Method of processing a wafer

Abstract

The present application provides a wafer processing method without preparing a dummy wafer and without transferring the wafer. The wafer processing method includes the following steps: a holding step of holding the wafer on a chuck table; a dressing step of adjusting a state of a cutting edge by cutting a peripheral remaining area of the wafer with a cutting tool installed on a cutting unit; and a dividing step of dividing the wafer into individual device chips by cutting a dividing predetermined line with the cutting tool installed on the cutting unit.

Description

TECHNICAL FIELD

[0001] The present application relates to a processing method of a wafer which is divided into individual device chips. BACKGROUND

[0002] A wafer which is divided by a plurality of division lines intersecting each other and in which a plurality of devices such as ICs, LSIs, and the like are formed on the front surface is divided into individual device chips by a cutting apparatus having a cutting tool, and the divided device chips are used for electric appliances such as mobile phones, personal computers, and the like.

[0003] The cutting apparatus is configured to include a chuck table which holds the wafer, a cutting unit which is provided with the cutting tool and which is capable of rotating the cutting tool, the cutting tool having a cutting edge which cuts the wafer held by the chuck table on the outer periphery, an X-axis feed mechanism which relatively feeds the chuck table and the cutting unit in the X-axis direction, a Y-axis feed mechanism which relatively feeds the chuck table and the cutting unit in the Y-axis direction which is perpendicular to the X-axis direction, and a Z-axis feed mechanism which feeds the cutting unit in the Z-axis direction which is perpendicular to the X-axis direction and the Y-axis direction, and is capable of dividing the wafer into individual device chips with high precision.

[0004] In addition, in order to adjust the state of the cutting edge of the cutting tool, a wafer in which no device is formed (dummy wafer) is held on the chuck table, and dressing which adjusts the state of the cutting edge by cutting the dummy wafer with the cutting tool and dressing which removes attached matter are performed periodically or at an arbitrary timing (for example, refer to Patent Document 1).

[0005] Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. 11-176772

[0006] In order to perform the above-described dressing, a dummy wafer in which no device is formed must be prepared additionally, and after a predetermined number of times of dressing, a new dummy wafer is required, which is uneconomical, and since the dummy wafer is transferred with respect to the chuck table to perform the dressing, there is a problem that productivity deteriorates. SUMMARY

[0007] Therefore, an object of the present application is to provide a processing method of a wafer which does not require a dummy wafer to be prepared additionally and does not require transfer of the wafer even in the case where a dressing process which adjusts the state of the cutting edge is required.

[0008] According to the present application, there is provided a wafer processing method of dividing a wafer, in which a device region in which a plurality of devices are divided by a plurality of division lines crossing each other and a peripheral remaining region surrounding the device region are formed on a front surface, into individual device chips, the wafer processing method comprising: a preparation step of preparing a cutting device including a chuck table that holds the wafer, a cutting unit to which a cutting tool is attached and that is rotatable, the cutting tool having a cutting edge that cuts the wafer held by the chuck table on a periphery, an X-axis feed mechanism that relatively feeds the chuck table and the cutting unit in an X-axis direction, a Y-axis feed mechanism that relatively indexes the chuck table and the cutting unit in a Y-axis direction perpendicular to the X-axis direction, and a Z-axis feed mechanism that feeds the cutting unit in a Z-axis direction perpendicular to the X-axis direction and the Y-axis direction; a holding step of holding the wafer on the chuck table; a trimming step of adjusting a state of the cutting edge by cutting the peripheral remaining region with the cutting tool attached to the cutting unit after the holding step is performed; and a dividing step of dividing the wafer into individual device chips by cutting the division lines with the cutting tool attached to the cutting unit.

[0009] Preferably, in the trimming step, the cutting unit is fed in the Z-axis direction to vertically cut into the peripheral remaining region, and the cutting edge of the cutting tool is adjusted.

[0010] According to the present application, in the wafer processing method, even in the case of the trimming step in which the state of the cutting edge needs to be adjusted, a dummy wafer does not need to be prepared, and furthermore, the wafer does not need to be reloaded due to the trimming step, and thus the productivity is improved. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 is a perspective view of a wafer that is a workpiece of the present embodiment.

[0012] Figure 2 is an overall perspective view of a cutting device suitable for the wafer processing method of the present embodiment.

[0013] Figure 3 is a perspective view that enlarges a part of the cutting device in the embodiment of the trimming step.

[0014] Figure 4 (a) of Figure 3 is a side view of the trimming step shown in Figure 4 (b) is a side view showing another embodiment of the trimming step shown in Figure 4 (a).

[0015] Figure 5 (a) is implemented Figure 3 A three-dimensional view of the wafer undergoing the finishing process shown. Figure 5 (b) is a perspective view of a wafer that has undergone a finishing process according to another embodiment. Figure 5 (c) is a perspective view of a wafer that has undergone a finishing process according to another embodiment.

[0016] Label Explanation

[0017] 1: Cutting device; 2: Stationary base; 4: Spindle support mechanism; 8: Spindle unit; 81: Imaging component; 9: Cutting unit; 91: Z-axis moving base; 92: Spindle housing; 92a: Rotary axis; 93: Cutting tool; 93a: Cutting edge; 95: Tool cover; 96: Cutting water supply nozzle; 10: Wafer; 10A: Device area; 10a: Front side; 10B: Remaining peripheral area; 10b: Back side; 12: Device; 14: Segmentation pre- 1. Linear alignment; 20: Holding unit; 24: Chuck table; 30: X-axis feed mechanism; 31: Pulse motor; 32: Ball screw; 40: Y-axis moving base; 42: Support; 43: Vertical wall; 44: Guide rail; 50: Y-axis feed mechanism; 51: Pulse motor; 52: Ball screw; 60: Z-axis feed mechanism; 61: Pulse motor; 100, 110a, 100b, 120: Cutting groove; F: Frame; T: Protective belt. Detailed Implementation

[0018] Hereinafter, a wafer processing method according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0019] exist Figure 1 The image shows a wafer 10 processed by the wafer processing method of this embodiment. The wafer 10 has a device region 10A formed on its front side 10a, which is divided into multiple devices 12 by intersecting predetermined dividing lines 14, and a peripheral remaining region 10B surrounding the device region 10A. Figure 1 As shown, in this embodiment, the wafer 10 is positioned at the center of the opening Fa formed in the annular frame F, and the back surface 10b is attached to the protective strip T attached to the outer periphery of the frame F and supported by the frame F.

[0020] exist Figure 2A perspective view of a cutting apparatus 1 suitable for implementing a wafer processing method according to the present application is shown in FIG. 1. The cutting apparatus 1 of the present embodiment has a holding unit 20. The holding unit 20 has a rectangular X-axis direction moving base 21 supported so as to be movable on a pair of guide rails 2a, 2a disposed in parallel along the X-axis direction on a stationary base 2, a cylindrical support member 22 disposed on the X-axis direction moving base 21, a rectangular cover plate 23 covering the periphery of the upper portion of the cylindrical support member 22, a chuck table 24 disposed on the cylindrical support member 22 to hold a wafer 10, and a clamping mechanism 26 disposed between the cylindrical support member 22 and the chuck table 24 to hold the frame F when the wafer 10 is placed on the chuck table 24 to be held. A pair of guide grooves 21a, 21a that abut on the guide rails 2a, 2a in a slidable manner are formed on the lower surface of the X-axis direction moving base 21, and a sliding portion is formed by the guide rails 2a, 2a and the guide grooves 21a, 21a. The chuck table 24 is composed of a member having air permeability, and is connected to a suction source (not shown) through the inside of the cylindrical support member 22. By operating the suction source, a suction negative pressure is supplied to the holding surface of the chuck table 24.

[0021] The cutting apparatus 1 is composed of a cutting unit 9 having a cutting tool 93 mounted thereon and rotatable, the cutting tool 93 having a cutting edge 93a on the outer periphery to cut the wafer 10 held by the chuck table 24, an X-axis feed mechanism 30 to relatively process feed the chuck table 24 and the cutting unit 9 in the X-axis direction, a Y-axis feed mechanism 50 to relatively index feed the chuck table 24 and the cutting unit 9 in the Y-axis direction perpendicular to the X-axis direction, and a Z-axis feed mechanism 60 to relatively plunge feed the chuck table 24 and the cutting unit 9 in the Z-axis direction perpendicular to the X-axis direction and the Y-axis direction. Although not shown, a rotation drive mechanism to rotate the chuck table 24 is disposed in the inside of the cylindrical support member 22, and the chuck table 24 can be rotated at a desired angle.

[0022] The X-axis feed mechanism 30 converts the rotational motion of a pulse motor 31 into linear motion via a ball screw 32 rotated by the pulse motor 31, and transmits the linear motion to the X-axis direction moving base 21 on which the chuck table 24 is disposed, and makes the X-axis direction moving base 21 advance and retreat along the pair of guide rails 2a, 2a on the stationary base 2.

[0023] A main shaft support mechanism 4 is provided on the stationary base 2, and is configured to be movable in the Y-axis direction by a Y-axis feed mechanism 50. The main shaft support mechanism 4 has a Y-axis direction movement base 40 having a support portion 42 supported so as to be movable on a pair of rails 2b, 2b extending in the Y-axis direction, and a vertical wall portion 43 provided upright on the support portion 42. A pair of guide grooves 42a, 42a that abut on the rails 2b, 2b in a slidable manner are formed on the lower surface of the support portion 42, and a sliding portion is formed by the rails 2b, 2b and the guide grooves 42a, 42a. The Y-axis feed mechanism 50 converts the rotational motion of a pulse motor 51 into linear motion via a ball screw 52 that rotates by the pulse motor 51, and transmits the linear motion to the support portion 42, causing the support portion 42 to advance and retreat in the Y-axis direction along the rails 2b, 2b on the stationary base 2.

[0024] A main shaft unit 8 is mounted on the vertical wall portion 43 of the Y-axis direction movement base 40, and is configured to be movable in the Z-axis direction indicated by an arrow Z1 by a Z-axis feed mechanism 60. The main shaft unit 8 has a Z-axis direction movement base 91, a main shaft housing 92 supported by the Z-axis direction movement base 91, a cutting unit 9 having a cutting tool 93 supported so as to be rotatable by the main shaft housing 92 and provided at the front end portion of a rotation axis 92a in the Y-axis direction, and a photographing member 81 provided on the main shaft housing 92. The cutting tool 93 of the cutting unit 9 is positioned in the X-axis direction at a prescribed position (for example, a center position) of a region photographed by the photographing member 81.

[0025] The Z-axis direction movement base 91 is supported so as to be movable along a pair of rails 44, 44 provided on the vertical wall portion 43 of the Y-axis direction movement base 40 in the Z-axis direction indicated by the arrow Z1 (a cutting feed direction). A pair of guide grooves 91a (only one is shown in the drawing) that abut on the rails 44, 44 in a slidable manner are provided on the Z-axis direction movement base 91. The Z-axis direction movement base 91 is moved in the Z-axis direction by a pulse motor 61 of the Z-axis feed mechanism 60 and a ball screw (omitted from the drawing) that converts the rotation of the pulse motor 61 into linear motion and transmits the linear motion to a female screw portion formed in the Z-axis direction movement base 91. The pulse motor 61 and the ball screw function as the Z-axis feed mechanism 60 that relatively feeds the holding unit 20 and the cutting unit 9 in the Z-axis direction.

[0026] As Figure 3As shown, the cutting unit 9 has a rotary shaft 92a provided at the front end of the main shaft housing 92, held rotatable by the main shaft housing 92, and rotationally driven by an electric motor not shown; a cutting tool 93 fixed to the front end of the rotary shaft 92a; a tool cover 95 covering the cutting tool 93; a cutting water supply port 97 supplying cutting water through the tool cover 95; and a cutting water supply nozzle 96 spraying cutting water to a cutting machining position with an annular cutting edge 93a of the cutting tool 93.

[0027] A control unit not shown is provided in the cutting apparatus 1. The control unit is constituted by a computer, has a central processing unit (CPU) that performs arithmetic processing according to a control program, a read-only memory (ROM) that stores the control program and the like, a random access memory (RAM) that is writable and readable and temporarily stores detected values, arithmetic results, and the like, an input interface, and an output interface. The control unit is connected to the pulse motor 31 of the X-axis feed mechanism 30, the pulse motor 51 of the Y-axis feed mechanism 50, the pulse motor 61 of the Z-axis feed mechanism 60, a rotary drive mechanism not shown that rotates the chuck table 24, and the like, and can position the chuck table 24 and the cutting tool 93 of the cutting unit 9 at desired positions based on position information detected by position detection members that detect the positions of the X-axis and rotational directions of the chuck table 24 and the positions of the Y-axis and Z-axis directions of the cutting tool 93 of the cutting unit 9.

[0028] The cutting apparatus 1 has substantially the above-described structure, and a wafer processing method of the present embodiment implemented using the cutting apparatus 1 will be described below.

[0029] In implementing the wafer processing method of the present embodiment, a preparation process of preparing the above-described cutting apparatus 1 is implemented. As the cutting apparatus prepared in this preparation process, as described above, as long as it is a cutting apparatus constituted to include a chuck table 24 that holds a wafer 10, a cutting unit 9 that is provided with a cutting tool 93 rotatable and has a cutting edge 93a on the outer periphery that cuts the wafer 10 held by the chuck table 24, an X-axis feed mechanism 30 that relatively feeds the chuck table 24 and the cutting unit 9 in the X-axis direction, a Y-axis feed mechanism 50 that relatively feeds the chuck table 24 and the cutting unit 9 in the Y-axis direction perpendicular to the X-axis direction, and a Z-axis feed mechanism 60 that feeds the cutting unit 9 in the Z-axis direction perpendicular to the X-axis and Y-axis directions, the other structures are not limited to the above-described cutting apparatus 1.

[0030] Next, as Figure 2 As shown, a holding process is performed to hold the wafer 10 on the chuck stage 24. In this holding process, the wafer 10 is placed on the chuck stage 24 through the protective belt T, and a suction source (not shown) is activated to perform suction holding, and the frame F is fixed by the clamping mechanism 26.

[0031] Next, a trimming process is performed to adjust the state of the cutting edge 93a by cutting the remaining peripheral region 10B of the wafer 10 using the cutting tool 93 mounted on the cutting unit 9. This trimming process can be performed based on the position information of the remaining peripheral region 10B of the wafer 10 stored in the control unit. However, the present invention is not limited to this. For example, before performing the trimming process, the X-axis feed mechanism 30 and the Y-axis feed mechanism 50 can be activated to position the chuck stage 24 directly below the imaging member 81, and the wafer 10 held by the chuck stage 24 can be imaged to detect the position information of the remaining peripheral region 10B of the wafer 10.

[0032] The following is for reference Figures 3 to 5 The specific implementation method of the finishing process is explained. Additionally, Figures 3 to 5 This indicates that the chip 10 is held on the chuck stage 24, but for ease of explanation, the chuck stage 24 and other structures are omitted.

[0033] During the finishing process, firstly, the cutting unit 9 is activated, causing the cutting tool 93 to rotate in the direction indicated by arrow R1. Next, based on the position information of the remaining peripheral region 10B of the wafer 10 stored in the control unit, the X-axis feed mechanism 30 and the Y-axis feed mechanism 50 are activated, causing the chuck table 24 and the cutting unit 9 to move relative to each other, positioning the cutting unit 9 on the protective strip T outside the remaining peripheral region 10B of the wafer 10. Then, the pulse motor 61 of the Z-axis feed mechanism 60 is activated, causing the cutting tool 93 (indicated by solid lines) to rotate towards... Figure 4 The cutting tool 93 descends in the direction indicated by arrow R2 in (a). At this time, the lower end position of the descending cutting tool 93 is set to the height of the front side of the protective strip T or slightly higher. If the cutting tool 93 descends, the wafer 10 moves in the direction indicated by arrow X, causing the cutting tool 93 to cut from the outer peripheral end of the wafer 10 into the remaining outer peripheral region 10B (indicated by a double-dotted line), forming... Figure 3 The cut groove 100 shown is shown.

[0034] After the aforementioned groove 100 is formed, the Z-axis feed mechanism 60 is activated to raise the cutting tool 93, and the X-axis feed mechanism 30 is activated to move the wafer 10 along the X-axis, positioning the cutting tool 93 on the protective strip T outside the remaining peripheral region 10B of the wafer 10. Then, the Y-axis feed mechanism 50 is activated to index the wafer 10 and the cutting unit 9 relative to each other along the Y-axis, positioning the cutting tool 93 adjacent to the previously formed groove 100. Then, similarly, the cutting tool 93 is lowered, and the wafer 10 is moved along the X-axis to form a new groove 100. This process of forming the groove 100 is repeated until the cutting edge 93a is neat, as described above. Figure 5 As shown in (a), multiple cutting grooves 100 are formed. Thus, in the remaining peripheral region 10B where the device 12 is not formed, by cutting the cutting tool 93 to a predetermined length, it avoids cutting into the film stacked on the front surface 10a of the device region 10A, or components called TEGs formed at the predetermined dividing line 14. Therefore, the state of the cutting edge 93a is adjusted, and the cutting edge 93a is trimmed. Furthermore, as... Figure 5 As shown in (a), when multiple cutting grooves 100 are formed along the direction of the predetermined dividing line 14, it is preferable to form them in areas that avoid the extension line of the predetermined dividing line 14. As a result, in the subsequent dividing process, when cutting is performed along the predetermined dividing line 14, it is possible to prevent the pre-formed cutting grooves 100 from obstructing the travel of the cutting tool 93.

[0035] Furthermore, in the aforementioned finishing process, the cutting tool 93 is positioned on the protective strip T outside the remaining peripheral region 10B of the wafer 10. While the wafer 10 is moved along the X-axis, the cutting tool 93 cuts in horizontally, forming a groove 100 in the remaining peripheral region 10B of the wafer 10. However, for example, it can also be done as follows: Figure 4 As shown in (b), the cutting tool 93 is positioned on the outer peripheral remaining region 10B of the wafer 10. The cutting unit 9 is activated to rotate the cutting tool 93 in the direction indicated by arrow R1, and the cutting tool 93 is fed along the Z-axis direction indicated by arrow R2, cutting vertically into the outer peripheral remaining region 10B from above to form a cutting groove 100, thereby adjusting the cutting edge 93a. In this case, it is also preferable to activate the Y-axis feed mechanism 50 to index the wafer 10 and the cutting unit 9 relative to each other along the Y-axis direction, while forming multiple cutting grooves 100 in the outer peripheral remaining region 10B.

[0036] Furthermore, the trimming process of the present invention is not limited to the above-described embodiments; for example, it can also be implemented as described above. Figure 5As shown in (b), the wafer 10 is cut in the peripheral remaining region 10B by a cutting tool 93 in a manner that forms a chord connecting two points on the outer periphery of the crystal sheet 10. Preferably, the state of the cutting edge 93a is adjusted by forming a plurality of indentation grooves 110a parallel to this chord. Alternatively, to better adjust the state of the cutting edge 93a, the wafer 10 can be rotated 90 degrees in the direction indicated by arrow R3 in the figure, and the cutting tool 93 can be positioned on an adjacent peripheral remaining region 10B to cut in a manner that forms a chord connecting two points on the outer periphery of the crystal sheet 10, thereby forming a plurality of indentation grooves 110b.

[0037] In addition, such as Figure 5 As shown in (c), multiple drill grooves 120 can also be formed radially in the remaining peripheral region 10B of the wafer 10. When forming the drill grooves 120, the X-axis feed mechanism 30 and the Z-axis feed mechanism 60 are activated, causing the cutting tool 93 to cut into the remaining peripheral region 10B of the wafer 10 along the X-axis direction (horizontal direction) or the Z-axis direction (vertical direction) to form the drill grooves 120. The rotary drive mechanism of the chuck stage 24 (not shown) is activated, causing the wafer 10 to gradually rotate in the direction indicated by arrow R3 to form multiple drill grooves 120 radially, thereby enabling the trimming process to be performed.

[0038] After performing the above-mentioned trimming process, the following slicing process is performed: the cutting unit 9 is activated, and the X-axis feed mechanism 30, Y-axis feed mechanism 50 and Z-axis feed mechanism 60 are activated. The cutting tool 93 installed on the cutting unit 9 is used to cut all the predetermined slicing lines 14 of the wafer 10, thereby slicing the device 12 of the wafer 10 into individual device chips.

[0039] According to this embodiment, in the wafer processing method, even when performing a trimming process to adjust the state of the cutting edge 93a, it is not necessary to prepare a virtual wafer, and therefore it is not necessary to transfer the wafer due to the trimming process, thus improving productivity.

Claims

1. A wafer processing method, wherein a wafer having a device region on its front side divided into multiple devices by intersecting predetermined dividing lines and a remaining peripheral region surrounding the device region is divided into individual device chips, wherein, The wafer fabrication method includes the following steps: The preparation process involves preparing a cutting device comprising a chuck table, a cutting unit, an X-axis feed mechanism, a Y-axis feed mechanism, and a Z-axis feed mechanism. The chuck table holds the wafer. The cutting unit is equipped with a cutting tool that can rotate. The cutting tool has a cutting edge on its outer periphery for cutting the wafer held by the chuck table. The X-axis feed mechanism feeds the chuck table and the cutting unit relative to each other along the X-axis direction. The Y-axis feed mechanism feeds the chuck table and the cutting unit relative to each other along the Y-axis direction, which is perpendicular to the X-axis direction. The Z-axis feed mechanism feeds the cutting unit along the Z-axis direction, which is perpendicular to both the X-axis and Y-axis directions. The holding process involves holding the wafer on the chuck stage. The finishing process involves adjusting the cutting edge state by cutting the remaining outer peripheral area using a cutting tool mounted on the cutting unit after the holding process; and The dicing process uses cutting tools mounted on the cutting unit to cut along predetermined dicing lines to divide the wafer into individual device chips.

2. The wafer processing method according to claim 1, wherein, In this dressing process, the cutting unit is fed along the Z-axis and cuts vertically into the remaining area of ​​the outer periphery, and the cutting edge of the cutting tool is adjusted.

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