JP7614711B2 - Method for processing workpiece - Google Patents

Description

The present invention relates to a method for processing a workpiece that is applied when grinding a disk-shaped workpiece such as a wafer.

In order to realize small and lightweight device chips, there are increasing opportunities to thin disk-shaped wafers with integrated circuits and other devices on the front side. For example, the front side of the wafer is held by a chuck table, and the chuck table and a grinding wheel with a grinding stone containing abrasive grains fixed to it are rotated relative to each other, and the grinding stone is pressed against the back side of the wafer while a liquid such as pure water is supplied, thereby grinding the wafer to make it thinner.

The outer edges of disk-shaped wafers used in the manufacture of device chips are usually chamfered to prevent chipping or cracking due to shocks applied during transportation. However, when a chamfered wafer is thinned by grinding or other methods, the outer edges of the wafer become sharp and brittle like a knife edge, making them more susceptible to chipping and cracking.

A technique called edge trimming has been proposed to remove the chamfered portion (hereinafter, the chamfered portion) of the wafer before grinding it (see, for example, Patent Document 1). For example, if a cutting blade is cut into the wafer to remove the chamfered portion, the outer edge will not become sharp and brittle even if the wafer is ground from the back side.

On the other hand, if edge trimming is used to completely remove the chamfered portion of the wafer, notches that indicate the wafer's orientation are lost, and differences in the wafer diameter are likely to occur. As a result, it becomes difficult to stack multiple wafers in the thickness direction and bond them together with high precision. Therefore, when combining this method with a technology such as Wafer On Wafer, which bonds multiple wafers together, only a portion of the front side of the chamfered portion is removed.

JP 2000-173961 A

However, when a wafer with part of the front side of the chamfer removed is ground from the back side, the part of the chamfer remaining on the outer edge (the part on the back side) tends to separate from the wafer and become a large scrap that tends to remain inside the equipment. This has led to an increase in the frequency of work required to remove the scrap.

The present invention was made in consideration of these problems, and its purpose is to provide a new method for processing a workpiece that can suppress the generation of large scraps when grinding a disk-shaped workpiece such as a wafer.

According to one aspect of the present invention, a method for processing a workpiece used in grinding a disk-shaped workpiece having a surface side including a device region, in which a device is provided in each of a plurality of regions partitioned by a planned division line, and an outer peripheral excess region surrounding the device region, includes a first holding step of holding the back side of the workpiece with a first chuck table, a first cutting step of cutting an annular region including the outer peripheral edge of the workpiece held by the first chuck table from the front side of the workpiece to a depth exceeding a depth corresponding to the finished thickness of the workpiece while rotating the first chuck table, thereby removing a portion of the front side of the annular region to form an annular remaining portion remaining on the back side, and a second cutting step of cutting the front side of the workpiece with a second chuck table. A method for processing a workpiece is provided, the method including: a second holding step of holding the workpiece on a chuck table; a second cutting step of removing the remaining portion by rotating the second chuck table while cutting the rotating second cutting blade into the workpiece held by the second chuck table from the back side of the workpiece to a position radially inward of the inner edge of the remaining portion and to a depth at which the remaining portion is removed; and a grinding step of grinding the workpiece from the back side to the finished thickness by rotating the second chuck table while contacting the workpiece held by the second chuck table with a grinding stone provided on a grinding wheel rotated about a rotation axis intersecting the rotation axis of the second cutting blade from the back side of the workpiece.

Preferably, the workpiece is ground from the back side in the grinding step while the remaining portion is removed in the second cutting step.

In a method for processing a workpiece according to one aspect of the present invention, a rotating first cutting blade is caused to cut into an annular region including the outer periphery of a workpiece held by a first chuck table from the front side of the workpiece to form an annular remaining portion that remains on the back side, and then, while held by a second chuck table used for grinding the workpiece, a rotating second cutting blade is caused to cut into the back side of the workpiece to remove the remaining portion, so that when the workpiece is ground, the remaining portion does not separate from the workpiece and become large scrap material.

In addition, in the method for processing a workpiece according to one aspect of the present invention, the rotating second cutting blade is caused to cut into the workpiece to a position radially inward of the inner edge of the remaining portion, so that the remaining portion can be reliably removed even in situations where it is difficult to improve the accuracy of cutting with the second cutting blade, such as when using a combined processing device that uses both a grinding wheel and a second cutting blade.

FIG. 1 is a perspective view showing a disk-shaped workpiece. FIG. 2 is a perspective view showing how an annular region including the outer periphery of a workpiece held by a chuck table of the cutting machine is machined. FIG. 3 is a cross-sectional view showing how an annular region including the outer periphery of a workpiece held by a chuck table of a cutting machine is machined. FIG. 4 is a perspective view showing how a cutting blade is cut into a workpiece held by a chuck table of a grinding device, and a grinding stone of a grinding wheel is brought into contact with the back surface of the workpiece. FIG. 5 is a cross-sectional view showing how a cutting blade is cut into a workpiece held by a chuck table of a grinding device, and a grinding stone of a grinding wheel is brought into contact with the back surface of the workpiece. FIG. 6 is a cross-sectional view showing the positional relationship between the cutting blade that cuts into the workpiece and the workpiece. FIG. 7 is a perspective view showing how the workpiece is thinned to the finished thickness. FIG. 8 is a cross-sectional view showing how the workpiece is thinned to its final thickness.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view showing a disk-shaped workpiece 11 to be processed by the method for processing a workpiece according to the present embodiment. As shown in FIG. 1, the workpiece 11 is, for example, a wafer formed into a disk shape using a semiconductor such as silicon (Si), and has a roughly circular front surface 11a and a roughly circular back surface 11b.

This workpiece 11 has been chamfered in advance. That is, the outer periphery (outer peripheral surface) 11c connecting the front surface 11a and the back surface 11b of the workpiece 11 is mainly composed of an outwardly convex curved surface. In addition, a part of the area including the outer periphery 11c of the workpiece 11 has a cutout portion 11d called a notch or the like that indicates the orientation of the workpiece 11 (typically, the crystal orientation).

The surface 11a of the workpiece 11 is divided into a central device region and a peripheral surplus region surrounding the device region. The device region is further divided into a number of small regions by a number of mutually intersecting division lines (streets) 13, and each small region is provided with a device 15 such as an IC (Integrated Circuit).

In this embodiment, a disk-shaped wafer made of a semiconductor such as silicon is used as the workpiece 11, but there are no limitations on the material, structure, size, etc. of this workpiece 11. For example, a substrate made of other materials such as semiconductors, ceramics, resins, metals, etc. can also be used as the workpiece 11. Similarly, there are no limitations on the type, number, shape, structure, size, arrangement, etc. of the devices 15.

In the method for processing a workpiece according to this embodiment, first, an annular region (chamfered portion) including the outer peripheral edge 11c of the workpiece 11 is partially removed from the front surface 11a side. Specifically, first, the back surface 11b side of the workpiece 11 is held by a chuck table (first chuck table) of a cutting device suitable for this processing (first holding step).

Figure 2 is a perspective view showing how an annular area including the outer peripheral edge 11c of the workpiece 11 held by the chuck table (first chuck table) 4 of the cutting device 2 is machined from the surface 11a side, and Figure 3 is a cross-sectional view showing how an annular area including the outer peripheral edge 11c of the workpiece 11 held by the chuck table 4 is machined from the surface 11a side.

As shown in Figures 2 and 3, the cutting device 2 is equipped with a chuck table 4 configured to hold a workpiece 11. The chuck table 4 includes a disk-shaped frame 6 formed from a metal such as stainless steel. A recess 6a having a circular opening at the upper end is formed on the upper surface side of the frame 6.

A holding plate 8 formed in a porous disk shape using ceramics or the like is fixed to the recess 6a of the frame 6. The upper surface 8a of the holding plate 8 is configured to be generally flat, and when the workpiece 11 is held by the chuck table 4, the back surface 11b of the workpiece 11 comes into contact with this upper surface 8a. Note that a protective member made of resin or the like may be attached in advance to the back surface 11b of the workpiece 11. In this case, the protective member comes into contact with the upper surface 8a of the holding plate 8.

The lower side of the holding plate 8 is connected to a suction source (not shown) such as an ejector via a flow path 6b provided inside the frame 6 and a valve (not shown). Therefore, when the back surface 11b of the workpiece 11 is brought into contact with the upper surface 8a of the holding plate 8, the valve is opened, and negative pressure from the suction source is applied, the workpiece 11 is held to the chuck table 4 by the suction force caused by the negative pressure.

A rotational drive source (not shown) such as a motor is connected to the lower part of the frame 6. The force generated by this rotational drive source causes the chuck table 4 to rotate, for example, around an axis (rotation axis) along the vertical direction (Z1 axis direction) so that the center of the upper surface 8a becomes the center of rotation. The frame 6 is also supported by a chuck table moving mechanism (not shown), and the chuck table 4 is moved by this chuck table moving mechanism in the processing feed direction (X1 axis direction) that is roughly parallel to the upper surface 8a.

A cutting unit (first cutting unit) 10 is disposed above the chuck table 4. The cutting unit 10 has a cylindrical spindle housing 12. A part of a columnar spindle 14 is housed in the space inside the spindle housing 12. The axis (rotation axis) of this spindle 14 is generally parallel to the upper surface 8a of the chuck table 4.

A cutting blade (first cutting blade) 16 with a cutting edge containing abrasive grains is attached to one end of the spindle 14 exposed from the spindle housing 12. A rotary drive source such as a motor (not shown) is connected to the other end of the spindle 14, and the cutting blade 16 attached to one end of the spindle 14 rotates around the axis of the spindle 14 by the force generated by this rotary drive source. A nozzle (not shown) is arranged next to the cutting blade 16 to supply a liquid (cutting fluid) such as water to the cutting blade 16 and the workpiece 11.

The spindle housing 12 (cutting unit 10) is supported, for example, by a cutting unit movement mechanism (not shown). The cutting unit 10 is moved by this cutting unit movement mechanism in an indexing feed direction (Y1 axis direction) that is generally parallel to the upper surface 8a of the chuck table 4 and generally perpendicular to the machining feed direction, and in a vertical direction that is generally perpendicular to the upper surface 8a.

When holding the back surface 11b of the workpiece 11 on the chuck table 4, the back surface 11b of the workpiece 11 is brought into contact with the top surface 8a, the valve is opened, and negative pressure from the suction source is applied. As a result, the workpiece 11 is held on the chuck table 4 by the suction force caused by the negative pressure, and the front surface 11a is exposed upward.

After the workpiece 11 is held by the chuck table 4, the cutting blade 16 is inserted into the annular area including the outer peripheral edge 11c of the workpiece 11, and a portion of the front surface 11a side is removed (first cutting step). Specifically, first, the position of the cutting unit 10 in the vertical direction is adjusted by the cutting unit movement mechanism so that the lower end of the cutting blade 16 is positioned at a height (position) between the front surface 11a and the back surface 11b of the workpiece 11.

Next, the cutting blade 16 is rotated to start supplying liquid from the nozzle. The relationship between the position of the chuck table 4 and the position of the cutting unit 10 in a direction generally parallel to the top surface 8a is adjusted by the chuck table movement mechanism and the cutting unit movement mechanism so that the cutting blade 16 cuts into the annular region including the outer periphery 11c. After that, the chuck table 4 is rotated one or more times around an axis along the vertical direction.

This allows the cutting blade 16 to cut along the outer peripheral edge 11c of the workpiece 11, removing a portion of the surface 11a side of the annular region including the outer peripheral edge 11c. That is, a side 11e that has a shape equivalent to the side of a cylinder and is generally perpendicular to the surface 11a is formed on the outer peripheral portion of the surface 11a side of the workpiece 11. Also, an annular remaining portion 11f consisting of another portion of the annular region remains on the back surface 11b side of the workpiece 11.

In this embodiment, the cutting blade 16 is cut into the workpiece 11 with the lower end of the cutting blade 16 positioned at a height (position) where the distance from the surface 11a side exceeds the finished thickness of the workpiece 11 (the thickness of the workpiece 11 after processing). In other words, the cutting blade 16 is cut from the surface 11a side of the workpiece 11 to a depth that exceeds the depth equivalent to the finished thickness of the workpiece 11. As a result, the height (vertical length) of the side surface 11e formed on the workpiece 11 becomes greater than the finished thickness of the workpiece 11.

After cutting the workpiece 11 with the cutting blade 16 to form the side surface 11e that is roughly perpendicular to the surface 11a and the annular remaining portion 11f, the workpiece 11 is ground from the back surface 11b side to thin it down to the finished thickness. Specifically, first, the surface 11a side of the workpiece 11 is held by the chuck table (second chuck table) of a grinding device (combined processing device) suitable for this processing (second holding step).

Figure 4 is an oblique view showing how the workpiece 11 held by the chuck table (second chuck table) 24 of the grinding device (combined processing device) 22 is processed from the back surface 11b side, and Figure 5 is a cross-sectional view showing how the workpiece 11 held by the chuck table 24 is processed from the back surface 11b side.

As shown in Figures 4 and 5, the grinding device 22 is equipped with a chuck table 24 configured to hold the workpiece 11. The structure of the chuck table 24 is similar to the structure of the chuck table 4 equipped in the cutting device 2. For example, the chuck table 24 includes a disk-shaped frame body 26 formed using ceramics or the like. A recess 26a having a circular opening at the upper end is formed on the upper surface side of the frame body 26.

A holding plate 28 formed in a porous disk shape using ceramics or the like is fixed to the recess 26a of the frame 26. The upper surface 28a of the holding plate 28 is configured in a shape corresponding to the side of a cone, and when the workpiece 11 is held by the chuck table 24, the surface 11a of the workpiece 11 comes into contact with this upper surface 28a.

In FIG. 5 and other figures, the upper surface 28a is depicted as flat, but the difference in height (height difference) between the center and the outer periphery of the upper surface 28a is approximately 10 μm to 30 μm. A protective member made of resin or the like may be attached in advance to the surface 11a of the workpiece 11. In this case, the protective member comes into contact with the upper surface 28a of the holding plate 28.

The lower side of the holding plate 28 is connected to a suction source (not shown) such as an ejector via a flow path 26b provided inside the frame 26, a valve (not shown), etc. Therefore, when the surface 11a of the workpiece 11 is brought into contact with the upper surface 28a of the holding plate 28, the valve is opened, and negative pressure from the suction source is applied, the workpiece 11 is held to the chuck table 24 by the suction force caused by the negative pressure.

A rotational drive source (not shown) such as a motor is connected to the lower part of the frame 26. The force generated by this rotational drive source rotates the chuck table 24 around an axis (rotation axis) parallel to the vertical direction (Z2 axis direction) or an axis (rotation axis) slightly tilted from the vertical direction, with the center of the upper surface 28a as the center of rotation. The frame 26 is also supported by a chuck table moving mechanism (not shown), and the chuck table 24 moves in the first horizontal direction (X2 axis direction) by this chuck table moving mechanism.

A grinding unit 30 is disposed above the chuck table 24. The grinding unit 30 includes, for example, a cylindrical spindle housing (not shown). A portion of a columnar spindle 32 is housed in the space inside the spindle housing. The axis (rotation axis) of the spindle 32 is, for example, parallel to the vertical direction or slightly inclined, and intersects with the upper surface 28a of the chuck table 24.

At the lower end of the spindle 32, for example, a disk-shaped mount 34 is provided. A plurality of holes (not shown) are formed on the outer periphery of the mount 34, penetrating the mount 34 in the thickness direction, and a bolt 36 or the like is inserted into each hole. A disk-shaped grinding wheel 38, which has roughly the same diameter as the mount 34, is fixed to the underside of the mount 34 by a bolt 36 or the like.

The grinding wheel 38 includes a disk-shaped wheel base 40 made of a metal such as stainless steel or aluminum. A plurality of grinding stones 42 are fixed to the underside of the wheel base 40 along the circumferential direction of the wheel base 40. A rotational drive source (not shown) such as a motor is connected to the upper end side of the spindle 32. The grinding wheel 38 rotates around the axis of the spindle 32 by the force generated by this rotational drive source.

A grinding nozzle (not shown) is provided next to or inside the grinding wheel 38, and is configured to supply a liquid (grinding fluid) such as water to the grinding stone 42 and the workpiece 11. The spindle housing of the grinding unit 30 is supported, for example, by a grinding unit movement mechanism (not shown). The grinding unit 30 moves vertically by this grinding unit movement mechanism.

A cutting unit (second cutting unit) 44 is disposed in a position that does not interfere with the grinding unit 30. The cutting unit 44 includes a cylindrical spindle housing 46. A portion of a columnar spindle 48 is housed in the space inside the spindle housing 46. The axis (rotation axis) of the spindle 48 intersects (e.g., perpendicular to) the axis of the spindle 32 included in the grinding unit 30.

A cutting blade (second cutting blade) 50 with a cutting edge containing abrasive grains is attached to one end of the spindle 48 exposed from the spindle housing 46. The width of this cutting blade 50 (cutting edge) is at least greater than the width (radial length) of the remaining portion 11f. A rotary drive source such as a motor (not shown) is connected to the other end of the spindle 48, and the cutting blade 50 attached to one end of the spindle 48 rotates around the axis of the spindle 48 by the force generated by this rotary drive source.

A cutting nozzle (not shown) is disposed next to the cutting blade 50, which can supply liquid (cutting fluid) such as water to the cutting blade 50 and the workpiece 11. The spindle housing 46 of the cutting unit 44 is supported, for example, by a cutting unit movement mechanism (not shown). The cutting unit 44 is moved by this cutting unit movement mechanism in a second horizontal direction (Y2 axis direction) that is approximately perpendicular to the first horizontal direction and vertical direction, and in the vertical direction.

When holding the front surface 11a of the workpiece 11 on the chuck table 24, the front surface 11a of the workpiece 11 is brought into contact with the upper surface 28a, the valve is opened, and negative pressure from the suction source is applied. As a result, the workpiece 11 is held on the chuck table 24 by the suction force caused by the negative pressure, and the back surface 11b is exposed upward.

After the workpiece 11 is held by the chuck table 24, the cutting blade 50 is cut into the workpiece 11 to remove the remaining portion 11f (second cutting step). In addition, the grinding stone 42 of the grinding wheel 38 is brought into contact with the back surface 11b side of the workpiece 11 to thin the workpiece 11 to the finished thickness (grinding step).

Specifically, first, the relationship between the positions of the chuck table 24, the grinding unit 30, and the cutting unit 44 is adjusted by the chuck table movement mechanism and the cutting unit movement mechanism so that the trajectory of the grinding stone 42 when rotating the grinding wheel 38 passes directly above the center of the workpiece 11 and the cutting blade 50 is positioned directly above the remaining portion 11f.

As shown in Figures 4 and 5, while the chuck table 24 is rotating, the cutting blade 50 is rotated and the cutting unit 44 is gradually lowered while liquid is supplied from the cutting nozzle. Similarly, while the chuck table 24 is rotating, the grinding wheel 38 is rotated and the grinding unit 30 is gradually lowered while liquid is supplied from the grinding nozzle. This allows the workpiece 11 to be ground from the back surface 11b side to make it thinner, while the cutting blade 50 cuts in to remove the remaining portion 11f.

Figure 6 is a cross-sectional view showing the positional relationship between the cutting blade 50 cutting into the workpiece 11 and the workpiece 11. As shown in Figure 6, in this embodiment, the relationship between the position of the chuck table 24 and the position of the cutting unit 44 is adjusted so that the cutting blade 50 cuts into the workpiece 11 to a position radially inward of the inner edge of the annular remaining portion 11f. In other words, the side of the cutting blade 50 located radially inward of the workpiece 11 is positioned radially inward of the side surface 11e.

In addition, in this embodiment, the cutting unit 44 is lowered so that the cutting blade 50 cuts to a depth that allows the annular remaining portion 11f to be completely removed. In other words, the cutting unit 44 is lowered until the height (position) of the bottom end of the cutting blade 50 is lower than the height (position) of the bottom end of the remaining portion 11f. However, the lowering of the cutting unit 44 must be stopped when the height (position) of the bottom end of the cutting blade 50 is higher than the height (position) of the back surface 11g of the workpiece 11 after grinding.

In this manner, in this embodiment, the cutting blade 50 is caused to cut into the workpiece 11 to a position radially inward of the inner edge of the annular remaining portion 11f, and the cutting blade 50 is caused to cut into the workpiece 11 so that the height (position) of the bottom end of the cutting blade 50 is lower than the height (position) of the bottom end of the remaining portion 11f and higher than the height (position) of the back surface 11g of the workpiece 11 after grinding. Therefore, even when using a grinding device 22 such as that of this embodiment, in which it is difficult to improve cutting accuracy, the remaining portion 11f of the workpiece 11 can be reliably removed.

In this embodiment, the grinding unit 30 and the cutting unit 44 are lowered so that the lower end of the cutting blade 50 descends before the lower end of the grinding wheel 42. In other words, the grinding unit 30 begins to descend after the cutting unit 44 begins to descend, and the grinding wheel 42 does not come into contact with the remaining portion 11f. In this way, the remaining portion 11f is removed by the cutting blade 50 without the grinding wheel 42 coming into contact with the remaining portion 11f, so that the remaining portion 11f does not separate from the workpiece 11 due to contact with the grinding wheel 42 and become a large scrap material.

Figure 7 is a perspective view showing how the workpiece 11 is thinned to the finished thickness, and Figure 8 is a cross-sectional view showing how the workpiece 11 is thinned to the finished thickness. As shown in Figures 7 and 8, when the remaining portion 11f is removed and the workpiece 11 is thinned to the finished thickness, the processing of the workpiece 11 is completed. When the workpiece 11 is thinned to the finished thickness, the back surface 11g after grinding is exposed upward.

As described above, in the method for processing the workpiece according to this embodiment, the rotating cutting blade (first cutting blade) 16 is cut into the annular region including the outer peripheral edge 11c of the workpiece 11 held by the chuck table (first chuck table) 4 of the cutting device 2 from the front surface 11a side of the workpiece 11 to form an annular remaining portion 11f remaining on the back surface 11b side. Then, while the workpiece 11 is held by the chuck table (second chuck table) 24 of the grinding device (combined processing device) 22 used for grinding the workpiece 11, the rotating cutting blade (second cutting blade) 50 is cut into the workpiece 11 from the back surface 11b side to remove the remaining portion 11f. Therefore, when the workpiece 11 is ground, the remaining portion 11f does not separate from the workpiece 11 and become a large scrap.

In addition, in the method for processing the workpiece according to this embodiment, the rotating cutting blade 50 is caused to cut into the workpiece 11 to a position radially inward from the inner edge of the remaining portion 11f, so that the remaining portion 11f can be reliably removed even in situations where it is difficult to improve the accuracy of cutting by the cutting blade 50, such as when using a grinding device 22 that uses both a grinding wheel 38 and a cutting blade 50.

Furthermore, in the method for processing the workpiece according to this embodiment, the workpiece 11 is ground from the back surface 11b side while the cutting blade 50 is cut in to remove the remaining portion 11f. This significantly shortens the time required to process the workpiece 11 compared to, for example, cutting in to completely remove the remaining portion 11f with the cutting blade 50 and then grinding the workpiece 11 from the back surface 11b side.

The present invention is not limited to the above-described embodiment, and can be modified in various ways. For example, after the remaining portion 11f is formed in the workpiece 11, any processing, including bonding the workpiece 11 to another workpiece, can be performed on the workpiece 11 before the workpiece 11 is held by the chuck table (second chuck table) 24.

In the above embodiment, the workpiece 11 is ground from the back surface 11b side while the cutting blade (second cutting blade) 50 is cut in to remove the residual portion 11f, but the workpiece 11 may be ground from the back surface 11b side after the cutting blade 50 is cut in to completely remove the residual portion 11f. In this case, the cutting blade 50 may be cut into the workpiece 11 and the residual portion 11f may be removed in the same procedure as when the residual portion 11f is formed.

In addition, in the above-described embodiment, the workpiece 11 is processed using the cutting device 2 and the grinding device (combined processing device) 22, but the workpiece 11 can also be processed in a similar manner using only the grinding device (combined processing device) 22. In this case, the cutting blade (first cutting blade) 50 is caused to cut into the workpiece 11 held by the chuck table (first chuck table) 24, thereby forming the remaining portion 11f.

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

11: Workpiece 11a: Surface 11b: Back surface 11c: Outer peripheral edge (outer peripheral surface)
11d: Notch portion 11e: Side surface 11f: Remaining portion 11g: Back surface 13: Planned division line (street)
15: Device 2: Cutting device 4: Chuck table (first chuck table)
6: Frame 6a: Recess 6b: Flow path 8: Holding plate 8a: Upper surface 10: Cutting unit (first cutting unit)
12: Spindle housing 14: Spindle 16: Cutting blade (first cutting blade)
22: Grinding equipment (complex processing equipment)
24: Chuck table (first chuck table, second chuck table)
26: Frame 26a: Recess 26b: Flow path 28: Holding plate 28a: Upper surface 30: Grinding unit 32: Spindle 34: Mount 36: Bolt 38: Grinding wheel 40: Wheel base 42: Grinding stone 44: Cutting unit (first 2 cutting units)
46: Spindle housing 48: Spindle 50: Cutting blade (first cutting blade, second cutting blade)

Claims (2)

A method for processing a workpiece used in grinding, from a back surface side, a disk-shaped workpiece having, on a front surface side, a device region in which a device is provided in each of a plurality of regions partitioned by a planned division line, and a peripheral surplus region surrounding the device region, the method comprising the steps of:
a first holding step of holding the back surface side of the workpiece by a first chuck table;
a first cutting step in which a rotating first cutting blade is caused to cut into an annular region including an outer peripheral edge of the workpiece held by the first chuck table from the surface side of the workpiece to a depth exceeding a depth corresponding to a finished thickness of the workpiece, while rotating the first chuck table, thereby removing a portion of the surface side of the annular region to form a remaining annular remaining portion;
a second holding step of holding the front surface side of the workpiece by a second chuck table;
a second cutting step of removing the remaining portion by rotating the second chuck table while cutting a rotated second cutting blade into the workpiece held by the second chuck table from the back surface side of the workpiece to a position radially inward of the inner edge of the remaining portion of the workpiece and to a depth at which the remaining portion is removed;
a grinding step of grinding the workpiece from the back side to the finished thickness by rotating the second chuck table while contacting the workpiece held by the second chuck table with a grinding stone attached to a grinding wheel rotated about a rotation axis intersecting the rotation axis of the second cutting blade from the back side of the workpiece. The method for processing a workpiece according to claim 1, wherein the workpiece is ground from the back side in the grinding step while the residual portion is removed in the second cutting step.

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