Workset and wafer extension method

Abstract

To simply and reliably prevent defects in dividing a wafer and variations in the spacing between devices caused by differences in the ease of stretching a tape in two perpendicular directions, from occurring.SOLUTION: In a workset WS, a first tape T1 and a second tape T2, which have different stretchability in two perpendicular directions, are stuck to a wafer W and a ring frame F such that the directions in which they stretch easily (MD) are perpendicular to each other. An extension method of the wafer W is characterized in that the method widens a gap between devices D through: a first fixing step of stacking the first tape T1 to a back surface of the wafer W and a bottom surface of the ring frame F; a second fixing step of overlapping the second tape T2 on the first tape T1 and sticking the overlapped tapes to the back surface of the wafer W and the bottom surface of the ring frame F or sticking the second tape T2 to the front surface of the wafer W and the top surface of the ring frame F; and an extension step of extending the first tape T1 and the second tape T2.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a work set configured by holding a wafer in a ring frame with a tape, and a wafer expanding method for expanding the wafer of the work set using a lattice-shaped division portion as a starting point. [Background technology]

[0002] For example, in the manufacturing process of semiconductor devices, the surface of a disk-shaped semiconductor wafer (hereinafter simply referred to as a "wafer") is divided into a plurality of device regions by planned division lines called streets formed in a grid pattern, and devices such as ICs and LSIs are formed in each device region. Then, the wafer on which a large number of devices are thus formed is divided along the planned division lines to manufacture a plurality of semiconductor chips.

[0003] Here, known methods for forming division portions along the intended division lines on a wafer include blade dicing, which involves cutting the wafer along the intended division lines with a cutting blade to form kerfs, plasma dicing, which involves dry etching in a vacuum to form grooves in the wafer along the intended division lines, and irradiating the wafer surface with laser light to form a modified layer inside the wafer.

[0004] Once a division portion is formed on the wafer along the intended division line by any of the above methods, an expandable tape (hereinafter simply referred to as "tape") is attached to the back surface of the wafer, and the wafer is divided starting from the lattice-shaped division portion by expanding the tape.

[0005] Incidentally, the tape to be applied to the wafer is usually a long strip-shaped tape wound in a roll that is pulled out and cut to a specified length, but this tape has the property of being more stretchable in the machine direction (hereinafter referred to as the "MD direction") in which it is pulled out from the roll than in the transverse direction (hereinafter referred to as the "TD direction") perpendicular to the MD direction.The tape is applied to the wafer with the MD and TD directions aligned with the direction of the planned dividing line of the wafer.

[0006] Therefore, if the tape is expanded concentrically with the same force when dividing the wafer, the amount of expansion of the tape will differ depending on the direction, and the wafer will not be divided at all division points, resulting in problems such as poor division and variations in the spacing between the divided devices.

[0007] Therefore, Patent Document 1 proposes a wafer division method that can solve the above problem. This method is a method that prevents the occurrence of defective division of the wafer and variation in the spacing between devices due to differences in the amount of elongation of the tape by, for example, changing the size (length) of the unprocessed area of ​​the division part formed on the outer periphery of the wafer in the MD and TD directions. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2019-125598 A Summary of the Invention [Problem to be solved by the invention]

[0009] However, the method proposed in Patent Document 1 has the problem that, for example, it is not easy to change the size (length) of the unprocessed area of ​​the division part formed on the outer periphery of the wafer between the MD direction and the TD direction, and the adjustment work is difficult. In addition, it is difficult to reliably prevent the occurrence of defects such as defective division of the wafer caused by differences in the amount of elongation of the tape.

[0010] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a work set and a wafer expansion method that can simply and reliably prevent poor wafer division and variations in the spacing between devices caused by differences in the ease of stretching the tape in two perpendicular directions. [Means for solving the problem]

[0011] In order to achieve the above-mentioned object, the present invention provides a work set consisting of a wafer having devices formed in multiple areas of its surface partitioned by grid-like planned division lines, held in a ring frame by tape, wherein the tape is composed of a first tape and a second tape which have different stretchability in two perpendicular directions, and the first tape and second tape are affixed to the wafer and the ring frame so that their stretchability directions are perpendicular to each other.

[0012] The present invention also relates to a wafer expansion method for expanding the first tape and the second tape of the work set, and dividing the wafer into multiple pieces starting from a division portion formed along the planned division line of the wafer to widen the spacing between the devices, characterized in that the spacing between the devices is widened through a first fixing step of adhering the first tape to the back surface of the wafer and the bottom surface of the ring frame, a second fixing step of overlapping the second tape on the first tape and adhering it to the back surface of the wafer and the bottom surface of the ring frame, or adhering the second tape to the front surface of the wafer and the top surface of the ring frame, and an expansion step of expanding the first tape and the second tape. Effect of the Invention

[0013] According to the present invention, a first tape and a second tape, which have different stretchability in two perpendicular directions, are attached to the wafer and the ring frame so that their stretchability directions are perpendicular to each other. This offsets the stretchability and resistance of the first tape and the second tape, making it possible to simply and reliably prevent poor division of the wafer and variations in the spacing between devices due to differences in the stretchability of the tapes. [Brief description of the drawings]

[0014] [Figure 1] 1 is a perspective view of a work set according to a first embodiment of the present invention; [Diagram 2] FIG. 2 is an exploded perspective view of a work set according to the first embodiment of the present invention. [Diagram 3] FIG. 1 is a plan view of a work set according to a first embodiment of the present invention. [Figure 4] 4(a) is a cross-sectional view taken along line AA in FIG. 3, and (b) is a cross-sectional view taken along line BB in FIG. [Diagram 5] FIG. 2 is a perspective view showing a strip tape wound in a roll. [Figure 6] FIG. 2 is an exploded perspective view showing a first fixing step of the work set according to the first embodiment of the present invention. [Figure 7] 1 is a perspective view showing a state in which a first tape is attached by a first fixing step of a work set according to a first embodiment of the present invention; FIG. [Figure 8] FIG. 2 is a plan view of a work set according to a first embodiment of the present invention to which a first tape has been attached by a first fixing step. [Figure 9] 8. (a) is a cross-sectional view taken along line CC in FIG. 8, and (b) is a cross-sectional view taken along line DD in FIG. [Figure 10] 5(a) to 5(c) are longitudinal cross-sectional views showing the process of expanding a wafer in a work set according to the first embodiment of the present invention in the order of steps. [Figure 11] FIG. 11 is a perspective view of a work set according to a second embodiment of the present invention. [Figure 12] FIG. 11 is an exploded perspective view of a work set according to a second embodiment of the present invention. [Figure 13] FIG. 11 is a plan view of a work set according to a second embodiment of the present invention. [Figure 14] 13. (a) is a cross-sectional view taken along line EE in FIG. 13, and (b) is a cross-sectional view taken along line FF in FIG. [Figure 15] FIG. 11 is a plan view of a work set showing another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0016] First Embodiment First, the configuration of a work set according to a first embodiment of the present invention will be described below with reference to FIGS.

[0017] Workset Configuration As shown in Figure 1, the work set WS of this embodiment is configured as a unit by integrating the wafer W and the ring frame F using two heat-shrinkable tapes, a first tape T1 and a second tape T2, which are attached to the back surface of the wafer W and the underside of the ring frame F and cover the circular opening of the ring-shaped ring frame F.

[0018] Here, as shown in Figs. 1 to 3, the wafer W is, for example, a thin disk-shaped member made of single crystal silicon (Si), and its surface (upper surface in Figs. 1 to 3) is partitioned into a plurality of rectangular regions by mutually orthogonal lattice-like division lines (streets) L1, L2, and devices D such as ICs and LSIs are formed in each rectangular region. The wafer W having a large number of devices D formed on its surface is supported by the ring frame F via the first tape T1 and the second tape T2 attached to its rear surface (lower surface) and the lower surface of the ring frame F, as described above. Note that, as the material of the wafer W, silicon carbide (SiC), glass, ceramics, sapphire, etc., can be used in addition to silicon (Si).

[0019] Meanwhile, in the wafer W incorporated in the work set WS, division parts (not shown) are formed in a lattice pattern along the planned division lines L1, L2, and the back surface (lower surface) is ground and thinned by a grinding device (not shown). Here, methods for forming division parts along the planned division lines L1, L2 on the wafer W include a method (blade dicing) in which the wafer W is cut along the planned division lines L1, L2 with a cutting blade to form cut grooves (kerfs), plasma dicing in which grooves are formed in the wafer W along the planned division lines L1, L2 by dry etching under vacuum, and a method in which a laser beam is irradiated onto the surface of the wafer W to form a modified layer inside the wafer W.

[0020] The first tape T1 and the second tape T2 are not particularly limited in terms of material so long as they are both stretchable and heat-shrinkable, but for example, a two-layer structure is used in which an adhesive layer is laminated on a base layer made of polyolefin, polyvinyl chloride, polypropylene, etc. The first tape T1 and the second tape T2 are circular and have an outer diameter at least larger than the diameter of the wafer W, and the ring-shaped portion T12 exposed in a ring shape between the outer periphery of the wafer W and the inner periphery of the ring frame F is a portion that is likely to become loose after the first tape T1 and the second tape T2 are expanded in the expanding step of the wafer W described below (see FIG. 10(c)).

[0021] Incidentally, the first tape T1 and the second tape T2 are obtained by pulling out a long strip-shaped tape T wound in a roll in the direction of the arrow, cutting it to a specified length, and cutting the cut piece into a circle, as shown in Fig. 5, but the first tape T1 and the second tape T2 have the property of being more stretchable in the pulling-out direction (MD) than in the width direction (TD) perpendicular to the MD. In other words, the elongation rate (elastic modulus) in the pulling-out direction (MD) is greater than the elongation rate (elastic modulus) in the width direction (TD).

[0022] In the work set WS according to this embodiment, first, the first tape T1 is attached to the back surface (lower surface) of the wafer W and the lower surface of the ring frame F, and the second tape T2 is attached to the lower surface of the first tape T1 so as to overlap the first tape T1. Here, the first tape T1 and the second tape T2 have an easily stretchable MD direction and a less stretchable TD direction that are perpendicular to each other as described above, but in this embodiment, as shown in Figs. 2 to 4, the first tape T1 and the second tape T2 are attached to the back surface (lower surface) of the wafer W and the lower surface of the ring frame F, respectively, so that the easily stretchable MD direction and the less stretchable TD direction are perpendicular to each other in the first tape T1 and the second tape T2. In this case, the first tape T1 and the second tape T2 are attached to the back surface (lower surface) of the wafer W and the lower surface of the ring frame F, respectively, so that the perpendicular MD direction and TD direction are approximately aligned with the lattice-shaped division lines L1 and L2 formed on the wafer W.

[0023] To explain the above specifically, the arrow directions in Fig. 3 are the MD direction and TD direction for the first tape T1 and the MD direction and TD direction for the second tape T2, and these MD and TD directions are perpendicular to each other in the first tape T1 and the second tape T2. The arrow directions in Fig. 4(a) are the MD direction for the first tape T1 and the TD direction for the second tape T2, and the arrow directions in Fig. 4(b) are the TD direction for the first tape T1 and the MD direction for the second tape T2, and these MD and TD directions are perpendicular to each other in the first tape T1 and the second tape T2. Therefore, the overall stretchability and resistance of the first tape T1 and the second tape T2 attached to the back surface (lower surface) of the wafer W and the lower surface of the ring frame F are the same in the two perpendicular directions.

[0024] [Wafer expansion method] Next, a method for expanding the wafer W according to the present invention will be described. The method according to the present invention includes the following steps: 1) First fixation step 2) Second fixation step 3) Expansion Step and then dividing the wafer W into a plurality of pieces starting from division parts (not shown) formed along the planned division lines L1, L2 of the wafer W, thereby widening the distance between the devices D. Each step will be described below.

[0025] 1) First fixation step: The first fixing step is a step of adhering a first tape T1 to the back surface (lower surface) of the wafer W and the lower surface of a ring frame F as shown in Fig. 6, and supporting the wafer W on the ring frame F by the first tape T1 as shown in Fig. 7. In this first step, as shown in Figs. 6 to 9, the first tape T1 is adhered to the back surface (lower surface) of the wafer W and the lower surface of the ring frame F in a state in which the orthogonal MD direction, which is easy to stretch, and the TD direction, which is difficult to stretch, are arranged substantially along the grid-like division lines L1, L2 formed on the wafer W.

[0026] That is, the arrow directions in FIG. 8 are the MD direction and TD direction of the first tape T1, the arrow direction in FIG. 9(a) is the MD direction of the first tape T1, and the arrow direction in FIG. 9(b) is the TD direction of the first tape T1.

[0027] 2) Second fixation step: The second fixing step is a step of overlapping and adhering the second tape T2 to the first tape T1 that was adhered to the back surface (lower surface) of the wafer W and the lower surface of the ring frame F in the first fixing step, and this second step constitutes the work set WS shown in Figures 1 to 4. In the work set WS thus constituted, as described above, the first tape T1 and the second tape T2 are adhered to the back surface (lower surface) of the wafer W and the lower surface of the ring frame F, respectively, such that the MD direction, which is easy to stretch, and the TD direction, which is difficult to stretch, are perpendicular to each other.

[0028] 3) Expansion Step: The expansion step is a step of radially expanding the first tape T1 and the second tape T2 in the work set WS radially outward in the radial direction of the wafer W, thereby widening the spacing between multiple devices D formed on the surface of the wafer W, and an apparatus shown in Figure 10 is used.

[0029] Here, the apparatus used in the expansion step will be described with reference to Figure 10. This apparatus has as its main components a table 10 that holds the portion (central portion) of the work set WS corresponding to the wafer W, a frame holding section 20 that holds the ring frame F of the work set WS, a lifting mechanism 30 that raises and lowers the table 10 and the frame holding section 20 relatively, and a thermal contraction means 40 that heats the ring-shaped portion T12 of the first tape T1 and the second tape T2 between the outer periphery of the wafer W and the inner periphery of the ring frame F to thermally shrink the ring-shaped portion T12.

[0030] The table 10 is a disk-shaped member, and a suction unit 11 is provided in the center of the upper surface thereof for suction-holding central portions of the first tape T1 and the second tape T2 of the work set WS. The suction unit 11 is connected to a suction source 13 via a pipe 12. An electromagnetic opening and closing valve V is provided in the pipe 12. In addition, a plurality of elongated round rod-shaped rollers 14 are rotatably disposed along the outer periphery of the table 10. Note that, when the first tape T1 and the second tape T2 are expanded as described below, these rollers 14 rotate in contact with the first tape T1 and the second tape T2, thereby fulfilling the function of reducing friction between the first tape T1 and the second tape T2 generated at the outer periphery of the table 10.

[0031] The frame holding section 20 includes a mounting plate 21 on which the lower surface of the ring frame F is placed, and a cover plate 22 that holds down the upper surface of the ring frame F. Circular holes 21a, 22a having an inner diameter larger than the outer diameter of the table 10 are respectively opened in the center of the mounting plate 21 and the cover plate 22. The mounting plate 21 and the cover plate 22 can be raised and lowered by a lifting mechanism 30 described later while holding the ring frame F of the work set WS therebetween.

[0032] The lifting mechanism 30 lifts and lowers the frame holding part 20, and is composed of a plurality of cylinder mechanisms 31 (only two are shown in FIG. 10) that support the mounting plate 21 so that it can be lifted and lowered. Here, each cylinder mechanism 31 is composed of a vertically erected cylinder 32, a piston (not shown) fitted in the cylinder 32 so as to be able to slide up and down, and a piston rod 33 that extends upward from the piston through the cylinder 32, and the mounting plate 21 is attached to the upper end of each piston rod 33. Although not shown, the interior of each cylinder 32 is divided into an upper chamber and a lower chamber by the piston.

[0033] Therefore, in each cylinder mechanism 31, if compressed air, for example, is supplied to the lower chamber of the cylinder 32 while the air in the upper chamber is exhausted, the piston rod 33 rises and the mounting plate 21 also rises, and conversely, if compressed air is supplied to the upper chamber while the air in the lower chamber is exhausted, the piston rod 33 descends and the mounting plate 21 also descends.

[0034] 10(c), the heat shrinking means 40 is disposed above the table 10, and includes a pair of heaters 42 attached to both ends of a horizontal arm 41 sandwiching the center of the wafer W, a lifting section 43 provided in the center of the arm 41, and a rotating means 44 for rotating the pair of heaters 42 about the axis of the center of the wafer W. Here, each heater 42 is composed of a far-infrared heater or the like, and can irradiate a spot with far-infrared rays having a predetermined peak waveform.

[0035] Thus, the first tape T1 and the second tape T2 are expanded by the device configured as above in the following manner.

[0036] 10(a), the work set WS is held horizontally by the frame holding part 20 and placed on the upper surface of the table 10. At this time, the opening and closing valve V is closed, so that the suction source 13 does not suck the suction part 11 of the table 10.

[0037] 10(b), when the lifting mechanism 30 is driven to lower the piston rods 33 of the cylinder mechanisms 31 from the above state, the frame holding portion 20 holding the ring frame F of the work set WS is lowered together with the piston rods 33. Then, since the ring frame F of the work set WS is positioned lower than the table 10, the first tape T1 and the second tape T2 are radially expanded by this ring frame F. At this time, since the opening / closing valve V remains closed, the suction source 13 does not suck the suction portion 11 of the table 10 (suction holding of the work set WS), and the wafer W is divided starting from the lattice-shaped division portions formed on the wafer W, and the intervals between the multiple devices D are widened.

[0038] Specifically, compared to the interval b1 between the devices D on the wafer W shown in FIG. 10(a) before the first tape T1 and the second tape T2 are expanded, the interval b2 between the devices D on the wafer W shown in FIG. 10(b) after the first tape T1 and the second tape T2 are expanded becomes larger (b2>b1). Note that when the first tape T1 and the second tape T2 are expanded, the first tape T1 and the second tape T2 are not sucked by the suction unit 11 of the table 10, so the first tape T1 and the second tape T2 are expanded smoothly. In addition, friction between the first tape T1 and the second tape T2 and the table 10 when expanding the first tape T1 and the second tape T2 is reduced by the rotation of the multiple rollers 14, so that the first tape T1 and the second tape T2 are also expanded smoothly.

[0039] As described above, when the first tape T1 and the second tape T2 are expanded and the distance between the devices D on the wafer W is increased from b1 to b2, the on-off valve V is opened and the suction source 13 draws a vacuum in the suction section 11 of the table 10, generating a negative pressure in the suction section 11, and the first tape T1 and the second tape T2 are sucked and held on the upper surface of the table 10 by this negative pressure, as shown in Fig. 10(c). Therefore, the distance between the devices D on the wafer W is maintained at the increased width b2.

[0040] Then, the work set WS is removed from the table 10 and transported to the next process. For handling at that time, the ring frame F is raised by the lifting mechanism 30 to a height position where the first tape T1 and the second tape T2 are horizontal, as shown in FIG. 10(c). At this time, the ring-shaped portion T12 of the first tape T1 and the second tape T2 expanded in the expanding process becomes loose as shown in the figure. If the ring-shaped portion T12 of the first tape T1 and the second tape T2 becomes loose in this way, as described above, the distance between the devices D of the wafer W becomes narrow when handling the work set WS. For this reason, the looseness generated in the ring-shaped portion T12 of the first tape T1 and the second tape T2 is removed by heating the ring-shaped portion T12 by the heat shrinking means 40.

[0041] That is, as shown in Fig. 10(c), the heat shrinking means 40 is positioned above the work set WS, and the arm 41 and a pair of heaters 42 attached to both ends of the arm 41 are rotated by the rotating means 44 at a predetermined speed around the center of the wafer W as an axis, while the heaters 42 irradiate far infrared rays toward the ring-shaped portions T12 of the first tape T1 and the second tape T2, respectively, to uniformly heat the ring-shaped portions T12. Then, the ring-shaped portions T12, which have heat shrinkability, shrink due to heating, and the slack that has occurred in the ring-shaped portions T12 is removed. When the slack is removed from the ring-shaped portions T12 of the first tape T1 and the second tape T2 in this way, the ring-shaped portions T12 return to a taut state without slack, so that when the work set WS is handled, the distance between the devices D of the wafer W is maintained at the expanded value b2 due to the slack in the ring-shaped portions T12.

[0042] As described above, in this embodiment, in the second fixing step, the MD direction, which is easy to stretch, and the TD direction, which is difficult to stretch, are arranged so that they are perpendicular to each other in the first tape T1 and the second tape T2. This offsets the ease of stretching and the difficulty of stretching between the first tape T1 and the second tape T2, resulting in the effect that, in the wafer W expansion step, poor division of the wafer W and variations in the spacing between devices D due to differences in the ease of stretching between the first tape T1 and the second tape T2 can be easily and reliably prevented.

[0043] <Second embodiment> Next, a second embodiment of the present invention will be described below with reference to FIGS.

[0044] In this embodiment, in a first fixing step in the method of the present invention, a first tape T1 is applied to the back surface (lower surface) of the wafer W and the lower surface of the ring frame F in the same manner as in the first embodiment, and in the next second fixing step, a second tape T2 is applied to the front surface (upper surface) of the wafer W and the upper surface of the ring frame F to form a work set WS as shown in Fig. 11. In this case, similar to the first embodiment, the first tape T1 and the second tape T2 are arranged such that their orthogonal MD and TD directions are approximately aligned with the lattice-like planned division lines L1, L2 formed on the wafer W, and are applied to the back surface (lower surface) of the wafer W and the lower surface of the ring frame F, and the front surface (upper surface) of the wafer W and the upper surface of the ring frame F, respectively.

[0045] Thus, in this embodiment, as in the first embodiment, the first tape T1 and the second tape T2 are arranged so that the MD direction, which is easy to stretch, and the TD direction, which is difficult to stretch, are perpendicular to each other. That is, the arrow directions in Figures 12 and 13 are the MD direction and TD direction for the first tape T1, and the MD direction and TD direction for the second tape T2, and these MD and TD directions are perpendicular to each other in the first tape T1 and the second tape T2. Also, the arrow direction in Figure 14(a) is the MD direction for the first tape T1 and the TD direction for the second tape T2, and the arrow direction in Figure 4(b) is the TD direction for the first tape T1 and the MD direction for the second tape T2, and these MD and TD directions are perpendicular to each other in the first tape T1 and the second tape T2. Therefore, the ease and difficulty of stretching of the first tape T1 attached to the back surface (lower surface) of the wafer W and the lower surface of the ring frame F, and the second tape T2 attached to the front surface of the wafer W and the upper surface of the ring frame F, cancel each other out in two perpendicular directions, and the overall elongation rate of these first tape T1 and second tape T2 is the same in the two perpendicular directions.

[0046] In this embodiment, the expansion step is performed using the apparatus shown in FIG. 10, as in the first embodiment. However, in the work set WS shown in FIG. 11, the first tape T1 and the second tape T2 are also arranged so that the MD direction, in which it is easy to stretch, and the TD direction, in which it is difficult to stretch, are perpendicular to each other. As a result, the ease of stretching and the difficulty of stretching are offset between the first tape T1 and the second tape T2, and in the expansion step of the wafer W, it is possible to easily and reliably prevent the occurrence of poor division of the wafer W and variations in the spacing between the devices D due to differences in the ease of stretching between the first tape T1 and the second tape T2.

[0047] In the above embodiment, the first tape T1 and the second tape T2 are arranged so that the two orthogonal directions are substantially aligned with the planned division lines L1, L2 of the wafer W, but as shown in Fig. 15, the same effect as above can be obtained even if the first tape T1 and the second tape T2 are arranged so that the two orthogonal directions are inclined with respect to the planned division lines L1, L2 of the wafer W. Fig. 15 shows a state in which the two orthogonal directions of the first tape T1 and the second tape T2 are inclined at an angle of 45° with respect to the planned division lines L1, L2 of the wafer W, but the inclination angle of both is not limited to 45° and can be arbitrary.

[0048] In addition, the present invention is not limited to the application of the embodiments described above, and various modifications are possible within the scope of the claims and the technical ideas described in the specification and drawings. [Explanation of symbols]

[0049] 10: table, 11: suction part, 12: piping, 13: suction source, 14: roller, 20: frame holding portion, 21: mounting frame, 21a: circular hole, 22: cover plate, 22a: circular hole, 30: lift mechanism, 31: cylinder mechanism, 32: cylinder, 33: piston rod, 40: heat shrink means, 41: arm, 42: heater, 43: lifting unit, 4: rotation means, b1, b2: device interval, D: device, F: frame, L1, L2: division lines, T: strip tape, T1: first tape, T2: second tape, T12: ring-shaped part of tape, V: opening and closing valve, W: wafer, WS: Workset

Claims

1. A work set configured by holding a wafer, on a ring frame by a tape, the wafer having devices formed in a plurality of regions on a surface defined by a grid-like dividing line, The work set is characterized in that the tape is composed of a first tape and a second tape which have different stretchability in two perpendicular directions, and the first tape and second tape are attached to the wafer and the ring frame so that their stretchability directions are perpendicular to each other.

2. 2. The work set according to claim 1, wherein the first tape and the second tape are overlapped and attached to the back surface of the wafer and the lower surface of the ring frame.

3. 2. The work set according to claim 1, wherein the first tape is attached to the back surface of the wafer and the lower surface of the ring frame, and the second tape is attached to the front surface of the wafer and the upper surface of the ring frame.

4. 2. The work set according to claim 1, wherein the first tape and the second tape are arranged so that two directions perpendicular to each other extend substantially along the intended division line.

5. 2. The work set according to claim 1, wherein the first tape and the second tape are arranged so that two directions perpendicular to each other are oblique to the intended division line.

6. A method for expanding a wafer, the method comprising: expanding the first tape and the second tape of the work set according to any one of claims 1 to 5; dividing the wafer into a plurality of parts starting from division parts formed along a planned division line of the wafer; and increasing a distance between the devices, the method comprising the steps of: a first fixing step of attaching the first tape to the back surface of the wafer and the lower surface of the ring frame; a second fixing step of overlapping the second tape on the first tape and attaching the second tape to the back surface of the wafer and the lower surface of the ring frame, or attaching the second tape to the front surface of the wafer and the upper surface of the ring frame; an expanding step of expanding the first tape and the second tape; and expanding the distance between the devices by a process comprising the steps of:

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