Method and apparatus for dividing wafers

Abstract

This technology ensures reliable separation of the metal film in wafer splitting processes for wafers with a metal film. It also prevents chipping of the chips during wafer splitting processes for wafers without a metal film. [Solution] A wafer splitting method for splitting a wafer (2) having a linear splitting starting point (5), comprising: a sheet attachment step of attaching a sheet (4) to the wafer; a clamping step of clamping the wafer along the splitting starting point with two elongated clamping bars (21, 50) parallel to the splitting starting point; a crack forming step of pressing a pressing position horizontally away from the clamping bars with an elongated pressing bar (22) parallel to the splitting starting point to form a crack (8) from the splitting starting point to the front or back surface; and a chip forming step of expanding the sheet in the radial direction of the wafer where the crack has been formed to create a gap in the crack and form a chip.

Description

Technical Field

[0001] The present invention relates to a wafer dividing method and a dividing apparatus.

Background Art

[0002] As disclosed in Patent Document 1 and Patent Document 2, when dividing a wafer having a metal film formed on the surface, the wafer may not be completely divided due to the ductility of the metal film. As a countermeasure, as disclosed in Patent Document 3, a technology has been proposed in which the front surface side and the back surface side of the wafer are sandwiched, and a pressing position distant from the sandwiched position is pressed by a pressing bar to divide the wafer provided with the metal film.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of Invention

Problems to be Solved by the Invention

[0004] However, even when wafer division is performed by the method as described in Patent Document 3, the division may be incomplete due to the ductility of the metal film.

[0005] Further, as in Patent Document 4, in a wafer not provided with a metal film, the divided chips may come into contact with each other, causing chipping of the outer edges of the chips.

[0006] Therefore, when splitting wafers with a metal film, there is the challenge of completely separating the metal film. Furthermore, when splitting wafers without a metal film, there is the challenge of preventing chipping. [Means for solving the problem]

[0007] One aspect of the present invention is a method for dividing a wafer having a linear dividing point at the dividing point, comprising: a sheet attachment step of attaching a sheet to one side of the wafer; a clamping step of clamping the wafer along the dividing point with two elongated clamping bars parallel to the dividing point; a crack forming step of pressing a pressing position horizontally away from the clamping bars with an elongated pressing bar parallel to the dividing point to form a crack extending from the dividing point to the front or back surface; and a chip forming step of expanding the sheet in the radial direction of the wafer where the crack has been formed to create a gap in the crack and form a chip.

[0008] The wafer may have a metal film on one of its surfaces.

[0009] The chip formation process may begin with a cooling step to cool the wafer.

[0010] One aspect of the present invention is a splitting apparatus for splitting a wafer in a workset in which a sheet is attached to one side of the wafer and a ring frame and integrated, the wafer having a linear splitting starting point, at the splitting starting point, comprising: a first clamping bar that abuts against the other side of the wafer; a second clamping bar that faces the first clamping bar and abuts against the one side of the wafer; a clamping mechanism that moves the first clamping bar and the second clamping bar closer to or further apart from each other in a direction perpendicular to the wafer plane direction to clamp the wafer along the splitting starting point; and from the first clamping bar and the second clamping bar that are clamping the wafer in the direction of the wafer plane The device comprises: a pressing bar parallel to the splitting starting point for pressing the wafer at a distance; a crack forming mechanism that moves the pressing bar in a direction perpendicular to the wafer plane direction to form a crack in the wafer at the splitting starting point; a spacing adjustment mechanism that adjusts the distance between the first clamping bar, the second clamping bar and the pressing bar in the wafer plane direction; an expansion mechanism that expands the sheet attached to the ring frame in the radial direction of the wafer; and a fixing mechanism that thermally shrinks the sheet between the outer circumference of the wafer and the inner circumference of the ring frame to fix the portion of the sheet attached to the wafer in an expanded state.

[0011] The wafer may be provided with a cooling mechanism for cooling it. [Effects of the Invention]

[0012] According to the above embodiments, in the wafer splitting process of a wafer equipped with a metal film, the metal film can be completely separated. Furthermore, in the wafer splitting process of a wafer without a metal film, chipping of the chips can be prevented. [Brief explanation of the drawing]

[0013] [Figure 1] This is a perspective view of the dividing device. [Figure 2] This is a perspective view of the splitting device with the holding table positioned below the heater. [Figure 3] This is a perspective view of the second clamping bar unit. [Figure 4] This diagram shows the workpiece holding process. [Figure 5] It is a diagram showing the clamping step. [Figure 6] It is a diagram showing the crack forming step. [Figure 7] It is a diagram showing the state of the wafer after the crack forming step. [Figure 8] It is a diagram showing the chip forming step. [Figure 9] It is a diagram showing the fixing step. [Figure 10] It is a diagram showing the fixing step. [Figure 11] It is a perspective view showing the configuration of the cooling mechanism. [Figure 12] It is a diagram showing a modified example of the cooling mechanism. [Mode for Carrying Out the Invention]

[0014] Hereinafter, the wafer dividing method and the dividing apparatus according to the present embodiment will be described with reference to the accompanying drawings. The present embodiment is applied to a case where the wafer 2 is divided in a work set 1 in which a sheet 4 is adhered to and integrated with the wafer 2 and a ring frame 3. In the work set 1, the flexible sheet 4 is arranged between the outer periphery of the wafer 2 and the inner periphery of the ring frame 3. As shown in Figure 2, a plurality of linear division starting points 5 are formed on the wafer 2, and the wafer 2 is divided along the division starting points 5.

[0015] Note that although the wafer 2 shown in Figure 2 has the division starting points 5 extending in the X-axis direction, the form of the division starting points of the wafer to be divided by the dividing method and the dividing apparatus of the present disclosure is not limited to the example in Figure 2. For example, a wafer having grid-shaped division starting points extending in the X-axis direction and the Y-axis direction may be the target of division.

[0016] As shown in Figures 4 to 10, the splitting starting point 5 is a bottomed groove (half-cut groove) formed on the surface Wa (the other side) of the wafer 2. Devices 6 are formed between multiple splitting starting points 5 on the surface Wa side of the wafer 2. A metal film 7 is provided on the back Wb (one side) of the wafer 2. The sheet 4 is attached to the back Wb side of the wafer 2. In other words, the wafer 2 is attached to the sheet 4 via the metal film 7. Note that, in addition to being formed by a cutting blade as described later, the bottomed groove may also be formed by ablation by irradiating the wafer 2 with a laser beam containing an absorbing wavelength.

[0017] The splitting apparatus 10, whose overall structure is shown in Figures 1 and 2, is a processing apparatus for splitting the wafer 2 of the workset 1 along the splitting starting point 5 to form multiple chips 9 (Figures 8 to 10). The X-axis, Y-axis, and Z-axis directions shown in each figure are perpendicular to each other, with the X-axis and Y-axis directions being horizontal and the Z-axis direction being vertical.

[0018] The splitting device 10 is equipped with a holding table 12 on its base 11 for holding the work set 1. The holding table 12 is cylindrical, and a through-hole 13 extending in the Z-axis direction is formed in the center of the holding table 12. As shown in Figures 4 to 10, the ring frame 3 is held on the upper surface of the holding table 12 around the through-hole 13 via a sheet 4, and the work set 1 is attached to the holding table 12 such that the wafer 2 is positioned above the through-hole 13. Multiple (four in this embodiment) clamping parts 14 are provided on the outer circumference of the holding table 12. Each clamping part 14 can be opened and closed relative to the holding table 12, and the ring frame 3 and the outer circumference of the sheet 4 are clamped and fixed between each clamping part 14 and the upper surface of the holding table 12 in the Z-axis direction.

[0019] The splitting device 10 includes an indexing mechanism 15 for moving the holding table 12 in the Y-axis direction. The indexing mechanism 15 has a pair of guide rails 16 mounted on a base 11 and extending in the Y-axis direction, a ball screw 18 extending in the X-axis direction and rotated by a motor 17, and a base 19 that supports the holding table 12. The base 19 is supported so as to be movable in the X-axis direction via the pair of guide rails 16, and the ball screw 18 is screwed into a nut portion 20 provided on the base 19. By rotating the ball screw 18 with the motor 17, the base 19 moves in the Y-axis direction along the guide rails 16, and this movement of the base 19 changes the position of the holding table 12 in the Y-axis direction.

[0020] The splitting device 10 includes a first clamping bar 21 and a pressing bar 22 located above the wafer 2, and a second clamping bar unit 23 located below the wafer 2, while the work set 1 is held on the holding table 12.

[0021] As shown in Figures 1 and 2, the first clamping bar 21 and the pressing bar 22 are supported on a gate-shaped column 25 provided on a base 11, and are movable in the Z-axis direction via a pressing bar lifting mechanism 26. The first clamping bar 21 and the pressing bar 22 are elongated members that extend in the X-axis direction parallel to the splitting starting point 5 of the wafer 2.

[0022] The pressing bar lifting mechanism 26 includes a support plate 27 attached to the column 25, a pair of guide rails 28 provided on the support plate 27 and extending in the Z-axis direction, a ball screw 30 extending in the Z-axis direction and rotated by a motor 29, and a lifting plate 31 that supports the first clamping bar 21 and the pressing bar 22. The lifting plate 31 is supported so as to be movable in the Z-axis direction via the pair of guide rails 28, and the ball screw 30 is screwed into a nut portion (not shown) provided on the lifting plate 31. By rotating the ball screw 30 with the motor 29, the lifting plate 31 moves in the Z-axis direction along the guide rails 28, and this movement of the lifting plate 31 changes the positions of the first clamping bar 21 and the pressing bar 22 in the Z-axis direction.

[0023] The lifting plate 31 has a vertical plate portion 311 extending in the Z-axis direction and a horizontal plate portion 312 extending in the horizontal direction. The vertical plate portion 311 is supported so as to be movable in the Z-axis direction relative to the guide rail 28.

[0024] As shown in Figures 4 to 6, the first clamping bar 21 is supported by a damper 32 on the horizontal plate portion 312 of the lifting plate 31. The damper 32 has a guide hole 33 formed in the horizontal plate portion 312 and penetrating in the Z-axis direction, a cylindrical spring housing portion 34 provided above the guide hole 33, and a coil spring 35 arranged inside the spring housing portion 34. The supported portion 211 at the top of the first clamping bar 21 is inserted into the spring housing portion 34 through the guide hole 33 and is in contact with the coil spring 35. As the supported portion 211 slides in the Z-axis direction relative to the guide hole 33, the position of the first clamping bar 21 relative to the lifting plate 31 changes in the Z-axis direction. The coil spring 35 elastically deforms to absorb the Z-axis load acting on the first clamping bar 21. Furthermore, the damper 32 is not limited to a spring-type damper equipped with a coil spring 35, but may also be an air damper or oil damper that absorbs the load using air pressure or hydraulic pressure.

[0025] As shown in Figures 4 to 6, the pressing bar 22 is supported on the horizontal plate portion 312 of the lifting plate 31 so as to be movable in the Y-axis direction via a spacing adjustment mechanism 36. The spacing adjustment mechanism 36 has a pair of guide rails 37 (Figures 1 and 2) provided on the horizontal plate portion 312 and extending in the Y-axis direction, and a ball screw 39 that extends in the Y-axis direction and is rotated by a motor 38. The upper supported portion 221 of the pressing bar 22 is supported so as to be movable in the Y-axis direction via the pair of guide rails 37, and the ball screw 39 is screwed into a nut portion 222 provided on the supported portion 221. By rotating the ball screw 39 with the motor 38, the pressing bar 22 moves in the Y-axis direction along the guide rails 37. This movement of the pressing bar 22 changes the distance between the first clamping bar 21 and the pressing bar 22 in the Y-axis direction. The spacing adjustment mechanism 36 is configured to adjust the spacing between the first clamping bar 21 and the second clamping bar 50 and the pressing bar 22 in the planar direction of the wafer 2.

[0026] The first clamping bar 21 extends downward from the supported portion 211, and the pressing bar 22 extends downward from the supported portion 221. With the workset 1 held on the holding table 12, the pressing bar lifting mechanism 26 lowers the lifting plate 31, causing the lower ends of the first clamping bar 21 and the pressing bar 22 to come into contact with the surface Wa side of the wafer 2.

[0027] As shown in Figures 4 to 6, the splitting device 10 includes a protective film supply mechanism 40 that supplies a protective film 41 between the first clamping bar 21 and the pressing bar 22 and the wafer 2. The protective film supply mechanism 40 includes a feeding unit 42, a winding unit 43, a first transport roller 44, and a second transport roller 45. The feeding unit 42 and the winding unit 43 are positioned to clamp the first clamping bar 21 and the pressing bar 22 in the Y-axis direction. The protective film 41 fed out from the feeding unit 42 is transported by the first transport roller 44, passes below the first clamping bar 21 and the pressing bar 22, and is transported by the second transport roller 45 to be wound into the winding unit 43. The lower ends of the first clamping bar 21 and the lower ends of the pressing bar 22 abut against the surface Wa side of the wafer 2 via the protective film 41.

[0028] As shown in Figure 3, the second clamping bar unit 23 is equipped with four second clamping bars 50 (501, 502, 503, and 504) of different lengths in the X-axis direction, and the second clamping bar 50 to be used is switched by the operation of the second clamping bar switching mechanism 51. Each of the four second clamping bars 50 (501, 502, 503, and 504) is in a working state facing the first clamping bar 21 with its tip facing upward. The second clamping bars 50 (501, 502, 503, and 504) are elongated members that extend in the X-axis direction parallel to the starting point 5 of the wafer 2's splitting.

[0029] As shown in Figure 3, the second clamping bar switching mechanism 51 includes a cylindrical support member 52 that is rotatably supported about an axis extending in the X-axis direction relative to the support bracket 54, and a motor 53 that rotates the support member 52. The four second clamping bars 50 (501, 502, 503, and 504) are arranged at equal intervals in the rotational direction of the support member 52 and protrude radially from the outer circumferential surface of the support member 52. By rotating the support member 52 with the motor 53, the orientation of the four second clamping bars 50 (501, 502, 503, and 504) is changed.

[0030] As shown in Figure 2, the second clamping bar unit 23 is positioned on the base 11 between a pair of guide rails 16 of the indexing mechanism 15 and below the first clamping bar 21 and the pressing bar 22. The second clamping bar unit 23 is supported on the base 11 so as to be movable in the Z-axis direction via the second clamping bar lifting mechanism 55 shown in Figure 3. The base 19 has an opening (not shown) into which the second clamping bar unit 23 can enter, and when the second clamping bar unit 23 is positioned within the through-hole 13 of the holding table 12 as shown in Figure 1, the second clamping bar unit 23 enters the opening in the base 19.

[0031] The second clamping bar lifting mechanism 55 includes a support plate 56 attached to the base 11, a pair of guide rails 57 provided on the support plate 56 and extending in the Z-axis direction, and a ball screw 59 extending in the Z-axis direction and rotated by a motor 58. A support bracket 54 is supported so as to be movable in the Z-axis direction via the pair of guide rails 57, and the ball screw 59 is screwed into a nut portion (not shown) provided on the support bracket 54. By rotating the ball screw 59 with the motor 58, the support bracket 54 moves in the Z-axis direction along the guide rails 57, and this movement of the support bracket 54 changes the position of the second clamping bar unit 23 in the Z-axis direction.

[0032] With the workset 1 held on the holding table 12, the support bracket 54 is raised by the second clamping bar lifting mechanism 55, causing the upper end of the second clamping bar 50 (any of the four second clamping bars 501, 502, 503, and 504) that protrudes upward from the support member 52 in the second clamping bar unit 23 to contact the back surface Wb side of the wafer 2. Since the back surface Wb side of the wafer 2 is provided with a metal film 7 and a sheet 4, the upper end of the second clamping bar 50 contacts the back surface Wb side of the wafer 2 via the metal film 7 and the sheet 4.

[0033] The splitting device 10 is equipped with a push-up ring 60 inside the through-hole 13 of the holding table 12 (see Figures 1, 2, 7 to 10). The push-up ring 60 is a ring-shaped member located below the sheet 4 between the outer circumference of the wafer 2 and the inner circumference of the ring frame 3 when the work set 1 is held on the holding table 12. The push-up ring 60 can be raised and lowered in the Z-axis direction by a push-up ring lifting mechanism 61 (Figures 2, 7 to 10).

[0034] The thrust-up ring lifting mechanism 61 comprises a housing 62 and a lifting section 63 that protrudes upward from the housing 62 and is movable in the Z-axis direction. The upper end of the lifting section 63 is connected to a connecting section 601 provided on the inner circumference of the thrust-up ring 60. The thrust-up ring lifting mechanism 61 is configured, for example, by an air cylinder. In the case of an air cylinder, the housing 62 is the cylinder and the lifting section 63 is the piston, and the lifting operation of the lifting section 63 is performed by air supplied to the inside of the housing 62. The thrust-up ring lifting mechanism 61 may also be an electric actuator other than an air cylinder.

[0035] The splitting device 10 is equipped with a heater 70 (see Figures 1, 2, 9, and 10). The heater 70 is supported on the base 11 via a heater lifting mechanism 71 and a heater rotation mechanism 72. The heater 70 is equipped with a heat source (not shown) and blows hot air downward.

[0036] The heater lifting mechanism 71 moves the heater 70 in the Z-axis direction. As shown in Figures 1 and 2, the heater lifting mechanism 71 has a housing 73 and a lifting section 74 that protrudes upward from the housing 73 and is movable in the Z-axis direction, with the lifting section 74 supporting the heater 70 via a heater rotation mechanism 72. The heater lifting mechanism 71 is configured, for example, by an air cylinder. In the case of an air cylinder, the housing 73 is a cylinder and the lifting section 74 is a piston, and the lifting operation of the lifting section 74 is performed by air supplied to the inside of the housing 73. Note that the heater lifting mechanism 71 may also be an electric actuator other than an air cylinder.

[0037] As shown in Figures 1 and 2, the heater rotation mechanism 72 has a support plate 77 rotated by a motor 76 at the tip of a support arm 75 extending in the X-axis direction from the upper end of the lifting section 74, and a pair of heaters 70 are supported at both ends of the support plate 77. The support plate 77 extends horizontally, and the distance between the pair of heaters 70 in the horizontal direction is greater than the diameter of the wafer 2 and smaller than the diameter of the ring frame 3.

[0038] The heater 70 is positioned away from the first clamping bar 21 and the pressing bar 22 in the Y-axis direction. As shown in Figure 2, the index moving mechanism 15 can be operated to move the holding table 12 in the Y-axis direction, positioning the holding table 12 below the heater 70. With the workset 1 held on the holding table 12, hot air can be blown downward from the pair of heaters 70 to apply hot air to the sheet 4 between the outer circumference of the wafer 2 and the inner circumference of the ring frame 3 in the workset 1 (see Figures 9 and 10).

[0039] The splitting device 10 is further equipped with a cooling mechanism 80 (see Figures 7 to 11). As shown in Figures 7 to 10, the cooling mechanism 80 is located inside the push-up ring 60. As shown in Figure 11, the cooling mechanism 80 has a plurality of air blowing nozzles 82 provided at predetermined intervals in the X-axis direction on the upper surface of a housing 81 that extends in the X-axis direction. Cold air sent from a cold air source 83 passes through a flow path (not shown) inside the housing 81, and cold air is ejected upward from each air blowing nozzle 82. This cold air can cool the work set 1. More specifically, it can cool the wafer 2 held above the penetration portion 13 of the holding table 12, thereby reducing the ductility of the metal film 7. It also cools the sheet 4 to which the wafer 2 is attached.

[0040] Each part of the splitting device 10 is controlled by the control unit 90 (Figures 1 and 2). The operations described below are performed by the processor of the control unit 90 performing calculations according to a program stored in the memory of the control unit 90 and sending control signals to each part of the splitting device 10.

[0041] Next, we will explain each step of the wafer splitting method performed by the splitting device 10.

[0042] [Sheet application process] In the sheet bonding process, sheet 4 is bonded to the back surface Wb of wafer 2. The area of ​​sheet 4 is larger than the area of ​​wafer 2, and the outer portion of sheet 4 that extends beyond the outer edge of wafer 2 is bonded to the ring frame 3. In other words, sheet 4 is bonded to wafer 2 and ring frame 3 to form an integrated workset 1. The formation of workset 1 is performed by a separate device from the splitting device 10, and the completed workset 1 is transported to the splitting device 10.

[0043] As shown in Figure 2, a linear splitting starting point 5 is formed on the wafer 2 before it is transported to the splitting device 10. The splitting starting point 5 may be formed after the workset 1 is formed, or it may be formed on the wafer 2 before the workset 1 is formed. As an example of a method for forming the splitting starting point 5, cutting is performed using a cutting device separate from the splitting device 10, and the cutting blade is driven into the surface Wa side of the wafer 2 to a predetermined depth to form a bottomed groove.

[0044] [Workset holding process] The first step in the splitting apparatus 10 is the work set holding step. In the work set holding step, the work set 1 is held on the holding table 12. As shown in Figure 4, the ring frame 3 and the outer periphery of the sheet 4 are placed on the upper surface of the holding table 12, and the ring frame 3 is fixed from above by the clamp part 14. The wafer 2 is supported only by the sheet 4 above the through-hole 13 of the holding table 12 (it is floating without being directly supported by the holding table 12).

[0045] [Holding process] Next, the clamping process is performed. In the clamping process, as shown in Figure 5, the wafer 2 is clamped along the splitting starting point 5 by a long first clamping bar 21 and a second clamping bar 50 that are parallel to the splitting starting point 5 of the wafer 2.

[0046] At the beginning of the clamping process, the control unit 90 operates the index movement mechanism 15 to adjust the position of the workset 1 in the Y-axis direction, positioning the wafer 2 in a position suitable for clamping by the first clamping bar 21 and the second clamping bar 50. Specifically, the clamping position is set so that the area near the splitting initiation point 5 of the location to be cracked 8 in the next crack formation process is clamped by the lower end of the first clamping bar 21 and the upper end of the second clamping bar 50.

[0047] The control unit 90 selects the second clamping bar 50 of the optimal length from the four second clamping bars 50 (501, 502, 503, and 504) according to the length of the wafer 2 in the X-axis direction at the location to be clamped. For example, the shortest second clamping bar 501 is positioned opposite the first clamping bar 21 at the location near both ends of the wafer 2 in the Y-axis direction, as this is the region where the length of the wafer 2 in the X-axis direction is shortest. The longest second clamping bar 504 is positioned opposite the first clamping bar 21 at the location near the center of the wafer 2 in the Y-axis direction, as this is the region where the length of the wafer 2 in the X-axis direction is longest. At the middle of the wafer 2 in the Y-axis direction, either the third longest second clamping bar 502 or the second longest second clamping bar 503 is positioned opposite the first clamping bar 21, depending on the length of the wafer 2 in the X-axis direction. The example shown in Figure 5 shows the case where the shortest second clamping bar 501 is selected and positioned upwards.

[0048] Once the control unit 90 has selected a second clamping bar 50 to face the first clamping bar 21, it operates the second clamping bar switching mechanism 51 to orient the selected second clamping bar 50 upward relative to the support member 52. Furthermore, the control unit 90 operates the second clamping bar lifting mechanism 55 to raise the second clamping bar unit 23. When the second clamping bar unit 23 has risen by a predetermined amount, the upper end of the second clamping bar 50 (second clamping bar 501 in the example of Figure 5) comes into contact with the back surface Wb side of the wafer 2 via the sheet 4. As shown in Figure 5, the second clamping bar 50 supports the wafer 2 from below while being pushed up above the position where the holding table 12 holds the sheet 4 and the ring frame 3. In this state, a predetermined tension is applied to the sheet 4.

[0049] Next, the control unit 90 operates the pressing bar lifting mechanism 26 to lower the first clamping bar 21 together with the pressing bar 22. When the first clamping bar 21 has descended by a predetermined amount, the lower end of the first clamping bar 21 comes into contact with the surface Wa side of the wafer 2 via the protective film 41. In this state, the wafer 2 is lifted by the second clamping bar 50, which has been raised by operating the lower second clamping bar lifting mechanism 55 to raise the second clamping bar unit 23. Since the second clamping bar 50 is facing below the first clamping bar 21, the descent of the first clamping bar 21 is restricted after the lower end of the first clamping bar 21 comes into contact with the surface Wa side of the wafer 2 via the protective film 41. The load in the Z-axis direction acting on the first clamping bar 21 is absorbed by the damper 32 (spring, air pressure, hydraulic pressure), and the state in which the first clamping bar 21 comes into contact with the surface Wa side of the wafer 2 is maintained. In other words, the position of the first clamping bar 21 in the Z-axis direction is controlled by the pressing bar lifting mechanism 26 and the damper 32.

[0050] In this way, during the clamping process, the wafer 2 is clamped from above and below by the first clamping bar 21 and the second clamping bar 50 in the region along the splitting starting point 5 of the wafer 2. The pressing bar lifting mechanism 26 and damper 32, which are involved in the position control of the first clamping bar 21 in the Z-axis direction, and the second clamping bar lifting mechanism 55, which is involved in the position control of the second clamping bar 50 in the Z-axis direction, constitute a clamping mechanism that moves the first clamping bar 21 and the second clamping bar 50 closer to or further apart from each other in a direction perpendicular to the plane direction of the wafer 2 (Z-axis direction), thereby clamping the wafer 2 along the splitting starting point 5.

[0051] [Crack formation process] Next, a crack formation process is performed. In the crack formation process, as shown in Figure 6, the wafer 2 is pressed by a long pressing bar 22 that is parallel to the splitting starting point 5 at a pressing position horizontally away from the first and second clamping bars 21 and 50 that hold the wafer 2.

[0052] Before performing the crack formation process, the control unit 90 operates the spacing adjustment mechanism 36 to set the optimal spacing of the pressing bar 22 relative to the first clamping bar 21 in the Y-axis direction. For example, in the embodiment shown in Figures 4 to 6, the pressing position by the pressing bar 22 is between the first division starting point 5 (the leftmost division starting point 5 in Figure 6) where the crack 8 was formed in the previous crack formation process and the second division starting point 5 (the division starting point 5 located midway in the left-right direction in Figure 6) where the crack 8 will be formed in the current crack formation process, and is set to be closer to the first division starting point 5 than to the second division starting point 5. Furthermore, the pressing position by the pressing bar 22 is set to avoid the area where the device 6 is formed.

[0053] When pressing the wafer 2 with the pressing bar 22, the control unit 90 operates the pressing bar lifting mechanism 26 in the direction of lowering the lifting plate 31. The pressing bar 22 has descended together with the first clamping bar 21 in the clamping process performed earlier, and the lower end of the pressing bar 22 is in a state close to the surface Wa of the wafer 2. When the pressing bar lifting mechanism 26 is operated from this state in the direction of lowering the lifting plate 31, the lower end of the pressing bar 22 presses the surface Wa side of the wafer 2 via the protective film 41.

[0054] At this time, at the pressing position where the pressing bar 22 presses against the wafer 2, the wafer 2 is pushed downward. On the other hand, at the point where the wafer 2 is held vertically by the first clamping bar 21 and the second clamping bar 50, the downward movement of the wafer 2 is restricted, and a reaction force acts to push up the first clamping bar 21. This reaction force is absorbed by the damper 32. As a result of these forces acting, a crack 8 is formed from the splitting starting point 5 near the point where the wafer 2 is held by the first clamping bar 21 and the second clamping bar 50 toward the back surface Wb of the wafer 2. The crack 8 is also formed in the metal film 7.

[0055] When pressing the wafer 2 with the pressing bar 22, the surface Wa side of the wafer 2 is covered with the protective film 41, which prevents damage to the wafer 2 by the first clamping bar 21, adhesion of foreign matter to the wafer 2, and scattering of fragments generated from the wafer 2 when a crack 8 is formed. Therefore, the wafer 2 is protected, and the crack formation process can be performed in a clean state without processing debris adhering to the device 6, etc.

[0056] In this embodiment, a crack 8 is formed from the splitting point 5 on the surface Wa side of wafer 2 toward the back Wb side having the metal film 7, but the direction in which the crack is formed is not limited to this. For example, a splitting point may be formed in the middle of the thickness of wafer 2, and a crack may be formed from this splitting point toward either the surface Wa side or the back Wb side. Alternatively, a splitting point may be formed on the back Wb side of wafer 2, and a crack may be formed from this splitting point toward the surface Wa side.

[0057] Thus, in the crack formation process, the pressing bar 22 presses at a pressing position horizontally away from the first clamping bar 21 and the second clamping bar 50, forming a crack that extends from the splitting initiation point to the surface Wa or back surface Wb of the wafer 2. The pressing bar lifting mechanism 26 constitutes a crack formation mechanism that moves the pressing bar 22 in a direction perpendicular to the plane direction of the wafer 2 to form a crack 8 in the wafer 2 at the splitting initiation point 5.

[0058] Once a crack 8 is formed along a single splitting starting point 5 extending in the X-axis direction, the control unit 90 operates the index moving mechanism 15 to move the holding table 12 in the Y-axis direction, positioning the workpiece set 1 so that the first clamping bar 21 and the second clamping bar 50 clamp the workpiece set 1 near the next splitting starting point 5 where no crack 8 has yet formed. Then, the aforementioned clamping process and crack formation process are performed.

[0059] In conjunction with the movement of the holding table 12 due to the operation of the index moving mechanism 15, the protective film supply mechanism 40 may be used to feed out the protective film 41, and then a new protective film 41 may be supplied to the location where the crack 8 is to be formed.

[0060] In this way, while performing the index feeding operation (position adjustment in the Y-axis direction) of the workset 1 by the operation of the index moving mechanism 15, the clamping process and the crack formation process are repeated to sequentially form cracks 8 along the multiple splitting starting points 5 on the wafer 2, thereby forming cracks 8 along all of the splitting starting points 5.

[0061] [Cooling process] Next, a cooling process is performed. In the cooling process, the wafer 2 is cooled using the cooling mechanism 80 shown in Figure 11. The control unit 90 blows cold air sent from the cold air source 83 upward from multiple air nozzles 82. The cold air cools the wafer 2 held above the penetration portion 13 of the holding table 12, reducing the ductility of the metal film 7. The cold air also cools the sheet 4 to which the wafer 2 is attached, reducing the flexibility of the sheet 4.

[0062] The process may proceed to the next chip formation step without performing the cooling step. If the cooling step is not performed, the splitting device 10 may not be configured to include a cooling mechanism 80.

[0063] [Chip formation process (sheet expansion process)] Next, the chip formation process is performed. In the chip formation process, as shown in Figure 7, the control unit 90 releases the clamping of the wafer 2 by the first clamping bar 21 and the second clamping bar 50, and releases the pressure on the wafer 2 by the pressing bar 22.

[0064] In the first embodiment, the chip forming process may be performed with the holding table 12 positioned at the location where the crack forming process was performed (the position shown in Figure 1). In the second embodiment, the chip forming process may be performed after moving the holding table 12 from the location where the crack forming process was performed to a position below the heater 70 (the position shown in Figure 2). In the second embodiment, when performing the chip forming process, the control unit 90 operates the index movement mechanism 15 to move the holding table 12 holding the work set 1 in the Y-axis direction, positioning the work set 1 below the heater 70.

[0065] As shown in Figure 8, during the chip formation process, the control unit 90 operates the push-up ring lifting mechanism 61 to raise the push-up ring 60. When the push-up ring 60 rises, it pushes the sheet 4 upward between the outer circumference of the wafer 2 and the inner circumference of the ring frame 3. The outer circumference of the sheet 4 is fixed together with the ring frame 3 between the holding table 12 and the clamping portion 14. Therefore, the sheet 4, pushed up by the push-up ring 60, expands radially in the area where the wafer 2 is attached. When the sheet 4 expands in this way, it forms gaps in the cracks 8, and the wafer 2 is divided into individual chips 9.

[0066] If a cooling process is performed before the chip formation process to reduce the ductility of the metal film 7, expanding the sheet 4 makes it easier for cleavage to occur along the crack 8 at the location of the metal film 7, resulting in a more reliable gap formation in the crack 8. Furthermore, if the chip formation process is performed while the sheet 4 is cooled during the cooling process, the force is not absorbed by the flexible sheet 4 and is more easily transmitted to the wafer 2, thereby enhancing the effect of forming a gap in the crack 8.

[0067] Thus, in the chip formation process, the sheet 4 is expanded in the radial direction of the wafer 2 in which the crack 8 is formed, creating a gap in the crack 8 and forming a chip 9. The chip formation process may also be called the sheet expansion process. The push-up ring 60 and the push-up ring lifting mechanism 61 constitute an expansion mechanism that expands the sheet 4 attached to the ring frame 3 in the radial direction of the wafer 2.

[0068] [Fixed process] Next, the fixing process is performed. In the fixing process, the sheet 4 between the outer circumference of the wafer 2 and the inner circumference of the ring frame 3 is heat-shrunk, and the portion of the sheet 4 attached to the wafer 2 is fixed in an expanded state.

[0069] During the fixing process, the holding table 12 is positioned below the heater 70, as shown in Figure 2. If the holding table 12 is not positioned below the heater 70 during the fixing process, the control unit 90 operates the index movement mechanism 15 to move the holding table 12 in the Y-axis direction, positioning it below the heater 70. In particular, as shown in Figure 9, the pair of heaters 70 provided at both ends of the support plate 77 are set to be positioned above the sheet 4 between the outer circumference of the wafer 2 and the inner circumference of the ring frame 3.

[0070] Although Figure 2 shows the work set 1 removed from the holding table 12, the fixing process begins with the work set 1 held on the holding table 12 and the sheet 4 pushed up by the push-up ring 60 (as shown in Figure 9).

[0071] Figures 9 and 10 show the state during the fixing process. As shown in Figure 9, the control unit 90 operates the heater lifting mechanism 71 to bring a pair of heaters 70 closer to the sheet 4 on the holding table 12 in the Z-axis direction, and blows hot air from each heater 70 onto the sheet 4. The sheet 4 shrinks in the areas where the hot air is blown. The control unit 90 operates the heater rotation mechanism 72 to rotate the support plate 77 so that the hot air blows onto the sheet 4 along the entire circumferential direction between the outer circumference of the wafer 2 and the inner circumference of the ring frame 3.

[0072] As shown in Figure 10, when the sheet 4 is thermally shrunk, the control unit 90 operates the push-up ring lifting mechanism 61 to lower the push-up ring 60, and simultaneously operates the heater lifting mechanism 71 to lower the heater 70. As a result, the sheet 4 between the outer circumference of the wafer 2 and the inner circumference of the ring frame 3 is thermally shrunk, eliminating any slack, while the sheet 4 attached to the wafer 2 maintains the expanded state achieved in the previous chip formation process. Therefore, even when the push-up of the sheet 4 by the push-up ring 60 is released, the state in which the wafer 2 is divided into individual chips 9 by forming gaps in the cracks 8 is maintained.

[0073] In this way, the fixing process involves thermally shrinking the sheet 4, fixing the portion of the sheet 4 attached to the wafer 2 in an expanded state, and maintaining the wafer 2 in a state divided into individual chips 9. The heater 70, the heater lifting mechanism 71 and heater rotation mechanism 72 that operate the heater 70 constitute a fixing mechanism that thermally shrinks the sheet 4 between the outer circumference of the wafer 2 and the inner circumference of the ring frame 3, fixing the portion of the sheet 4 attached to the wafer 2 in an expanded state.

[0074] The wafer 2 is divided in the dividing apparatus 10 of this embodiment by each of the steps described above. In the dividing process of a wafer 2 having a metal film 7, it may be difficult to divide it completely due to the high ductility of the metal film 7. In the dividing method and dividing apparatus 10 of this embodiment, the wafer 2 is held between the first clamping bar 21 and the second clamping bar 50 and pressed by the pressing bar 22 to form a crack 8 extending from the dividing starting point 5. Then, the sheet 4 attached to the wafer 2 is expanded in the radial direction of the wafer 2 to form a gap in the crack 8, thereby completely dividing the metal film 7 and reliably dividing the wafer 2 having the metal film 7 along the dividing starting point 5.

[0075] Therefore, by applying the technology of this disclosure, productivity can be improved when manufacturing multiple chips 9 from a wafer 2. Furthermore, because the wafer 2 has excellent divisibility when manufacturing chips 9, burrs generated at the division points of the metal film 7 can be suppressed, and high-quality chips 9 can be obtained. In addition, the effort required for post-processing (such as burr removal) after wafer 2 has been divided can be reduced.

[0076] In this embodiment, a cooling step is performed to cool the wafer 2 at the beginning of the chip formation process, but a cooling step may also be performed to cool the wafer 2 before the crack formation process. Cooling the wafer 2 reduces the ductility of the metal film 7, which has the effect of making it easier to form cracks 8 in the wafer 2 containing the metal film 7 during the crack formation process. The cooling mechanism 80, which is positioned inside the push-up ring 60 and cools the wafer 2 from below, can easily cool the wafer 2 even before the crack formation process is performed.

[0077] Figure 12 shows a modified cooling mechanism 85, which has a different layout from the cooling mechanism 80 shown in Figures 7 to 10. This modified cooling mechanism 85 is positioned above the wafer 2 held on the holding table 12.

[0078] The cooling mechanism 85 has multiple air blowing nozzles 87 provided at predetermined intervals on the lower side of the housing 86. Cold air sent from the cold air source 88 passes through the flow path 89 inside the housing 86, and cold air is blown downward from each air blowing nozzle 87. This cold air can cool the wafer 2 of the workset 1. Even in a configuration where the cooling mechanism 85 is positioned above the wafer 2, it is possible to cool the metal film 7 or sheet 4 through the wafer 2.

[0079] The configuration in which the cooling mechanism 85 is placed above the wafer 2 has the advantage of being less constrained by installation space compared to the cooling mechanism 80 which is placed inside the push-up ring 60. For example, unlike the housing 81 of the cooling mechanism 80 shown in Figure 11, the housing 86 of the cooling mechanism 85 can be made circular in shape to correspond to the size of the wafer 2, creating a structure that directs cool air over a wide area onto the wafer 2.

[0080] The cooling mechanism 85 can be installed, for example, in the splitting device 10 shown in Figures 1 and 2, between the installation positions of the first clamping bar 21 and the pressing bar 22 and the installation position of the heater 70 in the Y-axis direction. In such a device layout, after performing the clamping process and the crack formation process using the first clamping bar 21, the pressing bar 22 and the second clamping bar 50, the holding table 12 is moved in the Y-axis direction to position it below the cooling mechanism 85 to perform the cooling process and the chip formation process, and then the holding table 12 is moved further in the Y-axis direction to position it below the heater 70 to perform the fixing process. Alternatively, only the cooling process may be performed with the holding table 12 positioned below the cooling mechanism 85, and the chip formation process and the fixing process may be performed with the holding table 12 positioned below the heater 70.

[0081] Not limited to the modifications of the cooling mechanism described above, different structures, operations, and methods from the illustrated embodiments can be applied without departing from the spirit of the invention.

[0082] In the illustrated embodiment, the splitting starting point 5 is formed by a bottomed groove (half-cut groove) formed on the surface Wa side of the wafer 2, but the splitting starting point in the present disclosure is not limited to this form. For example, a laser beam may be irradiated to concentrate inside the wafer 2 to form a modified area inside the wafer 2, and this modified area may be used as the splitting starting point.

[0083] In the illustrated embodiment, the sheet 4 is pushed up and expanded by a cylindrical push-up ring 60 during the chip formation process, but the sheet expansion in the present invention is not limited to this form. For example, the sheet may be expanded by applying an expansion mechanism that grips the outer periphery of the sheet and pulls it to expand it in the radial direction of the wafer.

[0084] The wafer splitting apparatus 10 in the illustrated embodiment includes a clamping mechanism and a crack formation mechanism used in the clamping process and the crack formation process, and an expansion mechanism used in the chip formation process. However, depending on the method of wafer splitting, each process may be divided and carried out by multiple apparatuses. For example, the clamping process and the crack formation process may be carried out by a braking apparatus equipped with a clamping mechanism and a crack formation mechanism, and the chip formation process may be carried out by an expander equipped with an expansion mechanism.

[0085] The illustrated embodiment applies the splitting method and splitting apparatus of this disclosure to the splitting of a wafer with a metal film, but it can also be applied to the splitting of a wafer without a metal film. When splitting a wafer without a metal film, if the splitting is incomplete, the outer edges of adjacent chips may chip due to contact with each other or other reasons. In such cases, by applying the technology related to the splitting method and splitting apparatus of this disclosure described above, the wafer can be completely split and chipping of the chips can be prevented.

[0086] Furthermore, the embodiments of the present invention are not limited to the embodiments and modifications described above, and may be modified, substituted, or altered in various ways without departing from the spirit of the technical idea of ​​the present invention. Moreover, if the technical idea of ​​the present invention can be realized in a different way by advances in the art or by other derived arts, it may be implemented by that method. Accordingly, the claims cover all embodiments that may fall within the scope of the technical idea of ​​the present invention. [Industrial applicability]

[0087] By applying the technology disclosed herein, reliable wafer splitting can be achieved. In particular, it is possible to completely split the metal film on wafers equipped with a metal film, contributing to improved productivity when manufacturing various devices by splitting this type of wafer. [Explanation of Symbols]

[0088] 1: Workset 2: Wafer 3: Ring frame 4: Sheet 5: Split starting point 6: Devices 7: Metal film 8: Crack 9: Tip 10:Dividing device 11: Base 12: Holding Table 13: Penetration 14: Clamp section 15: Index Movement Mechanism 21: First clamping bar 22: Pressure bar 23: Second clamping bar unit 26: Pressure bar lifting mechanism (clamping mechanism, crack formation mechanism) 31: Lifting plate 32: Damper (clamping mechanism) 36: Spacing adjustment mechanism 40: Protective film supply mechanism 41: Protective film 50: Second clamping bar 51: Second clamping bar switching mechanism 55: Second clamping bar lifting mechanism (clamping mechanism) 60: Push-up ring (expansion mechanism) 61: Push-up ring lifting mechanism (expansion mechanism) 70: Heater (fixed mechanism) 71: Heater lifting mechanism (fixing mechanism) 72: Heater rotation mechanism (fixed mechanism) 80: Cooling mechanism 85: Cooling mechanism 90: Control Unit Wa: The surface (the other side) of the wafer. Wb: Back side of the wafer (one side)

Claims

1. A method for dividing a wafer having a linear division starting point, wherein the wafer is divided at the division starting point, A sheet attachment step of attaching a sheet to one side of the wafer, A clamping step in which the wafer is clamped along the starting point of the splitting using two elongated clamping bars parallel to the starting point of the splitting, A crack formation step involves pressing a pressing position horizontally away from the clamping bar with a long pressing bar parallel to the splitting point to form a crack extending from the splitting point to the surface or back surface, A chip forming step involves expanding the sheet in the radial direction of the wafer in which the crack is formed, thereby creating a gap in the crack and forming a chip, A method for splitting a wafer, including [specific details omitted].

2. The wafer splitting method according to claim 1, wherein the wafer has a metal film on one of its surfaces.

3. A method for splitting a wafer according to claim 1 or 2, comprising a cooling step of cooling the wafer at the beginning of the chip formation step.

4. A splitting apparatus for splitting a wafer in a workset in which a sheet is attached to one side of the wafer and a ring frame, which has a linear splitting starting point, at the splitting starting point, A first clamping bar that contacts the other side of the wafer, A second clamping bar facing the first clamping bar and in contact with one side of the wafer, A clamping mechanism that moves the first clamping bar and the second clamping bar closer to or further apart from each other in a direction perpendicular to the plane direction of the wafer, and clamps the wafer along the starting point of the division, A pressing bar parallel to the splitting starting point that presses the wafer at a position away from the first clamping bar and the second clamping bar that holds the wafer in the plane direction of the wafer, A crack formation mechanism that moves the pressing bar in a direction perpendicular to the surface direction of the wafer to form a crack in the wafer at the splitting starting point, A spacing adjustment mechanism for adjusting the distance between the first clamping bar, the second clamping bar and the pressing bar in the planar direction of the wafer, An expansion mechanism for expanding the sheet attached to the ring frame in the radial direction of the wafer, A fixing mechanism that heat-shrinks the sheet between the outer circumference of the wafer and the inner circumference of the ring frame, thereby fixing the portion of the sheet attached to the wafer in an expanded state, A dividing device equipped with the following features.

5. The splitting apparatus according to claim 4, further comprising a cooling mechanism for cooling the wafer.

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