Processing device of wafer

Abstract

To provide a processing device of a wafer capable of completely removing a chamfered portion from a wafer having a modified layer formed thereon in a ring shape.SOLUTION: A processing device 2 of a wafer includes: a holding table 4 holding a wafer 52; rotating means 6 rotating the holding table 4 to generate centrifugal force at a chamfered portion 64; and external force applying means 8 applying external force to the chamfered portion 64 when the rotational speed of the holding table 4 reaches a predetermined value. The external force applying means 8 stimulates the chamfered portion 64, and the chamfered portion 64 is scattered and removed by the centrifugal force.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a wafer processing device for removing a chamfered portion from a wafer on which a modified layer has been formed along the chamfered portion. [Background technology]

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

[0003] Because a chamfer is formed on the outer periphery of a wafer, when the backside of the wafer is ground to thin it, the chamfer becomes a sharp knife-edge. This requires operators to be extra careful when handling the wafer. Furthermore, when the chamfer becomes a sharp knife-edge, cracks tend to form from the outer periphery of the wafer to the inside, increasing the risk of device damage. The above-mentioned problem can occur not only with a single wafer, but also with a bonded wafer consisting of two stacked wafers.

[0004] Therefore, the present applicant has proposed a technology in which, before grinding the back surface of the wafer, the focal point of a laser beam having a wavelength that is transparent to the wafer is positioned inside the chamfered portion, and the laser beam is irradiated onto the wafer, forming a ring-shaped modified layer inside the wafer and removing the chamfered portion (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-88187 Summary of the Invention [Problem to be solved by the invention]

[0006] However, there are cases where the chamfered portion is not completely removed from the outer periphery of the wafer and a small portion remains, which can cause problems such as the remaining portion falling off in a later process and becoming a source of contamination, or causing chipping of device chips when the wafer is divided into individual device chips.

[0007] An object of the present invention is to provide a wafer processing apparatus capable of completely removing a chamfered portion from a wafer on which a ring-shaped modified layer is formed. [Means for solving the problem]

[0008] According to the present invention, the following wafer processing apparatus is provided to solve the above problems: "A wafer processing device for removing a chamfered portion from a wafer having an effective area including a device area in which a plurality of devices are partitioned by planned division lines and an outer peripheral excess area in which a chamfered portion surrounding the effective area is formed, by positioning a focal point of a laser beam having a wavelength that is transparent to the wafer within the outer peripheral excess area and irradiating the wafer with the laser beam, the wafer having a modified layer formed along the chamfered portion, a holding table for holding a wafer; a rotating means for rotating the holding table to generate centrifugal force on the chamfered portion; an external force applying means for applying an external force to the chamfered portion when the rotation speed of the holding table reaches a predetermined value; The external force applying means applies a stimulus to the chamfered portion, and the chamfered portion is scattered and removed by centrifugal force.

[0009] Preferably, the external force applying means is a lever having a force point, a fulcrum, and a point of action, the fulcrum being formed on the outer periphery of the holding table, the force point being formed by a weight, and a claw being formed at the point of action that applies a stimulus to the chamfered portion, so that when the centrifugal force generated by the rotation of the holding table causes the weight to move to the outer periphery and the rotation speed reaches a predetermined value, the claw at the point of action applies a stimulus to the chamfered portion, causing the chamfered portion to be scattered and removed by the centrifugal force.

[0010] It is desirable that the weight is provided with a spring that resists centrifugal force, and when the rotational speed of the holding table reaches a predetermined value, the weight overcomes the resistance of the spring and moves to the outer periphery, causing the claws at the point of action to stimulate the chamfered portion, scattering and removing the chamfered portion by centrifugal force.

[0011] A magnet that resists centrifugal force is disposed on the weight, and when the rotation speed of the holding table reaches a predetermined value, the weight overcomes the resistance of the magnet and moves to the outer periphery, causing the claws at the point of action to stimulate the chamfered portion, causing the chamfered portion to be scattered and removed by centrifugal force.

[0012] The external force applying means preferably includes a nozzle for spraying a fluid onto the chamfered portion, and when the rotational speed of the holding table reaches a predetermined value, the fluid sprayed from the nozzle stimulates the chamfered portion, scattering and removing the chamfered portion by centrifugal force.

[0013] The predetermined rotation speed of the holding table may be 3000 rpm. [Effects of the Invention]

[0014] The wafer processing apparatus of the present invention comprises: A wafer processing device for removing a chamfered portion from a wafer having a modified layer formed along the chamfered portion by positioning a focal point of a laser beam having a wavelength that is transparent to the wafer within the peripheral excess region, the laser beam having a wavelength that is transparent to the wafer, the focal point of the laser beam being located within the peripheral excess region, the wafer having a useful area including a device region in which a plurality of devices are partitioned by planned division lines and a chamfered portion that surrounds the useful area, the wafer being processed according to the present invention. a holding table for holding a wafer; a rotating means for rotating the holding table to generate centrifugal force on the chamfered portion; an external force applying means for applying an external force to the chamfered portion when the rotation speed of the holding table reaches a predetermined value; The external force applying means applies a stimulus to the chamfered portion, scattering and removing it by centrifugal force, so that the chamfered portion can be completely removed from the wafer on which the ring-shaped modified layer is formed, thereby eliminating problems such as the remaining portion falling off in subsequent processes and becoming a source of contamination, or causing chipping of device chips when the wafer is divided into individual device chips. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a perspective view of a wafer processing apparatus according to the present invention; [Figure 2] FIG. 2 is a schematic diagram of the external force applying means shown in FIG. 1. [Figure 3] FIG. 3 is a schematic diagram showing a first modified example of the external force application means shown in FIG. 2. [Figure 4] FIG. 3 is a schematic diagram showing a second modified example of the external force application means shown in FIG. 2. [Figure 5] 10A and 10B are schematic diagrams showing other forms of external force application means. [Figure 6] (a) Perspective view of a single wafer, (b) Partial cross-sectional view of the wafer shown in (a). [Figure 7] (a) A perspective view of the bonded wafer, (b) A partial cross-sectional view of the wafer shown in (a). [Figure 8] FIG. 2 is a schematic diagram showing a state in which a bonded wafer is held on a chuck table of a laser processing apparatus. [Figure 9] FIG. 4 is a schematic diagram showing a state in which a modified layer is being formed. [Figure 10] (a) Partial cross-sectional view of a bonded wafer on which a Type 1 modified layer is formed, (b) Partial cross-sectional view of a bonded wafer on which a Type 2 modified layer is formed, (c) Partial cross-sectional view of a bonded wafer on which a Type 3 modified layer is formed, (d) Partial cross-sectional view of a bonded wafer on which a Type 4 modified layer is formed. [Figure 11] FIG. 10 is a plan view of a wafer on which a ring-shaped modified layer and a radial modified layer are formed. [Figure 12] FIG. 2 is a schematic diagram showing a state in which a bonded wafer is held on the holding table shown in FIG. 1. [Figure 13]FIG. 4 is a schematic diagram showing a state in which a chamfered portion is being removed from a first wafer. [Figure 14] FIG. 10 is a perspective view of the bonded wafers with the chamfer removed from the first wafer. DETAILED DESCRIPTION OF THE INVENTION

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a wafer processing apparatus according to the present invention will now be described with reference to the drawings.

[0017] (Wafer processing equipment 2) Referring to FIG. 1, the wafer processing device 2 includes a holding table 4 for holding the wafer, a rotation means 6 for rotating the holding table 4 to generate centrifugal force on the chamfered portion, and an external force applying means 8 for applying an external force to the chamfered portion when the rotation speed of the holding table 4 reaches a predetermined value.

[0018] (Holding table 4) The holding table 4 includes a circular suction chuck 10 with an exposed top surface and a frame member 12 that surrounds the suction chuck 10. The suction chuck 10 is made of a porous material such as porous ceramics. The suction chuck 10 is connected to a suction means (not shown). In the holding table 4, the suction means generates a suction force on the top surface of the suction chuck 10, thereby suction-holding a wafer placed on the top surface of the suction chuck 10.

[0019] (Rotation means 6) The rotation means 6 is equipped with a motor 14 having a rotation shaft 14a connected to the lower center of the holding table 4, and the motor 14 rotates the holding table 4 about an axis in the vertical direction. In addition, an elevation means 16, which may be composed of an actuator such as an air cylinder, is attached to the outer periphery of the motor 14. The elevation means 16 raises and lowers the holding table 4 together with the motor 14.

[0020] (External force applying means 8) 1 and 2, the external force application means 8 can be configured as a lever having a force point 18, a fulcrum 20, and a point of action 22. As shown in FIG. 1, a plurality of levers (three in the illustrated embodiment) serving as the external force application means 8 are provided on the outer periphery of the frame member 12 of the holding table 4 at intervals in the circumferential direction.

[0021] The external force application means 8 of this embodiment has a main shaft 24 extending in the vertical direction. As shown in FIG. 2 , a fulcrum 20 protrudes from the middle of the main shaft 24 radially inward of the holding table 4, and is connected to the frame member 12 of the holding table 4 by a pin 26. That is, the fulcrum 20 is formed on the outer periphery of the holding table 4. In addition, a force point 18 is formed by a weight extending from the lower part of the main shaft 24 radially outward of the holding table 4. The point of action 22 extends from the upper part of the main shaft 24 radially inward of the holding table 4. A claw 22a is formed at the tip of the point of action 22 to apply a stimulus to the chamfered portion of the wafer. The claw 22a is formed in a triangular shape that narrows radially inward of the holding table 4 when viewed from above.

[0022] When the holding table 4 is not rotating, the external force applying means 8 is located at the position shown by the solid line in Fig. 2. On the other hand, when the holding table 4 is rotating, the centrifugal force generated by the rotation of the holding table 4 moves the weight at the force point 18 to the outer periphery (the radially outer side of the holding table 4). When the rotation speed of the holding table 4 reaches a predetermined value (for example, 3000 rpm), the external force applying means 8 oscillates in the direction shown by the arrow R1 toward the position shown by the two-dot chain line in Fig. 2, and the claws 22a of the action point 22 apply a stimulus to the chamfered portion of the wafer.

[0023] The external force application means 8 is not limited to the form shown in Fig. 2, and for example, as shown in Fig. 3, a spring 28 that resists the centrifugal force associated with the rotation of the holding table 4 may be disposed on the weight at the force point 18. Alternatively, as shown in Fig. 4, a magnet 30 that resists the centrifugal force associated with the rotation of the holding table 4 may be disposed on the weight at the force point 18. That is, a first magnet 30a may be disposed on the weight at the force point 18, and a second magnet 30b that is attracted to the first magnet 30a may be disposed on the frame member 12 of the holding table 4.

[0024] The external force applying means 8 may also have a configuration as shown in FIG. 5. The external force applying means 8 shown in FIG. 5 includes a nozzle 32 that sprays fluid F onto the chamfered portion of the wafer, a fluid supply source 34 for supplying fluid F to the nozzle 32, a valve 38 arranged in a pipeline 36 between the fluid supply source 34 and the nozzle 32, and a controller 40 that controls the opening and closing of the valve 38. In the external force applying means 8 shown in FIG. 5, the controller 40 closes the valve 38 until the rotation speed of the holding table 4 reaches a predetermined value. When the rotation speed of the holding table 4 reaches the predetermined value, the controller 40 opens the valve 38 and supplies fluid F from the fluid supply source 34 to the nozzle 32. The fluid F sprayed from the nozzle 32 then stimulates the chamfered portion. Examples of the fluid F sprayed onto the chamfered portion of the wafer include 1: air, 2: water, and 3: two fluids consisting of air and water.

[0025] As shown in FIG. 1 , the wafer processing apparatus 2 further includes a cover member 42 that surrounds the periphery of the holding table 4. The cover member 42 includes a ring-shaped bottom plate 44, an outer peripheral wall 46 that extends upward from the outer peripheral edge of the bottom plate 44, an inner peripheral wall 48 that extends upward from the inner peripheral edge of the bottom plate 44, and a plurality of legs 50 that extend downward at intervals in the circumferential direction from the outer peripheral edge of the lower surface of the bottom plate 44. A circular opening 46a is provided at the upper part of the outer peripheral wall 46. The diameter of the outer peripheral wall 46 gradually decreases toward the top, but the diameter of the opening 46a is slightly larger than the diameter of the frame member 12 of the holding table 4.

[0026] (single wafer 52) 6(a) and 6(b) show a disk-shaped wafer 52 that can be processed by the wafer processing apparatus 2 described above. The wafer 52 can be formed from an appropriate semiconductor material such as silicon. The wafer 52 has, for example, a diameter of 300 mm and a thickness of approximately 300 μm. The surface 52a of the wafer 52 has an effective area 58 including a device region in which multiple devices 54, such as ICs and LSIs, are defined by lattice-shaped division lines 56, and a peripheral excess area 60 surrounding the effective area 58. For convenience, a ring-shaped boundary 62 between the effective area 58 and the peripheral excess area 60 is shown by a two-dot chain line in FIG. 6(a), but in reality, no line indicating the boundary 62 exists. A curved chamfer 64 is formed on the outer periphery of the wafer 52, and a notch 66 indicating the crystal orientation is formed. When a single wafer 52 is processed, a circular protective tape 68 is attached to the surface 52 a of the wafer 52 .

[0027] (Bonded wafer 70) The wafer processing apparatus 2 can process not only a single wafer 52, but also a bonded wafer 70 shown in Figures 7(a) and 7(b). The bonded wafer 70 is formed by stacking and integrating a first wafer 52' ​​and a second wafer 52" together. The configuration of the first and second wafers 52', 52" (for example, the devices 54 and the planned dividing lines 56) may be the same as the configuration of the single wafer 52 described above, and therefore the same reference numerals are used and a description thereof will be omitted.

[0028] When forming the bonded wafer 70, the effective region 58 of the first wafer 52' ​​and the effective region 58 of the second wafer 52" are bonded together. At this time, the notch 66 of the first wafer 52' ​​and the notch 66 of the second wafer 52" are aligned, and the first and second wafers 52', 52" are bonded together with the crystal orientations of the first and second wafers 52', 52" aligned. After the first and second wafers 52', 52" are bonded together, they are preferably heat-treated to bond the first and second wafers 52', 52" together by siloxane bonding.

[0029] Before processing using the above-mentioned wafer processing device 2, the focal point of a laser beam having a wavelength that is transparent to the wafer is positioned inside the peripheral excess region 60, and the laser beam is irradiated onto the wafer to form a modified layer along the chamfered portion 64.

[0030] (Formation of modified layer) The modified layer can be formed, for example, by using a laser processing device 72 shown in Figures 8 and 9. The laser processing device 72 includes a chuck table 74 that holds the wafer by suction, an oscillator (not shown) that oscillates a pulsed laser beam LB having a wavelength that is transparent to the wafer, and a condenser 76 (see Figure 9) that condenses the laser beam LB oscillated by the oscillator and irradiates the wafer with it.

[0031] As shown in Fig. 8, a circular suction chuck 78 is disposed on the upper end of the chuck table 74. The suction chuck 78 is formed from a porous material such as porous ceramics, and is connected to a suction means (not shown). The chuck table 74 is rotated by a motor (not shown) in the direction indicated by arrow R2 in Fig. 9.

[0032] The following mainly describes an example in which processing is performed on the first wafer 52' ​​of the bonded wafer 70. To form a modified layer, first, the bonded wafer 70 is suction-held on the upper surface of the chuck table 74. At this time, the bonded wafer 70 is placed on the upper surface of the chuck table 74 with the center of rotation of the chuck table 74 aligned with the center of the bonded wafer 70. At this time, the first wafer 52' ​​from which the chamfered portion 64 is to be removed is positioned on top. Then, a suction force is generated on the upper surface of the suction chuck 78 by the suction means, and the second wafer 52'' side of the bonded wafer 70 is suction-held on the upper surface of the suction chuck 78.

[0033] Once the bonded wafer 70 is suction-held on the chuck table 74, a processing line to be irradiated with the laser beam LB is set. To do this, the first wafer 52′ is imaged from above using an imaging means (not shown) of the laser processing device 72, and the outer periphery and center position of the first wafer 52′ are detected based on the image of the first wafer 52′ captured by the imaging means. Next, based on the detected outer periphery and center position of the first wafer 52′, a ring-shaped line located within the outer periphery excess region 60 and radially inward of the chamfered portion 64 of the first wafer 52′ is set as the processing line. For example, if the chamfered portion 64 is formed in a ring-shaped region 0.5 mm wide from the outer periphery of the first wafer 52′, a ring-shaped line located 3 mm radially inward from the outer periphery of the first wafer 52′ is set as the processing line.

[0034] After the line to be processed along which the laser beam LB is to be irradiated has been set, the focal point of the laser beam LB is positioned at a required position on the line to be processed. At this time, the height of the back surface 52b' of the first wafer 52' ​​is detected by a height detection means (not shown) of the laser processing device 72. Then, using the detected height of the back surface 52b' as a reference, the focal point of the laser beam LB is positioned at a required position on the line to be processed within the first wafer 52' ​​(inside the outer peripheral excess region 60).

[0035] Once the focal point of the laser beam LB has been positioned at the required position, the first wafer 52' ​​is irradiated with the laser beam LB having a wavelength that is transparent to the first wafer 52' ​​to form a ring-shaped modified layer along the chamfered portion 64. That is, by irradiating the first wafer 52' ​​with the laser beam LB while rotating the chuck table 74 in the direction indicated by arrow R2 in Figure 9, a ring-shaped modified layer 80 is formed along the entire circumference of the ring-shaped intended processing line.

[0036] After one ring-shaped modified layer 80 (one circumference) has been formed, the height position of the focal point of the laser beam LB is shifted to a shallower position, and the laser beam LB is irradiated onto the first wafer 52' ​​in the same manner as described above. By repeating this process of shifting the height position of the focal point and irradiating the laser beam LB, multiple ring-shaped modified layers 80 are formed at intervals in the vertical direction, as shown in Figure 10(a) (Type 1).

[0037] Furthermore, as shown in Figure 10(b), by repeatedly changing the height position and radial position of the focal point of the laser beam LB and irradiating the laser beam LB, multiple ring-shaped modified layers 80 may be formed at intervals in the vertical and radial directions (Type 2).

[0038] Alternatively, as shown in Figure 10(c), multiple ring-shaped modified layers 80 may be formed at intervals in the vertical direction, and multiple ring-shaped modified layers 80 may be formed at intervals in the radial direction on the surface 52a' side (bonding surface side) of the first wafer 52' ​​(Type 3).

[0039] Alternatively, as shown in Figure 10(d), multiple ring-shaped modified layers 80 may be formed at intervals in the vertical direction, and multiple ring-shaped modified layers 80 may be formed at intervals in the radial direction on the back surface 52b' side (exposed surface side) of the first wafer 52' ​​(Type 4).

[0040] In any of the above types 1 to 4, after forming the ring-shaped modified layer 80 along the chamfered portion 64, modified layers 82 may be further formed radially from the ring-shaped modified layer 80, as shown in Fig. 11. That is, a plurality of linear modified layers 82 (three in the illustrated embodiment) extending radially from the ring-shaped modified layer 80 to the outer circumferential edge of the first wafer 52' ​​may be formed at equal intervals in the circumferential direction inside the first wafer 52'. By forming such radial modified layers 82, when removing the chamfered portion 64 using the wafer processing device 2, the chamfered portion 64 can be divided into small pieces and removed well.

[0041] The formation of such modified layers 80, 82 can be carried out, for example, under the following processing conditions: Note that the defocus described below is the amount of movement of the condenser 76 when the condenser 76 is moved toward the bonded wafer 70 from a state in which the focal point of the laser beam LB is positioned on the back surface 52b' (exposed surface) of the first wafer 52'. Laser beam wavelength: 1099nm Repetition frequency: 80kHz Average output: 2W Defocus: 180μm, 170μm, 160μm, 150μm Feed speed: 450mm / s

[0042] The modified layers 80, 82 can also be formed in the same manner as above on the single wafer 52 shown in Fig. 6. However, when forming the modified layers 80, 82 on the single wafer 52, the back surface 52b of the single wafer 52 is faced upward, and the protective tape 68 side is held by suction on the chuck table 74 of the laser processing device 72.

[0043] (Removal of chamfered portion 64) After the modified layer 80 is formed along the chamfered portion 64, the chamfered portion 64 is removed from the first wafer 52' ​​using the wafer processing device 2 described above.

[0044] When removing the chamfered portion 64 using the wafer processing apparatus 2, first, the holding table 4 is positioned at the upper attachment / detachment position shown in FIG. 12. Next, the bonded wafer 70 is placed on the upper surface of the holding table 4 with the first wafer 52′ on which the modified layer 80 has been formed facing upward. Next, a suction force is generated on the upper surface of the suction chuck 10 by the suction means, and the second wafer 52″ side of the bonded wafer 70 is suction-held on the upper surface of the suction chuck 10. Next, the holding table 4 is lowered to the lower removal position shown in FIG. 13. Then, the holding table 4 is rotated in the direction indicated by arrow R3 in FIG. 13. This allows centrifugal force to be generated on the chamfered portion 64 of the first wafer 52′.

[0045] In the wafer processing apparatus 2, when the rotational speed of the holding table 4 reaches a predetermined value (e.g., 3000 rpm), the external force applying means 8 applies an external force to the chamfered portion 64. For example, in the external force applying means 8 shown in FIG. 2, when the rotational speed of the holding table 4 reaches the predetermined value, the external force applying means 8 swings to the position indicated by the two-dot chain line in FIG. 2, and the claws 22a of the action point 22 apply a force to the chamfered portion 64 of the first wafer 52'. This causes the chamfered portion 64 to separate from the first wafer 52' ​​starting from the modified layer 80, and the chamfered portion 64 is scattered by centrifugal force. In this way, the chamfered portion 64 can be removed from the first wafer 52' ​​(see FIG. 14).

[0046] In the external force application means 8 shown in FIG. 3, when the rotational speed of the holding table 4 reaches a predetermined value, the weight of the force point 18 moves to the outer periphery (radially outward of the holding table 4) overcoming the resistance of the spring 28. This causes the external force application means 8 to swing in the direction indicated by the arrow R1 toward the position indicated by the two-dot chain line in FIG. 3, and the claw 22a of the action point 22 applies a force to the chamfered portion 64. As a result, the chamfered portion 64 separates from the first wafer 52′ starting from the modified layer 80, and is scattered by centrifugal force. In this way, the chamfered portion 64 can be removed from the first wafer 52′.

[0047] In the external force application means 8 shown in FIG. 4, when the rotational speed of the holding table 4 reaches a predetermined value, the weight of the force point 18 moves to the outer periphery (the radially outer side of the holding table 4) by overcoming the resistance of the magnet 30 (the attractive force of the first magnet 30a and the second magnet 30b). This causes the external force application means 8 to swing in the direction indicated by the arrow R1 toward the position indicated by the two-dot chain line in FIG. 4, and the claw 22a of the action point 22 applies a stimulus to the chamfered portion 64. As a result, the chamfered portion 64 separates from the first wafer 52′ starting from the modified layer 80, and the chamfered portion 64 is scattered by centrifugal force. In this way, the chamfered portion 64 can be removed from the first wafer 52′. The external force application means 8 shown in FIG. 4 starts swinging when the rotational speed exceeds a predetermined value, which is advantageous because it can apply a stronger stimulus to the chamfered portion 64 than the embodiments shown in FIGS. 2 and 3.

[0048] Furthermore, in the external force applying means 8 shown in FIG. 5, when the rotational speed of the holding table 4 reaches a predetermined value, the controller 40 opens the valve 38 to supply fluid F from the fluid supply source 34 to the nozzle 32. This causes fluid F to be sprayed from the nozzle 32 onto the chamfered portion 64, stimulating the chamfered portion 64. As a result, the chamfered portion 64 separates from the first wafer 52′ starting from the modified layer 80, and the chamfered portion 64 is scattered by centrifugal force. In this manner, the chamfered portion 64 can be removed from the first wafer 52′. Note that, in the external force applying means 8 shown in FIG. 5, the fluid F is sprayed onto the chamfered portion 64 from directly above the chamfered portion 64; however, the fluid F may also be sprayed onto the chamfered portion 64 from diagonally above or to the side of the chamfered portion 64.

[0049] As described above, in the wafer processing apparatus 2 of this embodiment, the external force applying means 8 applies a stimulus to the chamfered portion 64, and the chamfered portion 64 is scattered and removed by centrifugal force, so that the chamfered portion 64 can be completely removed from the wafer 52 on which the ring-shaped modified layer 80 is formed. This eliminates problems such as the remaining portion falling off in a later process and becoming a source of contamination, or causing chipping of device chips when the wafer 52 is divided into individual device chips. [Explanation of symbols]

[0050] 2: Wafer processing equipment 4: Holding table 6: Rotation means 8: External force application means 18: Emphasis 20:Fulcrum 22: Point of action 22a: Nail 28: Spring 30: Magnet 30a: First magnet 30b: Second magnet 32: Nozzle 52: Wafer 52a: Surface of wafer 52b: Backside of wafer 52': First wafer 52a': Surface of first wafer 52b': Backside of the first wafer 52": Second wafer 52a″: surface of second wafer 52b": Backside of second wafer 54: Device 56: Planned division line 58: Effective area 60: Surplus outer area 64: Chamfered part 80: Ring-shaped modified layer LB: Laser beam F:Fluid

Claims

1. A wafer processing device for removing a chamfered portion from a wafer having a modified layer formed along the chamfered portion by positioning a focal point of a laser beam having a wavelength that is transparent to the wafer within the peripheral excess region, the laser beam having a wavelength that is transparent to the wafer, the focal point of the laser beam being located within the peripheral excess region, the wafer having a useful area including a device region in which a plurality of devices are partitioned by planned division lines and a chamfered portion that surrounds the useful area, the wafer being processed according to the present invention. a holding table for holding a wafer; a rotating means for rotating the holding table to generate centrifugal force on the chamfered portion; an external force applying means for applying an external force to the chamfered portion when the rotation speed of the holding table reaches a predetermined value; The wafer processing device applies a stimulus to the chamfered portion by the external force applying means, and scatters and removes the chamfered portion by centrifugal force.

2. The external force applying means is a lever having a force point, a fulcrum, and a point of action, the fulcrum being formed on the outer periphery of the holding table, the force point being formed by a weight, and a claw being formed at the point of action to apply a stimulus to the chamfered portion, 2. The wafer processing device according to claim 1, wherein when the centrifugal force generated by the rotation of the holding table moves the weight to the outer periphery and the rotation speed reaches a predetermined value, the claws at the action points apply an impulse to the chamfered portion, causing the chamfered portion to be scattered and removed by the centrifugal force.

3. 3. The wafer processing device according to claim 2, wherein the weight is provided with a spring that resists centrifugal force, and when the rotational speed of the holding table reaches a predetermined value, the weight overcomes the resistance of the spring and moves to the outer periphery, causing the claws at the points of action to apply a stimulus to the chamfered portion, thereby scattering and removing the chamfered portion by centrifugal force.

4. 3. The wafer processing device according to claim 2, wherein a magnet that resists centrifugal force is disposed on the weight, and when the rotational speed of the holding table reaches a predetermined value, the weight overcomes the resistance of the magnet and moves to the outer periphery, causing the claws at the action points to apply a stimulus to the chamfered portion, thereby scattering and removing the chamfered portion by centrifugal force.

5. 2. The wafer processing device according to claim 1, wherein the external force applying means includes a nozzle for spraying a fluid onto the chamfered portion, and when the rotational speed of the holding table reaches a predetermined value, the fluid sprayed from the nozzle stimulates the chamfered portion, scattering and removing the chamfered portion by centrifugal force.

6. 2. The wafer processing apparatus according to claim 1, wherein the predetermined rotational speed of said holding table is 3000 rpm.

Images