JP2018069348A - Fairing method of chuck table - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fair a holding surface in high accuracy so as to become parallel to a surface of a recessed part of a wafer after grinding.SOLUTION: A fairing method includes a wheel preparation step of installing a grinding wheel for grinding a wafer and a fairing grinding wheel 23 equal in an outer diameter of a grinding grindstone 25 in a grinding unit 20, a recessed part grinding step of forming a circular recessed part 12 on a holding surface 11 by grinding the holding surface 11 of a chuck table 10 by positioning the fairing grinding wheel 23 and the chuck table 10 in the same position by a radial directional movement unit 40 when forming the circular recessed part by grinding the wafer and an annular inclined plane grinding step of forming an annular inclined plane 13 of an annular shape on the holding surface 11 by following after the circular recessed part 12 inclined toward the circular recessed part 12 by surrounding the circular recessed part 12 by grinding the periphery of the circular recessed part 12 by grinding-feeding while moving the fairing grinding wheel 23 in the radial direction before or after the recessed part grinding step.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a method for shaping a chuck table.

  As one of semiconductor wafer grinding methods, so-called TAIKO grinding is known which facilitates handling of ultra-thin wafers (see, for example, Patent Document 1). In this technique, only the portion of the back surface of the wafer corresponding to the lower side of the device region is ground to form a circular recess on the back surface of the wafer. Deflection of the wafer is corrected by the annular convex portion that remains without being ground on the outer periphery of the circular concave portion. Further, in this technique, the wafer is ground with a grinding wheel having an outer diameter on the outermost periphery of the rotation path of the grinding wheel (hereinafter simply referred to as “the outer diameter of the grinding wheel”) substantially equal to the radius of the circular recess of the wafer.

  By the way, when grinding a wafer, the rotation axis of the grinding wheel is set to the rotation axis of the chuck table in order to suppress the surface burn of the wafer and to prevent the formation of a damped grinding mark on the wafer. And tilted slightly. As a result, the circular concave portion of the wafer is ground relatively shallowly near the center and near the outer periphery, and is relatively deeply ground near the center in the radial direction. For this reason, if the holding surface of the chuck table that holds the wafer by suction is formed in a flat shape, the thickness of the circular concave portion of the wafer may be uneven.

  Therefore, in order to make the thickness of the circular concave portion of the wafer after grinding uniform, a technique for grinding and shaping the holding surface of the chuck table into a shape parallel to the surface of the circular concave portion of the wafer after grinding is known. (For example, refer to Patent Document 2).

Japanese Patent No. 5390740 JP 2008-060470 A

  However, the diameter of the chuck table is larger than the diameter of the circular recess of the wafer. For this reason, if a grinding wheel having the same diameter as the grinding wheel for wafer grinding is used and the grinding wheel is positioned at the same position as during wafer grinding and the chuck table holding surface is ground, An area that is not ground remains. On the other hand, if the holding surface is ground with a grinding wheel having a diameter larger than that of the grinding wheel for wafer grinding so that an unground area does not remain on the outer periphery of the holding surface, the holding surface is parallel to the surface of the circular recess of the wafer after grinding. It is difficult to shape the shape to become with high accuracy.

  The present invention has been made in view of the above, and an object of the present invention is to shape a chuck table that can shape the holding surface with high accuracy so as to be parallel to the surface of the circular concave portion of the wafer after grinding. It is to provide a method.

  In order to solve the above-mentioned problems and achieve the object, the chuck table shaping method of the present invention includes a rotatable chuck table having a holding surface and a region other than the outer peripheral edge of the wafer held by the chuck table. A grinding unit for grinding with a grinding wheel to form a circular recess on the back surface of the wafer, a grinding feed unit for relatively moving the grinding unit and the chuck table in a grinding feed direction perpendicular to the holding surface, and the grinding unit; A method of shaping the chuck table of a grinding apparatus, comprising: a radial movement unit that relatively moves the chuck table in a radial direction parallel to the holding surface, wherein the grinding wheel for grinding a wafer is annular Wheel preparation step for mounting the grinding wheel arranged and the shaping grinding wheel having the same outer diameter of the grinding wheel to the grinding unit The shaping grinding wheel and the chuck table are positioned by the radial moving unit at the same position as when the circular recess is formed by grinding the wafer, and the holding surface of the rotating chuck table is ground. A concave grinding step for forming a circular concave portion on the holding surface, and before or after the concave grinding step, the concave portion of the holding surface rotating by grinding and feeding while moving the shaping grinding wheel in the radial direction. And an annular inclined surface grinding step for forming an annular slope surface on the holding surface, which is circumferentially ground, surrounds the circular concave portion and is inclined toward the circular concave portion, and follows the circular concave portion, The circular recess to be ground in the recess grinding step is formed in a region corresponding to the circular recess formed in the wafer.

  According to the shaping method of the chuck table of the present invention, the holding surface can be shaped with high accuracy so as to be parallel to the surface of the concave portion of the wafer after grinding.

FIG. 1A is a side sectional view showing a configuration example of a grinding apparatus used in the chuck table shaping method according to the embodiment. FIG. 1B is a side view showing a configuration example of a grinding apparatus used in the chuck table shaping method according to the embodiment. FIG. 1C is a plan view illustrating a configuration example of a grinding apparatus used in the chuck table shaping method according to the embodiment. FIG. 2A is a perspective view showing the surface of the wafer. FIG. 2B is a perspective view showing the back surface of the wafer. FIG. 3A is a cross-sectional side view showing a recess grinding step of the chuck table shaping method according to the embodiment, and shows a state before grinding. FIG. 3B is a cross-sectional side view showing the concave grinding step of the chuck table shaping method according to the embodiment, and shows a state during grinding. FIG. 4 is a cross-sectional side view showing an annular inclined surface grinding step of the chuck table shaping method according to the embodiment, and is a diagram showing a state during grinding. FIG. 5 is a cross-sectional side view of the wafer during grinding.

  Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. The present invention is not limited by the contents described in the following embodiments. The constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the structures described below can be combined as appropriate. Various omissions, substitutions, or changes in the configuration can be made without departing from the scope of the present invention.

  FIG. 1A is a side sectional view showing a configuration example of a grinding apparatus used in the chuck table shaping method according to the embodiment. FIG. 1B is a side view showing a configuration example of a grinding apparatus used in the chuck table shaping method according to the embodiment. FIG. 1C is a plan view illustrating a configuration example of a grinding apparatus used in the chuck table shaping method according to the embodiment. FIG. 2A is a perspective view showing the surface of the wafer. FIG. 2B is a perspective view showing the back surface of the wafer. FIG. 3A is a cross-sectional side view showing a recess grinding step of the chuck table shaping method according to the embodiment, and shows a state before grinding. FIG. 3B is a cross-sectional side view showing the concave grinding step of the chuck table shaping method according to the embodiment, and shows a state during grinding. FIG. 4 is a cross-sectional side view showing an annular inclined surface grinding step of the chuck table shaping method according to the embodiment, and is a diagram showing a state during grinding. FIG. 5 is a cross-sectional side view of the wafer during grinding.

  As shown in FIGS. 1A, 1B, and 1C, the chuck table shaping method according to the present embodiment shapes the holding surface 11 of the chuck table 10 by the grinding unit 20 of the grinding apparatus 1. The grinding apparatus 1 performs TAIKO grinding of the wafer W.

  The wafer W will be described with reference to FIGS. 2A and 2B. The wafer W is, for example, a disk-shaped semiconductor wafer or an optical device wafer whose base material is silicon, sapphire, gallium nitride (GaN), or the like. In the wafer W, for example, a plurality of regions are partitioned by division planned lines L called streets formed in a lattice pattern on the surface Wa. A device D is formed in these partitioned regions. The wafer W includes a device region W1 in which the device D is formed on the surface Wa, and an outer peripheral surplus region W2 that surrounds the device region W1. In the wafer W, a protective tape is attached to the surface Wa on which the device D is formed, and the back surface Wb on the back side of the surface Wa is ground. In the present embodiment, the wafer W is ground in a region overlapping the thickness direction corresponding to the device region W1 on the back surface Wb. In the wafer W, a region corresponding to the outer peripheral surplus region W2 on the back surface Wb remains in an annular shape without being ground.

  Returning to FIG. 1A, the grinding apparatus 1 relatively moves the rotatable chuck table 10 having the holding surface 11, the grinding unit 20, and the grinding unit 20 and the chuck table 10 in the grinding feed direction orthogonal to the holding surface 11. A grinding feed unit 30 to be moved, a radial movement unit 40 for relatively moving the grinding unit 20 and the chuck table 10 in a radial direction parallel to the holding surface 11, a height measurement unit 50, and a positioning unit 60.

  The chuck table 10 holds the wafer W. The chuck table 10 has a circular holding surface 11 as viewed in the Z direction. The holding surface 11 is disposed in parallel to the XY plane. The holding surface 11 is formed of a porous material having a large number of fine suction holes. The chuck table 10 sucks and holds the wafer W through the holding surface 11 by a vacuum chuck method. The chuck table 10 can be rotated about the rotation axis AX10 independently in one direction or both directions by a rotation driving mechanism.

  The grinding unit 20 grinds a region other than the outer peripheral edge of the wafer W held on the chuck table 10, in other words, a region corresponding to the device region W1, and forms a circular recess W3 on the back surface Wb of the wafer W. The grinding unit 20 grinds a region other than the outer peripheral edge of the holding surface 11 of the chuck table 10, in other words, a region corresponding to the circular concave portion W <b> 3 of the wafer W to form the circular concave portion 12 on the holding surface 11.

  The grinding unit 20 faces the chuck table 10. The grinding unit 20 is attached by a grinding feed unit 30 so as to be vertically movable. In other words, the grinding unit 20 can be ground and fed by being lifted and lowered by the grinding feed unit 30.

  The grinding unit 20 includes a spindle 21 and a wheel mount 22 disposed at the tip of the spindle 21. A grinding wheel 26 (see FIG. 5) for grinding the wafer W or a shaping grinding wheel 23 for grinding the holding surface 11 of the chuck table 10 is attached to the wheel mount 22. The grinding wheel 26 or the shaping grinding wheel 23 can be rotated around the rotation axis AX20 by a rotation drive mechanism.

  As shown in FIG. 1B, the rotation axis AX20 is inclined at an angle θ with respect to the Z axis in the XZ plane. In other words, the rotation axis AX20 is slightly inclined with respect to the rotation axis AX10 of the chuck table 10. The reason why the rotation axis AX20 is slightly tilted with respect to the Z-axis is to prevent the surface of the wafer W from being burnt or having a wrinkled shape when the wafer W is ground.

  Returning to FIG. 1A, the grinding feed unit 30 relatively moves the grinding unit 20 and the chuck table 10 in the grinding feed direction orthogonal to the holding surface 11. The grinding feed unit 30 changes the relative positional relationship between the grinding unit 20 and the chuck table 10. The grinding feed unit 30 includes, for example, a ball screw, a ball nut, a motor, and the like. The grinding feed unit 30 moves the grinding unit 20 in the −Z direction so that the shaping grinding wheel 23 approaches the holding surface 11 of the chuck table 10. The grinding feed unit 30 moves the grinding unit 20 in the + Z direction to separate the shaping grinding wheel 23 from the holding surface 11 of the chuck table 10.

  The radial movement unit 40 relatively moves the grinding unit 20 and the chuck table 10 in the radial direction parallel to the holding surface 11. The radial direction moving unit 40 changes the relative positional relationship between the grinding unit 20 and the chuck table 10. The radial direction moving unit 40 includes, for example, a ball screw, a ball nut, a motor, and the like. The radial direction moving unit 40 moves the grinding unit 20 in the + Y direction so that the rotation axis AX20 approaches the rotation axis AX10. The radial direction moving unit 40 moves the grinding unit 20 in the −Y direction to separate the rotation axis AX20 from the rotation axis AX10.

  The height measuring unit 50 detects the height of the holding surface 11 of the chuck table 10.

  The positioning unit 60 moves the height measuring unit 50 in the radial direction parallel to the holding surface 11 of the chuck table 10. In other words, the positioning unit 60 brings the height measuring unit 50 into and out of contact with the rotation axis AX20 of the grinding unit 20. The positioning unit 60 moves the height measurement unit 50 in the −Y direction to bring the height measurement unit 50 closer to the rotation axis AX20. The positioning unit 60 moves the height measurement unit 50 in the + Y direction to separate the height measurement unit 50 from the rotation axis AX20.

  The chuck table shaping method executes a wheel preparation step, a recess grinding step, and an annular inclined surface grinding step. The order in which the processing of the recess grinding step and the annular inclined surface grinding step is performed is not limited. In the present embodiment, the processing is executed in the order of the wheel preparation step, the recess grinding step, and the annular inclined surface grinding step.

  First, the wheel preparation step is executed. The wheel preparation step is a step of mounting the shaping grinding wheel 23 on the grinding unit 20.

  As shown in FIGS. 1A and 1B, in the wheel preparation step, a shaping grinding wheel 23 is attached to the tip of the spindle 21 of the grinding unit 20 via a wheel mount 22. The shaping grinding wheel 23 has a ring-shaped wheel base 24 and a plurality of chip-shaped grinding wheels 25 fixed in an annular shape to the free end of the wheel base 24. The shaping grinding wheel 23 is attached to the wheel mount 22 via the wheel base 24.

  The outer diameter R20 of the grinding wheel 25 is equal to the outer diameter of the grinding wheel 28 of the grinding wheel 26. The grinding wheel 25 grinds the region of the holding surface 11 corresponding to the device region W1 over the entire surface. As shown in FIG. 1C, the outer diameter R20 of the grinding wheel 25 is smaller than R10 / 2, where the inner diameter of the holding surface 11 is R10. The grinding wheel 25 is fixed to the lower surface of the wheel mount 22 via the wheel base 24. The grinding wheel 25 is a segmented grinding wheel having a rectangular cross section parallel to the rotation axis AX20.

  After executing the wheel preparation step, the recess grinding step is executed.

  The recess grinding step will be described with reference to FIGS. 3A and 3B. In the recess grinding step, the shaping grinding wheel 23 and the chuck table 10 are positioned at the same position as when the wafer W is ground to form the circular recess W3, and the holding surface 11 of the rotating chuck table 10 is ground and held. This is a step of forming a circular recess 12 in the surface 11. The circular recess 12 is formed in a region of the holding surface 11 corresponding to the circular recess W3 formed in the wafer W.

  In the recess grinding step, first, as shown in FIG. 3A, the grinding wheel 25 is placed on the holding surface 11 of the chuck table 10 corresponding to the device region W1 of the wafer W (hereinafter referred to as “a recess forming region of the holding surface 11”). Position it above. At this time, the grinding wheel 25 disposed on the outermost side in the radial direction of the wheel base 24 is positioned on the inner side in the radial direction from the outer peripheral edge of the recess forming region of the holding surface 11.

  Then, as shown in FIG. 3B, the grinding wheel 23 is rotated downward by the grinding feed unit 30 while rotating the shaping grinding wheel 23, and the grinding wheel 25 is pressed against the recess forming region of the holding surface 11. The chuck table 10 is driven to rotate, and the holding surface 11 also rotates. At this time, the height measuring unit 50 is positioned in the recessed portion forming region of the holding surface 11 by the positioning unit 60. The height measuring unit 50 detects the height of the recessed portion forming region of the holding surface 11. Based on the detection result of the height measuring unit 50, the grinding unit 20 is ground and fed downward until it is determined that the thickness of the recess forming region of the holding surface 11 has reached a predetermined grinding amount. Grind the forming area. When it is determined that the thickness of the recess forming region of the holding surface 11 has reached a predetermined grinding amount, the grinding feed downward of the grinding unit 20 is stopped. Thus, in the recess grinding step, the recess forming region of the holding surface 11 is ground, and the circular recess 12 is formed in the holding surface 11. At the end of the recess grinding step, the width of the boundary portion 15 is L1. The boundary portion 15 is formed in an annular shape that surrounds the circular concave portion 12 and the annular convex portion 14, in other words, the radially outer side of the circular concave portion 12. The boundary portion 15 is a portion that is not ground by the grinding wheel 25. The boundary portion 15 has the same thickness as the annular convex portion 14.

  Since the rotation axis AX20 is slightly inclined with respect to the Z axis, the grinding wheel 25 arranged on the shaping grinding wheel 23 that rotates about the rotation axis AX20 rotates in a plane inclined with respect to the XY plane. To do. For this reason, the depth to which the holding surface 11 is ground varies depending on the distance from the rotation axis AX20. Thus, when grinding the wafer W, the holding surface 11 of the chuck table 10 is moved in the −Z direction at a position where the wafer W is deeply ground so that the thickness of the circular recess W3 of the wafer W is uniformly ground. The holding surface 11 of the chuck table 10 is shaped high in the + Z direction at a position where the wafer W is ground to a low level. In other words, the holding surface 11 is shaped into a shape parallel to the surface of the circular recess W3 of the wafer W being ground.

  After executing the recess grinding step, an annular inclined surface grinding step is executed. In the annular inclined surface grinding step, the shaping grinding wheel 23 is used as in the concave grinding step.

  The annular inclined surface grinding step will be described with reference to FIG. In the annular inclined surface grinding step, the boundary 15 around the circular concave portion 12 of the holding surface 11 that rotates by moving while grinding the shaping grinding wheel 23 in the radial direction is ground, and the circular concave portion 12 is surrounded by the circular concave portion 12. In this step, an annular inclined surface 13, which is an annular slope surface following the circular recess 12 inclined toward 12, is formed on the holding surface 11.

  At the end of the recess grinding step, the holding surface 11 (hereinafter referred to as “holding surface 11”) of the chuck table 10 corresponding to the outer peripheral surplus area W2 of the wafer W from the position where the grinding feed downward of the grinding unit 20 is stopped. The convex portion forming area of the holding surface 11 is ground while being pressed against the convex portion forming area "). More specifically, while the shaping grinding wheel 23 is rotated, the shaping grinding wheel 23 is moved in the radial direction of the holding surface 11, in other words, in a direction in which the rotation axis AX20 is moved away from the rotation axis AX10, and the grinding feed is performed. The unit 30 is ground and fed upward.

  Then, the boundary portion 15 surrounding the circular concave portion 12 is ground, and the convex portion forming region of the holding surface 11 is ground so as to be inclined toward the circular concave portion 12 to become an annular slope surface following the circular concave portion 12. . When the lower end of the grinding wheel 25 comes out above the holding surface 11, the grinding feed speed upward of the grinding unit 20 is increased and the grinding table 20 is retracted from the chuck table 10 in the grinding feed direction.

  In this manner, in the annular inclined surface grinding step, the boundary portion 15 is ground so as to be inclined toward the circular recess 12 and become a slope surface following the circular recess 12. By the annular inclined surface grinding step, the holding surface 11 of the chuck table 10 forms an annular inclined surface 13 that surrounds the circular recessed portion 12 and has a slope surface that is continuous with the inclination of the circular recessed portion 12. The annular inclined surface 13 eliminates the step between the circular recess 12 and the annular inclined surface 13 and smoothly continues. At the end of the annular inclined surface grinding step, the width of the boundary 15 is L2 (<L1).

  The holding surface 11 of the chuck table 10 used when manufacturing the TAIKO wafer is shaped by executing the wheel preparation step, the concave portion grinding step, and the annular inclined surface grinding step. The holding surface 11 is formed in a shape parallel to the surface of the circular recess W3 of the wafer W after grinding.

  Next, a wafer grinding step that is performed following such a wheel preparation step, a recess grinding step, and an annular inclined surface grinding step will be described.

  First, prior to the wafer grinding step, a wheel replacement step and a wafer preparation step are executed.

  In the wheel replacement step, the grinding wheel 26 is attached to the spindle 21 of the grinding unit 20. More specifically, first, the shaping grinding wheel 23 attached to the tip of the spindle 21 via the wheel mount 22 is removed. Then, a grinding wheel 26 is attached to the tip of the spindle 21 via a wheel mount 22.

  The grinding wheel 28 is fixed to the lower surface of the wheel mount 22 via the wheel base 24. The grinding wheel 28 is a segmented wheel having a rectangular cross section parallel to the rotation axis AX20. The grinding wheel 28 grinds the entire back surface Wb of the wafer W corresponding to the device region W1. The outer diameter of the grinding wheel 28 is approximately half the diameter of the wafer W.

  The wafer preparation step is a step of placing the wafer W on the holding surface 11 of the chuck table 10. A protective tape T (see FIG. 5) is applied to the surface Wa of the wafer W on which the semiconductor device is formed. The protective tape T is stuck so that the surface on the adhesive layer side and the surface Wa of the wafer W face each other. The protective tape T may be heat-resistant depending on the subsequent process. Then, the wafer W to which the protective tape T is stuck is stored in a supply / collection cassette (not shown). Then, the wafer W is placed on the chuck table 10 of the grinding apparatus 1 with the back surface Wb facing upward by a transfer mechanism (not shown). Then, by operating a vacuum device (not shown) of the chuck table 10 on which the wafer W is placed, the front surface Wa of the wafer W is attracted and held on the holding surface 11 of the chuck table 10 with the back surface Wb facing upward.

  The wafer W sucked and held on the holding surface 11 is curved along the shape of the holding surface 11. The annular inclined surface 13 is formed, and the step with the circular recess 12 is eliminated, so that the wafer W is reliably held on the holding surface 11.

  After executing the wheel exchange step and the wafer preparation step, the wafer grinding step is executed.

  As shown in FIG. 5, in the wafer grinding step, the front surface Wa side of the wafer W is held on the chuck table 10, and the rear surface Wb of the wafer W corresponding to the device region W <b> 1 is formed using the grinding wheel 26 to form the annular convex portion W <b> 4. This is the step of grinding the concave shape. More specifically, the grinding wheel 28 is positioned on the back surface Wb of the wafer W corresponding to the device region W1. At this time, the grinding wheel 28 disposed on the outermost side in the radial direction of the wheel base 27 is positioned on the inner side in the radial direction from the outer peripheral edge of the wafer W. Then, the grinding wheel 26 is ground and fed downward by the grinding feed unit 30 while rotating the grinding wheel 26, and the grinding wheel 28 is pressed against the back surface Wb of the wafer W. When the chuck table 10 is driven to rotate, the wafer W held by suction also rotates. Then, until the thickness of the wafer W corresponding to the device region W1 reaches a predetermined thickness, the grinding unit 20 is ground and fed to grind the back surface Wb of the wafer W corresponding to the device region W1. When it is determined that the thickness of the wafer W corresponding to the device region W1 has reached a predetermined thickness based on the detection result of the height measurement unit 50, the grinding feed downward of the grinding unit 20 is stopped. In this way, in the grinding step, the wafer W is ground at the central portion, so that a circular recess W3 having an inner diameter smaller than the outer diameter of the wafer W is formed. In the wafer W, an annular convex portion W4 is formed on the outer peripheral portion remaining without being ground.

  Since the rotation axis AX20 is slightly inclined with respect to the Z axis, the grinding wheel 28 disposed on the grinding wheel 26 that rotates about the rotation axis AX20 rotates in a plane inclined with respect to the XY plane. For this reason, the depth at which the wafer W is ground varies depending on the distance from the rotation axis AX20. In the wafer grinding step, the wafer W is ground while being curved along the holding surface 11 formed in a shape parallel to the surface of the circular recess W3 of the ground wafer W. Thereby, the circular recessed part W3 of the wafer W after grinding becomes uniform thickness.

  As described above, according to the shaping method of the chuck table according to the present embodiment, the chuck table 10 is held by the shaping grinding wheel 23 in which the outer diameters of the grinding wheel 26 for forming the circular concave portion of the wafer W and the grinding wheel 25 are equal. Surface 11 is ground. Thereby, this embodiment can form the holding surface 11 in the shape parallel to the surface of the circular recessed part W3 of the wafer W after grinding. In this way, in the present embodiment, the shape of the holding surface 11 of the chuck table 10 can be shaped with high accuracy so that the thickness of the circular recess W3 of the wafer W can be made uniform.

  According to the present embodiment, the annular inclined surface 13 is shaped by using the same shaping grinding wheel 23 as in the concave grinding step and grinding the shaping grinding wheel 23 obliquely with respect to the axial direction. Thus, in the present embodiment, it is not necessary to replace the shaping grinding wheel 23 between the recess grinding step and the annular inclined surface grinding step. For this reason, this embodiment can reduce the grinding time required for shaping the holding surface 11 of the chuck table 10.

  According to the present embodiment, the annular inclined surface 13 that surrounds the circular concave portion 12 and is a slope surface that follows the circular concave portion 12 is formed. Thus, according to the present embodiment, the entire surface of the wafer W can be held without difficulty in the circular recess 12 and the annular protrusion 14 with the holding surface 11 having no step. More specifically, the step between the circular concave portion 12 and the annular convex portion 14 is eliminated by the annular inclined surface 13, so that, for example, the step between the circular concave portion 12 and the annular convex portion 14 comes into contact with the outer peripheral portion of the wafer W. It is possible to suppress an excessive stress from acting on the outer peripheral portion.

  The present invention is not limited to the above embodiment. That is, various modifications can be made without departing from the scope of the present invention. For example, in the annular inclined surface grinding step, at least a part of the boundary portion 15 may be ground to form the annular inclined surface 13 that is a slope surface following the annular circular concave portion 12, and the outer peripheral portion of the boundary portion 15 is ground. There may be a part left untouched.

  In the said embodiment, although demonstrated as what performs a process in order of a wheel preparation step, a recessed part grinding step, and an annular inclined surface grinding step, you may perform an annular inclined surface grinding step before a recessed part grinding step.

DESCRIPTION OF SYMBOLS 1 Grinding device 10 Chuck table 11 Holding surface 12 Circular recessed part 13 Annular inclined surface (slope surface)
14 annular projection 20 grinding unit 23 shaping grinding wheel 25 grinding wheel 30 grinding feed unit 40 radial movement unit 50 height measurement unit 60 positioning unit W wafer Wa surface Wb back surface W1 device region W2 outer peripheral surplus region W3 circular recess W4 annular Convex

Claims (1)

A rotatable chuck table having a holding surface, a grinding unit for grinding a region other than the outer peripheral edge of the wafer held by the chuck table with a grinding wheel to form a circular recess on the back surface of the wafer, the grinding unit and the grinding unit A grinding feed unit that relatively moves the chuck table in a grinding feed direction orthogonal to the holding surface; and a radial movement unit that relatively moves the grinding unit and the chuck table in a radial direction parallel to the holding surface. A method for shaping the chuck table of a grinding apparatus comprising:
A grinding wheel in which the grinding wheel for grinding a wafer is annularly arranged, and a wheel preparation step of mounting a shaping grinding wheel having the same outer diameter of the grinding wheel on the grinding unit;
The shaping grinding wheel and the chuck table are positioned by the radial movement unit at the same position as when the circular recess is formed by grinding the wafer, and the holding surface of the rotating chuck table is ground. A recess grinding step for forming a circular recess in the holding surface;
Before or after the concave grinding step, the periphery of the concave portion of the holding surface that is rotated by grinding and feeding while moving the shaping grinding wheel in the radial direction is ground, surrounding the circular concave portion, and the circular concave portion. An annular inclined surface grinding step that forms an annular slope surface on the holding surface that follows the circular recess,
Including
The method for shaping a chuck table, wherein the circular concave portion to be ground in the concave portion grinding step is formed in a region corresponding to the circular concave portion formed in the wafer.

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