JP7084845B2 - Wafer manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a wafer.

For processing semiconductor wafers, for example, one large-diameter wafer or a plurality of small-diameter wafers are manufactured by hollowing out one large-diameter wafer with a core drill having a diameter smaller than the diameter. There is processing. Then, the strength can be ensured by chamfering the outer peripheral portion of the hollowed out small diameter wafer.

Japanese Patent Application Laid-Open No. 2017-003265

The conventional processing as described above consists of a two-step process of hollowing out a large-diameter wafer to manufacture a small-diameter wafer and then chamfering the hollowed-out small-diameter wafer, resulting in low productivity. I have a problem.
An object of the present invention is to improve productivity when a small diameter wafer is hollowed out from a large diameter wafer and the outer peripheral portion is chamfered.

The present invention is a method for manufacturing a wafer from a large-diameter wafer to a small-diameter wafer, which comprises a tape sticking step of sticking a tape on one surface of the large-diameter wafer and chucking the large-diameter wafer through the tape. The holding process of holding on a table and the processing of cutting the annular grindstone arranged at the tip of the cylindrical base from the other side of the large-diameter wafer and hollowing out the small-diameter wafer from the large-diameter wafer, and at the same time, the inside of the cylindrical base. A punching step of chamfering the first corner where the other surface and the side surface of the small-diameter wafer are in contact with the chamfering grinds arranged in the above, and the small-diameter wafer hollowed out in the hollowing step. It is a wafer manufacturing method including an acquisition step of peeling from a tape, and a second chamfering step of chamfering a second corner where one surface of the small-diameter wafer and the side surface are in contact with each other after the acquisition step.

In the above-mentioned wafer manufacturing method, an outer diameter correction grind for correcting the outer shape of the small diameter wafer is brought into contact with the outer periphery of the small diameter wafer, and the diameter size of the small diameter wafer is corrected to a preset diameter size. It is desirable to include an outer shape correction step of performing either the uneven surface correction for correcting the roughness of the surface, or the diameter size correction and the uneven surface correction.

In the wafer manufacturing method, the protective layer forming step of forming a protective layer on one surface and the other surface of the large-diameter wafer before the tape attaching step and the protective layer after the second chamfering step. It is desirable to include a protective layer removal step for removing the above.

In the present invention, there is an effect of shortening the processing time by simultaneously performing the hollowing process and the chamfering process.

It is a perspective view which shows the whole processing apparatus. It is a perspective view which shows the appearance of a core drill. It is a partially broken perspective view showing the inside of a core drill. It is sectional drawing which shows the state of the hollowing process. It is sectional drawing which shows the large diameter wafer. It is sectional drawing which shows the large diameter wafer in which the protective layer was formed. It is sectional drawing which shows the large diameter wafer to which the protective tape was attached. It is sectional drawing which shows the state of the hollowing process. It is sectional drawing which shows the state that the core drill is separated from a large diameter wafer after a hollowing process. It is sectional drawing which shows the wafer acquisition process. It is sectional drawing which shows the state that the 2nd chamfering process is performed after the external shape correction process. It is sectional drawing which shows the state that the outer diameter correction process is performed after the 2nd chamfering process. It is sectional drawing which shows the protective layer removal process.

1 Wafer configuration As shown in FIG. 1, the large-diameter wafer W, which is a workpiece, is a substantially disk-shaped plate-shaped work made of, for example, silicon or the like. The large diameter wafer W includes one surface Wb, the other surface Wa, and a side surface Wc.

On the large-diameter wafer W, for example, a protective layer R such as an oxide film for preventing chipping may be formed by sandwiching the large-diameter wafer W from the front and back.

The protective tape T is attached to one surface side of the large-diameter wafer W before processing by a protective tape attaching device or the like (not shown). The protective tape T includes a glue layer T1 and a tape base T2, and the glue layer T1 of the protective tape T is attached to the protective layer R formed on the large-diameter wafer W.

The large-diameter wafer W to which the protective tape T is attached is hollowed out by the processing apparatus 1, so that the small-diameter wafer W1 is formed. During the hollowing process, the first corner C1 of the small diameter wafer W1 is chamfered while the small diameter wafer W1 is formed. Here, the first angle C1 refers to a portion corresponding to the ridge line W1d between the other surface W1a and the side surface W1c of the small diameter wafer W1. Further, the second corner C2 refers to a similar portion on the opposite side of the first corner C1, that is, a portion corresponding to the ridge line W1e of one surface W1b and the side surface W1c, and is formed on the second corner C2 after the hollowing process. It is also chamfered. The configuration of the processing apparatus 1 used for the hollowing process is described below.

2 Configuration of the processing device In the processing device 1 shown in FIG. 1, the core drill 74 is cut into the large-diameter wafer W held on the chuck table 30, and the large-diameter wafer W is hollowed out to form the small-diameter wafer W1. This is a device for chamfering by grinding the first angle C1.

The front side (-Y direction side) on the base 10 of the processing apparatus 1 is an area where the large-diameter wafer W to which the protective tape T is attached is attached to and detached from the chuck table 30 attached to the holding means 31. The detachable region A is the region A, and the rear portion (+ Y direction side) on the base 10 is a processing region where the large-diameter wafer W held on the chuck table 30 by the hollowing means 7 is hollowed out. It is B.

The processing device 1 includes a control means 6 composed of storage elements such as a CPU and a memory, and the control means 6 controls the entire device. The control means 6 is connected to the hollow feed means 5 and the positioning means 2 shown in FIG. 1 by a wiring (not shown), and under the control of the control means 6, the hollow feed operation of the hollow feed means 7 by the hollow feed means 5 is performed. Further, the positioning operation of the chuck table 30 in the Y-axis direction by the positioning means 2, the rotational movement of the chuck table 30, and the like are controlled.

A column 11 is erected in the processing region B, and a hollow feeding means 5 for moving the hollowing means 7 in a direction away from or close to the chuck table 30 is arranged on the side surface of the column 11 on the −Y direction side. It is set up. The hollow feeding means 5 is connected to a ball screw 50 having an axial center in the vertical direction (Z-axis direction), a pair of guide rails 51 arranged in parallel with the ball screw 50, and the upper end of the ball screw 50 to rotate the ball screw 50. It is provided with a motor 52 for making the motor 52, an elevating plate 53 in which an internal nut is screwed into a ball screw 50 and a side portion is in sliding contact with a guide rail 51, and a holder 54 which is connected to the elevating plate 53 and holds a hollowing means 7. When the 52 rotates the ball screw 50, the elevating plate 53 is guided by the guide rail 51 and reciprocates in the Z-axis direction, and the hollowing means 7 held by the holder 54 is hollowed out and fed in the Z-axis direction. It is composed.

The chuck table 30 is surrounded by a waterproof cover 39 from the surroundings, is attached to a holding means 31 arranged below the chuck table 30, and is rotatably supported around the axis in the Z-axis direction by the holding means 31. ing. Further, a bellows cover 391 that expands and contracts in the Y-axis direction is connected to the waterproof cover 39. The waterproof cover 39 and the bellows cover 391 play a role of covering the contact portion between the core drill 74 and the large-diameter wafer W and the cleaning water supplied around the contact portion so as not to enter the inside of the base 10 during the hollowing process. ..

The chuck table 30 includes a suction unit 300 that sucks and holds the large-diameter wafer W to which the protective tape T is attached, and a frame body 301 that surrounds and supports the suction unit 300. The upper surface of the suction portion 300 is a holding surface 300a for holding the large-diameter wafer W, and the upper surface of the frame body 301 is a reference surface 301a having the same height as the holding surface 300a. A suction source 37 is disposed below the chuck table 30, and the large-diameter wafer W is suction-held by the holding surface 300a of the suction portion 300 of the chuck table 30 by the suction force exerted by the suction source 37.

The holding means 31 arranged below the chuck table 30 rotates at a predetermined angle with, for example, a bottomed cylindrical casing 310 and a rotating portion 311 that rotates the chuck table 30 around the center of the chuck table 30. A stop unit 312 for stopping the unit 311 is provided.

The bottom surface side of the casing 310 is fixed to the upper surface of the movable block 23, and the bottom surface side of the chuck table 30 is mounted on the upper end side of the casing 310 via a bearing (not shown). The rotating portion 311 housed inside the casing 310 includes, for example, a rotating shaft 311a whose upper end is fixed to the bottom surface side of the chuck table 30, and a motor 311b for rotating the rotating shaft 311a. The center of rotation of the chuck table 30 is located on the axis axis extending in the Z-axis direction of the rotating shaft 311a, and the lower end side of the rotating shaft 311a is connected to a shaft (not shown) that transmits the output of the motor 311b. ..

As shown in FIG. 1, a positioning means 2 for reciprocating the holding means 31 in the radial direction (Y-axis direction in FIG. 1) of the large-diameter wafer W held by the chuck table 30 is built in the base 10. Has been done. The positioning means 2 is, for example, a ball screw 20 having an axial center in the Y-axis direction, a holding base 24 on which the ball screw 20 is arranged, and a pair of guide rails 21 arranged on the holding base 24 in parallel with the ball screw 20. It is composed of a motor 22 for rotating the ball screw 20 and a movable block 23 in which an internal nut is screwed into the ball screw 20 and the bottom thereof is in sliding contact with the guide rail 21. When the motor 22 rotates the ball screw 20, the movable block 23 is guided by the guide rail 21 and moves in the Y-axis direction, and the holding means 31 arranged on the movable block 23 moves the movable block 23. As a result, it moves in the Y-axis direction.

The hollowing means 7 for hollowing out the large-diameter wafer W held on the chuck table 30 includes a spindle 70 whose axial direction is vertical (Z-axis direction), a housing 71 that rotatably supports the spindle 70, and a spindle 70. A motor 72 for rotationally driving the spindle 70, a circular plate-shaped mount 73 connected to the lower end of the spindle 70, and a core drill 74 detachably connected to one surface of the mount 73 are provided.

As shown in FIGS. 2 to 4, the core drill 74 is, for example, a cylindrical base 740 connected to the mount 73, and a cylindrical cylinder that hangs down from the outer circumference of the disc base 740 and the lower end side is released and the upper end side is closed. A base 741 is provided, and an annular grindstone 742 is disposed on the lower end surface of the annular base of the cylindrical base 741 over the entire circumference. The annular grindstone 742 is, for example, formed by electrodepositing abrasive grains on the tip of a cylindrical base 741. The cylindrical base 741 rotated by the motor 72 is moved toward the large-diameter wafer W held by the chuck table 30 by the hollow feeding means 5, whereby the annular grindstone 742 included in the cylindrical base 741 is moved toward the large-diameter wafer W. The small diameter wafer W1 is hollowed out by cutting into the other surface Wa of the above.

Further, inside the cylindrical base 741 of the core drill 74, an inclined surface 743 having an outer peripheral side lower than the inner peripheral side is formed on the lower surface of the cylindrical base 741. The inclined surface 743 has the shape of the side surface of the conical table, and a large number of abrasive grains are electrodeposited on the surface to form the first chamfering grindstone 744. The rotation of the cylindrical base 741 by the motor 72 causes the inclined surface 743 to rotate in the same manner, and the rotating inclined surface 743 descends in the −Z direction while contacting the first corner C1 of the small diameter wafer W1 to have a small diameter. The first corner C1 of the wafer W1 will be chamfered.

The cylindrical base 741 is formed with inlets and outlets 42 penetrating in the thickness direction at equal intervals in the circumferential direction of the cylindrical base 741. The acquisition port 42 in the illustrated example has a long slit shape in the Z-axis direction, but is not limited to this shape.
For example, a grinding water nozzle 40 is disposed outside the core drill 74, and the grinding water can be sprayed toward the core drill 74. The sprayed grinding water enters the inside of the cylindrical base 741 from the slit-shaped inlet / outlet 42 provided in the cylindrical base 741, travels through the inner inclined surface 743, and again from the inlet / outlet 42 to the cylindrical base 741. It is a mechanism that flows out to the outside of.

As shown in FIG. 3, on the upper portion of the inclined surface 743, for example, instead of the grinding water nozzle 40 shown in FIG. 2, the grinding water is supplied from the grinding water supply source 43 to the inside of the cylindrical base 741. The supply port 44 may be provided. The grinding water flowing in from the supply port 44 is transmitted through the inclined surface 743 and drained from the inlet / outlet 42.

3 Wafer manufacturing method The core drill 74 provided in the processing apparatus 1 is used to hollow out the large-diameter wafer W to form the small-diameter wafer W1 while chamfering the first corner C1 of the small-diameter wafer W1 and then chamfering the first corner C1 of the small-diameter wafer W1. By chamfering the corner C2 of 2, a high-strength small-diameter wafer W1 is manufactured. The following is a series of manufacturing methods.

(Protective layer forming process)
Before hollowing out or chamfering the large-diameter wafer W as shown in FIG. 5, one surface Wb and the other surface Wa of the large-diameter wafer W are protected in advance as shown in FIG. By forming the layer R, the occurrence of chipping is prevented. For example, an example of the protective layer R formed on the large-diameter wafer W includes a resist film, an oxide film, and the like. For example, the protective layer R is formed by a method such as steam oxidation or dry oxidation by an oxidizing apparatus (not shown).

(Tape application process)
As shown in FIG. 7, the protective tape T is attached to the large-diameter wafer W on which the protective layer R is formed in the protective layer forming step by using a protective tape attaching means (not shown) or the like. The glue layer T1 of the protective tape T is attached to the protective layer R formed on the large-diameter wafer W. Then, the large-diameter wafer W is supported by the annular frame F via the protective tape T, which improves the handleability when the large-diameter wafer W is conveyed to the chuck table 30 in the next step or later.

(Holding process)
As shown in FIG. 7, the large-diameter wafer W to which the protective tape T is attached is held on the chuck table 30. At that time, the large-diameter wafer W is gripped by an arm or the like (not shown) and conveyed to the chuck table 30, and is placed so that the center of the chuck table 30 and the center of the large-diameter wafer W coincide with each other. ..

(Cutout process)
As shown in FIG. 8, the core drill 74 is hollowed out and fed to the large-diameter wafer W held on the chuck table 30, so that the annular grindstone 742 provided on the cylindrical base 741 cuts into the large-diameter wafer W. As a result, the annular grindstone 742 of the cylindrical base 741 hollows out the large-diameter wafer W to form the small-diameter wafer W1, while the first chamfering grindstone 744 provided on the inner inclined surface 743 of the cylindrical base 741 is the first corner. It abuts on C1 and chamfers the first corner C1. At this time, the annular grindstone 742 cuts into the glue layer T1 of the protective tape T, so that the small diameter wafer W1 can be completely hollowed out from the large diameter wafer W.

In the above-mentioned hollowing step, one small-diameter wafer W1 may be hollowed out from one large-diameter wafer W, or a plurality of small-diameter wafers W1 may be hollowed out from one large-diameter wafer W. When a plurality of small-diameter wafers W1 are hollowed out from one large-diameter wafer W, the number of small-diameter wafers W1 to be formed on the same circumference of the large-diameter wafer W is determined in advance, and each one of the small-diameter wafers W1 is hollowed out according to the number of small-diameter wafers W1. A method is conceivable in which the chuck table 30 is rotated by a predetermined angle to form the number of small diameter wafers W1 on the same circumference of the large diameter wafer W.

Regarding the processing of forming a plurality of small diameter wafers W1 from one large diameter wafer W, for example, when it is desired to form 10 small diameter wafers W1 on the same circumference of the large diameter wafer W, a chuck is used for each hollowing process. Rotate the table 30 by 36 degrees. That is, the rotation angle of the same angle is determined. At this time, in the rotation control of the chuck table 30, for example, the control means 6 transmits a signal for rotation, whereby the motor 311a is driven to rotate the rotating portion 311 around the rotating shaft 311b in the vertical direction. It is done by. Then, after rotating 36 degrees, the control means 6 transmits a rotation stop signal, whereby the stop unit 312 stops the rotation of the rotation unit 311 to stop the rotation of the chuck table 30. After that, a series of processing such as hollowing out the portion adjacent to the hollowed out portion of the large-diameter wafer W can be considered.

By using this processing method, it is possible to simultaneously form the small-diameter wafer W1 and chamfer the first angle C1 of the formed small-diameter wafer W1. This makes it possible to shorten the time required for manufacturing and improve the efficiency of manufacturing.

(Acquisition process)
As described above, after forming a plurality of small-diameter wafers W1 by hollowing out from one large-diameter wafer W, the core drill 74 is moved upward by the hollow-out feeding means 5 as shown in FIG. 9, and the core drill 74 is moved upward from the large-diameter wafer W. Separate. Then, as shown in FIG. 10, the small diameter wafer W1 is pulled up one by one using the pickup device 8 and peeled off from the protective tape T. The pickup device 8 includes an elevating means 81 and a suction unit 82. The small diameter wafer W1 is sucked and held by the suction force exerted by the suction unit 82, and the suction unit 82 is raised by the elevating means 81 to raise the small diameter wafer. By pulling up W1, the small diameter wafer W1 is peeled off from the glue layer T1 of the protective tape T attached to the small diameter wafer W1.
Further, the small-diameter wafer W1 that supports only the annular frame F and is suction-held by the suction portion 82 may be pushed up from below via the protective tape T to facilitate the peeling of the small-diameter wafer W1 from the glue layer T1.

(External shape correction process)
Next, the outer shape of each small diameter wafer W1 acquired in the acquisition step is corrected by using the outer shape correction device 9 shown in FIG. The external shape correction device 9 includes an external shape correction grind 90 and a rotating shaft 91, and as shown in FIG. 11A, the acquired small diameter wafer W1 is collected by the suction portion 82 of the pickup device 8 and the external shape correction device 9. The outer shape correction grind 90, which is sandwiched between the rotating shaft 91 and rotated around the rotating shaft 91 by the power of a motor or the like (not shown), is brought into contact with the side surface W1c of the small diameter wafer W1. Correct the outer shape. The correction of the outer diameter includes the diameter size correction for correcting the size of the diameter and the uneven surface correction for correcting the roughness of the unevenness formed on the side surface. In the outer diameter correction step, both the diameter size correction and the uneven surface correction are performed, or at least one of the corrections is performed.

(Second chamfering process)
After modifying the outer shape, a second chamfering step is performed as shown in FIG. 11 (b). Similar to the above outer diameter correction step, the small diameter wafer W1 is sandwiched between the suction unit 82 and the rotating shaft 91, and the small diameter wafer W1 is sucked and held by the suction unit 82 while the small diameter wafer W1 is driven by a motor or the like (not shown). While rotating around the rotation shaft 91, the second chamfering grindstone 100, which is also rotated by a motor or the like (not shown), is brought into contact with the second corner C2 to chamfer the second corner C2. By tilting the rotation axis 101 of the second chamfering grindstone 100, the shape of the surface formed in contact with the second angle C2 of the small diameter wafer W1 can be adjusted, and the chamfered portion formed by chamfering is predetermined. It can be made into a size or a predetermined shape.

As shown in FIG. 12, after the acquisition step, a second chamfering step may be performed, and then an outer shape correction step may be performed. That is, the order of implementation of the outer shape correction step and the second chamfering step does not matter.

(Protective layer removal process)
As shown in FIG. 13, after chamfering of both the first corner C1 and the second corner C2 of the small diameter wafer W1 is completed, the protective layer R formed on the small diameter wafer W1 using the release liquid L Perform the removal. At that time, for example, the protective layer R formed on the small-diameter wafer W1 is removed by immersing the small-diameter wafer W1 on which the protective layer R is formed in a dedicated container 12 filled with the release liquid L for a predetermined time. I do. At this time, the stripping solution L may be, for example, a mixed solution of concentrated sulfuric acid and hydrogen peroxide solution (SPM) or a mixed solution of ammonia and hydrogen peroxide solution (APM).

1: Processing equipment 10: Base 11: Column A: Detachable area B: Processing area 2: Transportation means 20: Ball screw 21: Guide rail 22: Motor
23: Movable block 24: Holding stand
30: Chuck table 300: Holding surface 301: Reference surface
31: Holding means 310: Casing 311: Rotating part 311a: Rotating shaft 311b: Motor 312: Stop part 37: Suction source 39: Cover 391: Bellows cover 40: Grinding water nozzle 42: In / out port 43: Grinding water supply source 44: Supply port 5: Chamfer feeding means 50: Ball screw 51: Guide rail 52: Motor 53: Elevating plate 54: Holder 6: Control means 7: Chamfering means 70: Spindle 71: Housing 72: Motor 73: Mount 74: Core drill 740: Disk Base 741: Cylindrical base 742: Circular grindstone 743: Inclined surface 744: First chamfering grindstone 8: Pickup device 81: Elevating means 82: Suction source
9: External shape correction device 90: External shape correction grind 91: Rotating shaft 100: Second chamfering grind 101: Rotating shaft 12: Container W: Large diameter wafer Wa: The other surface of the large diameter wafer Wb: One of the large diameter wafers Surface Wc: Side surface of large diameter wafer W1: Small diameter wafer W1a: The other surface of the small diameter wafer W1b: One surface of the small diameter wafer W1c: Side surface of the small diameter wafer
W1d: Ridge line between the other surface and the side surface of the small diameter wafer
W1e: Ridge line between one surface and the side surface of the small diameter wafer C1: First angle C2: Second angle R: Protective layer L: Stripping liquid
T: Protective tape T1: Glue layer T2: Tape base F: Circular frame

Claims (3)

A wafer manufacturing method for manufacturing small diameter wafers from large diameter wafers.
The tape attachment process of attaching tape to one surface of a large-diameter wafer,
A holding process of holding a large-diameter wafer on a chuck table via the tape,
The annular grindstone arranged at the tip of the cylindrical base is cut from the other surface side of the large diameter wafer, and the small diameter wafer is hollowed out from the large diameter wafer, and at the same time, the chamfer arranged inside the cylindrical base is chamfered. A hollowing process in which a first chamfering process is performed with a grindstone to chamfer the first corner where the other surface and the side surface of the small diameter wafer are in contact with each other.
In the acquisition process of peeling the small diameter wafer hollowed out in the hollowing process from the tape,
After the acquisition step, a chamfering step of chamfering a second corner where the one side of the small diameter wafer and the side surface are in contact with each other.
Wafer manufacturing method consisting of. A diameter correction grind that corrects the outer shape of the small diameter wafer is brought into contact with the outer circumference of the small diameter wafer to correct the diameter size of the small diameter wafer to a preset diameter size. The method for manufacturing a wafer according to claim 1, further comprising an external shape correction step of performing the correction, or the diameter size correction and the uneven surface correction. A protective layer forming step of forming a protective layer on one surface and the other surface of the large-diameter wafer before the tape attaching step,
After the chamfering step, a protective layer removing step of removing the protective layer and a step of removing the protective layer
The method for manufacturing a wafer according to claim 1.

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