Wafer dividing method

Abstract

To divide a wafer excellently by roller breaking.SOLUTION: A wafer dividing method for dividing a wafer into a plurality of chips includes a holding step of holding, on a holding table 51, a wafer 10 which has a dividing starting point formed along a dividing scheduled line and has a dicing tape 18 attached thereto, and a dividing step of dividing the wafer 10 along the dividing starting point by moving a roller 52 relatively to the wafer 10 in a direction from the inside of the wafer 10 to the outside of the wafer 10 while pressing the wafer 10 via the dicing tape 18 by the roller 52 after the holding step. The dividing step includes a first dividing step and a second dividing step in which the roller 52 moves in different directions, respectively.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a method for dividing a wafer. [Background technology]

[0002] Roller breaking is known as a method for dividing a wafer having division starting points formed thereon, in which the wafer is divided by pressing the wafer with a roller via a protective tape attached to the wafer.

[0003] For example, Patent Document 1 describes dividing the wafer into chips by moving a roller relatively to the wafer from one end to the other end of the protective tape. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2023-032665 A Summary of the Invention [Problem to be solved by the invention]

[0005] By using the roller breaking described in Patent Document 1, the possibility of undivided regions occurring on the wafer can be significantly reduced compared to when the wafer is divided only by tape expanding.

[0006] However, even by roller breaking, undivided regions may occur, and further improvement is required. The present invention has been made in view of the above, and an object of the present invention is to divide a wafer well by roller breaking. [Means for solving the problem]

[0007] A wafer dividing method according to one embodiment of the present invention is a wafer dividing method for dividing a wafer to produce a plurality of chips, and includes a holding step of holding a wafer, the wafer having a dividing starting point formed along a planned dividing line and a protective tape attached thereto, on a holding table, and a dividing step of dividing the wafer along the dividing starting point by moving the roller relatively to the wafer from the inside to the outside of the wafer while pressing the wafer with a roller via the protective tape after the holding step, the dividing step including a first dividing step and a second dividing step in which the roller moves in different directions. Effect of the Invention

[0008] According to the present invention, the wafer can be divided well by roller breaking. [Brief description of the drawings]

[0009] [Figure 1] FIG. [Diagram 2] FIG. 4 is a perspective view showing a modified layer forming step. [Diagram 3] FIG. 11 is an explanatory diagram showing a dicing tape attaching step. [Figure 4] FIG. 1 is an explanatory diagram showing a conventional division step. [Diagram 5] FIG. 13 is another explanatory diagram showing a conventional division step. [Figure 6] FIG. 11 is an explanatory diagram showing a first division step that constitutes a division step. [Figure 7] FIG. 11 is an explanatory diagram showing a second division step that constitutes the division step. [Figure 8] FIG. 11 is an explanatory diagram showing a division step. [Figure 9] FIG. 11 is another explanatory diagram showing the division step. [Figure 10] FIG. 11 is yet another explanatory diagram showing the division step. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] A wafer dividing method according to the present embodiment will be described with reference to the drawings. FIG. 1 is a perspective view showing a wafer. The wafer 10 shown in FIG. 1 is a semiconductor wafer of, for example, silicon, gallium arsenide, or the like, and is formed in a substantially plate shape. A surface 11 of the wafer 10 is partitioned into a plurality of regions by lattice-shaped dividing lines 13, and devices 12 are formed in each region. The wafer 10 is not limited to a semiconductor wafer, and may be a ceramic, glass, or sapphire-based optical device wafer.

[0011] The wafer dividing method according to the present embodiment is performed on a wafer on which dividing starting points are formed along the planned dividing line. An example of forming a modified layer, which is an example of the dividing starting point, on the wafer will be described below. However, the dividing starting points formed on the wafer are not limited to the modified layer. The dividing starting points may be, for example, grooves (scribe lines) formed along the planned dividing line by a diamond scriber, a laser, or the like. The dividing starting points may also be, for example, grooves formed along the planned dividing line by half-cutting using a dicing saw.

[0012] Fig. 2 is a perspective view showing the modified layer forming step. The modified layer forming step shown in Fig. 2 is performed by a laser processing device 20. In the modified layer forming step, the wafer 10 is held on a holding table 21 of the laser processing device 20 via a protective tape 15. The holding table 21 is, for example, a chuck table that holds the wafer 10 by suction. The protective tape 15 is attached in advance to the front surface 11 of the wafer 10 to protect the device 12.

[0013] Moreover, the irradiation unit 22 of the laser processing device 20 is positioned on the planned dividing line 13 of the wafer 10 so that the focal point is located inside the wafer 10. The laser beam 23 emitted from the irradiation unit 22 is irradiated onto the wafer 10 from the back surface 14 side of the wafer 10, and a modified layer is formed by multiphoton absorption occurring at the focal point inside the wafer 10.

[0014] The irradiation unit 22 repeats movement along the planned division lines 13 by a horizontal movement mechanism (not shown) and irradiation with the laser beam 23, thereby forming modified layers along the planned division lines 13. Furthermore, the irradiation unit 22 is sequentially positioned on other planned division lines 13 parallel to the planned division lines 13 already irradiated with the laser beam 23 by a horizontal movement mechanism (not shown), and the above-mentioned process is repeated for each planned division line 13, so that modified layers are finally formed along all of the planned division lines 13.

[0015] The modified layer formed inside the wafer 10 is more fragile than other regions of the wafer 10. For this reason, the modified layer functions as a starting point for dividing the wafer 10 when a load is applied to the wafer 10 in order to divide the wafer 10.

[0016] In the wafer dividing method according to the present embodiment, the wafer is handled in a state of a work set in which the wafer and an annular frame are integrated by, for example, a dicing tape. In the following, an example of forming a work set by adhering a dicing tape, which is an example of a protective tape, will be described.

[0017] Fig. 3 is an explanatory diagram showing the dicing tape application step. The dicing tape application step shown in Fig. 3 is performed by a tape application device 30. In the dicing tape application step, first, the frame 17 is placed on the holding table 31 of the tape application device 30, and then the wafer 10 is placed inside the circular opening of the frame 17 with the front surface 11 facing the holding table 31.

[0018] Furthermore, the dicing tape 18 is placed so as to cover the opening of the frame 17 with the adhesive surface facing the wafer 10. Finally, the roller 32 rolls from end to end on the surface opposite to the adhesive surface of the dicing tape 18, thereby adhering the dicing tape 18 to the frame 17 and the back surface 14 of the wafer 10. This forms a work set 19. Note that the modified layer 16 formed inside the wafer 10 is shown in FIG. 3.

[0019] An example has been shown in which a modified layer is formed inside the wafer 10 by the laser processing apparatus 20 and then the work set 19 is formed by the tape application apparatus 30, but it is also possible to form a modified layer inside the wafer 10 by the laser processing apparatus 20 after forming the work set 19 by the tape application apparatus 30.

[0020] 4 and 5 are explanatory diagrams showing a conventional division step. In the following, the conventional division step will first be described in order to clarify the difference from the division step according to the present embodiment, which will be described later.

[0021] The conventional dividing step is performed by a breaking device 40 shown in Fig. 4. In this dividing step, first, the work set 19 is placed on the holding table 41 of the breaking device 40 with the front surface 11 of the wafer 10 to which the protective tape 15 is attached facing the holding table 41. The holding table 41 then holds the work set 19.

[0022] The holding table 41 may hold the work set 19 by, for example, clamping the frame 17 with a clamp (not shown), or the holding table 41 may hold the wafer 10 by suction via the protective tape 15. The holding table 41 may hold the work set 19 by performing both of these operations.

[0023] Thereafter, the breaking device 40 presses the wafer 10 via the dicing tape 18 with the roller 42 of the breaking device 40 to divide the wafer 10. More specifically, the breaking device 40 rolls the roller 42 from one end of the frame 17 to the other end on the surface opposite to the adhesive surface of the dicing tape 18 so as to cross the opening of the frame 17 as shown by the arrow 43 in Figs. 4 and 5, thereby applying a vertical load to the wafer 10 when the roller 42 passes over the wafer 10. As a result, a crack 161 is generated starting from the modified layer 16 due to the stress generated in the wafer 10, or a crack that was generated when the modified layer 16 was formed progresses, and the wafer 10 is broken along the planned division line 13 and divided into a plurality of chips.

[0024] 5, the rollers 42 have a length equal to or greater than the diameter of the annular frame 17. Therefore, the rollers 42 can press the entire area of ​​the wafer 10 by crossing the opening of the frame 17. However, in the conventional dividing step, even though the entire area of ​​the wafer 10 is pressed, there may be an undivided area of ​​the wafer 10 where division is not performed.

[0025] The inventors of the present application have thoroughly investigated the cause of the occurrence of undivided regions in the dividing step, and have found that air can enter between the dicing tape 18 and the wafer 10 when the roller 42 rolls on the dicing tape 18 or the protective tape 15 fixed to the opposite side of the dicing tape. Specifically, they have found that when the roller 42 moves from an area outside the wafer 10 to an area inside the wafer 10, the air around the outer edge of the wafer 10 moves toward the wafer 10 as the roller 42 moves, and enters between the wafer 10 and the dicing tape 18 from an edge portion 44 of the wafer 10 that the roller 42 straddles from the outside to the inside, as shown in FIG. 5.

[0026] The inventors of the present application concluded that the intruding air prevents the load from being transmitted from the rollers 42 to the wafer 10, which contributes to the occurrence of undivided regions, and invented a dividing method that suppresses the intrusion of air by shortening the length of the edge portion of the wafer that is straddled by the rollers from the outside to the inside.

[0027] Fig. 6 is an explanatory diagram showing a first division step constituting the division step. Fig. 7 is an explanatory diagram showing a second division step constituting the division step. Fig. 8 is an explanatory diagram showing the division step. Hereinafter, the division step in the wafer division method according to the present embodiment will be described with reference to Figs. 6 to 8.

[0028] The dividing step is performed by a breaking device 50 shown in Fig. 6 and Fig. 7. The dividing step is performed in a state where the wafer 10, on which dividing starting points are formed along the planned dividing lines and on which the dicing tape 18, which is a protective tape, is attached, is held on a holding table 51. That is, prior to the dividing step, a holding step is performed in which the wafer 10 is held on the holding table 51. The holding step performed by the breaking device 50 is the same as the holding step performed by the breaking device 40, for example.

[0029] In the dividing step, the breaking device 50 presses the wafer 10 via the dicing tape 18 with the roller 52 to divide the wafer 10 along the division lines 13 (modified layer 16). In detail, the breaking device 50 rolls the roller 52 from the inside to the outside of the wafer 10 while pressing the wafer 10 via the dicing tape 18 with the roller 52.

[0030] More specifically, as a first division step, the breaking device 50 first rolls the roller 52 from the inside to the outside of the wafer 10 in a first direction indicated by an arrow 53 while pressing the wafer 10 via the dicing tape 18 with the roller 52 as shown in Fig. 6. As a result, when the roller 52 passes over the wafer 10, a vertical load is applied to the wafer 10, and a stress generated in the wafer 10 causes a crack 161 to occur starting from the modified layer 16 or a crack that occurred during the formation of the modified layer 16 to progress, thereby dividing the wafer 10.

[0031] 7, as a second division step, the breaking device 50 rolls the roller 52 from the inside to the outside of the wafer 10 in a second direction indicated by an arrow 54 while pressing the wafer 10 with the roller 52 via the dicing tape 18. As a result, a vertical load is applied to the wafer 10 when the roller 52 passes over the wafer 10, and a stress generated in the wafer 10 causes a crack 161 to occur starting from the modified layer 16 or a crack that occurred during the formation of the modified layer 16 to progress, thereby dividing the wafer 10.

[0032] The division step of the division method according to the present embodiment described above differs from the conventional division step in at least the following two points.

[0033] The first point is that the roller 52 rolls from the inside to the outside of the wafer 10. That is, the start point of the movement of the roller 52, which is performed while pressing the wafer 10, is set inside the wafer 10, and the roller 52 is moved from the start point inside the wafer 10 toward the outside of the wafer 10. By moving the roller 52 from the start point inside the wafer 10 toward the outside of the wafer 10, as shown in FIG. 8, the length of the edge portion 55 of the wafer 10 that the roller 52 straddles from the outside to the inside can be significantly shortened compared to the length of the edge portion 44 in the conventional division step. This makes it possible to suppress the intrusion of gas between the wafer 10 and the dicing tape 18, which prevents the wafer 10 from being divided.

[0034] The second difference is that the roller 52 is rotated multiple times in different directions. In other words, the dividing step includes at least a first dividing step and a second dividing step in which the roller 52 moves in different directions. The first difference, in which the roller 52 moves from the inside to the outside, suppresses the intrusion of air, but limits the area of ​​the wafer 10 that is pressed by the roller 52. For this reason, it is difficult to cover the entire area to be pressed by only one movement of the roller 52. The second difference can compensate for the inconvenience caused by such a first difference.

[0035] In the dividing method according to the present embodiment described above, due to the above-mentioned differences in the dividing step, the regions that need to be pressed can be pressed by the rollers 52 while preventing the intrusion of gas between the wafer 10 and the dicing tape 18. This makes it possible to reduce the occurrence of undivided regions in the dividing step compared to the conventional method, thereby improving the division rate of the wafer 10. Therefore, according to the dividing method according to the present embodiment, the wafer 10 can be divided well by roller breaking.

[0036] In this embodiment, as shown in Fig. 8, the first direction and the second direction are different from each other by 180°, but the first direction and the second direction may be different from each other. By making the first direction and the second direction different, the area of ​​the wafer 10 pressed in the first division step and the area of ​​the wafer 10 pressed in the second division step are at least partially different. Therefore, a wider range can be pressed than when only one of the first division step and the second division step is performed.

[0037] If the first direction and the second direction are different by 180°, it is possible to efficiently press a wide range of the wafer 10 by two movements of the rollers 52. Therefore, if the division step is composed of a first division step and a second division step, it is desirable that the first direction and the second direction are different by 180°.

[0038] In this embodiment, as shown in FIG. 8, the area of ​​the wafer 10 pressed by the roller 52 in the first division step and the area of ​​the wafer 10 pressed by the roller 52 in the second division step partially overlap, but such a configuration is desirable because it is possible to avoid the occurrence of a gap between the pressed areas, which results in the occurrence of an area that is not pressed. By partially overlapping the areas pressed by the roller 52 moving from the inside to the outside, it is possible to prevent the formation of an undivided area near the center of the wafer 10. Furthermore, it is more desirable that the area pressed by the roller 52 in the division step includes the entire area of ​​the wafer 10. This makes it possible to prevent the formation of an undivided area in the entire area from near the center to the peripheral part of the wafer 10.

[0039] Furthermore, in the present embodiment, an example has been shown in which the rollers 52 move on the dicing tape 18 while pressing the wafer 10, but the rollers 52 may move relatively to the wafer 10. Therefore, the holding table 51 may move in the horizontal direction while the rollers 52 are stopped while pressing the wafer 10. In this case as well, a wide range of the wafer 10 can be pressed, and therefore the same effect as in the case in which the rollers 52 move can be obtained.

[0040] In addition, in the present embodiment, an example has been shown in which the front surface 11 of the wafer 10 is held by the holding table 51 and the wafer 10 is pressed from the back surface 14 side by the rollers 52, but the back surface 14 of the wafer 10 may be held by the holding table 51 and the wafer 10 may be pressed from the front surface 11 side by the rollers 52. When pressing the wafer 10 from the front surface 11 side, the wafer 10 may be pressed by the rollers 52 via the protective tape 15 provided on the front surface 11 side. This makes it possible to suppress damage to the device 12 due to pressing, etc.

[0041] In addition, although not specifically mentioned in this embodiment, it is preferable that the holding table 51 has a holding surface made of an elastic material. When the wafer 10 is held on the holding surface made of an elastic material, the wafer 10 sinks into the holding surface and is bent by the pressure of the rollers 52, so that a large stress is generated in the wafer 10. This makes it possible to efficiently break the wafer 10, and as a result, it is possible to suppress the occurrence of undivided regions. However, the holding surface of the holding table 51 is not limited to an elastic material. For example, the protective tape 15 provided between the holding surface and the wafer 10 may play the role of forming a space into which the wafer 10 sinks, and this allows sufficient stress to be generated in the wafer 10 even if the holding surface does not sink.

[0042] Fig. 9 is another explanatory diagram showing the division step. Fig. 10 is yet another explanatory diagram showing the division step. Below, a modified example of the division step will be described with reference to Figs.

[0043] The dividing step shown in Fig. 9 is performed by a braking device 60 shown in Fig. 9. The braking device 60 differs from the braking device 50 in that the dividing steps are made up of a first dividing step, a second dividing step, and a third dividing step in which the rollers 62 move in a first direction (arrow 63), a second direction (arrow 64), and a third direction (arrow 63) that are different from each other by 120°. The other points are the same as those of the braking device 50. The braking device 60 also suppresses the intrusion of gas by moving the rollers 62 from the inside to the outside of the wafer 10.

[0044] 9 shows an example in which roller 52 is moved in three directions that are different from each other by 120°, but roller 52 may be moved in four or more different directions. Furthermore, each direction does not necessarily have to differ by a constant angle, and each direction may differ by various angles, such as 180°, 120°, and 60°.

[0045] The dividing step shown in Fig. 10 is performed by a breaking device 70 having rollers 72 with a length equal to or less than the diameter of the wafer 10 instead of the rollers 62. The dividing step shown in Fig. 10 is similar to the dividing step shown in Fig. 9 in that it is composed of a first dividing step, a second dividing step, and a third dividing step in which the rollers 72 move in a first direction (arrow 73), a second direction (arrow 74), and a third direction (arrow 73), which are different by 120°. The starting point of the movement of the rollers 72 in each of the first dividing step, the second dividing step, and the third dividing step is determined to be a position where the rollers 72 do not protrude from the wafer 10.

[0046] In the breaking device 70, the rollers 72 move from the inside to the outside of the wafer 10, thereby suppressing the intrusion of gas. In particular, the rollers 72 have a length equal to or less than the diameter of the wafer 10, and are arranged so as not to protrude from the wafer 10 at the start point of the movement, thereby preventing the rollers 72 from straddling the wafer 10 from the outside to the inside. In the division step shown in Fig. 10, the region 730 pressed in the first division step, the region 740 pressed in the second division step, and the region 750 pressed in the third division step cover the entire region of the wafer 10, while suppressing the intrusion of gas, so that the wafer 10 is divided well by roller breaking.

[0047] The embodiments of the present invention are not limited to the above-mentioned embodiments and modifications, and may be modified, substituted, or altered in various ways without departing from the spirit of the technical idea of ​​the present invention. Furthermore, if the technical idea of ​​the present invention can be realized in a different way due to technological progress or other derived technology, it may be implemented using that method. Therefore, the claims cover all embodiments that may be included within the scope of the technical idea of ​​the present invention. [Industrial Applicability]

[0048] As described above, according to the wafer dividing method of the present invention, it is possible to prevent the occurrence of undivided regions in the dividing step by preventing the intrusion of gas between the wafer 10 and the protective tape. Therefore, the wafer 10 can be divided satisfactorily, and the method is useful for manufacturing chips by dividing the wafer 10. [Explanation of symbols]

[0049] 10: Wafer 11: Surface 12: Device 13: Planned division line 14: Back side 15: Protective tape 16: Modified layer 17: Frame 18: Dicing tape 19: Work Set 20: Laser processing equipment 21, 31, 41, 51: Holding table 22: Irradiation unit 23: Laser beam 30: Tape application device 32, 42, 52, 62, 72: Roller 40, 50, 60, 70: Braking device 44, 55: Edge parts 161: Crack

Claims

1. A wafer dividing method for manufacturing a plurality of chips by dividing a wafer, comprising the steps of: A holding step of holding a wafer on which a protective tape is attached and on which division starting points are formed along a planned division line, on a holding table; and a dividing step of dividing the wafer along the dividing starting point by moving the roller relatively to the wafer from the inside to the outside of the wafer while pressing the wafer with the protective tape using a roller after the holding step, the dividing step including a first dividing step and a second dividing step in which the directions in which the roller moves are different. A method for dividing a wafer, comprising the steps of:

2. The area pressed by the roller in the first division step and the area pressed by the roller in the second division step partially overlap each other.

2. The method for dividing a wafer according to claim 1, wherein the step of dividing the wafer comprises the steps of:

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