Wafer manufacturing method and chuck table

Abstract

To prevent a protective member from being brought into contact with a grindstone when the protective member is formed on a wafer, the protective member is sucked and held, and the wafer is ground and smoothed.SOLUTION: A method for manufacturing a wafer of uniform thickness by grinding, with a grindstone 166, a wafer having a protective member 81 for protecting the one surface and including a protrusion portion 814 annularly protruding outward from one surface of the wafer includes: a step of preparing, for a grinding device 1, a table 3 having a central suction surface 300 with the same shape as the other surface of the wafer, and an annular suction surface 320 annularly disposed outside the central suction surface 300 and sucking and holding the protrusion portion 814; a first grinding step of sucking and holding the protective member 81 by means of the central suction surface 300 and the annular suction surface 320 and grinding the other surface of the wafer by means of the grindstone 166; and a second grinding step of, after a step of peeling the protective member 81 from the wafer ground in the first grinding step, sucking and holding the other surface of the wafer by means of only the central suction surface 300 and grinding the one surface of the wafer by means of the grindstone 166.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a wafer manufacturing method for manufacturing wafers having a uniform thickness, and a chuck table used in the wafer manufacturing method. [Background technology]

[0002] For example, as disclosed in Patent Document 1 or Patent Document 2, in a wafer manufacturing method in which an ingot is sliced ​​to form as-sliced ​​wafers, and then both sides of the as-sliced ​​wafers having undulation or warpage are ground to manufacture wafers of uniform thickness, while one side of the as-sliced ​​wafer is ground, a liquid resin is spread and hardened on the other side to form a protective member for protecting the other side, and after one side is ground, the protective member is peeled off and the other side is ground. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-272557 A [Patent Document 2] JP 2020-205358 A [Patent Document 3] JP 2018-29131 A Summary of the Invention [Problem to be solved by the invention]

[0004] The protective member has an annular protruding portion that protrudes outward from the outer periphery of the wafer. The suction surface of the chuck table of the grinding device sucks and holds the protective member when one side of the wafer is ground. Because the suction surface does not suck and hold the protruding portion of the protective member, the flapping protective member may come into contact with the lower surface of the grinding wheel, causing a problem that the protective member adheres to the lower surface of the grinding wheel and reduces the grinding power of the grinding wheel.

[0005] Furthermore, when a protective member is formed on a wafer having an orientation flat formed by linearly cutting out the outer periphery, the protective member is formed in a circular shape as a whole, and the area adjacent to the orientation flat is exposed in a bow-shaped shape when viewed in a plane, making the bow-shaped area of ​​the protective member more likely to come into contact with a grinding wheel.

[0006] Therefore, in a wafer manufacturing method in which a protective member is formed on a wafer, the protective member is held by suction, and the wafer is ground to produce a flat wafer, there is a problem of preventing the protective member from coming into contact with the grinding wheel. [Means for solving the problem]

[0007] The present invention for solving the above-mentioned problems provides a method for manufacturing a wafer having a uniform thickness by grinding one surface and the other surface of a wafer, the one surface being provided with a protruding portion protruding in an annular shape on the outside of the one surface of the wafer and a protective member for protecting the one surface, the method comprising the steps of: (a) grinding the wafer with a grinding wheel; (b) grinding the wafer with a grinding wheel; a first grinding step of suction-holding the protective member with the central suction surface and the annular suction surface and grinding the other side of the wafer with the grinding wheel; a peeling step of peeling the protective member from the wafer ground in the first grinding step; and a second grinding step of, after the peeling step, suction-holding the other side of the wafer only with the central suction surface and grinding the one side of the wafer with the grinding wheel. For example, when the wafer has an orientation flat and the protective member has a circular outer shape, the chuck table prepared in the preparation process has a cutout portion corresponding to the orientation flat on the central suction surface and has a frame body surrounding the annular suction surface, the frame body having a frame cutout portion whose outer periphery is similar to the wafer, and in the wafer manufacturing method of the present invention, it is preferable that the preparation process includes a suction surface grinding process in which the central suction surface and the annular suction surface are ground with the grinding wheel.

[0008] In addition, to solve the above-mentioned problems, the present invention is a chuck table used in the manufacturing method of the wafer, comprising a central suction plate having the central suction surface, an annular suction plate having the annular suction surface, and a barrier separating the outer surface of the central suction plate from the inner surface of the annular suction plate, wherein the frame has a recess that accommodates the central suction plate, the barrier, and the annular suction plate and surrounds the outer periphery of the annular suction plate, and the central suction plate is a chuck table having the cutout portion corresponding to the orientation flat of the wafer. Effect of the Invention

[0009] The method for manufacturing a wafer according to the present invention performs a first grinding step in which the other side of the wafer is ground with a grinding wheel while the protective member is held by suction between the central suction surface and the annular suction surface of the chuck table to prevent flapping, and after the protective member is peeled off from the wafer ground in the first grinding step, the other side of the wafer is held by suction only with the central suction surface and one side of the wafer is ground with the grinding wheel, so that the protective member does not come into contact with the grinding wheel, and therefore the grinding power of the grinding wheel is not reduced. Furthermore, for example, when the wafer has an orientation flat and the protective member has a circular outer shape, the chuck table to be prepared has a notch portion corresponding to the orientation flat on the central suction surface, and a frame body surrounding the annular suction surface, and the frame body has an outer periphery similar to the wafer and has the frame body notch portion. In the wafer manufacturing method according to the present invention, the central suction surface and the annular suction surface are first ground (self-grinded) with a grinding wheel, and then, in the grinding wheel trajectory area passing through the orientation flat of the wafer held by suction on the self-grinding chuck table, the grinding pressure applied to the wafer is prevented from being higher than in other areas, and it is possible to make the wafer have a uniform thickness after grinding. [Brief description of the drawings]

[0010] [Figure 1]FIG. 2 is a perspective view showing an example of a grinding device. [Diagram 2] Fig. 2(A) is a perspective view showing an example of a wafer having a protective member that has a ring-shaped protruding portion on the outside of one surface to protect the one surface, and Fig. 2(B) is a cross-sectional view showing an example of a wafer having a protective member that has a ring-shaped protruding portion on the outside of one surface to protect the one surface. [Diagram 3] FIG. 2 is a perspective view showing a chuck table according to the first embodiment. [Figure 4] FIG. 2 is a plan view showing the chuck table of the first embodiment. [Diagram 5] 3 is a cross-sectional view illustrating a chuck table, a rotation mechanism, a suction force applied to the chuck table, and a supply path for water or air to the chuck table in the first embodiment. FIG. [Figure 6] FIG. 11 is a plan view showing a chuck table according to a second embodiment. [Figure 7] 1 is a plan view showing a state in which a wafer having a protective member is suction-held on a chuck table according to the first embodiment. FIG. [Figure 8] 1 is a plan view showing a state in which a wafer is suction-held on a chuck table after a protective member has been peeled off from the chuck table in the first embodiment. FIG. [Figure 9] 11 is a plan view showing a chuck table in which a frame cutout portion has a crescent shape in a plan view. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] 1 is an apparatus for grinding a wafer 80 held by suction on a chuck table 3 of the first embodiment according to the present invention using a grinding unit 16. The front (-Y direction side) on a base 10 of the grinding apparatus 1 is a carry-in / out area where the wafer 80 is carried in and out of the chuck table 3, and the rear (+Y direction side) on the base 10 is a grinding area where the wafer 80 held by suction on the chuck table 3 is ground by the grinding unit 16. The grinding apparatus may be configured to include two grinding units, a rough grinding unit and a finish grinding unit, and the chuck table 3 holding the wafer 80 on a rotating turntable can be positioned sequentially below each grinding unit.

[0012] The wafer 80 shown in Fig. 2(A) and (B) is an as-sliced ​​wafer formed by thinly slicing a cylindrical ingot made of raw material such as silicon with a wire saw or the like. The wafer 80 is not limited to the above example, and may be made of gallium arsenide, sapphire, gallium nitride, resin, ceramics, silicon carbide, or the like in addition to silicon. For example, the wafer 80 has a straight orientation flat 805, which is a mark indicating the crystal orientation, formed on the outer periphery by cutting out a part of the outer periphery flat in parallel to the tangent direction of the outer periphery. The wafer 80 may have two or more orientation flats 805 formed thereon.

[0013] The protective member 81 shown in FIGS. 2(A) and (B) is provided with a resin layer 812 that covers the entire surface of one side 801 of the wafer 80 by applying an ultraviolet-curable liquid resin onto a circular sheet 813 having a diameter larger than that of the wafer 80, spreading the liquid resin with the wafer 80, and curing the liquid resin by irradiating it with ultraviolet light. The protective member 81 is provided with a protruding portion 814 in which the sheet 813 and the resin layer 812 protrude from the outer periphery of the wafer 80. The liquid resin may be a thermosetting type. Alternatively, the liquid resin may be applied to the entire surface of one side 801 of the wafer 80, and the protective member 81 may be made of only the liquid resin. The protective member 81 may be a protective tape or a thermal adhesive sheet. The other surface 802 of the wafer 80 facing upward is the surface that is ground first in the grinding apparatus 1 .

[0014] A first cassette stage 150 and a second cassette stage 151 are provided on the front side (-Y direction side) of the base 10 of the grinding apparatus 1 shown in Figure 1 for placing cassettes capable of storing multiple wafers 80 in a shelf-like manner, and a first cassette 153 for storing multiple unprocessed wafers 80 in a shelf-like manner is placed on the first cassette stage 150, and a second cassette 154 for storing multiple processed wafers 80 in a shelf-like manner is placed on the second cassette stage 151.

[0015] 1, a robot 14 is disposed for carrying out unprocessed wafers 80 from the first cassette 153 and carrying in wafers 80 after the second grinding process into a second cassette 154. The robot 14 is provided with a robot hand 140 capable of suction-holding the wafers 80, and a multi-joint arm 141 that allows the robot hand 140 to move up and down in the Z-axis direction and to turn and move linearly within a horizontal plane (within the X-axis and Y-axis plane). The suction surface of the robot hand 140 can be turned upside down.

[0016] A temporary placement table 157 is provided adjacent to the robot 14, and the wafer 80 before grinding, which is temporarily placed on the temporary placement table 157 and held by suction, is rotated at a low speed, and images of, for example, three points on the outer periphery of the wafer are captured by a camera of a center position detection unit 156 disposed above the temporary placement table 157. Then, the center position detection unit 156 detects the exact center position of the wafer 80 by performing geometric calculation processing based on the edge coordinates of the three points on the outer periphery. The center position detection unit 156 also detects the position of an orientation flat 805 of the wafer 80 based on the captured image.

[0017] A loading arm 158 that rotates while holding a wafer 80 is disposed at a position adjacent to the temporary placement table 157. The loading arm 158 holds the wafer 80 whose position of the orientation flat 805 and center position have been detected on the temporary placement table 157, and transports the wafer 80 to the chuck table 3 that has moved close by. An unloading arm 159 that rotates while holding the processed wafer 80 is provided next to the loading arm 158. A single-wafer cleaning unit 106 that cleans the processed wafer 80 transported by the unloading arm 159 is disposed at a position adjacent to the unloading arm 159. The wafer 80 that has been subjected to the second grinding process and cleaned and dried by the cleaning unit 106 is transported into the second cassette 154 by the robot 14.

[0018] A column 102 is erected behind the grinding area on the base 10 (on the +Y side), and a grinding feed unit 17 is arranged on the front side of the column 102 on the -Y side, which feeds the grinding unit 16 in the Z-axis direction (vertical direction) for grinding. The grinding feed unit 17 comprises a ball screw 170 having an axis in the Z-axis direction, a pair of guide rails 171 arranged parallel to the ball screw 170, a motor 172 connected to the upper end of the ball screw 170 and rotating the ball screw 170, a lifting plate 173 having an internal nut that screws into the ball screw 170 and whose side is in sliding contact with the guide rail 171, and a holder 174 connected to the lifting plate 173 and holding the grinding unit 16. When the motor 172 rotates the ball screw 170, the lifting plate 173 moves back and forth in the Z-axis direction, guided by the guide rails 171, and the grinding unit 16 held by the holder 174 is fed for grinding in the Z-axis direction.

[0019] The grinding unit 16, which grinds the wafer 80 held on the chuck table 3, comprises a rotating shaft 160 whose axial direction is in the Z-axis direction, a housing 161 that rotatably supports the rotating shaft 160, a motor 162 that rotates and drives the rotating shaft 160, a circular mount 163 connected to the lower end of the rotating shaft 160, and a grinding wheel 164 that is removably attached to the underside of the mount 163.

[0020] The grinding wheel 164 includes a wheel base 165 in the form of a circular ring plate, and a plurality of segment grindstones of approximately rectangular parallelepiped shape arranged in a ring shape on the bottom surface of the wheel base 165. The segment grindstones are formed by, for example, fixing diamond abrasive grains with a resin bond, a vitrified bond, or the like. The plurality of segment grindstones arranged in a ring shape form a ring-shaped grindstone 166. A grindstone in which the segment grindstones are arranged in a ring shape with no gaps, that is, a grindstone in a so-called continuous arrangement, may be arranged on the underside of the wheel base 165.

[0021] A flow passage (not shown) for the grinding water is formed inside the rotating shaft 160, penetrating the axial direction of the rotating shaft 160. This flow passage passes through the mount 163 and opens at the bottom surface of the wheel base 165 so that the grinding water can be sprayed toward the grinding wheel 166. The sprayed grinding water reaches the contact area between the grinding wheel 166 and the wafer 80, and cools and cleans the contact area.

[0022] 1, a thickness measuring unit 18 that measures the thickness of the wafer 80 during grinding using a pair of contact-type height gauges is disposed near the grinding wheel 164 that has been lowered to a height position for grinding the wafer 80. Note that the thickness measuring unit 18 may be of a non-contact type that irradiates the wafer 80 with inspection light and measures the thickness of the wafer 80 from the optical path difference of the reflected light.

[0023] A peeling mechanism 107, shown in a simplified form, is disposed on the -X direction side of the base 10 of the grinding apparatus 1 shown in Fig. 1. The peeling mechanism 107 peels off the protective member 81 from one surface 801 of the wafer 80 after the other surface 802 has been ground in a first grinding process described below. As disclosed in Patent Document 3, for example, the peeling mechanism 107 can peel off the protective member 81 from one surface 801 of the wafer 80 by gripping a protruding portion 814 of the protective member 81 protruding from the wafer 80 with a mechanical clamp and moving the mechanical clamp and the wafer 80 so as to move them relatively apart in the horizontal or vertical direction.

[0024] 1, the grinding device 1 includes a chuck table 3 according to the present invention (hereinafter, referred to as the chuck table 3 of embodiment 1). The chuck table 3 shown in Fig. 1 and Fig. 3 includes a central suction plate 30 having a central suction surface 300, an annular suction plate 32 having an annular suction surface 320, a barrier 34 separating the outer surface of the central suction plate 30 from the inner surface of the annular suction plate 32, and a frame 31 surrounding the annular suction surface 320.

[0025] 3 and 4, the central suction plate 30 is made of a porous material such as porous ceramics, porous silicon, or porous silicon carbide, and has a circular outer periphery that is partially cut out in a straight line parallel to the tangent direction of the outer periphery. That is, since the wafer 80 shown in FIG. 1 that is held by the chuck table 3 in the present embodiment 1 has an orientation flat 805, the central suction plate 30 has a cutout portion 303 formed by cutting out a part of the outer periphery in a flat shape corresponding to the orientation flat 805. Note that if the wafer 80 has two or more orientation flats 805, the chuck table 3 may also have two or more cutout portions 303 corresponding thereto.

[0026] The barrier 34 abutting against the outer surface of the central suction plate 30 is a substantially annular wall made of a non-permeable hard material and formed in a similar shape in plan view to the outer periphery of the central suction plate 30. The upper end surface of the barrier 34 is formed flush with the central suction surface 300 of the central suction plate 30 and the annular suction surface 320 of the annular suction plate 32.

[0027] 3 and 4 is made of the same porous material as the central suction plate 30, and has a circular outer periphery and an inner periphery formed flat with a part wider toward the inside than the other parts in correspondence with the cutout part 303 of the central suction plate 30. The wider part of the upper surface of the annular suction plate 32 is part of the annular suction surface 320 and serves as an arch-shaped suction surface 322 that is arch-shaped in plan view.

[0028] 3, 4, and 5 is made of a dense material such as ceramics, and includes a frame base 311 shown in Fig. 5, which has a circular outer shape in a plan view, and an annular wall 312 standing at a predetermined height on the outer circumferential region of the upper surface of the frame base 311. The upper surface of the annular wall 312 is the upper surface of the frame 31, which is flush with the central suction surface 300, the upper surface of the barrier 34, and the annular suction surface 320.

[0029] The inner region of the annular wall 312 shown in Fig. 5 is a recess 315 in which the central suction plate 30 is housed. The central suction plate 30, the barrier 34, and the annular suction plate 32 are integrally fitted into the recess 315, and the outer surface of the annular suction plate 32 is surrounded by the annular wall 312. Also, for example, as shown in Fig. 4, a plurality of bolt insertion holes 319 (e.g., eight at 45 degree intervals) are formed at regular intervals in the circumferential direction in the outermost peripheral region of the upper surface of the frame base 311, penetrating the frame base 311 in the thickness direction (Z-axis direction). The region of the upper surface of the frame base 311 in which the bolt insertion holes 319 are formed is located below the cover 103 shown in Fig. 3.

[0030] The upper surface of the annular wall 312 of the frame 31 shown in Fig. 4 has a shape similar to that of the wafer 80 having an orientation flat 805 on the outer periphery shown in Fig. 2. That is, the portion of the annular wall 312 of the frame 31 corresponding to the notch 303 of the central suction plate 30 is cut out flat to provide a step on the outer periphery side, and is thinner than the other portions, and the upper surface of the portion of the annular wall 312 corresponding to the notch 303 is a step surface. As shown in Fig. 4, the frame 31 has an arc-shaped upper surface 313 corresponding to the arc-shaped outer periphery of the frame 31, a notch-corresponding upper surface 314 at the same height as the arc-shaped upper surface 313, and a step surface one step lower than the notch-corresponding upper surface 314, and the step portion is provided as the frame cutout portion 317.

[0031] 5, in an area corresponding to the central suction plate 30 on the bottom surface of the recess 315 of the frame body 31 (upper surface of the frame body base 311), a plurality of concentric central suction grooves 316 (only one is shown in FIG. 5) are formed so as to be centered on the center of the frame body base 311, and radial suction grooves (not shown) extend radially from the center of the frame body base 311 to connect the central suction grooves 316 to each other. In addition, in an area corresponding to the annular suction plate 32 on the outer side of the barrier 34 on the bottom surface of the recess 315 of the frame body 31, an annular suction groove 318 is formed.

[0032] As shown in FIG. 5, the chuck table 3 is fixed to the upper surface of a circular plate-shaped table base 33, and is rotatable by a rotation mechanism 38, and is capable of reciprocating movement in the Y-axis direction by a ball screw mechanism or the like (not shown).

[0033] The rotation mechanism 38 is, for example, a pulley mechanism, and includes a rotation shaft 380 that is connected to the lower surface of the table base 33 and extends perpendicularly to the chuck table 3. A driven pulley 382 is attached to the shaft of a motor 381, which serves as a drive source for rotating the rotation shaft 380, whose axial direction is in the Z-axis direction, and an endless belt 383 is wound around the driven pulley 382. A driven pulley 384 is attached to the rotation shaft 380, and the endless belt 383 is also wound around the driven pulley 384. The axis of the rotation shaft 380 coincides with the center of the upper surface of the chuck table 3, that is, the center of the circular holding surface of the chuck table 3 formed by the central suction surface 300 of the central suction plate 30 and the annular suction surface 320 of the annular suction plate 32.

[0034] A central suction passage 370 is formed from the central suction groove 316 to the rotating shaft 380 shown in Fig. 5. The central suction passage 370 is connected to a suction source 37, such as an ejector mechanism or a vacuum generator, via a rotary joint 373 arranged to surround the rotating shaft 380 and an external central suction pipe. The rotary joint 373 transfers the suction force generated by the suction source 37 to the rotating shaft 380 side without any leakage. Whether or not the chuck table 3 is suction-holding the wafer 80, for example after the protective member 81 has been peeled off, on the central suction surface 300 without any vacuum leak can be confirmed by the pressure value indicated by a pressure gauge 374 shown in Fig. 5.

[0035] The central suction pipe is provided with a central valve 378 that can switch between a state in which the central suction passage 370 is connected to, for example, the suction source 37 and a state in which it is not connected to the suction source 37. Furthermore, the central suction pipe is connected, via a three-way pipe or the like (not shown), to an air supply source 391 composed of a compressor or the like and capable of supplying compressed air, and to a water supply source 392 composed of a pump or the like and capable of sending out pure water or the like.

[0036] Further, an annular suction passage 375 is formed from the annular suction groove 318 to the rotary shaft 380. The annular suction passage 375 is connected to the suction source 37 via a rotary joint 373 and an external annular suction piping. The annular suction piping is provided with an annular valve 379 that switches the annular suction passage 375 between a state in which it is connected to the suction source 37 and a state in which it is not connected to the suction source 37. Furthermore, the annular suction piping is connected to an air supply source 391 and a water supply source 392 via a three-way pipe or the like (not shown).

[0037] For example, when the wafer 80, which is suction-held by the central suction surface 300 and the annular suction surface 320 of the chuck table 3 via the protective member 81, is to be removed from the central suction surface 300 and the annular suction surface 320, air can be supplied from the air supply source 391 to the central suction surface 300 and the annular suction surface 320 to eliminate the vacuum suction force remaining between the central suction surface 300 and the annular suction surface 320 and the protective member 81. When grinding of a plurality of wafers 80 is performed continuously and grinding chips generated from the wafer 80 are accumulated inside the central suction plate 30 or the annular suction plate 32, air may be supplied from the air supply source 391 while water is supplied from the water supply source 392, and the accumulated grinding chips may be discharged from the central suction surface 300 or the annular suction surface 320 by a two-fluid mixture of water and air.

[0038] The central suction plate 30, the barrier 34 surrounding the central suction plate 30, and the annular suction plate 32 surrounding the barrier 34 shown in Fig. 5 are fitted into the recess 315 of the frame 31, and are bonded together by an adhesive or the like (not shown) to form an integrated chuck table 3. The chuck table 3 is then placed in the grinding apparatus 1 by aligning a screw hole (not shown) formed on the upper surface of the table base 33 (see Fig. 5) arranged in the base 10 of the grinding apparatus 1 shown in Fig. 1 with a bolt insertion hole 319 of the frame base 311, and screwing and fastening a fixing bolt passing through the bolt insertion hole 319 into the screw hole of the table base 33. The central suction surface 300 of the central suction plate 30 is, for example, similar to the other surface 802 of the wafer 80 shown in Fig. 2 but slightly smaller than the other surface 802, or is congruent with the other surface 802. In addition, the upper surface (holding surface) of the chuck table 3, which is formed by combining the central suction surface 300 of the central suction plate 30, the upper end surface of the barrier 34, and the annular suction surface 320 of the annular suction plate 32, is, for example, a similar shape slightly smaller than the lower surface of the protective member 81 attached to the wafer 80, or is congruent with the lower surface of the protective member 81.

[0039] 1, in the grinding device 1, the chuck table 3 fixed to the table base 33 is surrounded by a cover 103, and can be moved back and forth in the Y-axis direction on the base 10 by a table moving means (not shown) disposed below the cover 103 and a bellows cover 104 connected to the cover 103. The table moving means (not shown) is an electric slider or the like.

[0040] The chuck table provided in the grinding apparatus 1 is not limited to the chuck table 3 of the first embodiment shown in Figures 3 to 5, and may be, for example, the chuck table 36 of the second embodiment shown in Figure 6. The chuck table 36 is used when the wafer 80 to be ground shown in Figure 2 is a completely circular wafer that does not have an orientation flat 805.

[0041] 6, the chuck table 36 of the second embodiment differs from the chuck table 3 of the first embodiment in that the central suction plate 30 of the chuck table 36 is circular and does not have the cutout portion 303, the barrier 34 is also circular and surrounds the central suction plate 30, and the annular suction plate 32 is also annular in plan view and does not have the arch-shaped suction surface 322. The annular wall 312 of the frame 31 does not have the frame cutout portion 317 shown in FIG. 4, and its upper surface is a flush annular surface. The other configurations are the same as those of the chuck table 3 of the first embodiment and the chuck table 36 of the second embodiment.

[0042] The operation of each component of the grinding apparatus 1 and each process when the grinding apparatus 1 shown in FIG. 1 is used to carry out the wafer manufacturing method according to the present invention will be described below.

[0043] (1-1) Preparation of the chuck table in the preparation process First, the chuck table 3 of embodiment 1 shown in Figure 3 is prepared in the grinding apparatus 1 shown in Figure 1, which has a central suction surface 300 having the same shape as the other surface 802 of the wafer 80 having an orientation flat 805, and an annular suction surface 320 arranged in a ring shape outside the central suction surface 300 and which suction-holds the protruding portion 814.

[0044] (1-2) Suction surface grinding process in the preparation process In this embodiment, the wafer 80 has an orientation flat 805, the protective member 81 has a circular outer shape, and the chuck table 3 of the first embodiment prepared as shown in Fig. 3 has a central suction surface 300 with a cutout portion 303 corresponding to the orientation flat 805, and a frame body 31 surrounding an annular suction surface 320, and the frame body 31 has a frame cutout portion 317 whose outer periphery is similar to that of the wafer 80. Then, a suction surface grinding process described below is performed to grind (self-grind) the entire upper surface of the chuck table 3, which is made up of the central suction surface 300, the upper surface of the barrier 34, the annular suction surface 320, and the upper surface of the frame body 31, to make the upper surface of the chuck table 3 parallel to the lower surface of the grinding wheel 166 and to bring the wafer 80 into an optimal state for grinding to a uniform thickness. The grinding wheel used to perform self-grinding is suitable for grinding the upper surface of the chuck table 3, and may be a grinding wheel different from the grinding wheel 164 used to grind the wafer 80 shown in FIG.

[0045] The chuck table 3 shown in FIG. 1 and FIG. 5 may be configured to be able to adjust the inclination of the chuck table 3 with respect to the lower surface of the grinding wheel 166 by, for example, an inclination adjustment means (not shown). For example, two or more inclination adjustment means are provided at equal intervals in the circumferential direction on the lower surface of the table base 33 shown in FIG. 5. That is, for example, two inclination adjustment means and a support column (not shown) for fixing the table base 33 are arranged at intervals of 120 degrees in the circumferential direction. The two inclination adjustment means are, for example, electric or air actuators, and are able to adjust the inclination of the chuck table 3 by moving the table base 33 up and down. The inclination of the chuck table 3 is adjusted in order to perform self-grinding of the chuck table 3, for example, to form the upper surface of the chuck table 3 after self-grinding into an extremely gentle conical inclination with the center of the central suction surface 300 as the apex, which is indiscernible to the naked eye, and to enable grinding water to be appropriately discharged from the contact portion between the grinding wheel 166 and the wafer 80.

[0046] 1 in the +Y direction, the center of rotation of the grinding wheel 164 of the grinding unit 16 is shifted by a predetermined distance in the horizontal direction from the center of rotation 309 of the chuck table 3 shown in Fig. 4, and the grinding wheel 166 is positioned so that the grinding wheel trajectory of the rotating grinding wheel 166 can pass through the center of rotation 309 of the rotating chuck table 3. The center of rotation 309 of the chuck table 3 is a point on the central suction surface 300 that is equidistant from the outer periphery, which is a circle, of the central suction surface 300.

[0047] Next, the motor 162 shown in FIG. 1 rotates the rotating shaft 160 at a predetermined rotation speed, and the grinding wheel 164 also rotates in a clockwise direction as viewed from the +Z direction side. Then, the grinding unit 16 is sent in the -Z direction by the grinding feed unit 17, and the rotating grinding wheel 166 comes into contact with the central suction surface 300, the upper surface of the barrier 34, the annular suction surface 320, and the upper surface of the frame body 31, thereby performing grinding. During grinding, the chuck table 3 is also rotated in a clockwise direction as viewed from the +Z direction side by the rotation mechanism 38, so that the grinding wheel 166 grinds the entire surfaces of the central suction surface 300, the upper surface of the barrier 34, the annular suction surface 320, and the upper surface of the frame body 31. Grinding water is also supplied to the grinding wheel 166 to cool and wash the contact area. Then, after the entire upper surface of the chuck table 3 has been self-ground for a predetermined period of time, the grinding wheel 166 rises and moves away from the chuck table 3, so that the upper surface of the chuck table 3 is formed into an extremely gentle conical slope, with the apex being the center of the central suction surface 300 and so shallow that it is impossible to see with the naked eye.

[0048] 4 is shorter than the length of the grindstone path R23 that does not pass through the frame cutout 317, the grinding pressure with which the grinding wheel 166 presses the chuck table 3 downward increases in the grindstone path area that passes through the frame cutout 317. Therefore, by the grinding wheel 166 grinding more of the upper surface of the chuck table 3 in the grindstone path area that passes through the frame cutout 317 than in the grindstone path area that does not pass through the frame cutout 317, the height of the grindstone path area that passes through the frame cutout 317 on the upper surface of the chuck table 3 after grinding can be formed lower than the height of the grindstone path area that does not pass through the frame cutout 317.

[0049] (2) First grinding process 1 is suction-held by the central suction surface 300 and the annular suction surface 320 of the chuck table 3 after self-grinding, and a first grinding step is performed in which the other surface 802 facing upward of the wafer 80 is ground by the grinding wheel 166. Specifically, first, the robot 14 shown in FIG. 1 pulls out one wafer 80 from the first cassette 153 and moves the wafer 80 to the temporary placement table 157. Next, after the center position detection unit 156 detects the center of the wafer 80 and the orientation flat 805, the loading arm 158 suction-holds the other surface 802 of the wafer 80 and transports it onto the chuck table 3.

[0050] The wafer 80 is aligned so that the center of rotation 309 of the central suction surface 300 of the chuck table 3 and the center of the wafer 80 are substantially aligned, and the notch 303 and the orientation flat 805 of the wafer 80 are substantially aligned. Thereafter, the loading arm 158 descends, and the wafer 80 is placed on the central suction surface 300 via the protective member 81, as shown in FIG. 7, and the protective member 81 is placed on the central suction surface 300 and the annular suction surface 320. The protective member 81 is placed with the protruding portion 814 protruding slightly from the upper surface of the frame 31. The center of the wafer 80 is a point on the outer periphery of the wafer 80 that is equidistant from the arc-shaped outer periphery. That is, the center of the wafer 80 is the center of a circle when the orientation flat 805 is not formed on the wafer 80 and the outer periphery is a perfect circle.

[0051] After the wafer 80 is placed on the chuck table 3, with the central valve 378 and the annular valve 379 shown in FIG. 5 being open, the suction force generated by the operation of the suction source 37 is transmitted to the central suction surface 300 and the annular suction surface 320, and the wafer 80 is suction-held by the chuck table 3 via the protective member 81. Thereafter, the chuck table 3 holding the wafer 80 moves in the +Y direction to below the grinding unit 16. Then, the grinding wheel 166 is positioned so that the rotation trajectory passes through the rotation center 309 of the chuck table 3.

[0052] The grinding wheel 164 shown in FIG. 1 rotates at a predetermined rotation speed, for example, in a clockwise direction as viewed from the +Z direction side. Then, the grinding unit 16 descends, and the rotating grinding wheel 166 comes into contact with the other surface 802 of the wafer 80 facing upward, thereby performing grinding. During grinding, the chuck table 3 shown in FIG. 7 rotates, for example, in a clockwise direction as viewed from the +Z direction side, and the wafer 80 suction-held on the central suction surface 300 and the annular suction surface 320 via the protective member 81 also rotates, so that the grinding wheel 166 performs grinding processing (for example, inner and outer grinding processing as in this embodiment) on the entire surface of the other surface 802 of the wafer 80. In addition, grinding water is supplied to the contact portion between the grinding wheel 166 and the wafer 80, and the contact portion is cooled and washed.

[0053] Here, as shown in FIG. 7, the protruding portion 814 of the protective member 81 is held by suction by the annular suction surface 320 and the arched suction surface 322, so that the protruding portion 814 does not flutter during grinding and is prevented from coming into contact with the grinding wheel 166 shown in FIG. 1.

[0054] 7 has an orientation flat 805 indicating a crystal orientation, the chuck table 3 of the first embodiment is provided with the frame cutout 317 in the frame 31, and therefore the wafer 80 can be ground to a uniform thickness. Here, for example, assume that the chuck table 3 of the first embodiment does not have the frame cutout 317 and that the top surface of the frame 31 is flush with no steps. Then, when the wafer 80 is sucked and held on the self-ground central suction surface 300 of a chuck table 3 assumed not to have the frame cutout portion 317, via the protective member 81, and the other surface 802 of the wafer 80 is ground with the grinding wheel 166, the length of the grinding wheel path R11 passing through the center of the wafer 80, which coincides with the rotation center 309 of the chuck table 3, and the orientation flat 805 of the wafer 80, is shorter than the length of the grinding wheel path R13 that does not pass through the orientation flat 805. Therefore, in the grinding wheel path area that passes through the orientation flat 805, the grinding pressure with which the grinding wheel 166 presses the wafer 80 toward the central suction surface 300 increases. As a result, the grinding wheel 166 grinds more in the grinding wheel path area that passes through the orientation flat 805 of the wafer 80 than in other areas, resulting in a problem in that the thickness of the area corresponding to the orientation flat 805 of the wafer 80 after grinding becomes thinner than the other areas.

[0055] However, in the chuck table 3 of the present embodiment 1 shown in Fig. 7, in order to prevent the grinding pressure applied to the wafer 80 from being higher than that in other grinding wheel path areas even in the grinding wheel path area passing through the orientation flat 805 of the wafer 80 in this first grinding step, the annular wall 312 of the frame 31 has a frame cutout 317 formed by cutting out a part of the annular wall 312 on the upper surface of the portion corresponding to the cutout 303 of the central suction plate 30. Then, the chuck table 3 having the frame cutout 317 shown in Fig. 7 is self-ground in the preparation step described above, so that the heights of the central suction surface 300, the bow-shaped suction surface 322, and the notched portion corresponding upper surface 314 of the frame 31 corresponding to the grinding wheel path area passing through the frame cutout 317 are lower than the other areas where the grinding wheel path does not pass through the respective frame cutouts 317. Therefore, when the wafer 80 held by the central suction surface 300 of the chuck table 3 after the self-grinding is ground, the portion of the wafer 80 corresponding to the orientation flat 805 is ground in a state where it is lower than the other portions relative to the lower surface of the grinding wheel 166 shown in Fig. 1, so that it is possible to reduce the amount by which the thickness of the portion of the wafer 80 corresponding to the orientation flat 805 after grinding becomes thinner than the other portions. In other words, it is possible to make the wafer 80 after grinding have a more uniform thickness. In Figures 4, 7 and 8, frame body cutout portion 317 has a bow shape in which the inner side is straight and the outer side is an arc when viewed in a plane, but as shown in Figure 9, frame body cutout portion 317 may have a crescent shape in which the inner side is arc-shaped and the outer side is also an arc when viewed in a plane. In this way, the grinding pressure with which the grinding wheel 166 presses the chuck table 3 downward (the grinding pressure with which the wafer 80 is pressed downward) is made uniform in the grinding wheel trajectory area that passes through the frame cutout portion 317. After the wafer 80 has been ground for a predetermined time in this manner, the grinding unit 16 shown in FIG. 1 is pulled upward, the grinding wheel 166 is separated from the wafer 80, and grinding of the other surface 802 is completed.

[0056] (3) Peeling process After the first grinding step is completed, the chuck table 3 is sent in the -Y direction, and the unloading arm 159 shown in Fig. 1 suction-holds the other surface 802 of the wafer 80 after grinding, which faces upward, and then moves the wafer 80 to the cleaning unit 106. Then, in the cleaning unit 106, mainly the other surface 802 of the wafer 80 is cleaned for a predetermined period of time, and then the wafer 80 is air-dried or spin-dried.

[0057] 1 lifts the wafer 80, which is held by suction on the spinner table of the cleaning unit 106, after holding it by suction using a suction pad or the like. Then, the protruding portion 814 of the protective member 81 exposed downward and protruding from the wafer 80 is gripped by a mechanical clamp or the like, and the mechanical clamp and the wafer 80 are moved so as to move relatively apart in the horizontal or vertical direction, thereby peeling the protective member 81 from one surface 801, which is the underside of the wafer 80.

[0058] (4) Second grinding process 1, and then is carried out of the cleaning unit 106 by the robot 14. During the transfer, the robot hand 140, which has been suction-holding the other surface 802 of the wafer 80 from above, is turned upside down so that the one surface 801 of the wafer 80 from which the protective material 81 has been peeled off faces upward.

[0059] 1, the robot hand 140 descends above the temporary placement table 157, and the temporary placement table 157, which has a diameter smaller than the U-shaped opening of the robot hand 140, enters the opening, and the suction surface of the temporary placement table 157 comes into contact with the other surface 802 facing downward of the wafer 80. Next, the loading arm 158 suction-holds one surface 801 of the wafer 80 placed on the temporary placement table 157 from above, and transports the wafer 80 onto the chuck table 3. In addition, if the spinner table of the cleaning unit 106 has a smaller diameter than the U-shaped opening of the robot hand 140 of the robot 14, the robot 14 may receive the wafer 80 from the spinner table by suction-holding one side 801 of the wafer 80 from below, and then turn the robot hand 140 upside down and suction-hold the other side 802 of the wafer 80 on the suction surface of the temporary placement table 157.

[0060] 8, the center of rotation 309 of the central suction surface 300 of the chuck table 3 and the center of the wafer 80 are aligned substantially, and the notch 303 and the orientation flat 805 of the wafer 80 are aligned substantially. Then, the loading arm 158 shown in FIG. 1 is lowered to place the wafer 80 on the central suction surface 300, with the outer periphery of the wafer 80 slightly protruding from the upper surface of the barrier 34.

[0061] After the wafer 80 is placed on the chuck table 3, the central valve 378 shown in Fig. 5 is opened and the annular valve 379 is closed. In this state, the suction source 37 (see Fig. 5) is operated to generate a suction force, which is transmitted to the central suction surface 300, and the other surface 802 of the wafer 80 is sucked and held by the central suction surface 300. Then, the chuck table 3 moves in the +Y direction to below the grinding unit 16 shown in Fig. 1. Then, the grinding wheel 166 is aligned so that the rotation trajectory passes through the center of the wafer 80.

[0062] Then, the grinding unit 16 descends, and the grinding wheel 166, which rotates, for example, clockwise when viewed from the +Z direction side, comes into contact with one side 801 of the wafer 80, thereby performing grinding. During grinding, the chuck table 3 rotates, for example, clockwise when viewed from the +Z direction side, and the wafer 80 held by suction on the central suction surface 300 also rotates, so that the grinding wheel 166 grinds the entire surface of one side 801 of the wafer 80. Grinding water is also supplied to the contact area between the grinding wheel 166 and the wafer 80 to cool and clean the contact area. Here, as in the first grinding process, the grinding pressure applied to the wafer 80 on the grinding wheel path R11 that passes through the orientation flat 805 of the wafer 80 does not increase more than that on the grinding wheel path R13 that does not pass through the orientation flat 805, so the amount by which the thickness of the portion of the wafer 80 corresponding to the orientation flat 805 after grinding becomes thinner than the other portions can be reduced by using the self-ground chuck table 3 of embodiment 1. In other words, it is possible to make the wafer 80 have a uniform thickness after grinding.

[0063] The grinding wheel 166 moves away from the wafer 80 which has reached the finishing thickness upon completion of the second grinding step, and the unloading arm 159 shown in FIG. 1 removes the wafer 80 from the chuck table 3 and transports it to the cleaning unit 106. After cleaning of the wafer 80 is completed, the robot 14 removes the wafer 80 from the cleaning unit 106 and stores it in the second cassette 154.

[0064] As described above, in the method for manufacturing a wafer according to the present invention, the first grinding step is performed in which the other surface 802 of the wafer 80 is ground by the grinding wheel 166 while the protective member 81 is held by suction between the central suction surface 300 and the annular suction surface 320 of the chuck table 3 to prevent flapping, and after the protective member 81 is peeled off from the wafer 80 ground in the first grinding step, the other surface 802 of the wafer 80 is held by suction only by the central suction surface 300, and one surface 801 of the wafer 80 is ground by the grinding wheel 166. Therefore, the protective member 81 does not come into contact with the grinding wheel 166. Therefore, the grinding force of the grinding wheel 166 is not reduced.

[0065] The steps of the wafer manufacturing method and the chuck table according to the present invention are not limited to the above-described embodiment, and may be implemented in various different forms within the scope of the technical concept. Furthermore, the components of the grinding device 1 used in the wafer manufacturing method and on which the chuck table is disposed may be modified as appropriate within the scope of the effects of the present invention.

[0066] 2 to be ground by the grinding apparatus 1 is, for example, a wafer 80 having a circular circumference without an orientation flat 805, the chuck table disposed in the grinding apparatus 1 may be the chuck table 36 of the second embodiment shown in FIG. 6 instead of the chuck table 3 of the first embodiment. Even in this case, the method for manufacturing a wafer according to the present invention performs a first grinding step in which the protective member 81 is held by suction between the central suction surface 300 and the annular suction surface 320 of the chuck table 36 and does not flap during grinding, and the other surface 802 of the wafer 80 is ground by the grinding wheel 166 after the protective member 81 is peeled off from the wafer 80 ground in the first grinding step. Therefore, the other surface 802 of the wafer 80 is held by suction only between the central suction surface 300, and one surface 801 of the wafer 80 is ground by the grinding wheel 166. Therefore, the protective member 81 does not come into contact with the grinding wheel 166. Therefore, the grinding power of the grinding wheel 166 is not reduced. [Explanation of symbols]

[0067] 1: Grinding device 10: Base 102: Column 106: Cleaning unit 107: Peeling mechanism 14:Robot 140:Robot Hand 150: First cassette stage 151: Second cassette stage 156: Center position detection unit 157: Temporary placement table 158: Loading arm 159: Unloading arm 16: Grinding unit 160: Rotating shaft 162: Motor 164: Grinding wheel 17: Grinding feed unit 18: Thickness measurement unit 3: Chuck table of embodiment 1 30: Central suction plate 300: Central suction surface 303: Notch 31: Frame 311: Frame base 312: Annular wall 313: Arc-shaped upper surface 314: Upper surface corresponding to the notched portion 317: Frame cutout portion 32: Annular suction plate 320: Annular suction surface 322: Arched suction surface 33: Table base 34: Barrier 37: Suction source 370: Central suction passage 373: Rotary joint 374: Pressure gauge 375: Annular side suction passage 378: Central valve 379: Annular valve 38: Rotation mechanism 391: Air supply source 392: Water supply source 36: Chuck table of embodiment 2 80: Wafer 801: One side 802: Other side 805: Orientation flat 81: Protective member 813: Sheet 812: Resin layer 814: Protruding portion

Claims

1. A method for manufacturing a wafer having a uniform thickness, the method comprising the steps of: grinding one surface and the other surface of a wafer, the one surface of the wafer having a protective member that is provided with an annular protruding portion on the outside of the one surface of the wafer and protects the one surface, with a grinding wheel; a preparation step of preparing a chuck table for a grinding device for grinding the wafer, the chuck table having a central suction surface having the same shape as the other surface of the wafer and an annular suction surface disposed annularly outside the central suction surface and suction-holding the protruding portion; a first grinding step of suction-holding the protective member between the central suction surface and the annular suction surface and grinding the other surface of the wafer with the grinding wheel; a peeling step of peeling off the protective member from the wafer ground in the first grinding step; a second grinding step in which, after the peeling step, the other surface of the wafer is suction-held only by the central suction surface and the one surface of the wafer is ground by the grinding wheel.

2. the wafer includes an orientation flat; The protective member has a circular outer shape, the chuck table prepared in the preparing step has a notch portion on the central suction surface corresponding to the orientation flat, and has a frame body surrounding the annular suction surface, the frame has an outer periphery similar in shape to the wafer and is provided with a frame cutout portion; 2. The method for manufacturing a wafer according to claim 1, wherein the preparation step includes a suction surface grinding step of grinding the central suction surface and the annular suction surface with the grinding wheel.

3. A chuck table for use in the method for manufacturing a wafer according to claim 2, a central suction plate having the central suction surface, an annular suction plate having the annular suction surface, and a barrier separating an outer surface of the central suction plate from an inner surface of the annular suction plate, the frame has a recess for accommodating the central suction plate, the barrier and the annular suction plate, and surrounds the outer periphery of the annular suction plate; The central suction plate is a chuck table having a cutout portion corresponding to the orientation flat of the wafer.

Images