Processing method of workpiece

Abstract

A method for processing a workpiece is provided that can prevent chipping of the workpiece and peeling of a film formed on the surface of the workpiece, and can also reduce the frequency of dressing steps for a cutting blade. [Solution] The method for processing a workpiece according to this embodiment includes a cutting step and a thinning step. The cutting step includes a first cutting step in which the workpiece is cut to a first height position, and a second cutting step in which the workpiece is cut to a second height position. In a plane parallel to a first surface of the workpiece, an angle formed by a first line connecting a center line of the workpiece and the center of a first side surface of the cutting edge portion and the center line of the cutting edge portion is set to a first angle in the first cutting step, and set to a second angle in the second cutting step, the first angle and the second angle being set to be greater than 0 degrees and different from each other.

Description

[Technical Field]

[0001] The present invention relates to a method for processing a workpiece. [Background technology]

[0002] In the manufacture of semiconductor devices such as integrated circuits (ICs), plate-shaped wafers made of semiconductors such as silicon are used as workpieces, and these workpieces are subjected to various processes. Generally, in order to increase the mechanical strength of the workpieces, the corners of the peripheral edges of the workpieces are removed to form rounded chamfered portions (also called beveled portions). Therefore, when the backside of the workpiece is ground to reduce the thickness of the workpiece to, for example, half or less of its thickness before grinding, a sharp edge, known as a knife edge (also called a sharp edge), is formed on the peripheral edges.

[0003] If a knife edge is formed on the peripheral edge of a workpiece, the knife edge may be damaged during transportation of the workpiece after grinding, which may cause cracks or chipping on the peripheral edge. To prevent this, a processing method called edge trimming is performed on the workpiece before grinding, in which a cutting device is used to remove the chamfer on the surface side of the workpiece (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-173961 Summary of the Invention [Problem to be solved by the invention]

[0005] When performing edge trimming, a cutting device equipped with a cutting unit and a chuck table is used. The cutting unit has a spindle and an annular cutting blade attached to the tip of the spindle. The cutting blade has an annular cutting edge portion. The cutting edge portion has an annular first side surface, an annular second side surface opposite the first side surface, and a third side surface between the first side surface and the second side surface. The cutting blade is attached to the spindle so as to be rotatable around the centerline of the cutting edge portion, which passes through the center of the first side surface and the center of the second side surface. The chuck table has an upper surface that serves as a holding surface for holding a workpiece, and can rotate around a rotation center that passes through the center of the holding surface.

[0006] Typically, the edge trimming procedure begins by first suction-holding the workpiece on the chuck table. At this time, the workpiece is suction-held on the chuck table so that the rotation center of the chuck table and the radial center of the workpiece are approximately aligned. Then, the spindle of the cutting unit is rotated, starting the rotation of the cutting blade around the centerline of the cutting edge.

[0007] Then, with the cutting blade and the chuck table positioned so that the first side of the cutting edge portion of the cutting blade is positioned closer to the workpiece than the second side, and the extension of the center line of the cutting edge portion is perpendicular to the extension of the rotation center of the chuck table, the cutting blade is caused to cut into the peripheral portion of the surface of the workpiece.

[0008] After the cutting blade cuts into the peripheral edge of the surface of the workpiece, the chuck table is slowly rotated while the spatial position of the cutting blade, which is rotating at high speed, is kept substantially fixed. Therefore, during cutting, the workpiece comes into contact with not only the third side surface of the cutting edge portion but also the first side surface.

[0009] In this way, when the first side of the cutting edge portion comes into contact with the workpiece, chipping is likely to occur around the periphery of the workpiece surface after cutting. Furthermore, if a thin film such as an oxide film is formed on the surface of the workpiece, the film is likely to peel off from the workpiece at the location where the first side contacts. Furthermore, because the first side of the cutting edge portion wears out, a dressing process to shape the cutting edge portion of the cutting blade must be performed frequently.

[0010] In view of the above circumstances, the present invention provides a method for processing a workpiece that reduces the occurrence of chipping of the workpiece and peeling of a film formed on the surface of the workpiece, and also reduces the frequency of the dressing process for the cutting blade. [Means for solving the problem]

[0011] According to one aspect of the present invention, there is provided a method for processing a workpiece, in which a peripheral portion of a plate-shaped workpiece having a first surface and a second surface opposite to the first surface, with the workpiece center line being a straight line passing through the center of the first surface and the center of the second surface, is cut with a cutting blade having a cutting edge portion having an annular first side surface and an annular second side surface opposite to the first side surface, and the cutting edge portion center line being a straight line passing through the center of the first side surface and the center of the second side surface, the method comprising: moving the workpiece and the cutting blade relatively to one another, and positioning the cutting blade so that the center of the first side surface of the cutting edge portion is located closer to the workpiece center line than the center of the second side surface of the cutting edge portion; rotating the cutting edge portion around the cutting edge portion center line and rotating the workpiece around the workpiece center line, while causing the cutting edge portion of the cutting blade to cut into the workpiece to a first height position located a first distance away from the second surface of the workpiece; a first cutting step of cutting the peripheral edge of the workpiece from the second surface side; and after the first cutting step, the cutting blade is rotated around a center line of the cutting blade and the workpiece is rotated around a center line of the workpiece, while the cutting blade is caused to cut into the workpiece from the first surface side to a second height position that is located a second distance from the second surface on the first surface side and is located closer to the second surface than the first height position. and a second cutting step of further cutting the first surface of the workpiece, wherein an angle formed by a first line connecting a center line of the workpiece and the center of the first side surface of the cutting edge portion and the center line of the cutting edge portion in a plane parallel to the first surface of the workpiece is set to a first angle in the first cutting step and to a second angle in the second cutting step, the first angle and the second angle being greater than 0 degrees and different from each other.

[0012] Preferably, the first angle is greater than the second angle.

[0013] Preferably, the second angle is greater than the first angle.

[0014] Preferably, in the first cutting step, a first cutting blade having a first cutting edge portion is used as the cutting blade having the cutting edge portion, and in the second cutting step, a second cutting blade having a second cutting edge portion is used as the cutting blade having the cutting edge portion, the first cutting edge portion and the second cutting edge portion each containing abrasive grains and a bonding material, and the average grain size of the abrasive grains contained in the second cutting edge portion is smaller than the average grain size of the abrasive grains contained in the first cutting edge portion.

[0015] Preferably, the workpiece has a first substrate having the first surface of the workpiece and a second substrate having the second surface of the workpiece, and the first substrate and the second substrate are stacked so that a third surface of the first substrate opposite the first surface faces a fourth surface of the second substrate opposite the second surface.

[0016] Preferably, the method includes, after the second cutting step, a thinning step of thinning the workpiece by processing the second surface side of the workpiece.

[0017] Preferably, the method includes, after the second cutting step, a thinning step of thinning the workpiece by processing the second surface side of the workpiece. [Effects of the Invention]

[0018] In a method for processing a workpiece according to one aspect of the present invention, a first angle in a first cutting step and a second angle in a second cutting step are set to be greater than 0 degrees. Furthermore, the first angle and the second angle are set to be different angles. In the second cutting step, the cutting edge of the cutting blade is caused to cut into the workpiece up to a second height position that is closer to the second surface than the first height position, thereby cutting the peripheral edge of the workpiece. This reduces the area where the first side of the cutting edge comes into contact with the workpiece 11.

[0019] Therefore, it is possible to reduce the occurrence of chipping at the peripheral edge of the workpiece, reduce peeling of the film formed on the surface of the workpiece, and reduce the frequency of the dressing process for the cutting blade. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1(A) is a perspective view of a workpiece, and FIG. 1(B) is a cross-sectional view taken along line AA of FIG. 1(A). [Figure 2] FIG. 2 is a flow chart showing the flow of each step of the method for processing a workpiece according to this embodiment. [Figure 3] FIG. 3 is a perspective view of the cutting device. [Figure 4] FIG. 4 is a top view of the workpiece and the cutting unit during the first cutting step. [Figure 5] Figure 5(A) is a top view of the workpiece and cutting unit when the first cutting process is being performed, Figure 5(B) is a partial side cross-sectional view of Figure 5(A) viewed from the A1 direction, and Figure 5(C) is a side view of Figure 5(A) viewed from the A2 direction. [Figure 6] Figure 6(A) is a top view of the workpiece and cutting unit when the second cutting process is being performed, Figure 6(B) is a partial side cross-sectional view of Figure 6(A) viewed from the A1 direction, and Figure 6(C) is a side view of Figure 6(A) viewed from the A2 direction. [Figure 7] 10 is a graph showing a cutting volume of a workpiece cut in a cutting step according to the workpiece processing method of the present embodiment. [Figure 8] 10 is a graph showing a cutting volume of a workpiece cut in a cutting step according to a comparative example of a workpiece processing method. [Figure 9] FIG. 9(A) is a perspective view of the workpiece, grinding unit, and chuck table during the thinning process, and FIG. 9(B) is a partially cross-sectional side view of the workpiece, grinding unit, and chuck table during the thinning process. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. First, a workpiece to which a workpiece processing method according to this embodiment is applied will be described. Fig. 1(A) is a perspective view of a workpiece 11, and Fig. 1(B) is a cross-sectional view taken along line AA in Fig. 1(A).

[0022] 1(A) and 1(B), the workpiece 11 is made of a semiconductor material such as silicon and is configured as a disk-shaped plate having a circular first surface (first face) 11a and a circular second surface (second face) 11b opposite to the first surface 11a. However, the material and shape of the workpiece 11 are not limited to these.

[0023] A notch 11c is formed in a portion of the peripheral edge (outer periphery) of the workpiece 11 to indicate the crystal orientation of the workpiece 11. Note that an orientation flat may be formed in the workpiece 11 instead of the notch 11c. Furthermore, the workpiece 11 does not necessarily have to have the notch 11c or the orientation flat formed therein.

[0024] As shown in Fig. 1(A), planned dividing lines 13 are set in a grid pattern on the first surface 11a. The first surface 11a is divided into a plurality of regions by the planned dividing lines 13. A device 15 such as an IC (Integrated Circuit) is formed in each of the plurality of regions. However, the planned dividing lines 13 do not have to be set on the workpiece 11. Furthermore, the device 15 does not have to be formed on the workpiece 11.

[0025] 1(B), the peripheral edge of the first surface 11a of the workpiece 11 is formed with a rounded chamfered portion 11d by removing the corners of the peripheral edge in order to increase the mechanical strength of the workpiece 11. Similarly, the peripheral edge of the second surface 11b of the workpiece 11 is formed with a rounded chamfered portion 11e by removing the corners of the peripheral edge. The diameter of the workpiece 11 is determined by an outer peripheral edge portion 11f located between the chamfered portion 11d and the chamfered portion 11e in the thickness direction of the workpiece 11.

[0026] The diameter (width) of the workpiece 11 is, for example, 299.8 mm or more and 300.2 mm or less, more specifically, 300 mm. The thickness of the workpiece 11 is 755 μm or more and 795 μm or less, typically 775 μm. However, the diameter and thickness of the workpiece 11 are not limited to these.

[0027] In this embodiment, the width of the chamfer is defined as the length a in the radial direction of the workpiece 11 between the end of the chamfered portion 11d opposite the end connected to the outer peripheral end 11f and the outer peripheral end 11f. The width of the chamfer is also defined as the length a between the end of the chamfered portion 11e opposite the end connected to the outer peripheral end 11f and the outer peripheral end 11f. The length (width of the chamfer) a is, for example, 508 μm or less, and typically 500 μm.

[0028] In this embodiment, a straight line passing through the center 11g of the first surface 11a of the workpiece 11 and the center 11h of the second surface 11b is defined as a center line 17 of the workpiece.

[0029] In the above description, the workpiece 11 is composed of a single plate-like object, but the workpiece 11 may also be a laminate (laminated wafer, bonded wafer) in which two plate-like objects (first substrate and second substrate) 11 are bonded together. For example, the first substrate has a first surface and a third surface opposite the first surface. The second substrate has a second surface and a fourth surface opposite the second surface. The first substrate and the second substrate are laminated such that the third surface of the first substrate and the fourth surface of the second substrate face each other, and the first surface of the first substrate and the second surface of the second substrate are exposed.

[0030] Such a laminate is formed, for example, by bonding the third surface of the first substrate and the fourth surface of the second substrate with an organic adhesive, or by bonding oxide films provided on the third surface of the first substrate and the fourth surface of the second substrate and activated by plasma treatment or the like.

[0031] Next, the method for processing the workpiece 11 according to the present embodiment will be described. Fig. 2 is a flow chart showing the flow of each step of the method for processing the workpiece 11 according to the present embodiment. As shown in Fig. 2, the method for processing the workpiece 11 according to the present embodiment includes a first cutting step S11, a second cutting step S12, and a thinning step S20.

[0032] In the cutting step (first cutting step S11, second cutting step S12) S10, the chamfered portions 11d and 11e are cut by a cutting device. Fig. 3 is a perspective view of the cutting device 2. Note that the X1 axis, Y1 axis, and Z1 axis shown in Fig. 3 are perpendicular to one another.

[0033] The cutting device 2 has a base 4 that supports or houses each of the components. A plurality of exterior panels 6 that cover the base 4 are provided above the base 4. A predetermined space is formed inside the box defined by the plurality of exterior panels 6.

[0034] In this predetermined space, for example, a cutting unit 8 is disposed for cutting (i.e., processing) the workpiece 11. The cutting device 2 of this embodiment has one cutting unit 8. However, the cutting device 2 may have a parallel dual structure including two cutting units 8 arranged in mirror symmetry with respect to the X1Z1 plane, like left and right hands.

[0035] The cutting unit 8 has a rectangular columnar spindle housing 10 whose longitudinal direction is arranged substantially parallel to the Y1 axis. A cylindrical spindle 12 is rotatably housed in the spindle housing 10 (see FIG. 4).

[0036] The longitudinal direction of the spindle 12 is arranged along the Y1 axis. That is, the spindle 12 is arranged along the X1Y1 plane. A rotation drive source such as a motor (not shown) is connected to the base end of the spindle 12.

[0037] A cutting blade 14 (see FIG. 4) having an annular cutting edge portion 16 is attached to the tip of the spindle 12. The cutting edge portion 16 has an annular first side surface 16a, an annular second side surface 16b opposite the first side surface 16a, and a third side surface 16c between the first side surface 16a and the second side surface 16b. The cutting edge portion 16 is a member in which abrasive grains made of, for example, diamond or the like are dispersed and fixed by a binder such as metal, resin, or ceramic.

[0038] In this embodiment, a straight line passing through the center 18a of the first side surface 16a (see FIG. 4) and the center 18b of the second side surface 16b (see FIG. 4) is defined as a cutting edge center line .

[0039] The spindle 12 rotates around a rotation axis (not shown) that passes through the center of the spindle and is parallel to the Y1 axis direction due to the rotational drive force applied from the rotational drive source. When the spindle 12 is rotated, the cutting blade 14 also rotates integrally. The center line 28 of the cutting edge portion and the rotation axis of the spindle are substantially aligned.

[0040] 3, a microscope camera unit 34 is fixed to one side of the spindle housing 10. The microscope camera unit 34 has a light source (not shown) such as an LED (Light Emitting Diode), an optical system (not shown) including a condenser lens, and a solid-state image sensor (not shown). The image obtained by the microscope camera unit 34 capturing an image of the workpiece 11 is used for alignment, kerf checking, etc.

[0041] The spindle housing 10 and the microscope camera unit 34 are fixed to the lower end of a Z1-axis moving plate 36. The Z1-axis moving plate 36 can be moved in a direction parallel to the Z1 axis by a Z1-axis moving mechanism (not shown) having a ball screw. The Z1-axis moving mechanism is fixed to a Y1-axis moving plate (not shown).

[0042] The Y1-axis moving plate can be moved in a direction parallel to the Y1-axis by a Y1-axis moving mechanism (not shown) having a ball screw. The positions of the cutting blade 14 and the microscope camera unit 34 along the Y1-axis and the Z1-axis are adjusted by the Y1-axis moving mechanism and the Z1-axis moving mechanism.

[0043] That is, the position of the lower end of the cutting edge portion 16 of the cutting blade 14, which rotates at high speed around the spindle 12, in the Z1-axis direction is adjusted by the Z1-axis movement mechanism. Also, the position of the lower end of the cutting edge portion 16 in the Y1-axis direction is adjusted by the Y1-axis movement mechanism.

[0044] The cutting unit 8 has a pair of cooler nozzles (not shown), a shower nozzle (not shown), and a spray nozzle (not shown) that supply a machining fluid (cutting fluid). The machining fluid is, for example, pure water.

[0045] The pair of cooler nozzles are arranged to sandwich the cutting edge portion 16 in the thickness direction of the cutting edge portion 16 (i.e., the direction along the cutting edge portion center line 28 (see FIG. 4)). The pair of cooler nozzles supply machining fluid to the lower end of the cutting edge portion 16.

[0046] The shower nozzle is disposed between the pair of cooler nozzles in the direction along the Y1 axis. The shower nozzle supplies machining fluid to the outer periphery of the cutting edge portion 16.

[0047] The spray nozzle is disposed near the shower nozzle and supplies the machining fluid to the first surface 11a of the workpiece 11.

[0048] A disk-shaped chuck table (holding table) 20 is provided below the spindle housing 10 to suction-hold the workpiece 11. The chuck table 20 has a disk-shaped frame body 22 (see FIG. 5(B)) made of metal.

[0049] A disk-shaped recess 22b (see FIG. 5(B)) having a diameter smaller than the outer diameter of the outer periphery of the frame 22 is formed on the upper surface of the frame 22. A disk-shaped porous plate 24 (see FIG. 5(B)) having approximately the same diameter as the recess 22b is fixed to this recess 22b. The porous plate 24 is made of, for example, porous ceramics having a large number of pores.

[0050] A suction path 22c is provided inside the frame 22, one end of which is connected to the recess 22b and the other end of which is connected to the outside of the frame 22. A suction source (not shown) such as a vacuum pump is connected to the other end via piping and a valve.

[0051] The negative pressure generated by the suction source can be transmitted to the upper surface 24a of the porous plate 24 via the suction path 22c and the holes in the porous plate 24. The upper surface 22a of the frame 22 and the upper surface 24a of the porous plate 24 are substantially flush with each other, and form a substantially flat holding surface (upper surface) 20a along the X1Y1 plane.

[0052] A rotation drive mechanism (not shown), such as a motor, is provided at the bottom of the chuck table 20. By operating this rotation drive mechanism, the chuck table 20 rotates around a rotation axis 24c (see FIG. 5(B)) that passes through the center of the holding surface 20a of the chuck table 20. The rotation axis 24c is disposed approximately parallel to the Z1 axis. In other words, the rotation axis 24c is disposed so as to be perpendicular to the holding surface 20a.

[0053] The rotary drive mechanism and the chuck table 20 are supported by an X1-axis moving plate (not shown). The X1-axis moving plate is configured to be movable along the X-axis 1 by an X1-axis moving mechanism (not shown) having a ball screw. The relative positions of the lower end of the cutting edge portion 16 and the workpiece 11 in the X1-axis direction are adjusted by the X1-axis moving mechanism.

[0054] 3, a touch panel 32 is provided on the front surface 6a of the exterior panel 6 of the cutting device 2. The touch panel 32 serves as both an input device for an operator to input instructions to a controller (described later) and a display device for displaying images acquired by the microscope camera unit 34, a display window displaying processing conditions, a GUI (Graphical User Interface), etc.

[0055] A cassette mounting table 6b is provided near the front surface 6a. A cassette (not shown) containing one or more workpieces 11 is mounted on the cassette mounting table 6b. The cassette mounting table 6b can be moved along the Z1 axis by an elevator (not shown). The elevator adjusts the height of the cassette mounting table 6b, thereby adjusting the height of the workpieces 11 being carried in and out of the cutting device 2 by the transport mechanism.

[0056] The cutting device 2 also has one or more transport mechanisms (not shown) that can transport the workpiece 11 to the chuck table 20, etc. The workpiece 11 may be transported to the chuck table 20 manually by an operator. In this case, the transport mechanism that transports the workpiece 11 can be omitted.

[0057] The cutting step S10 according to this embodiment is performed using the above-described cutting device 2. The cutting steps (first cutting step S11 and second cutting step S12) S10 will be described below. Fig. 4 is a top view of the workpiece 11 and cutting unit 8 during the first cutting step S11. Note that the cutting edge portion 16 is hatched to make the drawing easier to see.

[0058] In the first cutting step S11, first, the workpiece 11 is held by the chuck table 20 (see FIG. 5(B)). Specifically, the workpiece 11 is placed on the chuck table 20 by a transfer mechanism (not shown) so that the first surface 11a of the workpiece 11 is exposed upward and the second surface 11b faces the holding surface 20a.

[0059] Thereafter, the suction source is activated to apply negative pressure from the suction source to the holding surface 20a of the chuck table 20 through the suction path 22c, etc., thereby sucking and holding the workpiece 11 by the chuck table 20. The position of the workpiece 11 is adjusted so that the rotation axis 24c of the chuck table 20 and the workpiece center line 17 of the workpiece 11 held on the chuck table 20 approximately coincide with each other.

[0060] Next, in order to cut the peripheral portion of the workpiece 11, the relative positional relationship between the cutting edge portion 16 of the cutting blade 14 constituting the cutting unit 8 and the workpiece 11 is adjusted. Specifically, the relative positions of the chuck table 20 and the cutting unit 8 are adjusted so that the extension line of the cutting edge portion center line 28 does not intersect with the workpiece center line 17 in a plane parallel to the first surface 11a of the workpiece 11.

[0061] More specifically, in a plane parallel to the first surface 11a of the workpiece 11, the position of the workpiece 11 in the direction along the X1 axis is adjusted by the X1-axis moving mechanism, and the position of the cutting unit 8 in the direction along the Y1 axis is adjusted by the Y1-axis moving mechanism so that the angle formed by the first straight line 30 connecting the workpiece center line 17 and the center 18a of the first side surface 16a of the cutting edge portion 16 and the cutting edge portion center line 28 is α.

[0062] α is set, for example, between 3° and 10°. If α is greater than 10°, the deviation in the trim width in the first cutting step S11 becomes too large, making it impossible to properly remove the chamfered portion in the second cutting step S12, which will be described later. If α is less than 3°, the trim width in the first cutting step S11 becomes too large, making it impossible to properly remove the chamfered portion in the second cutting step S12, which will be described later. In this embodiment, α is set to 6°. By setting α greater than 0°, the contact area between the first side surface 16a of the cutting edge portion 16 and the workpiece 11 when the cutting edge portion 16 cuts into the workpiece 11 can be made smaller than when α is set to 0°.

[0063] The position of the cutting blade 14 is adjusted by the Y1-axis movement mechanism so that, when viewed from above, the first side surface 16a of the cutting blade 14 overlaps a predetermined length (trim width) from the outer peripheral edge 11f of the workpiece 11 at a position close to the center line 17 of the workpiece. The trim width is set to be slightly larger than the width a of the chamfered portion (see FIG. 1(B)). In this embodiment, the trim width is set to 3 mm.

[0064] Figure 5(A) is a top view of the workpiece and cutting unit when the first cutting process is being performed, Figure 5(B) is a partial cross-sectional side view of Figure 5(A) viewed from the A1 direction, and Figure 5(C) is a partial cross-sectional side view of Figure 5(A) viewed from the A2 direction.

[0065] After the positional relationship between the cutting edge portion 16 and the workpiece 11 has been adjusted as described above, the motor, which is a rotation drive source, rotates the spindle 12, as shown in Figures 5(A) to 5(C). This causes the cutting edge portion 16 of the cutting blade 14 to rotate around the cutting edge portion center line 28. In addition, a machining fluid (cutting fluid) is supplied from a nozzle toward the cutting blade 14.

[0066] Then, the Z1-axis movement mechanism lowers the cutting blade 14. Also, a motor, which is a rotation drive source connected to the chuck table 20, rotates the chuck table 20 around the rotation axis in accordance with the lowering of the cutting blade 14.

[0067] 5(B), the cutting blade 14 cuts into the first surface 11a of the workpiece 11. Then, the amount of descent of the cutting blade 14 by the Z1-axis movement mechanism is adjusted so that the cutting blade 14 cuts into the first surface 11a from the second surface 11b to a first height position 19 located a first distance b toward the first surface 11a.

[0068] In this way, by lowering the rotating cutting blade 14 and causing it to cut into the workpiece 11 while rotating the chuck table 20 about the rotation axis, the cutting blade 14 can be caused to cut along the peripheral edge of the workpiece 11. In other words, the peripheral edge of the workpiece 11 is cut and removed from the first surface 11a to the first height position 19. After cutting of the peripheral edge of the workpiece 11 is completed, the Z1-axis direction movement mechanism raises the cutting unit 8 along the Z1 axis so that the cutting edge portion 16 moves away from the workpiece 11.

[0069] As cutting conditions, for example, the rotation speed of the spindle 12 is set to 30,000 rpm, the flow rate of the machining fluid is set to 4.5 L / min, and the rotation speed of the chuck table 20 is set to 3° / s or more and 5° / s or less. When the thickness of the workpiece 11 is 775 μm, b is, for example, 500 μm or more and 700 μm or less, and is typically 600 μm.

[0070] If the workpiece 11 is a laminate of a first substrate and a second substrate, the thickness of the first substrate is 775 μm, and the thickness of the second substrate is 775 μm, then b is, for example, 765 μm to 785 μm, and is typically 775 μm. That is, in this case, if the workpiece 11 is a laminate of the first substrate and the second substrate, and the cutting blade 14 is caused to cut into the first substrate from the first surface side, the amount by which the cutting blade 14 cuts in is approximately equal to the thickness of the first substrate.

[0071] The flow rate of the machining fluid mentioned above is the total flow rate of the machining fluid supplied from the pair of cooler nozzles, the shower nozzle, and the spray nozzle. The flow rate of the cutting water supplied from the pair of cooler nozzles is, for example, 1.5 L / min. The flow rate of the cutting water supplied from the shower nozzle is, for example, 2.0 L / min. The flow rate of the cutting water supplied from the spray nozzle is, for example, 1.0 L / min.

[0072] After the first cutting step S11 is completed, the second cutting step S12 is performed (see FIG. 2). Fig. 6(A) is a top view of the workpiece 11 and the cutting unit 8 during the second cutting step S12, Fig. 6(B) is a partial side cross-sectional view of Fig. 6(A) viewed from the A1 direction, and Fig. 6(C) is a side view of Fig. 6(A) viewed from the A2 direction.

[0073] In the second cutting step S12, the peripheral edge of the workpiece 11 is further cut. First, the relative positional relationship between the cutting edge portion 16 of the cutting blade 14 constituting the cutting unit 8 and the workpiece 11 is adjusted. Specifically, the relative positions of the chuck table 20 and the cutting unit 8 are adjusted so that an extension line of the cutting edge portion center line 28 does not intersect with the workpiece center line 17 in a plane parallel to the first surface 11a of the workpiece 11.

[0074] More specifically, in a plane parallel to the first surface 11a of the workpiece 11, the position of the workpiece 11 along the X1 axis is adjusted by the X1-axis moving mechanism, and the position of the cutting unit 8 along the Y1 axis is adjusted by the Y1-axis moving mechanism so that the angle formed by the first straight line 30 connecting the workpiece center line 17 and the center 18a of the first side surface 16a of the cutting edge portion 16 and the cutting edge portion center line 28 is β (see Figure 6(A)).

[0075] In this case, β is set to an angle greater than 0° and different from α (see FIG. 5(A)). For example, when α is 3° or greater and 10° or less, β is set to 2° or greater and 9° or less. In this embodiment, β is set to 5°. However, β may be greater or smaller than α. The difference between α and β needs to be 1° or greater. By making β greater than 0°, the contact area between the first side surface 16a of the cutting edge portion 16 and the workpiece 11 when the cutting edge portion 16 cuts into the workpiece 11 can be made smaller than when β is 0°.

[0076] The position of the cutting blade 14 is adjusted by the Y1-axis movement mechanism so that, when viewed from above, the first side surface 16a of the cutting blade 14 overlaps the outer peripheral edge 11f of the workpiece 11 at a position close to the center line 17 of the workpiece by a predetermined length (trim width). The trim width is set to a value equal to or greater than the width a of the chamfered portion (see FIG. 1(B)). For example, the trim width is set to be larger than the trim width in the first cutting step S11 by 20 μm to 50 μm, and is typically set to be larger by 30 μm. In this embodiment, the trim width is set to 3.03 mm, which is 30 μm larger than the trim width (3 mm) in the first cutting step S11.

[0077] After the relationship between the position of the cutting edge portion 16 and the position of the workpiece 11 has been adjusted as described above, the motor, which is the rotation drive source, rotates the cutting blade 14, as shown in Figures 6(A) to 6(C). This causes the cutting edge portion 16 of the cutting blade 14 to rotate around the cutting edge portion center line 28. In addition, machining fluid is supplied from the nozzle toward the cutting blade 14.

[0078] Then, the Z1-axis movement mechanism lowers the cutting blade 14. Also, a motor, which is a rotation drive source connected to the chuck table 20, rotates the chuck table 20 around the rotation axis in accordance with the lowering of the cutting blade 14.

[0079] At this time, as shown in Fig. 6(B), the cutting blade 14 cuts into the workpiece 11 from the first surface 11a side of the workpiece 11. Then, the amount of descent of the cutting blade 14 by the Z-axis direction movement mechanism is adjusted so that the cutting blade 14 cuts from the second surface 11b to a second height position 21 (see Fig. 6(B)) located a second distance c toward the first surface 11a. Note that the second height position 21 is located closer to the second surface 11b than the first height position 19. In other words, the distance c is shorter than the distance b (see Fig. 5(B)).

[0080] In this way, by rotating the chuck table 20 about the rotation axis while lowering the cutting blade 14, the cutting blade 14 can be caused to cut along the peripheral edge of the workpiece 11. In other words, the peripheral edge of the workpiece 11 is cut and removed from the first height position 19 to the second height position 21.

[0081] After the peripheral edge of the workpiece 11 has been cut, the Z1-axis direction movement mechanism raises the cutting unit 8 along the Z1 axis so that the cutting blade portion 16 moves away from the workpiece 11. The cutting conditions (the rotational speed of the spindle 12, the flow rate of the machining fluid, and the rotational speed of the chuck table 20) are the same as those in the first cutting step S11 described above.

[0082] However, the cutting conditions may be set by changing the cutting conditions in the first cutting step S11 so as to reduce damage remaining in the workpiece 11. For example, the rotational speed of the spindle 12 may be set higher and the rotational speed of the chuck table 20 may be set lower than in the first cutting step S11.

[0083] For example, c is set to be smaller than b by 2 μm or more and 10 μm or less. Specifically, when b is 500 μm or more and 700 μm or less, c is, for example, 490 μm or more and 698 μm or less, and is typically 596 μm.

[0084] Here, we will explain the results of calculations of the cross-sectional shapes of the trimmed portions (grooves, steps) formed on the workpiece 11 in each cutting process when α and β are set to different values. Note that we also calculated the cross-sectional shapes of the trimmed portions when α and β are set to the same values, and will explain this as a comparative example.

[0085] Fig. 7 is a graph showing the cutting volume of a workpiece cut in a cutting step according to the workpiece processing method of this embodiment. Fig. 8 is a graph showing the cutting volume of a workpiece cut in a cutting step according to a comparative example of a workpiece processing method. The curves shown in each graph represent the cross-sectional shape of the trim portion (groove, step portion) formed in the workpiece 11 in each cutting step at a position close to the workpiece center line 17. The vertical axis represents height, and the horizontal axis represents the distance from the end of the flat portion of the trim portion close to the workpiece center line 17.

[0086] In the first cutting step S11, α is not 0°, and in the second cutting step S12, β is not 0°. Therefore, the shape of the innermost periphery of the trim portion is not a steep wall surface, but a curved surface. The magnitude of the curvature of this curved surface depends on the magnitudes of α and β. As α and β increase, the curvature of the curved surface (strength of the curve) increases.

[0087] The graph according to this embodiment shown in Figure 7 illustrates a portion of the cutting area of ​​the workpiece 11 when the first cutting step S11 is performed with α set to 6° and the second cutting step S12 is performed with β set to 5°.

[0088] In addition, the graph for the comparative example shown in Figure 8 illustrates a portion of the cutting area of ​​the workpiece 11 when the first cutting step S11 is performed with α set to 6° and the second cutting step S12 is performed with β set to 5°.

[0089] In each graph of Figures 7 and 8, the shape of the trim portion formed on the workpiece 11 in the first cutting step S11 is shown by a solid line, and the shape of the trim portion formed on the workpiece 11 in the second cutting step S12 is shown by a dashed line.

[0090] In this simulation, in the second cutting process S12, the cutting blade 14 cuts into the workpiece 11 to a height position (second height position 21) that is 4 μm lower than the lowest end (first height position 19) of the cutting edge portion 16 of the cutting blade 14 in the first cutting process S11. In other words, the second distance c (see FIG. 6(B)) is 4 μm shorter than the first distance b (see FIG. 5(B)). Furthermore, in the second cutting process S12, the trim width is 30 μm larger than in the first cutting process S11.

[0091] In each figure, the area 23 that is lower than the solid curve and higher than the dashed curve represents the size of the area removed in the second cutting step S12. It can be said that the larger this area is, the larger the cutting volume (volume of the area removed from the workpiece 11) in the second cutting step S12 is.

[0092] In Fig. 7, the solid line and the dashed line intersect. This means that in the second cutting step S12, a portion of the surface of the trim portion formed on the workpiece 11 in the first cutting step S11 is removed, while another portion of the surface of the trim portion is not removed because the cutting blade 14 does not come into contact with this other portion. On the other hand, in Fig. 8, the solid line and the dashed line do not intersect, meaning that the area of ​​the trim portion closer to the workpiece center line 17 is more removed of the workpiece 11.

[0093] 7 and 8, by setting α in the first cutting step S11 and β in the second cutting step S12 at different angles, the cutting volume in the cutting step S10 is reduced compared to when α in the first cutting step S11 and β in the second cutting step S12 are at the same angle. Therefore, by setting α in the first cutting step S11 and β in the second cutting step S12 at different angles, wear on the cutting blade can be reduced compared to when α in the first cutting step S11 and β in the second cutting step S12 are at the same angle, and the frequency of the dressing step can be reduced.

[0094] After the second cutting step S12, a thinning step S20 is performed (see FIG. 2). In the thinning step S20, for example, a grinding wheel having grinding stones arranged in an annular shape is mounted, and a grinding device is used to grind the workpiece 11 with the grinding wheel.

[0095] Fig. 9(A) is a perspective view of the workpiece 11, grinding unit 42, and chuck table 50 during the thinning step S20, and Fig. 9(B) is a partial cross-sectional side view of the workpiece 11, grinding unit 42, and chuck table 50 during the thinning step S20. The X2 axis, Y2 axis, and Z2 axis shown in Fig. 9(A) and Fig. 9(B), respectively, are perpendicular to one another.

[0096] A grinding device 40 for thinning the workpiece 11 will now be described. As shown in Figures 9(A) and 9(B), the grinding device 40 has a grinding unit 42. The grinding unit 42 has a cylindrical spindle 44 that is disposed substantially parallel to the direction along the Z2 axis (vertical direction). A portion of the spindle 44 is rotatably housed in a cylindrical spindle housing (not shown) using an air bearing or the like.

[0097] A rotation drive source such as a motor (not shown) is provided near the upper end of the spindle 44. A Z-axis direction movement mechanism (not shown) having a ball screw is connected to the spindle housing, and the spindle housing can move along the Z2 axis together with the spindle 44.

[0098] The bottom of the spindle 44 protrudes downward below the bottom of the spindle housing, and the center of a disk-shaped wheel mount 46 is fixed to the bottom of the spindle 44. A grinding wheel 48 of approximately the same diameter as the wheel mount 46 is attached to the bottom surface of the wheel mount 46.

[0099] The grinding wheel 48 has an annular wheel base 48a made of a metal material such as an aluminum alloy. A plurality of grinding stones 48b are fixed to the underside of the wheel base 48a. The plurality of grinding stones 48b are arranged at approximately equal intervals around the circumferential direction of the wheel base 48a.

[0100] The grinding wheel 48b is formed by mixing abrasive grains such as diamond or cBN (cubic boron nitride) with a binder (i.e., bond material) such as metal, ceramics, or resin, and then molding and firing the mixture.

[0101] A grinding water supply unit including a nozzle (not shown) for supplying grinding water such as pure water to the grinding region is provided below the grinding unit 42. A disk-shaped chuck table 50 is provided below this nozzle.

[0102] The chuck table 50 is rotatably supported by a disk-shaped table base 56 that includes a bearing. A cylindrical rotation shaft 58 is connected to the bottom of the chuck table 50. In Figures 9(A) and 9(B), the rotation shaft 58 is simplified and shown by a dashed line.

[0103] The rotating shaft 58 is inserted into a through hole (not shown) formed in the table base 56. A driven pulley (not shown) is fixed to the bottom of the rotating shaft 58. In addition, a motor (not shown) and a drive pulley (not shown) fixed to the output shaft of the motor are provided near the rotating shaft 58.

[0104] An endless belt (not shown) is wound around the driven pulley and the drive pulley, and the power of the motor is transmitted to the rotation shaft 58 via the endless belt or the like. The table base 56 is supported by an inclination adjustment mechanism (not shown), and the inclination with respect to the direction along the Z2 axis is adjusted by the inclination adjustment mechanism.

[0105] The chuck table 50 has a configuration similar to that of the chuck table 20 of the cutting device 2 described above. That is, as shown in Fig. 9(B), the chuck table 50 includes a disk-shaped frame body 52 made of a metal such as stainless steel. A recessed portion 52b having a circular opening at the top end is formed on the upper surface side of the frame body 52.

[0106] A disk-shaped holding plate 54 that matches the shape of the recess 52b is fitted into the recess 52b. The holding plate 54 is a plate-shaped porous member made of a material such as ceramics. The holding plate 54 has a substantially flat bottom surface 54b, a cylindrical side surface 54c, and a conical top surface 54a whose central portion protrudes slightly (for example, by a predetermined value of 10 μm to 30 μm) compared to the outer periphery. Note that the shape of the top surface is exaggerated in FIG. 9(B).

[0107] A suction passage 52c is formed inside the frame 52, one end of which is connected to the bottom of the recess 52b of the frame 52. The other end of the suction passage 52c is connected to a suction source (not shown). A valve (not shown) is provided in the suction passage 52c, and when the valve is opened, negative pressure from the suction source acts on the upper surface 54a of the holding plate 54 through the suction passage 52c. As the suction source, for example, a vacuum pump combining an air supply source and an ejector is used. However, a rotary pump or the like may also be used as the suction source.

[0108] The upper surface 54a of the holding plate 54 and the upper surface 52a of the frame 52 are substantially flush with each other, forming a holding surface 50a that holds the workpiece 11. The tilt of the chuck table 50 is adjusted by the tilt adjustment mechanism described above so that a portion of the holding surface 50a becomes substantially parallel to the X2Y2 plane that is perpendicular to the direction along the Z2 axis.

[0109] When negative pressure is transmitted from a suction source (not shown) such as a vacuum pump to the holding plate 54, the workpiece 11 deforms to follow the shape of the holding surface 50a and is held by suction on the holding surface 50a.

[0110] The thinning step S20 is performed using the grinding device 40. In the thinning step S20, first, in order to protect the device 15 provided on the first surface 11a of the workpiece 11, a protective tape (not shown) made of resin and having approximately the same diameter as the first surface 11a is attached to the first surface 11a.

[0111] Then, the workpiece 11 is placed on the holding surface 50a of the chuck table 50 so that the center line 17 of the workpiece substantially coincides with the rotation axis 58 of the chuck table 50. At this time, the second surface 11b of the workpiece 11 is exposed upward, and the first surface 11a faces the holding surface 40a via the protective tape.

[0112] Then, the spindle 44 and the rotating shaft 58 are rotated at a predetermined rotational speed, and the grinding unit 42 is moved downward along the Z2 axis at a predetermined speed (i.e., grinding feed) while supplying nozzle grinding fluid to the contact area between the grinding wheel 48b and the workpiece 11.

[0113] As grinding conditions, for example, the rotation speed of the spindle 44 is set to 3000 rpm, the rotation speed of the chuck table 50 is set to 300 rpm, the grinding feed rate is set to 3.0 μm / s, and the flow rate of the grinding fluid is set to 4.0 L / min. However, the grinding conditions are not limited to these.

[0114] Under the grinding conditions described above, the second surface 11b of the workpiece 11 is uniformly ground with the grinding wheel 48. By setting the removal amount (grinding feed rate) by the grinding wheel to be equal to or greater than the second distance c left in the second cutting step S12, the chamfered portions 11d and 11e remaining on the periphery of the workpiece 11 are completely removed, and the workpiece 11 is formed to a predetermined thickness. In other words, after the thinning step S20 is performed, no sharp edges remain on the periphery of the workpiece 11. Note that the thinning step S20 may be performed by wet etching or dry etching instead of grinding. This completes the flow of the workpiece processing method according to this embodiment.

[0115] As described above, the workpiece 11 may be a laminate formed by bonding two wafers together. In this case, the peripheral portion of one of the substrates may be fully cut in the cutting process (either or both of the first cutting process S11 and the second cutting process S12). For example, if the workpiece 11 is a laminate formed by bonding a first substrate and a second substrate together, the total thickness of the workpiece 11 cut in the first cutting process S11 and the second cutting process S12 of the cutting process S10 may be set to be equal to or greater than the thickness of the first substrate. In this case, the cutting blade 14 may cut into the second substrate, or may cut into the adhesive layer between the first and second substrates without cutting into the second substrate.

[0116] Furthermore, although the same cutting unit 8 is used in the first cutting step S11 and the second cutting step S12 in the above description, different cutting units may be used in the first cutting step S11 and the second cutting step S12. For example, in the cutting device having the above-mentioned parallel dual structure, the first cutting step S11 may be performed by one of the two cutting units, and the second cutting step S12 may be performed by the other cutting unit.

[0117] In such a case, the average particle size of the abrasive grains contained in the cutting edge portion 16 of the cutting unit 8 used in the second cutting step S12 may be smaller than the average particle size of the abrasive grains contained in the cutting edge portion 16 of the cutting unit 8 used in the first cutting step S11. By doing so, it is possible to reduce the surface roughness of the cut surface (bottom and side surfaces of the trimmed portion) of the workpiece 11 after the second cutting step S12.

[0118] Furthermore, generally, cutting edge portions 16 with abrasive grains having a relatively small average grain size are subject to greater wear than cutting edge portions 16 with abrasive grains having a relatively large average grain size. Therefore, by using cutting edge portions 16 with a relatively large average grain size in the first cutting step S11, wear of the cutting edge portions 16 in the first cutting step S11 can be reduced more than when using cutting blades 14 with abrasive grains having a relatively small average grain size in the first cutting step S11 as in the second cutting step S12. As a result, the frequency of dressing the cutting blades 14 can be reduced.

[0119] For example, the grain size of the abrasive grains contained in the cutting edge portion 16 of the cutting unit 8 used in the first cutting step S11 can be #400, and the grain size of the abrasive grains contained in the cutting edge portion 16 of the cutting unit 8 used in the second cutting step S12 can be #2000. The above grain sizes are based on JIS R 6001-2:2017 (Grain size of abrasives for grinding wheels - Part 2: Fine powder) specified in the Japanese Industrial Standards (JIS).

[0120] For example, when forming a film on the workpiece 11 after the cutting process, by making the surface roughness of the surface of the workpiece 11 on which the film is to be formed sufficiently small compared to the thickness of the film to be formed, it is possible to form a uniform film on the workpiece 11. Furthermore, when the surface roughness is sufficiently small compared to the thickness of the film, the film adheres to the surface of the trim part of the workpiece 11 with sufficient adhesion force, thereby suppressing peeling of the film in the trim part.

[0121] As described above, in this embodiment, in the cutting steps (first cutting step S11, second cutting step S12), α and β are set to be greater than 0° and to be different angles. This reduces the contact area between the workpiece 11 and the first side surface 16a of the cutting edge portion 16 in the second cutting step S12, thereby reducing the occurrence of chipping of the workpiece 11 and the peeling of the film formed on the surface of the workpiece 11. Furthermore, wear of the first side surface 16a of the cutting edge portion 16 can be reduced. This reduces the frequency of the dressing step for the cutting blade 14.

[0122] The structures, methods, and the like according to the above-described embodiments and modifications may be modified and implemented without departing from the scope of the present invention. [Explanation of symbols]

[0123] 11: Workpiece 11a: 1st surface (1st surface) 11b: Second surface (second surface) 11c: Notch 11d: Chamfered part 11e: Chamfered part 11f: Outer edge 11g: Center 11h: Center 13: Planned division line 15: Device 17: Workpiece center line 19: First height position 21: Second height position 23: Processing area 2:Cutting device 4: Base 6: Exterior panel 6a:Front 6b: Cassette stand 8: Cutting unit 10: Spindle housing 12: Spindle 14: Cutting blade 16: Cutting edge 16a: 1st side 16b: 2nd side 16c: 3rd side 18a: Center 18b: Center 20: Chuck table 20a: Holding surface 22:Frame body 22a:Top surface 22b: recess 22c: Suction path 24: Porous board 24a:Top surface 26: Center of rotation 28: Cutting edge center line 30: 1st straight line 32: Touch panel 34: Microscope camera unit 36:Z1 axis moving plate 40: Grinding equipment 42: Grinding unit 44: Spindle 46: Wheel mount 48: Grinding wheel 48a: Wheel base 48b: Grinding wheel 50: Chuck table 50a: Holding surface 52: Frame 52a:Top surface 52b: recess 52c: Suction path 54: Holding plate 54a:Top surface 54b: bottom 54c: Side 56: Table base 58: Rotation axis

Claims

1. A method for processing a workpiece, comprising: cutting a peripheral portion of a plate-shaped workpiece having a first surface and a second surface opposite to the first surface, with the workpiece center line being a straight line passing through a center of the first surface and a center of the second surface, with a cutting blade having a cutting edge portion having an annular first side surface and an annular second side surface opposite to the first side surface, with the cutting edge portion center line being a straight line passing through a center of the first side surface and a center of the second side surface, a first cutting step of moving the workpiece and the cutting blade relatively to position the cutting blade so that the center of the first side surface of the cutting edge portion is located closer to the center line of the workpiece than the center of the second side surface of the cutting edge portion, and rotating the cutting edge portion around the center line of the cutting edge portion and rotating the workpiece around the center line of the workpiece, while cutting the cutting edge portion of the cutting blade into the workpiece from the first surface side by a first distance from the second surface to a first height position located on the first surface side; and a second cutting step of, after the first cutting step, rotating the cutting edge portion around a center line of the cutting edge portion and rotating the workpiece around a center line of the workpiece, causing the cutting edge portion of the cutting blade to cut into the workpiece from the first surface side to a second height position that is located a second distance from the second surface toward the first surface and is located closer to the second surface than the first height position, thereby further cutting the peripheral portion of the workpiece, an angle formed by a first straight line connecting a center line of the workpiece and the center of the first side surface of the cutting edge portion, and the center line of the cutting edge portion, in a plane parallel to the first surface of the workpiece is set to a first angle in the first cutting step, and set to a second angle in the second cutting step; The method for machining a workpiece, wherein the first angle and the second angle are greater than 0 degrees and are different angles.

2. The method for machining a workpiece according to claim 1 , wherein the first angle is greater than the second angle.

3. The method for machining a workpiece according to claim 1 , wherein the second angle is greater than the first angle.

4. In the first cutting step, a first cutting blade having a first cutting edge portion is used as the cutting blade having the cutting edge portion, and in the second cutting step, a second cutting blade having a second cutting edge portion is used as the cutting blade having the cutting edge portion, the first cutting edge portion and the second cutting edge portion each include abrasive grains and a bonding material; 4. The method for processing a workpiece according to claim 1, wherein the average particle size of the abrasive grains contained in the second cutting edge portion is smaller than the average particle size of the abrasive grains contained in the first cutting edge portion.

5. the workpiece includes a first substrate having the first surface of the workpiece and a second substrate having the second surface of the workpiece; 4. A method for processing a workpiece according to claim 1, wherein the first substrate and the second substrate are stacked such that a third surface of the first substrate opposite the first surface faces a fourth surface of the second substrate opposite the second surface.

6. 4. The method for processing a workpiece according to claim 1, further comprising, after the second cutting step, a thinning step of processing the second surface side of the workpiece to thin the workpiece.

7. 6. The method for processing a workpiece according to claim 5, further comprising, after the second cutting step, a thinning step of processing the second surface side of the workpiece to thin the workpiece.

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