes a plurality of plasma generators; each of the plurality of plasma generators has a nozzle for emitting plasma; 2. The grinding apparatus according to claim 1, wherein the nozzles of the plurality of plasma generators are arranged to direct plasma toward two corners of the outer periphery of the wafer in the thickness direction.

3. 3. The grinding apparatus according to claim 2, wherein the nozzles of the plurality of plasma generators are each tiltable.

4. a rotating device used to rotate the wafer about its central axis; a grinding unit including a grinding stone unit that grinds the outer peripheral portion of the wafer and a drive unit that rotates the grinding stone unit, 2. The grinding apparatus according to claim 1, wherein the plasma generator is capable of irradiating plasma onto a pretreatment target portion that moves in a circumferential direction of the wafer as the wafer rotates about a central axis of the wafer.

5. a control device; a calculation device capable of calculating at least one of an optimum condition for plasma irradiation by the plasma generator and an optimum condition for grinding by the grinding unit; Equipped with 5. The grinding device according to claim 4, wherein the control device is capable of controlling at least one of the plasma generator and the grinding unit so as to conform to at least one of the optimal conditions for the plasma irradiation and the optimal conditions for the grinding calculated by the arithmetic device.

6. a surface inspection device that can inspect the surface state of the wafer; the arithmetic unit is capable of calculating, as an optimum condition for the plasma irradiation, an optimum value of at least one of the power and diameter of the plasma and the rotation speed of the wafer based on the data of the surface state; 6. The grinding device according to claim 5, wherein the control device is capable of controlling the plasma generator and the turning device so as to conform to the optimum value.

7. a shape inspection device that can inspect the shape of the wafer and / or a crystal inspection device that can inspect the crystalline state of the wafer; the arithmetic unit is capable of calculating, as the optimum grinding condition, an optimum value of at least one of the cutting depth and rotation speed of the grinding stone unit and the rotation speed of the wafer based on at least one of the shape and the crystalline state, 6. The grinding device according to claim 5, wherein said control device is capable of controlling said grinding unit and said turning device so as to conform to said optimum value.

8. 5. The grinding apparatus according to claim 4, comprising a plurality of said plasma generators arranged at intervals in the circumferential direction of said wafer.

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