Wafer processing method and support table

Abstract

To provide a wafer processing method with which it is possible to solve trouble that a wafer is broken when a protective tape is separated.SOLUTION: Provided is a method for processing a wafer 10 that has on a surface 10a a device region 11b in which a plurality of devices 12 are formed, and an outer peripheral excess region 11a that encloses the device region 11b. This method at least includes: a protective tape disposition step in which a protective tape T1 is disposed on the surface 10a of the wafer 10; a reverse side polishing step in which a reverse side 10b of the wafer 10 is polished with the protective tape T1 side held on a chuck table 20 and a recess 14 is formed in a region that corresponds to the device region 11b, while a convex ring 15 is formed in a region that corresponds to the outer peripheral excess region 11a; and a protective tape separation step in which the protective tape is separated from the surface of the wafer 10. In the protective tape separation step, a support table 30 is used that supports the recess 14 formed on the reverse side 10b of the wafer 10.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a method for processing a wafer having a device region in which a plurality of devices are formed and an outer peripheral surplus region surrounding the device region on its surface, and a support table used for the method for processing the wafer.

Background Art

[0002] For a wafer having a device region in which a plurality of devices such as ICs and LSIs are partitioned by a dicing line and an outer peripheral surplus region surrounding the device region formed on its surface, after the back surface is ground by a grinding device to form a desired thickness, it is divided into individual device chips by a dicing device and used in electrical devices such as mobile phones and personal computers.

[0003] Also, as a method for grinding the back surface of a wafer, in order to prevent the wafer from being damaged during the conveyance of the thinned wafer and the back surface processing, the back surface region corresponding to the device region is ground to form a desired thickness, and a convex ring is formed as a reinforcing portion in the back surface region corresponding to the outer peripheral surplus region. This technology has been proposed by the applicant (see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the technology described in Patent Document 1 above, when grinding the back surface of a wafer, a protective tape is laid to protect the devices formed on the surface of the wafer. After thinning the area corresponding to the device region on the back surface of the wafer by grinding, back surface processing such as coating the back surface with a metal film is performed. Since this back surface processing involves heat processing, it becomes necessary to peel off the protective tape from the surface of the wafer. However, as described above, the area corresponding to the device region of the wafer is thinned by grinding, and even if a convex ring is formed as a reinforcing part on the back surface area corresponding to the excess outer peripheral area, the device region of the wafer is damaged when the protective tape is peeled off.

[0006] The present invention has been made in view of the above facts, and its main technical problem is to provide a wafer processing method and a support table used in the wafer processing method that can solve the problem of wafer damage when peeling off protective tape. [Means for solving the problem]

[0007] To solve the above-mentioned main technical problems, the present invention provides a wafer processing method having a device region on which a plurality of devices are formed and an outer peripheral excess region surrounding the device region, comprising at least a protective tape placement step of placing a protective tape on the surface of the wafer, a back surface grinding step of holding the protective tape side on a chuck table and grinding the back surface of the wafer to form a recess in the region corresponding to the device region and a convex ring in the region corresponding to the outer peripheral excess region, and a protective tape peeling step of peeling the protective tape from the surface of the wafer, wherein the protective tape peeling step is the relevant Recess formed on the back surface of the wafer to support Table The process involves supporting the wafer and pressing down on the surface of the wafer supported on the support table to peel off the protective tape, wherein the support table comprises a support portion sized to correspond to a recess formed on the back surface of the wafer, and a stepped portion formed on the outer circumference of the support portion corresponding to a convex ring formed on the back surface of the wafer, and a circular resin sheet having the same diameter as the support portion is disposed on the upper surface of the support portion, and when performing the protective tape peeling process, the upper surface of the resin sheet supports the recess of the wafer. A method for processing wafers is provided.

[0008] Furthermore, according to the present invention, a support table used in the wafer processing method described above comprises a support portion having a size corresponding to a recess formed on the back surface of the wafer, and a stepped portion formed on the outer circumference of the support portion corresponding to a convex ring formed on the back surface of the wafer. A circular resin sheet having the same diameter as the support portion is provided on the upper surface of the support portion. A support table is provided.

[0009] Applicable Preferably, the support portion has a suction portion that attracts and holds the recessed part of the wafer. [Effects of the Invention]

[0010] The wafer processing method of the present invention is a wafer processing method having a device region on which a plurality of devices are formed and an outer peripheral excess region surrounding the device region on its surface, comprising at least a protective tape placement step of placing a protective tape on the surface of the wafer, a back surface grinding step of holding the protective tape side on a chuck table and grinding the back surface of the wafer to form a recess in the region corresponding to the device region and a convex ring in the region corresponding to the outer peripheral excess region, and a protective tape peeling step of peeling the protective tape from the surface of the wafer, wherein the protective tape peeling step is the relevant Recess formed on the back surface of the wafer to support Table The process involves supporting the wafer and pressing down on the surface of the wafer supported on the support table to peel off the protective tape, wherein the support table comprises a support portion sized to correspond to a recess formed on the back surface of the wafer, and a stepped portion formed on the outer circumference of the support portion corresponding to a convex ring formed on the back surface of the wafer, and a circular resin sheet having the same diameter as the support portion is disposed on the upper surface of the support portion, and when performing the protective tape peeling process, the upper surface of the resin sheet supports the recess of the wafer. Therefore, when peeling the protective tape from the wafer surface, excessive force is avoided on the device area, thus eliminating the problem of wafer damage.

[0011] Furthermore, the support table of the present invention is composed of a support portion sized to correspond to a recess formed on the back surface of the wafer, and a stepped portion formed on the outer circumference of the support portion corresponding to a convex ring formed on the back surface of the wafer. A circular resin sheet having the same diameter as the support portion is placed on the upper surface of the support portion. Therefore, by using this support table when peeling protective tape from the wafer surface, excessive force is avoided on the device area, thus helping to resolve the problem of wafer damage. [Brief explanation of the drawing]

[0012] [Figure 1] This is a perspective view of the wafer and protective sheet processed according to this embodiment. [Figure 2] (a) A perspective view showing an embodiment of the backside grinding process using a grinding device, and (b) An enlarged cross-sectional view of a wafer ground by the backside grinding process. [Figure 3] This is a perspective view showing a configuration in which a wafer is held on a support table. [Figure 4] This is a perspective view showing an embodiment of the protective tape peeling process. [Figure 5] (a) A perspective view showing an embodiment of the manufacturing process for the support table, (b) A perspective view showing how resin is laid on the support portion of the support table, and (c) A perspective view showing another embodiment of the support table. [Modes for carrying out the invention]

[0013] Hereinafter, embodiments relating to a wafer processing method and a support table used in the processing method, constructed according to the present invention, will be described in detail with reference to the attached drawings.

[0014] Figure 1 shows a wafer 10, which is the workpiece in this embodiment, and a protective tape T1 that is disposed on the surface 10a of the wafer 10. The wafer 10 in this embodiment includes a semiconductor substrate made of silicon (Si) with a diameter of 100 mm and a thickness of 700 μm, and has a device region 11a on the surface 10a side of the semiconductor substrate where a plurality of devices 12 are demarcated by division lines 13, and an outer peripheral excess region 11b surrounding the device region 11a. A dashed-dot line 11 is shown on the surface 10a of the wafer 10, separating the device region 11a and the outer peripheral excess region 11b, but the dashed-dot line 11 is a virtual line added for explanatory purposes and is not actually disposed on the surface 10a of the wafer 10. Once the wafer 10 described above is prepared, a protective tape disposal process is performed to attach and integrate the protective tape T1 to the surface 10a side of the wafer 10, as shown in the upper part of Figure 1. Next, the wafer 10, which is integrated with the protective tape T1, is inverted so that the back surface 10b of the wafer 10 is exposed upwards, as shown in the lower part of Figure 1.

[0015] Next, for example, the back surface 10b is ground using a grinding device 2 (partially shown) as shown in Figure 2. This grinding device 2 includes a chuck table 20 that can hold and rotate the wafer 10, and a grinding means 21 that performs grinding on the wafer 10. The grinding means 21 includes a rotatable and vertically movable spindle 22, a grinding wheel 23 attached to the tip of the spindle 22 that rotates in conjunction with the rotation of the spindle 22, and a grinding wheel 24 fixed in an annular shape to the lower surface of the grinding wheel 23.

[0016] On the chuck table 20, the T1 side of the protective member of the wafer 10 is held, and the back surface 10b of the wafer 10 faces the grinding wheel 24. Then, the spindle 22 is rotated in the direction indicated by the arrow R1, and the grinding wheel 23 rotated together with the spindle 22 is lowered in the direction indicated by the arrow R2. At this time, the chuck table 20 is rotated in the direction indicated by the arrow R3, and the grinding wheel 24 is brought into contact with the back surface 10b of the wafer 10. The grinding wheel 24 is brought into contact with the back surface region corresponding to the device region 11b of the front surface 10a on the back surface 10b, and the other parts, that is, the regions corresponding to the outer peripheral surplus region 11a are set not to be ground. As a result, as shown in the upper part of FIG. 2(b) and FIG. 3, a concave portion 14 is formed in the central region of the back surface 10b corresponding to the ground device region 11b, and a convex ring 15 having a step with the bottom surface of the concave portion 14 is formed in the region corresponding to the outer peripheral surplus region 11a on the outer peripheral side thereof. As a result of performing the back grinding process as described above, the thickness (700 μm) of the wafer 10 before processing remains as it is in the ring 15, and the thickness of the concave portion 14 is thinned to, for example, about 30 μm. Note that the dimensions of the cross section shown in FIG. 2(b) are not described based on the actual dimensional ratio.

[0017] If the above-described back grinding process is performed, a support table 30 as shown in the lower part of FIG. 3 used when performing the protective tape peeling process described later is prepared. The support table 30 of the present embodiment includes a support portion 34 having a size corresponding to the concave portion 14 formed on the back surface 10b of the wafer 10 by the above-described back grinding process, and a step portion 32 formed on the outer periphery of the support portion 34 corresponding to the convex ring 15 formed on the back surface 10b of the wafer 10. The support portion 34 has a substantially circular shape corresponding to the concave portion 14, and the upper surface 34a of the support portion is flat. The diameter P of the support portion 34 is slightly smaller than the inner diameter of the concave portion 14, preferably formed with a dimension of about 1 to 2 mm smaller, and the height of the upper surface 34a of the support portion 34 with respect to the surface 32a of the step portion 32 is equal to the depth of the concave portion 14 or larger than the dimension of the depth, for example, 50 μm larger.

[0018] Once the above-described support table 30 is prepared, as shown in FIG. 3, the wafer 10 is inverted so that the side where the concave portion 14 is formed faces downward and the side where the protective tape T1 is adhered faces upward, and the above-described concave portion 14 is positioned and placed on the support portion 34 of the support table 30. As described above, the diameter of the support portion 34 is set smaller than the dimension of the concave portion 14, and further, since the height of the upper surface 34a of the support portion 34 with respect to the surface 32a of the step portion 32 is formed to be equal to the depth of the concave portion 14 or a dimension larger than the dimension of the depth, the support portion 34 enters the concave portion 14 of the wafer 10 and the bottom of the concave portion 14 is supported by the upper surface 34a of the support portion 34.

[0019] As described above, when the concave portion 14 of the wafer 10 is supported by the support portion 34 of the support table 30, as shown in FIG. 4, the operator holds the wafer 10 side with one hand H1 and grasps the outer peripheral end portion of the protective tape T1 with the other hand H2, and performs a protective tape peeling process of peeling the protective tape from the surface 10a of the wafer 10. Although FIG. 4 shows the procedure of peeling the protective tape T1 by the operator's hand for convenience of explanation, the protective tape peeling process of the present invention is not necessarily limited to being performed manually by the operator's hand, and may be performed by an automated machine.

[0020] Thus, the wafer processing method of the present embodiment is completed. According to the above-described embodiment, since the concave portion 14 of the wafer 10 peels the protective tape T1 from the surface 10a of the wafer 10 while pressing the device region 11b supported from below by the support portion 34 of the support table 30 from above, an excessive force is avoided from acting on the device region, and the problem of the wafer 10 being damaged is solved.

[0021] The support table 30 described above can be manufactured in the form shown in Figure 5, for example. Figure 5(a) shows a base material 30' for manufacturing the support table 30. The base material 30' is, for example, a cylindrical member made of silicon (Si). When manufacturing the support table 30 from the base material 30', the grinding device 40 shown in Figure 5(a) is used (only a part is shown). The grinding device 40 comprises a rotating spindle 42, a disc-shaped grinding wheel 43 fixed to the tip of the rotating spindle 42, and a spindle housing 44 that rotatably supports the rotating spindle 42. The rotating spindle 42 is rotationally driven by a spindle motor (not shown) disposed on the rear end side of the spindle housing 44, and the grinding device 40 is equipped with a moving means (not shown) for relatively moving the spindle housing 44 and a chuck table (not shown) that holds the base material 30'. The grinding wheel 43 is, for example, a grinding wheel in which diamond abrasive grains are fixed by nickel plating, has a diameter of 60 mm and a thickness of 10 mm, and the outer edge of the grinding wheel 43 is made up of a substantially flat surface.

[0022] When manufacturing the support table 30 from the base material 30', the base material 30' is held in the chuck table, appropriate alignment is performed, and as shown in Figure 5(a), the grinding wheel 43 is positioned on the upper surface of the region in the base material 30' where the stepped portion 32 is formed, so as to be in contact with the annular line 34b defining the support portion 34 from the outside. Next, the grinding wheel 43 is rotated in the direction indicated by arrow R4, and the base material 30' is rotated in the direction indicated by arrow R5. Once the base material 30' has been rotated, the grinding wheel 43 is lowered at a speed of, for example, 1 μm / second, to grind the outer peripheral region of the base material 30' from the upper surface until the stepped portion 32 is formed. In this way, the support table 30, which has the support portion 34 and the stepped portion 32 as described with reference to Figure 3, is formed.

[0023] The support table of the present invention is not limited to the form of the support table 30 described above. For example, as shown in Figure 5(b), a resin (e.g., a resin sheet T2) that serves as a cushioning material for protecting the wafer 10 may be laid on the upper surface of the support portion 34, which contacts the recess 14 formed on the back surface 10b side of the wafer 10 when supporting the wafer 10. The sheet T2 is, for example, a resin sheet formed with the same diameter as the support portion 34, and is preferably a heat-sealable sheet, which can be selected from, for example, a polyolefin sheet or a polyester sheet. When a polyolefin sheet is selected as the sheet T2 and laid on the support portion 34, the sheet T2 is placed on the support portion 34, heated to near its melting point, and then pressed and attached using a pressure roller or the like (not shown). By arranging the sheet T2 on the support portion 34 in this manner, when the wafer 10 is supported by the support portion 34, the sheet T2 functions as a cushioning material, and the problem of the wafer 10 being damaged when the protective tape peeling configuration described with reference to Figure 4 is carried out is more reliably avoided. Alternatively, instead of the sheet T2, a layer of liquid resin may be dropped onto the support portion 34 and solidified, which can also function as the cushioning material described above.

[0024] The support table 30 is not limited to the above-described form. As shown in Figure 5(c), a plurality of suction parts 35 for suction holding the wafer 10 may be formed on the support part 34 to which the sheet T2 is attached and on the sheet T2. Then, a suction means (not shown) is connected to the suction parts 35 via a stepped part 32 to generate a negative pressure Vm on the support part 34, positioning the recess 14 on the support part 34 and suction holding the wafer 10. As a result, when peeling the protective tape T1 from the surface 10a of the wafer 10 as described above, the wafer 10 can be reliably suction-fixed onto the support table 30, and the protective tape T1 can be peeled off stably. Note that the suction parts 35 are also effective even when the sheet T2 is not attached, and contribute to the stable holding of the wafer 10.

[0025] The protective tape peeling process described above may be carried out by providing the support table 30 independently, or it may be implemented in a peeling device configured when the protective tape peeling process described above is automated. It may also be implemented in other processing equipment. [Explanation of symbols]

[0026] 2: Grinding equipment 20: Chuck Table 22: Spindle 23: Grinding Wheel 24: Grinding wheel 10: Wafer 10a: surface 10b: Back side 11: Dot-dashed line 11a: Peripheral surplus region 11b: Device area 12: Devices 13: Planned division line 14: Recess 15: Ring 30: Support Table 30': Base material 32: Stepped section 34: Support part 35: Suction hole 40: Grinding equipment 42: Rotating spindle 43: Grinding Wheel 44: Spindle Housing T1: Protective tape T2: Seat

Claims

1. A method for processing a wafer having a device region on which multiple devices are formed and an outer peripheral surplus region surrounding the device region, A protective tape placement process in which protective tape is placed on the surface of the wafer, A back surface grinding process in which the protective tape side is held on a chuck table and the back surface of the wafer is ground to form a recess in the area corresponding to the device area and a convex ring in the area corresponding to the excess area on the outer periphery, A protective tape peeling process in which protective tape is peeled off from the surface of the wafer, It has at least the following features: The protective tape peeling step is a process of supporting a recess formed on the back surface of the wafer with a support table, and peeling off the protective tape by pressing the surface of the wafer supported by the support table, wherein the support table comprises a support portion sized to correspond to the recess formed on the back surface of the wafer, and a stepped portion formed on the outer circumference of the support portion corresponding to a convex ring formed on the back surface of the wafer, and a circular resin sheet having the same diameter as the support portion is disposed on the upper surface of the support portion, and when performing the protective tape peeling step, the upper surface of the resin sheet supports the recess of the wafer, a wafer processing method.

2. A support table for use in the wafer processing method described in claim 1, comprising a support portion having a size corresponding to a recess formed on the back surface of the wafer, and a stepped portion formed on the outer circumference of the support portion corresponding to a convex ring formed on the back surface of the wafer, wherein a circular resin sheet having the same diameter as the support portion is disposed on the upper surface of the support portion.

3. The support table according to claim 2, wherein the support portion is formed by a suction portion for suction holding a recess of a wafer.

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