JP7471751B2 - Wafer Processing Method - Google Patents

Description

The present invention relates to a wafer processing method.

Semiconductor device chips such as ICs (Integrated Circuits) and LSIs (Large Scale Integration) are essential components in various electronic devices such as mobile phones and personal computers. Such chips are manufactured using disk-shaped wafers made of semiconductors such as silicon (Si), silicon carbide (SiC), and gallium arsenide (GaAs).

Disc-shaped wafers are generally cut from cylindrical ingots using a blade saw, wire saw, or the like. The shape of the wafer cut in this way often includes a curvature (warping) that extends over the entire surface. For this reason, wafers cut from ingots are often flattened to remove the warping before they are used to manufacture chips for semiconductor devices.

Wafers cut from an ingot are flattened, for example, by lapping. However, it is difficult to completely remove warping by lapping a wafer.

The wafer can also be flattened by grinding its surface. However, wafer grinding is generally performed while the wafer is held by suction on a chuck table.

When the wafer is sucked in this way, the shape of the wafer, including any inherent warpage, is corrected to a flat shape. For this reason, it is difficult to completely remove the warpage by grinding the wafer in this state, and the wafer that is separated from the chuck table often has a shape that retains some warpage.

As an effective method for removing warpage contained in the shape of a wafer, a method is known in which a cured ultraviolet-curable resin is applied to one side of the wafer and then the other side of the wafer is ground (see Patent Document 1). In this method, for example, the cured ultraviolet-curable resin is applied to one side of the wafer in the following order:

First, ultraviolet curing resin is applied to one side of the wafer. Next, the wafer is held on the holding surface of the stage so that the other side of the wafer on which the ultraviolet curing resin has been applied is exposed. Next, the wafer held on the holding surface of the stage is pressed from the other side of the wafer in a direction perpendicular to the holding surface of the stage by a pressing means. Next, after the pressing means is separated from the wafer, the ultraviolet curing resin is irradiated with ultraviolet light by an ultraviolet irradiation means to cure the ultraviolet curing resin.

According to this method, a hardened ultraviolet curing resin (protective member) is formed on one side of the wafer without pressure being applied to the wafer from the pressing means. In other words, the protective member is formed on one side of the wafer without causing internal stress that would significantly deform the wafer from its shape at the time it was cut from the ingot.

This method allows the wafer to be ground while it is held by suction on the chuck table via the protective member. In other words, the wafer can be ground to a shape close to the shape it had when it was cut from the ingot. This prevents the wafer from being warped when it is separated from the chuck table.

JP 2009-148866 A

In the above-mentioned method, in order to spread the UV-curable resin applied to one side of the wafer over the entire surface, the wafer held on the holding surface of the stage is pressed by a pressing means from the other side of the wafer in a direction perpendicular to the holding surface of the stage.

Here, the holding surface and the pressing surface of the pressing means that contacts the other surface of the wafer are not necessarily flat at the micron level, nor are they necessarily parallel to each other at the micron level. Furthermore, when the pressing means is separated from the wafer, the wafer attempts to restore itself to the shape it had when it was cut from the ingot, but since one surface of the wafer is coated with highly viscous ultraviolet-curing resin, it is highly likely that the wafer will not completely restore to its original shape.

Therefore, the ultraviolet curing resin can be cured in a state that reflects the flatness and parallelism of the holding surface of the stage and the pressing surface of the pressing means. In this case, there is a risk that the shape of the cured ultraviolet curing resin (protective member) will also be transferred to the shape of the wafer. As a result, the wafer may be deformed such that the amount of deformation changes from the center to the periphery, resulting in the formation of a concentric pattern on the wafer.

Due to these effects, the shape of the wafer when the protective member is formed on one side may change from the shape of the wafer when it is cut from the ingot. Therefore, even if the other side of the wafer is ground to make it appear flat, which may remove the warpage that occurs when the wafer is cut from the ingot, the effect on the shape of the wafer caused by the formation of the protective member may remain.

In view of the above, the object of the present invention is to provide a wafer processing method in which a protective member is provided on one side of a wafer and then the other side of the wafer is ground, and which is capable of flattening the wafer even if the shape of the wafer changes due to the formation of the protective member.

According to the present invention, a method for processing a wafer using a protective member forming device that forms a protective member by curing a liquid ultraviolet curing resin applied to the entire one side of the wafer, and a grinding device that holds the wafer via the protective member on the conical holding surface of a chuck table and grinds and flattens the other side of the wafer with a grinding wheel, the method comprising the steps of: a first measurement step of measuring the height of one or more points on the other side of the wafer with one side of the wafer in contact with the support surface using a height measuring device that includes a table having a support surface and a measuring unit that is capable of measuring the height from the support surface of the upper surface of a measurement object placed on the support surface and is capable of moving in a direction parallel to the support surface relative to the table; a protective member forming step of forming the protective member using the protective member forming device; and a step of measuring the height of the protective member with the protective member in contact with the support surface using the height measuring device. A wafer processing method is provided that includes a second measurement step of measuring the height of the other side of the wafer at a location corresponding to the location where the height was measured with the step; a change amount calculation step of calculating the amount of change in height of one or more locations on the other side of the wafer that has changed due to the formation of the protective member by referring to the height of one or more locations measured in the first measurement step and the height of the corresponding location measured in the second measurement step; and a grinding step of using the grinding device to grind the other side of the wafer with the grinding wheel by adjusting at least one of the inclination of the rotation axis of the holding surface and the inclination of the rotation axis of the grinding surface defined by the lower surface of the grinding wheel according to the amount of change in height of one or more locations on the other side of the wafer obtained in the change amount calculation step while holding the wafer via the protective member on the holding surface, so that the other side of the wafer becomes flat when the protective member is removed from one side of the wafer.

Preferably, after the grinding step, the method further includes a second grinding step in which one side of the wafer is ground with the grinding wheel using the grinding device while the other side of the wafer is held by the holding surface, and in the second grinding step, the wafer is ground with the grinding wheel by adjusting at least one of the inclination of the rotation axis of the holding surface and the inclination of the rotation axis of the grinding surface so that the generatrix of the holding surface closest to the grinding surface is parallel to the grinding surface.

Preferably, the method further includes a peeling step between the grinding step and the second grinding step, in which the protective member is peeled off from one side of the wafer.

Preferably, the locations at which the heights are measured in each of the first and second measurement steps include a location located at the center and a location located at the outer periphery of the other surface of the wafer.

Preferably, the grinding device includes a grinding unit to which a grinding wheel is attached, the grinding wheel having a grinding wheel and a ring-shaped wheel base on one side of which the grinding wheel is arranged in a ring shape, and the chuck table further includes a rotary drive source that rotates the holding surface around a straight line passing through the center of the holding surface as a rotation axis, and an inclination adjustment unit that adjusts the inclination of the rotation axis of the holding surface.

In the present invention, the other side of the wafer is ground by adjusting at least one of the inclination of the rotation axis of the holding surface of the chuck table and the inclination of the rotation axis of the grinding surface defined by the lower surface of the grinding wheel, depending on the amount of change obtained by calculating the height of the other side of the wafer before and after the protective member is formed.

This allows the other side of the wafer to be ground so as to offset the deformation of the wafer caused by forming the protective member. As a result, it is possible to provide a wafer whose other side is flat after the protective member is peeled off from one side.

FIG. 1 is a cross-sectional view that typically illustrates a wafer. FIG. 2 is a perspective view that illustrates a protective member forming apparatus. FIG. 3 is a perspective view showing a schematic diagram of the grinding device. FIG. 4 is a partial cross-sectional side view that shows a schematic view of some of the components of the grinding device. FIG. 5 is a flow chart that illustrates an example of a wafer processing method. FIG. 6 is a perspective view that illustrates a height measuring device. FIG. 7 is a perspective view that shows a schematic of a wafer and some of the components of a height gauge when measuring the height of one or more locations on the other surface of the wafer. FIG. 8 is a partial cross-sectional side view that illustrates a wafer carried onto a stage. FIG. 9 is a partial cross-sectional side view that typically shows the ultraviolet curing resin dropped onto the stage and the wafer held by suction on the pressing plate. FIG. 10 is a partial cross-sectional side view that typically shows the ultraviolet curing resin spread out by the pressure plate and the wafer separated from the pressure plate. FIG. 11 is a partial cross-sectional side view that typically shows the cured ultraviolet curing resin (protective member) and the wafer. FIG. 12 is a partially sectional side view that shows a schematic view of the wafer and some of the components of the grinding device when the other surface of the wafer is ground. FIG. 13 is a top view that typically shows the chuck table of the grinding apparatus when grinding the other surface of the wafer. FIG. 14 is a flow chart that illustrates another example of a wafer processing method.

An embodiment of the present invention will be described with reference to the attached drawings. First, the wafer to be processed in the present invention will be described. Figure 1 is a schematic cross-sectional view of wafer 1, which is an example of such a wafer.

The wafer 1 is cut from a cylindrical ingot using a blade saw, a wire saw, or the like. This ingot is made of a semiconductor such as silicon (Si), silicon carbide (SiC), or gallium arsenide (GaAs), and has a diameter of, for example, 6 to 12 inches. Furthermore, the wafer 1 has a notch or orientation flat (orientation flat) formed therein to indicate the crystal orientation.

As shown in FIG. 1, the wafer 1 has a shape that includes a curvature (warping) over the entire wafer. The warping of the wafer 1 occurs due to the difference between the processing strain that occurs on one surface 1a and the processing strain that occurs on the other surface 1b when the wafer 1 is cut from an ingot using a blade saw, a wire saw, or the like.

Specifically, when the processing distortion occurring on one surface 1a is smaller than the processing distortion occurring on the other surface 1b, the wafer 1 is curved overall so that one surface 1a has an overall concave shape and the other surface 1b has an overall convex shape, as shown in FIG. 1.

As the wafer 1 has a shape that includes warping, the height of each of the first surface 1a and the second surface 1b from a flat surface when the wafer 1 is placed on the flat surface varies from place to place. For example, the difference between the highest point and the lowest point on the first surface 1a or the second surface 1b of the wafer 1 is 10 to 20 μm.

The above-mentioned wafer 1 is an example of a wafer to be processed in the present invention, and the wafer to be processed in the present invention is not limited to the wafer 1 shown in FIG. 1.

Next, a protective member forming device used to form a protective member on one side 1a of the wafer 1 will be described. Figure 2 is a perspective view that shows a schematic diagram of a protective member forming device 2, which is an example of such a protective member forming device.

The protective member forming device 2 has a rectangular parallelepiped base 4 with an internal space. A stage 6 with a generally flat upper surface is arranged on top of the base 4 so as to close the internal space. The stage 6 is made of a material that transmits ultraviolet light, such as borate glass, quartz glass, and translucent alumina.

A light source 8 that emits ultraviolet light is disposed below the stage 6. A shutter 10 that blocks the ultraviolet light from the light source 8 is provided between the stage 6 and the light source 8. In addition, a filter 12 is disposed above the shutter 10 to block light of wavelengths that are not necessary for curing the ultraviolet curable resin, for example.

When the shutter 10 is closed, the ultraviolet light from the light source 8 is blocked by the shutter 10 and does not reach the stage 6. On the other hand, when the shutter 10 is open, the ultraviolet light from the light source 8 passes through the filter 12 and the stage 6.

An exhaust pipe 14 connected to an exhaust pump (not shown) or the like is provided on the side wall of the base 4. In the protective member forming device 2, if the temperature of the internal space of the base 4 rises due to the emission of ultraviolet rays by the light source 8, the stage 6 may deform and the flatness of the upper surface (support surface) may decrease. Therefore, the internal space of the base 4 is exhausted through the exhaust pipe 14 to suppress the temperature rise in the internal space of the base 4.

A support structure 16 is provided adjacent to the stage 6. The support structure 16 includes a pillar portion 16a extending upward from the base 4, and a eaves portion 16b extending horizontally from the upper end of the pillar portion 16a. A pressing mechanism 18 is provided in the center of the eaves portion 16b.

The pressing mechanism 18 includes a main rod 20 that is provided by penetrating the center of the eaves portion 16b so as to be perpendicular to the eaves portion 16b, and a plurality of secondary rods 22 that are provided by penetrating the eaves portion 16b generally parallel to the main rod 20. The multiple secondary rods 22 are arranged at approximately equal intervals so as to surround the main rod 20.

A disk-shaped pressure plate 24 is fixed to the lower end of the main rod 20 and the lower ends of the multiple secondary rods 22. Furthermore, a porous plate (not shown) with an exposed underside is provided below the pressure plate 24. This porous plate is connected to a suction source (not shown), and when the suction source is operated, negative pressure is generated on the underside (suction surface) of this porous plate.

Furthermore, each of the main rod 20 and the multiple secondary rods 22 is connected to a lifting mechanism (not shown) including a motor, etc. This lifting mechanism lowers the main rod 20 and the multiple secondary rods 22, thereby applying pressure to the object to be pressed that is placed between the stage 6 and the pressure plate 24. Note that this lifting mechanism can independently raise and lower the main rod 20 and the multiple secondary rods 22 to adjust the pressure applied to the object to be pressed.

In addition, the lifting mechanism can also raise the main rod 20 and the multiple sub-rods 22 while the object to be pressed is held by suction via a porous plate provided at the bottom of the pressing plate 24. This allows the object to be pressed to be moved upward from the stage 6.

In the protective member forming device 2 shown in FIG. 2, for example, a protective member that comes into contact with the underside of the pressed object is formed in the following order:

First, the object to be pressed is brought onto the stage 6. Next, the suction source connected to the porous plate is operated while the porous plate provided at the bottom of the pressing plate 24 is in contact with the object to be pressed. This causes the pressing plate 24 to suck and hold the object to be pressed via the porous plate.

Next, the pressure plate 24, which holds the object to be pressed by suction, is moved upward from the stage 6. Next, liquid ultraviolet curing resin is dripped onto the stage 6, and then the pressure plate 24 is lowered to spread the ultraviolet curing resin over the entire lower surface of the object to be pressed.

At this time, at least one of the following is set so that the thickness of the UV-curable resin becomes the desired thickness: the amount of descent of the pressing plate 24, the pressure applied to the object being pressed, the amount of UV-curable resin dripped onto the stage 6, and the type of resin. Next, the suction source connected to the porous plate is stopped. This separates the pressing plate 24 from the object being pressed.

Next, the pressing plate 24, which has been separated from the object to be pressed, is moved upward from the stage 6. Next, the shutter 10 is opened. Next, ultraviolet light is irradiated from the light source 8 through the filter 12 and the stage 6 onto the ultraviolet curing resin. This causes the ultraviolet curing resin present on the underside of the object to be pressed to harden.

As a result, a cured UV-curable resin (protective member) having a desired thickness is formed in contact with the lower surface of the pressed object. Note that the protective member forming device 2 described above is only one example of a protective member forming device that can be used in the present invention, and the protective member forming device that can be used in the present invention is not limited to the protective member forming device 2 shown in FIG. 2.

Next, a grinding device that holds the wafer 1 via a protective member and grinds and flattens the other surface 1b of the wafer 1 with a grinding wheel will be described. Figure 3 is a perspective view that shows a grinding device 30, which is an example of such a grinding device. Note that the X-axis direction, Y-axis direction, and Z-axis direction shown in Figure 1 are mutually orthogonal. The Z-axis direction can also be expressed as the vertical direction, the up-down direction, or the grinding feed direction.

The grinding device 30 has a base 32 on which each component is mounted. An opening 32a having a longitudinal portion along the X-axis direction is formed on the upper surface of the base 32. A ball screw-type X-axis direction movement mechanism 34 is disposed inside the opening 32a.

The X-axis direction movement mechanism 34 has a pair of guide rails (not shown) arranged along the X-axis direction. A ball screw (not shown) is arranged between the pair of guide rails along the X-axis direction. A pulse motor (not shown) for rotating the ball screw is connected to one end of the ball screw.

The ball screw is rotatably connected to a nut portion (not shown) provided on the underside of the X-axis moving table (not shown). When the ball screw is rotated by a pulse motor, the X-axis moving table moves along the X-axis direction.

A table cover 34a is provided on the X-axis moving table. A chuck table 36 is also provided on the table cover 34a. The chuck table 36 and other components will now be described with reference to FIG. 4. FIG. 4 is a partially cross-sectional side view that shows a schematic representation of some of the components of the grinding device 30, such as the chuck table 36.

The chuck table 36 has a disk-shaped frame 38 made of ceramics. The frame 38 has an annular side wall that defines a recess. A suction passage (not shown) is formed at the bottom of the recess. One end of the suction passage is exposed at the bottom surface of the recess, and the other end of the suction passage is connected to a suction source (not shown) such as an ejector.

A porous plate 40 is fixed in the recess of the frame 38. The bottom surface of the porous plate 40 is generally flat, but the back surface is a conical surface with the central portion protruding slightly compared to the outer periphery. When the suction source is operated, negative pressure is generated on the conical surface 40a of the porous plate 40 (the holding surface of the chuck table 36).

The upper part of a cylindrical spindle 42 is connected to the lower part of the chuck table 36. The spindle 42 has a rotation drive source (not shown) such as a servo motor. When this rotation drive source is operated, the chuck table 36 rotates around a rotation axis 44 that passes through the center of the holding surface 40a.

Below the chuck table 36, an annular bearing 46 is provided to support the chuck table 36 in a rotatable manner. Below the bearing 46, an annular support plate 48 is fixed. Below the support plate 48, an annular table base 50 is provided. The spindle 42 is located in the central opening of the annular bearing 46, the central opening of the annular support plate 48, and the central opening of the annular table base 50.

A load detection unit 52 is disposed between the lower surface of the support plate 48 and the upper surface of the table base 50. The load detection unit 52 has three load measuring devices 52a. The three load measuring devices 52a are spaced apart from one another along the circumferential direction of the upper surface of the table base 50. The upper surfaces of the load measuring devices 52a are in contact with the lower surface of the support plate 48. The load measuring devices 52a are, for example, diaphragm-type load cells.

The load measuring device 52a may be a column-type load cell. The load cell includes a sensor that converts the load into an electrical signal. The load cell may have, for example, a piezoelectric sensor having a piezoelectric element, but may instead have a strain gauge sensor or a capacitance sensor.

The chuck table 36 is supported on the table base 50 via a bearing 46, a support plate 48, and a load detection unit 52. Therefore, when the holding surface 40a is pressed, the load (grinding load) applied to the table base 50 is measured by the load detection unit 52.

Three support mechanisms (fixed support mechanism 54a, first movable support mechanism 54b, and second movable support mechanism 54c) are provided on the underside of the table base 50, spaced apart from each other along the circumferential direction of the table base 50. Each support mechanism is disposed directly below the load measuring device 52a. In this specification, these three support mechanisms are collectively referred to as the tilt adjustment unit 54.

A part of the table base 50 is supported by a fixed support mechanism 54a. The fixed support mechanism 54a has a pillar (fixed shaft) of a predetermined length. The upper part of this pillar is fixed to an upper support body fixed to the underside of the table base 50, and the lower part of this pillar is fixed to the support base.

The other two parts of the table base 50 are supported by a first movable support mechanism 54b and a second movable support mechanism 54c. Each of the first movable support mechanism 54b and the second movable support mechanism 54c has a support (movable shaft) 56 with a male screw formed at the tip.

The tip (upper part) of the support 56 is rotatably connected to an upper support 58 fixed to the underside of the table base 50. More specifically, the upper support 58 is a metal columnar member such as a rod having a screw hole, and the male screw of the support 56 is rotatably connected to the screw hole of the upper support 58.

A ring-shaped bearing 60 having a predetermined outer diameter is fixed to the outer periphery of the support column 56 of the first movable support mechanism 54b and the second movable support mechanism 54c. A portion of the bearing 60 is supported by a stepped support plate 62. In other words, the first movable support mechanism 54b and the second movable support mechanism 54c are supported by the support plate 62.

A pulse motor 64 that rotates the support 56 is connected to the bottom of the support 56. By operating the pulse motor 64 to rotate the support 56 in one direction, the upper support 58 rises. By operating the pulse motor 64 to rotate the support 56 in the other direction, the upper support 58 descends. In this way, the upper support 58 rises and falls, thereby adjusting the inclination of the table base 50 (i.e., the chuck table 36).

Referring again to FIG. 3, other components of the grinding device 30 will be described. A bellows-shaped dustproof and drip-proof cover 66 that can expand and contract in the X-axis direction is provided in the opening 32a so as to sandwich the table cover 34a.

Near one end of the opening 32a, an operation panel 68 for inputting grinding conditions, etc. is provided. Near the other end of the opening 32a, a rectangular parallelepiped support structure 70 is provided, extending upward.

A Z-axis direction movement mechanism 72 is provided on the front side of the support structure 70 (i.e., the operation panel 68 side). The Z-axis direction movement mechanism 72 includes a pair of Z-axis guide rails 74 arranged along the Z-axis direction.

A Z-axis moving plate 76 is attached to the pair of Z-axis guide rails 74 in a manner that allows it to slide along the Z-axis direction. A nut portion (not shown) is provided on the rear side (back side) of the Z-axis moving plate 76.

A Z-axis ball screw 78 arranged along the Z-axis direction is rotatably connected to this nut portion. A Z-axis pulse motor 80 is connected to one end of the Z-axis ball screw 78 in the Z-axis direction.

When the Z-axis ball screw 78 is rotated by the Z-axis pulse motor 80, the Z-axis moving plate 76 moves in the Z-axis direction along the Z-axis guide rail 74. A support 82 is provided on the front side of the Z-axis moving plate 76.

The support 82 supports the grinding unit 84. The grinding unit 84 has a cylindrical spindle housing 86 fixed to the support 82. A part of a columnar spindle 88 aligned in the Z-axis direction is housed in the spindle housing 86 in a rotatable state.

A servo motor 90 for rotating the spindle 88 is connected to the upper end of the spindle 88. The lower end of the spindle 88 is exposed from the spindle housing 86, and the upper surface of a disk-shaped wheel mount 92 made of a metal material such as stainless steel is fixed to this lower end.

An annular grinding wheel 94 with a diameter roughly equal to that of the wheel mount 92 is attached to the underside of the wheel mount 92. As shown in FIG. 4, the grinding wheel 94 has an annular wheel base 96 made of a metal material such as stainless steel. A plurality of grinding stones 98 are discretely arranged on the underside of the wheel base 96 along the circumferential direction of the underside.

The lower surfaces of the multiple grinding wheels 98 are arranged at approximately the same height in the Z-axis direction, and the lower surfaces define a grinding surface 98a for grinding the workpiece. When the servo motor 90 operates to rotate the spindle 88, the grinding wheel 94 rotates about a rotation axis 100 that passes through the center of the grinding surface 98a.

In the grinding device 30 shown in Figures 3 and 4, the upper surface of the workpiece is ground in the following order, for example.

First, the workpiece is loaded onto the holding surface 40a of the chuck table 36. Next, the suction source connected to the porous plate 40 via the suction path is operated to suck and hold the workpiece via the porous plate 40. This causes the workpiece to deform slightly to fit the shape of the conical holding surface 40a of the chuck table 36.

Then, a servo motor (not shown) operates to rotate the spindle 42, thereby rotating the chuck table 36, and the servo motor 90 operates to rotate the spindle 88, thereby rotating the grinding wheel 94. Next, the Z-axis pulse motor 80 operates to rotate the Z-axis ball screw 78, thereby lowering the Z-axis moving plate 76.

As a result, the upper surface of the workpiece and the grinding wheel 98 come into contact while rotating together. As a result, the upper surface of the workpiece is ground. Note that the grinding device 30 described above is one example of a grinding device that can be used in the present invention, and the grinding device that can be used in the present invention is not limited to the grinding device 30 shown in Figures 3 and 4.

Next, a method for processing the wafer 1 will be described in which a protective member is formed on one side 1a of the wafer 1 using a protective member forming device 2, and then the other side 1b of the wafer 1 is ground using a grinding device 30. FIG. 5 is a flow chart that shows a schematic example of such a method for processing the wafer 1.

In this processing method, first, a height measuring device is used to measure the height of one or more locations on the other surface 1b of the wafer 1 (first measurement step: S1). The height measuring device used for this measurement may be either a contact height measuring device or a non-contact height measuring device.

However, when a contact-type height gauge is used, there is a risk that the height of the other side 1b of the wafer 1 may change due to the pressure applied when the height gauge comes into contact with the other side 1b of the wafer 1 during measurement. For this reason, a non-contact type height gauge is preferable as the height gauge used in the first measurement step (S1).

An example of a non-contact height measuring device is a measuring device that measures the surface height of an object by irradiating the object with a laser beam and detecting the laser beam reflected by the surface of the object.

Figure 6 is a perspective view showing a height measuring device 102, which is an example of a height measuring device used to measure the height of the other surface 1b of the wafer 1. Note that the A-axis direction and the B-axis direction shown in Figure 6 are perpendicular to each other.

The height measuring device 102 has a flat rectangular parallelepiped base 104. A sliding plate 106 is provided on the base 104. The sliding plate 106 has an A-axis sliding plate 106a provided on the base 104, and a B-axis sliding plate 106b provided on the A-axis sliding plate 106a.

The A-axis direction sliding plate 106a and the B-axis direction sliding plate 106b each have a flat rectangular parallelepiped shape. A cylindrical table 108 is provided on the center of the B-axis direction sliding plate 106b. The lower part of the table 108 is fixed to the upper part of the B-axis direction sliding plate 106b. In the height measuring device 102, the upper surface of the table 108 becomes the support surface 108a that supports the object to be measured.

Furthermore, the sliding plate 106 is connected to a sliding mechanism (not shown) including a motor, etc. By independently sliding the A-axis direction sliding plate 106a and the B-axis direction sliding plate 106b with this sliding mechanism, the table 108 can be moved to the desired coordinates in a coordinate system (AB coordinate plane) with the A-axis and B-axis as the coordinate axes.

A rectangular parallelepiped support structure 110 extending upward is connected to the side wall of the base 104. A support arm 112 extending along the A-axis direction is provided on the front side of the support structure 110 (i.e., the table 108 side). A measurement unit 114 is provided at the tip of the support arm 112.

The measurement unit 114 includes a laser oscillator (not shown) that irradiates a laser beam toward the upper surface (support surface) 108a of the table 108, and an optical sensor (not shown) that detects the laser beam reflected by the table 108. Furthermore, the height measuring device 102 includes a control unit (not shown) that controls the operation of each component.

The control unit controls the operation of the sliding mechanism connected to the sliding plate 106 and the irradiation of the laser beam from the measurement unit 114 so that the height of the object to be measured is measured at the target location. When the measurement unit 114 detects the laser beam reflected by the top surface of the object to be measured, the control unit calculates the height of the top surface of the object to be measured from the support surface 108a.

Figure 7 is a perspective view that shows a schematic view of some of the components of the wafer 1 and the height measuring device 102 when measuring the height of point 1b-1 on the other side 1b of the wafer 1. Note that point 1b-1 is a point located in the center of the other side 1b of the wafer 1.

When measuring the height of point 1b-1 using height measuring device 102, first, wafer 1 is placed on support surface 108a so that one surface 1a of wafer 1 is in contact with support surface 108a. Next, the control unit controls the operation of the sliding mechanism connected to sliding plate 106 to adjust the position of table 108 so that a laser beam is irradiated from measurement unit 114 to point 1b-1.

Then, the control unit controls the measurement unit 114 to irradiate the laser beam L1 from the measurement unit 114 toward the point 1b-1. Then, when the reflected laser beam L2 is detected by the measurement unit 114, the control unit calculates the height of the point 1b-1.

In the second height measurement (second measurement step: S3) described below, it is necessary to measure the height of the other surface 1b of the wafer 1 at a location corresponding to the location where the height was measured in this measurement (first measurement step: S1). Therefore, in the first measurement step, it is necessary to associate the coordinates in the AB coordinate plane with the location on the other surface 1b of the wafer 1 where the measurement was performed.

For example, with the notch 1c of the wafer 1 placed at a predetermined position on the support surface 108a, the control unit may store the coordinates in the AB coordinate plane corresponding to the location where the measurement was performed. Alternatively, the coordinates in the AB coordinate plane may be associated with the location on the other surface 1b of the wafer 1 where the measurement was performed by the following procedure.

First, the laser beam is scanned in a circular motion in an area slightly inside the outer periphery of the wafer 1. Next, since the measured height at the notch 1c is 0, the control unit stores the coordinates in the AB coordinate plane corresponding to the point where the height is 0. Next, the height of the other surface 1b of the wafer 1 is measured at an arbitrary point. Next, the control unit stores the coordinates in the AB coordinate plane corresponding to the point where the measurement was made.

This allows the relative positional relationship between the coordinates in the AB coordinate plane corresponding to the point where the height is 0 and the coordinates in the AB coordinate plane corresponding to the point on the other surface 1b of the wafer 1 where the measurement was performed to be determined. Then, in the second measurement step (S3), by similarly detecting the coordinates in the AB coordinate plane corresponding to the point where the notch 1c exists, the coordinates in the AB coordinate plane of the point where the height should be measured can be determined based on the relative positional relationship determined in the first measurement step (S1).

This measurement (first measurement step: S1) may also be performed at multiple locations on the other side 1b of the wafer 1. For example, this measurement may measure the heights of two locations: a location located in the center of the other side 1b of the wafer 1 and a location located in the outer periphery. Alternatively, this measurement may measure the heights of three locations: a location located in the center of the other side 1b of the wafer 1, a location located in the outer periphery, and a location located in the middle between the center and the outer periphery.

When the first measurement step (S1) is completed, a protective member is formed on one side 1a of the wafer 1 using the protective member forming device 2 shown in FIG. 2 (protective member forming step: S2). FIGS. 8 to 11 are schematic diagrams showing the process of forming a protective member on one side 1a of the wafer 1.

When forming a protective member on one side 1a of a wafer 1 using the protective member forming device 2, the wafer 1 is first loaded onto the stage 6 so that one side 1a of the wafer 1 faces downward. The wafer 1 is loaded onto the stage 6, for example, while being placed on a film 3 that is transported from the left front side to the right rear side of the protective member forming device 2 shown in FIG. 2 (see FIG. 8).

Next, the pressure plate 24 is lowered so that the lower surface of the pressure plate 24 comes into contact with the other surface 1b of the wafer 1. Next, the wafer 1 is held by suction on the lower surface of the pressure plate 24. As described above, the wafer 1 is held by suction via a porous plate provided below the pressure plate 24. When the wafer 1 is held by suction on the pressure plate 24, the wafer 1 is corrected to a flat shape by the effect of the negative pressure generated on the lower surface of the porous plate.

Then, the pressure plate 24 holding the wafer 1 by suction is raised. Next, liquid ultraviolet curing resin 5 is dripped onto the film 3 remaining on the stage 6. Next, the pressure plate 24 is lowered (see FIG. 9). This brings one surface 1a of the wafer 1 into contact with the liquid ultraviolet curing resin 5, and the liquid ultraviolet curing resin 5 is spread between the upper surface of the film 3 and one surface 1a of the wafer 1.

Next, the wafer 1 is separated from the porous plate provided below the pressure plate 24. Specifically, the operation of the suction source connected to this porous plate is stopped. This causes the wafer 1 to return from its flat shape to a non-flat shape that includes warping. Next, the pressure plate 24 is raised (see FIG. 10).

Next, the shutter 10 (FIG. 2) is opened and ultraviolet light is emitted upward from the light source 8 (see FIG. 11). This causes ultraviolet light to be irradiated onto the ultraviolet curing resin 5 via the stage 6, etc., and a cured ultraviolet curing resin (protective member) 5' is formed on one side 1a of the wafer 1.

Here, the lower surface of the pressing plate 24 (the lower surface of the porous plate) that presses the wafer 1 and the upper surface of the stage 6 that supports the wafer 1 via the film 3 are not necessarily flat at the micron level, nor are they necessarily parallel to each other at the micron level. Furthermore, when the pressing plate 24 is separated from the wafer 1, the wafer 1 attempts to restore itself to the shape it had when it was cut from the ingot, but since one side 1a of the wafer 1 is adhered with highly viscous ultraviolet curing resin 5, it is highly likely that the wafer 1 will not completely restore to its original shape.

Therefore, the UV-curable resin 5 can be cured in a state that reflects the flatness and parallelism of the surfaces that contact the upper surface of the stage 6 and the lower surface of the pressure plate 24 (the lower surface of the porous plate). In this case, there is a risk that the shape of this cured UV-curable resin (protective member) 5' will also be transferred to the shape of the wafer 1.

As a result, by providing the protective member 5' on one surface 1a of the wafer 1, the wafer 1 may be deformed such that the amount of deformation changes from the center toward the periphery, forming a concentric pattern on the wafer 1. For example, when comparing the shape of the wafer 1 shown in FIG. 8 with the shape of the wafer 1 shown in FIG. 11, the warping of the latter shape appears to be less severe than that of the former shape.

Therefore, in order to calculate the amount of deformation of the wafer 1 caused by the provision of the protective member 5', after the protective member formation step (S2) is completed, the height of the portion corresponding to the portion whose height was measured in the first measurement step (S1) is measured again using the height measuring device 102 shown in FIG. 6 (second measurement step: S3). This measurement is performed, for example, in the following order.

First, the wafer 1 and protective member 5' are placed on the support surface 108a so that the protective member 5' contacts the support surface 108a. Next, the control unit of the height measuring device 102 controls the operation of the sliding mechanism connected to the sliding plate 106 to adjust the position of the table 108 so that the measuring unit 114 irradiates a laser beam onto a location corresponding to the location 1b-1 whose height was measured in the first measurement step (S1).

Specifically, in the second measurement step (S3), as described above, with the notch 1c of the wafer 1 positioned at a predetermined position on the support surface 108a, the table 108 is moved so that the laser beam is irradiated to the same coordinates in the AB coordinate plane as those at which the height was measured in the first measurement step (S1).

Alternatively, as described above, the table 108 is moved so that the relative positional relationship between the coordinates in the AB coordinate plane where the laser beam is irradiated and the coordinates in the AB coordinate plane of the notch 1c coincides with this relative positional relationship in the first measurement step (S1).

The control unit then controls the measurement unit 114 to irradiate a laser beam from the measurement unit 114 toward the corresponding location. When the reflected laser beam is detected by the measurement unit 114, the control unit calculates the height of the corresponding location.

If the heights of multiple locations on the other surface 1b of the wafer 1 are measured in the first measurement step (S1), the heights of the corresponding multiple locations are also measured in the second measurement step (S2).

When the second measurement step (S3) is completed, the amount of change in height of one or more locations on the other surface 1b of the wafer 1 that has changed due to the formation of the protective member 5' on one surface 1a of the wafer 1 is calculated (amount of change calculation step: S4). Specifically, the amount of change in height is calculated by referring to the height of one or more locations measured in the first measurement step (S1) and the height of the corresponding locations measured in the second measurement step (S3).

For example, assume that the protective member 5' is formed to have a thickness of 100 μm. If the height of point 1b-1 located in the center of the other surface 1b of the wafer 1, measured in the first measurement step (S1), is 1000 μm, the reference height of point 1b-1 is 1100 (= 100 + 1000) μm, which can increase or decrease depending on the change in the shape of the wafer 1 caused by the formation of the protective member 5'.

Specifically, if the height of the point corresponding to point 1b-1 measured in the second measurement step (S3) is lower than the reference height (for example, 1095 μm), a negative value (for example, -5 μm) is calculated as the amount of change in height of the center of the other side 1b of the wafer 1. Also, if the height of the point corresponding to point 1b-1 measured in the second measurement step (S3) is higher than the reference height (for example, 1103 μm), a positive value (for example, +3 μm) is calculated as the amount of change in height of the center of the other side 1b of the wafer 1.

When the change amount calculation step (S4) is completed, the inclination of the rotation axis 44 of the holding surface 40a of the chuck table 36 shown in FIG. 4 and/or the rotation axis 100 of the grinding surface 98a defined by the underside of the grinding wheel 98 is adjusted according to the change amount obtained in the change amount calculation step (S4), and the other surface 1b of the wafer 1 is ground (grinding step: S5).

Specifically, the inclination of the rotating shaft 44 and/or the rotating shaft 100 is adjusted so that if the amount of change in height is a negative value (for example, if the calculated amount of change in height is -5 μm), the amount of grinding at the location where the height is measured is increased, and if the amount of change in height is a positive value (for example, if the calculated amount of change in height is +3 μm), the amount of grinding at the location where the height is measured is decreased.

Figure 12 is a partial cross-sectional side view showing a schematic diagram of the wafer 1 and some of the components of the grinding device 30 when grinding the other side 1b of the wafer 1. When grinding the other side 1b of the wafer 1, as shown in Figure 12, the wafer 1 is suction-held on the holding surface 40a of the chuck table 36 via the protective member 5'. At this time, the wafer 1 and the protective member 5' are corrected to a shape with a slightly pointed center due to the influence of the negative pressure generated on the conical holding surface 40a.

In addition, at least one of the inclination of the rotation axis 44 of the holding surface 40a and the inclination of the rotation axis 100 of the grinding surface 98a is adjusted according to the amount of change obtained in the amount of change calculation step (S4). A specific example of such an adjustment will be described with reference to FIG. 13. FIG. 13 is a top view that shows a schematic diagram of the chuck table 36 of the grinding device 30 when grinding the other surface 1b of the wafer 1.

The holding surface 40a of the chuck table 36 is conical. In the grinding device 30, only a portion of the holding surface 40a of the chuck table 36 (the left portion of the holding surface 40a shown in FIG. 13) faces the grinding wheel 98.

Therefore, when the generating line included in the part of the holding surface 40a is parallel to the grinding surface 98a, this generating line becomes the part of the holding surface 40a closest to the grinding surface 98a. For example, when the generating line 40b shown by the thin dotted line in FIG. 13 is parallel to the grinding surface 98a, the generating line 40b becomes the part of the holding surface 40a closest to the grinding surface 98a.

The grinding wheels 98 are also arranged discretely along the circumferential direction of the underside of the wheel base 96. Therefore, when the generating line included in the part of the holding surface 40a is parallel to the grinding surface 98a, the part of the holding surface 40a located directly below the part where the grinding wheel 98 contacts the other surface 1b of the wafer 1 is an arc-shaped part that starts at one end of the generating line and ends at the other end.

For example, when the generating line 40b and the grinding surface 98a shown in Figures 12 and 13 are parallel, the arc-shaped portion 40c, which starts at one end of the generating line 40b located at the apex of the holding surface 40a and ends at the other end, is located directly below the portion where the grinding wheel 98 and the other surface 1b of the wafer 1 contact each other.

Here, if the amount of change in the center of the other surface 1b of the wafer 1 calculated in the change amount calculation step (S4) is a negative value (e.g., -5 μm), it is necessary to grind the center of the other surface 1b more than the other parts.

In this case, the center of the holding surface 40a is made relatively higher than the outer periphery of the holding surface. For example, the upper support 58 of the second movable support mechanism 54c is raised by operating the pulse motor 64 of the second movable support mechanism 54c to rotate the support 56 in one direction.

As a result, the inclination of the rotation axis 44 (FIG. 12) of the holding surface 40a changes so that one end of the generatrix 40b located at the apex of the holding surface 40a shown in FIG. 13 is closer to the grinding surface 98a than the other end. When the other surface 1b of the wafer 1 is ground in this state, the amount of grinding at the center of the other surface 1b of the wafer 1 is greater than the amount of grinding at the outer periphery.

In addition, if in the change amount calculation step (S4) the change amount in height of the central portion of the other surface 1b of the wafer 1 is 0 μm and the change amount in height of the peripheral portion is a negative value (e.g., −5 μm), then the peripheral portion of the other surface 1b needs to be ground more than the central portion.

In this case, the outer periphery of the holding surface 40a is made relatively higher than the center. For example, the upper support 58 of the second movable support mechanism 54c is lowered by operating the pulse motor 64 of the second movable support mechanism 54c to rotate the support 56 in the other direction.

As a result, the inclination of the rotation axis 44 (FIG. 12) of the holding surface 40a changes so that the other end of the generatrix 40b located on the outer periphery of the holding surface 40a shown in FIG. 13 is closer to the grinding surface 98a than the one end. When the other surface 1b of the wafer 1 is ground in this state, the amount of grinding at the outer periphery of the other surface 1b of the wafer 1 is greater than the amount of grinding at the center.

Also, if in the change amount calculation step (S4) the change amount in height of two points located in the center and outer periphery of the other side 1b of the wafer 1 is 0 μm, and the change amount in height of the point located in the intermediate portion between the center and outer periphery is a negative value (e.g., -5 μm), then the intermediate portion of the other side 1b needs to be ground more than the center and outer periphery.

In this case, the middle part of the holding surface 40a is made relatively higher than the central part and the outer periphery. For example, the pulse motors 64 of the first movable support mechanism 54b and the second movable support mechanism 54c are operated to rotate the support posts 56 in one direction, thereby raising the upper supports 58 of the first movable support mechanism 54b and the second movable support mechanism 54c to the same extent. This changes the inclination of the rotation axis 44 of the holding surface 40a so that half of the holding surface 40a shown in FIG. 13 (the lower half of the holding surface 40a shown in FIG. 14) is closer to the grinding surface 98a than the remaining half (the upper half of the holding surface 40a shown in FIG. 14).

The stepping motor 64 of the first movable support mechanism 54b is operated to rotate the support 56 in one direction, thereby lifting the upper support 58 of the first movable support mechanism 54b. This changes the inclination of the rotation axis 44 (FIG. 12) of the holding surface 40a so that a portion of the holding surface 40a shown in FIG. 13 (a sector-shaped portion of the holding surface 40a shown in FIG. 14 that overlaps with the first movable support mechanism 54b and has a central angle of 120° as the center of the arc) is closer to the grinding surface 98a than the other portions.

When the tilt adjustment unit 54 is used to control the tilt of the rotation axis 44 of the holding surface 40a, the amount of fluctuation in the area close to the outer periphery of the holding surface 40a is greater than the amount of fluctuation in the area close to the center. Therefore, when the other surface 1b of the wafer 1 is ground in this state, the amount of grinding in the middle part of the other surface 1b of the wafer 1 is greater than the amount of grinding in the center and outer edge.

In the grinding step (S5), the inclination of the rotation axis 44 of the holding surface 40a is adjusted according to the amount of change in height of one or more locations on the other surface 1b of the wafer 1 obtained in the change amount calculation step (S4).

This allows the other surface 1b of the wafer 1 to be ground so as to offset the effect on the shape of the wafer 1 caused by the formation of the protective member 5'. As a result, it is possible to provide a wafer 1 whose other surface 1b is flat after the protective member 5' is peeled off from one surface 1a.

In the above-mentioned grinding step (S5), an example was shown in which only the inclination of the rotation axis 44 of the holding surface 40a was adjusted to grind the other surface 1b of the wafer 1, but in the grinding step of the present invention, only the inclination of the rotation axis 100 of the grinding surface 98a may be adjusted to grind the other surface 1b of the wafer 1. Alternatively, in the grinding step of the present invention, both the inclination of the rotation axis 44 of the holding surface 40a and the inclination of the rotation axis 100 of the grinding surface 98a may be adjusted to grind the other surface 1b of the wafer 1.

Furthermore, in the present invention, after grinding the other surface 1b of the wafer 1, one surface 1a of the wafer 1 may be ground using a grinding device 30. Figure 14 is a flow chart that shows a schematic diagram of another example of such a method for processing the wafer 1.

In the processing method shown in FIG. 14, after the grinding step (S5), the protective member 5' is peeled off from one surface 1a of the wafer 1 (peeling step: S6). The method for peeling off the protective member 5' is not limited to a specific method. For example, the protective member 5' may be mechanically peeled off using some kind of peeling device after heating the protective member 5'. Alternatively, the protective member 5' may be chemically peeled off by dissolving the protective member 5' using some kind of solvent.

When the peeling step (S6) is completed, one side 1a of the wafer 1 is ground using the grinding device 30 (second grinding step: S7). This grinding is performed while the other side 1b of the wafer 1 is held by suction on the holding surface 40a of the chuck table 36.

As described above, the other surface 1b of the wafer 1 becomes flat after the protective member 5' is peeled off. Therefore, grinding of one surface 1a of the wafer 1 only needs to be performed so that the entire surface is ground evenly. Specifically, the inclination of the rotation axis 44 of the holding surface 40a is adjusted so that the generating line 40b of the holding surface 40a shown in FIG. 13 is parallel to the grinding surface 98a.

In the above-mentioned second grinding step (S7), an example was shown in which one side 1a of the wafer 1 was ground by adjusting only the inclination of the rotation axis 44 of the holding surface 40a, but in the second grinding step of the present invention, one side 1a of the wafer 1 may be ground by adjusting only the inclination of the rotation axis 100 of the grinding surface 98a. Alternatively, in the second grinding step of the present invention, one side 1b of the wafer 1 may be ground by adjusting both the inclination of the rotation axis 44 of the holding surface 40a and the inclination of the rotation axis 100 of the grinding surface 98a.

In addition, in the wafer processing method of the present invention, the above-mentioned peeling step (S6) may be omitted, and in the second grinding step (S7), the removal of the protective member 5' and the grinding of one surface 1a of the wafer 1 may be performed consecutively.

This is preferable because it simplifies the wafer processing method. However, in this case, the same type of grinding wheel 98 is used to remove the protective member 5' and grind the wafer 1. Therefore, there is a risk that the protective member 5' will be removed and the wafer 1 will be ground using a type of grinding wheel 98 that is not suitable for removing the protective member 5' or grinding the wafer 1.

On the other hand, when the peeling step (S6) and the second grinding step (S7) are performed separately, this is preferable in that the removal of the protective member 5' and the grinding of the wafer 1 can be performed using a method suitable for these steps.

In addition, the structures and methods of the above-described embodiments and variations can be modified as appropriate without departing from the scope of the present invention.

1: Wafer 1a: One side 1b: Other side 1b-1: Location 1c: Notch 3: Film 5: Ultraviolet curable resin 5': Protective member 2: Protective member forming device 4: Base 6: Stage 8: Light source 10: Shutter 12: Filter 14: Exhaust pipe 16: Support structure 16a: Column portion 16b: Eaves portion 18: Pressing mechanism 20: Main rod 22: Sub-rod 24: Pressing plate 30: Grinding device 32: Base 32a: Opening 34: X-axis direction moving mechanism 34a: Table cover 36: Chuck table 38: Frame body 40: Porous plate 40a: Holding surface 40b: Generator 40c: Arc-shaped portion 42: Spindle 44: Rotating shaft 46: Bearing 48: Support plate 50: Table base 52: Load detection unit 52a : Load measuring device 54 : Tilt adjustment unit 54a : Fixed support mechanism 54b : First movable support mechanism 54c : Second movable support mechanism 56 : Support column 58 : Upper support body 60 : Bearing 62 : Support plate 64 : Pulse motor 66 : Dust-proof/water-proof cover 68 : Operation panel 70 : Support structure 72 : Z-axis direction moving mechanism 74 : Z-axis guide rail 76 : Z-axis moving plate 78 : Z-axis ball screw 80 : Z-axis pulse motor 82 : Support 84 : Grinding unit 86 : Spindle housing 88 : Spindle 90 : Servo motor 92 : Wheel mount 94 : Grinding wheel 96 : Wheel base 98 : Grinding stone 98a : Grinding surface 100 : Rotating shaft 102 : Height measuring device 104 : Base 106 : Sliding plate 106a: A-axis direction sliding plate 106b: B-axis direction sliding plate 108 : Table 108a: Upper surface (support surface)
110: Support structure 112: Support arm 114: Measurement unit

Claims (5)

A wafer processing method using a protective member forming device that forms a protective member by curing a liquid ultraviolet curing resin provided on the entirety of one surface of a wafer, and a grinding device that holds the wafer via the protective member on a conical holding surface of a chuck table and grinds and flattens the other surface of the wafer with a grinding wheel, comprising:
a first measurement step of measuring the height of one or more points on one surface of the wafer while the other surface of the wafer is in contact with the support surface, using a height measuring device including a table having a support surface and a measurement unit capable of measuring the height from the support surface of an upper surface of an object to be measured placed on the support surface and capable of moving in a direction parallel to the support surface relative to the table;
a protective member forming step of forming the protective member using the protective member forming apparatus;
a second measuring step of measuring the height of the other surface of the wafer at a location corresponding to the location whose height was measured in the first measuring step, with the protective member in contact with the support surface, using the height measuring device;
a change amount calculation step of calculating an amount of change in height of one or more points on the other surface of the wafer that has changed due to the formation of the protective member, by referring to the height of one or more points measured in the first measurement step and the height of the corresponding points measured in the second measurement step;
a grinding step of using the grinding device to grind the other side of the wafer with the grinding wheel by adjusting at least one of an inclination of a rotation axis of the holding surface and an inclination of a rotation axis of the grinding surface defined by a lower surface of the grinding wheel in accordance with an amount of change in height of one or more locations on the other side of the wafer obtained in the amount of change calculation step while holding the wafer with the holding surface via the protective member, so that the other side of the wafer becomes flat when the protective member is removed from one side of the wafer;
A wafer processing method comprising the steps of: After the grinding step, the method further includes a second grinding step of grinding one surface of the wafer with the grinding wheel using the grinding device while holding the other surface of the wafer with the holding surface,
2. The method for processing a wafer according to claim 1, wherein in the second grinding step, grinding is performed with the grinding wheel by adjusting at least one of an inclination of a rotation axis of the holding surface and an inclination of a rotation axis of the grinding surface so that a generatrix of the holding surface closest to the grinding surface becomes parallel to the grinding surface. 3. The method for processing a wafer according to claim 2, further comprising a peeling step between the grinding step and the second grinding step, of peeling the protective member from one surface of the wafer. 4. The wafer processing method according to claim 1, wherein the locations whose heights are measured in the first measurement step and the second measurement step include a location located in the center and a location located in the outer periphery of the other surface of the wafer. The grinding device includes a grinding unit to which a grinding wheel is attached, the grinding wheel having a circular wheel base on one side of which the grinding wheel is disposed in an annular manner,
5. The wafer processing method according to claim 1, wherein the chuck table further comprises: a rotational drive source that rotates the holding surface about a rotation axis that is a straight line passing through the center of the holding surface; and an inclination adjustment unit that adjusts the inclination of the rotation axis of the holding surface.

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