Processing method of original wafer

Abstract

To provide a processing method for primitive wafer capable of efficiently processing a primitive wafer.SOLUTION: A method for processing a primitive wafer generated from an ingot includes: a step which holds a primitive wafer 10 on a rotary chuck table 61 provided with a holding surface 63 holding an object to be processed; a first grinding step which brings grinding means 4 rotatably provided with a grinding wheel 45 where grinding stones 46 are annularly arranged opposite to a holding surface 63 close to the chuck table 61, rotates the grinding wheel 45 so that the grinding stones 46 pass a rotation center of the primitive wafer 10 held by the chuck table 61 and grinds one surface 10a of the primitive wafer 10; a step which relatively moves the chuck table 61 and the grinding means 4 in the direction parallel to the holding surface 63 and positions the grinding stone 46 at an outer peripheral corner part 10c of one surface 10a; and a first chamfering step which applies chamfering to an outer periphery of one surface 10a of the primitive wafer 10 with the grinding stones 46.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a method for processing an original wafer, which processes an original wafer produced from an ingot. [Background technology]

[0002] Wafers on the top surface of silicon substrates are partitioned along planned division lines into multiple devices such as ICs and LSIs. These are then separated into individual device chips using dicing equipment and laser processing equipment. These are then used in electrical devices such as mobile phones and personal computers.

[0003] Furthermore, so-called original wafers before devices are formed on the surface are produced by slicing an ingot of silicon or the like to a thickness of about 1 mm using a cutting device equipped with an inner diameter blade, a wire saw, etc. (See, for example, Patent Document 1). Both sides of the original wafer produced from the ingot are then ground, and the outer circumferential corners are then chamfered using a dedicated jig, thereby processing the wafer into a state suitable for forming devices on the upper surface. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 08-155948 Summary of the Invention [Problem to be solved by the invention]

[0005] In the conventional processing method for original wafers, a grinding process must be carried out before devices can be formed on the surface of the wafer, and then multiple processes such as chamfering must be carried out using dedicated equipment and jigs, resulting in poor productivity.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and a main technical object of the present invention is to provide a method for processing an original wafer that can efficiently process the original wafer. [Means for solving the problem]

[0007] In order to solve the above-mentioned main technical problem, according to the present invention, there is provided a processing method for a primitive wafer, which processes a primitive wafer generated from an ingot and has no devices formed on either its front or back surface, comprising the steps of: holding the primitive wafer on a rotatable chuck table having a holding surface for holding a workpiece; bringing a grinding means, which is provided with a rotatable grinding wheel having grinding stones arranged in an annular shape facing the holding surface, close to the chuck table; a first grinding step of rotating the grinding wheel so that the grinding wheel passes through the center of rotation of the original wafer held by a chuck table, thereby grinding one side of the original wafer; a first outer periphery positioning step of relatively moving the chuck table and the grinding means in a direction parallel to the holding surface, thereby positioning the grinding wheel at an outer periphery corner of the one side; and a first chamfering step of chamfering the outer periphery of the one side of the original wafer with the grinding wheel, The process is carried out The present invention provides a method for processing an original wafer, in which an outer corner portion of a grinding wheel for grinding one side of the original wafer is positioned at an outer peripheral corner portion of one side of the original wafer after the processing, and the grinding wheel is moved toward the outer periphery of one side of the original wafer while approaching the chuck table, and during this time, the corner portion is brought into contact with the outer peripheral corner portion to grind the outer peripheral corner portion and form a chamfered portion on one side.

[0008] The method further includes a second grinding step of holding the ground surface on the chuck table and rotating the grinding wheel so that the grinding wheel passes through the center of rotation of the original wafer held on the chuck table to grind the other surface of the original wafer, a second outer periphery positioning step of relatively moving the chuck table and the grinding means in a direction parallel to the holding surface to position the grinding wheel at an outer periphery corner of the other surface, and a second chamfering step of chamfering the outer periphery of the other surface of the original wafer with the grinding wheel, and the second chamfering step is The process is carried out It is also possible to position a corner portion of the circumference of a grinding wheel for grinding the other side of the original wafer at the outer circumferential corner portion of the other side of the original wafer after the processing, and move the grinding wheel toward the chuck table while moving it toward the outer circumferential direction of the other side of the original wafer, while bringing the corner portion into contact with the outer circumferential corner portion during this process, thereby grinding the outer circumferential corner portion and forming a chamfered portion on the other side. Effect of the Invention

[0009] The processing method of the present invention is a processing method of a primitive wafer for processing a primitive wafer that is generated from an ingot and has no devices formed on either the front or back surface, and includes a primitive wafer holding step of holding the primitive wafer on a rotatable chuck table having a holding surface for holding a workpiece, and a grinding means having a rotatable grinding wheel with grinding stones arranged in an annular shape facing the holding surface, approaching the chuck table, and grinding the primitive wafer held by the chuck table. the grinding wheel is rotated so that the grinding wheel passes through the rotation center of the original wafer held in the grinding machine, thereby grinding one side of the original wafer; the chuck table and the grinding means are moved relatively in a direction parallel to the holding surface to position the grinding wheel at an outer periphery corner of the one side; and the first chamfering process is performed on the outer periphery of the one side of the original wafer with the grinding wheel, and the first chamfering process is performed on the outer periphery of the one side of the original wafer by the grinding wheel. The process is carried outA corner portion of the outer periphery of a grinding wheel for grinding one side of the original wafer is positioned at the outer periphery corner of one side of the original wafer after grinding has been performed, and the grinding wheel is moved toward the periphery of one side of the original wafer while approaching the chuck table, and during this time the corner portion is brought into contact with the outer periphery corner, thereby grinding the outer periphery corner to form a chamfer on one side.Therefore, the grinding process for grinding the front or back side of the original wafer and the chamfering process for chamfering the outer periphery of the front or back side can be performed in succession without changing processing equipment or tools, thereby improving productivity. [Brief description of the drawings]

[0010] [Figure 1] 1 is an overall perspective view of a grinding device capable of carrying out the processing method of the present embodiment; [Diagram 2] 1 is a perspective view showing an embodiment of a primitive wafer holding step. FIG. [Diagram 3] FIG. 2 is a perspective view showing an embodiment of a first grinding step. [Figure 4] FIG. 2A is a perspective view showing an embodiment of a first chamfering step, and FIG. 2B is a schematic cross-sectional view showing the process shown in FIG. 2A. [Diagram 5] FIG. 13 is a perspective view showing an embodiment of a second grinding step. [Figure 6] FIG. 1A is a perspective view showing an embodiment of a second chamfering step, and FIG. 1B is a schematic cross-sectional view showing the process shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a method for processing an original wafer according to the present invention will be described in detail with reference to the accompanying drawings.

[0012] An overall perspective view of a grinding apparatus 1 suitable for carrying out the processing method for an original wafer according to the present embodiment is shown in Fig. 1. The grinding apparatus 1 shown in Fig. 1 includes an apparatus housing 2 having a substantially rectangular parallelepiped shape, an upright wall 3 erected on the rear end side of the apparatus housing 2, a grinding means 4 for grinding a workpiece, and a chuck table mechanism 6 for holding the workpiece.

[0013] As shown in the figure, the chuck table mechanism 6 includes a chuck table 61 including a disk-shaped suction chuck 61a and a frame 61b surrounding the suction chuck 61a and configured to be rotatable by a rotation drive source (not shown), and a cover plate 62 that projects the chuck table 61 upward and covers the periphery of the chuck table 61. The suction chuck 61a is formed of a porous material having air permeability and is connected to a suction source (not shown). By operating the suction source, negative pressure is supplied to a holding surface 63 of the suction chuck 61a, and a workpiece placed on the holding surface 63 can be suction-held.

[0014] A moving means (not shown) for moving the chuck table mechanism 6 in the direction indicated by the Y-axis in the drawing is accommodated inside the device housing 2. By operating the moving means, the chuck table mechanism 6 can be moved between a carry-in / out area at the front side in the drawing (in the direction indicated by the arrow Y1) where an unmachined workpiece is placed on the chuck table 61 and a processing area at the back side in the drawing (in the direction indicated by the arrow Y2) where the workpiece held on the chuck table 61 is subjected to grinding by the grinding means 4.

[0015] The grinding means 4 is disposed on the front surface of the upright wall 3. The grinding means 4 is mounted on a movable base 4a, and the movable base 4a is engaged on its rear surface side with a pair of guide rails 31, 31 disposed on the upright wall 3 of the device housing 2, and is mounted so as to be slidable in the Z-axis direction (up and down direction) relative to the guide rails 31, 31 in the figure.

[0016] The grinding means 4 includes a spindle housing 42 supported by a support portion 4b formed integrally with the movable base 4a, a rotating spindle 43 rotatably held by the spindle housing 42, and an electric motor 41 disposed as a rotation drive means for the rotating spindle 43. The lower end of the rotating spindle 43 protrudes toward the lower end side of the spindle housing 42, and a wheel mount 44 is disposed on the lower end. A grinding wheel 45 is attached to the lower surface of the wheel mount 44, and a plurality of grinding stones 46 are disposed in an annular shape on the lower surface of the grinding wheel 45 so as to face the holding surface 63 of the chuck table 61 when the chuck table 61 is positioned in the processing area directly below the grinding wheel 45. Grinding water L supplied from a grinding water supply means (not shown) is introduced from the upper end 43a of the rotating spindle 43 and is supplied to the processing area from the center of the lower end surface of the grinding wheel 45 through a passage in the rotating spindle 43.

[0017] The grinding device 1 shown in Fig. 1 includes a grinding feed means 7 that moves the grinding means 4 in the Z-axis direction (the direction perpendicular to the holding surface 63 of the chuck table 61) along the pair of guide rails 31, 31. The grinding feed means 7 includes a male screw rod 71 that is disposed on the front side of the upright wall 3 and extends in the vertical direction, and a pulse motor 72 as a drive source for rotating the male screw rod 71. The male screw rod 71 has its upper and lower ends rotatably supported by the upright wall 3, and an output shaft of the pulse motor 72 is connected to the upper end of the male screw rod 71. A screw connection part (not shown) is formed on the rear surface of the moving base 4a, and a female screw hole extending in the vertical direction is formed in the connection part, and the male screw rod 71 is screwed into the female screw hole. The grinding feed means 7 consisting of such a screw mechanism can rotate the pulse motor 72 in the forward direction to lower the grinding means 4 together with the movable base 4a, and can rotate the pulse motor 72 in the reverse direction to raise the grinding means 4 together with the movable base 4a.

[0018] The grinding device 1 is equipped with a control means (not shown), to which the grinding means 4, grinding feed means 7, the moving means (not shown), etc. are connected, and each means is precisely controlled based on an arbitrary control program.

[0019] The grinding apparatus 1 shown in FIG. 1 has a configuration generally as described above, and the method for processing an original wafer according to this embodiment, which is carried out using the grinding apparatus 1, will be described below.

[0020] 2 shows a silicon (Si) original wafer 10, which is the workpiece of this embodiment. The original wafer 10 is, for example, a circular plate-shaped wafer with a diameter of about 100 mm cut to a thickness of about 1 mm by slicing a cylindrical single crystal ingot (not shown), and is a wafer with no devices or the like formed on either the front or back surface.

[0021] When carrying out the processing method of the original wafer of this embodiment, the original wafer 10 is placed and held on a holding surface 63 of a chuck table 61 positioned in the carry-in / out area with one surface 10a facing upward and the other surface 10b facing downward, as shown in Fig. 2 (original wafer holding step). At this time, the original wafer 10 is placed so that the center of the original wafer 10 coincides with the center of the chuck table 61, and the original wafer 10 is sucked and held on the holding surface 63 of the chuck table 61 by operating a suction source (not shown) to supply negative pressure to the holding surface 63. Note that after being cut out from the ingot, the original wafer 10 of this embodiment is in a state in which neither the front surface nor the back surface is processed, and there is no distinction between the front surface and the back surface, but for convenience of explanation, the surface to be processed first is referred to as "one surface" and the opposite surface is referred to as "the other surface".

[0022] After the above-mentioned original wafer holding step is performed, the moving means is operated to move the chuck table 61 to the processing area in the direction indicated by the arrow Y2 in Fig. 1, the grinding feed means 7 is operated to bring the grinding means 4 close to the chuck table 61, and the grinding wheel 45 is positioned so that the grinding stone 46 passes through the rotation center O of the original wafer 10 held on the chuck table 61 as shown in Fig. 3. Then, the electric motor 41 of the grinding means 4 is operated to rotate the grinding wheel 45 in the direction indicated by the arrow R1 at, for example, 6000 rpm, and the chuck table 61 is rotated in the direction indicated by the arrow R2 at, for example, a rotation speed of 300 rpm, and further, the grinding feed means 7 is operated to bring the grinding means 4 into contact with one surface 10a of the original wafer 10 in the direction indicated by the arrow R3 at a descending speed of, for example, 1.0 μm / sec, thereby grinding one surface 10a of the original wafer 10 by a predetermined amount (first grinding step). It is preferable that the first grinding step is carried out while detecting the amount of grinding using a thickness detection means (not shown).

[0023] After carrying out the first grinding process described above, as shown in FIG. 4(a), the chuck table 61 and the grinding means 4 are moved relatively in a direction parallel to the holding surface 63 of the chuck table 61 (in this embodiment, the chuck table 61 is moved in the direction indicated by the arrow Y1), and the corner portion 46a of the grinding wheel 46 is positioned at the outer peripheral corner portion 10c of one surface 10a (first outer peripheral positioning process).

[0024] After the first outer periphery positioning step is performed, a first chamfering step is performed in which the grinding wheel 46 chamfers the outer periphery corner 10c of one surface 10a of the original wafer 10. In the first chamfering step, the corner portion 46a of the grinding wheel 46 is positioned at the outer periphery corner 10c of one surface 10a of the original wafer 10, and then the grinding wheel 46 is lowered in the direction indicated by the arrow R3 so as to approach the chuck table 61, while the chuck table 61 is moved in the direction indicated by the arrow Y1. This causes the grinding wheel 46 to move in the outer periphery direction of one surface 10a of the original wafer 10, that is, in the direction indicated by the arrow R4 in FIG. 4(b), so as to escape. As a result, the outer periphery corner 10c is ground to form a chamfered portion 11 at the outer periphery corner 10c of the one surface 10a, and the first chamfering step is completed. The first chamfering process of this embodiment is performed consecutively to the first grinding process, and the grinding wheel 46 and the chuck table 61 of the grinding means 4 are performed while maintaining their rotation during the first grinding process. However, the present invention is not limited to this, and the rotation of the grinding wheel 46 and the chuck table 61 may be temporarily stopped when moving from the first grinding process to the first chamfering process. In addition, the chamfered portion 11 formed in this embodiment is formed as a tapered surface having a linear cross section as shown in FIG. 4(b), but it is also possible to form the chamfered portion 11 so that the cross section is curved by adjusting the descending speed of the grinding wheel 46 and the moving speed of the chuck table 61 in the Y1 direction when performing the first chamfering process.

[0025] According to the above-mentioned processing method for the original wafer, the first grinding step of grinding one surface 10a of the original wafer 10 and the first chamfering step of chamfering the outer periphery of the one surface 10a can be carried out in succession without changing the processing device or jig, thereby improving productivity.

[0026] According to the processing method for an original wafer of this embodiment, after carrying out the above-mentioned first grinding step and first chamfering step, it is also possible to carry out the second grinding step and second chamfering step described below.

[0027] After the first grinding step and the first chamfering step described above have been performed, the moving means is operated to move the chuck table 61 to the loading / unloading area and the suction source is stopped. The original wafer 10 is removed from the chuck table 61 and turned over, and placed on the holding surface 63 of the chuck table 61 with the other side 10b of the original wafer 10 facing upward and one side 10a facing downward so that the center of the chuck table 61 and the center of the original wafer 10 coincide with each other. The suction source is then operated to hold the original wafer 10 by suction to the chuck table 61 (this is the same process as that described based on FIG. 2, except for the difference between the front and back).

[0028] Next, the moving means is operated to move the chuck table 61 to the processing area in the direction indicated by the arrow Y2 in Fig. 1, and the grinding feed means 7 is operated to bring the grinding means 4 close to the chuck table 61, and the grinding wheel 45 is positioned so that the grinding stone 46 passes the center O of the original wafer 10 held on the chuck table 61, as shown in Fig. 5. Then, the electric motor 41 of the grinding means 4 is operated to rotate the grinding wheel 45 in the direction indicated by the arrow R1 at, for example, 6000 rpm, and the chuck table 61 is rotated in the direction indicated by the arrow R2 at, for example, a rotational speed of 300 rpm, and further, the grinding feed means 7 is operated to bring the grinding means 4 into contact with the other surface 10b of the original wafer 10 in the direction indicated by the arrow R3 at a descending speed of, for example, 1.0 μm / sec, to grind the other surface 10b of the original wafer 10 by a predetermined amount (second grinding step).

[0029] After carrying out the second grinding process described above, as shown in FIG. 6(a), the chuck table 61 and the grinding means 4 are moved relatively in a direction parallel to the holding surface 63 of the chuck table 61 (in this embodiment, the chuck table 61 is moved in the direction indicated by the arrow Y1), and the corner portion 46a of the grinding wheel 46 is positioned at the outer peripheral corner portion 10d of the other surface 10b (second outer peripheral positioning process).

[0030] After the second outer periphery positioning step is performed, a second chamfering step is performed in which the grinding wheel 46 is used to chamfer the outer periphery corner 10d of the other side 10b of the original wafer 10. In the second chamfering step, the outer periphery corner 46a of the grinding wheel 46 is positioned at the outer periphery corner 10d of the other side 10b of the original wafer 10, and then the grinding wheel 46 is lowered in the direction indicated by the arrow R3 so as to approach the chuck table 61, while the chuck table 61 is moved in the direction indicated by the arrow Y1. As a result, the grinding wheel 46 is moved in the outer periphery direction of the other side 10b of the original wafer 10, that is, in the direction indicated by the arrow R4 in FIG. 6(b) so as to escape. As a result, the outer periphery corner 10d is ground to form a chamfered portion 12 at the outer periphery corner 10d of the other side 10b, and the second chamfering step is completed. The second chamfering process of this embodiment is carried out successively to the second grinding process, similar to the first grinding process and the first chamfering process described above, and is carried out while the grinding wheel 46 of the grinding means 4 and the chuck table 61 are maintained rotating during the second grinding process. Also, the chamfered portion 12 formed by this embodiment can be formed to have a curved cross section, similar to the chamfered portion 11 described above.

[0031] According to the above-mentioned second grinding process and second chamfering process, the second grinding process for grinding the other surface 10b of the original wafer 10 and the second chamfering process for chamfering the outer periphery of the other surface 10b can be carried out in succession without changing the processing device or jig, thereby improving productivity. [Explanation of symbols]

[0032] 1: Grinding device 2: Device housing 3: Upright wall 31: Guide rail 4: Grinding method 4a: Mobile base 4b: Support part 41: Electric motor 42: Spindle housing 43: Rotating spindle 44: Wheel mount 45: Grinding wheel 46: Grinding wheel 46a: Corner 6: Table mechanism 61: Chuck table 61a: Suction chuck 61b: Frame 62: Cover table 63: Holding surface 7: Grinding feed means 71: Male threaded rod 72: Pulse motor 10: Original wafer 10a: One side 10b: The other side 10c: Outer corner 10d: Outer periphery 11, 12: Chamfered section

Claims

1. A method for processing an original wafer, which is generated from an ingot and has no devices formed on either its front or back surface, comprising the steps of: an original wafer holding step of holding the original wafer on a rotatable chuck table having a holding surface for holding a workpiece; a first grinding step in which a grinding means having a rotatable grinding wheel with grinding stones arranged annularly facing the holding surface is brought close to the chuck table, and the grinding wheel is rotated so that the grinding stones pass through a rotation center of the original wafer held on the chuck table, thereby grinding one surface of the original wafer; a first outer periphery positioning step of relatively moving the chuck table and the grinding means in a direction parallel to the holding surface to position the grinding wheel at an outer periphery corner of one surface; a first chamfering process step of chamfering an outer periphery of one surface of the original wafer with the grinding wheel; The first chamfering process is a processing method for an original wafer in which an outer corner portion of a grinding wheel for grinding one side of the original wafer is positioned at an outer peripheral corner portion of one side of the original wafer after the first grinding process is performed, and the grinding wheel is moved toward the chuck table while approaching the chuck table, and during that time, the corner portion is brought into contact with the outer peripheral corner portion to grind the outer peripheral corner portion and form a chamfer on one side.

2. a second grinding step of holding the ground surface on the chuck table and rotating the grinding wheel so that the grinding wheel passes through a rotation center of the original wafer held on the chuck table to grind the other surface of the original wafer; a second outer periphery positioning step of relatively moving the chuck table and the grinding means in a direction parallel to the holding surface to position the grinding wheel at an outer periphery corner of the other surface; a second chamfering process step of chamfering the outer periphery of the other surface of the original wafer with the grinding wheel; 2. The method for processing an original wafer according to claim 1, wherein the second chamfering process includes positioning an outer corner portion of a grinding wheel for grinding the other side of the original wafer at an outer peripheral corner portion of the other side of the original wafer after the second grinding process is performed, and moving the grinding wheel toward the periphery of the other side of the original wafer while approaching the chuck table, and during that time, bringing the corner portion into contact with the outer peripheral corner portion to grind the outer peripheral corner portion and form a chamfer portion on the other side.

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