Wafer processing method

Abstract

To inhibit occurrence of chipping when a protruding part of a TAIKO wafer is removed.SOLUTION: In order to cut and remove a protruding part 210 from a recessed part 200 of a wafer 100, a cutting blade is cut into a cut-in position C1 set on the basis of a notch 110 indicating the crystal orientation of the wafer 100 to form a cutting groove. The cut-in position is, for example, a position offset from the notch 110 in the circumferential direction of the wafer 100 by zero degrees or 180 degrees. Since the cutting blade is cut into the wafer 100, matching with the crystal orientation of the wafer 100, large chipping can be inhibited from occurring in the cutting groove. Thus, cracks of the recessed part can be inhibited.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for processing a wafer.

Background Art

[0002] As disclosed in Patent Documents 1 and 2, after forming a metal film on the surface of a TAIKO wafer whose central portion has been ground, the ring-shaped convex portion that serves as a reinforcing portion of the outer peripheral portion is removed, and then it is divided into chips.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0004] In removing the convex portion, as disclosed in Patent Document 3, a cutting groove is formed by cutting the wafer in a ring shape with a cutting blade. At this time, large chipping may occur on the side portion of the cutting groove. Therefore, as in Patent Documents 4 and 5, when removing the convex portion, starting from the chipping, the wafer from which the convex portion has been removed and the convex portion may crack.

[0005] Therefore, an object of the present invention is to suppress the occurrence of chipping when removing the convex portion of the TAIKO wafer.

Means for Solving the Problems

[0006] The first wafer processing method of the present invention includes forming a ring-shaped cutting groove with a cutting blade at the boundary between a concave portion and a convex portion of a wafer having a concave portion with a circular bottom surface formed by grinding a central portion into a circular shape and a ring-shaped convex portion disposed outside the concave portion, and is a wafer processing method including: a holding step of holding the bottom surface of the concave portion of the wafer on the holding surface of a chuck table via a sheet; after the holding step, detecting a mark indicating the crystal orientation of the wafer, and positioning the cutting position of the cutting blade at the boundary between the concave portion and the convex portion set based on the mark directly below the cutting blade; a positioning step; after the positioning step, relatively moving the cutting blade and the chuck table in a direction approaching each other to cut the cutting blade into the cutting position to a depth penetrating the concave portion; a cutting step; after the cutting step, rotating the chuck table to form a ring-shaped cutting groove penetrating the concave portion at the boundary between the concave portion and the convex portion with the cutting blade; a cutting groove forming step.

[0007] The method for processing a second wafer according to the present invention includes forming a ring-shaped cutting groove with a cutting blade at the boundary between a concave portion and a convex portion of a wafer having a concave portion with a circular bottom surface formed by grinding a central portion into a circular shape and a ring-shaped convex portion disposed outside the concave portion. The method for processing a wafer includes a holding step of holding the bottom surface of the concave portion of the wafer on the holding surface of a chuck table via a sheet, a positioning step of detecting a mark indicating the crystal orientation of the wafer after the holding step and positioning the cutting position of the cutting blade at the boundary between the concave portion and the convex portion set based on the mark directly below the cutting blade, a cutting step of moving the cutting blade and the chuck table relatively in a direction approaching each other after the positioning step to cut the cutting blade into the cutting position to a depth that does not penetrate the concave portion, and a cutting groove forming step of rotating the chuck table and moving the cutting blade and the chuck table relatively in a direction approaching each other after the cutting step to form a ring-shaped cutting groove that penetrates the concave portion at the boundary between the concave portion and the convex portion with the cutting blade.

[0008] In the methods for processing the first and second wafers, in the positioning step, the cutting position of the cutting blade may be set to a position shifted by 0 degrees or 180 degrees in the circumferential direction of the wafer from the mark.

Advantages of the Invention

[0009] In the processing method of the present invention, in order to cut and remove the convex portion from the wafer, the cutting blade is cut into the cutting position set based on the mark indicating the crystal orientation of the wafer, and the chuck table is rotated to form a cutting groove. This cutting position is, for example, a position shifted by 0 degrees or 180 degrees in the circumferential direction of the wafer from the mark.

[0010] Thus, in the processing method of the present invention, since the cutting blade is cut into the wafer in accordance with the crystal orientation of the wafer, it is possible to suppress the occurrence of large chipping in the cutting groove. Thereby, it becomes possible to suppress cracking of the concave portion. In addition, since large chipping is less likely to occur in the convex portion, when removing the convex portion, it is possible to quickly remove the convex portion in a ring shape. Therefore, productivity can be improved.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0012] The wafer 100 shown in FIGS. 1(a) and (b) is an example of a workpiece and has a substantially disc shape. The wafer 100 is formed of a semiconductor material such as silicon, for example.

[0013] As shown in FIG. 1(a), on the surface 101 which is one side of the wafer 100, a grid-like planned division line 112 is formed. Various devices 111 are formed in each region partitioned by the planned division line 112. Also, on the outer peripheral portion of the wafer 100, a notch 110 is formed as a mark indicating the crystal orientation of the wafer 100.

[0014] Further, on the wafer 100, so-called TAIKO grinding is performed to grind the central portion of the back surface 102, which is the other side, into a circular shape. As a result, as shown in FIG. 1(b), the wafer 100 has a concave portion 200 having a circular bottom surface 202 and an inner side surface 201 on the back surface 102, and a ring-shaped convex portion 210 disposed outside the concave portion 200.

[0015] Also, as shown in FIGS. 1(a), 2(a), and 2(b), a dicing tape 103, which is an example of a sheet, is adhered to the back surface 102 of the wafer 100. A ring frame 105 is adhered to the outer periphery of the dicing tape 103. In this way, the wafer 100 is processed in a cutting device 1 (see FIG. 3) in a state of a workpiece set 107 supported by the ring frame 105 via the dicing tape 103. Note that in FIG. 2(a), the boundary portion 220 between the concave portion 200 and the convex portion 210 in the wafer 100 is shown by a dashed line.

[0016] The cutting device 1 shown in FIG. 3 is an example of a processing device for processing the wafer 100. The cutting device 1 performs cutting processing on the wafer 100. The cutting device 1 includes a base 10, a portal column 14 erected on the base 10, and a control unit 7 for controlling each member of the cutting device 1.

[0017] On the base 10, an X-axis direction moving mechanism 30 is disposed. The X-axis direction moving mechanism 30 is an example of a moving unit that relatively approaches and separates the cutting blade 181 of the cutting unit 18, which is a processing unit, and the chuck table 20. In the present embodiment, the X-axis direction moving mechanism 30 moves the chuck table 20 along the cutting feed direction (X-axis direction).

[0018] The X-axis direction moving mechanism 30 includes a pair of guide rails 31 extending in the X-axis direction, an X-axis table 33 placed on the guide rails 31, a ball screw 32 extending parallel to the guide rails 31, and a motor 34 that rotates the ball screw 32.

[0019] The pair of guide rails 31 are arranged on the upper surface of the base 10 in parallel with the X-axis direction. The X-axis table 33 is installed on the pair of guide rails 31 so as to be slidable along these guide rails 31. On the X-axis table 33, a θ table 25 and a chuck table 20 are arranged.

[0020] The ball screw 32 is screwed into a nut portion (not shown) provided on the X-axis table 33. The motor 34 is connected to one end of the ball screw 32 and rotationally drives the ball screw 32. When the ball screw 32 is rotationally driven, the X-axis table 33, the θ table 25, and the chuck table 20 move along the X-axis direction along the guide rails 31.

[0021] In the present embodiment, the X-axis direction moving mechanism 30 is configured to move the chuck table 20 between a forward (+X direction side) holding position for holding the workpiece set 107 on the holding surface 22 of the chuck table 20 and a rearward (-X direction side) processing position where the wafer 100 is cut.

[0022] The chuck table 20 holds the wafer 100, which is the workpiece. In the present embodiment, the wafer 100 is held by the chuck table 20 in the state of the workpiece set 107 described above. As shown in FIG. 4, the chuck table 20 includes a table portion 21 formed in a disk shape, a ring support portion 26 disposed around the table portion 21, a lifting mechanism 261 for adjusting the height of the ring support portion 26, and four clamps 28.

[0023] The table portion 21 has a substantially disk-shaped frame body 23, and a holding member 24 made of a porous member such as porous ceramics is provided in a recess provided on the upper surface of the frame body 23. The upper surface of the holding member 24 serves as a holding surface 22 that sucks and holds the wafer 100 via the dicing tape 103.

[0024] Also, the holding member 24 is connected to a suction source 401. In the chuck table 20, when the holding member 24 is communicated with the suction source 401, the recess 200 (circular bottom surface 202) on the back surface 102 of the wafer 100 is sucked and held via the dicing tape 103 by the holding surface 22.

[0025] At this time, the convex portion 210 on the back surface 102 of the wafer 100 is supported by the ring support portion 26 via the dicing tape 103. At this time, the height of the upper surface of the ring support portion 26 is arranged below the holding surface 22 in accordance with the lower surface of the convex portion 210, which is at a position lower than the circular bottom surface 202 of the recess 200.

[0026] Furthermore, the ring frame 105 of the workpiece set 107 is clamped and fixed from four directions by the clamps 28. In this way, the chuck table 20 holds the workpiece set 107.

[0027] Further, as shown in FIG. 3, the chuck table 20 is supported by a θ table 25 disposed on the bottom surface side of the chuck table 20. The θ table 25 is provided rotatably within the XY plane on the upper surface of the X-axis table 33. Further, the θ table 25 has a table motor 251 for rotating the θ table 25 and the table unit 21. Therefore, the θ table 25 supports the chuck table 20 and can rotationally drive the chuck table 20 within the XY plane.

[0028] On the rear side (-X direction side) of the base 10, a gantry column 14 is erected so as to straddle the X-axis direction movement mechanism 30.

[0029] On the front surface (+X direction side surface) of the gantry column 14, a cutting unit movement mechanism 13 for moving the cutting unit 18 is provided. The cutting unit movement mechanism 13 indexes the cutting unit 18 in the Y-axis direction and feeds it in the Z-axis direction.

[0030] The cutting unit movement mechanism 13 includes a Z-axis direction movement mechanism 16 for moving the cutting unit 18 in the Z-axis direction and a Y-axis direction movement mechanism 17 for moving the cutting unit 18 in the Y-axis direction.

[0031] The Y-axis direction movement mechanism 17 is an example of a movement unit that relatively approaches and separates the cutting blade 181 of the cutting unit 18, which is a processing unit, and the chuck table 20 along the Y-axis direction. In the present embodiment, the Y-axis direction movement mechanism 17 is configured to reciprocate the cutting blade 181 of the cutting unit 18 with respect to the chuck table 20. The Y-axis direction movement mechanism 17 is disposed on the front surface of the gantry column 14. The Y-axis direction movement mechanism 17 reciprocates the Z-axis direction movement mechanism 16 that supports the cutting unit 18 along the Y-axis direction.

[0032] The Y-axis direction movement mechanism 17 includes a pair of guide rails 171 extending in the Y-axis direction, a Y-axis table 173 attached to the guide rails 171, a ball screw 170 extending parallel to the guide rails 171, and a motor 172 for rotating the ball screw 170.

[0033] The pair of guide rails 171 are arranged on the front surface of the portal column 14 in parallel in the Y-axis direction. The Y-axis table 173 is installed slidably along these guide rails 171 on the pair of guide rails 171. The Z-axis direction movement mechanism 16 and the cutting unit 18 are attached to the Y-axis table 173.

[0034] The ball screw 170 is screwed into a nut portion (not shown) provided on the Y-axis table 173. The motor 172 is connected to one end of the ball screw 170 and rotationally drives the ball screw 170. When the ball screw 170 is rotationally driven, the Y-axis table 173, the Z-axis direction movement mechanism 16, and the cutting unit 18 move in the Y-axis direction along the guide rails 171.

[0035] The Z-axis direction movement mechanism 16 is an example of a movement unit that relatively approaches and separates the cutting blade 181 of the cutting unit 18, which is a processing unit, and the chuck table 20 along the Z-axis direction. In the present embodiment, the Z-axis direction movement mechanism 16 is configured to reciprocate the cutting unit 18 along the Z-axis direction with respect to the chuck table 20.

[0036] The Z-axis direction movement mechanism 16 includes a pair of guide rails 161 extending in the Z-axis direction, a support member 163 arranged on the guide rails 161, a ball screw 160 extending parallel to the guide rails 161, and a motor 162 for rotating the ball screw 160.

[0037] A pair of guide rails 161 are arranged on the Y-axis table 173 in parallel with the Z-axis direction. The support member 163 is installed on the pair of guide rails 161 so as to be slidable along these guide rails 161. A cutting unit 18 is attached to the lower end of the support member 163.

[0038] The ball screw 160 is screwed into a nut portion (not shown) provided on the support member 163. The motor 162 is connected to one end of the ball screw 160 and rotationally drives the ball screw 160. When the ball screw 160 is rotationally driven, the support member 163 and the cutting unit 18 move in the Z-axis direction along the guide rail 161.

[0039] The cutting unit 18 is an example of a processing unit that processes the wafer 100 held on the chuck table 20. The cutting unit 18 has a cutting blade 181 and an imaging unit (camera) 182. The imaging unit 182 images the wafer 100 held on the holding surface 22 of the chuck table 20 and detects the cutting portion of the wafer 100. The cutting blade 181 is a cutting tool for cutting the wafer 100 and is configured to be rotationally driven by a rotation mechanism (not shown).

[0040] The control unit 7 includes a CPU that performs arithmetic processing according to a control program, and a storage medium such as a memory. The control unit 7 executes various processes and controls each component of the cutting device 1.

[0041] Hereinafter, a method for processing a wafer controlled by the control unit 7 will be described. The method for processing a wafer according to the present embodiment is a method of forming a ring-shaped cutting groove with a cutting blade 181 at the boundary between the concave portion 200 and the convex portion 210 in order to remove the convex portion 210 from the wafer 100 (concave portion 200).

[0042] 〔Holding step〕 In this step, the circular bottom surface 202 of the recess 200 of the wafer 100 is held on the holding surface 22 of the chuck table 20 via the dicing tape 103. In this step, for example, the loading device 8 shown in FIG. 4 is used.

[0043] The loading device 8 is provided in the cutting device 1 and has a transfer pad 80 that holds the workpiece set 107, a transfer arm 81 that supports the transfer pad 80, and a moving mechanism 810 that supports and moves the transfer pad 80 and the transfer arm 81.

[0044] The transfer arm 81 is provided with the transfer pad 80 at its tip. Also, the base end side of the transfer arm 81 is connected to the moving mechanism 810. The moving mechanism 810 is configured to move the transfer pad 80 along the Z-axis direction (vertical direction) and the XY direction (horizontal direction) together with the transfer arm 81.

[0045] The transfer pad 80 has a support plate portion 83. The support plate portion 83 is supported at the tip of the transfer arm 81 via a plate shaft portion 82. Also, the transfer pad 80 is provided with a plurality (for example, four) of frame holding portions 85 (only two are shown in FIG. 4) that suck and hold the upper surface of the ring frame 105 of the workpiece set 107 on the support plate portion 83.

[0046] Then, in the holding step, the control unit 7 arranges the chuck table 20 at the holding position on the +X direction side by the X-axis direction moving mechanism 30 shown in FIG. 1. Next, the control unit 7 takes out one workpiece set 107 from, for example, a cassette (not shown) and holds it by the loading device 8 as shown in FIG. 4.

[0047] Thereafter, the control unit 7 controls the loading device 8 to place the circular bottom surface 202 of the concave portion 200 of the wafer 100 on the holding surface 22 of the chuck table 20 and suck and hold it by the holding surface 22, and place the convex portion 210 on the ring support portion 26. Further, the clamp 28 clamps and fixes the ring frame 105 of the workpiece set 107. Thereby, as shown in FIG. 5, the workpiece set 107 is held by the chuck table 20.

[0048] 〔Positioning step〕 After the holding step, the positioning step is performed. In this step, the control unit 7 detects the notch 110 which is an example of the mark indicating the crystal orientation of the wafer 100, and positions the cutting position of the cutting blade 181 (the position where the cutting blade 181 is inserted) at the boundary between the concave portion 200 and the convex portion 210 set based on the notch 110 directly below the cutting blade 181.

[0049] That is, the control unit 7 first controls the X-axis direction movement mechanism 30 (see FIG. 1) to place the chuck table 20 at the rear (-X direction side) processing position. At this position, as shown in FIG. 5, the cutting blade 181 of the cutting unit 18 is disposed above the wafer 100 of the workpiece set 107 held by the chuck table 20.

[0050] Furthermore, the loading device 8 controls the X-axis direction movement mechanism 30 and the Y-axis direction movement mechanism 17 (see FIG. 1) to adjust the positions of the cutting unit 18 and the chuck table 20 so that the cutting blade 181 of the cutting unit 18 is disposed on the boundary portion 220 between the concave portion 200 and the convex portion 210 of the wafer 100 and the imaging unit 182 of the cutting unit 18 is disposed on the outer peripheral portion of the wafer 100.

[0051] Next, the control unit 7 controls the θ table 25 to rotate the chuck table 20 as shown by the arrow 301 in FIG. 5, and images the outer peripheral portion of the wafer 100 using the imaging unit 182 to detect the notch 110 of the wafer 100.

[0052] After that, based on the detected position of the notch 110, the control unit 7 rotates the chuck table 20 by the θ table 25 to position the preset cutting position of the cutting blade 181 at the boundary portion 220 of the wafer 100 directly below the cutting blade 181. In the present embodiment, the cutting position of the cutting blade 181 is set based on the notch 110 indicating the crystal orientation of the wafer 100 at the boundary portion 220 between the concave portion 200 and the convex portion 210. For example, as shown in FIGS. 1(a) and 2(a), the cutting position C1 is set at a position on the boundary portion 220 that is shifted 0 degrees or 180 degrees in the circumferential direction of the wafer 100 from the notch 110.

[0053] 〔Cutting-in step〕 After the positioning step, the cutting-in step is performed. In this step, the control unit 7 relatively moves the cutting blade 181 and the chuck table 20 in a direction approaching each other, and cuts the cutting blade 181 into the boundary portion 220 at the above-described cutting position to a depth that penetrates the concave portion 200 of the wafer 100.

[0054] That is, the control unit 7 rotates the cutting blade 181 as shown by the arrow 302 in FIG. 6, and lowers the cutting blade 181 disposed directly above the cutting position at the boundary portion 220 of the wafer 100 along the Z-axis direction (vertical direction) as shown by the arrow 303 in FIG. 6 by the Z-axis direction moving mechanism 16 (see FIG. 1). Then, as shown in FIG. 6, the control unit 7 lowers the cutting blade 181 to a depth that penetrates the concave portion 200 at the cutting position at the boundary portion 220 of the wafer 100. As a result, the tip of the cutting blade 181 reaches the dicing tape 103 of the work set 107.

[0055] 〔Cutting groove forming step〕 After the notching step, a cutting groove forming step is performed. In this step, the control unit 7 rotates the chuck table 20, and the cutting blade 181 forms a ring-shaped cutting groove that penetrates the recess 200 at the boundary portion 220, which is the boundary between the recess 200 and the protrusion 210.

[0056] That is, the control unit 7 controls the θ table 25 to rotate the chuck table 20 as indicated by the arrow 301 in FIG. 7 while the rotating cutting blade 181 is cutting into the boundary portion 220 of the wafer 100. As a result, the entire boundary portion 220 of the wafer 100 is cut by the cutting blade 181 rotating at a depth that penetrates the recess 200 of the wafer 100. Thereby, as shown in FIG. 7, a ring-shaped cutting groove 230 that penetrates the recess 200 is formed in the boundary portion 220 of the wafer 100. As a result, the ring-shaped protrusion 210 is cut off from the recess 200 of the wafer 100.

[0057] 〔Protrusion removal step〕 After the cutting groove forming step, a protrusion removal step is performed. In this step, the control unit 7 removes the ring-shaped protrusion 210 cut from the recess 200 from the wafer 100. For this purpose, in the present embodiment, the carry-out device 9 shown in FIG. 8 is used.

[0058] The carry-out device 9 is provided in the cutting device 1 and has a transfer pad 90 that holds the cut ring-shaped protrusion 210, a transfer arm 91 that supports the transfer pad 90, and a moving mechanism 910 that supports and moves the transfer pad 90 and the transfer arm 91.

[0059] The transfer arm 91 is provided with a transfer pad 90 at its tip. Also, the base end side of the transfer arm 91 is connected to the moving mechanism 910. The moving mechanism 910 is configured to move the transfer pad 90 along the Z-axis direction (vertical direction) and the XY direction (horizontal direction) together with the transfer arm 91.

[0060] The transfer pad 90 has a support plate portion 93. The support plate portion 93 is supported at the tip of the transfer arm 91 via a plate shaft portion 92. Further, the transfer pad 90 includes a plurality (for example, four) of convex portion holding portions 95 that hold the ring-shaped convex portion 210 on the support plate portion 93 (only two are shown in FIG. 8). The convex portion holding portion 95 is provided on the lower surface of the support plate portion 93 and is configured to be movable in a direction parallel to this surface.

[0061] Then, in the convex portion removing step, the control unit 7 arranges the chuck table 20 at the holding position on the +X direction side by the X-axis direction moving mechanism 30 shown in FIG. 1. Next, as shown in FIG. 8, the control unit 7 arranges the carry-out device 9 above the chuck table 20. Further, the control unit 7 lowers the transfer pad 90 by the moving mechanism 910 and holds the ring-shaped convex portion 210 so as to sandwich it from the outside by the convex portion holding portion 95 as shown by the arrow 304.

[0062] After that, the control unit 7 removes the convex portion 210 from the concave portion 200 of the wafer 100 by raising the transfer pad 90. After that, the control unit 7 transports the removed convex portion 210 to a predetermined recovery device by the carry-out device 9, for example. Further, as shown by the arrow 305 in FIG. 8, the control unit 7 raises the ring support portion 26 using the elevating mechanism 261 so that its upper surface is flush with the holding surface 22.

[0063] 〔Chip formation step〕 After the convex portion removing step, if necessary, a chip formation step is performed. In this step, the control unit 7 cuts the wafer 100 (concave portion 200) along the division planned line 112 by the cutting blade 181 of the cutting unit 18. Thus, a plurality of chips including devices are formed. Note that this chip formation step may not be performed.

[0064] As described above, in the present embodiment, in order to cut and remove the convex portion 210 from the wafer 100, the cutting blade 181 is inserted at the cutting position set based on the notch 110 indicating the crystal orientation of the wafer 100, and the chuck table 20 is rotated to form the cutting groove 230. This cutting position is, for example, a position shifted by zero degrees or 180 degrees in the circumferential direction of the wafer 100 from the notch 110.

[0065] As described above, in the present embodiment, the cutting blade 181 is inserted into the wafer 100 in accordance with the crystal orientation of the wafer 100 (for example, perpendicular to the crystal orientation). Therefore, it is possible to suppress the occurrence of large chipping in the cutting groove 230. As a result, it is possible to suppress cracking of the concave portion 200. In addition, since large chipping is less likely to occur in the convex portion 210, when removing the convex portion 210, the convex portion 210 can be quickly removed in a ring shape. Therefore, productivity can be improved.

[0066] In the present embodiment, in the cutting step after the positioning step, the cutting blade 181 is inserted to a depth that penetrates the concave portion 200 of the wafer 100 at the above-described cutting position in the boundary portion 220 of the wafer 100. In this regard, the control unit 7 may move the cutting blade 181 and the chuck table 20 relatively in a direction approaching each other in the cutting step, so that the cutting blade 181 is inserted to a depth that does not penetrate the concave portion 200 of the wafer 100 at the cutting position.

[0067] In this case, as shown in FIG. 9, the control unit 7 rotates the cutting blade 181 as indicated by the arrow 302, and causes the cutting blade 181 disposed directly above the cutting position at the boundary portion 220 of the wafer 100 to descend along the Z-axis direction as indicated by the arrow 303 by the Z-axis direction moving mechanism 16 (see FIG. 1). Then, as shown in FIG. 9, the control unit 7 descends the cutting blade 181 to a depth that does not penetrate the concave portion 200 at the cutting position in the boundary portion 220 of the wafer 100. As a result, the tip of the cutting blade 181 remains within the wafer 100 (concave portion 200).

[0068] In this case, in the cutting groove forming step after the cutting step, the control unit 7 rotates the chuck table 20 and relatively moves the cutting blade 181 and the chuck table 20 in a direction approaching each other, so that the cutting blade 181 forms a ring-shaped cutting groove 230 that penetrates the concave portion 200 at the boundary portion 220 that is the boundary between the concave portion 200 and the convex portion 210.

[0069] That is, the control unit 7 controls the θ table 25 to rotate the chuck table 20 while the rotating cutting blade 181 is cutting into the boundary portion 220 of the wafer 100. Further, the control unit 7 gradually descends the cutting blade 181 cutting into the wafer 100 at a depth that does not penetrate the concave portion 200 along the Z-axis direction until it reaches a depth at which the concave portion 200 is cut.

[0070] As a result, the entire boundary portion 220 of the wafer 100 is cut by the cutting blade 181. Therefore, as shown in FIG. 7, a ring-shaped cutting groove 230 that penetrates the concave portion 200 is formed in the boundary portion 220 of the wafer 100. As a result, the ring-shaped convex portion 210 is cut off from the concave portion 200 of the wafer 100.

[0071] In this configuration, while rotating the wafer 100, the cutting blade 181 gradually deepens the cutting groove 230 formed in the wafer 100 to cut the convex portion 210 from the concave portion 200 of the wafer 100. Thereby, it is possible to better suppress the occurrence of large chipping in the cutting groove 230 (concave portion 200 and convex portion 210).

[0072] Also, as described above with reference to FIGS. 1(a) and 2(a), the cutting position C1 of the cutting blade 181 in the wafer 100 is set, for example, at a position shifted by 0 degrees or 180 degrees in the circumferential direction of the wafer 100 from the notch 110 on the boundary portion 220.

[0073] For example, assume that the wafer 100 is made of silicon and its front surface 101 and back surface 102 are the 100 planes ((100)) of silicon. In this case, as shown in FIGS. 10(a) and 10(b), the notch 110 is formed, for example, to indicate the 001 direction (

[0001] ) or the 011 direction (

[0011] ). And the cutting position C1 is set at a position shifted by 0 degrees or 180 degrees in the circumferential direction of the wafer 100 from these notches 110. In this example, the surface into which the cutting blade 181 is cut is the 100 plane, and the cutting blade 181 cuts perpendicularly to the 110 direction or 100 direction of the silicon indicated by the notch 110 with respect to the wafer 100. Therefore, it is possible to suppress the occurrence of large chipping in the cutting groove 230 (see FIG. 7).

[0074] Note that in this embodiment, the notch 110 is shown as an example of a mark indicating the crystal orientation of the wafer 100. Regarding this, the mark indicating the crystal orientation of the wafer 100 may be other marks other than the notch, such as an orientation flat.

Explanation of Reference Numerals

[0075] 1: Cutting device, 7: Control unit, 8: Loading device, 9: Unloading device, 10: Base 13: Cutting unit moving mechanism, 14: Gantry column, 16: Z-axis direction moving mechanism 17: Y-axis direction moving mechanism, 18: cutting unit, 20: chuck table, 21: table part, 22: holding surface, 23: frame body, 24: holding member, 25: θ table, 26: ring support part, 28: clamp, 30: X-axis direction moving mechanism, 31: guide rail, 32: ball screw, 33: X-axis table, 34: motor, 80: transfer pad, 81: transfer arm, 82: plate shaft part, 83: support plate part, 85: frame holding part, 90: transfer pad, 91: transfer arm, 92: plate shaft part, 93: support plate part, 95: convex part holding part, 100: wafer, 101: surface, 102: back surface, 103: dicing tape, 105: ring frame, 107: work set, 110: notch, 111: device, 112: division planned line, 160: ball screw, 161: guide rail, 162: motor, 163: support member, 170: ball screw, 171: guide rail, 172: motor, 173: Y-axis table, 181: cutting blade, 182: imaging unit, 200: recess, 201: inner surface, 202: circular bottom surface, 210: convex part, 220: boundary part, 230: cutting groove, 251: table motor, 261: lifting mechanism, 401: suction source, 810: moving mechanism, 910: moving mechanism, C1: cutting position

Claims

1. A method for processing a wafer, comprising forming a ring-shaped cutting groove at the boundary between a concave portion and a convex portion with a cutting blade in order to remove the convex portion from the concave portion of the wafer, the concave portion having a circular bottom surface formed by grinding the central portion into a circular shape and the convex portion being a ring-shaped convex portion disposed outside the concave portion, the method comprising: a holding step of holding the bottom surface of the concave portion of the wafer on the holding surface of a chuck table via a sheet; a positioning step of detecting a mark indicating the crystal orientation of the wafer after the holding step and positioning the cutting position of the cutting blade at the boundary between the concave portion and the convex portion set based on the mark directly below the cutting blade; a cutting step of moving the cutting blade and the chuck table relatively in a direction approaching each other after the positioning step to cut the cutting blade to a depth penetrating the concave portion at the cutting position; a cutting groove forming step of rotating the chuck table after the cutting step to form a ring-shaped cutting groove penetrating the concave portion at the boundary between the concave portion and the convex portion by the cutting blade; The method for processing a wafer, comprising the above steps.

2. A method for processing a wafer, comprising forming a ring-shaped cutting groove at the boundary between a concave portion and a convex portion with a cutting blade in order to remove the convex portion from the concave portion of the wafer, the concave portion having a circular bottom surface formed by grinding the central portion into a circular shape and the convex portion being a ring-shaped convex portion disposed outside the concave portion, the method comprising: a holding step of holding the bottom surface of the concave portion of the wafer on the holding surface of a chuck table via a sheet; a positioning step of detecting a mark indicating the crystal orientation of the wafer after the holding step and positioning the cutting position of the cutting blade at the boundary between the concave portion and the convex portion set based on the mark directly below the cutting blade; a cutting step of moving the cutting blade and the chuck table relatively in a direction approaching each other after the positioning step to cut the cutting blade to a depth not penetrating the concave portion at the cutting position; a cutting groove forming step of rotating the chuck table and moving the cutting blade and the chuck table relatively in a direction approaching each other after the cutting step to form a ring-shaped cutting groove penetrating the concave portion at the boundary between the concave portion and the convex portion by the cutting blade; The method for processing a wafer, comprising the above steps.

3. In the positioning step, the cutting position of the cutting blade is set to a position that is shifted by 0 degrees or 180 degrees in the circumferential direction of the wafer from the mark. The method for processing a wafer according to claim 1 or 2.

Images