Wafer processing method and wafer processing apparatus

Abstract

To provide a wafer processing method and a wafer processing apparatus capable of solving a problem that a residue of a chamfered part existing in a region including a side wall of a first wafer from which the chamfered part is removed and a joint surface of a second wafer becomes a contamination source.SOLUTION: There is provided a wafer processing method for processing a bonded wafer W in which a first wafer 10A and a second wafer 10B are bonded to each other, the wafer processing method including a modified layer forming step of forming a ring-shaped modified layer by applying laser beams through the first wafer 10A while positioning a focal point of the laser beams at an inner side adjacent to a chamfered portion formed at an outer periphery of the first wafer 10A, a chamfered portion removing step of removing the chamfered portion from the first wafer 10A, and a residue removing step of removing residues from a region from which the chamfered portion has been removed after the chamfered portion removing step.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a wafer processing method for processing a bonded wafer formed by bonding a first wafer and a second wafer, and a wafer processing apparatus in which a chamfered portion is removed from the outer periphery of the first wafer of the bonded wafer. [Background technology]

[0002] Wafers have multiple devices such as ICs and LSIs formed on their surface, separated by planned dividing lines. The back surface is ground to a specified thickness, and then the wafer is divided into individual device chips using a dicing machine and laser processing machine. These are then used in electrical equipment such as mobile phones and personal computers.

[0003] Furthermore, a chamfer is formed on the outer periphery of the wafer, and when the back surface of the wafer is ground, the chamfer becomes a sharp knife edge, which can cause cracks to form from the knife edge and penetrate into the device, damaging it or injuring an operator when handling the wafer. Therefore, a technique for removing the chamfer from the wafer has been proposed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-088187 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in a technology in which a first wafer and a second wafer are bonded together to improve device functionality and then the back surface of the first wafer is ground to form a desired thickness, when the chamfered portion is removed from the first wafer, residue of the chamfer remains in the region between the sidewall of the first wafer and the bonding surface of the second wafer, which becomes a source of contamination when subsequent steps are performed, resulting in a problem of degrading the quality of the device.

[0006] The present invention has been made in view of the above-mentioned circumstances, and its main technical object is to provide a wafer processing method and a wafer processing apparatus that can solve the problem that residue of the chamfer that exists in the region including the sidewall of the first wafer from which the chamfer has been removed and the bonding surface of the second wafer becomes a source of contamination in subsequent processes. [Means for solving the problem]

[0007] In order to solve the above-mentioned main technical problem, according to the present invention, there is provided a wafer processing method for processing a bonded wafer formed by bonding a first wafer and a second wafer, the method comprising: a modified layer forming step of irradiating a laser beam that passes through the first wafer and positions the focal point inside adjacent to a chamfered portion formed on the outer periphery of the first wafer, thereby forming a ring-shaped modified layer; and a chamfer removing step of removing the chamfered portion from the first wafer, and a residue removing step of removing residues from the area where the chamfered portion has been removed after the chamfer removing step.

[0008] The chamfered portion removing step preferably involves applying an external force by grinding the top surface of the first wafer to thin it, thereby removing the chamfered portion. The residue removing step may include removing residues with high-pressure air, a tool, or high-pressure water. Furthermore, the method may include a cleaning step of cleaning the bonded wafers after the residue removing step.

[0009] According to the present invention, there is provided a wafer processing apparatus for a bonded wafer formed by bonding a first wafer and a second wafer together, in which a chamfered portion has been removed from the outer periphery of the first wafer, the wafer processing apparatus comprising: holding means for holding the first wafer or the second wafer; and residue removal means for removing residue from the region of the bonded wafer held by the holding means from which the chamfered portion has been removed.

[0010] The residue removal means preferably includes any one of a residue removal means using high-pressure air, a residue removal means using a tool, and a residue removal means using high-pressure water. [Effects of the Invention]

[0011] The wafer processing method of the present invention is a wafer processing method for processing a bonded wafer formed by bonding a first wafer and a second wafer, and includes a modified layer forming step of irradiating a laser beam that passes through the first wafer and positions the focal point of the laser beam inside adjacent to a chamfered portion formed on the outer periphery of the first wafer, thereby forming a ring-shaped modified layer, and a chamfer removing step of removing the chamfered portion from the first wafer, and includes a residue removing step of removing residue from the area where the chamfered portion has been removed after the chamfer removing step.This eliminates the problem of residues adhering to the sidewall of the first wafer after the chamfered portion has been removed and to the bonding surface of the second wafer to which the chamfered portion was bonded being removed and becoming a source of contamination in subsequent steps.

[0012] Furthermore, the wafer processing apparatus of the present invention is a wafer processing apparatus for a bonded wafer formed by bonding a first wafer and a second wafer, in which a chamfered portion has been removed from the outer periphery of the first wafer, and is configured to include holding means for holding the second wafer and residue removal means for removing residue from the region of the first wafer of the bonded wafer held by the holding means from which the chamfered portion has been removed. Therefore, it is possible to appropriately remove residue that has been attached to the sidewall of the first wafer after the chamfered portion has been removed and to the bonding surface of the second wafer to which the chamfered portion was bonded, and the problem of the residue becoming a source of contamination later is solved. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a perspective view of a bonded wafer processed by the processing apparatus of the present embodiment. FIG. [Figure 2] 1A is a perspective view showing an embodiment of a modified layer forming step, and FIG. 1B is a partially enlarged cross-sectional view showing a modified layer formed by the modified layer forming step shown in FIG. 1A. [Figure 3]FIG. 2 is a plan view showing a radial modified layer formed on a first wafer. [Figure 4] FIG. 10 is a perspective view showing how a chamfer is removed from the outer periphery of the first wafer. [Figure 5] 1A is a perspective view showing an embodiment of a chamfered portion removing step performed by a grinding device, and FIG. 1B is a perspective view showing an aspect in which the chamfered portion is removed by the chamfered portion removing step shown in FIG. 1A. [Figure 6] 1 is a perspective view showing a wafer processing apparatus according to an embodiment of the present invention; [Figure 7] FIG. 2(a) is a perspective view showing an embodiment of the residue removal step, and FIG. 2(b) is a partially enlarged side view showing an embodiment of the residue being removed by the residue removal step shown in FIG. [Figure 8] 8(a) is a perspective view showing another embodiment of the residue removing step shown in FIG. 7, and FIG. 8(b) is a partially enlarged side view showing an embodiment in which residues are removed by the residue removing step shown in FIG. 7(a). [Figure 9] FIG. 1 is a perspective view showing an embodiment of a cleaning step. DETAILED DESCRIPTION OF THE INVENTION

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a wafer processing method configured based on the present invention and a wafer processing apparatus suitable for the wafer processing method will be described in detail with reference to the accompanying drawings.

[0015] FIG. 1 shows an example of a bonded wafer W processed by the wafer processing method of this embodiment. The bonded wafer W shown in the figure is formed by bonding a first wafer 10A and a second wafer 10B together. The first wafer 10A is, for example, a silicon (Si) wafer having a diameter of 200 mm and a thickness of 700 μm, and has a plurality of devices 12A formed on a front surface 10Aa, which is partitioned by planned division lines 14A. The first wafer 10A has a front surface 10Aa and a back surface 10Ab, and includes a central effective region 16A in which the devices 12A to be used as products are formed, and a peripheral excess region 18A surrounding the effective region 16A, which has a chamfered portion 17A formed on the outer periphery.

[0016] The second wafer 10B also has a similar configuration to the first wafer 10A, with a chamfered portion 17B formed on the outer periphery, and although not shown, is a silicon wafer on the surface 10Ba facing downward in the drawing, on which a plurality of devices corresponding to the devices 12A of the first wafer 10A are formed and separated by planned division lines, and has a diameter of 200 mm and a thickness of 700 μm.

[0017] The first wafer 10A and the second wafer 10B that constitute the bonded wafer W in this embodiment are integrated by, for example, bonding a surface 10Aa of the first wafer 10A to a surface 10Ba of the second wafer 10B and forming an interface 19 by siloxane bonding. The siloxane bond is an Si-O-Si bond in which silicon (Si) and oxygen (O) are alternately bonded, and since the first wafer 10A and the second wafer 10B are bonded by heat treatment, a strong bonded state is maintained even at high temperatures.

[0018] The bonded wafer W is subjected to the wafer processing method described below in order to remove the chamfered portion 17A of the first wafer 10A.

[0019] (Modified layer forming process) When carrying out the wafer processing method of this embodiment, the above-mentioned bonded wafer W is transported to the laser processing apparatus 20 (only a portion of which is shown) shown in Figure 2(a), and the modified layer formation process described below is carried out.

[0020] The laser processing device 20 includes a chuck table 22 that is rotated by a rotary drive means (not shown), and a laser beam application means 24 that applies a laser beam LB to the bonded wafer W that is suction-held on the chuck table 22. The laser beam application means 24 includes a condenser 26 that positions the focal point of the laser beam LB at a desired position.

[0021] Once the bonded wafer W has been transported to the laser processing apparatus 20, it is placed on the chuck table 22 with the first wafer 10A facing upward and the second wafer 10B facing downward, as shown in FIG. 2(a). Before transporting the bonded wafer W to the laser processing apparatus 20, a protective tape may be attached to the back surface 10Bb of the second wafer 10B, which is positioned below. Once the bonded wafer W has been placed on the chuck table 22, a suction means (not shown) is activated to hold the bonded wafer W by suction. Next, alignment is performed using an alignment means (not shown). By this alignment, the position of the outer periphery where the chamfered portion 17A of the first wafer 10A is formed and the center position of the bonded wafer W are detected, and the height of the upper surface of the back surface 10Ab of the first wafer 10A is detected.The focal point of the laser beam LB is located inside adjacent to the chamfered portion 17A formed on the outer periphery of the first wafer 10A and at a position corresponding to the outer periphery excess region 18A, and the processing position to be irradiated (for example, a position with a radius of 98 mm from the center point of the first wafer 10A) is detected.

[0022] Based on the position information of the processing position detected by the above-described alignment, the chuck table 22 is positioned so that the processing position set on the first wafer 10A of the bonded wafers W is directly below the condenser 26 of the laser beam application means 24, as shown in Fig. 2(a). Next, as can be seen from Fig. 2(b) in addition to Fig. 2(a), the laser beam LB is irradiated from the back surface 10Ab side of the first wafer 10A with the focal point positioned inside the processing position on the first wafer 10A, and the chuck table 22 is rotated in the direction indicated by arrow R1 in Fig. 2(a) to form a ring-shaped modified layer 100 along the inside of the chamfered portion 17A of the first wafer 10A.

[0023] The above-described ring-shaped modified layer 100 is preferably formed of multiple layers arranged vertically, as shown in FIG. 2(b). For example, the modified layer 100 shown in FIG. 2(b) is composed of four modified layers arranged vertically. When forming such a modified layer 100 including multiple layers, first, a laser beam LB is focused at a position corresponding to the peripheral excess region 18A of the first wafer 10A, inside the chamfered portion 17A, and close to the interface 19 (for example, at a depth of 700 μm from the back surface 10Ab), and the chuck table 22 is rotated to form a first ring-shaped modified layer. Then, while rotating the chuck table 22, the focal point is raised toward the rear surface 10Ab (upward) three times, for example, so that the depth from the rear surface 10Ab becomes 500 μm → 300 μm → 150 μm, thereby forming a total of four ring-shaped modified layers along the chamfered portion 17A.

[0024] As described above, by irradiating the laser beam LB with the focal point positioned close to the interface 19 and forming a relatively deep ring-shaped modified layer 100, cracks are formed along the modified layer 100 at a relatively deep position on the front surface 10Aa side of the first wafer 10A, i.e., reaching the interface 19. Note that the depth positions of the layers constituting the modified layer 100 shown in FIG. 2(b) are not based on actual dimensions. Furthermore, the ring-shaped modified layer 100 is not limited to being formed of four layers, and can be appropriately set depending on the thickness of the first wafer 10A, the material constituting the first wafer 10A, the wavelength and output of the laser beam LB irradiated by the laser beam application means 24, etc.

[0025] The laser processing conditions when carrying out the modified layer forming step are set, for example, as follows. Wavelength: 1342nm Repetition frequency: 80kHz Average power: 2.0W Chuck table rotation speed: 60 rpm

[0026] In the modified layer forming step described above, for example, as shown in FIG. 3, a radial modified layer 110 may be formed extending from the region where the ring-shaped modified layer 100 is formed toward the outer circumferential edge where the chamfered portion 17A is formed. The modified layer 110 shown in the figure functions to divide the ring-shaped chamfered portion 17A into smaller portions when removing the chamfered portion 17A. For example, the modified layer 110 is formed by irradiating the first wafer 10A with a laser beam LB under the same laser processing conditions as when forming the modified layer 100 described above, and is formed at multiple evenly spaced locations (six locations in the illustrated embodiment) on the outer periphery of the first wafer 10A. By forming the modified layer 110, the chamfered portion 17A is divided into smaller portions when the chamfered portion 17A is removed from the first wafer 10A in the chamfered portion removing step described below, and the chamfered portion 17A can be efficiently removed.

[0027] (Chamfer removal process) After the modified layer forming step is performed, a chamfer removing step is performed, in which the chamfered portion 17A formed on the outer periphery of the first wafer 10A is removed, starting from the ring-shaped modified layer 100, as shown in FIG. 4. In this embodiment, cracks are formed along the modified layer 100, so that the outer periphery excess region 18A including the chamfered portion 17A can be easily removed starting from the modified layer 100. Note that FIG. 4 conceptually illustrates how the chamfered portion 17A is removed from the bonded wafer W, and the chamfer removing step can be performed in various ways. FIG. 5 illustrates one mode of performing the chamfer removing step.

[0028] When performing the chamfered portion removing step of this embodiment, the bonded wafer W on which the modified layer 100 has been formed by the modified layer forming step described above is transferred to a grinding apparatus 30 (only a portion of which is shown) shown in Fig. 5(a). As shown, the grinding apparatus 30 includes a grinding means 32 for grinding and thinning the bonded wafer W held by suction on a chuck table 31. The grinding means 32 includes a rotating spindle 32a rotated by a rotation drive mechanism (not shown), a wheel mount 32b attached to the lower end of the rotating spindle 32a, and a grinding wheel 32c attached to the lower surface of the wheel mount 32b, and a plurality of grinding stones 32d are annularly arranged on the lower surface of the grinding wheel 32c.

[0029] After the bonded wafer W is transported to the grinding apparatus 30, as shown in Fig. 5(a), it is placed on the chuck table 31 with the second wafer 10B side facing downward, and the suction means (not shown) is activated to hold the bonded wafer W by suction. Next, the rotating spindle 32a of the grinding means 32 is rotated in the direction indicated by arrow R2 in Fig. 5(a) at, for example, 6000 rpm, while the chuck table 31 is rotated in the direction indicated by arrow R3 at, for example, 300 rpm. Then, while grinding water is supplied onto the back surface 10Ab of the first wafer 10A by a grinding water supply means (not shown), the grinding feed means (not shown) is activated to bring the grinding stone 32d into contact with the back surface 10Ab of the first wafer 10A, and the grinding wheel 32c is ground and fed downward as indicated by arrow R4 at a grinding feed rate of, for example, 0.1 µm / sec. As a result, a grinding force is applied as an external force from the back surface 10Ab of the first wafer 10A, and the chamfered portion 17A is removed using the modified layer 100 as the starting point for dividing. At this time, if the radial modified layer 110 is formed in the region corresponding to the peripheral excess region 18A of the first wafer 10A as described above, the appropriately divided chamfered portion 17A' is properly broken from the first wafer 10A, as shown in FIG. 5(b).

[0030] Note that the specific method for performing the chamfered portion removal step is not limited to the method using the grinding apparatus 30 described above. For example, a thin blade (not shown) may be inserted from the side into the interface 19 of the bonded wafers W on which the ring-shaped modified layer 100 has been formed in the laser processing apparatus 20 described above, and the chuck table 22 of the laser processing apparatus 20 holding the bonded wafers W may be rotated to apply an external force by causing the thin blade to advance along the entire circumference, thereby separating the chamfered portion 17A from the first wafer 10A starting from the modified layer 100. Alternatively, high-pressure air may be sprayed from the side toward the interface 19 to apply an external force and remove the chamfered portion 17A.

[0031] Furthermore, the first wafer 10A and the wafer 10B constituting the bonded wafer W are bonded together by a Si-O-Si siloxane bond, and by supplying a fluid such as water, water vapor, mist, or ammonia from the outside to the interface 19 of the bonded wafers W, it is possible to change the Si-O-Si bond to a Si-OH-OH-Si bond and weaken the bonding strength at the outer periphery of the bonded wafers W. Therefore, when performing the chamfered portion removing step, a means for supplying a fluid that weakens the bonding strength is positioned to the side of the bonded wafers W, and the fluid is supplied to the region where the chamfered portions 17A and 17B are bonded at the outer periphery of the bonded wafers W to weaken the bonding strength, thereby ensuring the removal of the chamfered portion 17A in the chamfered portion removing step.

[0032] (Residue removal process) As described above, after removing the region corresponding to the outer peripheral excess region 18A including the chamfered portion 17A of the first wafer 10A constituting the bonded wafer W, the residue removing step described below is carried out. This residue removing step is a step of removing residues from the region after the chamfered portion 17A has been removed, more specifically, a step of removing residues of the chamfered portion 17A from the sidewall 10Ac of the first wafer 10A after the chamfered portion 17A has been removed, as shown in FIG. 5(b), and from the bonding surface 18B of the second wafer 10B to which the removed chamfered portion 17A of the first wafer 10A had been bonded.

[0033] When carrying out the residue removing step of this embodiment, for example, a wafer processing apparatus 40 as shown in Fig. 6 can be used. The illustrated wafer processing apparatus 40 includes at least a holding means 41 that holds the second wafer 10B of the bonded wafer W described above, and a residue removing means 46 that removes residues from the region of the bonded wafer W held by the holding means 41 from which the chamfered portion 17A has been removed.

[0034] In addition to the holding means 41, the wafer processing apparatus 40 includes a rotating shaft 44 that supports the holding means 41, and a rotation drive means 45 that rotates the rotating shaft 44 in the direction indicated by arrow R5, as shown in Fig. 6. The holding means 41 is composed of a suction chuck 42 made of, for example, a breathable material, and a frame 43 that surrounds the suction chuck 42. A suction means (not shown) is connected to the holding means 41, and by operating the suction means, a negative pressure can be generated on the upper surface of the suction chuck 42. An embodiment of a residue removal process using the wafer processing apparatus 40 described above will be described below.

[0035] As shown in FIG. 6, the bonded wafer W from which the chamfered portion 17A of the first wafer 10A has been removed is transported to the illustrated wafer processing apparatus 40. The second wafer 10B is then placed facing downward on the suction chuck 42 of the holding means 41. Next, the tip 46a of the residue removal means 46 is positioned toward the area of ​​the first wafer 10A from which the chamfered portion 17A has been removed. Furthermore, the rotation drive means 45 is operated to rotate the holding means 41 in the direction indicated by arrow R5, as shown in FIG. 7(a), while spraying high-pressure air 47 from the tip 46a of the residue removal means 46 for a predetermined time. The action of the high-pressure air 47 shown in FIG. 7(b) blows away and removes residue adhering to the area of ​​the first wafer 10A from which the chamfered portion 17A has been removed, thereby completing the residue removal process of this embodiment.

[0036] The residue removal means provided in the wafer processing apparatus 40 is not limited to the means for spraying the high-pressure air 47. For example, any suitable tool that functions as a residue removal means can be used. The tool may be, for example, a brush 48 (only the tip side is shown) shown in FIG. 8(a).

[0037] The brush 48 shown in Fig. 8 has bristles 48a and is positioned so that the bristles 48a contact the area of ​​the first wafer 10A of the bonded wafer W held by the holding means 41 from which the chamfered portion 17A has been removed. The bristles 48a preferably have a certain degree of rigidity and can be appropriately selected from, for example, resin bristles, bristles formed of thin metal bundles, and bristles made of natural materials (horsehair, pig hair, etc.). The holding means 41 of the wafer processing device 40 holding the bonded wafer W is rotated in the direction indicated by the arrow R5 to bring the bristles 48a of the brush 48 into contact with the area, thereby removing residue from the sidewall 10Ac of the first wafer 10A and the bonding surface 18B of the second wafer 10B from which the chamfered portion 17A has been removed, as shown in Fig. 8(b).

[0038] Furthermore, the tool constituting the residue removal means of the present invention is not limited to the brush 48 described above, and may be, for example, a grindstone configured to come into contact with the sidewall 10Ac of the first wafer 10A and the bonding surface 18B of the second wafer 10B after the chamfered portion 17A has been removed. By bringing the grindstone into contact with the sidewall 10Ac of the first wafer 10A and the bonding surface 18B of the second wafer 10B after the chamfered portion 17A has been removed and rotating the holding means 41, residues can be removed from the sidewall 10Ac of the first wafer 10A and the bonding surface 18B of the second wafer 10B after the chamfered portion 17A has been removed.

[0039] 7 may spray high-pressure water instead of the high-pressure air 47. By spraying high-pressure water, residues can also be removed from the sidewall 10Ac of the first wafer 10A after the chamfered portion 17A has been removed, and from the bonding surface 18B of the second wafer 10B to which the outer circumferential excess region 18A including the chamfered portion 17A of the first wafer 10A was bonded.

[0040] In the residue removal step described above, the second wafer 10B of the bonded wafer W is placed on the holding means 41 of the wafer processing device 40 and held by suction, but the present invention is not necessarily limited to holding the second wafer 10B. For example, the residue removal step can also be performed by holding the back surface 10Ab side of the first wafer 10A, positioning the residue removal means 46 to the side of the holding means 41, and spraying high-pressure air 47 from the side toward the region where the chamfered portion 17A has been removed.

[0041] (Cleaning process) After the modified layer forming step, chamfered portion removing step, and residue removing step are performed, a cleaning step of cleaning the bonded wafer W may be performed as necessary.

[0042] When performing the cleaning step, for example, after the residue removal step has been performed, cleaning means 50 shown in Fig. 9 is positioned above holding means 41 of wafer processing apparatus 40 that holds bonded wafer W. Cleaning means 50 is equipped with a cleaning head 52 that covers the diameter of suction chuck 42 of holding means 41 and has a plurality of fine holes (not shown) on the underside. By slowly rotating holding means 41 in the direction indicated by arrow R5 while spraying pure water 54 for cleaning from cleaning head 52, not only sidewall 10Ac of first wafer 10A and bonding surface 18B of second wafer 10B after chamfered portion 17A has been removed, but also back surface 10Ab of first wafer 10A. After the bonded wafer W has been cleaned as described above, the pure water 54 for cleaning adhering to the bonded wafer W is blown off by spraying drying air from the cleaning means 50 as needed, or by using a separately prepared air spraying means, thereby completing the drying process of the bonded wafer W. This completes the wafer processing method of this embodiment.

[0043] Although the above-described bonded wafer W is described as being formed by bonding a first wafer 10A and a second wafer 10B together using a siloxane bond, the bonded wafer processed by the wafer processing method of the present invention and the wafer processing apparatus 40 is not limited to wafers bonded together using a siloxane bond. The bonded wafer processed by the present invention may be, for example, a bonded wafer formed by bonding a first wafer 10A and a second wafer 10B together using a SiCN bond based on nitride bonding, by bonding using a TEOS bond that changes tetraethyl orthosilicate molecules into a solid having Si-O-Si bonds, or by heating silicon wafers in an oxygen atmosphere to oxidize the surfaces and bonding using a ThOx bond based on a silicon oxide film (SiO2). Bonded wafers formed by any bonding method can be processed by the wafer processing method and wafer processing apparatus of the present invention, and as described above, the bonding strength can be weakened by supplying a fluid such as water, water vapor, mist, or ammonia to the interface of the bonded wafers from outside the outer periphery. Furthermore, the wafer processing method and wafer processing apparatus of the present invention can be applied to bonded wafers that have been bonded by performing O2 plasma treatment or N2 plasma treatment as pretreatment on the bonding surfaces of the bonded wafers. [Explanation of symbols]

[0044] 10A: First wafer 10Aa: Surface 10Ab: Back 10Ac: Side wall 12A:Device 14A: Planned division line 16A: Effective area 17A, 17A': Chamfered part 18A: Surplus outer area 18B: Joint surface 10B: Second wafer 10Ba: Surface 10Bb: Back side 17B: Chamfered part 19: Interface 20: Laser processing equipment 22: Chuck table 24: Laser beam irradiation means 26: Concentrator 30: Grinding equipment 31: Chuck table 32: Grinding means 32a: Rotating spindle 32b: Wheel mount 32c: Grinding wheel 32d: Grinding wheel 40: Wafer processing equipment 41: Holding means 44: Rotation axis 45: Rotation drive means 46:Residue removal means 47: High pressure air 48: Brush 48a: Hair material 50: Cleaning method 52: Cleaning head 54: Pure water 100, 110: Modified layer

Claims

1. A wafer processing method for processing a bonded wafer formed by bonding a first wafer and a second wafer, comprising: a modified layer forming step of irradiating a laser beam through the first wafer with a focal point positioned inside the chamfered portion formed on the outer periphery of the first wafer to form a ring-shaped modified layer; a chamfer removing step of removing the chamfer from the first wafer; Including, The wafer processing method further comprises, after the chamfered portion removing step, a residue removing step of removing residue from the region where the chamfered portion has been removed.

2. 2. The wafer processing method according to claim 1, wherein the chamfered portion removing step removes the chamfered portion by applying an external force by grinding the upper surface of the first wafer to thin it.

3. 2. The wafer processing method according to claim 1, wherein the residue removal step includes removing residue with high-pressure air, removing residue with a tool, or removing residue with high-pressure water.

4. 2. The wafer processing method according to claim 1, further comprising a cleaning step of cleaning the bonded wafer after the residue removing step.

5. A wafer processing apparatus for a bonded wafer in which a first wafer and a second wafer are bonded together, the apparatus comprising: a holding means for holding a second wafer; a residue removing means for removing residues from the region where the chamfered portion of the first wafer of the bonded wafers held by the holding means has been removed.

6. 6. The wafer processing apparatus according to claim 5, wherein said residue removing means includes any one of means for removing residue by high-pressure air, means for removing residue by a tool, and means for removing residue by high-pressure water.

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