Bonded wafer processing method

Abstract

To simplify a device used for machining and to reduce the time loss of a process.SOLUTION: The present invention is a processing method for removing a chamfered portion of a wafer (side W2) in a bonded wafer (W) in which a base (side W13) and the wafer (side W1) having the chamfered portion (side wall) formed at an outer peripheral edge are bonded to each other. The processing method includes a holding step of holding the base of the bonded wafer by a chuck table (21), an edge trimming step of removing the chamfered portion by rotating the chuck table while causing a blade grindstone (54) to cut into the chamfered portion of the wafer of the bonded wafer held by the chuck table, and a grindstone tip correcting step of correcting a tip shape of the blade grindstone before or after the edge trimming step. In the grindstone tip correction step, the blade grindstone is made to cut into the W12 (upper side) of the wafer of the bonded wafer.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for processing a bonded wafer in which a base and a wafer are bonded together. [Background technology]

[0002] In the semiconductor manufacturing process, when one surface of a wafer having a chamfered portion on its outer periphery is ground, the outer periphery of the wafer becomes knife-edge-like, causing chipping from the outer periphery and resulting in damage to the wafer. To solve this problem, Patent Document 1 discloses an edge trimming process in which the chamfered portion, which could become a knife-edge after the wafer is thinned, is removed from the outer periphery of the wafer before the grinding process. In this edge trimming process, a blade grindstone is used to cut the chamfered portion that will become the outer periphery of the wafer, and the wafer is rotated once to remove the chamfered portion of the wafer with the blade grindstone.

[0003] In the edge trimming process in Patent Document 1, only the wafer bonded to the base is ground so that the blade grinding stone does not cut into the base of the bonded wafer. If edge trimming is performed on multiple bonded wafers in succession, the tip surface (grinding surface) of the blade grinding stone will wear and become uneven. Therefore, as disclosed in Patent Document 2, a possible solution is to correct the tip surface of the blade grinding stone by so-called flat dressing so that the tip surface becomes flat. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-040181 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-069277 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in order to perform flat dressing as in Patent Document 2, a unit dedicated to flat dressing, including a dresser board, etc., must be installed in the processing device where edge trimming is performed, which creates the problem of making the processing device more complex and larger.

[0006] Furthermore, when a unit dedicated to flat dressing is provided in such a processing apparatus, the unit and the table for holding the bonded wafer are installed side by side, which causes a problem of time loss due to the need to move the blade grinding stone back and forth between the bonded wafer and the dedicated unit for flat dressing before and after flat dressing.

[0007] The present invention has been made in view of the above points, and one of its objects is to provide a method for processing a bonded wafer that can simplify the equipment used for processing and reduce time loss in the process. [Means for solving the problem]

[0008] A processing method for a bonded wafer according to one embodiment of the present invention is a processing method for a bonded wafer, which is a bonded wafer formed by bonding a base and a wafer having a chamfered portion formed on an outer periphery thereof, and which removes the chamfered portion from the bonded wafer, the method including: a holding step of holding the base of the bonded wafer on a chuck table; an edge trimming step of rotating the chuck table and cutting a blade grinding wheel into the chamfered portion of the bonded wafer held on the chuck table to remove the chamfered portion; and a grinding wheel tip correction step of cutting the blade grinding wheel into the top surface of the bonded wafer held on the chuck table before or after the edge trimming step to correct the tip shape of the blade grinding wheel. [Effects of the Invention]

[0009] According to the present invention, in order to correct the tip shape of the blade grinding wheel in the grinding wheel tip correction process, the blade grinding wheel is cut into the upper surface of the bonded wafer held on the chuck table. In other words, the tip shape of the blade grinding wheel can be corrected by utilizing the upper surface of the wafer that is removed by grinding to thin the wafer after the edge trimming process. This eliminates the need for a unit such as a dress board used to correct the blade grinding wheel, thereby simplifying the device. Furthermore, when transitioning to the edge trimming process before or after the grinding wheel tip correction process, it is not necessary to move the blade grinding wheel between the unit and the bonded wafer, thereby shortening the movement path of the blade grinding wheel and reducing process time loss. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic perspective view of a processing apparatus and a bonded wafer according to a first embodiment. [Figure 2] FIG. 2A is an explanatory diagram of the holding step of the first embodiment, FIG. 2B is an explanatory diagram of the grinding wheel tip adjustment step of the first embodiment, and FIG. 2C is an explanatory diagram of the edge trimming step of the first embodiment. [Figure 3] FIG. 2 is an explanatory perspective view of a grindstone tip repairing step according to the first embodiment. [Figure 4] FIG. 10 is a perspective view for explaining a groove forming step and a grindstone tip adjusting step according to the second embodiment. [Figure 5] 10A to 10C are explanatory diagrams of a groove forming step and a grindstone tip adjusting step according to the second embodiment. [Figure 6] FIG. 10 is an explanatory perspective view similar to FIG. 4, showing a plurality of grooves according to a modified example of the second embodiment. [Figure 7] FIG. 11 is an explanatory perspective view of a convex portion forming step and a grindstone tip adjusting step according to the third embodiment. [Figure 8] 10A to 10C are explanatory diagrams of a convex portion forming step and a grindstone tip adjusting step according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] [First embodiment] A method for processing a bonded wafer according to a first embodiment will be described below with reference to the accompanying drawings. First, a bonded wafer will be briefly described with reference to Fig. 1. Fig. 1 is a schematic perspective view of a processing apparatus and a bonded wafer according to the first embodiment. As shown in Fig. 1, the bonded wafer W is formed, for example, in a disk shape.

[0012] As shown in FIG. 1, the bonded wafer W includes a wafer W1 and a base W2 that serves as a support substrate for supporting the wafer W1.

[0013] The wafer W1 is formed in a disk shape, and a chamfered portion W13 (see FIG. 2A) is formed on the outer peripheral edge of the wafer W1 from the front surface W11 to the back surface W12, and has a generally semicircular arc shape in cross section. The chamfered portion W13 prevents cracks and dust generation during the manufacturing process of the wafer W1. A pattern P is formed on the front surface W11 of the wafer W1, including a plurality of streets arranged in a grid pattern and devices provided in areas defined by the plurality of streets.

[0014] The base W2 is made of, for example, silicon and has relatively high rigidity. The base W2 is formed in a disk shape that is approximately the same shape as the wafer W1. In the bonded wafer W, the center of the base W2 and the center of the wafer W1 are approximately aligned. The base W2 may be made of sapphire, glass, or the like.

[0015] The wafer W1 and the base W2 are bonded together via an adhesive (not shown) that serves as a bonding member, with the front surface W11 of the wafer W1 and the front surface W21 of the base W2 serving as bonding surfaces. As a result, the back surface W12 of the wafer W1 and the back surface W22 of the base W2 become exposed surfaces of the bonded wafer W. The adhesive is made of, for example, an ultraviolet-curable resin adhesive and has a thickness of 20 to 50 μm. In the processing method of this embodiment, the chamfered portion W13 of the wafer W1 in the bonded wafer W is removed.

[0016] Next, a description will be given of a processing apparatus used in the processing method of the bonded wafer W according to the first embodiment. The processing apparatus 1 shown in Fig. 1 is an apparatus that performs cutting processing on the bonded wafer W held on a chuck table 21 using a blade grindstone 54. By this cutting processing, the chamfered portion W13 of the wafer W1 is removed.

[0017] The processing apparatus 1 according to this embodiment is not limited to the configuration shown below and can be modified as appropriate. For ease of explanation, some components are omitted in FIG. 1. The X-axis, Y-axis, and Z-axis directions shown in FIG. 1 are perpendicular to one another. The X-axis and Y-axis directions are approximately horizontal, and the Z-axis direction is the up-down direction (vertical direction). In addition, in the following drawings, the front side in the X-axis direction may be referred to as the +X side, the back side as the -X side, the left side in the Y-axis direction as the -Y side, the right side as the +Y side, the upper side in the Z-axis direction as the +Z side, and the lower side as the -Z side.

[0018] On the base 11 of the processing device 1, an X-axis movement mechanism 13 (processing feed unit) is arranged to move the chuck table 21 in the X-axis direction, which is the cutting direction of the blade grindstone 54 (processing feed direction).

[0019] The X-axis movement mechanism 13 has a pair of guide rails 14 arranged on the base 11 and parallel to the X-axis direction, and a motor-driven X-axis table 15 slidably installed on the pair of guide rails 14. A nut portion (not shown) is formed on the underside of the X-axis table 15, and a feed screw 16 is threadedly engaged with this nut portion. An X-axis servo motor 18 connected to one end of the feed screw 16 is rotated, whereby the chuck table 21 can be fed for processing along the pair of guide rails 14 in the X-axis direction.

[0020] A chuck table 21 for holding the bonded wafer W and a rotation mechanism 22 are provided on the X-axis table 15. The chuck table 21 has an upper surface that is circular in plan view and serves as a holding surface 23. An annular groove 24 having an outer diameter smaller than the outer diameter of the bonded wafer W is formed in the holding surface 23, and a suction source 25 (see FIG. 2A) that generates negative pressure is connected to the annular groove 24. Therefore, the negative pressure generated on the holding surface 23 via the suction source 25 causes the back surface W22 of the base W2 of the bonded wafer W to be sucked and held onto the holding surface 23. A solenoid valve 26 (see FIG. 2A) is provided in a flow path connecting the annular groove 24 and the suction source 25.

[0021] The rotation mechanism 22 includes a shaft 27 and a direct drive motor 28 disposed below the chuck table 21. The shaft 27 is a rotation axis whose axial direction is the Z-axis direction (up and down direction), and extends downward from the lower surface of the chuck table 21. The direct drive motor 28 has a built-in encoder that detects the rotation angle of the shaft 27, and is provided so as to be able to rotate the chuck table 21 via the shaft 27 around the center of the holding surface 23 as an axis.

[0022] A gate-shaped upright wall portion 12 is provided on the upper surface of the base 11 so as to straddle the movement path of the chuck table 21. The upright wall portion 12 is provided with a Y-axis movement mechanism 31 (index feed unit) that moves the processing unit 51 in the Y-axis direction perpendicular to the X-axis direction on a horizontal plane parallel to the holding surface 23, and a Z-axis movement mechanism 41 (cutting feed unit) that moves the processing unit 51 in the Z-axis direction.

[0023] The Y-axis movement mechanism 31 has a pair of guide rails 34 that are arranged in front of the upright wall portion 12 and are parallel to the Y-axis direction, and a Y-axis table 35 that is slidably installed on the pair of guide rails 34. A nut portion (not shown) is formed on the back side of the Y-axis table 35, and a feed screw 36 is threadedly engaged with the nut portion. A Y-axis servo motor 37 is connected to one end of the feed screw 36 for the Y-axis table 35. The feed screw 36 is rotated by the Y-axis servo motor 37, thereby moving the Y-axis table 35, the Z-axis movement mechanism 41, and the processing unit 51 in the Y-axis direction along the guide rails 34.

[0024] The Z-axis movement mechanism 41 has a pair of guide rails 44 that are arranged on the Y-axis table 35 and are parallel to the Z-axis direction, and a Z-axis table 45 that is slidably installed on the pair of guide rails 44. A spindle housing 52 of a processing unit 51 is connected to the lower end of the Z-axis table 45. A nut portion (not shown) is formed on the back side of the Z-axis table 45, and a feed screw 46 is threadedly engaged with the nut portion. A Z-axis servo motor 47 is connected to one end of the feed screw 46 for the Z-axis table 45. The feed screw 46 is rotated by the Z-axis servo motor 47, thereby moving the Z-axis table 45 and the processing unit 51 in the Z-axis direction along the guide rails 44 (up and down).

[0025] In the processing unit 51, a spindle 53 is rotatably supported by a spindle housing 52, and a blade grindstone 54 is attached to the tip (the end on the -Y side) of the spindle 53. The blade grindstone 54 is formed in a disk shape with diamond abrasive grains bound together with a bonding agent. The blade grindstone 54 is rotated via the spindle 53, and the direction of its rotation axis is set parallel to the Y axis direction.

[0026] Here, when the blade grinding wheel 54 is subjected to an edge trimming process (see FIG. 2C ) as described below, cutting debris tends to accumulate on one side of the blade grinding wheel 54, causing greater wear of the blade grinding wheel 54 on that side and uneven wear. For this reason, the processing method of the first embodiment includes, in addition to the edge trimming process, a grinding wheel tip correction process for flattening the tip surface of the unevenly worn blade grinding wheel 54 and making the edge of the blade grinding wheel 54 perpendicular.

[0027] A processing method for a bonded wafer W according to the first embodiment will be described below with reference to Fig. 2 and Fig. 3. Fig. 2A is an explanatory diagram of the holding step according to the first embodiment, Fig. 2B is an explanatory diagram of the grinding wheel tip repair step according to the first embodiment, and Fig. 2C is an explanatory diagram of the edge trimming step according to the first embodiment. Fig. 3 is an explanatory perspective view of the grinding wheel tip repair step according to the first embodiment.

[0028] In the processing method for a bonded wafer W in the first embodiment, a holding step, a grinding wheel tip correction step, and an edge trimming step are performed. The grinding wheel tip correction step can be performed either before or after the edge trimming step, but here, the case where it is performed before the edge trimming step will be described.

[0029] 2A, a holding step is first performed in the processing method of the first embodiment. In the holding step, the bonded wafer W is placed on the holding surface 23 of the chuck table 21. Thereafter, the electromagnetic valve 26 is opened, and negative pressure generated by the suction source 25 is applied to the back surface W22 of the base W2 of the bonded wafer W through the annular groove 24 in the chuck table 21. As a result, the base W2 of the bonded wafer W is suction-held by the chuck table 21.

[0030] After the holding step, a grindstone tip adjustment step is performed as shown in Fig. 2B. In the grindstone tip adjustment step, the wafer W1 of the bonded wafer W that will be immediately subjected to an edge trimming step is used to perform so-called flat dressing on the tip of the blade grindstone 54.

[0031] Specifically, in the grindstone tip adjustment process, the X-axis movement mechanism 13 and the Y-axis movement mechanism 31 are driven to move the blade grindstone 54 slightly to the -Y side from the end of the wafer W1 on the -Y side of the bonded wafer W held on the chuck table 21. Thereafter, the Z-axis movement mechanism 41 is driven to lower the processing unit 51, and the tip, which will be the lower end of the blade grindstone 54, is positioned at a height at which it contacts the back surface W12 (upper surface) of the wafer W1, in other words, slightly below the back surface W12.

[0032] Next, while the blade grinding stone 54 is rotated at high speed, the Y-axis movement mechanism 31 is driven to move the blade grinding stone 54 in the +Y-axis direction, causing the tip of the blade grinding stone 54 to cut into the back surface W12 of the wafer W1 of the bonded wafer W held on the chuck table 21. As a result, as shown in Fig. 3, the back surface W12 of the wafer W1 is cut linearly and parallel to the direction of the rotation axis of the blade grinding stone 54, and the tip of the blade grinding stone 54 is flat-dressed. Therefore, even if the tip side of the blade grinding stone 54, which will undergo the edge trimming process from now, is unevenly worn, the edge of the blade grinding stone 54 is made square and the tip surface is flattened, and the tip shape of the blade grinding stone 54 is corrected.

[0033] The blade grinding wheel 54 waits at a position immediately after the wafer W1 has been flat-dressed by performing the grinding wheel tip correction process, that is, at a position near the +Y side end of the wafer W1 of the bonded wafer W shown by the dashed line in Figure 2B.

[0034] After the grindstone tip correction process is performed, the edge trimming process is performed using the blade grindstone 54 whose tip shape has been corrected, as shown in Fig. 2C. In the edge trimming process, the moving mechanisms 13, 31, and 41 are driven from the standby state as described above, and the blade grindstone 54 is positioned directly above the +Y side end portion, which is the outer periphery of the wafer W1 of the bonded wafer W held on the chuck table 21. At this time, when viewed from the Z axis direction, the diameter position of the wafer W1 parallel to the Y axis direction and the rotation center position of the blade grindstone 54 coincide with each other.

[0035] Next, while the blade grindstone 54 is being rotated at high speed, the Z-axis movement mechanism 41 is driven to lower the processing unit 51, and the blade grindstone 54 cuts into the chamfered portion W13 on the +Y side of the wafer W1. In this cutting, the lower end of the blade grindstone 54 is positioned between the layers of the adhesive member (not shown) between the wafer W1 and the base W2 so that the lower end of the blade grindstone 54 is not in contact with the base W2 and is located below the front surface W11 (lower surface) of the wafer W1. In addition to the method of positioning the blade grinding wheel 54 above the wafer W1 as described above and then lowering it to a predetermined height, the blade grinding wheel 54 may also be positioned by lowering it to a predetermined height outside the outer periphery of the wafer W1 in the X-axis direction, and then moving the chuck table 21 in the X-axis direction to slide the blade grinding wheel 54 into the wafer W1.

[0036] Next, the rotation mechanism 22 rotates the chuck table 21, and the blade grindstone 54 cuts into the entire chamfered portion W13 of the wafer W1 in the bonded wafer W held on the chuck table 21. In other words, the entire chamfered portion W13 of the wafer W1 is cut into a circular shape by the rotating blade grindstone 54, and the chamfered portion W13 of the wafer W1 is removed. By removing the chamfered portion W13, the outer periphery of the wafer W1 does not remain in a knife-edge shape after grinding, and the occurrence of cracks in the outer periphery of the wafer W1 is prevented.

[0037] According to the first embodiment, in the grindstone tip adjustment process, the blade grindstone 54 cuts into the wafer W1 of the bonded wafer W held on the chuck table 21. Therefore, the top surface of the wafer W1, which is thinned by grinding in a process after the grindstone tip adjustment process and the edge trimming process, can be used to adjust the tip shape of the blade grindstone 54. This makes it possible to omit a unit such as a dress board used to adjust the blade grindstone 54, thereby simplifying the configuration of the processing apparatus 1.

[0038] Furthermore, the position of the blade grinding wheel 54 can be brought closer to the edge of the wafer W1 on the +Y side at the end of the grinding wheel tip adjustment process and the start of the edge trimming process. This eliminates the need to move the blade grinding wheel 54 to the unit, as compared to a configuration using a unit such as a dress board, and shortens the movement path of the blade grinding wheel 54, thereby reducing time loss in the process.

[0039] Incidentally, even when the grindstone tip repairing process is performed after the edge trimming process, the position of the blade grindstone 54 can be brought close to the end of the +Y side or the -Y side of the wafer W1 at the end of the edge trimming process and the start of the grindstone tip repairing process. Therefore, time loss in the process can be reduced in the same manner as described above. When the grindstone tip repairing process is performed after the edge trimming process, the edge trimming process can be performed on the wafer W1 of the bonded wafer W to be processed next, using the blade grindstone 54 whose tip shape has been repaired.

[0040] Next, other embodiments of the present invention will be described. In the following description, the same reference numerals may be used to designate components that are the same as or equivalent to those in the embodiments described before the embodiment, and the description thereof may be omitted or simplified.

[0041] [Second embodiment] A second embodiment of the present invention will be described with reference to Figs. 4 and 5. Fig. 4 is an explanatory perspective view of the groove forming step and the grinding wheel tip repair step of the second embodiment. Fig. 5 is an explanatory view of the groove forming step and the grinding wheel tip repair step of the second embodiment. In the second embodiment, before the grinding wheel tip repair step of the first embodiment, a groove forming step is carried out to form multiple grooves W15 on the back surface W12 (top surface) of the wafer W1, as shown in Figs. 4 and 5.

[0042] In the second embodiment, the groove forming step involves lowering the blade grindstone 54, which rotates at high speed, at predetermined intervals to cut into the wafer W1 of the bonded wafer W held on the chuck table 21 in the Y-axis direction, which is the direction of the rotation axis of the blade grindstone 54. As a result, a plurality of grooves W15 are formed side by side in the Y-axis direction on the back surface W12 (top surface) of the wafer W1. The extension directions of the plurality of grooves W15 are parallel to the X-axis direction and perpendicular to (intersect with) the direction of the rotation axis (Y-axis) of the blade grindstone 54.

[0043] In forming each groove W15, after the rotating blade grindstone 54 has cut into the back surface W12 of the wafer W1, the length of the groove W15 may be set according to the cutting depth without moving the chuck table 21 in the X-axis direction. Alternatively, after the rotating blade grindstone 54 has cut into the back surface W12 of the wafer W1, the chuck table 21 may be moved in the X-axis direction to extend the length of the groove W15.

[0044] In the second embodiment, after the groove forming step is performed, a grindstone tip dressing step is performed. The grindstone tip dressing step of the second embodiment is performed in the same manner as the grindstone tip dressing step of the first embodiment, except that multiple grooves W15 are formed in the wafer W1. Therefore, after the tip (lower end) of the blade grindstone 54 is positioned at a height where it contacts the back surface W12 (upper surface) of the wafer W1, the blade grindstone 54 is moved in the Y-axis direction so as to pass through the multiple grooves W15 formed in the wafer W1. Note that the Y-axis direction, which is the movement direction of the blade grindstone 54 in the grindstone tip dressing step, is a direction that intersects with the grooves W15 and is parallel to the direction of the rotation axis of the blade grindstone 54.

[0045] The second embodiment also provides the same effects as the first embodiment, and in addition, the blade grindstone 54 can be flat-dressed on the uneven surface created by the multiple grooves W15 in the grindstone tip correction process. Therefore, the resistance and friction when the tip of the blade grindstone 54 contacts the back surface W12 of the wafer W1 and moves can be increased, making it easier to flatten the tip surface of the blade grindstone 54.

[0046] FIG. 6 is an explanatory perspective view similar to FIG. 4, showing a plurality of grooves according to a modification of the second embodiment. While the plurality of grooves W15 described above extend parallel to the X-axis direction, as shown in FIG. 6, a plurality of grooves W16 may extend in a direction inclined at a predetermined angle relative to the X-axis direction. In the modification of FIG. 6, grooves W16 slightly inclined clockwise relative to the X-axis direction and grooves W16 slightly inclined counterclockwise relative to the X-axis direction are alternately arranged when viewed from above. The grooves W16 of the modification of FIG. 6 also form an uneven surface on the back surface W12 of the wafer W1, allowing the blade grinding wheel 54 to be flat-dressed.

[0047] [Third embodiment] A third embodiment of the present invention will be described with reference to Figs. 7 and 8. Fig. 7 is an explanatory perspective view of the convex portion forming step and the grinding wheel tip repair step of the third embodiment. Fig. 8 is an explanatory view of the convex portion forming step and the grinding wheel tip repair step of the third embodiment. In the third embodiment, before the grinding wheel tip repair step of the first embodiment, a convex portion forming step is carried out to form one convex portion W17 on the back surface W12 (upper surface) of the wafer W1, as shown in Figs. 7 and 8.

[0048] In the third embodiment, the convex portion forming step involves cutting two cut grooves W18 into the Y-axis direction central portion of the back surface W12 of the wafer W1 of the bonded wafer W held on the chuck table 21 by a blade grindstone 54 rotating at high speed. The two cut grooves W18 extend in the X-axis direction so that both ends in the extension direction reach the outer periphery of the wafer W1, and are also formed at a predetermined distance in the Y-axis direction. Thus, one convex portion W17 is formed between the two cut grooves W18 on the back surface W12 (top surface) of the wafer W1. The extension direction of the convex portion W17 is parallel to the X-axis direction and perpendicular to the rotation axis direction (Y-axis direction) of the blade grindstone 54.

[0049] In the third embodiment, after the groove forming step is performed, a grindstone tip adjustment step is performed. In the grindstone tip adjustment step of the third embodiment, the X-axis moving mechanism 13 and the Y-axis moving mechanism 31 are driven to move the blade grindstone 54 slightly toward the -X side from the -X side end of the wafer W1 of the bonded wafer W held on the chuck table 21. Thereafter, the Z-axis moving mechanism 41 is driven to lower the processing unit 51, and the tip of the blade grindstone 54 is positioned at a height where it contacts the upper surface of the convex portion W17 of the wafer W1.

[0050] Next, while the blade grindstone 54 is being rotated at high speed, the chuck table 21 is driven by the X-axis movement mechanism 13, and the chuck table 21 is moved in the −X-axis direction relative to the blade grindstone 54. This movement causes the tip of the blade grindstone 54 to cut into the convex portion W17 formed on the back surface W12 of the wafer W1 of the bonded wafer W held on the chuck table 21, thereby flat-dressing the tip of the blade grindstone 54. Note that in the grindstone tip adjustment process, the X-axis direction, which is the movement direction of the blade grindstone 54, is the extension direction of the convex portion W17 and is perpendicular to the direction of the rotation axis of the blade grindstone 54.

[0051] 8, the width of the convex portion W17 is preferably smaller than the width of the blade grindstone 54. Because the blade grindstone 54 is unevenly worn during the edge trimming process, the shape of the tip of the blade grindstone 54 can be corrected by bringing the upper surface of the convex portion W17 into contact with the tip of an unworn or less worn portion of the blade grindstone 54. In Figure 8, the blade grindstone 54 protrudes from the convex portion W17 in the +Y direction, but the tip shape of the blade grindstone 54 may be modified at a position where the center of the thickness of the blade grindstone 54 coincides with the center of the width of the convex portion W17.

[0052] The third embodiment also achieves the same effects as the first embodiment, and in addition, the blade grindstone 54 can be flat-dressed on the upper surface of the protrusion W17, which becomes rib-like in the grindstone tip dressing process. In the third embodiment, when the edge trimming process is started after the grindstone tip dressing process is completed, the chuck table 21 is rotated 90°, and the position of the blade grindstone 54 is relatively moved from near the end on the +X side of the wafer W1 to near the end on the +Y side. Therefore, even in the third embodiment, although some time is required to rotate the chuck table 21, the movement trajectory of the blade grindstone 54 can be shortened, thereby reducing time loss in the process.

[0053] The present invention is not limited to the above-described embodiment, and various modifications can be made to the present invention. In the above-described embodiment, the size and shape shown in the accompanying drawings are not limited to these, and can be modified as appropriate within the scope of the effects of the present invention. In addition, the present invention can be modified as appropriate without departing from the scope of the object of the present invention.

[0054] For example, in the grindstone tip adjustment process in the first and second embodiments, the direction of movement of the rotating blade grindstone 54 only needs to be parallel to the Y-axis direction, which is the direction of the rotation axis, and it may be moved in the -Y-axis direction or moved back and forth in the Y-axis direction. [Industrial Applicability]

[0055] As described above, the present invention has the effect of simplifying the configuration of a processing apparatus for edge trimming a bonded wafer and reducing time loss in processes before or after the edge trimming step. [Explanation of symbols]

[0056] 21: Chuck table 54: Blade grinding stone W: Bonded wafer W1: Wafer W12: Back side (top side) W13: Chamfered part W15: Groove W16: Groove W17: Convex part W2: Base

Claims

1. A processing method for a bonded wafer, which is formed by bonding a base and a wafer having a chamfered portion formed on an outer periphery thereof, comprising removing the chamfered portion from the wafer, the method comprising: a holding step of holding the base of the bonded wafer on a chuck table; an edge trimming step of rotating the chuck table and cutting a blade grindstone into the chamfered portion of the bonded wafer held on the chuck table to remove the chamfered portion; and a grindstone tip correction step of cutting the blade grindstone into the upper surface of the bonded wafer held on the chuck table before or after the edge trimming step to correct the tip shape of the blade grindstone.

2. a groove forming step of cutting the blade grindstone into the wafer and forming a plurality of grooves in the direction of the rotation axis of the blade grindstone before the grindstone tip adjustment step; 2. The method for processing a bonded wafer according to claim 1, wherein in the grinding wheel tip adjustment step, the blade grinding wheel is moved in the direction of the rotation axis of the blade grinding wheel, which is a direction intersecting the groove formed in the groove forming step, to a height such that the tip of the blade grinding wheel contacts the upper surface of the wafer.

3. a protrusion forming step of forming a protrusion on the upper surface of the wafer, the protrusion extending in a direction perpendicular to the direction of the rotation axis of the blade grindstone, before the grindstone tip repair step; 2. The method for processing a bonded wafer according to claim 1, wherein in the grindstone tip adjustment step, the blade grindstone is moved in a direction perpendicular to the rotation axis relative to the chuck table at a height such that the tip of the blade grindstone contacts the upper surface of the convex portion formed in the convex portion formation step.

Images