JP2013026380A - Processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the scraps of protective tape from remaining on a wafer, when cutting a protective tape by using a byte.SOLUTION: The processing method includes a protective tape sticking step for sticking a protective tape 7 to a workpiece 1, a holding step for holding the workpiece by a holding table 21 so as to expose the protective tape 7 after the sticking step, and a flattening step for flattening the protective tape 7 stuck to the workpiece 1 by cutting the protective tape 7 with a byte wheel 35 by locating the rotating byte wheel 35 at a predetermined height and moving the holding table 21 and the byte wheel 35 relatively after the holding step. In the flattening step, revolving speed of the byte wheel 35 is set to a peripheral velocity of 1914 m/min. or higher, thus preventing the thread-like scraps of protective tape from remaining on the workpiece.

Description

  The present invention relates to a processing method for cutting and flattening a protective tape attached to a workpiece with a bite wheel.

  When grinding a workpiece such as a wafer, a protective tape is attached to the wafer surface in order to prevent damage to the wafer surface. As a protective tape, what was described in the following patent document 1 can be used, for example.

  However, when the protective tape is attached to the surface of a wafer on which a plurality of protruding connection electrodes called bumps are formed, the surface of the protective tape may be uneven according to the bumps. Accordingly, if the wafer surface is held in this state and the back surface is ground, the flatness of the wafer after grinding becomes extremely low. Therefore, in order to solve this problem, the present applicant cuts the protective tape with a cutting tool proposed in the following Patent Document 2 and flattens it, and then grinds the back surface of the wafer, thereby flattening the wafer. I found a way to thin it well.

JP H5-1985423 JP 2005-333067 A

  However, when the protective tape is cut with a cutting tool, thread-shaped protective tape scraps are generated, and the generated protective tape scraps remain on the protective tape adhered to the wafer surface and wrap around and adhere to the wafer back side. In some cases, it is difficult to remove the protective tape waste even if the wafer is cleaned. In this way, if the protective tape scraps remain attached to the wafer, for example, it may cause problems such as adhesion to the transfer unit of the apparatus during wafer handling, causing wafer transfer failure, and damage to the wafer itself. There is a risk that.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent protective tape waste from remaining on a wafer when the protective tape is cut with a cutting tool.

  The present invention includes a holding table having a holding surface for holding a workpiece, a bite wheel that rotates on a plane parallel to the holding surface and cuts the workpiece held on the holding table, and the holding table. A processing method for flattening a protective tape adhered to a workpiece using a cutting tool provided with a moving means for relatively moving the rotating bite wheel, the protective tape being applied to the workpiece After carrying out the protective tape sticking step to be stuck, the protective tape sticking step, the holding step for holding the workpiece with the holding table so that the protective tape is exposed, and after carrying out the holding step The rotating tape tool is positioned at a predetermined height, and the holding table and the tool wheel are moved relative to each other by the moving means, whereby the protective tape attached to the workpiece is Comprising a planarization step of planarizing by cutting in bytes wheel, and the rotational speed of the byte wheel in planarization step peripheral speed 1914m / min. It is characterized by being set as described above.

  In the present invention, after the flattening step is performed in the processing method, the protective tape side is held by a holding table to expose the workpiece, and the exposed workpiece is ground by a grinding wheel. In addition, a thinning step of thinning to a predetermined thickness can be further provided.

  In the processing method according to the present invention, the rotation speed of the bite wheel is set to the peripheral speed of 1914 m / min. By setting and cutting as described above, it is possible to prevent thread-like protective tape scraps from remaining on the wafer. Accordingly, the protective tape waste does not go around and adhere to the back surface side of the wafer, and it is possible to prevent the wafer from being poorly transported or damaged.

  Further, the rotational speed of the bite wheel is set to a peripheral speed of 1914 m / min. After flattening the protective tape, hold the protective tape side with a holding table and grind the exposed surface of the work piece, and since the protective tape is flattened, the exposed surface of the work piece is also flattened. be able to.

It is a perspective view which shows an example of a cutting tool. It is a perspective view which shows a moving means. It is a top view which shows the wafer which is an example of a to-be-processed object. It is an enlarged front view which shows the wafer before cutting. It is a perspective view which shows a protective tape sticking step. It is a perspective view which shows the state by which the protective tape is stuck on the wafer. It is an expanded sectional view showing the state where a protective tape is stuck on a wafer. It is a front view which shows a holding | maintenance step. It is a front view which shows the planarization step. It is an expanded sectional view which shows the wafer after a cutting process. It is a perspective view which shows a thinning step.

  A cutting tool 10 shown in FIG. 1 is a device in which a workpiece is held by a holding means 20, and the workpiece is cut by a cutting means 30, and a rectangular parallelepiped base extending in the Y-axis direction. 11 and a standing base 12 standing on one end of the upper surface of the base 11. The upper surface of the base 11 includes a supply cassette 13 for storing a workpiece before cutting and a collection cassette 19 for storing the workpiece after cutting.

  In the vicinity of the supply cassette 13 and the recovery cassette 19, a transfer robot 14 that carries out the workpiece from the supply cassette 13 and loads the workpiece into the recovery cassette 19 is disposed. The transfer robot 14 includes a bendable arm 14 a and a hand 14 b provided at the tip of the arm 14 a, and the transfer robot 14 is installed so that the hand 14 b reaches the supply cassette 13 and the recovery cassette 19. A cleaning device 18 for cleaning the workpiece after cutting is disposed in the movable range of the hand 14b.

  Positioning means 15 is provided in the movable range of the hand 14b to align the work piece carried out from the supply cassette 13 by the transport robot 14 at a predetermined position. The positioning means 15 includes a plurality of positioning pins 15a that are arranged on an arc and are movable in the radial direction.

  The holding means 20 moves in the Y-axis direction between an attachment / detachment area P1, which is an area where the workpiece is attached to and detached from the holding means 20, and a cutting area P2, which is an area where the workpiece is actually processed. It is possible. The movement of the holding means 20 between the attaching / detaching area P1 and the cutting area P2 is controlled by the moving means 50 shown in FIG.

  As shown in FIG. 2, the holding means 20 includes a holding table 21 having a holding surface 22 that holds a workpiece, a shaft portion 23 attached to a lower portion of the holding table 21, and a holding table via the shaft portion 23. And a support base 24 for supporting the above. As shown in FIG. 2, the holding means 20 may include an elevating drive unit 25 that can raise and lower the holding table 21.

  As shown in FIG. 2, the moving means 50 includes a ball screw 54 extending in the Y-axis direction, a pair of guide rails 55 arranged in parallel to the ball screw 54, and a motor 56 connected to one end of the ball screw 54. And a ball screw receiving member 57 connected to the other end of the ball screw 54, and a moving base 51 whose inner nut structure is screwed into the ball screw 54 and whose lower part is in sliding contact with the guide rail 55. In the moving means 50 configured as described above, the moving base 51 is guided by the guide rail 55 and moved in the Y-axis direction when the ball screw 54 is rotated by being driven by the motor 56. Yes. As shown in FIG. 1, an accordion-shaped cover 52 is laid on the moving path of the moving base 51 constituting the moving means 50.

  As shown in FIG. 1, between the positioning means 20 and the attachment / detachment area P1, a first transfer means 16 for transferring the workpiece from the positioning means 20 to the holding means 20 located in the attachment / detachment area P1 is disposed. Yes. Between the cleaning means 18 and the attachment / detachment area P1, a second transfer means 17 for transferring the workpiece from the holding means 20 located in the attachment / detachment area P1 to the cleaning means 18 is disposed. The 1st conveyance means 16 and the 2nd conveyance means 17 are provided with the suction pads 16a and 17a which adsorb | suck a workpiece, respectively.

  The cutting means 30 shown in FIG. 1 is connected to a spindle housing 31 extending in the Z-axis direction, a holder 32 for holding the spindle housing 32, a spindle 34 rotatably supported by the spindle housing 31, and an upper end of the spindle 34. And a bite wheel 35 attached to the lower part of the spindle 34, and a bite 36 detachably attached to the bite wheel 35. The bite wheel 35 can rotate on a surface parallel to the holding surface 22 of the holding table 21. Although not shown in the drawing, an outflow portion for allowing cutting water to flow out is formed in the lower portion of the bite wheel 35.

  The cutting means 30 is supported on the side of the upright base 12 via the feeding means 40. The feeding means 40 includes a ball screw 41 extending in the Z-axis direction, a pair of guide rails 42 arranged in parallel to the ball screw 41, a motor 43 connected to one end of the ball screw 41, A ball screw receiving member 46 connected to the end, an elevating base 44 for controlling the height position of the cutting tool 36, and a support member 45 for supporting the cutting means 30 via the holder 32 are provided. A pair of guide rails 42 are in sliding contact with one surface of the elevating base 44, and a nut structure (not shown) is formed in the center portion, and a ball screw 41 is screwed into the nut structure. Then, when the ball screw 41 rotated by the motor 43 is rotated, the lifting base 44 is guided by the guide rail 42 and moves in the Z-axis direction, and the cutting means 30 is also lifted and lowered in the Z-axis direction. be able to.

  Below, an example of the processing method using the cutting tool 10 shown in FIG. 1 is demonstrated.

  The wafer 1 shown in FIG. 3 has a plurality of devices 3 partitioned by streets 4 formed in a lattice shape on the surface 2a. Also, a notch 6 is formed at one end of the outer periphery of the wafer 1 as a mark for identifying the crystal orientation. As shown in the partially enlarged view, bumps 5 that are a plurality of protruding electrodes are formed on the surface of the device 3. As shown in FIG. 4, the bump 5 is formed so as to protrude from the surface 2a, and the height of the bump 5 may be non-uniform in some cases. The amount of protrusion from the surface 2a of the bump is, for example, about 50 to 100 μm.

(1) Protection Tape Affixing Step As shown in FIG. 5, the protection tape 7 is affixed to the surface of the wafer 1. The protective tape 7 includes a base material layer 8 and a glue layer 9, and the glue layer 9 is formed on the lower surface side of the base material layer 8. The base material layer 8 is made of a polyolefin base material, a vinyl chloride base material, a pet (polyethylene terephthalate) base material, or the like, and has a thickness of about 100 to 300 μm. On the other hand, the glue layer 9 is made of a rubber material, an acrylic material, or the like, and has a thickness of about 5 to 100 μm.

  When adhering the protective tape 7 to the wafer 1, as shown in FIG. 5, the adhesive layer 9 side of the protective tape 7 is lowered toward the surface 2 a side of the wafer 1 in the direction of arrow B, and the wafer 1 Adhesive layer 9 is affixed to. Then, as shown in FIG. 6, the protective tape 7 is attached to the surface 2 a of the wafer 1, and the wafer 1 and the protective tape 7 are integrated. When the protective tape 7 is affixed to the wafer 1, as long as the bumps 5 shown in FIG. 4 are not completely embedded in the adhesive layer 9, the base of the protective tape 7 is as much as the protrusion of the bumps 5 as shown in FIG. Protrusions 8a are raised on the surface of the material layer 8, and the protective tape 7 has an irregular shape. A plurality of wafers 1 having the protective tape 7 adhered to the surface 2a in this way are accommodated in the supply cassette 13 shown in FIG.

(2) Holding step After the protective tape attaching step is performed, the wafer 1 to which the protective tape 7 is attached is unloaded from the supply cassette 13 by the transfer robot 14 and transferred to the positioning means 20, and the positioning pins 15a are After the wafers 1 are positioned at a certain position by moving in a direction in which they approach each other, the wafers 1 are moved above the holding table 21 waiting at the attachment / detachment position P1 by the first transfer means 16. Then, as shown in FIG. 8A, the back surface 2b side of the wafer 1 is lowered toward the holding surface 22 of the holding table 21 in the direction of arrow C, and the wafer 1 is placed on the holding table 21, not shown. The back surface 2b side of the wafer 1 is attracted to the holding surface 22 by the suction force generated from the suction source. As a result, as shown in FIG. 8B, the wafer 1 is held in a state where the base material layer 8 side of the protective tape 7 attached to the wafer 1 is exposed upward.

(3) Flattening Step After performing the holding step, the holding means 20 shown in FIG. 1 is moved by the moving means 50 in the direction of the arrow A1 in the Y-axis direction, and the holding table 21 is positioned in the cutting region P2. Specifically, the motor 56 of the moving means 50 shown in FIG. 2 starts to drive, and the ball screw 54 rotated by the motor 56 rotates to guide the moving base 51 to the guide rail 55. It moves in the Y-axis direction, and also moves the holding means table 21 in the Y-axis direction to reach the cutting area P2.

  On the other hand, the bite wheel 35 of the cutting means 30 is also positioned at a predetermined height where the protective tape 7 can be cut. Specifically, when the ball screw 41 rotated by the motor 43 of the feeding means 40 shown in FIG. 1 rotates, the lifting base 44 is guided by the guide rail 42 and moves in the Z-axis direction. The bite wheel 35 is moved in the Z-axis direction, and the bite 36 is positioned at a predetermined height position.

  9, while the bite wheel 35 is rotated, the holding table 21 is moved in the direction of the arrow A1 by the moving means 50 shown in FIG. 2 so that the holding table 21 and the rotating bite wheel 35 are moved along the Y axis. The cutting tool 36 is moved in a direction parallel to the holding surface 21 and circularly moved in a direction parallel to the holding surface 22 of the holding table 21 and cut into the base material layer 8 of the protective tape 7. At this time, for example, cutting is performed so that about half of the thickness of the base material layer 8 is removed. During cutting, cutting water is supplied to the contact portion between the cutting tool 36 and the base material layer 8. When cutting is performed in this manner, the convex portion 8a shown in FIG. 7 is cut away, and the surface of the base material layer 8 is flattened. When the initial thickness of the base material layer 8 is 300 μm, it is scraped off by about 150 μm, which is a half of the thickness. As a result, the convex portion 8a shown in FIG. 7 is scraped off and flattened as shown in FIG. The diameter of the bite wheel 35 is desirably 8 inches, and the rotational speed of the bite wheel 35 is desirably set to, for example, 3000 [RPM] (circumferential speed 1914 [m / min.]) Or more.

  When cutting, thread-like protective tape waste is generated, but the peripheral speed of the bite wheel 35 is set to 1914 m / min. If it is set as above, while the protective tape waste does not remain on the protective tape 7, the height of the protective tape 7 can be made uniform as shown in FIG.

  When the cutting of the protective tape 7 is thus completed, the holding means 20 moves in the direction of the arrow A2 shown in FIG. 1 and returns to the attachment / detachment region P1. Then, the wafer 1 to which the protective tape 7 is attached is attracted to the suction pad 17a of the second transport means 17 and transported to the cleaning means 18, and after cleaning and drying, the wafer 1 is transferred to the hand 14b of the transport robot 14. It is held and accommodated in the collection cassette 19.

  Since the protective tape debris does not remain on the protective tape 7, the protective tape debris does not go around to the back surface 2 b side of the wafer 1, so that the suction pad 17 a of the second conveying means 17 and the hand 14 b of the conveying robot 14 are protected. It is possible to prevent the wafer from being damaged due to the transfer failure without causing the transfer of the wafer due to adhesion of the tape scrap.

(4) Thinning step After the protective tape 7 is flattened by the flattening step, the workpiece is thinned to a predetermined thickness. For thinning the workpiece, for example, a thinning device 60 shown in FIG. 11 can be used.

  The thinning device 60 includes a holding table 60a that holds a workpiece and a grinding unit 60b that grinds the workpiece held on the holding table 60a. The holding table 60a includes a holding portion 66 that holds a workpiece on its surface, and is rotatable. The grinding means 60b includes a spindle 61 having a vertical axis, and a grinding wheel 64 mounted on the lower end of the spindle 61 via a mount 63. The grinding wheel 64 is fixed to the mount 63 by bolts 62. A plurality of grinding wheels 65 are fixed to the lower part of the grinding wheel 64 in an annular shape. Further, the grinding wheel 64 is configured to rotate as the spindle 61 rotates.

  In the thinning device 60, the holding table 60a holds the protective tape 7 attached to the wafer 1, and the back surface 2b of the wafer 1 is exposed upward. Then, the holding table 60a is rotated in the direction of arrow D, the grinding means 60b is lowered while rotating the spindle 61 in the direction of arrow E, and the rotating grinding wheel 65 is brought into contact with the back surface 2b of the rotating wafer 1, thereby back surface 2b. The wafer 1 is thinned. During grinding, the grinding wheel 65 passes through the rotation center of the wafer 1. When the wafer 1 is thinned to a desired thickness, the grinding means 60b is raised to finish grinding.

  In the flattening step, the base material layer 8 of the protective tape 7 is flattened, and no protective tape waste remains on the protective tape 7. Therefore, in the thinning step, the flattened base material layer 8 side is held on the holding table 60a. The back surface 2b of the wafer 1 is ground while being held in FIG. 1, whereby the back surface 2b can be ground flat, and cracking of the wafer can be prevented.

Using the cutting tool 10 shown in FIG. 1, the protective tape 7 was cut under various conditions, and the remaining state of the protective tape waste was visually confirmed. The conditions are as shown in the following (1) to (4).
(1) Wheel diameter of bite wheel: φ8 inch (2) Bite wheel rotation speed (rotational peripheral speed):
Oh, 2000rpm (1276m / min.)
A 2500rpm (1595m / min.)
C) 3000 rpm (1914 m / min.)
D 3500rpm (2233m / min.)
(3) Protective tape substrate:
A Polyolefin base material B Vinyl chloride base material C Pet base material (4) Feed pitch:
Cutting was performed at feed pitches of 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, and 160 [μm]. The feed pitch is a Y-direction relative movement distance between the holding table 21 and the bite wheel 35 per rotation of the bite wheel 35.

  When the rotation speed of the bite wheel 35 is set to the above (2000 rpm (1276 m / min.)) And i (2500 rpm (1595 m / min.)), The base material of the protective tape and the feed pitch are either In addition, it was confirmed that thread-like protective tape scraps remained on the wafer.

  When the rotation speed of the bite wheel 35 is set to c (3000 rpm (1914 m / min.)) And d (3500 rpm (2233 m / min.)), And the feed pitch is set to 70 μm or less, depending on the type of the protective tape substrate Although it was confirmed that a small amount of protective tape scrap remained, it was confirmed that this did not lead to problems such as damage to the wafer itself or occurrence of wafer conveyance failure.

  When the rotational speed of the bite wheel 35 is set to U (3000 rpm (1914 m / min.)) And D (3500 rpm (2233 m / min.)) And the feed pitch is set to 80 μm or more, any protective tape substrate However, no residual protective tape scraps were found on the wafer.

  As the above experimental results show, when the bite wheel 35 rotates at a high peripheral speed, the protective tape scraps on the work piece are caused by the fluid accompanying the bite wheel 35, for example, the pressure or centrifugal force of air or cutting water. It was confirmed that it was easily removed from the surface. Therefore, when the rotation speed of the bite wheel 35 is 3500 rpm (circumferential speed 2233 m / min.) Or more, it is possible to effectively prevent the remaining protective tape waste.

  Further, when the feed pitch is increased, the protective tape waste generated by the cutting of the cutting tool is increased, so that it is easily removed from the workpiece. Therefore, it is desirable to set the feed pitch to 80 μm or more. On the other hand, at a feed pitch of 160 μm, the flatness of the cutting surface of the wafer deteriorated at any protective tape substrate and at any number of rotations. Therefore, it is desirable to set the feed pitch to 80 μm or more and 150 μm or less.

1: Wafer 2a: Front surface 2b: Back surface 3: Device 4: Street 5: Bump 6: Notch 7: Protection tape 8: Base material layer 9: Glue layer 10: Tool cutting device 11: Base 12: Standing base 13 : Supply cassette 14: Workpiece transport robot 14a: Arm 14b: Hand 15: Positioning means 15a: Positioning pin 16: First transport device 16a: Suction pad 17: Second transport device 17a: Suction pad 18: Cleaning device 19: Collection cassette 20: Holding means 21: Holding table 22: Holding surface 23: Shaft part 24: Support base 25: Lifting drive part 30: Cutting means 31: Spindle housing 32: Holding tool 33: Servo motor 34: Spindle 35: Tool Wheel 36 Byte 40: Feed means 41: Ball screw 42: Guide rail 43: Motor 44: Lifting base 5: Support member 46: Ball screw receiving member 50: Moving means 51: Moving base 52: Cover 54: Ball screw 55: Guide rail 56: Motor 57: Ball screw receiving member 60: Thinning device 60a: Holding table 60b: Grinding means 61: Spindle 62: Bolt 63: Mount 64: Grinding wheel 65: Grinding wheel 66: Holding part

Claims (2)

A holding table having a holding surface for holding a workpiece, a bite wheel that rotates on a plane parallel to the holding surface to cut the workpiece held by the holding table, and the bit that rotates with the holding table A processing method for flattening a protective tape attached to a workpiece using a cutting tool provided with a moving means for moving the wheel relative to the workpiece,
A protective tape attaching step for attaching a protective tape to the workpiece;
A holding step of holding the workpiece with the holding table so that the protective tape is exposed after performing the protective tape attaching step;
After carrying out the holding step, the rotating tape tool is positioned at a predetermined height, and the moving means moves the holding table and the tool wheel relative to each other so that the protective tape is attached to the workpiece. And a flattening step for flattening by cutting with the bite wheel,
In the flattening step, the rotational speed of the bite wheel is 1914 m / min. A processing method characterized by being set as described above.   After performing the flattening step, the protective tape side is held by a holding table so that the workpiece is exposed, and the exposed workpiece is ground by a grinding wheel and thinned to a predetermined thickness. The processing method according to claim 1, further comprising a conversion step.

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