Wafer processing method and support tray

Abstract

To solve a problem of damaging a wafer when the wafer is transported, the wafer having a ground rear surface in a device region and a convex ring-shaped reinforcing portion formed in an outer peripheral excess region.SOLUTION: A wafer processing method includes at least a protective tape disposing step of disposing a protective tape T1 on a front surface 10a of a wafer 10, a back surface grinding step of holding the protective tape side on a chuck table and grinding a back surface 10b of the wafer to form a recess portion 14 in an area corresponding to a device region 11b and forming a convex ring-shaped reinforcing portion 15 in an area corresponding to an outer peripheral excess region 11a, and a wafer transport step, and includes a support tray preparation step of preparing a support tray 30 configured by a support portion 34 having a size corresponding to the recess portion formed on the back surface of the wafer and a step portion 32 which is formed on the outer periphery of the support portion 34 so as to correspond to the ring-shaped reinforcing portion 15, and a loading step of loading the back surface 1 of the wafer on the support tray.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for processing a wafer having, on its surface, a device region in which a plurality of devices are formed and a peripheral excess region surrounding the device region, and a support tray for supporting the wafer. [Background technology]

[0002] A wafer having a device area on its front surface, where a plurality of devices such as ICs and LSIs are partitioned by planned division lines, and an outer peripheral surplus area surrounding the device area, is ground on its back surface by a grinding device to form the wafer into the desired thickness, and then separated by a dicing device into individual device chips for use in electrical equipment such as mobile phones and personal computers.

[0003] In addition, as a method of grinding the back surface of a wafer, the applicant has proposed a technology in which the back surface area corresponding to the device region is ground to a desired thickness and a convex ring-shaped reinforcement portion is formed in the back surface area corresponding to the peripheral excess region so as to prevent the wafer from being damaged during back surface processing of the thinned wafer (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-019461 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, even if the above-mentioned convex ring-shaped reinforcement portion is formed on the wafer, there is a problem that, due to the thin device region (30 to 50 μm), a load is applied to the device region when the wafer is transported to the next process, such as coating the back surface of the wafer with a metal film, and there is a risk of the wafer being damaged.

[0006] In addition, when the protective tape laid when grinding the back surface of the wafer is subjected to back surface processing such as coating the back surface with a metal film, the protective tape needs to be peeled off from the front surface of the wafer because the back surface processing includes a thermal process. However, as described above, the area corresponding to the device area of ​​the wafer is thinned by grinding, and even if the above-mentioned ring-shaped reinforcing part is formed in the back surface area corresponding to the peripheral excess area, a problem occurs in that the device area of ​​the wafer is damaged when the protective tape is peeled off.

[0007] The present invention has been made in consideration of the above-mentioned facts, and its main technical object is to provide a wafer processing method and a support tray for supporting the wafer, which can solve the problem that a load is applied to the device region and the wafer is damaged when the wafer, which has been ground to a desired thickness and has a convex ring-shaped reinforcement portion formed in the back region corresponding to the peripheral excess region, is transported to the next process, and also solves the problem that there is a risk of the wafer being damaged when the protective tape is peeled off from the front surface of the wafer. [Means for solving the problem]

[0008] In order to solve the above-mentioned main technical problem, according to the present invention, there is provided a method for processing a wafer having, on its surface, a device region in which a plurality of devices are formed and a peripheral surplus region surrounding the device region, the method comprising at least a protective tape applying step of applying a protective tape to the surface of the wafer, a backside grinding step of holding the protective tape side on a chuck table and grinding the backside of the wafer to form a recess in a region corresponding to the device region and to form a convex ring-shaped reinforcement portion in a region corresponding to the peripheral surplus region, and a transporting step of transporting the wafer, and the method further comprising, before the transporting step, a support tray preparing step of preparing a support tray composed of a support portion having a size corresponding to the recess formed on the backside of the wafer and a step portion formed on the outer periphery of the support portion corresponding to the convex ring-shaped reinforcement portion formed on the backside of the wafer, and a loading step of loading the backside of the wafer on the support tray.

[0009] The method may include a protective tape peeling step of supporting the back surface of the wafer on the support tray used in the transporting step and peeling off the protective tape from the front surface of the wafer.

[0010] Furthermore, according to the present invention, there is provided a support tray for use in the above-mentioned wafer processing method, which comprises a support portion having a size corresponding to the recess formed on the back surface of the wafer, and a step portion formed on the outer periphery of the support portion corresponding to the convex ring-shaped reinforcement portion formed on the back surface of the wafer.

[0011] It is preferable that a resin is laid on the upper surface of the supporting part. Furthermore, the supporting part may be formed with a suction part for suction-holding the recessed part of the wafer, and configured to be able to suck the wafer in the protective tape peeling step. Effect of the Invention

[0012] The wafer processing method of the present invention comprises at least a protective tape applying step of applying a protective tape to the front 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 a region corresponding to the device region and a convex ring-shaped reinforcement portion in a region corresponding to the outer peripheral surplus region, and a transporting step of transporting the wafer, and before the transporting step, a support tray preparing step of preparing a support tray composed of a support portion of a size corresponding to the recess formed on the back surface of the wafer and a step portion formed on the outer periphery of the support portion corresponding to the convex ring-shaped reinforcement portion formed on the back surface of the wafer, and a loading step of placing the back surface of the wafer on the support tray, thereby eliminating the problem that a load is applied to the device region of the wafer thinned in the back surface grinding step during transport, causing damage to the wafer when transported to the next step.

[0013] Furthermore, since the support tray of the present invention is composed of a support portion of a size corresponding to the recess formed on the back surface of the wafer, and a step portion formed on the outer periphery of the support portion corresponding to the convex ring-shaped reinforcement portion formed on the back surface of the wafer, the problem of load being applied to the device region of the wafer when supporting and transporting the wafer that has been subjected to the above-mentioned back surface grinding process, and the wafer being damaged when transported to the next process, is eliminated. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 is a perspective view showing an embodiment of a protective tape disposing step according to the present embodiment. [Diagram 2] FIG. 2A is a perspective view showing an embodiment of a back grinding step performed by a grinding device, and FIG. 2B is an enlarged cross-sectional view of a wafer ground in the back grinding step. [Diagram 3] FIG. 2 is a perspective view showing a manner in which a wafer is held on a support table. [Figure 4] FIG. 11 is a perspective view showing an embodiment of a protective tape peeling step. [Diagram 5] FIG. 11 is a perspective view showing an embodiment of a conveying step. [Figure 6] FIG. 1A is a perspective view showing an embodiment of a process for manufacturing a support table; FIG. 1B is a perspective view showing an aspect of laying resin on a support portion of the support table; and FIG. 1C is a perspective view showing another embodiment of the support table. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a wafer processing method and a support tray for supporting the wafer according to the present invention will be described in detail with reference to the accompanying drawings.

[0016] (Protective tape application process) FIG. 1 shows a wafer 10, which is a workpiece in this embodiment, and a protective tape T1 disposed on a surface 10a of the wafer 10. The wafer 10 in this embodiment includes a semiconductor substrate made of silicon (Si) having a diameter of 200 mm and a thickness of 700 μm, and includes a device region 11a in which a plurality of devices 12 are partitioned by a division line 13 on the surface 10a side of the semiconductor substrate, and a peripheral excess region 11b surrounding the device region 11a. The protective tape T1 is cut out from a sheet made of polyolefin, for example, and has an adhesive layer formed on its surface. Note that, on the surface 10a of the wafer 10 shown in the figure, a dashed line 11 is shown dividing the device region 11a and the peripheral excess region 11b, but the dashed line 11 is a virtual line added for convenience of explanation, and is not actually disposed on the surface 10a of the wafer 10.

[0017] Once the wafer 10 and protective tape T1 are prepared, the protective tape T1 is attached to and integrated with the front surface 10a of the wafer 10, as shown in the upper part of Fig. 1. This completes the protective tape application process.

[0018] (Back grinding process) 2 (only a part of it is shown), a backside grinding step is performed to grind the backside 10b of the wafer 10. The grinding device 2 includes a chuck table 20 capable of rotating while holding the wafer 10, and a grinding means 21 that performs a grinding process 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 and rotating with the rotation of the spindle 22, and a grinding stone 24 fixed to the lower surface of the grinding wheel 23 in an annular shape.

[0019] The wafer 10, which is integrated by attaching the protective tape T1 to the front surface 10a in the protective tape disposing step, is transported to the grinding device 2 described above, and the protective tape T1 side of the wafer 10 is placed on the chuck table 20 and held by suction. As a result, 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 set to come into contact with the back surface region of the back surface 10b corresponding to the device region 11b of the front surface 10a, and not to grind the other portion, i.e., the region corresponding to the outer peripheral excess region 11a. As a result, as shown in Figures 2(a), (b) and the upper part of Figure 3, a recess 14 is formed in the central region of the back surface 10b corresponding to the ground device region 11b, and a convex ring-shaped reinforcing part 15 having a step between the bottom surface of the recess 14 and the region corresponding to the peripheral excess region 11a is formed. As a result of performing the back surface grinding process as described above, the thickness (700 μm) of the wafer 10 before processing remains in the ring-shaped reinforcing part 15, and the thickness of the recess 14 is thinned to, for example, about 30 μm. Note that the dimensions of the cross-sectional view shown in Figure 2(b) are not shown based on the actual dimensional ratio.

[0020] (Support tray preparation process) After or before the above back grinding step, a support tray preparation step is performed to prepare a support tray 30 as shown in the lower part of Fig. 3, which is used when performing a transport step described later. The support tray 30 of this embodiment is composed of a support part 34 formed in a shape corresponding to the recess 14 formed on the back surface 10b of the wafer 10 by the above back grinding step, and a step part 32 formed on the outer periphery of the support part 34 in correspondence with the convex ring-shaped reinforcing part 15 formed on the back surface 10b of the wafer 10. The support part 34 has a substantially circular shape corresponding to the recess 14, and an upper surface 34a of the support part 34 is flat. The diameter P of the support portion 34 is slightly smaller than the inner diameter of the recess 14 formed on the back surface 10b of the wafer 10, and is preferably formed to be approximately 1 to 2 mm smaller. The height of the upper surface 34a of the support portion 34 relative to the surface 32a of the step portion 32 is equal to the depth of the recess 14 or is slightly larger than the depth, for example, approximately 50 μm larger than the depth of the recess 14.

[0021] (Placement process) After the support tray 30 is prepared, a placing step is performed in which the back surface 10b of the wafer 10 that has been subjected to the back grinding step is placed on the support tray 30. More specifically, as shown in FIG. 3, the wafer 10 is inverted, and the side on which the recess 14 is formed faces downward and the side on which the protective tape T1 is attached faces upward, and the recess 14 is positioned and placed on the support portion 34 of the support tray 30. As described above, the diameter of the support portion 34 is set smaller than the dimension of the recess 14, and further, the height of the upper surface 34a of the support portion 34 relative to the surface 32a of the step portion 32 is formed to be equal to or slightly larger than the depth of the recess 14. Therefore, the support portion 34 enters the recess 14 of the wafer 10, and the bottom of the recess 14 is supported by the upper surface 34a of the support portion 34.

[0022] (Protective tape peeling process) As described above, if the recess 14 of the wafer 10 is supported by the support portion 34 of the support tray 30, as shown in FIG. 4, the protective tape peeling step can be performed in which the operator holds the wafer 10 with one hand H1 and grasps the outer peripheral end of the protective tape T1 with the other hand H2 to peel it off from the front surface 10a of the wafer 10. Note that, for convenience of explanation, FIG. 4 shows the procedure of peeling off the protective tape T1 by the operator's hand, but the protective tape peeling step of the present invention is not necessarily limited to being performed by the operator's manual operation, and may be performed by an automated procedure using a peeling device (not shown). According to such a protective tape peeling step, the protective tape T1 is peeled off while the recess 14 of the wafer 10 is supported from below by the support portion 34 of the support tray 30, so that excessive force is avoided from acting on the device region 11b, and the problem of the wafer 10 being damaged is solved. In addition, the protective tape peeling step is not limited to being performed before the transport step described below, and can be performed at a necessary timing after the transport step.

[0023] (Transportation process) After the protective tape peeling step is performed after the placing step described above (or after the placing step but before the protective tape peeling step is performed), the wafer 10 is supported by the support tray 30 as shown in Fig. 5 and transported to the next step (for example, a metal film coating device that performs a process of coating the back surface 10b of the wafer 10 with a metal film). The transporting step includes transporting the support tray 30 to the next step by directly holding it by an operator, transporting the support tray 30 to the next step using a transport means that supports the support tray 30 from below, storing multiple support trays 30 supporting the wafers 10 as described above in a storage case such as a cassette, and transporting them all together to the next step. With the above, the wafer processing method of this embodiment is completed.

[0024] According to the above-described embodiment, the transport process is carried out using the support tray 30 that supports the recess 14 formed in the back surface 10b of the wafer 10. This eliminates the problem that a load is applied to the device region 11b of the wafer 10 that has been thinned in the back surface grinding process during transport, causing damage to the wafer 10 when transported to the next process.

[0025] The support tray 30 described above can be manufactured in a form as shown in FIG. 6, for example. FIG. 6(a) shows a base material 30' for manufacturing the support tray 30. The base material 30' is, for example, a cylindrical member made of silicon (Si). When manufacturing the support tray 30 described above from the base material 30', a grinding device 40 shown in FIG. 6(a) is used (only a part of it is shown). The grinding device 40 includes a rotating spindle 42, a disk-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 driven to rotate by a spindle motor (not shown) disposed on the rear end side of the spindle housing 44. The grinding device 40 includes a chuck table (not shown) that holds the spindle housing 44 and the base material 30', and a moving means (not shown) that moves the chuck table. The grinding wheel 43 is, for example, a grinding wheel in which diamond abrasive grains are fixed with nickel plating, and has a diameter of 60 mm and a thickness of 10 mm. The outer peripheral edge of the grinding wheel 43 is formed as a substantially flat surface.

[0026] When the support tray 30 is manufactured from the base material 30', the base material 30' is held on the chuck table, and appropriate alignment is performed. As shown in FIG. 6(a), the grinding wheel 43 is positioned so as to be in contact with the annular line 34b defining the support portion 34 from the outside on the upper surface of the region in which the step portion 32 is formed in the base material 30'. Next, the grinding wheel 43 is rotated in the direction indicated by the arrow R4, and the base material 30' is rotated in the direction indicated by the arrow R5. After the base material 30' is rotated, the grinding wheel 43 is lowered at a speed of, for example, 1 μm / sec to grind the outer peripheral region of the base material 30' from the upper surface to a position where the step portion 32 is formed. In this manner, the support tray 30 having the support portion 34 and the step portion 32 described based on FIG. 3 is formed.

[0027] The support tray of the present invention is not limited to the form of the support tray 30 described above. For example, as shown in FIG. 6(b), a resin (e.g., a resin sheet T2) serving as a buffer material for protecting the wafer 10 may be laid on the upper surface 34a of the support part 34 with which the recess 14 formed on the back surface 10b of the wafer 10 abuts when supporting the wafer 10. The sheet T2 is, for example, a resin sheet formed with the same diameter as the support part 34, and is preferably a thermocompression sheet. The thermocompression sheet is, for example, selected from a polyolefin sheet or a polyester sheet. When a polyolefin sheet is selected as the sheet T2 and laid on the support part 34, the sheet T2 is placed on the support part 34, heated to a temperature close to the melting point, and pressed and attached using a pressing roller or the like (not shown). By disposing the sheet T2 on the supporting portion 34 in this manner, when the wafer 10 is supported by the supporting portion 34, the sheet T2 functions as a buffer material, and the problem of the wafer 10 being damaged during the protective tape peeling step described with reference to Fig. 4 and the transport step described with reference to Fig. 5 is more reliably avoided. Note that the resin sheet serving as the buffer material is not limited to the above-mentioned sheet T2, and may be a layer formed by dropping liquid resin onto the supporting portion 34 and solidifying it, and even in this case, it can function as the above-mentioned buffer material.

[0028] The support tray 30 is not limited to the above-mentioned form. As shown in FIG. 6(c), a plurality of suction parts 35 for suction-holding the recesses 14 of the wafer 10 may be formed on the support part 34 to which the sheet T2 is attached and the sheet T2. Then, a suction means (not shown) is connected to the suction parts 35 via the support tray 30, and a negative pressure Vm is generated in the support part 34, so that the recesses 14 are positioned on the support part 34 to suction-hold the wafer 10. This allows the wafer 10 to be reliably fixed on the support tray 30 when the protective tape T1 is peeled off from the surface 10a of the wafer 10, and the protective tape T1 can be peeled off stably. The suction parts 35 are effective even when the sheet T2 is not attached, and contribute to stably holding the wafer 10. [Explanation of symbols]

[0029] 2: Grinding device 20: Chuck table 22: Spindle 23: Grinding wheel 24: Grinding wheel 10: Wafer 10a: surface 10b: Back side 11: Dot-dashed line 11a: Surplus outer area 11b: Device area 12: Device 13: Planned division line 14: Recess 15: Ring-shaped reinforcement section 30: Support tray 30': Base material 32: Step 34: Support part 34:Top surface 35: Suction hole 40: Grinding equipment 42: Rotating spindle 43: Grinding wheel 44: Spindle housing T1: Protective tape T2: Sheet

Claims

1. A method for processing a wafer having, on a surface thereof, a device region in which a plurality of devices are formed and a peripheral excess region surrounding the device region, comprising the steps of: a protective tape applying step of applying a protective tape to a front surface of the wafer; a backside grinding step of holding the protective tape side on a chuck table and grinding the backside of the wafer to form a recess in an area corresponding to the device area and a convex ring-shaped reinforcing part in an area corresponding to the outer peripheral excess area; a transport step of transporting the wafer; At least Prior to the transport step, a support tray preparation step of preparing a support tray including a support portion having a size corresponding to a recessed portion formed on the rear surface of the wafer and a step portion formed on an outer periphery of the support portion in correspondence with a protruding ring-shaped reinforcing portion formed on the rear surface of the wafer; a placing step of placing a back surface of the wafer on the support tray; A wafer processing method comprising the steps of:

2. 2. The method for treating a wafer according to claim 1, further comprising a protective tape peeling step of supporting the back surface of the wafer on the support tray used in the transporting step and peeling off the protective tape from the front surface of the wafer.

3. 2. The support tray for use in the wafer processing method according to claim 1, A support tray comprising a support portion having a size corresponding to a recess formed on the rear surface of the wafer, and a step portion formed on the outer periphery of the support portion corresponding to a convex ring-shaped reinforcement portion formed on the rear surface of the wafer.

4. 4. The support tray of claim 3, wherein a resin is laid on an upper surface of the support portion.

5. 4. The support tray according to claim 3, wherein the support portion is formed with a suction portion for suction-holding the recessed portion of the wafer, so that the wafer can be sucked in the protective tape peeling step.

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