Grindstone and method

Abstract

This grindstone comprises a plurality of processing parts (11) that are arranged on a processing surface (10a) for polishing or grinding a wafer and that extend in a direction intersecting the processing surface (10a). The plurality of processing parts (11) are disposed at positions separated from each other in the circumferential direction (C) and the radial direction (R) of the processing surface (10a). The area of a processing region positioned on the processing surface (10a) of each of the plurality of processing parts (11) is set to 4 mm2 or less.

Description

Grinding stone and method

[0001] The present invention relates to grinding wheels and methods.

[0002] The surface plate for a surface polishing apparatus described in Patent Document 1 comprises a donut-shaped metal surface plate body, a plurality of polishing pellets made of diamond abrasive grains attached to the surface of the surface plate body in a desired arrangement pattern and spacing, and a synthetic resin that fills the gaps between each pellet.

[0003] The grinding wheel described in Patent Document 2 is constructed by arranging a large number of arc-shaped grinding wheel chips on the outer circumference of a metal disc.

[0004] Japanese Patent Application Publication No. 6-55459 Publication No. 6-73815

[0005] The surface plate and grinding wheel for the surface polishing apparatus described in Patent Documents 1 and 2 above had room for improvement in cutting performance when processing the workpiece. In particular, when the workpiece is a hard-to-machine material with high hardness, such as silicon carbide (SiC), the cutting performance tends to deteriorate, so there was a need to improve the cutting performance.

[0006] This invention has been made in view of the above circumstances, and aims to provide a whetstone that can improve sharpness.

[0007] (1) To achieve the above objective, the grinding wheel according to the first aspect of the present invention comprises a plurality of processing parts arranged on a processing surface for polishing or grinding a workpiece, extending in a direction intersecting the processing surface, wherein the plurality of processing parts are positioned at separate locations in the circumferential and radial directions of the processing surface, and the area of ​​the processing region located on the processing surface of each of the plurality of processing parts is 4 mm ２ It is set as follows:

[0008] (2) In the grinding wheel described in (1) above, the area of ​​the processing region is 0.05 mm ２ You may set it as described above.

[0009] (3) The grinding wheel described in (1) or (2) above may be configured such that the processing area is rectangular, and the longitudinal direction of the processing area is inclined with respect to the tangent direction of a virtual arc extending in the circumferential direction that passes through the processing area, and the radial direction.

[0010] (4) In the grinding wheel described in (3) above, the longitudinal direction of the processing area may be arranged in a direction that is inclined by an angle of inclination with respect to the tangential direction, and the angle of inclination may be set to 15° to 60°.

[0011] (5) In the grinding wheel described in (3) or (4) above, the plurality of processing parts may be arranged in a row with spacing in the direction along the longitudinal direction, and the plurality of processing parts arranged in a row may be arranged in multiple rows in the circumferential direction.

[0012] (6) In the grinding wheel described in any one of (1) to (5) above, the plurality of processing parts are arranged in a row with spacing in a direction inclined in the radial direction, the plurality of processing parts arranged in a row are arranged in multiple rows in the circumferential direction, the grinding wheel has connecting parts that connect the plurality of processing parts arranged in a row at the ends of the plurality of processing parts furthest from the processing surface and are integrally formed with the processing parts, the connecting parts and the plurality of processing parts connected by the connecting parts are configured as comb-shaped processing tips, and the grinding wheel has a holding part that holds the plurality of comb-shaped processing tips so as to be filled around the plurality of comb-shaped processing tips and the processing area is exposed on the processing surface.

[0013] (7) The grinding wheel described in any one of (1) to (6) above may be equipped with a holding portion that holds the plurality of processing portions so as to fill the periphery of the plurality of processing portions and expose the processing area to the processing surface, and the ratio of the area of ​​all the processing areas of the plurality of processing portions to the total area of ​​the processing surface may be set to 5% to 20%.

[0014] (8) The grinding wheel described in any one of (1) to (7) above includes a holding portion that is filled around the plurality of processing portions so that the processing area is exposed on the processing surface, and each of the plurality of processing portions may be in the shape of a rectangular plate that is long in the vertical direction perpendicular to the processing surface and short in the horizontal direction along the processing surface.

[0015] (9) In the grinding wheel described in any one of (1) to (8) above, each of the plurality of processing parts may be provided with a plurality of abrasive grains for polishing or grinding the workpiece, and a binder made of a metal that does not contain copper components for holding the plurality of abrasive grains.

[0016] (10) To achieve the above objective, a method relating to a second aspect of the present invention involves polishing or grinding the workpiece made of silicon carbide with a grinding wheel described in any one of (1) to (9) above.

[0017] (11) In the method described in (10) above, the processing area is rectangular, and the longitudinal direction of the processing area is arranged to be inclined with respect to the tangent direction of a virtual arc extending in the circumferential direction passing through the processing area and the radial direction, and the plurality of processing parts are arranged in a row with spacing along the longitudinal direction, and the plurality of processing parts arranged in a row are arranged in multiple rows in the circumferential direction, and are arranged so that they are in the direction of a first rotational direction in the circumferential direction as they move from the inside to the outside in the radial direction, and the method is the first processing The process may include the steps of: the control unit receiving an operation in which the user selects either the first processing mode or the second processing mode; and, if the control unit receives an operation in which the user has selected the first processing mode, the drive unit that rotates the grinding wheel in the first rotational direction to polish or grind the workpiece; and if the control unit receives an operation in which the user has selected the second processing mode, the drive unit that rotates the grinding wheel in the second rotational direction opposite to the first rotational direction in the circumferential direction to polish or grind the workpiece.

[0018] According to the present invention, the cutting performance can be improved.

[0019] The schematic diagram of a processing system according to an embodiment of the present invention. The bottom view of a grindstone according to an embodiment of the present invention. An enlarged view of the range 2b in FIG. 2A. An enlarged view of the range 2c in FIG. 2B. A cross-sectional view taken along line III-III in FIG. 2B. A plan view of a part of a grindstone according to an embodiment of the present invention. A plan view showing a grindstone and a wafer in a first processing mode according to an embodiment of the present invention. A plan view showing a grindstone and a wafer in a second processing mode according to an embodiment of the present invention. A graph showing the relationship between the load current value and the grinding ratio for each grindstone having a different area of the processing region according to an embodiment of the present invention. A perspective view of a grindstone according to a modified example of the present invention. A perspective view of a grindstone according to a comparative example.

[0020] A processing system including a grindstone according to an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the processing system 3 includes a grindstone rotating device 4, a wafer rotating device 5, a control unit 70, and an operation unit 75.

[0021] The wafer rotating device 5 rotates the wafer W about its axis while supporting it. The wafer rotating device 5 includes a table 51, a rotating shaft portion 52, and a motor 53. The table 51 is plate-shaped and chucks the wafer W on its upper surface facing the grindstone rotating device 4. A known method such as vacuum chucking or electrostatic chucking is adopted as the method for chucking the wafer W. The wafer W is a difficult-to-machine material having a new Mohs hardness of 13 or more, for example, SiC, and is a power semiconductor. The rotating shaft portion 52 is cylindrical about the rotating shaft C2 and is located at the center of the back surface of the upper surface of the table 51. The motor 53 rotates the rotating shaft portion 52 about the rotating shaft C2 under the control of the control unit 70. Thereby, the wafer W rotates together with the table 51 about the rotating shaft C2 passing through the center of the wafer W.

[0022] The grindstone rotating device 4 grinds the wafer W by bringing the grindstone 10, which will be described later, into contact with the wafer W chucked on the table 51 while rotating it about its axis. The grindstone rotating device 4 includes a grindstone unit 1, a grindstone holding portion 20, a rotating shaft portion 22, and a motor 23.

[0023] The grindstone holding part 20 is the part where the grindstone unit 1 is fixed. The rotating shaft part 22 has a columnar shape centered on the rotating shaft C1 and is located at the center of the upper surface of the grindstone holding part 20 (the back side of the surface facing the table 51). The rotating shaft C1 is parallel to the rotating shaft C2. The motor 23 rotates the rotating shaft part 22 around the rotating shaft C1 under the control of the control part 70. As a result, the grindstone unit 1 rotates together with the grindstone holding part 20 around the rotating shaft C1 passing through the center of the grindstone unit 1.

[0024] The control part 70 consists of a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). By supplying a load current to the motors 23 and 53 via a motor driver not shown, the wafer W together with the table 51 and the grindstone unit 1 together with the grindstone holding part 20 are rotated separately.

[0025] As shown in Fig. 2A, the grindstone unit 1 includes a grindstone 10 for processing the wafer W and a grindstone support part 18 fixed to the grindstone 10.

[0026] The grindstone support part 18 is made of metal and has an annular shape, and supports the grindstone 10 from its back surface (the surface opposite to the processing surface 10a). The inner peripheral surface of the grindstone support part 18 is located inside the inner peripheral surface of the grindstone 10 in the radial direction R.

[0027] The grindstone 10 has an annular shape. The shape of the cut surface cut along the radial direction R of the grindstone 10 is rectangular. The surface of the grindstone 10 facing the wafer W is the processing surface 10a for grinding the wafer W. The processing surface 10a has an annular planar shape. Note that the grindstone 10 may have a disc shape.

[0028] As shown in Figs. 2A - C and Fig. 3, the grindstone 10 includes a plurality of comb - tooth processing tips 14 and a holding part 19.

[0029] The comb-tooth machining tip 14 has a flat, comb-like shape. As shown in Figure 3, the comb-tooth machining tip 14 comprises a plurality of machining parts 11 and a connecting part 13. Openings 14h are formed between the plurality of machining parts 11, opening toward the machining surface 10a. In this example, six openings 14h are arranged between seven machining parts 11. Each of the plurality of machining parts 11 is rectangular in shape and is arranged in a row with a gap B equal to the opening 14h. The opposing sides of two adjacent machining parts 11 face each other with the gap B in between. Each machining part 11 is rectangular in shape, longer in the vertical direction perpendicular to the machining surface 10a (up and down direction in Figure 3) and shorter in the horizontal direction where the machining parts 11 are arranged (left and right direction in Figure 3).

[0030] The connecting portion 13 connects multiple processing portions 11 at the ends opposite to the processed surfaces 10a of the processing portions 11 (the upper ends in Figure 3). The connecting portion 13 is a rectangle that extends across the multiple processing portions 11 arranged in a row. The length of the processing portion 11 in the vertical direction is longer than the length of the connecting portion 13 in the vertical direction. The lateral end 13a of the connecting portion 13 protrudes laterally outward from the processing portion 11 closest to this end 13a. As a result, the end 13a catches on the holding portion 19, which will be described later, and the comb-tooth processing tip 14 is stably held in the holding portion 19.

[0031] The comb-tooth machining tip 14 comprises a plurality of abrasive grains 15 and a binder 16, as shown in an enlarged view at the bottom of Figure 3. The plurality of abrasive grains 15 are distributed within the binder 16. The abrasive grains 15 are, for example, diamond. However, the abrasive grains 15 are not limited to diamond; they may also be cubic boron nitride (CBN) abrasive grains, or a mixture of CBN abrasive grains and diamond. Furthermore, the plurality of abrasive grains 15 may be SiC, or fused alumina (Al ２ O ３), or a mixture thereof. The binder 16 holds a plurality of abrasive grains 15 inside. The binder 16 is formed from a metal such as nickel, iron, aluminum, or aluminum alloy, a resin such as phenol resin or epoxy resin, or a ceramic such as vitrified. Preferably, the binder 16 is formed from a material that does not contain copper components (for example, nickel). In comparison, if the binder contains copper components, the copper components tend to cause corrosion or contamination of the wafer. Therefore, by forming the binder 16 from a material that does not contain copper components, corrosion or contamination of the wafer W can be suppressed.

[0032] As shown in Figure 2A, the multiple machining parts 11 are arranged in a single row in the shape of a dashed line, and this single row is arranged across multiple rows L1 to Ln (where n is any natural number). All of the machining parts 11 in a single row are arranged on the same virtual plane perpendicular to the machining surface 10a. The multiple rows L1 to Ln are arranged in the circumferential direction C of the machining surface 10a with a constant spacing A. The multiple machining parts 11 in any one of the multiple rows L1 to Ln partially overlap the multiple machining parts 11 in an adjacent row in the circumferential direction C when viewed from the radial direction R (70% to 90% of the total length of the row). The spacing A at the outer ends of each row L1 to Ln in the radial direction R is set to 3 mm to 10 mm, for example, about 5 mm (including ±1 mm). In this example, the number of rows L1 to Ln is 152. Note that the number of rows L1 to Ln is not limited to this and can be changed as appropriate. In other words, the multiple processing units 11 are distributed and arranged on the processing surface 10a.

[0033] As shown in Figure 2B, the multiple machined parts 11 in each row L1 to Ln are arranged in a single row in a direction extending at an inclination angle θ with respect to the tangential direction T. The tangential direction T is the direction of the tangent to the virtual arc extending in the circumferential direction C that passes through the machined parts 11. The inclination angle θ is set to an angle other than 90° and 0° with respect to the tangential direction T. The inclination angle θ is set to an acute angle. The inclination angle θ is the value obtained by subtracting the angle formed by the row direction of the machined parts 11 in a single row and the radial direction R intersecting that row direction from 90°.

[0034] The inclination angle θ is set within the range of 15° to 60°, 20° to 40°, 25° to 35°, or 28° to 32°. The inclination angle θ is preferably set within the range of 29° to 31°, about 30° (including ±1°). The upper and lower limits of each of the above numerical ranges of the inclination angle θ can be appropriately combined. When the inclination angle θ is less than 15° (for example, 0°), the processing portion 11 is likely to wear and is likely to be damaged. On the other hand, when the inclination angle θ exceeds 60° (for example, 90°), the grinding resistance of the grindstone 10 increases and the cutting performance deteriorates. From such a viewpoint, it is preferable that the inclination angle θ is set at least within the range of 15° to 60°.

[0035] As shown in FIG. 2C, the area of the processing region 10b exposed on the processing surface 10a of each processing portion 11 is, for example, 4 mm ２ or less. When there is variation in the area of the processing region 10b for each processing portion 11, the average value is taken. This average value is obtained by a trimmed mean excluding 5% each of the upper and lower portions. The area of the processing region 10b is measured, for example, by photographing the processing surface 10a with a camera, extracting the processing region 10b from the photographed image by image analysis processing, and calculating the area. The lower limit value of the area of the processing region 10b is the minimum achievable area of the processing region 10b. In practice, the area of the processing region 10b is, for example, 0.05 mm ２ or more. When the area of the processing region 10b is 0.05 mm ２ or more, for example, the width W (the thickness of the processing portion 11) of the processing region 10b is 0.05 mm and the length L of the processing region 10b is 1 mm. The inventors of the present application have realized the production of the grindstone 10 with the area of the processing region 10b being 0.05 mm ２ or more. As described above, the area of each processing region 10b is set within the range of 0.05 mm ２ to 4 mm ２ or more. These exemplified upper and lower limit values may be appropriately combined. The technical significance of the upper limit value (4 mm ２ ) of the area of the processing region 10b will be described in detail later.

[0036] In the configuration of Patent Document 1, the diamond pellet is a disc shape with a diameter of 20 mm, so the area of ​​the diamond pellet is 314 mm². ２ As a result, the values ​​do not fall within the numerical range described above in this embodiment. Therefore, the surface plate for the planar polishing apparatus in Patent Document 1 results in a large motor load current and a decrease in cutting performance. This problem is particularly noticeable when processing high-hardness wafers.

[0037] As shown in Figures 2C and 3, the processing area 10b of one processing section 11 is rectangular. This rectangle can be any shape that is long in a predetermined direction, and may include, for example, a rectangle whose short or long side is curved or has irregularities. The width W (thickness of the processing section 11) of the processing area 10b in the short direction is set to, for example, 0.1 mm to 1 mm, preferably 0.1 mm to 0.8 mm. The length L of the processing area 10b in the longitudinal direction is set to 0.2 mm to 10 mm, 1 mm to 4 mm, 2 mm to 4 mm, or 1.5 mm to 2.5 mm. The length L is preferably set to 1.9 mm to 2.1 mm, approximately 2 mm (including ±0.1 mm). The distance B between two processing sections 11 arranged in a row is set to 1.5 mm to 2 mm.

[0038] Each processing section 11 grinds the wafer W while being cut. All processing sections 11 of the grinding wheel 10 are formed to have the same shape and size. The ratio of the area of ​​the multiple processing sections 11 (all processing areas 10b) to the processing surface 10a is set to, for example, 5% to 20%, preferably 10% to 15%. This makes it possible to achieve both sharpness and lifespan of the grinding wheel 10.

[0039] As shown in Figure 7, the comparative example grinding wheel 310 has multiple processing sections 311 that are curved in the circumferential direction C, arranged at intervals in the circumferential direction C. In the grinding wheel 310, there are no multiple processing sections 311 arranged in the radial direction R. Also, the area of ​​the processing region 311b of each processing section 311 is larger than the area of ​​the processing region 10b in this embodiment. In this grinding wheel 310, compared to the grinding wheel 10 of this embodiment, the area of ​​the processing region 311b is larger and the number of processing regions 311b is smaller, so the processing resistance is larger, the load current of the motor 23 is larger, and the cutting performance is reduced. In this respect, in the grinding wheel 10 of this embodiment, the area of ​​the processing region 10b is smaller and the number of processing regions 10b is larger, so the processing resistance is smaller, the load current of the motor 23 is smaller, and the cutting performance is better. In particular, the smaller the area of ​​the processing region 10b, the easier it is to cut into the wafer W, as will be described in detail later, and the cutting performance is improved. Furthermore, as the number of processing areas 10b increases, the number of corners in the processing areas 10b also increases, which further improves the sharpness of the grinding wheel 10.

[0040] As shown in Figures 2A and 3, the holding portion 19 is formed over the entire area of ​​the processed surface 10a and holds a plurality of processed portions 11. The holding portion 19 fills the area around each processed portion 11. Each processed portion 11 is embedded in the holding portion 19 with its tip exposed to the processed surface 10a. The holding portion 19 is formed of a material and shape that is more elastically deformable by external forces than the processed portion 11 and more easily worn than the processed portion 11 during processing. As a result, during the processing of the wafer W, the holding portion 19 wears more than the processed portion 11, and the tip of the processed portion 11 remains protruding beyond the holding portion 19. Therefore, sharpening of the grinding wheel 10 is unnecessary. The holding portion 19 is formed of a metal such as nickel, iron, aluminum, or aluminum alloy, a resin such as phenol resin or epoxy resin, or a ceramic such as vitrified. The holding portion 19 may be formed so that fluid cannot pass through it, or it may be formed of a porous material that allows fluid to pass through. For example, both the retaining portion 19 and the binder 16 may be formed from a ceramic such as a vitrified material, with the retaining portion 19 being made of a porous material and the binder 16 being made of a non-porous material.

[0041] As shown in Figure 4A, the multiple machining sections 11 arranged in a row are inclined in the counterclockwise direction CCW of the circumferential direction C as they move from the inside to the outside in the radial direction R of the machining surface 10a. As shown in Figures 4B and 4C, the clockwise direction CW and the counterclockwise direction CCW indicate the direction of rotation when the grinding wheel 10 is viewed from above, that is, when the grinding wheel 10 is viewed from above.

[0042] The grinding wheel 10 is configured to be selectively used in either of two modes, depending on its rotation direction: a first processing mode in which it moves on the wafer W in a manner that "cuts" the wafer W with each row of processing parts 11, as shown in the cutting direction A1 of Figure 4A, or a second processing mode in which it moves on the wafer W in a manner that "scrapes" the wafer W with each row of processing parts 11, as shown in the scraping direction A2. The cutting direction A1 is the direction in which the rows of processing parts 11 are arranged, and the scraping direction A2 is the direction that intersects the cutting direction A1 on the processed surface 10a.

[0043] First, a first processing method using the grinding wheel 10 will be described. As shown in Figure 4B, in the first processing method, the grinding wheel 10 and the wafer W are rotated in opposite directions in the circumferential direction C. Specifically, the grinding wheel 10 is rotated counterclockwise (CCW), and the wafer W is rotated clockwise (CW). As a result, the processing part 11 enters the upper surface of the wafer W from the cutting direction A1, and since the cutting direction A1 and the rotation direction of the wafer W are opposite, the relative speed of the grinding wheel 10 and the wafer W becomes high. In this first processing method, since the processing part 11 of each row moves on the wafer W in a way that "cuts" the wafer W, the processing resistance of the grinding wheel 10 is low and the cutting performance is good, but the amount of wear is high. The first processing method is also called up-cutting.

[0044] Next, a second processing method using the grinding wheel 10 will be described. As shown in Figure 4C, in the second processing method, the grinding wheel 10 and the wafer W are rotated in the same direction in the circumferential direction C. Specifically, both the grinding wheel 10 and the wafer W are rotated in the clockwise direction CW. As a result, each processing part 11 enters the upper surface of the wafer W from the scraping direction A2, and because the rotation direction of the grinding wheel 10 and the wafer W is the same, the relative speed between the grinding wheel 10 and the wafer W becomes low. In this second processing method, the dynamic friction force between each processing part 11 and the wafer W becomes large, so the strong contact of a part of each processing part 11 with the wafer W is suppressed, and the amount of wear on the grinding wheel 10 can be reduced, but the cutting performance decreases. This second processing method is suitable for processing wafers W that are prone to warping and edge cracking. The second processing method is also called down cutting.

[0045] As described above, the first and second processing modes each have their own advantages and disadvantages, so the first and second processing modes can be used interchangeably depending on the required processing. For example, the first processing mode, which has a faster processing speed, can be used for grinding ordinary wafers W, while the second processing mode, which results in softer contact between the processing unit 11 and the wafer W, can be used for grinding wafers W that are prone to deformation or breakage. Furthermore, the process is not limited to this; the wafer W may be ground first using the first processing mode, and then ground using the second processing mode. The control unit 70 accepts an operation by the user to select either the first or second processing mode in response to an operation by the operation unit 75. When the control unit 70 receives an operation to select the first processing mode, it rotates the grinding wheel 10 counterclockwise (CCW) and the wafer W clockwise (CW). When the control unit 70 receives an operation to select the second processing mode, it rotates both the grinding wheel 10 and the wafer W clockwise (CW). In addition to this example, the control unit 70 may grind the wafer W in the second processing mode after grinding the wafer W in the first processing mode.

[0046] (Experimental Results) The inventors of the present invention conducted an experiment to measure the load current value of the motor 23 and the grinding ratio when the area of ​​the processing region 10b of the processing section 11 was changed for the grinding wheel 10, and the experimental results are summarized in the graph in Figure 5. In this experiment, the wafer W was ground using the first to fifth grinding wheels 101 to 105, which are the grinding wheels 10 of this embodiment, and the sixth and seventh grinding wheels 316 and 317, which are the grinding wheels 310 of the comparative example. In the graph in Figure 5, the relationship between the load current value (current value of the motor 23) and the grinding ratio for each grinding wheel 101 to 105, 316, and 317 is shown by graph lines E1 to E7. The first grinding wheel 101 corresponds to graph line E1, the second grinding wheel 102 corresponds to graph line E2, the third grinding wheel 103 corresponds to graph line E3, the fourth grinding wheel 104 corresponds to graph line E4, the fifth grinding wheel 105 corresponds to graph line E5, the sixth grinding wheel 316 corresponds to graph line E6, and the seventh grinding wheel 317 corresponds to graph line E7. The grinding ratio is the ratio obtained by dividing the volume of the grinding wheel worn down by the volume of the wafer that was ground.

[0047] The area of ​​each processing region 10b of the first grinding wheel 101 is 0.3 mm². ２ The width W is 0.1 mm and the length L is 3 mm. The area of ​​each processing region 10b of the second grinding wheel 102 is 0.45 mm². ２ The width W is 0.15 mm and the length L is 3 mm. The area of ​​each processing region 10b of the third grinding wheel 103 is 1 mm ２ The width W is 0.5 mm and the length L is 2 mm. The area of ​​each processing region 10b of the fourth grinding wheel 104 is 3.2 mm². ２ The width W is 0.8 mm and the length L is 4 mm. The area of ​​each processing region 10b of the fifth grinding wheel 105 is 3.6 mm². ２ The width W is 0.8 mm and the length L is 4.5 mm. The area of ​​each processing region 10b of the sixth grinding wheel 316 is 9 mm². ２ The radial length (thickness) of R is 3 mm, and the circumferential length C is 3 mm. The area of ​​each machining region 10b of the seventh grinding wheel 317 is 18 mm². ２ The radial length (thickness) R is 3 mm, and the circumferential length C is 6 mm.

[0048] The configuration and experimental conditions for the first to fifth grinding wheels 101 to 105 are shown below. • Inner diameter of grinding wheel: 230 mm • Outer diameter of grinding wheel: 250 mm • Total surface area of ​​the machined surface: 7540 mm² ２ - Ratio of the total machining area to the total surface area: 5-20% - Spacing between rows of machining parts: 3-10 mm - Number of machining parts per row: 1-6 - Number of rows of machining parts arranged circumferentially: 150-200 - Wafer material: SiC - Grinding wheel rotation speed: 1250 min －１ (16.3m / S), 1500min －１ (19.6m / S), 1800min －１ (23.6m / S), 2150min －１ (28.1m / S), 2500min －１ (32.7m / S), 3000min －１ (39.3 m / s) • Wafer rotation speed 301 min －１ ・Processing speed 0.3μm / S

[0049] The method for drawing the graph line E1 corresponding to the first grinding wheel 101 will be explained. The wafer W is ground by rotating the first grinding wheel 101 at a rotation speed of 16.3 m / s, and the average load current value and grinding ratio at this time are calculated and plotted as P1 on the graph in Figure 5. Next, the wafer W is ground by rotating the first grinding wheel 101 at a rotation speed of 23.6 m / s, and the average load current value and grinding ratio at this time are calculated and plotted as P2 on the graph in Figure 5. Next, the wafer W is ground by rotating the first grinding wheel 101 at a rotation speed of 28.1 m / s, and the average load current value and grinding ratio at this time are calculated and plotted as P3 on the graph in Figure 5. Next, the wafer W is ground by rotating the first grinding wheel 101 at a rotation speed of 32.7 m / s, and the average load current value and grinding ratio at this time are calculated and plotted as P4 on the graph in Figure 5. Next, the first grinding wheel 101 is rotated at a speed of 39.3 m / s to grind the wafer W. The average load current value and grinding ratio at this time are calculated and plotted as P5 on the graph in Figure 5. Based on these plots P1 to P5, the graph line E1 is drawn.

[0050] Similarly, for the other grinding wheels 102-105, 316, and 317, plots were made by grinding the wafer W while varying the grinding wheel rotation speed, and graph lines E2-E7 were drawn based on these plots. Note that the graphs do not show plots for all grinding wheel rotation speeds; some plots for certain grinding wheel rotation speeds have been omitted to make the relationship between load current value and grinding ratio easier to understand. For example, in graph lines E6 and E7, the relationship between load current value and grinding ratio is clear from two plots in each, so the other plots have been omitted.

[0051] The following findings were obtained from the graph in Figure 5. In the sixth and seventh grinding wheels 316 and 317, as shown by graph lines E6 and E7, it can be seen that when the grinding wheel rotation speed is increased, the load current value increases, but the grinding ratio hardly increases. Possible reasons for this include frictional heat between the processing part and the wafer W, and the processing part sliding against the wafer W without biting into it. On the other hand, in the first to fifth grinding wheels 101 to 105, as shown by graph lines E1 to E5, when the grinding wheel rotation speed is increased, the load current value and the grinding ratio increase. Therefore, it can be seen that the first to fifth grinding wheels 101 to 105 are able to grind the SiC wafer W smoothly. In the first to fifth grinding wheels 101 to 105, compared to the sixth and seventh grinding wheels 316 and 317, the frictional heat between the processing part and the wafer W is smaller, and it is thought that the processing part bites into the wafer W more easily and slippage is suppressed. Furthermore, it can be seen that the smaller the area of ​​the processing region 10b, the greater the grinding ratio can be increased with a smaller increase in the load current value. Therefore, it can be said that the area of ​​the processing region 10b is the factor that most strongly influences whether or not the wafer W can be ground.

[0052] Based on the above findings, the upper limit of the area of ​​the processing region 10b can be set as follows. Of the first to fifth grinding wheels 101 to 105 in this embodiment, the fifth grinding wheel 105 has the largest area of ​​the processing region 10b. Therefore, the area of ​​the processing region 10b in the fifth grinding wheel 105 is 3.6 mm. ２ 4 mm, rounded to the nearest tenth. ２ This was set as the upper limit of the area of ​​the processing region 10b for smoothly grinding the wafer W.

[0053] The above findings are novel and cannot be derived from the common technical knowledge in this field. Conventionally, it was thought that the smaller the area of ​​the processing region, the better the cutting performance, but the more easily the processed part wore down and the shorter the lifespan. However, when grinding a SiC wafer W with the first to fifth grinding wheels 101 to 105, a new finding was obtained that the smaller the area of ​​the processing region, the higher the grinding ratio can be increased with less current, resulting in better cutting performance and a longer lifespan because the processed part is less prone to wear due to the higher grinding ratio. Furthermore, it was found that the slope of the graph lines E1 to E7 increases as the area of ​​the processing region decreases. Here, the slope of graph line E7 is approximately 28, because when the load current value increases by 1A, the grinding ratio increases by approximately 28. Therefore, the area of ​​the processing region may be set so that the slope of the graph line is 28 or more, or 25 or more.

[0054] Each of the processing sections 11 of the first and second grinding wheels 101 and 102 is configured as an electroplated grinding wheel in which abrasive grains are fixed to a plating layer. That is, the binder 16 of each of the processing sections 11 of the first and second grinding wheels 101 and 102 is made of metal. Each of the processing sections 11 of the third to fifth grinding wheels 103 to 105 has abrasive grains fixed to vitrified material. That is, the binder 16 of each of the processing sections 11 of the third to fifth grinding wheels 103 to 105 is made of vitrified material. Because the binder 16 is made of a metal with a higher thermal conductivity than vitrified material, frictional heat between the processing section 11 and the wafer W is more easily dissipated, thereby reducing thermal energy loss and allowing the grinding ratio to be increased with a lower current value.

[0055] (Effects) The embodiment described above provides the following effects: (1) The grinding wheel 10 is arranged on a processing surface 10a for polishing or grinding a wafer W, which is an example of a workpiece, and has a plurality of processing parts 11 that extend in a direction intersecting the processing surface 10a. The plurality of processing parts 11 are arranged at separate positions in the circumferential direction C and the radial direction R of the processing surface 10a. The area of ​​the processing region 10b located on the processing surface 10a of each of the plurality of processing parts 11 is 4 mm ２ The following settings are configured. With this configuration, as described above, the sharpness of the whetstone 10 can be improved.

[0056] (2) The area of ​​the processing region 10b is 0.05 mm² ２ The settings are as described above. With this configuration, the sharpness of the whetstone 10 can be improved as described above.

[0057] (3) The machining area 10b of each machining section 11 is rectangular, and the longitudinal direction of the machining area 10b is inclined with respect to the tangential direction T and the radial direction R of a virtual arc extending in the circumferential direction C that passes through the machining area 10b. For example, in the first comparative example, in a configuration in which the machining area 10b extends in the tangential direction T or the circumferential direction C, the machining section 11 is prone to wear and damage. On the other hand, in the second comparative example, in a configuration in which the machining area 10b extends in the radial direction R, the machining resistance of the grinding wheel 10 increases, and the cutting performance decreases. With the above configuration, the disadvantages of the first and second comparative examples described above can be mitigated, and a grinding wheel 10 with a good balance between lifespan and cutting performance can be realized. Furthermore, the cutting performance is ensured by the numerical limitation of the area as described above. In addition, since the machining area 10b is rectangular and not curved, it is easy to manufacture.

[0058] (4) The longitudinal direction of the processing area 10b of each processing section 11 is arranged to be inclined by an inclination angle θ with respect to the tangential direction T, and the inclination angle θ is set to 15° to 60°. With this configuration, the disadvantages of the first comparative example and the second comparative example described above can be reduced.

[0059] (5) The multiple processing sections 11 are arranged in a row with spacing B along the inclination angle θ with respect to the tangential direction T. The multiple processing sections 11 arranged in a row are arranged in multiple rows L1 to Ln in the circumferential direction C. With this configuration, the number of corners of the processing section 11 that cut into the wafer W can be increased, and the cutting performance of the grinding wheel 10 can be improved. In particular, since cutting into SiC is more difficult than cutting into silicon (Si), processing becomes easier when the wafer W is SiC.

[0060] (6) The processing area 10b is rectangular. The length L in the longitudinal direction of the processing area 10b is set to 1 mm to 4 mm, and the width W, which is the length in the transverse direction of the processing area 10b, is set to 0.1 mm to 1 mm. In this case, the area of ​​the processing area 10b is 0.1 mm². ２ ~4mm ２ This is the setting. This configuration makes it possible to improve the sharpness of the whetstone 10.

[0061] (7) The multiple processing sections 11 are arranged in a row with spacing in a direction inclined in the radial direction R. The multiple processing sections 11 arranged in a row are arranged in multiple rows L1 to Ln in the circumferential direction C. The grinding wheel 10 has connecting sections 13 which are integrally formed from the same material as the processing sections 11 and connect the multiple processing sections 11 arranged in a row at the ends furthest from the processed surfaces 10a of the multiple processing sections 11. The connecting sections 13 and the multiple processing sections 11 connected by the connecting sections 13 are configured as comb-tooth processing tips 14 which are in the shape of comb teeth plates. The grinding wheel 10 has a holding section 19 which holds the multiple comb-tooth processing tips 14 so that the processing areas 10b of the multiple processing sections 11 are exposed to the processed surfaces 10a. With this configuration, the processing sections 11 can be arranged in a row easily and with high positional accuracy by filling the holding section 19 around the multiple comb-tooth processing tips 14. This makes it easier to manufacture the grinding wheel 10.

[0062] (8) The ratio of the area of ​​all processing areas 10b of the multiple processing parts 11 to the total area of ​​the processing surface 10a is set to 5% to 20%. This configuration makes it possible to achieve both sharpness and lifespan of the grinding wheel 10.

[0063] (9) The multiple processing units 11 arranged in a row are arranged so that as they move from the inside to the outside in the radial direction R, they move in the counterclockwise direction CCW, which is an example of the first rotation direction in the circumferential direction C. The method of polishing or grinding the wafer W with the grinding wheel 10 includes the steps of: the control unit 70 receiving an operation in which the user selects either the first processing mode or the second processing mode; if the control unit 70 receives an operation in which the first processing mode has been selected, the grinding wheel 10 is rotated in the counterclockwise direction CCW via a motor 23, which is an example of a drive unit for rotating the grinding wheel 10, to polish or grind the wafer W; and if the control unit 70 receives an operation in which the second processing mode has been selected, the grinding wheel 10 is rotated in the clockwise direction CW, which is an example of the second rotation direction in the circumferential direction opposite to the counterclockwise direction CCW, via the motor 23, to polish or grind the wafer W. With this configuration, as described above, the first and second processing modes have different advantages and disadvantages, so the first and second processing modes can be used interchangeably depending on the required processing.

[0064] (10) Each processing section 11 is a rectangular plate shape that is long in the vertical direction perpendicular to the processing surface 10a and short in the horizontal direction along the processing surface 10a. With this configuration, by making the length of the processing section 11 in the vertical direction longer than the length in the horizontal direction, the life of the processing section 11 when it wears down can be extended, and by making the length of the processing section 11 in the horizontal direction shorter than the length in the vertical direction, the area of ​​the processing region 10b can be reduced and the cutting performance can be improved. Even if the processing section 11 is elongated vertically in this way, since the processing section 11 is supported by the holding section 19, elastic deformation of the processing section 11 due to contact with the wafer W is suppressed, and stable processing is possible.

[0065] (11) Each processing unit 11 comprises a plurality of abrasive grains 15 for polishing or grinding the wafer W, and a binder 16 made of a metal that does not contain copper to hold the plurality of abrasive grains 15. With this configuration, the binder 16 made of metal makes it easier to dissipate frictional heat between the processing unit 11 and the wafer W even if the area of ​​the processing region 10b is small, thereby increasing the grinding ratio with a small current and improving the cutting performance. In addition, since the binder 16 is made of a material that does not contain copper, corrosion or contamination of the wafer W can be suppressed.

[0066] The present invention is not limited to the embodiments and drawings described above. Modifications (including the deletion of components) can be made as appropriate without altering the essence of the invention. An example of a modification is described below.

[0067] (Modification) In the above embodiment, each processing part 11 was perpendicular to the processing surface 10a, but it may be inclined with respect to the processing surface 10a. Also, the processing part 11 does not have to contain a plurality of abrasive grains 15. In this case, the processing part 11 is made of a metal such as cemented carbide. In the above embodiment, the connecting part 13 may be omitted. In this case, all the processing parts 11 are made as separate parts.

[0068] In the above embodiment, seven processing units 11 were arranged in a row, but it is sufficient for multiple processing units 11 to be arranged in a row; for example, two to six or seven or more processing units 11 may be arranged.

[0069] In the above embodiment, the grinding wheel 10 was grinding the wafer W, but it is not limited to grinding; the wafer W may also be polished. In the above embodiment, the wafer W was SiC, but it may also be gallium nitride (GaN), which is a difficult material to process other than SiC, or it may be ceramics, silicon, LED (Light Emitting Diode) substrate, heat dissipation substrate, alumina, sapphire, or metal.

[0070] In the above embodiment, the abrasive grains 15 may be contained only in the processing portion 11 of the comb-tooth processing tip 14, and the abrasive grains 15 may not be contained in the connecting portion 13. Also, the abrasive grain content of the processing portion 11 may be higher than that of the connecting portion 13. In the above embodiment, the processed surface 10a may be circular.

[0071] The area of ​​the processing region 10b is 4 mm². ２ Not limited to the following, approximately 3.6 mm ２ (±0.1mm) ２ (including) approximately 3.2 mm ２ (±0.1mm) ２ (including) approximately 1.0 mm ２ (±0.1mm) ２ (including) approximately 0.45 mm ２ (±0.05mm) ２ (including) or less, or approximately 0.35 mm ２ (±0.05mm) ２ It may be set to less than or equal to (including). Also, the lower limit of the area of ​​the processing region 10b is 0.05 mm ２ It is not limited to this, and can be changed as appropriate, for example, 0.1 mm ２ or 0.2 mm ２ It can also be used as a setting.

[0072] In the above embodiment, in the first processing mode, the grinding wheel 10 and the wafer W were rotated in opposite directions in the circumferential direction C, but they may be rotated in the same direction. Also, in the second processing mode, the grinding wheel 10 and the wafer W were rotated in the same direction, but they may be rotated in opposite directions. Furthermore, it is not necessary for either the grinding wheel 10 or the wafer W to rotate. The shape of the processing area 10b is not limited to a rectangle, but may be a square, a trapezoid, or other polygon, or it may be circular or elliptical.

[0073] In the above embodiment, the multiple processing sections 11 arranged in a row were inclined in the counterclockwise direction CCW of the circumferential direction C as they moved from the inside to the outside in the radial direction R of the processing surface 10a, but they may also be inclined in the clockwise direction CW.

[0074] In the above embodiment, the area of ​​the processing region 10b is at least 4 mm ２ It was set to the following, but 4mm ２ It may be set to a greater than or equal to a certain value. In the above embodiment, the inclination angle θ was set to at least within the range of 15° to 60°, but it may be set outside this range. For example, the processed portion 11 may extend along the radial direction R or the circumferential direction C.

[0075] In the above embodiment, the grinding wheel 10 performed machining on its bottom surface. However, the invention is not limited to this, and as shown in Figure 6, the cylindrical grinding wheel 210 may be configured to perform machining on its outer circumferential surface, which becomes the machining surface 210a. In this case, the multiple machining sections 11 extend in a direction perpendicular to the cylindrical machining surface 210a and are arranged in a single row in a direction inclined with respect to the rotation axis C1 and the circumferential direction C of the grinding wheel 210. The multiple machining sections 11 arranged in a single row are then arranged in multiple rows with spacing in the circumferential direction C. The grinding wheel 210 has the same configuration as in the above embodiment, except that the position of the machining surface 210a is different. Therefore, even with this configuration, for example, the area of ​​the machining region exposed on the machining surface 210a of the machining section 11, and the inclination angle of the row of machining sections 11 are set in the same way as in the above embodiment, and the same effects and advantages as in the above embodiment can be obtained.

[0076] The above embodiments disclose, for example, the technical ideas described in the following appendices 1 to 4. Note that appendices 1 to 4 are not intended to limit the present invention in any way.

[0077] (Note 1) A grinding wheel comprising a plurality of processing sections arranged on a processing surface for polishing or grinding a workpiece, extending in a direction intersecting the processing surface, wherein the plurality of processing sections are arranged at dispersed positions on the processing surface, and the processing area of ​​each processing section is rectangular, and the longitudinal direction of the processing area is inclined with respect to the tangent direction of a virtual arc extending in the circumferential direction of the processing surface passing through the processing area, and the radial direction of the processing surface.

[0078] (Note 2) The grinding wheel as described in Note 1, wherein the longitudinal direction of the processing area of ​​each processing part is arranged to be inclined by an angle of inclination with respect to the tangential direction, the plurality of processing parts are arranged in a row with spacing along the angle of inclination, and the plurality of processing parts arranged in a row are arranged in multiple rows in the circumferential direction.

[0079] (Note 3) A grinding wheel comprising: a plurality of processing sections arranged on a processing surface for polishing or grinding a workpiece, extending in a direction intersecting the processing surface; and connecting sections made of the same material as the processing sections, connecting the plurality of processing sections at the ends of the plurality of processing sections furthest from the processing surface, wherein the connecting sections and the plurality of processing sections arranged in a row connected by the connecting sections are configured as comb-shaped cutting tips.

[0080] (Note 4) A cylindrical or cylindrical grinding wheel having its outer surface as the processing surface, comprising a plurality of processing parts arranged on the processing surface for polishing or grinding a workpiece, and extending in a direction intersecting the processing surface, wherein the plurality of processing parts are positioned at a distance from each other in the circumferential direction of the processing surface and in the direction of the rotation axis of the grinding wheel.

[0081] This invention allows for various embodiments and modifications without departing from the broad spirit and scope of the invention. Furthermore, the embodiments described above are for illustrative purposes only and do not limit the scope of the invention. In other words, the scope of the invention is indicated by the claims, not by the embodiments. Various modifications made within the scope of the claims and the equivalent scope of the meaning of the invention are considered to be within the scope of this invention.

[0082] This application is based on Japanese Patent Application No. 2024-190262, filed on 30 October 2024. The entire specification, claims, and drawings of Japanese Patent Application No. 2024-190262 are incorporated herein by reference.

[0083] 1...Grinding wheel unit, 3...Processing system, 4...Grinding wheel rotating device, 5...Wafer rotating device, 10, 210...Grinding wheels, 101-105...First to fifth grinding wheels, 316, 317...Sixth and seventh grinding wheels, 10a, 210a...Processing surface, 10b, 311b...Processing area, 11, 311...Processing section, 13...Connecting section, 13a...End section, 14...Comb-tooth processing tip, 14h...Opening, 15...Abrasive grains, 16...Bonding material, 18...Grinding wheel support section ,19...Holding part, 20...Grinding wheel holding part, 22, 52...Rotating shaft part, 23, 53...Motor, 51...Table, 70...Control unit, 75...Operating unit, 310...Grinding wheel, θ...Inclination angle, A, B...Spacing, A1...Cutting direction, A2...Scraping direction, C...Circumferential direction, CW...Turning direction, CCW...Counterclockwise direction, C1, C2...Rotation axis, E1 to E7...Graph lines, R...Radial direction, T...Tangential direction, W...Wafer, L1 to Ln...Row

Claims

1. The machine comprises a plurality of machining sections arranged on a machining surface for polishing or grinding a workpiece, extending in a direction intersecting the machining surface, wherein the plurality of machining sections are positioned at separate locations in the circumferential and radial directions of the machining surface, and the area of ​​the machining region located on the machining surface of each of the plurality of machining sections is 4 mm². ２ The following whetstones are set.

2. The area of ​​the processing region is 0.05 mm². ２ The grinding wheel according to claim 1, as set above.

3. The grinding wheel according to claim 1 or 2, wherein the processing area is rectangular, and the longitudinal direction of the processing area is inclined with respect to the tangent direction and the radial direction of a virtual arc extending in the circumferential direction that passes through the processing area.

4. The grinding wheel according to claim 3, wherein the longitudinal direction of the processing area is arranged to be inclined by an angle of inclination with respect to the tangential direction, and the angle of inclination is set to 15° to 60°.

5. The grinding wheel according to claim 3, wherein the plurality of processing parts are arranged in a row with spacing along the longitudinal direction, and the plurality of processing parts arranged in a row are arranged in multiple rows in the circumferential direction.

6. The grinding wheel according to claim 1 or 2, wherein the plurality of processing parts are arranged in a row with spacing in a direction inclined in the radial direction, the plurality of processing parts arranged in a row are arranged in multiple rows in the circumferential direction, the grinding wheel comprises connecting parts that connect the plurality of processing parts arranged in a row at the ends of the plurality of processing parts furthest from the processing surface and are integrally formed with the processing parts, the connecting parts and the plurality of processing parts connected by the connecting parts are configured as comb-shaped processing tips, and the grinding wheel comprises holding parts that are filled around the plurality of comb-shaped processing tips and hold the plurality of comb-shaped processing tips so that the processing area is exposed on the processing surface.

7. The grinding wheel according to claim 1 or 2, wherein the grinding wheel includes a holding portion that is filled around the plurality of processing portions so that the processing area is exposed on the processing surface, and the ratio of the area of ​​all the processing areas of the plurality of processing portions to the total area of ​​the processing surface is set to 5% to 20%.

8. The grinding wheel according to claim 1 or 2, wherein the grinding wheel includes a holding portion that is filled around the plurality of processing portions so that the processing area is exposed on the processing surface, and each of the plurality of processing portions is a rectangular plate shape that is long in the vertical direction perpendicular to the processing surface and short in the horizontal direction along the processing surface.

9. The grinding wheel according to claim 1 or 2, wherein each of the plurality of processing sections comprises a plurality of abrasive grains for polishing or grinding the workpiece, and a binder formed of a copper-free metal for holding the plurality of abrasive grains.

10. A method for polishing or grinding a workpiece made of silicon carbide using the grinding wheel described in claim 1 or 2.

11. The processing area is rectangular, and the longitudinal direction of the processing area is arranged to be inclined with respect to the tangent direction of a virtual arc extending in the circumferential direction passing through the processing area, and the radial direction, the plurality of processing parts are arranged in a row with spacing along the longitudinal direction, the plurality of processing parts arranged in a row are arranged in multiple rows in the circumferential direction, and are arranged so that they are in the direction of a first rotational direction in the circumferential direction as they move from the inside to the outside in the radial direction, the method includes the steps of: the control unit receiving an operation for the user to select either a first processing mode or a second processing mode; if the control unit receives an operation for selecting the first processing mode, the grinding wheel is rotated in the first rotational direction via a drive unit to rotate the grinding wheel and polishes or grinds the workpiece, and if the control unit receives an operation for selecting the second processing mode, the grinding wheel is rotated in a second rotational direction in the circumferential direction opposite to the first rotational direction via the drive unit and polishes or grinds the workpiece. The method according to claim 10.

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