Wafer processing method

Abstract

The present invention provides a wafer processing method that can effectively remove grinding debris adhering to the inside of a ring-shaped reinforcement. [Solution] The wafer processing method includes a grinding step of grinding the back surface 66b of the wafer 66 with a grinding means 6b that rotatably mounts a grinding wheel 32b on which grinding wheels 34b having a diameter equal to the radius of the wafer 66 are arranged in an annular shape. In the grinding step, the wafer 66 is rotated by the rotation of the chuck table 12, and the grinding wheels 34b of the grinding wheel 32b are positioned inside the area corresponding to the excess area on the outer circumference of the wafer 66 and are positioned to pass through the rotation center of the wafer 66, thereby grinding and thinning the back surface 66b corresponding to the device area to form a ring-shaped reinforcement portion 80 on the outer circumference. After that, the grinding wheels 34b are separated from the back surface 66b of the wafer 66, and a conical grinding water W sprayed from a spray nozzle 42 is applied to the inside of the ring-shaped reinforcement portion 80 for cleaning.

Description

Technical Field

[0001] The present invention relates to a method for processing a wafer by grinding the back surface of a wafer on which a device region partitioned by a planned division line and an outer peripheral surplus region surrounding the device region are formed on the surface.

Background Art

[0002] A wafer on which a device region partitioned by a planned division line and an outer peripheral surplus region surrounding the device region are formed on the surface for a plurality of devices such as ICs and LSIs is thinned by grinding the back surface and then divided into individual device chips by a dicing device, a laser processing device, etc. Each of the divided device chips is used in electrical devices such as mobile phones and personal computers.

[0003] In addition, since it becomes difficult to transport the wafer to the next process after grinding and thinning the back surface of the wafer, the applicant has proposed a technique of grinding and thinning the back surface corresponding to the device region and forming a ring-shaped reinforcing portion on the back surface corresponding to the outer peripheral surplus region (for example, see Patent Document 1). And since processing such as insulation film, wiring, and chip lamination is performed on the back surface corresponding to the device region in the next process, the back surface of the wafer after grinding is washed by washing means so that foreign matter does not remain on the back surface corresponding to the device region.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, there is a problem that grinding debris adheres to the inside of the ring-shaped reinforcing portion and cannot be sufficiently removed by the cleaning means, causing an obstacle to the processing performed in the next process.

[0006] The object of the present invention is to provide a wafer processing method that can sufficiently remove grinding debris adhering to the inside of the ring-shaped reinforcement portion. [Means for solving the problem]

[0007] According to the present invention, the following wafer processing method is provided that solves the above problems. That is, A wafer processing method for grinding the back surface of a wafer in which a device region partitioned by dividing lines and an outer peripheral excess region surrounding the device region are formed on the surface, A protective member placement step in which a protective member is placed on the surface of the wafer, A holding step in which the back surface of the wafer is exposed and the protective member side is held on a rotatable chuck table, The process includes grinding the back surface of a wafer using a grinding means that rotatably mounts a grinding wheel on which grinding wheels, whose diameter is the radius of the wafer, are arranged in an annular pattern, and the back surface of the wafer is ground using this means. The grinding means comprises a rotating shaft having a central introduction passage for rotating the grinding wheel and introducing grinding fluid, an injection nozzle for spraying the grinding fluid introduced into the introduction passage in a conical shape from the inside of the grinding wheel to the contact area between the grinding wheel and the wafer, and a feed unit for grinding and feeding the grinding wheel relative to the wafer and then moving it away. In the grinding process, the wafer is rotated by the rotation of the chuck table, and the annular grinding wheel disposed on the grinding wheel is positioned inside the area corresponding to the excess area on the outer circumference of the wafer and is positioned to pass through the center of rotation of the wafer, thereby grinding and thinning the back surface corresponding to the device area to form a ring-shaped reinforcing portion on the outer circumference. The present invention provides a wafer processing method comprising a cleaning step in which the feed unit is operated to separate the grinding wheel from the back surface of the wafer, and conical grinding water sprayed from the spray nozzle is directed onto the inside of the ring-shaped reinforcing portion for cleaning.

[0008] Preferably, the grinding means comprises a first grinding means equipped with a rough grinding wheel for rough grinding and a second grinding means equipped with a finishing grinding wheel for finishing grinding, and the cleaning process is carried out by at least the second grinding means. It is desirable to carry out the cleaning process by the first grinding means. In the cleaning process, it is preferable to rotate the rotating shaft of the grinding means to accelerate the conical grinding water sprayed from the spray nozzle by centrifugal force. [Effects of the Invention]

[0009] The wafer processing method of the present invention is A wafer processing method for grinding the back surface of a wafer in which a device region partitioned by dividing lines and an outer peripheral excess region surrounding the device region are formed on the surface, A protective member placement step in which a protective member is placed on the surface of the wafer, A holding step in which the back surface of the wafer is exposed and the protective member side is held on a rotatable chuck table, The process includes grinding the back surface of a wafer using a grinding means that rotatably mounts a grinding wheel on which grinding wheels, whose diameter is the radius of the wafer, are arranged in an annular pattern, and the back surface of the wafer is ground using this means. The grinding means comprises a rotating shaft having a central introduction passage for rotating the grinding wheel and introducing grinding fluid, an injection nozzle for spraying the grinding fluid introduced into the introduction passage in a conical shape from the inside of the grinding wheel to the contact area between the grinding wheel and the wafer, and a feed unit for grinding and feeding the grinding wheel relative to the wafer and then moving it away. In the grinding process, the wafer is rotated by the rotation of the chuck table, and the annular grinding wheel disposed on the grinding wheel is positioned inside the area corresponding to the excess area on the outer circumference of the wafer and is positioned to pass through the center of rotation of the wafer, thereby grinding and thinning the back surface corresponding to the device area to form a ring-shaped reinforcing portion on the outer circumference. Thereafter, since there is a cleaning step of operating the feeding unit to separate the grinding wheel from the back surface of the wafer and applying the conical grinding water jetted from the injection nozzle to the inside of the ring-shaped reinforcing portion for cleaning, it is possible to sufficiently remove the grinding chips adhering to the inside of the ring-shaped reinforcing portion. Therefore, the problem of hindrance to the processing carried out in the next step is solved.

Brief Description of the Drawings

[0010] [Figure 1] Perspective view of the grinding device. [Figure 2] Partial cross-sectional view of the grinding means shown in FIG. 1. [Figure 3] Enlarged cross-sectional view of the injection nozzle shown in FIG. 2. [Figure 4] Schematic diagram showing the protective member arrangement step. [Figure 5] Schematic diagram showing the holding step. [Figure 6] (a) Schematic diagram showing rough grinding in the grinding step, (b) Cross-sectional schematic diagram of the wafer after rough grinding. [Figure 7] (a) Schematic diagram showing finish grinding in the grinding step, (b) Cross-sectional schematic diagram of the wafer after finish grinding. [Figure 8] Schematic diagram showing the cleaning step. [Figure 9] (a) Schematic diagram showing a state where grinding chips adhere to the inside of the ring-shaped reinforcing portion, (b) Schematic diagram showing a state where the cleaning step is carried out and the grinding chips are removed from the inside of the ring-shaped reinforcing portion.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, a preferred embodiment of the wafer processing method according to the present invention will be described with reference to the drawings.

[0012] (Grinding device 2) FIG. 1 shows a grinding device 2 that can be used when implementing the wafer processing method according to the present invention. The grinding device 2 includes a holding means 4 for holding a wafer and a grinding means 6 for grinding the wafer held by the holding means 4.

[0013] (Holding means 4 of grinding device 2) The holding means 4 includes a circular turntable 10 rotatably supported on the base 8 of the grinding device 2, and three chuck tables 12 mounted on the upper surface of the turntable 10 at equal intervals in the circumferential direction. When the turntable 10 rotates, the three chuck tables 12 are sequentially positioned at the attachment / detachment position A, the rough grinding position B, and the finish grinding position C.

[0014] The chuck table 12 sucks and holds the wafer and is configured to be rotatable. A circular suction chuck 14 is arranged at the upper end of the chuck table 12. The suction chuck 14 is formed of a porous member such as porous ceramics. Further, the suction chuck 14 is connected to a suction means (not shown). In the chuck table 12, by generating a suction force on the upper surface of the suction chuck 14 by the suction means, the wafer placed on the upper surface of the suction chuck 14 is sucked and held. Furthermore, the chuck table 12 is rotated by a chuck table motor (not shown) with an axis extending in the vertical direction through the center in the radial direction of the chuck table 12 as the rotation center.

[0015] (Grinding means 6 of grinding device 2) The grinding means 6 of the present embodiment includes a first grinding means 6a equipped with a rough grinding wheel for performing rough grinding and a second grinding means 6b equipped with a finish grinding wheel for performing finish grinding. However, the grinding means 6 is not limited to the form including the first and second grinding means 6a and 6b as in the present embodiment, and may be single.

[0016] (First grinding means 6a) The first grinding means 6a performs rough grinding on a wafer positioned at the rough grinding position B. The first grinding means 6a includes a lifting plate 18 that is vertically movable and supported on a support wall 16 extending upward from the end of the base 8 (the far end in Figure 1), a protruding member 20 that protrudes from the lifting plate 18, a housing 22 mounted on the protruding member 20, a rotating shaft 24 that is rotatable about an axis extending in the vertical direction and supported by the housing 22, and a rotating shaft motor 26 that rotates the rotating shaft 24. As shown in Figure 2, a disc-shaped wheel mount 28 is provided at the lower part of the rotating shaft 24. An annular rough grinding wheel 32a is fastened to the wheel mount 28 by bolts 30. A rough grinding wheel 34a is arranged annularly on the lower surface of the grinding wheel 32a. The diameter of the grinding wheel 34a is approximately the same as the radius of the wafer to be ground. The abrasive grains of the grinding wheel 34a can be, for example, diamond abrasive grains with a particle size of about 5 μm to 20 μm.

[0017] The description of the first grinding means 6a will continue with reference to Figures 1 to 3. As shown in Figure 1, the rotating shaft 24 passes through the rotating shaft motor 26. The rotating shaft 24 is hollow, and an introduction passage 24a for introducing grinding water W (for example, pure water) is provided in the center of the rotating shaft 24. The introduction passage 24a of the rotating shaft 24 is connected to the grinding water source 38 via a flow path 36 such as a hose. An on / off valve 40 is provided in the flow path 36. As shown in Figures 2 and 3, a spray nozzle 42 is attached to the lower end of the rotating shaft 24. The spray nozzle 42 has a cylindrical hanging portion 42a that hangs down from the lower end of the rotating shaft 24, an inverted truncated cone-shaped inclined portion 42b whose diameter gradually decreases downward from the lower end of the hanging portion 42a, and a circular bottom portion 42c that closes the lower end of the inclined portion 42b. Multiple spray holes 42d are formed in the inclined portion 42b of the spray nozzle 42 at intervals in the circumferential direction. The grinding water W introduced from the grinding water source 38 into the introduction passage 24a of the rotating shaft 24 is then sprayed in a conical (radial) shape from multiple injection ports 42d of the injection nozzle 42. In other words, the injection nozzle 42 sprays the grinding water W introduced into the introduction passage 24a in a conical shape from the inside of the rough grinding wheel 32a to the contact area between the grinding wheel 34a and the wafer.

[0018] The first grinding means 6a further includes a feed unit 44 that feeds the grinding wheel 34a to the wafer and moves it away from it (see Figure 1). The feed unit 44 has a ball screw 46 that extends vertically along the support wall 16 and a motor 48 that rotates the ball screw 46. The nut portion of the ball screw 46 (not shown) is connected to the lifting plate 18. The feed unit 44 converts the rotational motion of the motor 48 into linear motion using the ball screw 46 and transmits it to the lifting plate 18, causing the lifting plate 18 to move up and down along the guide rail 16a attached to the support wall 16. As a result, the grinding wheel 34a is fed (descended) and moved away (raised) from the wafer.

[0019] Thus, the first grinding means 6a is rotatably mounted on a grinding wheel 32a on which grinding wheels 34a, whose diameter is the radius of the wafer, are arranged in an annular shape. Furthermore, the first grinding means 6a includes a rotating shaft 24 with an introduction passage 24a in the center for rotating the grinding wheel 32a and introducing grinding water W, an injection nozzle 42 for spraying the grinding water W introduced into the introduction passage 24a in a conical shape from the inside of the grinding wheel 32a to the contact point between the grinding wheel 34a and the wafer, and a feed unit 44 for grinding and feeding the grinding wheel 34a relative to the wafer and moving it away from it.

[0020] (Second grinding means 6b) The second grinding means 6b performs finish grinding on the wafer positioned at the finishing position C. That is, the second grinding means 6b is equipped with a finishing grinding wheel 32b for performing finish grinding (see Figure 2). The finishing grinding wheel 34b, which is arranged in an annular shape on the lower surface of the grinding wheel 32b, is made up of abrasive grains with a smaller particle size than the abrasive grains of the grinding wheel 34a (rough grinding wheel) of the first grinding means 6a. The abrasive grains of the finishing grinding wheel 34b may be, for example, diamond abrasive grains with a particle size of about 0.5 μm to 2 μm. The second grinding means 6b may have the same configuration as the first grinding means 6a, except for the finishing grinding wheel 32b and the grinding wheel 34b, so the same reference numerals as the first grinding means 6a are used and the explanation is omitted.

[0021] The description of the grinding apparatus 2 will continue with reference to Figure 1. In this embodiment, the grinding apparatus 2 has a cassette storage area 52 on the upper surface of the base 8 where a cassette 50 capable of accommodating multiple wafers is placed. The cassette storage area 52 has a first cassette storage area 52a where a first cassette 50a containing wafers before grinding is placed, and a second cassette storage area 52b where a second cassette 50b containing wafers after grinding is placed.

[0022] Furthermore, the grinding apparatus 2 of this embodiment includes an unloading / unloading means 54 for unloading wafers from a first cassette 50a and loading grinding wafers into a second cassette 50b, a centering table 56 for aligning the center of the unloading wafer unloaded by the unloading / unloading means 54 to a predetermined position, a first transport means 58 for transporting the wafer, whose center has been aligned to a predetermined position, to the chuck table 12 at the attachment / detachment position A, a cleaning water nozzle 60 for spraying cleaning water toward the upper surface (grinding surface) of the wafer positioned at the attachment / detachment position A after rough grinding and finish grinding have been performed, a spinner cleaning means 62 for spinner cleaning the grinding wafer, and a second transport means 64 for transporting the grinding wafer from the chuck table 12 at the attachment / detachment position A to the spinner cleaning means 62.

[0023] (Waha 66) Figure 4 shows a disc-shaped wafer 66 that can be processed according to the present invention. The wafer 66 can be formed from a suitable semiconductor material such as silicon. The dimensions of the wafer 66 are, for example, a diameter of 200 mm and a thickness of approximately 700 μm. On the surface 66a of the wafer 66, a device region 72 is formed, in which multiple devices 68 such as ICs and LSIs are demarcated by grid-like division lines 70, and an outer peripheral surplus region 74 surrounds the device region 72. In Figure 4, the ring-shaped boundary 76 between the device region 72 and the outer peripheral surplus region 74 is shown by a dashed line for convenience, but in reality, there is no line indicating the boundary 76.

[0024] Next, an example of carrying out the wafer processing method according to the present invention using the grinding apparatus 2 described above will be explained.

[0025] (Protective member installation process) In this embodiment, first, as shown in Figure 4, a protective member placement step is performed in which a protective member 78 is placed on the surface 66a of the wafer 66. The protective member 78 may be a circular adhesive tape or thermocompression sheet having a diameter approximately the same as the diameter of the wafer 66. The thermocompression sheet is a sheet of thermoplastic synthetic resin (for example, polyolefin resin) that softens or melts and exhibits adhesive force when heated to a temperature near its melting point.

[0026] After the protective member placement process is carried out, the multiple wafers 66 with the protective members 78 placed on them are placed in the first cassette 50a, and the first cassette 50a is placed in the first cassette storage area 52a of the grinding device 2. In this way, the multiple wafers 66 to be ground are set in the grinding device 2. In addition, an empty second cassette 50b for storing the ground wafers 66 is placed in the second cassette storage area 52b.

[0027] (holding process) After setting the wafer 66 to be ground in the grinding device 2, when an instruction to start processing is input to the grinding device 2, the grinding device 2 performs a holding process in which the back surface 66b of the wafer 66 is exposed and the side with the protective member 78 is held in place by the rotatable chuck table 12.

[0028] In the holding process of this embodiment, first, the wafer 66 before grinding is unloaded from the first cassette 50a to the centering table 56 by the loading / unloading means 54. Next, the center of the wafer 66 is aligned to a predetermined position on the centering table 56. Then, the wafer 66 is transported from the centering table 56 to the chuck table 12 positioned at the attachment / detachment position A by the first transport means 58, and the wafer 66 is placed on the upper surface of the chuck table 12 with its back surface 66b facing upwards (see Figure 5). As described above, since the center of the wafer 66 is aligned to a predetermined position on the centering table 56 before being transported by the first transport means 58, when the wafer 66 is placed on the chuck table 12, the center of the wafer 66 and the rotation center of the chuck table 12 are aligned. Then, a suction force is generated in the suction chuck 14 of the chuck table 12, and the wafer 66 is held in place by the chuck table 12.

[0029] (Grinding process) After the holding process is performed, a grinding process is carried out in which the back surface 66b of the wafer 66 is ground using a grinding means that is rotatably mounted on a grinding wheel in which grinding wheels, whose diameter is the radius of the wafer 66, are arranged in an annular shape. In the grinding process of this embodiment, rough grinding is first performed by the first grinding means 6a, and then finish grinding is performed by the second grinding means 6b.

[0030] (Rough grinding by the first grinding means 6a) In rough grinding, first, the turntable 10 is rotated to position the chuck table 12, which holds the wafer 66 by suction, at the rough grinding position B. At the rough grinding position B, the grinding wheel 34a of the rough grinding wheel 32a is positioned inside the area corresponding to the excess area 74 on the outer circumference of the wafer 66 and passes through the center of rotation of the wafer 66. Next, the rotation axis 24 is rotated in the direction indicated by arrow R1 in Figure 6(a). The chuck table 12 is also rotated in the direction indicated by arrow R2. Next, the grinding wheel 32a is lowered, and the grinding wheel 34a for rough grinding is brought into contact with the back surface 66b of the wafer 66. Grinding water W is also sprayed in a conical shape from the spray nozzle 42 from the inside of the grinding wheel 32a to the contact area between the grinding wheel 34a and the wafer 66. Then, the grinding wheel 32a is fed at a predetermined feed rate. As a result, as shown in Figure 6(b), the back surface 66b of the wafer 66 corresponding to the device region 72 is ground down to thin it, and a ring-shaped reinforcing portion 80 can be formed on the back surface 66b of the wafer 66 corresponding to the outer peripheral excess region 74. Note that in Figure 6(b) and other figures, the shape of the wafer 66 is exaggerated for convenience.

[0031] (Processing conditions for rough grinding) Rough grinding can be performed under the following processing conditions, for example. Grinding wheel feed rate: 1.0 μm / s Grinding water injection volume: 5 L / min Grinding wheel rotation speed: 3000 rpm Chuck table rotation speed: 300 rpm Thickness to be ground (removed) from the wafer: 600 μm

[0032] (Finish grinding by the second grinding means 6b) After rough grinding, the turntable 10 is rotated to position the chuck table 12, which is holding the roughly ground wafer 66 by suction, at the finishing position C. At the finishing position C, the grinding wheel 34b of the finishing grinding wheel 32b is positioned inside the area corresponding to the excess area 74 on the outer circumference of the wafer 66 and passes through the center of rotation of the wafer 66. Next, the rotation axis 24 is rotated in the direction indicated by arrow R1 in Figure 7(a). The chuck table 12 is also rotated in the direction indicated by arrow R2. Next, the grinding wheel 32b is lowered, and the finishing grinding wheel 34b is brought into contact with the back surface 66b of the wafer 66. Grinding water W is also sprayed in a conical shape from the spray nozzle 42 from the inside of the grinding wheel 32b to the contact area between the grinding wheel 34b and the wafer 66. Then, the grinding wheel 32b is fed at a predetermined feed rate. As a result, as shown in Figure 7(b), the back surface 66b of the wafer 66 corresponding to the device region 72 can be finished grinding.

[0033] (Processing conditions for finish grinding) Finish grinding can be performed under the following processing conditions, for example. Grinding wheel feed rate: 0.1 μm / s Grinding water injection volume: 5 L / min Grinding wheel rotation speed: 3000 rpm Chuck table rotation speed: 300 rpm Thickness to be removed from the wafer: 60 μm

[0034] (Washing process) After the finish grinding of the grinding process, as shown in Figure 8, the feed unit 44 is activated to separate the grinding wheel 34b from the back surface 66b of the wafer 66, and a cleaning process is carried out by the second grinding means 6b, in which the conical grinding water W sprayed from the spray nozzle 42 is directed onto the inside of the ring-shaped reinforcing part 80 for cleaning.

[0035] In the cleaning process, first, the grinding wheel 32b is raised by the feed unit 44, separating the grinding wheel 34b from the back surface 66b of the wafer 66. Specifically, the grinding wheel 32b is positioned so that the grinding water W from the spray nozzle 42 directly hits the inside of the ring-shaped reinforcement part 80. Next, the chuck table 12 is rotated at a predetermined rotational speed (for example, 300 rpm) in the direction indicated by arrow R2 in Figure 8. Then, the grinding water W is sprayed from the spray nozzle 42 in a conical shape. Since the grinding water W sprayed from the spray nozzle 42 directly hits the inside of the ring-shaped reinforcement part 80 to which the grinding debris 82 is attached, the grinding debris 82 can be effectively removed by the grinding water W (see Figures 9(a) and 9(b)). The cleaning time in the cleaning process can be about 10 seconds.

[0036] In the cleaning process, it is preferable to rotate the rotating shaft 24 of the second grinding means 6b in the direction indicated by arrow R1 in Figure 8, for example, to accelerate the conical grinding water W sprayed from the spray nozzle 42 by centrifugal force. This makes it possible to remove grinding debris 82 adhering to the inside of the ring-shaped reinforcing portion 80 more effectively. From the viewpoint of improving the cleaning effect, it is preferable that the rotational speed of the rotating shaft 24 in the cleaning process be higher than the rotational speed of the rotating shaft 24 in the grinding process (for example, 6000 rpm). Furthermore, it is desirable that the amount of grinding water W sprayed in the cleaning process be greater than the amount of grinding water W sprayed in the grinding process (for example, 10 L / min).

[0037] The cleaning process may be performed not only by the second grinding means 6b after finish grinding, but also by the first grinding means 6a after rough grinding. By performing the above cleaning process after rough grinding as well, the amount of abrasive grains that have fallen off the grinding wheel 34a for rough grinding and remain on the wafer 66 during rough grinding can be reduced. This prevents the dragging of abrasive grains that have fallen off the grinding wheel 34a for rough grinding during finish grinding, and suppresses a deterioration in the quality of finish grinding. The conditions for the cleaning process performed after rough grinding may be the same as the conditions for the cleaning process performed after finish grinding.

[0038] After the cleaning process is completed, the turntable 10 is rotated to position the chuck table 12, which is holding the wafer 66 by suction, at the attachment / detachment position A. Next, cleaning water is sprayed from the cleaning water nozzle 60 toward the upper surface (grinding surface) of the wafer 66 to perform a basic cleaning of the upper surface of the wafer 66.

[0039] After briefly cleaning the top surface of the wafer 66, the wafer 66 is transported from the chuck table 12 at attachment / detachment position A to the spinner table 62a of the spinner cleaning means 62 by the second transport means 64. Next, the wafer 66 is held by suction on the spinner table 62a, and while rotating the spinner table 62a, cleaning water is sprayed from a cleaning water nozzle (not shown) to spinner clean the wafer 66. Next, while rotating the spinner table 62a, dry air is sprayed from an air nozzle (not shown) to remove the cleaning water from the wafer 66. Finally, the cleaned wafer 66 is loaded into the second cassette 50b by the loading / unloading means 54.

[0040] As described above, in the wafer processing method of this embodiment, in the grinding step, the wafer 66 is rotated by the rotation of the chuck table 12, and the annular grinding wheel 34b disposed on the grinding wheel 32b is positioned inside the area corresponding to the excess area 74 on the outer circumference of the wafer 66 and is positioned so as to pass through the rotation center of the wafer 66, thereby grinding and thinning the back surface 66b corresponding to the device area 72 to form a ring-shaped reinforcing portion 80 on the outer circumference. Subsequently, the feed unit 44 is operated to separate the grinding wheel 34b from the back surface 66b of the wafer 66, and a cleaning step is provided in which the conical grinding water W sprayed from the spray nozzle 42 is applied to the inside of the ring-shaped reinforcing portion 80 for cleaning. This makes it possible to sufficiently remove grinding debris 82 adhering to the inside of the ring-shaped reinforcing portion 80. Therefore, the problem of interference with processing carried out in the next step is resolved. [Explanation of Symbols]

[0041] 2: Grinding equipment 4: Holding means 6: Grinding method 6a: First grinding means 6b: Second grinding method 12: Chuck Table 24: Rotation axis 24a:Introduction path 32a: Grinding wheel for rough grinding 32b: Finishing grinding wheel 34a: Grinding wheel for rough grinding 34b: Finishing grinding wheel 42: Spray nozzle 44: Sending section 66: Waha 66a: Wafer surface 66b: Back side of the wafer 68: Device 70: Planned division line 72: Device Area 74: Perimeter surplus area 78: Protective component 80: Ring-shaped reinforcement 82: Grinding chips W: Grinding water

Claims

1. A wafer processing method for grinding the back surface of a wafer in which a device region partitioned by dividing lines and an outer peripheral excess region surrounding the device region are formed on the surface, A protective member placement step in which a protective member is placed on the surface of the wafer, A holding step in which the back surface of the wafer is exposed and the protective member side is held on a rotatable chuck table, The process includes grinding the back surface of a wafer using a grinding means that rotatably mounts a grinding wheel on which grinding wheels, whose diameter is the radius of the wafer, are arranged in an annular pattern, and the back surface of the wafer is ground using this means. The grinding means comprises a rotating shaft having a central introduction passage for rotating the grinding wheel and introducing grinding fluid, an injection nozzle for spraying the grinding fluid introduced into the introduction passage in a conical shape from the inside of the grinding wheel to the contact area between the grinding wheel and the wafer, and a feed unit for grinding and feeding the grinding wheel relative to the wafer and then moving it away. In the grinding process, the wafer is rotated by the rotation of the chuck table, and the annular grinding wheel disposed on the grinding wheel is positioned inside the area corresponding to the excess area on the outer circumference of the wafer and is positioned to pass through the center of rotation of the wafer, thereby grinding and thinning the back surface corresponding to the device area to form a ring-shaped reinforcing portion on the outer circumference. A wafer processing method comprising a cleaning step in which the feed unit is operated to separate the grinding wheel from the back surface of the wafer, and cone-shaped grinding water sprayed from the spray nozzle is directed onto the inside of the ring-shaped reinforcing part for cleaning.

2. The grinding means comprises a first grinding means equipped with a rough grinding wheel for rough grinding, and a second grinding means equipped with a finishing grinding wheel for finishing grinding, The wafer processing method according to claim 1, wherein the cleaning step is performed by at least the second grinding means.

3. The wafer processing method according to claim 2, wherein the cleaning step is carried out by the first grinding means.

4. The wafer processing method according to claim 1, wherein in the cleaning step, the rotating shaft of the grinding means is rotated to accelerate the conical grinding water sprayed from the spray nozzle by centrifugal force.

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