Wafer machining method

Abstract

To provide a wafer machining method that prevents the outer periphery of a wafer from being exfoliated and eliminates the need to remove a chamfering part of the wafer prior to grinding.SOLUTION: A wafer machining method includes: a resin embedding step of embedding a water-insoluble resin 20 in a chamfering part 14 adjacent to a bonded interface; a holding step of holding one wafer 4 on a rotatable chuck table of a grinding apparatus; and a grinding step of positioning a grinding wheel in which grinding stones of the grinding apparatus are annularly arranged and which is rotatable, on a surface of the other wafer 6 held on the chuck table, rotating the chuck table while supplying grinding fluid, rotating the grinding wheel to grind the other wafer 6.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a method for processing a wafer in which a wafer having a chamfered portion formed on its outer periphery is bonded to another wafer, and a method for processing a wafer having a chamfered portion formed on its outer periphery. [Background technology]

[0002] A wafer has a number of devices such as ICs and LSIs formed on its surface, separated by planned dividing lines, and its back surface is ground to a specified thickness. The wafer is then divided into individual device chips by a dicing machine, and each of the divided device chips is used in electrical equipment such as mobile phones and personal computers.

[0003] The grinding apparatus includes a chuck table for holding the wafer, a grinding means having a rotatable grinding wheel with grinding stones arranged in a ring shape for grinding the wafer held on the chuck table, a feeding means for feeding the grinding means for grinding, and a measuring means for measuring the thickness of the wafer, and is capable of processing the wafer to the desired thickness.

[0004] However, because a chamfer is formed on the outer periphery of the wafer, when the back surface of the wafer is ground to thin it, the chamfer becomes a sharp knife edge. This can cause cracks to form from the outer periphery of the wafer and extend into the device region, damaging the device and possibly injuring the operator. Therefore, the present applicant has proposed a technique for removing the chamfer before grinding the back surface of the wafer (see, for example, Patent Document 1).

[0005] In addition, in the case of a bonded wafer in which two wafers are bonded together, before the wafers are bonded together, the chamfered portion of one of the wafers, whose back surface is ground, may be removed, and then the front surface of the one wafer from which the chamfered portion has been removed may be laminated on the other wafer. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2016-96295 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, when grinding the back surface of the wafer by rotating the grinding wheel while supplying grinding water, the grinding water accelerated by the rotational force of the grinding wheel attacks the interface (bonding surface) of the bonded wafer, causing the outer periphery of the bonded wafer to peel off. In addition, there is a problem that removing the chamfered portion of the wafer prior to grinding is time-consuming and troublesome.

[0008] An object of the present invention is to provide a wafer processing method which does not cause the outer periphery of the wafer to peel off and does not require removing the chamfered portion of the wafer prior to grinding. [Means for solving the problem]

[0009] According to the present invention, there is provided the following wafer processing method that solves the above problems. "A processing method for a wafer in which a wafer having a chamfered portion formed on the outer periphery is bonded together, a resin embedding step of embedding a water-insoluble resin in a chamfered portion adjacent to the bonded interface; a holding step of holding one of the wafers on a rotatable chuck table of a grinding device; a grinding step in which a rotatable grinding wheel having grinding stones of the grinding device arranged in an annular shape is positioned on a surface of the other wafer held on the chuck table, and the other wafer is ground by rotating the chuck table and rotating the grinding wheel while supplying grinding water; A wafer processing method including the steps of:

[0010] According to the present invention, there is also provided the following wafer processing method which solves the above problems. "A method for processing a wafer having a chamfered portion formed on the outer periphery, a protective member providing step of providing a protective member on a front surface of the wafer; a resin embedding step of embedding a water-insoluble resin in a chamfered portion adjacent to the interface where the protective member is disposed; a holding step of holding the protective member on a rotatable chuck table of a grinding device; a grinding step in which a rotatable grinding wheel having grinding stones of the grinding device arranged in an annular shape is positioned on the back surface of the wafer held on the chuck table, and the chuck table is rotated while supplying grinding water, thereby grinding the back surface of the wafer; A wafer processing method including the steps of: Effect of the Invention

[0011] The wafer processing method of the present invention includes the steps of: A processing method for a wafer in which a wafer having a chamfered portion formed on an outer periphery is bonded, comprising the steps of: a resin embedding step of embedding a water-insoluble resin in a chamfered portion adjacent to the bonded interface; a holding step of holding one of the wafers on a rotatable chuck table of a grinding device; a grinding step in which a rotatable grinding wheel having grinding stones of the grinding device arranged in an annular shape is positioned on a surface of the other wafer held on the chuck table, and the other wafer is ground by rotating the chuck table and rotating the grinding wheel while supplying grinding water; Since the resin protects the bonded wafer from peeling even if the grinding water accelerated by the rotational force of the grinding wheel attacks the interface (bonding surface) of the bonded wafer. Also, according to the present invention, it is not necessary to remove the chamfered portion of the wafer prior to grinding, not only for bonded wafers but also for single wafers, so that the problem of laborious and troublesome grinding is solved. [Brief description of the drawings]

[0012] [Figure 1]FIG. 2A is a schematic diagram showing a state in which one wafer and another wafer are bonded together; FIG. 2B is a perspective view of a bonded wafer in which one wafer and another wafer are bonded together; and FIG. 2C is a partial cross-sectional view of the bonded wafer shown in FIG. 2B. [Diagram 2] (a) A schematic diagram showing the state of arranging a protective member on the surface of a single wafer, (b) an oblique view of the single wafer on which the protective member is arranged, and (c) a partial cross-sectional view of the single wafer shown in (b). [Diagram 3] (a) A partial cross-sectional view of a bonded wafer having a water-insoluble resin embedded in a chamfered portion adjacent to an interface, and (b) a partial cross-sectional view of a single wafer having a water-insoluble resin embedded in a chamfered portion adjacent to an interface where a protective member is disposed. [Figure 4] FIG. [Diagram 5] FIG. [Figure 6] FIG. [Figure 7] (a) A partial cross-sectional view of a bonded wafer where the other wafer has its backside ground, (b) a partial cross-sectional view of a single wafer where its backside has been ground. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, preferred embodiments of the wafer processing method according to the present invention will be described with reference to the drawings.

[0014] The wafer processing method according to the present invention can be carried out on a bonded wafer formed by bonding two wafers together, or on a single wafer.

[0015] (Bonded wafer 2) First, the bonded wafer 2 will be described with reference to FIG. 1. The bonded wafer 2 is formed by bonding a surface 4a of one wafer 4 and a surface 6a of the other wafer 6 together. The disk-shaped one wafer 4 has a thickness of about 700 μm and can be made of an appropriate semiconductor material such as silicon. As shown in FIG. 1(a), the surface 4a of the one wafer 4 is partitioned into a plurality of rectangular regions by a lattice-shaped dividing line 8. A plurality of devices 10 such as ICs and LSIs are formed in the plurality of rectangular regions. In addition, a notch 12 indicating a crystal orientation is formed on the outer periphery of the one wafer 4. As shown in FIG. 1(c), a curved chamfered portion 14 is formed on the outer periphery of the one wafer 4. Note that the other wafer 6 also has dividing lines (not shown), devices (not shown), notches 12, and chamfered portions 14, similar to the one wafer 4.

[0016] When forming the bonded wafer 2, the surface 4a of one wafer 4 and the surface 6a of the other wafer 6 are bonded together by siloxane bonding or the like. At this time, as shown in Fig. 1(b), the notch 12 of one wafer 4 and the notch 12 of the other wafer 6 are aligned, and the wafers are bonded together with the crystal orientation of one wafer 4 and the crystal orientation of the other wafer 6 being aligned.

[0017] (Single wafer 16, protective member placement process) 2 shows a single wafer 16. The single wafer 16 also has dividing lines 8, devices 10, notches 12, and chamfered portions 14, similar to the one wafer 4. When the wafer processing method according to the present invention is carried out on the single wafer 16, a protective member providing step is first carried out in which a protective member 18 is provided on a front surface 16a of the single wafer 16.

[0018] The protective member 18 may be, for example, an adhesive tape made of a synthetic resin having an adhesive layer (glue layer) on one side. The protective member 18 may also be a thermocompression sheet that does not have an adhesive layer. The thermocompression sheet is a sheet of a thermoplastic synthetic resin (for example, a polyolefin resin), which softens or melts and exerts adhesive power when heated to a temperature near the melting point. The shape of the protective member 18 may be a circle having the same diameter as that of a single wafer 16.

[0019] (Resin embedding process) For the bonded wafers 2, after preparing the bonded wafers 2, a resin embedding step is performed in which a water-insoluble resin 20 is embedded in the chamfered portion 14 adjacent to the bonded interface, as shown in Fig. 3(a). For the single wafer 16, after performing the protective member providing step, a resin embedding step is performed in which a water-insoluble resin 20 is embedded in the chamfered portion 14 adjacent to the interface where the protective member 18 is provided, as shown in Fig. 3(b).

[0020] Examples of the water-insoluble resin 20 that can be used in the resin embedding step include epoxy resin and acrylic resin. In addition, it is preferable to use a quick-drying instant adhesive (for example, jelly-like Aron Alpha (registered trademark) manufactured by Toagosei Co., Ltd.) as the water-insoluble resin 20, since this can shorten the working time.

[0021] To explain an example of the resin embedding step, first, the bonded wafers 2 are supported in an upright position, and the central axis of the bonded wafers 2 is made horizontal. Next, while slowly rotating the bonded wafers 2 around the central axis of the horizontally-positioned bonded wafers 2 as a rotation axis, liquid water-insoluble resin 20 is dripped onto the chamfered portion 14 adjacent to the bonded interface from above the bonded wafers 2. Then, the water-insoluble resin 20 dripped onto the chamfered portion 14 is cured. This allows the water-insoluble resin 20 to be embedded over the entire circumference of the chamfered portion 14 adjacent to the bonded interface. The resin embedding step can also be performed on a single wafer 16 in the same manner as described above.

[0022] (holding process) For the bonded wafers 2, after the resin embedding step, a holding step is performed in which one of the wafers 4 is held on a rotatable chuck table of a grinding device. For a single wafer 16, after the resin embedding step, a holding step is performed in which the protective member 18 side is held on a rotatable chuck table of a grinding device. In the holding step, for example, a grinding device 22 shown in FIG. 4 can be used.

[0023] (Grinding device 22) The grinding device 22 includes a chuck table 24 that holds the wafer by suction, a grinding means 26 having a rotatable grinding wheel with grinding stones arranged in a ring shape for grinding the wafer held on the chuck table 24, a feeding means 28 that feeds the grinding means 26 for grinding, and a measuring means (not shown) that measures the thickness of the wafer.

[0024] (Chuck table 24) A circular suction chuck 30 is disposed on the upper end of the chuck table 24. The suction chuck 30 is formed of a porous material such as porous ceramics. The suction chuck 30 is connected to a suction means (not shown). In the chuck table 24, the suction means generates a suction force on the upper surface of the suction chuck 30, and the wafer placed on the upper surface of the suction chuck 30 is suction-held.

[0025] The chuck table 24 is rotated around an axis in the vertical direction by a motor (not shown). Furthermore, the chuck table 24 is moved in the X-axis direction by an X-axis moving means (not shown) between a wafer mounting / removal position (position shown in FIG. 4) and a grinding position (position shown in FIG. 6) below the grinding means 26. The X-axis direction is the direction indicated by the arrow X in FIG. 4.

[0026] (Grinding means 26) The grinding means 26 includes a lift plate 34 supported on a support wall 32 provided at an end (the rear end in FIG. 4) of the grinding device 22 so as to be movable up and down, a protruding member 36 protruding from the lift plate 34, a spindle 38 supported on the protruding member 36 so as to be rotatable about an axis extending in the vertical direction, and a spindle motor 40 for rotating the spindle 38. The spindle 38 has an upper portion penetrating the spindle motor 40. The spindle 38 is formed hollow, and grinding water is supplied to an upper end 38a of the spindle 38 from a grinding water supplying means (not shown). This grinding water is supplied to the wafer and a grinding wheel 48 described below during grinding processing.

[0027] Continuing the explanation with reference to Figure 6, a disk-shaped wheel mount 42 is fixed to the lower end of the spindle 38. An annular grinding wheel 46 is fastened to the underside of the wheel mount 42 by bolts 44. A plurality of grinding stones 48 are fixed to the outer circumferential edge of the underside of the grinding wheel 46, and are arranged annularly at intervals in the circumferential direction.

[0028] (Feeding means 28) 4, the feed means 28 has a ball screw 50 extending in the vertical direction along one surface of the support wall 32, and a motor 52 that rotates the ball screw 50. A nut portion (not shown) of the ball screw 50 is connected to the lift plate 34. The feed means 28 converts the rotational motion of the motor 52 into linear motion by the ball screw 50 and transmits it to the lift plate 34, and feeds the grinding means 26 in the vertical direction for grinding along a guide rail 32a attached to one surface of the support wall 32.

[0029] In the holding step for the bonded wafer 2, first, the X-axis moving means is operated to position the chuck table 24 at the attachment / detachment position shown in Fig. 4. Next, as shown in Fig. 5, the back surface 4b of one wafer 4 is faced downward (the back surface 6b of the other wafer 6 is faced upward) and the bonded wafer 2 is placed on the upper surface of the chuck table 24. Then, the suction means is operated to generate a suction force on the upper surface of the suction chuck 30, causing the chuck table 24 to suction-hold one wafer 4.

[0030] Although not shown, in the holding step for a single wafer 16, first, the chuck table 24 is positioned at the attachment / detachment position. Next, the single wafer 16 is placed on the upper surface of the chuck table 24 with the protective member 18 facing downward. Then, the suction means is operated to generate a suction force on the upper surface of the suction chuck 30, causing the chuck table 24 to suction-hold the protective member 18 side.

[0031] (Grinding process) For the bonded wafer 2, after the holding step, a grinding step is performed in which a rotatable grinding wheel with grinding wheels arranged in an annular shape of a grinding device is positioned on the surface of the other wafer 6 held on the chuck table, and the chuck table is rotated while supplying grinding water, and the grinding wheel is rotated to grind the other wafer 6. For the single wafer 16, after the holding step, a grinding step is performed in which a rotatable grinding wheel with grinding wheels arranged in an annular shape of a grinding device is positioned on the back surface 16b of the single wafer 16 held on the chuck table, and the chuck table is rotated while supplying grinding water, and the grinding wheel is rotated to grind the back surface 16b of the single wafer 16. The grinding step can be performed, for example, by using the grinding device 22 described above.

[0032] In the grinding process for the bonded wafer 2, first, the X-axis moving means is operated to position the chuck table 24 at the grinding position shown in FIG. 6. Next, the spindle 38 is rotated in the direction indicated by the arrow R1 at a predetermined rotation speed (for example, 6000 rpm). The chuck table 24 is also rotated in the direction indicated by the arrow R2 at a predetermined rotation speed (for example, 300 rpm). Next, the spindle 38 is lowered by the feed means 28 to bring the grinding wheel 48 into contact with the back surface 6b of the other wafer 6, and grinding water is supplied to the portion where the grinding wheel 48 is in contact with the back surface 6b. Then, while measuring the thickness of the bonded wafer 2 (the thickness of the other wafer 6) by the measuring means, the spindle 38 is lowered at a predetermined grinding feed speed (for example, 1.0 μm / s), whereby the back surface 6b of the other wafer 6 is ground by the grinding wheel 48, and the other wafer 6 is formed to a predetermined thickness (see FIG. 7(a)). Moreover, the grinding step for the single wafer 16 can be carried out in the same manner as the grinding step for the bonded wafer 2. Fig. 7(b) shows a partial cross-sectional view of the single wafer 16 after the grinding step has been carried out.

[0033] As described above, in this embodiment, the water-insoluble resin 20 is embedded in the chamfered portion 14 adjacent to the bonded interface of the bonded wafers 2, so that even when the other wafer 6 is ground and the grinding water accelerated by the rotational force of the grinding wheel 46 attacks the interface (bonded surface) of the bonded wafers 2, the outer periphery of the bonded wafers 2 does not peel off because it is protected by the water-insoluble resin 20. In addition, since the resin 20 is water-insoluble, it is not removed by the grinding water.

[0034] Furthermore, according to this embodiment, it is not necessary to remove the chamfered portion 14 prior to grinding, not only for the bonded wafer 2 but also for the single wafer 16, so the problem of the laborious and troublesome process is eliminated.

[0035] It is not necessary to remove the resin 20 adhering to the chamfered portion 14 after grinding the surface of the bonded wafer 2 (the back surface 6b of the other wafer 6) or the back surface 16b of the single wafer 16. The reason for this is that after the bonded wafer 2 or the single wafer 16 is divided into the individual device chips 10, the chamfered portion 14 is discarded as an unnecessary area, and therefore the resin 20 adhering to the chamfered portion 14 is also discarded at the same time. [Explanation of symbols]

[0036] 2: Bonded wafer 4: One wafer 4a: Surface of one wafer 4b: Back side of one wafer 6: The other wafer 6a: Surface of the other wafer 6b: Back surface of the other wafer 14: Chamfered part 16: Single wafer 16a: Surface of a single wafer 16b: Backside of a single wafer 18: Protective material 20: Water-insoluble resin 22: Grinding device 24: Chuck table 46: Grinding wheel 48: Grinding wheel

Claims

1. A processing method for a wafer in which a wafer having a chamfered portion formed on an outer periphery is bonded, comprising the steps of: a resin embedding step of embedding a water-insoluble resin in a chamfered portion adjacent to the bonded interface; a holding step of holding one of the wafers on a rotatable chuck table of a grinding device; a grinding step in which a rotatable grinding wheel having grinding stones of the grinding device arranged in an annular shape is positioned on a surface of the other wafer held on the chuck table, and the other wafer is ground by rotating the chuck table and rotating the grinding wheel while supplying grinding water; A wafer processing method comprising the steps of:

2. A method for processing a wafer having a chamfered portion formed on an outer periphery, comprising the steps of: a protective member providing step of providing a protective member on a front surface of the wafer; a resin embedding step of embedding a water-insoluble resin in a chamfered portion adjacent to the interface where the protective member is disposed; a holding step of holding the protective member on a rotatable chuck table of a grinding device; a grinding step in which a rotatable grinding wheel having grinding stones of the grinding device arranged in an annular shape is positioned on the back surface of the wafer held on the chuck table, and the chuck table is rotated while supplying grinding water, thereby grinding the back surface of the wafer; A wafer processing method comprising the steps of:

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