chuck table

Abstract

The present invention provides a chuck stage that can grind a wafer to a uniform thickness. The chuck stage (3) has a holding surface (302) having a notch (303) corresponding to the orientation plane (805) of the wafer (80). The chuck stage is used for grinding in the following way: an annular grinding tool can pass through the center of the arc-shaped outer periphery of the holding surface and grind the wafer in an arc-shaped grinding tool trajectory from the center of the wafer held on the holding surface to the outer periphery. The chuck stage has a frame (31) for receiving the perforated portion (30). The ratio of the length of the grinding tool trajectory on the holding surface when passing through the arc-shaped outer periphery of the holding surface of the perforated portion to the length on the upper surface of the frame is used to form a straight line connecting the outer periphery position of the frame in the grinding tool trajectory at one end of the notch and the outer periphery position of the frame in the grinding tool trajectory at the other end of the notch as the edge of the outer periphery of the frame.

Description

TECHNICAL FIELD

[0001] The present application relates to a chuck table that holds a wafer having a directional plane. BACKGROUND

[0002] A grinding device that grinds a wafer with a ring-shaped grinding tool holds the wafer by suction using a holding surface of a chuck table that transmits the suction force. Figure 8 The conventional chuck table 37 shown (see, for example, Patent Document 1) is composed of a plurality of holes 370 of a circular plate with an upper surface as a holding surface 372 that is an exposed surface, and a frame 373 that houses the plurality of holes 370 so that the holding surface 372 is exposed.

[0003] Further, the holding surface 372 is formed in the same shape as the wafer 80 in correspondence with a directional plane 805 that indicates the crystal orientation formed in the wafer 80. That is, the outer periphery of the plurality of holes 370 is cut flat in correspondence with the directional plane 805, and in contrast, since the outer periphery of the frame 373 is circular, the upper surface of the frame 373 in correspondence with the position where the outer periphery of the plurality of holes 370 is missing is larger than the upper surface of the frame 373 at other positions.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2012-134275

[0005] By grinding the upper surface of the conventional chuck table 37 disclosed in Patent Document 1, that is, the holding surface 372 and the upper surface of the frame 373, with the lower surface of a rotating grinding tool, self-grinding that forms the upper surface of the chuck table 37 parallel to the lower surface of the grinding tool is performed.

[0006] When the holding surface 372 after self-grinding holds the wafer 80 by suction and grinds the wafer 80 with the grinding tool, the length of the grinding tool trace R376 that passes through the directional plane 805 of the wafer 80 becomes shorter than the length of the grinding tool trace R377 that does not pass through the directional plane 805 of the wafer 80, and therefore in the area of the grinding tool trace that passes through the directional plane 805 of the wafer 80, the grinding pressure of the grinding tool against the wafer 80 that presses the wafer 80 toward the holding surface 372 increases, and the grinding tool further grinds the wafer 80, and there is a problem that the portion of the wafer 80 after grinding that corresponds to the directional plane 805 becomes thinner than other portions.

[0007] Therefore, in a chuck table that holds a wafer 80 having a directional plane 805 by suction with a grinding tool, there is a problem that the wafer 80 cannot be ground to a uniform thickness. SUMMARY

[0008] The chuck table of the present application for solving the above problem is a chuck table having a holding surface formed with a linear notch portion cut out in correspondence with a directional plane in a manner to become a similar shape to an upper surface of a wafer having the directional plane as a ground surface, for grinding processing in which a circular grinding tool is capable of passing through the center of the circular arc-shaped outer periphery of the holding surface, making the center of the circular arc-shaped outer periphery of the holding surface coincide with the center of the wafer, and making the holding surface coincide with the shape of the wafer, and grinding the wafer in a circular arc-shaped tool track from the center of the wafer held on the holding surface to the outer periphery, wherein the chuck table has a porous portion having the holding surface, and a frame body housing the porous portion with the holding surface exposed, and the frame body is formed in a manner to make the ratio of the length of the tool track on the holding surface to the length on the upper surface of the frame body uniform.

[0009] In addition, the chuck table of the present application for solving the above problem is a chuck table having a holding surface formed with a linear notch portion cut out in correspondence with a directional plane in a manner to become a similar shape to an upper surface of a wafer having the directional plane as a ground surface, for grinding processing in which a circular grinding tool is capable of passing through the center of the circular arc-shaped outer periphery of the holding surface, making the center of the circular arc-shaped outer periphery of the holding surface coincide with the center of the wafer, and making the holding surface coincide with the shape of the wafer, and grinding the wafer in a circular arc-shaped tool track from the center of the wafer held on the holding surface to the outer periphery, wherein the chuck table has a porous portion having the holding surface, and a frame body housing the porous portion with the holding surface exposed, and the frame body is formed in a manner to make the ratio of the length of the tool track on the upper surface of a predetermined wafer held by the holding surface to a second ratio of a length obtained by adding the length on the holding surface as the upper surface of the chuck table and the length on the upper surface of the frame body uniform.

[0010] A chuck table according to the present application is a chuck table having a holding surface formed with a linear notch portion cut out in correspondence with a directional plane in a manner that the holding surface becomes similar in shape to an upper surface of a wafer having the directional plane as a surface to be ground, for grinding processing in which a circular grinding tool is capable of passing through the center of a circular arc-shaped outer periphery of the holding surface, the center of the circular arc-shaped outer periphery of the holding surface is made to coincide with the center of the wafer, and the holding surface is made to coincide with the shape of the wafer, and the wafer is ground in a circular arc-shaped tool track of the outer periphery from the center of the wafer held on the holding surface, wherein the chuck table has a porous portion having the holding surface, and a frame body housing the porous portion with the holding surface exposed, and a length of the tool track on the holding surface when passing through the circular arc-shaped outer periphery of the holding surface and a length obtained by adding a length of the tool track on the holding surface as an upper surface of the chuck table and a length of the tool track on an upper surface of the frame body are compared, and a straight line linking an outer periphery position of the frame body at which the comparison is established in the tool track passing through one end of the notch portion and an outer periphery position of the frame body at which the comparison is established in the tool track passing through the other end of the notch portion is used as an edge of the outer periphery of the frame body.

[0011] A chuck table according to the present application is a chuck table having a holding surface formed with a linear notch portion cut out in correspondence with a directional plane in a manner that the holding surface becomes similar in shape to an upper surface of a wafer having the directional plane as a surface to be ground, for grinding processing in which a circular grinding tool is capable of passing through the center of a circular arc-shaped outer periphery of the holding surface, the center of the circular arc-shaped outer periphery of the holding surface is made to coincide with the center of the wafer, and the holding surface is made to coincide with the shape of the wafer, and the wafer is ground in a circular arc-shaped tool track of the outer periphery from the center of the wafer held on the holding surface, wherein the chuck table has a porous portion having the holding surface, and a frame body housing the porous portion with the holding surface exposed, and a length of the tool track on an upper surface of a predetermined wafer held on the holding surface when passing through the circular arc-shaped outer periphery of the holding surface and a length obtained by adding a length of the tool track on the holding surface as an upper surface of the chuck table and a length of the tool track on an upper surface of the frame body are compared, and a straight line linking an outer periphery position of the frame body at which the comparison is established in the tool track passing through one end of the directional plane of the predetermined wafer held on the holding surface and an outer periphery position of the frame body at which the comparison is established in the tool track passing through the other end of the directional plane of the predetermined wafer held on the holding surface is used as an edge of the outer periphery of the frame body.

[0012] The holding surface of the chuck table according to the present application is, for example, the same in shape and the same in size as the upper surface of the wafer as the surface to be ground.

[0013] The chuck table of the present application has a holding surface formed with linear-shaped cutout portions corresponding to the orientation flat in a similar shape (e.g., congruent) to the upper surface of a wafer having an orientation flat as a ground surface, and is used for grinding processing in which a ring-shaped grinding tool can pass through the center of the circular-arc-shaped outer periphery of the holding surface, align the center of the circular-arc-shaped outer periphery of the holding surface with the center of the wafer, and align the holding surface with the shape of the wafer, and grind the wafer in a grinding tool track of the circular-arc-shaped outer periphery from the center of the wafer held on the holding surface to the outer periphery, wherein the chuck table has a porous portion having the holding surface, and a frame body housing the porous portion with the holding surface exposed, and the frame body is formed in a manner that the length ratio of the grinding tool track on the holding surface and on the upper surface of the frame body is uniform, whereby the grinding pressure applied to the wafer is not increased in the grinding tool track area of the orientation flat of the wafer held on the holding surface, and the ground wafer can be made to have a uniform thickness.

[0014] In addition, the chuck table of the present application has a holding surface formed with linear-shaped cutout portions corresponding to the orientation flat in a similar shape to the upper surface of a wafer having an orientation flat as a ground surface, and is used for grinding processing in which a ring-shaped grinding tool can pass through the center of the circular-arc-shaped outer periphery of the holding surface, align the center of the circular-arc-shaped outer periphery of the holding surface with the center of the wafer, and align the holding surface with the shape of the wafer, and grind the wafer in a grinding tool track of the circular-arc-shaped outer periphery from the center of the wafer held on the holding surface to the outer periphery, wherein the chuck table has a porous portion having the holding surface, and a frame body housing the porous portion with the holding surface exposed, and the frame body is formed in a manner that the length ratio of the grinding tool track on the upper surface of a predetermined wafer held by the holding surface and a second ratio of the length obtained by adding the length on the holding surface as the upper surface of the chuck table and the length on the upper surface of the frame body is uniform, whereby the grinding pressure applied to the wafer is not increased in the grinding tool track area of the orientation flat of the wafer held on the holding surface, and the ground wafer can be made to have a uniform thickness.

[0015] In addition, the chuck table of the present application has a holding surface formed with linear-shaped cutout portions corresponding to the orientation flat in a similar shape (e.g., congruent) to the upper surface of a wafer having an orientation flat as a ground surface, and is used for grinding processing in which a ring-shaped grinding tool can pass through the center of the circular-arc-shaped outer periphery of the holding surface, align the center of the circular-arc-shaped outer periphery of the holding surface with the center of the wafer, and align the holding surface with the shape of the wafer, and grind the wafer in a grinding tool track of the circular-arc-shaped outer periphery from the center of the wafer held on the holding surface to the outer periphery, wherein the chuck table has a porous portion having the holding surface, and a frame body housing the porous portion with the holding surface exposed, the length of the grinding tool track on the holding surface when passing through the circular-arc-shaped outer periphery of the holding surface is compared with the length on the upper surface of the frame body, a straight line linking the outer periphery position of the frame body where the second comparison is established in the grinding tool track passing through one end of the cutout portion and the outer periphery position of the frame body where the second comparison is established in the grinding tool track passing through the other end of the cutout portion is taken as the edge of the outer periphery of the frame body, and thus, even in the grinding tool track area passing through the orientation flat of the wafer held on the holding surface, the grinding pressure applied to the wafer is not increased, and the ground wafer can be made to have a uniform thickness.

[0016] In addition, the chuck table of the present application has a holding surface formed with linear-shaped cutout portions corresponding to the orientation flat in a similar shape (e.g., congruent) to the upper surface of a wafer having an orientation flat as a ground surface, and is used for grinding processing in which a ring-shaped grinding tool can pass through the center of the circular-arc-shaped outer periphery of the holding surface, align the center of the circular-arc-shaped outer periphery of the holding surface with the center of the wafer, and align the holding surface with the shape of the wafer, and grind the wafer in a grinding tool track of the circular-arc-shaped outer periphery from the center of the wafer held on the holding surface to the outer periphery, wherein the chuck table has a porous portion having the holding surface, and a frame body housing the porous portion with the holding surface exposed, the length of the grinding tool track on the holding surface when passing through the circular-arc-shaped outer periphery of the holding surface is compared with the length on the upper surface of the frame body, a straight line linking the outer periphery position of the frame body where the second comparison is established in the grinding tool track passing through one end of the cutout portion and the outer periphery position of the frame body where the second comparison is established in the grinding tool track passing through the other end of the cutout portion is taken as the edge of the outer periphery of the frame body, and thus, even in the grinding tool track area passing through the orientation flat of the wafer held on the holding surface, the grinding pressure applied to the wafer is not increased, and the ground wafer can be made to have a uniform thickness. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1This is a perspective view showing an example of a grinding apparatus having a chuck table according to Embodiment 1.

[0018] Figure 2 This is an exploded perspective view showing the chuck worktable of Embodiment 1.

[0019] Figure 3 This is a perspective view showing the chuck worktable of Embodiment 1.

[0020] Figure 4 This is a top view illustrating the chuck worktable of Embodiment 1. In this chuck worktable, a second ratio is used to obtain the length of the grinding wheel trajectory on the upper surface of the wafer to be held by the holding surface when passing through the arc-shaped outer periphery of the holding surface, which is obtained by adding the length of the grinding wheel trajectory on the holding surface of the chuck worktable and the length on the upper surface of the frame. The straight line obtained by connecting the outer periphery position of the frame that is equal to the second ratio in the grinding wheel trajectory at one end of the orientation plane of the wafer to be held by ...

[0021] Figure 5 This is a top view illustrating the chuck worktable before the improvement of the chuck worktable in Embodiment 1.

[0022] Figure 6 This is a top view of the outer periphery of the frame of each of the chuck worktables in Embodiment 1, Embodiment 2, Embodiment 3, and Embodiment 4.

[0023] Figure 7 This is used to describe the outer periphery of the frame of each of the chuck worktables in Embodiment 1, Embodiment 2, Embodiment 3, and Embodiment 4. Figure 6 A magnified top view of a portion of the image.

[0024] Figure 8 This is a top view illustrating the existing chuck stage for holding the wafer.

[0025] Label Explanation

[0026] 80: Wafer; 801: Front side of the wafer; 802: Grinding surface of the wafer; 805: Orientation plane; 1: Grinding apparatus; 10: Base; 12: Column; 150: First box stage; 151: Second box stage; 21: First box; 22: Second box; 155: Robot; 152: Temporary stage; 153: Imaging unit; 154: Loading arm; 157: Unloading arm; 156: Cleaning unit; 17: Grinding feed unit; 16: Grinding unit; 166: Grinding wheel; 54: Thickness measurement unit; 3: Chuck stage of embodiment 1; 30: Perforated Part; 302: Holding surface; 3022: Center of holding surface; 303: Notch; 304: Arc-shaped outer periphery; 31: Frame; 311: Base of frame; 3112: Bolt insertion hole; 312: Annular wall; 313: Arc-shaped upper surface; 314: Upper surface corresponding to notch; 315: Recess; 3154: Suction groove; 3155: Suction hole; 52: Chuck worktable rotation unit; 50: Cover; 500: Folded cover; 38: Chuck worktable of Embodiment 2; 33: Chuck worktable of Embodiment 3; 34: Chuck worktable of Embodiment 4. Detailed Implementation

[0027] Figure 1 The grinding apparatus 1 shown is an apparatus for grinding a wafer 80 held on a chuck table 3 in Embodiment 1 of the present invention by means of a grinding unit 16. The front (-Y direction side) of the base 10 of the grinding apparatus 1 becomes the area for loading and unloading the wafer 80 onto and off the chuck table 3, namely the loading and unloading area 100, and the rear (+Y direction side) of the base 10 becomes the area for grinding the wafer 80 held on the chuck table 3 by means of the grinding unit 16, namely the grinding area 101.

[0028] Alternatively, the processing apparatus of the present invention may be configured to have two axes as grinding units, namely a rough grinding unit and a fine grinding unit, and to use a rotating turntable to position the chuck table 3 holding the wafer 80 below each grinding unit.

[0029] In this embodiment, Figure 1 The wafer 80 shown is a roughly circular semiconductor wafer formed from silicon substrate or the like. Figure 1 Multiple devices are formed on the front side 801 of the wafer 80 facing downwards, and are protected by a protective strip (not shown). The back side, i.e., the upper surface, of the wafer 80 facing upwards serves as the grinding surface 802 to be ground. In addition to silicon, the wafer 80 can also be formed of gallium arsenide, sapphire, gallium nitride, resin, ceramic, or silicon carbide.

[0030] like Figure 1As shown, in the outer periphery of the wafer 80, an orientation plane 805 is formed by cutting a portion of the outer periphery flatly, parallel to the tangential direction of the outer periphery. This plane is a straight line that serves as a marker for crystal orientation.

[0031] On the front side (-Y direction side) of the base 10 of the grinding apparatus 1, there are a first box stage 150 and a second box stage 151 for holding boxes that can hold multiple wafers 80 in a shelf-like manner. The first box stage 150 holds a first box 21 that holds multiple wafers 80 before processing in a shelf-like manner, and the second box stage 151 holds a second box 22 that holds multiple wafers 80 after processing in a shelf-like manner.

[0032] A robot 155 is positioned behind the opening on the +Y direction side of the first box 21. This robot 155 removes the unprocessed wafer 80 from the first box 21 and moves the processed wafer 80 into the second box 22. A temporary placement stage 152 is positioned adjacent to the robot 155. The unprocessed wafer 80, temporarily placed on the temporary placement stage 152, is... Figure 1 The imaging unit 153 shown takes pictures, and based on the formed images, the position of the orientation plane 805 and the center position of the wafer 80 are identified by the control unit (not shown) of the grinding device 1.

[0033] A loading arm 154, which rotates while holding a wafer 80, is positioned adjacent to the temporary stage 152. The loading arm 154 holds the wafer 80, which has its orientation plane 805 positioned in the temporary stage 152, and transports it to the chuck table 3 located nearby. Next to the loading arm 154, an unloading arm 157, which rotates while holding the processed wafer 80, is positioned. A single-sheet cleaning unit 156 is positioned close to the unloading arm 157 to clean the processed wafer 80 transported by the unloading arm 157. The wafer 80, cleaned and dried by the cleaning unit 156, is then transferred to the second cassette 22 by a robot 155.

[0034] A column 12 is erected behind the grinding area 101 (on the +Y direction side). A grinding feed unit 17 is provided on the front surface of the column 12 on the -Y direction side. The grinding feed unit feeds the grinding unit 16 and the chuck table 3 relative to each other in the Z-axis direction (vertical direction) perpendicular to the holding surface 302. The grinding feed unit 17 includes: a ball screw 170 having a Z-axis axis; 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 to rotate the ball screw 170; a lifting plate 173 with a nut inside screwed into the ball screw 170 and its side slidingly contacting the guide rails 171; and a cage 174 connected to the lifting plate 173 to hold the grinding unit 16. When the motor 172 rotates the ball screw 170, the lifting plate 173 is guided by the guide rails 171 to reciprocate in the Z-axis direction, and the grinding unit 16 held by the cage 174 performs grinding feed in the Z-axis direction.

[0035] The grinding unit 16 for grinding the wafer 80 held on the chuck table 3 includes: a rotating shaft 160 with its axis in the Z-axis direction; a housing 161 that supports the rotating shaft 160 so that it can rotate; a motor 162 that drives the rotating shaft 160 to rotate; an annular mounting base 163 that is connected to the lower end of the rotating shaft 160; and a grinding wheel 164 that is detachably mounted on the lower surface of the mounting base 163.

[0036] The grinding wheel 164 includes a grinding wheel base 165 and a plurality of grinding tools 166 in a generally cuboid shape, which are arranged in a ring on the bottom surface of the grinding wheel base 165. The grinding tools 166 are formed, for example, by fixing abrasive grains with a prescribed adhesive. In this embodiment, the grinding wheel 164 is a segmented grinding wheel with a prescribed gap between the grinding tools 166, but it may also be a grinding wheel with a continuous arrangement of grinding tools forming a ring.

[0037] Inside the rotating shaft 160, a flow path (not shown) that serves as a channel for the grinding fluid is formed along the axial direction (Z-axis direction) of the rotating shaft 160. This flow path opens on the bottom surface of the grinding wheel base 165 via the mounting base 163 in a manner that allows the grinding fluid to be sprayed toward the grinding wheel 166.

[0038] Near the grinding wheel 164, which descends to a height position when grinding the wafer 80, a thickness measuring unit 54 is provided, for example, to measure the thickness of the wafer 80 in contact during the grinding process.

[0039] The grinding apparatus 1 includes the chuck table 3 of the present invention. Hereinafter, the chuck table 3 will be referred to as the chuck table 3 of Embodiment 1. Then, using...Figure 2 The exploded 3D view shows the grinding process used for wafer 80. Figure 1 The structure of the chuck worktable 3 shown will be explained.

[0040] The chuck worktable 3 has a plate-shaped perforated portion 30 and a frame 31 that exposes the retaining surface 302 of the perforated portion 30 and houses the perforated portion 30.

[0041] The porous portion 30 is formed, for example, of porous ceramics, porous metals, porous polytetrafluoroethylene, or porous carbon, and its shape is obtained by partially cutting the outer periphery of a circular porous plate in a straight line parallel to the tangent direction of the outer periphery. Then, the upper surface of the porous portion 30, that is, the exposed surface exposed from the frame 31, becomes the holding surface 302. The holding surface 302 is formed with a shape similar to the grinding surface 802 of the wafer 80 having the orientation plane 805, that is, for example, with the same shape as the wafer 80 but slightly smaller (or slightly larger) than the wafer 80, and has a notch 303 corresponding to the orientation plane 805 cut out. Alternatively, for example, the upper surface of the porous portion 30, i.e. the exposed surface exposed from the frame 31, may become the holding surface 302. The holding surface 302 is formed in a shape similar to the grinding surface 802 of the wafer 80 having the orientation plane 805, and in particular, in such a way that it is formed in the same shape and the same size, i.e., identical, with a notch 303 cut out corresponding to the orientation plane 805.

[0042] Furthermore, the outer periphery of the retaining surface 302 is composed of an arc-shaped outer periphery 304 and a straight notch 303. In addition, through self-grinding, the retaining surface 302 becomes an extremely gentle conical slope with the center of the retaining surface 302 as the vertex, to a degree that is imperceptible to the naked eye.

[0043] The center 3022 of the retaining surface 302 is a point (center) on the retaining surface 302 that is equidistant from the arc-shaped outer periphery 304. That is, the center 3022 of the retaining surface 302 is the center of the circle assuming that no notch 303 is formed on the retaining surface 302 and the retaining surface 302 is a perfect circle.

[0044] The frame 31 is made of, for example, stainless steel alloy, aluminum alloy, titanium alloy, or ceramic, and has a frame base 311 with a top circular shape and an annular wall 312 erected at a predetermined height on the outer periphery of the upper surface of the frame base 311. Furthermore, the upper surface of the annular wall 312 serves as the upper surface of the frame 31.

[0045] The area inside the annular wall 312 becomes a recess 315 for receiving the porous portion 30. Moreover, the porous portion 30 can fit into the recess 315.

[0046] On the base 311 of the frame, a plurality of bolt insertion holes 3112 are formed through the thickness direction (Z-axis direction) at certain intervals in the circumferential direction. For example, eight are formed at 45-degree intervals.

[0047] The portion of the annular wall 312 of the frame 31 corresponding to the notch 303 of the porous portion 30 has a thicker wall than the other portions. Furthermore, regarding the upper surface of the portion of the frame 31 corresponding to the notch 303, a step is provided by cutting away a portion of the annular wall 312, resulting in an upper surface 314 corresponding to the notch and a stepped surface 316. The upper surface 314 corresponding to the notch is at the same height as the arc-shaped upper surface 313 corresponding to the arc-shaped outer periphery of the frame 31, and the stepped surface 316 is one step lower than the upper surface 314 corresponding to the notch.

[0048] like Figure 2 As shown, an annular suction groove 3154 centered on the center of the frame base 311 and a suction hole 3155 overlapping the center of the frame base 311 are formed on the bottom surface of the recess 315 of the frame 31. Furthermore, the suction groove formed in the recess 315 of the frame 31 is not limited to this embodiment; a connecting groove can also be formed, in which multiple concentric annular suction grooves 3154 centered on the center of the bottom surface of the recess 315 extend radially, connecting the suction grooves 3154 equally in the circumferential direction.

[0049] At the bottom of the annular suction groove 3154, suction holes 3157 are formed through the Z-axis, spaced evenly in the circumferential direction, connecting the suction groove 3154 to a suction source such as a vacuum generating device (not shown). Additionally, a suction hole 3155 formed through the center of the frame 31 also connects to a suction source (not shown).

[0050] exist Figure 2 The porous portion 30 shown is embedded in the recess 315 of the frame 31, and the two parts are bonded together by an adhesive (not shown) to form a... Figure 1 , 3 In the state shown for the chuck table 3, make it located in Figure 1 The threaded hole formed on the upper surface of the worktable base (not shown) in the base 10 of the grinding device 1 coincides with the bolt insertion hole 3112, so that the fixing bolt through the bolt insertion hole 3112 is screwed into the threaded hole of the worktable base, thereby the chuck worktable 3 is fastened, thus becoming a state in which it is equipped in the grinding device 1.

[0051] like Figure 1 As shown, the chuck table 3 is connected to a chuck table rotation unit 52, which consists of a spindle and a motor, below the table base. The chuck table rotation unit 52 can rotate around the rotation axis in the Z-axis direction.

[0052] Furthermore, the chuck table 3 can, for example, adjust the inclination of the holding surface 302 relative to the lower surface of the grinding wheel 166 using a tilt adjustment unit (not shown). The tilt adjustment unit is provided, for example, at equal intervals along the circumferential direction on the bottom surface of the table base. That is, for example, two tilt adjustment units and a support column (not shown) for fixing the table base are arranged at 120-degree intervals along this circumferential direction. The two tilt adjustment units are, for example, electric cylinders, pneumatic cylinders, etc.

[0053] In the grinding apparatus 1, the chuck table 3 is surrounded by a cover 50, and can reciprocate along the Y-axis on the base 10 via a table moving unit (not shown) disposed below the cover 50 and the corrugated cover 500 connected to the cover 50. The table moving unit (not shown) is a ball screw mechanism or the like that that causes the electric slider to move linearly in the Y-axis direction.

[0054] exist Figure 1 In the grinding apparatus 1 shown, when grinding is performed while the wafer 80 is held by the chuck stage 3, the notch 303 formed on the holding surface 302 is aligned with the orientation plane 805 of the wafer 80, and the center of the wafer 80 coincides with the center 3022 of the holding surface 302 (the center 3022 of the arc-shaped outer periphery 304 of the holding surface 302). Furthermore, by adjusting the tilt of the chuck stage 3 using a tilt adjustment unit (not shown), the holding surface 302, which becomes an extremely gentle conical slope through self-grinding, is parallel to the lower surface of the grinding tool 166, i.e., the grinding surface. This ensures that the ground surface 802 of the wafer 80, held along the conical holding surface 302, is parallel to the grinding surface of the grinding tool 166. Furthermore, the table movement unit (not shown) moves the chuck table 3 along the +Y direction, and the chuck table 3 holding the wafer 80 causes the rotation center of the grinding wheel 164 of the grinding unit 16 to be offset by a predetermined distance in the horizontal direction relative to the center 3022 of the arc-shaped outer periphery 304 of the holding surface 302, i.e., the rotation center of the wafer 80, thereby... Figure 4 As shown, the wafer 80 is positioned via the rotation center of the rotating chuck table 3 by following the grinding wheel trajectory R1 of the rotating grinding wheel 166. Then, the wafer 80 is ground along the arc-shaped grinding wheel trajectory R1 from the center of the wafer 80 held on the holding surface 302 to its outer periphery, with the holding surface 302 conforming to the shape of the wafer 80. Furthermore, in Figure 4 In the example shown, the shape of the holding surface 302 is similar to that of the grinding surface 802 of the wafer 80. The holding surface 302 is slightly smaller than the grinding surface 802, but it can also be that the holding surface 302 has the same shape and size as the grinding surface 802 of the wafer 80, that is, they are identical.

[0055] In addition, in this embodiment, for example, Figure 1 The grinding wheel trajectory of the inner cutting edge on the inner circumference side of the grinding wheel 166 shown is set as follows: Figure 4 The mold trajectory R1 is shown.

[0056] In this embodiment 1 Figure 3 , 4 In the chuck table 3 shown, the chuck will be... Figure 4 The length of the grinding wheel trajectory R1 of the grinding wheel 166 on the holding surface 302 when the holding surface 302 has an arc-shaped outer periphery 304 is defined as length L1. The length of the grinding wheel trajectory R1 on the arc-shaped upper surface 313 of the frame 31 is defined as length L2. The length of the grinding wheel trajectory R1 on the upper surface of the wafer 80, indicated by the dashed line shown on the holding surface 302, i.e., the grinding surface 802, is defined as length Lw1. Then, the second ratio of length Lw1 to length (L1+L2) obtained by adding length L1 and length L2, = length Lw1 : length (L1+L2), is used to set... Figure 3 The wall thickness of the portion of the annular wall 312 of the frame 31 of the chuck worktable 3 shown corresponds to the notch 303 of the porous portion 30, that is, the notch of the corresponding portion corresponds to the inner periphery edge 3144 and the outer periphery edge 3145 of the upper surface 314.

[0057] That is, such as Figure 4 As shown, in the chuck table 3 of Embodiment 1, in the arc-shaped grinding wheel trajectory from the center of the grinding surface 802 of the wafer 80 (shown by the dashed line predetermined to be held by the holding surface 302) to the outer periphery, at one end 8051 of the orientation plane 805 of the wafer 80 predetermined to be held by the holding surface 302 (in... Figure 4 In the grinding wheel trajectory R2 (the end on the -X direction side), when the length of the grinding wheel trajectory R2 on the holding surface 302 is set to length L3, the length of the grinding wheel trajectory R2 on the upper surface of the frame 31 is set to L4, and the length of the grinding wheel trajectory R2 on the grinding surface 802 of the predetermined wafer 80 held by the holding surface 302 is set to length Lw2, at the outer peripheral position 3146 of the frame 31, the relationship of length Lw2:length (L3+L4) = length Lw1:length (L1+L2) holds true. At the other end 8052 of the orientation plane 805 of the wafer 80 predetermined to be held by the holding surface 302 (in Figure 4In the grinding wheel trajectory R3 (with the end in the +X direction), if the length of the grinding wheel trajectory R3 on the holding surface 302 is set to length L5, the length of the grinding wheel trajectory R3 on the upper surface of the frame 31 is set to L6, and the length of the grinding wheel trajectory R3 on the grinding surface 802 of the predetermined wafer 80 held by the holding surface 302 is set to length Lw3, then at the outer peripheral position 3147 of the frame 31, the relationship Lw3:length(L5+L6) = lengthLw1:length(L1+L2) holds. The straight line connecting the outer peripheral position 3146 and the outer peripheral position 3147 of the frame 31 is taken as the outer peripheral edge 3145 of the frame 31. For example, the width of the notch in the Y-axis direction corresponding to the upper surface 314 gradually decreases from the -X direction side to the +X direction side. That is, the inner periphery edge 3144 of the notch corresponding to the upper surface 314 is parallel to the straight notch 303 of the porous portion 30 fitted into the recess 315, but the outer periphery edge 3145 is not parallel to the notch 303.

[0058] To ensure that the grinding pressure applied to the wafer 80 does not increase in the grinding trajectory region passing through the orientation plane 805 of the wafer 80 compared to other cases, the inventors of this invention firstly... Figure 5 As shown, a chuck worktable 395 is manufactured as follows (i.e., a chuck worktable 395 as a stage prior to the improvement of the chuck worktable 3 of the present invention): In this chuck worktable 395, regarding the upper surface of the portion of the annular wall 312 of the frame 31 corresponding to the notch 303 of the porous portion 30, a step is provided by cutting off a portion of the annular wall 312, and a notch-corresponding upper surface 3958 having the same height as the arcuate upper surface 313 corresponding to the arcuate outer periphery of the frame 31, and a step surface one level lower than the notch-corresponding upper surface 3958. In this chuck worktable 395 in the experimental stage prior to the improvement, unlike the chuck worktable 3 of the present invention, the width of the notch-corresponding upper surface 3958 is constant, and this width is constant along the entire circumference of the upper surface of the frame 31. That is, in the experimental stage prior to the improvement of the chuck worktable 3 of the present invention, the chuck worktable 395 has a notch corresponding to the upper surface 3958, and the area ratio of the notch corresponding to the upper surface 3958 is... Figure 8 The upper surface of the frame 373 of the chuck stage 37 shown, corresponding to the notch 375 of the porous portion 370, is small. When the wafer 80, indicated by the dashed line, is held, the orientation plane 805 is parallel to the inner and outer periphery edges of the upper surface 3958 corresponding to the notch. Other structures are the same as the chuck stage 3 of the present invention.

[0059] Before the improvement Figure 5The height H of the retaining surface 3956 of the chuck table 395 after self-grinding, passing through the grinding wheel trajectory area of ​​the notch 303 (refer to...). Figure 6 )like Figure 6 As shown, it is lower than other areas. Figure 6 This relates to the chuck worktable 3 of the present invention, the chuck worktable 395 before improvement, and the... Figure 6 The chuck stage 37 shown is illustrated in top view, showing the corresponding portions of each frame relative to the orientation plane 805 of the wafer 80, and in front view, an explanatory diagram showing the height of each retaining surface after self-grinding. Additionally, in Figure 6 In, it is shown Figure 5 The cross-section along line b1-b2 of the chuck stage 395 shown is indicated by a double-dotted line, representing the outer periphery of the portion of the frame 31 of the chuck stage 395 corresponding to the orientation plane 805 of the wafer 80, as shown in top view. Figure 6 As shown, in the case of Figure 8 The chuck table 37 shown has undergone self-grinding of its retaining surface 372, through... Figure 8 The height H of the retaining surface 372 of the notch 375 shown is approximately constant, becoming a flat surface. Additionally, in Figure 6 In, it is shown Figure 8 The cross-section of the chuck stage 37 shown along line b1-b2 is indicated by dashed lines, representing the outer periphery of the portion of the frame 373 of the chuck stage 37 that corresponds to the orientation plane 805 of the wafer 80, as shown in top view.

[0060] Therefore, when this self-grinding... Figure 5 , Figure 6 When the wafer 80 held by the holding surface 3956 of the chuck stage 395 shown is ground, the portion of the wafer 80 corresponding to the orientation plane 805 is at a greater distance than... Figure 1 The grinding wheel 166 shown is ground in a lower state with its lower surface lower, therefore it is comparable to the grinding wheel used. Figure 8 Compared to the case of the chuck stage 37 shown, the amount by which the thickness of the portion of the ground wafer 80 corresponding to the orientation plane 805 is thinner than other portions can be reduced. That is, the flatness of the ground wafer 80 can be further improved. However, there is still a tendency for the thickness of the portion of the ground wafer 80 corresponding to the orientation plane 805 to be thinner than other portions.

[0061] That is, this is because, for example, as the length of multiple mold tracks R90 increases from... Figure 5As shown, the -X direction side towards the +X direction side becomes longer due to the constant width of the upper surface 3958 corresponding to the notch. The height H of the retaining surface 3956 in the grinding track area of ​​the notch 303 does not decrease sufficiently after grinding, and the portion of the retaining surface 3956 corresponding to the orientation plane 805 of the wafer 80 becomes flat midway from the -X direction side towards the +X direction side. This is considered to still result in a tendency for the thickness of the portion of the ground wafer 80 corresponding to the orientation plane 805 to be thinner than other portions (a tendency to be more easily cut).

[0062] In contrast, in the case of Figure 4 , Figure 6 In the chuck table 3 of this embodiment 1, after self-grinding, the height H of the retaining surface 302 passing through the grinding wheel trajectory area of ​​the notch 303 is as follows: Figure 6 As shown, it is lower than other areas. Additionally, Figure 6 It shows Figure 4 The cross-section along line b1-b2 of the chuck stage 3 is shown. Furthermore, the height H of the portion of the holding surface 302 corresponding to the orientation plane 805 of the wafer 80, passing through the die trajectory area of ​​the notch 303, is as follows: Figure 6 As shown in a manner that allows comparison with the self-grinding retaining surface 3956 of the chuck table 395, it is not flat midway from the -X direction side to the +X direction side. This is because, when passing through... Figure 4 One end 8051 of the orientation plane 805 of the predetermined wafer 80 held by the holding surface 302 shown (in) Figure 4 In the mold trajectory R2 (at one end of the -X direction), at the outer periphery position 3146 of the frame 31, the second ratio, i.e., the relationship of length Lw1:length(L1+L2) = length Lw2:length(L3+L4), holds true at the other end 8052 of the orientation plane 805 of the predetermined wafer 80 held by the holding surface 302. Figure 4 In the grinding wheel trajectory R3 (with one end in the +X direction), at the outer periphery position 3145 of the frame 31, the second ratio, i.e., the relationship of length Lw1:length(L1+L2) = length Lw3:length(L5+L6), holds. The straight line connecting the outer periphery positions 3146 and 3147 of the frame 31 is taken as the edge 3145 of the outer periphery of the frame 31. Moreover, when grinding the wafer 80 held on the holding surface 302 of the self-grinding chuck stage 3, the portion of the wafer 80 corresponding to the orientation plane 805 is relative to... Figure 1 The grinding wheel 166 shown is ground with its lower surface lowered, thus compared to using... Figure 8 The chuck worktable 37 shown is Figure 5Compared to the case of the chuck stage 395 shown, the thickness of the portion of the ground wafer 80 corresponding to the orientation plane 805 can be reduced by the amount of thickness that is thinner than other portions. That is, compared to the case of using the chuck stage 395, the flatness of the ground wafer 80 can be further improved.

[0063] As described above, the chuck stage 3 of this embodiment 1 has: a porous portion 30 having a holding surface 302; and a frame 31 that exposes the holding surface 302 and houses the porous portion 30. A second ratio is given to the length of the grinding wheel trajectory passing through the arc-shaped outer periphery 304 of the holding surface 302 on the upper surface of the predetermined wafer 80 held by the holding surface 302 (i.e., the grinding surface 802), and the length obtained by adding the length of the grinding wheel trajectory on the holding surface 302 (which is the upper surface of the chuck stage 3) and the length on the upper surface of the frame 31. This ratio is used to connect the... The outer periphery position 3146 of the frame 31 in the second ratio of the grinding track at one end 8051 of the orientation plane 805 of the pre-held wafer 80 and the outer periphery position 3147 of the frame 31 in the second ratio of the grinding track at the other end 8052 of the pre-held orientation plane 805 of the pre-held wafer 80 are used as the outer periphery edge 3145 of the frame 31. Therefore, even in the grinding track area through the orientation plane 805, the grinding pressure applied to the wafer 80 will not increase, and the ground wafer 80 can be made to have a uniform thickness.

[0064] Furthermore, in the chuck stage 3 of the present invention, for example, the radius of the arc-shaped outer periphery 304 of the holding surface 302 is set to 74 mm. Additionally, the radius of the arc-shaped outer periphery of the frame 31 is set to 84 mm, thereby setting the difference between the radius of the arc-shaped outer periphery of the frame 31 and the radius (74 mm) of the arc-shaped outer periphery 304 of the holding surface 302 to 10 mm. Furthermore, the radius of the wafer 80 is, for example, 75 mm.

[0065] The chuck worktable of the present invention is not limited to the chuck worktable 3 of Embodiment 1 described above, but may also be as described below. Figure 6 , Figure 7 The diagram shows a portion of the chuck worktable 38 of Embodiment 2, the chuck worktable 33 of Embodiment 3, and the chuck worktable 34 of Embodiment 4.

[0066] The differences between the chuck table 38 of Embodiment 2 and the chuck table 3 of Embodiment 1 will be described below. Furthermore, the structures other than those described below are the same in both the chuck table 3 of Embodiment 1 and the chuck table 38 of Embodiment 2. Figure 6 In the image, the notch of the chuck table 38 in Embodiment 2, which is different from the chuck table 3 in Embodiment 1, is shown in detail, with the edge 381 of the outer periphery of the upper surface 314 corresponding to the notch portion.

[0067] The chuck table 38 of embodiment 2 has a retaining surface 302, which is designed to interact with... Figure 4 The wafer 80, which has an orientation plane 805, is formed with a notch 303 corresponding to the orientation plane 805, so that the grinding surface is identical. The chuck table 38 is used for grinding operations such that the annular grinding wheel 166 can pass through the center 3022 of the arc-shaped outer periphery 304 of the holding surface 302, so that the center 3022 of the arc-shaped outer periphery 304 of the holding surface 302 is aligned with the center of the wafer 80, and the shape of the holding surface 302 is consistent with that of the wafer 80. The chuck stage 38, which grinds the wafer 80 along an arc-shaped grinding path from the center (i.e., from the center 3022 of the holding surface 302) of the wafer 80 held on the holding surface 302 to the outer periphery, has: a porous portion 30 having the holding surface 302; and a frame 31 that exposes the holding surface 302 and houses the porous portion 30. The frame 31 is formed in such a way that the ratio of the length of the grinding path on the holding surface 302 to its length on the upper surface of the frame 31 is uniform. More specifically, the frame 31 of the chuck stage 38 is formed as follows: Figure 4 The ratio of the length L1 of the mold trajectory R1 on the holding surface 302 to the length L2 on the arc-shaped upper surface 313 of the frame 31, as shown, is illustrated by, for example, through the straight notch 303. Figure 6 The ratio of the length L31 of the mold trajectory R32 on the holding surface 302 to the length L32 on the upper surface of the frame 31 (the notch corresponds to the upper surface 314), for example... Figure 6 The ratio of the length L33 of the mold trajectory R33 on the holding surface 302 to the length L34 on the corresponding upper surface 314 of the notch in the frame 31 is uniform. That is, Figure 4 The length L1 shown is: Figure 4 The relationship shown, where length L2 = length L31, length L32 = length L33, length L34 holds true.

[0068] In Embodiment 2, the width of the notch portion of the frame 31 of the chuck table 38 corresponding to the upper surface 314 in the Y-axis direction gradually decreases from the -X direction side towards the +X direction side. Furthermore, the outer periphery edge 381 of the notch portion of the frame 31 of the chuck table 38 corresponding to the upper surface 314 is as follows... Figure 6 , Figure 7 As shown, it approximates the outer periphery edge 3145 of the chuck worktable 3 in Embodiment 1. Furthermore, in Figure 7 In the middle, Figure 6 The area around line b2 is shown in magnification.

[0069] Furthermore, when grinding is performed on the chuck stage 38 of Embodiment 2, the wafer 80 held by the retaining surface 302 after self-grinding (for example, a wafer 80 having a ground surface 802 that is identical to the retaining surface 302) is roughly the same as in the case of the chuck stage 3 of Embodiment 1, the portion of the wafer 80 corresponding to the orientation plane 805 is more... Figure 1 The grinding wheel 166 shown is ground in a lower state, therefore, compared with the use of Figure 8 The chuck worktable 37 shown is Figure 5 Compared to the chuck stage 395 shown, the thickness of the portion of the ground wafer 80 corresponding to the orientation plane 805 can be reduced compared to other portions. That is, compared to the chuck stage 395, the flatness of the ground wafer 80 can be further improved.

[0070] Thus, in the chuck stage 38 of this embodiment 2, even in the grinding wheel trajectory area passing through the orientation plane 805, the grinding pressure applied to the wafer 80 will not increase, and the ground wafer 80 can be made to have a uniform thickness.

[0071] The differences between the chuck table 33 of Embodiment 3 and the chuck table 3 of Embodiment 1 will be described below. Furthermore, the structures other than those described below are the same in both the chuck table 3 of Embodiment 1 and the chuck table 33 of Embodiment 3. Figure 6 In the image, the notch portion of the chuck worktable 33 in Embodiment 3, which is different from the chuck worktable 3 in Embodiment 1, is shown in detail, with the edge 334 of the outer periphery of the upper surface 314 corresponding to the notch portion.

[0072] The chuck table 33 of embodiment 3 has a retaining surface 302, which is designed to interact with... Figure 4The wafer 80 shown, having an orientation plane 805, has a notch 303 formed on its grinding surface in a manner that corresponds to the orientation plane 805. The chuck table 33 is used for grinding operations in the following manner: the annular grinding wheel 166 can pass through the center 3022 of the arc-shaped outer periphery 304 of the holding surface 302, so that the center 3022 of the arc-shaped outer periphery 304 of the holding surface 302 is aligned with the center of the wafer 80, and the shape of the holding surface 302 is aligned with the shape of the wafer 80, at the center of the wafer 80 held on the holding surface 302 (i.e., from the center 3022 of the holding surface 302). The chuck stage 33 grinds the wafer 80 in an arc-shaped grinding path that reaches the outer periphery. The chuck stage 33 has: a porous portion 30 having a holding surface 302; and a frame 31 that exposes the holding surface 302 and houses the porous portion 30. The frame 31 is formed in a second ratio so that the length of the grinding path on the grinding surface 802 of the predetermined wafer 80 (e.g., a wafer 80 whose grinding surface 802 is congruent to the holding surface 302) held by the holding surface 302 is uniform with the length obtained by adding the length on the holding surface 302, which is the upper surface of the chuck stage 33, and the length on the upper surface of the frame 31.

[0073] In the chuck worktable 33 Figure 4 The second ratio of the length Lw1 of the grinding wheel trajectory R1 on the grinding surface 802 of the predetermined wafer 80 held by the holding surface 302 to the length L1 of the grinding wheel trajectory R1 on the holding surface 302 when passing through the arc-shaped outer periphery 304 of the holding surface 302 and the length L2 of the grinding wheel trajectory R1 on the arc-shaped upper surface 313 of the frame 31 is given by the length (L1+L2) = length Lw1 : length (L1+L2).

[0074] Furthermore, for example, through one end 3031 of the straight notch 303 Figure 3 The length Lw4 of the grinding wheel trajectory R35 shown is on the grinding surface 802 of the predetermined wafer 80 held by the holding surface 302. Figure 6 (Not shown in the diagram) The second ratio of the length (L38+L39) obtained by adding the length L38 of the mold trajectory R35 on the holding surface 302 and the length L39 on the upper surface of the frame 31 is = length Lw4 : length (L38+L39) = length Lw1 : length (L1+L2), and this relationship holds true, for example, through the straight notch 303. Figure 6 The grinding wheel trajectory R34 shown is of length Lw5 on the predetermined grinding surface 802 of the wafer 80 held by the holding surface 302. Figure 6(Not shown in the figure) The second ratio of the length (L35+L36) obtained by adding the length L35 of the mold trajectory R34 on the holding surface 302 and the length L36 on the upper surface of the frame 31 is given by the relationship Lw5: (L35+L36) = Lw1: (L1+L2).

[0075] In Embodiment 3, the width of the notch portion of the frame 31 of the chuck worktable 33 corresponding to the upper surface 314 in the Y-axis direction gradually decreases from the -X direction side towards the +X direction side. Furthermore, the outer periphery edge 334 of the notch portion of the frame 31 of the chuck worktable 33 corresponding to the upper surface 314 is as follows... Figure 1 , Figure 8 As shown, it is very similar to the outer periphery edge 3145 of the chuck worktable 3 in Embodiment 1.

[0076] When grinding is performed on the wafer 80 held on the retaining surface 302 after self-grinding of the chuck stage 38 in Embodiment 3, the situation is largely the same as that of the chuck stage 3 in Embodiment 1, and the portion corresponding to the orientation plane 805 of the wafer 80 is more... Figure 5 The grinding wheel 166 shown is ground in a lower state, therefore, compared with the use of ​ The chuck worktable 37 shown is ​ Compared to the chuck stage 395 shown, the thickness of the portion of the ground wafer 80 corresponding to the orientation plane 805 can be reduced compared to other portions. That is, compared to the chuck stage 395, the flatness of the ground wafer 80 can be further improved.

[0077] Thus, in the chuck stage 33 of this embodiment, even in the grinding wheel track area passing through the orientation plane 805, the grinding pressure applied to the wafer 80 will not increase, and the ground wafer 80 can be made to have a uniform thickness.

[0078] The differences between the chuck table 34 of Embodiment 4 and the chuck table 3 of Embodiment 1 will be described below. Furthermore, the structures other than those described below are the same in both the chuck table 3 of Embodiment 1 and the chuck table 34 of Embodiment 4. ​ In the image, the notch of the chuck table 34 in Embodiment 4, which differs from the chuck table 3 in Embodiment 1, is shown in detail, with the edge 346 of the outer periphery of the upper surface 314 corresponding to the notch portion.

[0079] The chuck table 34 of embodiment 4 has a retaining surface 302, which is configured to be in contact with... ​The wafer 80, which has an orientation plane 805, is formed with a notch 303 corresponding to the orientation plane 805, in a shape similar to the surface to be ground. The chuck table 34 is used for grinding as follows: the annular grinding wheel 166 can pass through the center 3022 of the arc-shaped outer periphery 304 of the holding surface 302, so that the center 3022 of the arc-shaped outer periphery 304 of the holding surface 302 is aligned with the center of the wafer 80, and the shape of the holding surface 302 is aligned with the shape of the wafer 80. Grinding is performed on the wafer 80 in an arc-shaped grinding wheel trajectory from the center of the wafer 80 held on the holding surface 302 to the outer periphery. The chuck worktable 34 has: a perforated portion 30 having a holding surface 302; and a frame 31 that exposes the holding surface 302 and houses the perforated portion 30. The ratio of the length of the die trajectory passing through the arc-shaped outer periphery 304 of the holding surface 302 on the holding surface 302 to the length on the upper surface of the frame 31 is used to form a straight line connecting the outer periphery position 3146 of the frame 31 where this ratio is true in the die trajectory passing through one end 3031 of the notch 303 and the outer periphery position 3147 of the frame 31 where this ratio is true in the die trajectory passing through the other end 3032 of the notch 303 as the edge 346 of the outer periphery of the frame 31.

[0080] Specifically, using ​ The ratio of the length L1 of the grinding wheel trajectory R1 of the grinding wheel 166 when maintaining the arc-shaped outer periphery 304 of the retaining surface 302 to the length L2 of the grinding wheel trajectory R1 on the arc-shaped upper surface 313 of the frame 31 is given by the ratio of length L1 to length L2. ​ The wall thickness of the portion of the perforated portion 30 of the annular wall 312 of the frame 31 of the chuck worktable 3 shown, corresponding to the notch portion 303, is set, that is, the inner periphery edge 3144 and the outer periphery edge 346 of the notch portion corresponding to the upper surface 314.

[0081] That is, such as ​ As shown, in the chuck worktable 34 of Embodiment 4, at one end 3031 of the straight notch 303 passing through the perforated portion 30 (in ​ In the mold trajectory R35 (at one end in the -X direction), at the outer periphery position 3148 of the frame 31, the relationship between the length L38 of the mold trajectory R35 on the holding surface 302 and the length L39 of the mold trajectory R2 on the upper surface of the frame 31, which is equal to the length L1 and length L2, holds true at the other end 3032 (passing through the notch 303). ​In the mold trajectory R38 (one end of the +X direction), at the outer periphery position 3149 of the frame 31, the length L40 of the mold trajectory R38 on the holding surface 302 is equal to the length L41 of the mold trajectory R38 on the upper surface of the frame 31. The relationship L1:L2 holds true. The straight line connecting the outer periphery position 3148 and the outer periphery position 3149 of the frame 31 is taken as the edge 346 of the outer periphery of the frame 31.

[0082] The width of the notch portion of the frame 31 of the chuck table 34 corresponding to the upper surface 314 in the Y-axis direction gradually decreases from the -X direction side to the +X direction side. Furthermore, the outer periphery edge 346 of the notch portion of the frame 31 of the chuck table 34 corresponding to the upper surface 314 is approximately the same as the outer periphery edge 3145 of the chuck table 3 in Embodiment 1, and very similar to the outer periphery edge 381 of the chuck table 38 in Embodiment 2.

[0083] When grinding is performed on the wafer 80 held on the retaining surface 302 after self-grinding of the chuck stage 34 in Embodiment 4, the situation is largely the same as that of the chuck stage 3 in Embodiment 1, the portion of the wafer 80 corresponding to the orientation plane 805 is more... ​ The grinding wheel 166 shown is ground in a lower state, therefore, compared with the use of ​ The chuck worktable 37 shown is ​ Compared to the chuck stage 395 shown, the thickness of the portion of the ground wafer 80 corresponding to the orientation plane 805 can be reduced compared to other portions. That is, compared to the chuck stage 395, the flatness of the ground wafer 80 can be further improved.

[0084] Thus, in the chuck stage 34 of this embodiment 4, even in the grinding wheel trajectory area passing through the orientation plane 805, the grinding pressure applied to the wafer 80 will not increase, and the ground wafer 80 can be made to have a uniform thickness.

[0085] The chuck table 3 of the present invention is not limited to the chuck table 3 of Embodiment 1, the chuck table 38 of Embodiment 2, the chuck table 33 of Embodiment 3, and the chuck table 34 of Embodiment 4, and can certainly be implemented in various different ways within the scope of its technical concept. Furthermore, the shapes of the various structures of the grinding apparatus 1 illustrated in the accompanying drawings are not limited thereto, and can be appropriately modified within the scope that enables the effects of the present invention to be achieved.

Claims

1. A chuck table having a holding surface formed with a linear notch portion cut out in correspondence with a directional plane of a wafer having an upper surface as a ground surface in a similar shape to the upper surface, for grinding processing in which a circular grinding tool is capable of passing through a center of a circular arc-shaped outer periphery of the holding surface, aligning the center of the circular arc-shaped outer periphery of the holding surface with a center of the wafer, and aligning the holding surface with a shape of the wafer, and grinding the wafer rotating about the center of the holding surface in a circular arc-shaped tool track from the center of the wafer held on the holding surface to the outer periphery, wherein the chuck table has: a porous portion having the holding surface; and a frame body housing the porous portion with the holding surface exposed, and the frame body is formed in a manner that a ratio of a length on the holding surface when the tool track passes through the circular arc-shaped outer periphery of the holding surface to a length on an upper surface of the frame body and a ratio of a length on the holding surface when the tool track passes through the linear notch portion of the holding surface to a length on the upper surface of the frame body are uniform.

2. The chuck table according to claim 1, wherein a straight line linking a position of the outer periphery of the frame body where the ratio is established in the tool track passing through one end side of the notch portion and a position of the outer periphery of the frame body where the ratio is established in the tool track passing through the other end side of the notch portion is set as an edge of the outer periphery of the frame body.

3. The chuck table according to claim 1 or 2, wherein the holding surface is the same shape and the same size as the upper surface of the wafer as the ground surface.

4. A chuck table having a holding surface formed with a linear notch portion cut out in correspondence with a directional plane of a wafer having an upper surface as a ground surface in a similar shape to the upper surface, for grinding processing in which a circular grinding tool is capable of passing through a center of a circular arc-shaped outer periphery of the holding surface, aligning the center of the circular arc-shaped outer periphery of the holding surface with a center of the wafer, and aligning the holding surface with a shape of the wafer, and grinding the wafer rotating about the center of the holding surface in a circular arc-shaped tool track from the center of the wafer held on the holding surface to the outer periphery, wherein the chuck table has: a porous portion having the holding surface; and a frame body housing the porous portion with the holding surface exposed, and the frame body is formed in a manner that a first ratio of a length when the tool track passes through a circular arc-shaped outer periphery of a predetermined wafer held by the holding surface other than the directional plane of the wafer to a length obtained by adding a length on the holding surface when the tool track passes through the circular arc-shaped outer periphery of the holding surface and a length on an upper surface of the frame body, and a second ratio of a length when the tool track passes through the directional plane of the predetermined wafer held by the holding surface to a length obtained by adding a length on the holding surface when the tool track passes through the linear notch portion of the holding surface and a length on the upper surface of the frame body are uniform.

5. The chuck table according to claim 4, wherein ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The frame is formed by connecting the outer peripheral position of the frame where the second ratio is established in the tool path on the one end side of the orientation plane of the predetermined wafer being held and the outer peripheral position of the frame where the second ratio is established in the tool path on the other end side of the orientation plane of the predetermined wafer being held.

6. The chuck table according to claim 4 or 5, wherein The holding surface and the upper surface of the wafer as the ground surface are the same shape and the same size.

Images