Application method of protective tape

Abstract

To provide an application method of a protective tape that can prevent the generation of cutting debris from the protective tape.SOLUTION: An application method of a protective tape includes a holding step of holding the back surface 2b side of a wafer 2 on a holding table 8, a protective tape application step of placing the application surface 14a of a protective tape 14 on the front surface 2a of the wafer 2 and pressing it to apply it, and a cutting step of cutting the protective tape 14 in accordance with the outer shape of the wafer 2. In the cutting step, an annular cutter 44 having an annular cutting blade 44a having an outer shape corresponding to the outer shape of the wafer 2 is positioned at the outer shape of the wafer 2 and pressed against it to cut the protective tape 14.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a method for attaching a protective tape to the surface of a wafer.

Background Art

[0002] A wafer on which a plurality of devices such as ICs and LSIs are partitioned by a dicing line and formed on the surface is ground on the back surface by a grinding device to a predetermined thickness, and then diced into individual device chips by a dicing device. Each of the diced device chips is used in electrical devices such as mobile phones and personal computers.

[0003] When grinding the back surface of the wafer, a protective tape is attached to the surface of the wafer held on the holding table so as not to damage the surface of the wafer (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, after attaching the protective tape to the surface of the wafer, when the cutter is moved along the outer periphery of the wafer to cut the protective tape, the cutting chips of the protective tape may adhere to the surface of the protective tape. In such a case, when grinding the back surface of the wafer, the cutting chips of the protective tape are sandwiched between the holding table and the protective tape, so there is a problem that the wafer cannot be ground to a uniform thickness. In addition, when grinding the back surface of the wafer, the cutting chips of the protective tape may sometimes lift the wafer partially. In such a case, dimples corresponding to the cutting chips are formed on the back surface of the ground wafer, so there is a problem that the quality of the device deteriorates.

[0006] The above problem can occur not only in the adhesive tape with an adhesive layer laid on the adhesive surface of the protective tape, but also in a thermocompression bonding tape having no adhesive layer such as polyolefin, or a protective tape having a three-layer structure. Examples of the protective tape having a three-layer structure include those having a sheet disposed on the surface of a wafer, a gel-like resin laid on the upper surface of this sheet, and a sheet disposed so as to cover the gel-like resin.

[0007] An object of the present invention is to provide a method for attaching a protective tape that can prevent the generation of cut chips of the protective tape.

Means for Solving the Problem

[0008] According to the present invention, the following method for attaching a protective tape for solving the above problems is provided. That is, "A method for attaching a protective tape to the surface of a wafer, comprising: a holding step of holding the back surface side of the wafer on a holding table; a protective tape attaching step of disposing the attaching surface of the protective tape on the surface of the wafer and pressing it to attach; a cutting step of cutting the protective tape corresponding to the outer shape of the wafer, and including: a method for attaching a protective tape, in which in the cutting step, an annular cutter having an annular cutting blade having an outer shape corresponding to the outer shape of the wafer is positioned and pressed against the outer shape of the wafer to cut the protective tape" is provided.

[0009] Also, according to the present invention, the following method for attaching a protective tape for solving the above problems is provided. That is, "A method for attaching a protective tape to the surface of a wafer, comprising: a tape body preparation step of preparing a tape body having a protective tape and a cover sheet covering the attaching surface of the protective tape; a holding step of holding the back surface side of the wafer on a holding table; A protective tape sticking step of peeling the cover sheet from the tape body, disposing the sticking surface of the protective tape on the surface of the wafer, and pressing and sticking it; A cutting step of cutting the protective tape corresponding to the outer shape of the wafer, and In the cutting step, an annular cutter having an annular cutting edge having an outer shape corresponding to the outer shape of the wafer is positioned and pressed against the outer shape of the wafer to cut the protective tape, and a protective tape sticking method is provided.

[0010] Preferably, an adhesive layer is laid on the sticking surface of the protective tape. There may be no adhesive layer on the sticking surface of the protective tape, and the protective tape may be a thermocompression bonding tape that is pressure-bonded by heat.

[0011] In the cutting step, it is desirable to position the annular cutter from the protective tape side.

Effect of the Invention

[0012] In the protective tape sticking method of the present invention, after the sticking surface of the protective tape is stuck to the surface of the wafer, in the cutting step, an annular cutter having an annular cutting edge having an outer shape corresponding to the outer shape of the wafer is positioned and pressed against the outer shape of the wafer to cut the protective tape. Therefore, the generation of cutting scraps of the protective tape can be prevented. Therefore, according to the present invention, when grinding the back surface of the wafer, it is possible to prevent the cutting scraps of the protective tape from being sandwiched between the holding table and the protective tape, so that the problem that the wafer cannot be ground to a uniform thickness is solved. Further, according to the present invention, when grinding the back surface of the wafer, it is possible to prevent the cutting scraps of the protective tape from partially lifting the wafer, so that the problem that dimples are generated on the ground back surface of the wafer and the quality of the device is deteriorated is also solved.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0014] Hereinafter, preferred embodiments of the protective tape sticking method according to the present invention will be described with reference to the drawings.

[0015] (Wafer 2) In FIG. 1, a disk-shaped wafer 2 to which a protective tape is stuck by the protective tape sticking method of the present invention is shown. The wafer 2 can be formed from an appropriate semiconductor material such as silicon. The surface 2a of the wafer 2 is partitioned into a plurality of rectangular regions by grid-shaped division planned lines 4. Devices 6 such as ICs and LSIs are formed in each of the plurality of rectangular regions.

[0016] (Holding process) In this embodiment, first, a holding process is performed in which the back surface 2b side of the wafer 2 is held by a holding table.

[0017] The holding process can be performed using, for example, the holding table 8 shown in FIG. 1. A circular suction chuck 10 is arranged at the upper end of the holding table 8. The suction chuck 10 is formed of a porous member such as porous ceramics. Further, the suction chuck 10 is connected to a suction means (not shown).

[0018] In the holding process, first, as shown in Fig. 1(a), with the back surface 2b of the wafer 2 facing downward, the wafer 2 is placed on the upper surface of the holding table 8. Then, a suction means generates a suction force on the upper surface of the suction chuck 10. As a result, as shown in Fig. 1(b), the back surface 2b side of the wafer 2 is held by the suction chuck 10 of the holding table 8.

[0019] (Tape body preparation process) Also, a tape body preparation process is performed to prepare a tape body having a protective tape and a cover sheet covering the sticking surface of the protective tape. The tape body preparation process may be performed before or after the holding process.

[0020] The tape body prepared in the tape body preparation process may be, for example, the tape body 12 shown in Fig. 2. The tape body 12 has a strip-shaped protective tape 14 and a strip-shaped cover sheet 16 covering the sticking surface 14a of the protective tape 14. The shape of the protective tape 14 and the shape of the cover sheet 16 are substantially the same. The tape body 12 is a roll tape in which the cover sheet 16 is detachably attached to the sticking surface 14a of the protective tape 14 and wound in a cylindrical shape.

[0021] The protective tape 14 of the tape body 12 may be an adhesive tape with an adhesive layer (adhesive layer) laid on the sticking surface 14a, or a heat-pressure bonding tape that can be pressure-bonded with heat without an adhesive layer on the sticking surface 14a. The heat-pressure bonding tape is a tape made of a thermoplastic synthetic resin (for example, a polyolefin-based resin), and when heated to a temperature near the melting point, it softens or melts and exhibits adhesive force. When the protective tape 14 is an adhesive tape, a cover sheet 16 is provided on the sticking surface 14a. On the other hand, when the protective tape 14 is a heat-pressure bonding tape, the cover sheet 16 may not be provided on the sticking surface 14a.

[0022] (Protective tape sticking process) After performing the holding process and the tape body preparation process, a protective tape attaching process is performed in which the attaching surface 14a of the protective tape 14 is disposed on the surface 2a of the wafer 2 and pressed for attachment. When the tape body 12 has the cover sheet 16, the cover sheet 16 is peeled off from the tape body 12 in the protective tape attaching process.

[0023] (Protective Tape Attaching Device 18) The protective tape attaching process can be performed, for example, using the protective tape attaching device 18 shown in FIG. 2. The protective tape attaching device 18 includes a feeding means 20 for feeding out the protective tape 14 from the tape body 12, a winding means 22 for winding up the used protective tape 14, and a pressing means 24 disposed between the feeding means 20 and the winding means 22 and rolling while pressing the protective tape 14 onto the wafer 2 for attachment.

[0024] (Feeding Means 20) The feeding means 20 includes a support roller 26 for supporting the tape body 12 wound in a cylindrical shape, a feeding roller 28 for feeding out the protective tape 14 from the tape body 12 supported by the support roller 26, a motor (not shown) for rotating the feeding roller 28, and a driven roller 30 that rotates as the feeding roller 28 rotates. The feeding means 20 is configured to feed out the protective tape 14 sandwiched between the feeding roller 28 and the driven roller 30 from the tape body 12 by rotating the driven roller 30 together with the feeding roller 28 by the motor. Further, the cover sheet 16 is peeled off from the protective tape 14 that has passed between the feeding roller 28 and the driven roller 30, and the peeled cover sheet 16 is wound up and recovered by the recovery roller 32. When the tape body 12 does not have the cover sheet 16, the recovery roller 32 is unnecessary.

[0025] (Winding Means 22) The take-up means 22 includes a take-up roller 34 for taking up the used protective tape 14, a motor (not shown) for rotating the take-up roller 34, and a guide roller 36 for guiding the used protective tape 14 to the take-up roller 34. The take-up means 22 is configured to wind up the used protective tape 14 having a circular opening 14b (see FIG. 6) formed therein that hits the portion adhered to the wafer 2, while guiding it with the guide roller 36, by rotating the take-up roller 34 with the motor.

[0026] (Pressing means 24) The pressing means 24 includes a pressing roller 37 that is vertically movable in the Z-axis direction (vertical direction) indicated by an arrow Z in FIG. 2 and is rollable in the X-axis direction (a direction orthogonal to the Z-axis direction) indicated by an arrow X, a lifting means (not shown) for lifting and lowering the pressing roller 37 in the Z-axis direction, and a rolling means (not shown) for rolling the pressing roller 37 in the X-axis direction. When the protective tape 14 is a thermocompression bonding tape, heating means for heating the outer peripheral surface of the pressing roller 37 to a temperature at which the protective tape 14 softens or melts is provided. The lifting means positions the pressing roller 37 at the upper standby position shown in FIG. 2 and the lower pressing position shown in FIG. 3(a). The rolling means rolls the pressing roller 37 positioned at the lower pressing position in the X-axis direction. In FIG. 2, the direction perpendicular to the plane of the paper and orthogonal to the X-axis direction and the Z-axis direction is defined as the Y-axis direction. The plane defined by the X-axis direction and the Y-axis direction is substantially horizontal.

[0027] In the protective tape attaching step, first, the tape body 12 is set on the protective tape attaching device 18. At this time, as shown in FIG. 2, first, the tape body 12 is supported by the support roller 26 of the protective tape attaching device 18. Next, the protective tape 14 is pulled out from the tape body 12, and the pulled-out protective tape 14 is passed between the feed roller 28 and the driven roller 30. Next, after passing the protective tape 14 under the guide roller 36, the tip of the protective tape 14 is wound around the take-up roller 34. Then, the pulled-out protective tape 14 is adjusted to a state of being stretched without slack. Also, the protective tape 14 between the feed roller 28 and the guide roller 36 is arranged so that the adhering surface 14a faces downward. When the tape body 12 has the cover sheet 16, the tip of the cover sheet 16 is wound around the recovery roller 32.

[0028] After setting the tape body 12 on the protective tape attaching device 18, the adhering surface 14a of the protective tape 14 is disposed on and pressed against the surface 2a of the wafer 2 for attachment. At this time, first, the holding table 8 holding the wafer 2 is positioned below the protective tape 14 between the feed roller 28 and the guide roller 36. Next, the pressing roller 37 is lowered from the upper standby position to the lower pressing position by the elevating means. Next, as shown in FIGS. 3(a) and 3(b), the pressing roller 37 is rolled in the X-axis direction by the rolling means, and the adhering surface 14a of the protective tape 14 is pressed against the surface 2a of the wafer 2. Thereby, the adhering surface 14a of the protective tape 14 can be attached to the surface 2a of the wafer 2.

[0029] When attaching the protective tape 14 to the wafer 2, when the protective tape 14 is a thermocompression bonding tape, the pressing roller 37 is preheated by the heating means to the temperature at which the protective tape 14 softens or melts. However, when the protective tape 14 is an adhesive tape, heating of the pressing roller 37 is unnecessary.

[0030] (Cutting step) After performing the protective tape attaching step, a cutting step of cutting the protective tape 14 corresponding to the outer shape of the wafer 2 is performed.

[0031] The cutting process can be carried out using, for example, the cutting device 38 shown in Fig. 4(a). The cutting device 38 includes a spindle 40 extending in the vertical direction, a disk-shaped cutter mount 42 fixed to the lower end of the spindle 40, an annular cutter 44 mounted on the lower surface of the cutter mount 42, and imaging means (not shown). Although not shown, the spindle 40 is moved up and down in the Z-axis direction by lifting means, and its position in the XY plane is adjusted by positioning means. An air injection port 42a for injecting air for cleaning the protective tape 14 is provided at the central portion of the lower surface of the cutter mount 42. The air injection port 42a is connected to an air supply source (not shown). A cutting edge 44a is provided at the lower end of the annular cutter 44, and the outer shape of the cutting edge 44a corresponds to the outer shape of the wafer 2. Regarding the shape of the cutting edge of the annular cutter 44, as shown in Fig. 4(a), the lower end position of the cutting edge 44a may be constant over the entire circumference, or, as shown in Fig. 4(b), it may be a saw-tooth-shaped jagged cutting edge 44a' (a cutting edge 44a' in which a large number of triangles with one vertex positioned at the lower end are arranged over the entire circumference).

[0032] In the cutting process, first, the position of the cutting edge 44a of the annular cutter 44 is positioned to the outer shape of the wafer 2. At this time, the wafer 2 is imaged from above by the imaging means of the cutting device 38, and the positions of any three points on the outer circumference of the imaged wafer 2 are obtained. Next, the center position of the wafer 2 is detected from the obtained positions of the three points. Then, the position of the annular cutter 44 is adjusted by the positioning means of the cutting device 38 so that the detected center position of the wafer 2 coincides with the center position of the annular cutter 44.

[0033] Once the position of the cutting edge 44a of the annular cutter 44 is positioned on the outer shape of the wafer 2, the protective tape 14 is cut. At this time, as shown in FIG. 5, the annular cutter 44 is lowered by the elevating means of the cutting device 38, and the cutting edge 44a of the annular cutter 44 is pressed against the protective tape 14. As a result, the protective tape 14 can be cut circularly along the outer shape of the wafer 2. After cutting the protective tape 14, the annular cutter 44 is raised, and then the used protective tape 14 (the protective tape 14 with the circular opening 14b formed) shown in FIG. 6 is wound up by the winding roller 34. Further, after cutting the protective tape 14, it is preferable to jet air from the air jet port 42a of the cutter mount 42 to clean the upper surface of the protective tape 14.

[0034] In this way, in the cutting process, since the annular cutter 44 having the annular cutting edge 44a having an outer shape corresponding to the outer shape of the wafer 2 is positioned and pressed against the outer shape of the wafer 2 to cut the protective tape 14, generation of cutting chips of the protective tape 14 can be prevented. On the other hand, different from this embodiment, when the cutter is moved along the outer circumference of the wafer 2, cutting chips of the protective tape 14 are generated. However, in this embodiment, since the protective tape 14 is cut by the lowering operation of the annular cutter 44 and the annular cutter 44 is not moved (rotated) in the circumferential direction along the outer circumference of the wafer 2, generation of cutting chips of the protective tape 14 can be prevented.

[0035] In the cutting process of this embodiment, the annular cutter 44 is positioned from the protective tape 14 side to cut the protective tape 14, but the protective tape 14 may be cut by positioning the annular cutter 44 from the wafer 2 side. However, when the annular cutter 44 is positioned from the wafer 2 side when the protective tape 14 is an adhesive tape, the glue of the adhesive tape may adhere to the cutting edge 44a of the annular cutter 44. Therefore, it is preferable that the protective tape 14 is a thermocompression bonding tape when the protective tape 14 is cut by positioning the annular cutter 44 from the wafer 2 side.

[0036] (Grinding process) After performing the cutting process, a grinding process is carried out to grind the back surface 2b of the wafer 2 to thin the wafer 2 to a desired thickness.

[0037] (Grinding device 46) The grinding process can be carried out, for example, using the grinding device 46 shown in FIG. 7. The grinding device 46 includes a holding table 48 that sucks and holds the wafer 2, and a grinding means 50 that grinds the wafer 2 sucked and held by the holding table 48. The grinding means 50 includes a spindle 52 that extends in the vertical direction, and a disk-shaped wheel mount 54 fixed to the lower end of the spindle 52. An annular grinding wheel 58 is fastened to the lower surface of the wheel mount 54 by bolts 56. A plurality of grinding wheels 60 are fixed to the outer peripheral edge of the lower surface of the grinding wheel 58 and are arranged annularly at intervals in the circumferential direction.

[0038] In the grinding process, first, the back surface 2b of the wafer 2 is turned upward (the protective tape 14 is turned downward), and the wafer 2 is sucked and held on the upper surface of the holding table 48. As described above, in this embodiment, since there is no cutting debris of the protective tape 14, when the wafer 2 is sucked and held by the holding table 48, there is no cutting debris of the protective tape 14 sandwiched between the upper surface of the holding table 48 and the lower surface of the protective tape 14, and the wafer 2 is not partially lifted by the cutting debris of the protective tape 14.

[0039] After the wafer 2 is held by the holding table 48, the holding table 48 is rotated in the direction indicated by the arrow R1 in FIG. 7 at a predetermined rotational speed (for example, 300 rpm). Also, the spindle 52 is rotated in the direction indicated by the arrow R2 in FIG. 7 at a predetermined rotational speed (for example, 6000 rpm). Then, the spindle 52 is lowered to bring the grinding wheel 60 into contact with the back surface 2b of the wafer 2, and grinding water is supplied to the portion where the grinding wheel 60 contacts the back surface 2b. Thereafter, the spindle 52 is lowered at a predetermined grinding feed rate (for example, 1.0 μm / s). Thereby, the back surface 2b of the wafer 2 can be ground to thin the wafer 2 to a desired thickness.

[0040] As described above, in the present embodiment, since the protective tape 14 is cut by the downward movement of the annular cutter 44 and the annular cutter 44 is not rotated along the outer periphery of the wafer 2, generation of cutting chips of the protective tape 14 can be prevented. Therefore, according to the present embodiment, during the grinding process, cutting chips of the protective tape 14 are prevented from being caught between the holding table 48 and the protective tape 14, so that the problem that the wafer 2 cannot be ground to a uniform thickness is solved. Further, according to the present embodiment, since cutting chips of the protective tape 14 are prevented from partially lifting the wafer 2 during the grinding process, the problem that dimples are formed on the back surface 2b of the ground wafer 2 and the quality of the device 6 deteriorates is also solved.

Explanation of Signs

[0041] 2: Wafer 2a: Front surface of wafer 2b: Back surface of wafer 8: Holding table 12: Tape body 14: Protective tape 14a: Adhesive surface 16: Cover sheet 44: Annular cutter 44a: Cutting edge

Claims

1. A method for attaching a protective tape to the surface of a wafer, comprising: a holding step of holding the back side of the wafer on a holding table; a protective tape attaching step of disposing the attaching surface of the protective tape on the surface of the wafer and pressing to attach it; a cutting step of cutting the protective tape corresponding to the outer shape of the wafer, wherein in the cutting step, a ring cutter having an annular cutting blade with an outer shape corresponding to the outer shape of the wafer is positioned and pressed against the outer shape of the wafer to cut the protective tape.

2. A method for attaching a protective tape to the surface of a wafer, comprising: a tape body preparation step of preparing a tape body having a protective tape and a cover sheet covering the attaching surface of the protective tape; a holding step of holding the back side of the wafer on a holding table; a protective tape attaching step of peeling the cover sheet from the tape body, disposing the attaching surface of the protective tape on the surface of the wafer, and pressing to attach it; a cutting step of cutting the protective tape corresponding to the outer shape of the wafer, wherein in the cutting step, a ring cutter having an annular cutting blade with an outer shape corresponding to the outer shape of the wafer is positioned and pressed against the outer shape of the wafer to cut the protective tape.

3. The method for attaching a protective tape according to claim 1 or 2, wherein an adhesive layer is provided on the attaching surface of the protective tape.

4. The method for attaching a protective tape according to claim 1 or 2, wherein there is no adhesive layer on the attaching surface of the protective tape, and the protective tape is a thermocompression bonding tape that is pressure-bonded by heat.

5. The method for attaching a protective tape according to claim 1 or 2, wherein in the cutting step, the ring cutter is positioned from the protective tape side.

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