Dressing ring and grinding method for workpiece

Abstract

To reduce a time required for work of replacing a workpiece and a dressing board when dressing is performed on a grinding wheel.SOLUTION: A dressing ring having a ring-shaped dressing member for dressing a processing stone is provided. Preferably, the dressing member has an opening in which a workpiece is arranged when the workpiece is ground. Also preferably, the dressing ring further includes a ring-shaped support plate having an upper surface on which the dressing member is fixed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a dressing ring having a ring-shaped dressing member for dressing a grinding wheel, a grinding process for grinding a workpiece, and a grinding method for a workpiece, which includes a dressing process for dressing the grinding wheel with the dressing member. [Background technology]

[0002] In the manufacturing process of semiconductor device chips, for example, first, a wafer is formed from a semiconductor such as silicon and has a plurality of planned dividing lines set in a grid pattern on its surface, and devices such as ICs (Integrated Circuits) are formed in each area partitioned by the plurality of planned dividing lines.

[0003] Next, the back side of the wafer is ground to thin the wafer, and then the wafer is divided along each of the planned division lines. As a result, the wafer is divided into multiple semiconductor device chips. A grinding machine is used to grind the wafer (workpiece) (see, for example, Patent Document 1).

[0004] The grinding device is equipped with a disk-shaped chuck table that holds the workpiece by suction. A grinding unit including a spindle is provided above the chuck table. A disk-shaped wheel mount is fixed to the lower end of the spindle, and an annular grinding wheel is attached to the underside of the wheel mount.

[0005] The grinding wheel has an annular wheel base, and a plurality of grinding stones are arranged at approximately equal intervals around the circumference of the wheel base on the underside of the wheel base. Each grinding stone has abrasive grains and a bond material for fixing the abrasive grains.

[0006] As the grinding wheel grinds the workpiece, the grinding ability of the underside of the grinding wheel decreases due to clogging, glazing, etc. Therefore, to restore the grinding ability, the grinding wheel needs to be dressed periodically.

[0007] However, in order to perform dressing, a first replacement operation is required, in which the workpiece that was being held by suction on the chuck table is moved from the chuck table to another location, and in its place, a circular dressing board is held by suction on the chuck table.

[0008] Furthermore, after dressing is completed, a second replacement operation is required in which the dressing board, which has been held by suction on the chuck table, is moved from the chuck table to another location, and the workpiece is then held by suction on the chuck table in its place.

[0009] The first and second replacement operations must be performed every time dressing is performed, and therefore the work efficiency is reduced by the time required for the replacement operations. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-124690 Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been made in consideration of the above problems, and aims to reduce the time required to replace the workpiece with the dressing board when dressing a grinding wheel. [Means for solving the problem]

[0015] According to another aspect of the present invention, there is provided a method for grinding a workpiece, comprising: a dressing member holding step of holding a ring-shaped dressing member for dressing a grinding stone of a grinding wheel on a holding surface of a chuck table capable of holding the workpiece; a workpiece holding step of holding the workpiece so that an upper surface of the workpiece is positioned higher than an upper surface of the dressing member at an opening of the dressing member held on the holding surface; a grinding step of grinding the workpiece with the grinding wheel rotating around a spindle; and a dressing step of rotating the chuck table around a predetermined rotation axis while positioning the grinding wheel above the dressing member and radially outward of the workpiece on the holding surface, thereby dressing the grinding stone with the dressing member.

[0016] Preferably, the grinding process includes creep feed grinding, in which the grinding wheel, the lower surface of which is positioned at a predetermined height position lower than the upper surface of the workpiece held on the holding surface and higher than the upper surface of the dressing member, rotates around the spindle, and the chuck table, which holds the workpiece and does not rotate around the predetermined rotation axis, are moved relatively along a predetermined direction perpendicular to the longitudinal direction of the spindle to grind the workpiece.

[0017] Also, preferably, the grinding step includes in-feed grinding, in which the workpiece is ground while the grinding wheel rotating around the spindle and the chuck table holding the workpiece and rotating around the predetermined rotation axis are moved relatively along the longitudinal direction of the spindle. [Effects of the Invention]

[0018] A dressing ring according to one aspect of the present invention includes a ring-shaped dressing member for dressing a grinding wheel. For example, by placing a workpiece in the opening of the dressing ring, the dressing ring and the workpiece can be simultaneously held by suction on the chuck table. This eliminates the time required to replace the workpiece and the dressing board on the chuck table.

[0019] A method for grinding a workpiece according to another aspect of the present invention includes a dressing member holding step for holding a ring-shaped dressing member on a holding surface of a chuck table, a workpiece holding step for holding the workpiece at an opening of the dressing member so that the upper surface of the workpiece is positioned higher than the upper surface of the dressing member, a grinding step, and a dressing step. In the grinding step, the workpiece can be ground with a grinding wheel rotating around a spindle.

[0020] Furthermore, in the dressing step, the grinding wheel is positioned above the dressing member and radially outward of the workpiece on the holding surface. In this state, the grinding wheel is moved relatively toward the holding surface while the chuck table is rotated about a predetermined rotation axis, thereby dressing the grinding stone with the dressing member.

[0021] In this way, the dressing ring and the workpiece can be held by suction on the chuck table at the same time, eliminating the time required to switch the workpiece and the dressing board on the chuck table. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1(A) is a perspective view of a dressing member and a support plate, and FIG. 1(B) is a perspective view of a dressing ring. [Figure 2] FIG. 1 is a flow chart showing a method for grinding one workpiece. [Figure 3]FIG. 3(A) is a view showing a dressing member holding step, and FIG. 3(B) is a perspective view of the dressing ring held by the holding surface. [Figure 4] FIG. 4(A) is a diagram showing a workpiece holding step, and FIG. 4(B) is a perspective view of the workpiece held on the holding surface. [Figure 5] FIG. 5(A) is a partially cross-sectional side view showing creep feed grinding, and FIG. 5(B) is a top view showing creep feed grinding. [Figure 6] FIG. 6(A) is a partially cross-sectional side view showing the dressing step, and FIG. 6(B) is a top view showing the dressing step. [Figure 7] FIG. 7(A) is a partially cross-sectional side view showing in-feed grinding, and FIG. 7(B) is a top view showing in-feed grinding. [Figure 8] FIG. 10 is a flowchart showing a grinding method for a plurality of workpieces according to a second embodiment. [Figure 9] FIG. 9(A) is a partially cross-sectional side view showing creep feed grinding, and FIG. 9(B) is a top view showing creep feed grinding. DETAILED DESCRIPTION OF THE INVENTION

[0023] An embodiment of the present invention will be described with reference to the accompanying drawings. First, the structure, shape, etc. of a dressing ring 2 used for dressing will be described. Fig. 1(A) is a perspective view of a dressing member 4 and a support plate 6 that constitute the dressing ring 2, and Fig. 1(B) is a perspective view of the dressing ring 2.

[0024] The dressing member 4 is used to dress processing stones such as the grinding stone 26b described below and a cutting blade (not shown) which is a stone used for cutting. The dressing member 4 has abrasive grains such as white alundum (WA) or green carbon (GC) and a bond material (binding material) for fixing the abrasive grains such as a vitrified bond or a resin bond.

[0025] The dressing member 4 of this embodiment is a flat ring-shaped member having an upper surface 4a and a lower surface 4b, and has an opening 4c of a predetermined diameter in the center, which is arranged approximately concentrically with the outer diameter of the dressing member 4. The dressing member 4 has a thickness of, for example, several hundred μm to 1 mm. The thickness of the dressing member 4 may be appropriately set depending on the thickness of the workpiece 11.

[0026] The lower surface 4b of the dressing member 4 is fixed with an adhesive (not shown) to the upper surface 6a of a flat ring-shaped support plate 6 having an upper surface 6a and a lower surface 6b. The support plate 6 is made of a resin such as an acrylic resin or a vinyl chloride resin, or a composite material such as glass fiber reinforced polyethylene phthalate.

[0027] The support plate 6 has a thickness of, for example, several hundred μm to 1 mm, but the thickness of the support plate 6 may be set appropriately depending on the thickness of the workpiece 11. The support plate 6 of this embodiment has an outer diameter larger than the outer diameter of the dressing member 4.

[0028] The support plate 6 has an opening 6c arranged approximately concentrically with the outer diameter. The opening 6c has approximately the same diameter as the opening 4c of the dressing member 4. The support plate 6 is arranged relative to the dressing member 4 so that the center of the opening 6c coincides with the center of the opening 4c when viewed from above.

[0029] Next, a method for grinding a workpiece 11 (see FIG. 4(A) etc.) will be described with reference to FIGS. 2 to 6. FIG. 2 is a flow diagram showing a grinding method when creep feed grinding is performed on one workpiece 11. A grinding device 8 is used to grind the workpiece 11.

[0030] Here, the configuration of the grinding device 8 will be described with reference to Figures 5(A) and 5(B). Note that the X-axis direction (front-back direction), Y-axis direction (left-right direction), and Z-axis direction (up-down direction) shown in Figures 5(A) and 5(B) are perpendicular to one another.

[0031] The grinding device 8 has a disk-shaped chuck table 10. The chuck table 10 has a frame 12 formed of non-porous ceramics or the like. The frame 12 has a cylindrical shape with a bottom and a diameter that is sufficiently larger than its height.

[0032] A plurality of flow paths are formed radially on the bottom surface of the cylindrical recess of the frame 12. A central flow path is also formed in the frame 12 so as to penetrate the center of the bottom surface of the recess. One end of the central flow path is connected to the plurality of flow paths formed radially, and the other end of the central flow path is connected to a suction source (not shown) such as a vacuum pump or an ejector.

[0033] A circular porous plate 14 made of porous ceramics is fixed in the recess of the frame 12. A non-porous ring 16 made of ceramics, like the frame 12, is provided on the outer periphery of the porous plate 14. Furthermore, a porous ring 18 made of porous ceramics, like the porous plate 14, is provided on the outer periphery of the non-porous ring 16.

[0034] The outer peripheral side of the porous ring 18 contacts the inner peripheral side of the frame 12. The upper surfaces of the frame 12, porous plate 14, non-porous ring 16, and porous ring 18 are flush with each other, forming a substantially flat holding surface 10a. Negative pressure is transmitted from a suction source to the upper surfaces of the porous plate 14 and porous ring 18.

[0035] In this embodiment, the diameter of the porous plate 14 is approximately the same as the diameter of the workpiece 11, and the outer diameter of the non-porous ring 16 (i.e., the inner diameter of the porous ring 18) is approximately the same as the inner diameter of the openings 4c and 6c.

[0036] A rotary drive source such as a motor is provided below the chuck table 10. The chuck table 10 can be rotated by the rotary drive source around a predetermined rotation axis (for example, a rotation axis disposed approximately parallel to the Z-axis direction).

[0037] The rotary drive source is supported by an X-axis direction moving plate (not shown) that constitutes an X-axis direction moving mechanism (not shown). The X-axis direction moving plate is slidably mounted on a pair of guide rails (not shown) that are arranged substantially parallel to the X-axis direction.

[0038] A nut portion (not shown) is provided on the underside of the X-axis direction moving plate. A ball screw (not shown) is rotatably connected to the nut portion. The ball screw is disposed between a pair of guide rails and is substantially parallel to the X-axis direction.

[0039] A drive source (not shown), such as a stepping motor, is connected to one end of the ball screw. When the drive source is operated, the X-axis direction moving plate moves along the X-axis direction. A grinding unit 20 is disposed above the chuck table 10.

[0040] A Z-axis direction moving mechanism (not shown) is connected to the grinding unit 20. The Z-axis direction moving mechanism has a pair of guide rails (not shown) arranged along the Z-axis direction. A Z-axis direction moving plate (not shown) is slidably attached to each guide rail.

[0041] A nut portion (not shown) is provided on the rear side of the Z-axis direction moving plate, and a ball screw (not shown) is rotatably connected to the nut portion, the ball screw being provided along the Z-axis direction between the pair of guide rails.

[0042] A drive source (not shown), such as a stepping motor, is connected to the upper end of the ball screw. When the drive source rotates the ball screw, the Z-axis direction moving plate moves in the Z-axis direction along the guide rail. The grinding unit 20 described above is fixed to the Z-axis direction moving plate.

[0043] The grinding unit 20 has a cylindrical spindle housing (not shown). A part of a columnar spindle 22 is rotatably accommodated in the spindle housing. In this embodiment, the spindle 22 is disposed such that its longitudinal direction is along the Z-axis direction.

[0044] A rotation drive source (not shown), such as a motor, is provided at the upper end of the spindle 22. An annular grinding wheel 26 is attached to the lower end of the spindle 22 via a disk-shaped wheel mount 24. The grinding wheel 26 has an annular wheel base 26a made of a metal material, such as an aluminum alloy.

[0045] A plurality of grinding wheels 26b are arranged at approximately equal intervals along the circumferential direction of the underside of the wheel base 26a on the underside of the wheel base 26a. The grinding wheels 26b have a binder made of, for example, metal, ceramics, resin, or the like, and abrasive grains made of diamond, cBN (cubic boron nitride), or the like.

[0046] When the spindle 22 is rotated, the grinding wheel 26 rotates around the spindle 22. When grinding the workpiece 11, grinding water such as pure water is supplied from a grinding water supply nozzle (not shown) to the contact area between the workpiece 11 and the grinding wheel 26b.

[0047] When grinding the workpiece 11 using the grinding device 8, first, the dressing ring 2 is placed on the holding surface 10a so that the dressing ring 2 overlaps the porous ring 18 and the upper surface 4a faces upward (see Figure 3(A)).

[0048] Next, the suction source is operated to suction-hold the dressing ring 2 with the porous ring 18 (i.e., part of the holding surface 10a) (dressing member holding step S10). Fig. 3(A) is a diagram showing the dressing member holding step S10, and Fig. 3(B) is a perspective view of the dressing ring 2 held with the holding surface 10a.

[0049] After the dressing member holding step S10, the workpiece 11 having approximately the same diameter as the outer periphery of the porous plate 14 is placed in the openings (i.e., openings 4c, 6c) of the dressing ring 2 (see FIG. 4(A)). The workpiece 11 is, for example, a disk-shaped silicon wafer having a plurality of devices (not shown) formed on its surface 11a.

[0050] However, there is no particular limitation on the material of the workpiece 11. The workpiece 11 may be made of a compound semiconductor such as silicon carbide (SiC) or gallium nitride (GaN), or may be made of other materials. A resin protective tape 13 is attached to the front surface 11a of the workpiece 11.

[0051] The workpiece 11 is held by suction on the front surface 11a side to the porous plate 14 (i.e., another part of the holding surface 10a) via the protective tape 13 so that the back surface 11b side is exposed upward (workpiece holding step S20). Fig. 4(A) is a diagram showing the workpiece holding step S20, and Fig. 4(B) is a perspective view of the workpiece 11 held by the holding surface 10a.

[0052] The total thickness of the workpiece 11 and the protective tape 13 before grinding is thicker than the thickness (i.e., the distance from the upper surface 4a to the lower surface 6b) of the dressing ring 2. Therefore, when the front surface 11a side is suction-held by the holding surface 10a, the back surface (upper surface) 11b of the workpiece 11 is located above the upper surface 4a of the dressing member 4.

[0053] The thickness of the dressing ring 2 is adjusted so that the upper surface 4a of the dressing member 4 is positioned below a height corresponding to the thickness of the workpiece 11 after grinding by the grinding device 8. The height position of the upper surface 4a may be adjusted by providing an annular step portion (not shown) on the outer periphery of the porous ring 18 and the frame body 12.

[0054] By providing an annular step portion, the upper surface 4a of the dressing member 4 can be positioned below a height corresponding to the thickness of the workpiece 11 after grinding, and by ensuring that the thickness of the dressing ring 2 is equal to or greater than a predetermined value, the mechanical strength of the dressing ring 2 can be ensured.

[0055] After the workpiece holding step S20, the workpiece 11 is ground (grinding step S30). In the grinding step S30 of this embodiment, creep feed grinding is performed on the workpiece 11. Fig. 5(A) is a partially cross-sectional side view showing creep feed grinding, and Fig. 5(B) is a top view showing creep feed grinding.

[0056] In creep feed grinding, the lower surface of the grinding stone 26b of the grinding wheel 26 rotating around the spindle 22 is positioned at a predetermined height position that is lower than the back surface 11b of the workpiece 11 held by suction on the holding surface 10a and higher than the upper surface 4a of the dressing member 4.

[0057] Furthermore, the chuck table 10 holding the workpiece 11 is moved along the X-axis direction (predetermined direction) from a predetermined movement start position without rotating around the rotation axis 10b (see FIG. 6(A)).

[0058] When the workpiece 11 moves directly below the grinding wheel 26b, the back surface 11b of the workpiece 11 comes into contact with the lower surface of the grinding wheel 26b, and the back surface 11b is ground. In this manner, the back surface 11b of the workpiece 11 is ground while the chuck table 10 and the grinding wheel 26 are moved relatively in the X-axis direction.

[0059] The chuck table 10 is fed in the X-axis direction to move the workpiece 11 inside the circularly arranged grinding wheels 26b, and then the grinding unit 20 is temporarily raised so that the lower surfaces of the grinding wheels 26b are positioned above the back surface 11b. Then, the chuck table 10 is returned to the movement start position.

[0060] One grinding (one pass) performed by moving the chuck table 10 from its starting position, the lifting of the grinding unit 20, and the return of the chuck table 10 to its starting position constitute a series of operations when performing one creep feed grinding on one workpiece 11.

[0061] For example, 10 passes (i.e., 10 sets of operations) are required to thin the workpiece 11 to a predetermined thickness. However, the grinding ability of the grinding wheel 26b usually decreases before the completion of the 10 passes, so it is necessary to apply dressing to the grinding wheel 26b.

[0062] For example, at the end of the fifth pass, dressing is required (YES in S40) (see FIG. 2). In this case, the grinding wheel 26b is dressed with the dressing ring 2 (dressing step S50). FIG. 6(A) is a partially cross-sectional side view showing the dressing step S50, and FIG. 6(B) is a top view showing the dressing step S50.

[0063] In the dressing process S50, the grinding wheel 26 is positioned above the dressing member 4 and radially outside the outer periphery of the workpiece 11 on the holding surface 10a, and the grinding wheel 26 is moved relatively toward the holding surface 10a while the chuck table 10 is rotated around the rotation axis 10b.

[0064] For example, the rotation speed of the chuck table 10 is set to a predetermined value of 40 rpm or more and 300 rpm, and the rotation speed of the spindle 22 is set to a predetermined value of 1000 rpm or more and 3000 rpm. Also, for example, the grinding feed speed of the grinding wheel 26 (i.e., the moving speed of the grinding wheel 26 downward along the Z-axis direction) is set to a predetermined value of 0.5 μm / s or more and 6.0 μm / s or less.

[0065] The grinding ability of the grinding wheel 26b is substantially restored by dressing the grinding wheel 26b for a predetermined time after the lower surface of the grinding wheel 26b comes into contact with the upper surface 4a of the dressing member 4. For example, when dressing the grinding wheel 26b for finish grinding on a grinding wheel with a diameter of 200 mm, the dressing conditions are set as follows:

[0066] Chuck table rotation speed: 40 rpm Spindle speed: 2000 rpm Grinding feed rate 1.0μm / s Predetermined time 300s

[0067] After the dressing step S50, grinding of one workpiece 11 has not yet been completed (NO in S60), so the process returns to the grinding step S30, and creep feed grinding corresponding to the remaining 6th to 10th passes is performed. On the other hand, if creep feed grinding corresponding to the 10th pass has been completed (YES in S60), the flow ends.

[0068] In this embodiment, the workpiece 11 and the dressing ring 2 can be simultaneously held by suction on the holding surface 10a, thereby eliminating the time required to swap the workpiece 11 and the dressing board on the chuck table 10.

[0069] Additionally, in the dressing step S50, the grinding wheel 26 is dressed in the manner of in-feed grinding (i.e., in-feed dressing). Compared to creep feed dressing, which dresses the grinding wheel 26 in the manner of creep feed grinding, in-feed dressing has the advantage of being able to make the lower end positions of the abrasive grains more uniform on the lower surface of the grinding stone 26b.

[0070] Next, a second embodiment will be described. In the grinding step S30 of the second embodiment, in-feed grinding is performed instead of creep feed grinding. Fig. 7(A) is a partially cross-sectional side view showing in-feed grinding, and Fig. 7(B) is a top view showing in-feed grinding.

[0071] The shape of the holding surface 10a in the second embodiment is different from that in the first embodiment, and has a conical shape with the center slightly protruding compared to the outer periphery. However, for convenience, the holding surface 10a is shown as substantially flat in Figure 7(A).

[0072] Furthermore, the rotation axis 10b is tilted with respect to the Z axis so that a portion of the holding surface 10a is approximately parallel to the grinding surface defined by the trajectory of the lower surface of the grinding wheel 26b, but in Figure 7(A) for convenience, the rotation axis 10b is shown as being approximately parallel to the Z axis direction.

[0073] In in-feed grinding, the grinding wheel 26 rotating around the spindle 22 is fed along the Z-axis direction toward the chuck table 10 rotating around the rotation axis 10b while holding the workpiece 11.

[0074] When the grinding wheel 26b comes into contact with the back surface 11b of the workpiece 11, the back surface 11b is ground. In this manner, the workpiece 11 is ground while the grinding wheel 26 and the chuck table 10 are moved relatively along the Z-axis direction.

[0075] 8 is a flow diagram showing a method for grinding a plurality of workpieces 11 according to the second embodiment. In the grinding step S30, after one workpiece 11 has been thinned to a predetermined thickness, if dressing is not required (NO in S40), the workpiece 11 is removed from the holding surface 10a, and another workpiece 11 is newly loaded onto the chuck table 10.

[0076] In this manner, the workpieces 11 are sequentially in-feed ground. However, after one or more workpieces 11 have been in-feed ground, it is necessary to perform dressing on the grinding wheel 26b depending on the degree of deterioration in the grinding ability of the grinding wheel 26b (YES in S40).

[0077] In the second embodiment, in-feed dressing is performed in the dressing step S50 as in the first embodiment, so the workpiece 11 may remain suction-held on the holding surface 10a during processing. After processing, the workpiece 11 may be carried out from the holding surface 10a.

[0078] After the dressing step S50, if another workpiece 11 is to be ground (YES in S62), the process returns to the workpiece holding step S20. On the other hand, if another workpiece 11 is not to be ground (NO in S62), the flow ends.

[0079] In the second embodiment, the workpiece 11 and the dressing ring 2 can be simultaneously held by suction on the holding surface 10a, eliminating the time required to swap the workpiece 11 and the dressing board on the chuck table 10.

[0080] Next, a third embodiment will be described. In the third embodiment, creep feed grinding is performed on three strip substrates 21, instead of one disk-shaped workpiece 11, as shown in Figures 9(A) and 9(B).

[0081] Each strip substrate 21 has a rectangular plate shape, and a plurality of device chips (not shown) are provided inside it so as to be covered with sealing resin, molding resin, etc. Each strip substrate 21 is held by suction on the holding surface 10a.

[0082] However, the structure of the chuck table 10 is different from that of the first and second embodiments. Specifically, the porous plate 14 has rectangular suction areas 14a on its upper surface, which correspond to the respective strip substrates 21. Each suction area 14a is surrounded by one or two linear boundary portions 30, each formed of non-porous ceramic, and a non-porous ring 16.

[0083] In addition, the holding surface 10a in the third embodiment is approximately flat, as in the first embodiment, and the upper surfaces of the frame body 12, porous plate 14, non-porous ring 16, porous ring 18 and boundary portion 30 are flush.

[0084] In the third embodiment, the upper surface 21a of the strip substrate 21 is ground according to the flow shown in Fig. 2. In the grinding step S30, three strip substrates 21 are simultaneously held by suction on the chuck table 10, and the chuck table 10 is moved in the X-axis direction without rotating around the rotation axis 10b, thereby creep feed grinding each strip substrate 21.

[0085] 9(A) is a partially cross-sectional side view showing creep feed grinding, and FIG. 9(B) is a top view showing creep feed grinding. In this embodiment, the workpiece 11 and the dressing ring 2 can be simultaneously held by suction on the holding surface 10a, eliminating the time required to replace the workpiece 11 and the dressing board on the chuck table 10.

[0086] In addition, the structures, methods, etc. according to the above-described embodiments can be modified as appropriate without departing from the scope of the object of the present invention. [Explanation of symbols]

[0087] 2: Dressing ring 4: Dressing member, 4a: Upper surface, 4b: Lower surface, 4c: Opening 6: Support plate, 6a: Upper surface, 6b: Lower surface, 6c: Opening 8: grinding device, 10: chuck table, 10a: holding surface, 10b: rotating shaft 11: Workpiece, 11a: Front surface, 11b: Back surface (top surface), 13: Protective tape 12: Frame body, 14: Porous plate, 14a: Suction area 16: Non-porous ring, 18: Porous ring 20: Grinding unit, 22: Spindle, 24: Wheel mount 21: strip substrate, 21a: upper surface 26: grinding wheel, 26a: wheel base, 26b: grinding stone, 30: boundary portion

Claims

1. A method for grinding a workpiece, comprising: a dressing member holding step of holding a ring-shaped dressing member for dressing a grinding stone of the grinding wheel on a holding surface of a chuck table capable of holding the workpiece; a workpiece holding step of holding the workpiece so that an upper surface of the workpiece is positioned higher than an upper surface of the dressing member at an opening of the dressing member held by the holding surface; a grinding step of grinding the workpiece with the grinding wheel rotating around a spindle; a dressing step of dressing the grinding wheel with the dressing member by positioning the grinding wheel above the dressing member and radially outward of the holding surface from the workpiece, and rotating the chuck table around a predetermined rotation axis while moving the grinding wheel relatively toward the holding surface.

2. 2. The method for grinding a workpiece according to claim 1, wherein the grinding step includes creep feed grinding, in which the grinding wheel, the lower surface of which is positioned at a predetermined height position lower than the upper surface of the workpiece held on the holding surface and higher than the upper surface of the dressing member and which rotates around the spindle, and the chuck table, which holds the workpiece and does not rotate around the predetermined rotation axis, are moved relatively along a predetermined direction perpendicular to the longitudinal direction of the spindle to grind the workpiece.

3. 2. The method for grinding a workpiece according to claim 1, wherein the grinding step includes in-feed grinding, in which the workpiece is ground while the grinding wheel rotating around the spindle and the chuck table holding the workpiece and rotating around the predetermined rotation axis are moved relatively along the longitudinal direction of the spindle.

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