Cutting method

Abstract

To prevent an end material chip from scattering without forming a non-cutting region, and to singulate a workpiece to a plurality of device chips.SOLUTION: A cutting method for cutting a workpiece having a device region and an outer peripheral region on a front surface side includes: a holding step of holding the workpiece with a holding table via a dicing tape; a first cutting step of removing an end material chip containing region with a predetermined length from an outer peripheral edge in the outer peripheral region by rotating the holding table in a state where, after the holding step, a first cutting blade is cut into the outer peripheral region of the workpiece to a depth where the lower end of the first cutting blade reaches the dicing tape; and a second cutting step of cutting the workpiece along each cutting schedule line in a state where, after the first cutting step, a second cutting blade is cut into the workpiece to the depth where the lower end of the second cutting blade reaches the dicing tape.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a cutting method for cutting, with a cutting blade, a workpiece having a device region in which a plurality of devices are provided and an outer circumferential region surrounding the device region. [Background technology]

[0002] A disk-shaped workpiece such as a semiconductor wafer is known, which has a grid of dividing lines (streets) set on its front surface and has devices formed in each of the areas partitioned by the streets. The front surface of the workpiece has a device area having a plurality of devices and a peripheral area that surrounds the device area and has no devices.

[0003] When cutting a workpiece to separate it into device chips, for example, first, a resin dicing tape is attached to the back side of the workpiece, and the back side is suction-held by the holding surface of the chuck table via the dicing tape. At this time, the front side of the workpiece is exposed upward. Next, the orientation of the chuck table is adjusted so that the street along one direction is approximately parallel to the processing feed direction.

[0004] Then, with the lower end of the rotating cutting blade positioned at a height between the back surface of the workpiece and the holding surface, the chuck table is moved in the processing feed direction to cut from the front surface to the back surface of the workpiece (i.e., a full cut).

[0005] The workpiece is fully cut along each street to divide the device region into a plurality of rectangular device chips, but in the peripheral region, a plurality of scrap chips are formed that are not rectangular but triangular or trapezoidal.

[0006] However, since the peripheral regions of the front and back surfaces are usually formed with chamfered portions, the peripheral regions have low adhesion to the dicing tape (i.e., weak adhesive strength). In particular, triangular scrap chips have a smaller area than rectangular device chips, so they tend to peel off from the dicing tape and fly off during cutting (i.e., chips are prone to flying off).

[0007] When the scattered end chips collide with the cutting blade, the cutting blade may be damaged. In order to prevent such scattering of end chips, a cutting method has been proposed in which the cutting end side of the workpiece is not cut, but an uncut area is formed (see, for example, Patent Document 1).

[0008] However, if uncut areas are formed on all streets that are approximately parallel to one direction, there is a high risk of erroneously picking up scrap chips that include uncut areas in the device chip pick-up process that follows the cutting process. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2014-204015 A Summary of the Invention [Problem to be solved by the invention]

[0010] If an end material chip including an uncut area is mistakenly picked up, there is a concern that the end material chip may fall, causing damage to the device chip or adversely affecting the cutting device or other processing equipment.

[0011] The present invention has been made in consideration of these problems, and aims to suppress the scattering of scrap chips without forming uncut areas, and to singulate the workpiece into multiple device chips. [Means for solving the problem]

[0012] According to one aspect of the present invention, there is provided a cutting method for cutting a workpiece having a device area on the front side, in which a device is provided in each of a plurality of areas partitioned by a plurality of planned cutting lines set in a grid pattern, and a peripheral area surrounding the device area on the front side, the cutting method comprising: an attachment step of attaching a dicing tape to the back side of the workpiece; a holding step of holding the workpiece on a holding table via the dicing tape after the attachment step; a first cutting step of removing a scrap chip-containing area of ​​a predetermined length from the outer edge of the peripheral area by rotating the holding table with the first cutting blade cut into the peripheral area of ​​the workpiece to a depth where the lower end of the first cutting blade reaches the dicing tape after the holding step; and a second cutting step of cutting the workpiece along each planned cutting line with the second cutting blade cut into the workpiece to a depth where the lower end of the second cutting blade reaches the dicing tape after the first cutting step.

[0013] Preferably, in the first cutting step, a first cutting unit having a first spindle and a first cutting blade mounted on the first spindle is used to remove the scrap chip containing area, and in the second cutting step, a second cutting unit having a second spindle and a second cutting blade having a thinner blade thickness than the cutting edge of the first cutting blade is used to cut the workpiece along each of the intended cutting lines. Effect of the Invention

[0014] In a cutting method according to one aspect of the present invention, a first cutting blade is inserted into the outer peripheral region of the workpiece to a depth where the lower end of the first cutting blade reaches the dicing tape, and the holding table is rotated in this state to remove a region of a predetermined width from the outer edge of the outer peripheral region (first cutting step). This removes a region of a predetermined width that has a weak adhesive force to the dicing tape from the workpiece.

[0015] Then, after the first cutting step, the second cutting blade is caused to cut into the workpiece to a depth where the lower end of the second cutting blade reaches the dicing tape, and the workpiece is cut along each of the intended cutting lines (second cutting step).

[0016] In this way, the first cutting step removes a region of a certain width where the adhesive strength with the dicing tape is weak, and the scrap chips that tend to scatter are removed in advance in the second cutting step, so that scattering of the scrap chips can be suppressed without forming an uncut region. [Brief description of the drawings]

[0017] [Figure 1] FIG. [Diagram 2] FIG. [Diagram 3] FIG. [Figure 4] FIG. 2 is an enlarged cross-sectional view of the outer peripheral region of the workpiece. [Diagram 5] FIG. 11 is a diagram showing a step of identifying an end chip containing area. [Figure 6] FIG. 2 is a diagram showing a first cutting step. [Figure 7] FIG. 7(A) is a diagram showing the first half of the second cutting step, and FIG. 7(B) is a diagram showing the second half of the second cutting step. [Figure 8] FIG. 11 is an enlarged cross-sectional view of an outer circumferential region of a workpiece according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Fig. 1 is a perspective view of a cutting device 2 for performing a cutting method according to the first embodiment. The X-axis direction (processing feed direction), the Y-axis direction (indexing feed direction), and the Z-axis direction (height direction, vertical direction) shown in Fig. 1 are mutually orthogonal.

[0019] The cutting device 2 includes a base 4 that supports each of the components. An opening 4a is formed in a front corner (one corner in the Y-axis direction) of the base 4. A cassette support table 8 that is raised and lowered by a lifting mechanism (not shown) is provided within the opening 4a.

[0020] A cassette 10 that accommodates a plurality of workpieces 11 is mounted on the upper surface of the cassette support stage 8. For convenience of explanation, only the outline of the cassette 10 is shown in Fig. 1. The workpieces 11 in this embodiment are disk-shaped semiconductor wafers made of Si (silicon).

[0021] However, the workpiece 11 may be made of a semiconductor material such as SiC (silicon carbide), GaN (gallium nitride), GaAs (gallium arsenide), etc. A plurality of cutting lines (streets) 13 (see FIG. 3) are set in a lattice pattern on the front surface 11a of the workpiece 11.

[0022] As shown in FIG. 3, in each of the rectangular regions partitioned by the plurality of cutting lines 13, a device 15 such as an IC (Integrated Circuit) or an LSI (Large Scale Integration) is formed.

[0023] In this manner, on the front surface 11a side, there is a device region 17a in which a plurality of devices 15 are formed. Also, on the front surface 11a side, there is a peripheral region 17b which does not have any devices 15 and surrounds the device region 17a.

[0024] 4, the workpiece 11 of this embodiment does not have a chamfered portion on the outer periphery of the front surface 11a and the back surface 11b. After the outer periphery of the workpiece 11 on the front surface 11a side is removed by edge trimming, the back surface 11b side is ground to be thinned.

[0025] Furthermore, a passivation film 19 (see FIG. 4) is formed on the front surface 11a side of the workpiece 11. The passivation film 19 is a glass film such as a PSG (Phosphorus Silicon Glass) film or a BPSG (Boro-Phospho Silicate Glass) film.

[0026] The passivation film 19 is formed, for example, by plasma CVD (Chemical Vapor Deposition) in a state where the back surface 11b side is held by an electrostatic chuck (not shown) and the front surface 11a side is exposed. However, as shown in Fig. 4, the passivation film 19 is formed on the side surface 11c of the workpiece 11 and the outer periphery of the back surface 11b in addition to the entire front surface 11a side.

[0027] Therefore, on the back surface 11b, there are an annular covered region 11b1 covered with the passivation film 19 and a substantially circular exposed region 11b2 that is not covered with the passivation film 19. The covered region 11b1 has a length (i.e., width) L1 of 1.5 mm or less from the outer circumferential edge 11d of the back surface 11b toward the center of the back surface 11b.

[0028] The dicing tape 21 (see FIG. 3) has a base layer and an adhesive layer (glue layer) provided on one surface of the base layer. The dicing tape 21 has a diameter larger than that of the workpiece 11. The workpiece 11 is attached to approximately the center of the dicing tape 21.

[0029] However, since the adhesive strength of the dicing tape 21 in the covered area 11b1 is weaker than the adhesive strength of the dicing tape 21 in the exposed area 11b2, scrap chips 15a2 (see Figure 5) are likely to fly off in the covered area 11b1 when cutting the workpiece 11 along the intended cutting line 13.

[0030] 3, one surface of a metal frame 23 is attached to the outer periphery of the dicing tape 21 so as to surround the workpiece 11. To attach the dicing tape 21 to the workpiece 11 and the frame 23, for example, a tape attachment device (not shown) is used.

[0031] The tape application device has a chuck table that suction-holds the front surface 11a side of the workpiece 11. The outer periphery of the chuck table is formed with an annular stepped portion (not shown) that is recessed below the holding surface of the chuck table.

[0032] The depth of the step is set to a predetermined depth. For example, the predetermined depth of the step is set so that when the front surface 11a side is suction-held by the holding surface and the frame 23 is placed on the step, the height of the back surface 11b and the top surface of the frame 23 are approximately the same.

[0033] After an adhesive layer of a rectangular dicing tape 21 having an area larger than the frame 23 is attached to the rear surface 11b and the upper surface of the frame 23, the heights of which are aligned, the dicing tape 21 is cut into a circle with a cutter (not shown). In this manner, a workpiece unit 25 is formed in which the workpiece 11 is supported by the frame 23 via the dicing tape 21.

[0034] Returning to Fig. 1, a rectangular opening 4b whose longitudinal direction is approximately parallel to the X-axis direction is formed behind the opening 4a (the other side in the Y-axis direction). A rectangular table cover 12 is provided inside the opening 4b. Accordion-shaped covers 14 are provided on both sides of the table cover 12 in the X-axis direction.

[0035] A disk-shaped chuck table (holding table) 16 is provided on the table cover 12. The chuck table 16 has a disk-shaped frame body made of metal. A disk-shaped recess is formed in the upper part of the frame body.

[0036] A circular porous plate made of porous ceramics is fixed in the recess. The upper surfaces of the frame and the porous plate form a substantially flush holding surface 16a. When negative pressure is transmitted from a suction source (not shown) such as an ejector to the porous plate through a predetermined flow path formed in the frame, negative pressure is generated on the holding surface 16a.

[0037] Four clamps 16b are provided around the periphery of the frame body to fix the frame 23 from all four sides. In addition, a rotation drive source (not shown) such as a motor is connected to the lower part of the chuck table 16 to rotate the chuck table 16 around a rotation axis approximately parallel to the Z-axis direction.

[0038] The rotary drive source is supported by an X-axis moving plate (not shown). The X-axis moving plate is slidably attached to a pair of X-axis guide rails (not shown) arranged substantially parallel to the X-axis direction. A nut portion (not shown) is provided on the lower surface side of the X-axis moving plate, and a ball screw (not shown) arranged substantially parallel to the X-axis direction is rotatably connected to the nut portion.

[0039] A drive source (not shown) such as a pulse motor is connected to one end of the ball screw. The drive source, ball screw, a pair of X-axis guide rails, X-axis moving plate, etc. constitute an X-axis moving mechanism. The table cover 12, chuck table 16, rotation drive source, etc. move together in the X-axis direction by the X-axis moving mechanism.

[0040] A pair of guide rails 18 are provided above the opening 4b along the Y-axis direction. The workpiece unit 25 in the cassette 10 is pulled out of the cassette 10 onto the pair of guide rails 18 by a first transport unit (not shown), and then transported to the holding surface 16a.

[0041] A gate-shaped support structure 20 is disposed above the opening 4b so as to straddle the opening 4b. A pair of guide rails 22 disposed approximately parallel to the Y-axis direction are fixed to one side surface of the support structure 20 in the X-axis direction.

[0042] Two Y-axis moving plates 24a, 24b are attached to the pair of guide rails 22 in a manner that they can slide independently of each other. A nut portion (not shown) is provided on the back side of each of the Y-axis moving plates 24a, 24.

[0043] A ball screw 26a arranged substantially parallel to the Y-axis direction is rotatably connected to a nut portion of the Y-axis moving plate 24a. A drive source 28a such as a pulse motor is connected to one end of the ball screw 26a.

[0044] When the driving source 28a is operated, the Y-axis moving plate 24a moves along the Y-axis direction. The pair of guide rails 22, the Y-axis moving plate 24a, the ball screw 26a, etc. constitute a first Y-axis moving mechanism.

[0045] Similarly, a ball screw 26b arranged substantially parallel to the Y-axis direction is rotatably connected to a nut portion of the Y-axis moving plate 24b. A drive source (not shown) such as a pulse motor is connected to one end of the ball screw 26b.

[0046] When a drive source (not shown) is operated, the Y-axis moving plate 24b moves along the Y-axis direction. The pair of guide rails 22, the Y-axis moving plate 24b, the ball screw 26b, etc. configure a second Y-axis moving mechanism.

[0047] A pair of guide rails 30a arranged substantially parallel to the Z-axis direction is fixed to the surface of the Y-axis moving plate 24a. A Z-axis moving plate 32a is attached to the pair of guide rails 30a so as to be slidable in the Z-axis direction.

[0048] A nut portion (not shown) is provided on the rear side of the Z-axis moving plate 32a. A ball screw 34a arranged substantially parallel to the Z-axis direction is rotatably connected to the nut portion. A driving source 36a such as a pulse motor is connected to the upper end of the ball screw 34a.

[0049] When the driving source 36a is operated, the Z-axis moving plate 32a moves along the Z-axis direction. The pair of guide rails 30a, the Z-axis moving plate 32a, the ball screw 34a, etc. constitute a first Z-axis moving mechanism.

[0050] Similarly, a pair of guide rails 30b arranged substantially parallel to the Z-axis direction is fixed to the surface of the Y-axis moving plate 24b. A Z-axis moving plate 32b is attached to the pair of guide rails 30b so as to be slidable in the Z-axis direction.

[0051] A nut portion (not shown) is provided on the rear side of the Z-axis moving plate 32b. A ball screw 34b arranged substantially parallel to the Z-axis direction is rotatably connected to the nut portion. A driving source 36b such as a pulse motor is connected to the upper end of the ball screw 34b.

[0052] When the driving source 36b is operated, the Z-axis moving plate 32b moves along the Z-axis direction. The pair of guide rails 30b, the Z-axis moving plate 32b, the ball screw 34b, etc. constitute a second Z-axis moving mechanism.

[0053] A first cutting unit 38a is fixed to the lower end of the Z-axis moving plate 32a. The first cutting unit 38a has a cylindrical spindle housing 40a (see FIG. 6). As shown in FIG. 6, a cylindrical first spindle 42a is rotatably accommodated in the spindle housing 40a.

[0054] A rotary drive source such as a motor is provided on the base end side of the first spindle 42a. A first cutting blade 44a having an annular cutting edge is attached to the tip end of the first spindle 42a.

[0055] The first cutting blade 44a cuts and removes the outer periphery of the workpiece 11 in a first cutting step S40 described later. The cutting edge of the first cutting blade 44a has a relatively large thickness. The cutting edge of the first cutting blade 44a has a thickness of 1 mm or more and 4 mm or less, for example, 2 mm.

[0056] A second cutting unit 38b is fixed to the lower end of the Z-axis moving plate 32b. The second cutting unit 38b has a cylindrical spindle housing 40b (see FIG. 7). As shown in FIG. 7, a cylindrical second spindle 42b is rotatably accommodated in the spindle housing 40b.

[0057] A rotary drive source such as a motor is provided on the base end side of the second spindle 42b. A second cutting blade 44b having an annular cutting edge is attached to the tip end of the second spindle 42b.

[0058] The second cutting blade 44b cuts the workpiece 11 along each of the intended cutting lines 13 in a second cutting step S50 described later. The thickness of the cutting edge of the second cutting blade 44b is thinner than that of the first cutting blade 44a. The thickness of the cutting edge of the second cutting blade 44b is 15 μm or more and 110 μmm or less, for example, 45 μm.

[0059] Returning to Fig. 1, a camera unit 46a is fixed to the spindle housing 40a adjacent to the first cutting unit 38a. Similarly, a camera unit 46b is fixed to the spindle housing 40b adjacent to the second cutting unit 38b.

[0060] Each of the camera units 46a and 46b includes a predetermined optical system such as a condenser lens and an image pickup element. A circular opening 4c is formed behind the opening 4b. A spinner cleaning unit 48 is provided in the opening 4c.

[0061] After cutting, the workpiece 11 is transported by a second transport unit (not shown) from the chuck table 16 to the spinner cleaning unit 48 and cleaned. After cleaning, the workpiece 11 is carried into the cassette 10 via the pair of guide rails 18 by the first transport unit.

[0062] The lifting mechanism, the X-axis moving mechanism, the chuck table 16, the pair of guide rails 18, the first and second Y-axis moving mechanisms, the first and second Z-axis moving mechanisms, the first and second transport units, the spinner cleaning unit 48, etc. are controlled by a control unit (not shown).

[0063] The control unit is configured by a computer including, for example, a processor (processing device) represented by a CPU (Central Processing Unit), a main storage device such as a DRAM (Dynamic Random Access Memory), and an auxiliary storage device such as a flash memory.

[0064] The auxiliary storage device stores software including a predetermined program. The functions of the control unit are realized by operating the processing device and the like in accordance with this software. The auxiliary storage device stores programs and the like for performing image processing on images captured by the camera units 46a and 46b.

[0065] Next, a cutting method using the cutting device 2 will be described with reference to Figures 2 to 7(B) Fig. 2 is a flow diagram of the cutting method according to the first embodiment.

[0066] First, using the above-mentioned tape application device (not shown), a dicing tape 21 is applied to the back surface 11b of the workpiece 11 on which the passivation film 19 (see FIG. 4) is formed, to form a workpiece unit 25 (see FIG. 3) (application step S10).

[0067] Fig. 3 is a perspective view of workpiece unit 25. Fig. 4 is an enlarged cross-sectional view of outer circumferential region 17b of workpiece 11. As described above, the range of rear surface 11b from outer circumferential edge 11d to a predetermined length L1 is a covered region 11b1 covered with passivation film 19.

[0068] After the attachment step S10, the workpiece unit 25 (workpiece 11) is transported to the cutting device 2 while being housed in the cassette 10. Then, the workpiece 11 is carried out to the chuck table 16 by a first transport unit or the like, and the back surface 11b side is suction-held by the holding surface 16a via the dicing tape 21 (holding step S20).

[0069] After the holding step S20, for example, the control unit (not shown) identifies the outer peripheral edge 11d of the workpiece 11 and each of the intended cutting lines 13 by capturing an image of the surface 11a side of the workpiece 11 with the camera unit 46a.

[0070] 5, one rectangular device 15 in device region 17a is surrounded by four cutting lines 13. However, in outer peripheral region 17b, there are a substantially trapezoidal region surrounded by three cutting lines 13 and a triangular region surrounded by two cutting lines 13.

[0071] When the workpiece 11 is cut along each of the lines to cut 13, the trapezoidal regions become scrap chips 15a1, and the triangular regions become scrap chips 15a2. In FIG. 5, the regions that become scrap chips 15a2 are shown circled with dashed lines.

[0072] In particular, the triangular scrap chips 15a2 have a smaller area than the rectangular device 15. In addition, the covering region 11b1 (see FIG. 4) has a lower adhesive strength with the adhesive layer than the exposed region 11b2. Therefore, the triangular scrap chips 15a2 present in the covering region 11b1 are likely to peel off from the dicing tape 21 and scatter during cutting.

[0073] Therefore, in this embodiment, first, the control unit identifies the scrap chip containing region 17c in which the triangular scrap chips 15a2 are formed in the covered region 11b1 (scrap chip containing region identifying step S30). Fig. 5 is a diagram showing the scrap chip containing region identifying step S30.

[0074] Specifically, the control unit determines a circumscribing circle 11e that circumscribes the corner of the triangular scrap chip 15a2 that is closest to the center of the surface 11a by image processing, etc. Then, the control unit identifies a region of a predetermined length from the outer peripheral edge 11d to the circumscribing circle 11e in the outer peripheral region 17b as the scrap chip-containing region 17c.

[0075] In this embodiment, the distance from the outer peripheral edge 11d to the circumscribed circle 11e is equal to or greater than the length L1 of the covered region 11b1, for example, 1.5 mm. If the scrap chip-containing region 17c has already been specified, S30 may be omitted and the operator may input the cutting region into the control unit.

[0076] The scrap chip containing region 17c is cut and removed using a first cutting blade 44a to prevent the scrap chips 15a2 from scattering (first cutting step S40). Figure 6 is a diagram showing the first cutting step S40. Note that the dicing tape 21 and the frame 23 are omitted in Figure 6.

[0077] In the first cutting step S40, the cutting edge of the first cutting blade 44a is caused to cut into the end chip containing region 17c to a depth where the lower end of the first cutting blade 44a reaches the dicing tape 21.

[0078] At this time, the first cutting blade 44a may be lowered and cut into the workpiece 11 by chopper cutting, or the first cutting blade 44a may be moved along the X-axis direction and cut into the workpiece 11.

[0079] In this manner, with the first cutting blade 44a cutting into the workpiece 11, the chuck table 16 is rotated to cut and remove an annular region (e.g., 1.5 mm wide) from the outer circumferential edge 11d to the circumscribed circle 11e. At this time, the position of the first cutting blade 44a in the Y-axis direction may be adjusted while the chuck table 16 is rotating.

[0080] After the first cutting step S40, the workpiece 11 is cut along each of the intended cutting lines 13 using the second cutting blade 44b (second cutting step S50), thereby dividing the workpiece 11 into a plurality of device chips.

[0081] 7A is a diagram showing the first half of the second cutting step S50. In the first half, through alignment, adjustment of the rotation angle of the chuck table 16, etc., a plurality of cutting lines 13 each parallel to one direction are positioned approximately parallel to the X-axis direction.

[0082] Next, outside the chuck table 16, the second cutting blade 44b is placed on an extension of one of the intended cutting lines 13, and the height position of the lower end of the second cutting blade 44b is positioned between the holding surface 16a and the back surface 11b.

[0083] Then, the X-axis movement mechanism moves the chuck table 16 and the second cutting blade 44b relatively in the processing feed direction. As a result, the workpiece 11 is cut with the second cutting blade 44b cutting into the workpiece to a depth where the lower end of the second cutting blade 44b reaches the dicing tape 21.

[0084] After cutting the workpiece 11 along one of the planned cutting lines 13, the second cutting unit 38b is indexed and fed by a predetermined index amount along the Y-axis direction, and then the workpiece 11 is cut along another of the planned cutting lines 13 adjacent to the one of the planned cutting lines 13 in the Y-axis direction.

[0085] In this manner, the workpiece 11 is cut along all the lines to be cut 13 that are parallel to the one direction. Next, as shown in Fig. 7(B), the chuck table 16 is rotated 90 degrees, and the workpiece 11 is cut along all the lines to be cut 13 that are parallel to the other direction perpendicular to the one direction. Fig. 7(B) is a diagram showing the latter half of the second cutting step S50.

[0086] In this embodiment, the scrap chip containing region 17c, which has a weak adhesive force to the dicing tape 21, is removed in the first cutting step S40, so that the scrap chips 15a2, which tend to scatter, are removed in advance in the second cutting step S50. Therefore, scattering of the scrap chips 15a2 can be suppressed without forming an uncut region.

[0087] Next, a second embodiment will be described. Fig. 8 is an enlarged cross-sectional view of an outer circumferential region 17b of a workpiece 31 according to the second embodiment. The workpiece 31 in the second embodiment is a semiconductor wafer before the back surface 11b side is ground.

[0088] The workpiece 31 is in a state before being thinned by grinding, polishing, or the like, and has a chamfered portion 11f formed on each outer periphery of the front surface 11a and the back surface 11b. As described above, the chamfered portion 11f is an area that has low adhesion to the dicing tape 21. This point is different from the workpiece 11 described above, but other points are the same as the workpiece 11.

[0089] When cutting the workpiece 31 according to the cutting method shown in Fig. 2, the end chip containing area identifying step S30 is omitted, and the length L2 from the outer peripheral edge 11d to the inner peripheral end of the chamfered portion 11f (i.e., the cutting area) is input by the operator to the control unit. The other points are the same as those in the first embodiment.

[0090] In the second embodiment, the scrap chip containing region 17c having a weak adhesive force to the dicing tape 21 is removed in the first cutting step S40, so that the scrap chips 15a2 that tend to scatter are removed in advance in the second cutting step S50. Therefore, scattering of the scrap chips 15a2 can be suppressed without forming an uncut region.

[0091] In addition, the structures, methods, etc. according to the above-described embodiments can be modified as appropriate without departing from the scope of the present invention. For example, the thickness of the cutting edge of the first cutting blade 44a can be made the same as the thickness of the cutting edge of the second cutting blade 44b.

[0092] As long as each step can be appropriately performed, the first cutting blade 44a and the second cutting blade 44b may be of a hubless type (washer type) or a hub type. [Explanation of symbols]

[0093] 2: Cutting device, 4: Base, 4a, 4b, 4c: Opening 8: Cassette support, 10: Cassette 11: Workpiece, 11a: Front surface, 11b: Back surface, 11b1: Covered area, 11b2: Exposed area 11c: side surface, 11d: outer periphery, 11e: circumscribed circle, 11f: chamfered portion 12: Table cover, 14: Accordion cover 16: chuck table, 16a: holding surface, 16b: clamp 18: guide rail, 20: support structure 13: cutting line, 15: device, 15a1, 15a2: scrap chips 17a: device region, 17b: peripheral region, 17c: scrap chip-containing region 19: passivation film, 21: dicing tape, 23: frame 25: Workpiece unit, 31: Workpiece 22: guide rail, 24a, 24b: Y-axis moving plate, 26a, 26b: ball screw 28a: driving source, 30a, 30b: guide rails, 32a, 32b: Z-axis moving plate 34a, 34b: ball screws, 36a, 36b: driving sources 38a: first cutting unit, 38b: second cutting unit 40a, 40b: spindle housing 42a: first spindle, 42b: second spindle 44a: first cutting blade, 44b: second cutting blade 46a, 46b: camera unit, 48: spinner cleaning unit, L1, L2: length

Claims

1. A cutting method for cutting a workpiece having a device region on a front surface side, the device region being partitioned by a plurality of cutting lines set in a lattice pattern, and a peripheral region surrounding the device region on the front surface side, the method comprising the steps of: A bonding step of bonding a dicing tape to the back side of the workpiece; a holding step of holding the workpiece on a holding table via the dicing tape after the attaching step; a first cutting step of removing a predetermined length of an offcut chip-containing region from the outer periphery of the outer periphery by rotating the holding table while cutting the first cutting blade into the outer periphery of the workpiece to a depth where the lower end of the first cutting blade reaches the dicing tape after the holding step; a second cutting step of cutting the workpiece along each of the planned cutting lines while cutting the workpiece with the second cutting blade into the workpiece to a depth such that a lower end of the second cutting blade reaches the dicing tape after the first cutting step; A cutting method comprising:

2. In the first cutting step, the offcut chip-containing region is removed using a first cutting unit having a first spindle and a first cutting blade attached to the first spindle; The cutting method according to claim 1, characterized in that in the second cutting step, the workpiece is cut along each intended cutting line using a second cutting unit having a second spindle and a second cutting blade having a thinner cutting edge than the first cutting blade attached to the second spindle.

Images