JP6025325B2 - Wafer grinding method - Google Patents

Description

  The present invention relates to a wafer grinding method for grinding a wafer, in particular, a wafer including a chamfered portion located on the outer periphery and a flat portion located inward of the chamfered portion, and a wafer grinding apparatus for performing such a method. .

  In the semiconductor manufacturing field, wafers tend to increase in size year by year, and the wafers are becoming thinner to increase the mounting density. In order to reduce the thickness of the wafer, so-called back grinding is performed to grind the back surface of the wafer.

  As is well known, a chamfered portion is formed on the outer periphery of the wafer to prevent dust generation, and the cross section at the wafer edge is narrower toward the tip. In recent years, since it is required to perform a large back surface grinding, the back surface grinding may be performed in excess of half the thickness of the wafer. In such a case, a tapered portion that is thinner than the thickness of the wafer after back grinding is formed on the outer periphery of the wafer.

  Since this tapered portion is fragile, cracks are likely to occur in the tapered portion. And a crack may spread to the inside of a wafer. Therefore, in order to suppress the formation of cracks, edge trimming is performed to remove the chamfered portion of the wafer before grinding the wafer.

  Patent Document 1 discloses edge chamfering of a wafer by a rotating blade. In Patent Document 1, after edge trimming of a chamfered portion of a wafer, the turntable is rotated to move the wafer to a grinding unit, and the flat portion of the wafer is ground by the grinding unit.

JP 2007-165802 A

  However, in the method of Patent Document 1, a rotating blade for removing the chamfered portion and a motor for driving the rotating blade are required. In Patent Document 1, since the wafer is moved by the turntable, the position of the wafer cannot be finely adjusted.

  Instead of finely adjusting the position of the wafer, Patent Document 1 requires a separate positioning mechanism unit for positioning the rotating blade. That is, in Patent Document 1, a rotating blade, a motor for the rotating blade, and a positioning mechanism are required. Therefore, in patent document 1, there existed a problem that the whole apparatus enlarged.

  The present invention has been made in view of such circumstances, and performs wafer grinding for performing both removal of a chamfered portion of a wafer and grinding of a flat portion of a wafer without requiring a rotating blade and related members. It is an object to provide a method and a wafer grinding apparatus for carrying out such a method.

In order to achieve the above-described object, according to a first invention, in a wafer grinding method for grinding a wafer including a chamfered portion located on the outer periphery and a flat portion located inward of the chamfered portion, The wafer is moved relative to the cup-type grinding wheel so that the chamfered portion of the wafer is positioned at a position corresponding to the cup-type grinding wheel, and the chamfering of the wafer is performed by the cup-type grinding wheel. The wafer is moved relative to the cup-type grinding wheel so that the flat portion of the wafer is positioned at a position corresponding to the cup-type grinding wheel. A wafer grinding method is provided for grinding the flat portion of the wafer.
According to a second invention, in the first invention, the wafer is bonded to a base substrate.
According to a third aspect, in the second aspect, the base substrate is another wafer having the same dimensions as the wafer.
According to a fourth aspect of the present invention, in a wafer grinding apparatus for grinding a wafer including a chamfered portion located on the outer periphery and a flat portion located inward of the chamfered portion, a cup-type grinding wheel for grinding the wafer And a moving mechanism for moving the wafer relative to the cup-type grinding wheel so that the chamfered portion or the flat portion of the wafer is positioned at a position corresponding to the cup-type grinding wheel. And the moving mechanism after positioning the chamfered portion of the wafer at a position corresponding to the cup-type grinding wheel and removing the chamfered portion of the wafer by the cup-type grinding wheel. The flat portion of the wafer is positioned at a position corresponding to the cup-type grinding wheel by the portion, and the flat portion of the wafer is ground by the cup-type grinding wheel. , Wafer grinding apparatus is provided.
According to a fifth aspect, in the fourth aspect, the wafer is bonded to a base substrate.
According to a sixth aspect, in the fifth aspect, the base substrate is another wafer having the same dimensions as the wafer.

In the first and fourth inventions, since the chamfered portion and the flat portion of the wafer can be positioned corresponding to the cup-type grinding wheel, the chamfered portion of the wafer is removed and flattened using a single cup-type grinding wheel. Both grinding and part grinding can be performed. Thus, the need for a rotating blade and its associated members can be eliminated.
In the second and fifth aspects, when removing the chamfered portion of the wafer, a part of the base substrate can be deleted together. For this reason, it is possible to avoid damage to the holding portion that holds the base substrate. The base substrate is preferably attached to the wafer with an adhesive or the like.
In the third and sixth inventions, a base substrate having the same dimensions as the wafer can be easily prepared.

1 is a schematic perspective view of a wafer grinding apparatus according to the present invention. It is a side view of the wafer grinding device based on this invention. FIG. 3 is a rear view of the wafer grinding apparatus shown in FIG. 2. FIG. 3 is a top view of the wafer grinding apparatus shown in FIG. 2. It is a figure which shows a wafer. (A) It is a fragmentary sectional view of a wafer grinding device when removing a chamfer. (B) It is a partial top view of the wafer grinding apparatus shown by Fig.6 (a). It is a partial side view of a wafer after chamfering part removal. (A) It is a fragmentary sectional view of a wafer grinding device when grinding a flat part. (B) It is a partial top view of the wafer grinding apparatus shown by Fig.8 (a). It is a partial side view of a wafer after flat part grinding.

Embodiments of the present invention will be described below with reference to the accompanying drawings. In the following drawings, the same members are denoted by the same reference numerals. In order to facilitate understanding, the scales of these drawings are appropriately changed.
FIG. 1 is a schematic perspective view of a wafer grinding apparatus according to the present invention. As shown in FIG. 1, the wafer grinding apparatus 10 mainly includes an arch-type column unit 12 having a cup-type grinding wheel 36 and a transfer unit 11 disposed below the column unit 12.

  The wafer grinding apparatus 10 grinds a wafer 60, for example, a silicon wafer. As shown in the drawing, a single groove 13 is formed in one side surface 12 b of the column unit 12 in the vertical direction, and this groove 13 extends from the top surface 12 a of the main unit 12 to the lower passage 14. Further, the transfer unit 11 can position such a wafer 60 at two desired positions corresponding to the cup-type grinding wheel 36. Further, the transport unit 11 carries the wafer 60 into and out of the grinding unit.

  As can be seen from FIG. 1, two linear guides 32 and 33 are provided on the side surface 12 b, respectively, on both edges of the groove 13 or adjacent to each other. Further, a similar linear guide 31 is provided in parallel to the columns 32 and 33 at the bottom of the groove 13. These columns 31, 32, 33 serve as guide rails that slide on a single saddle.

  2 is a side view of the wafer grinding apparatus according to the present invention, FIG. 3 is a front view of the wafer grinding apparatus shown in FIG. 2, and FIG. 4 is a top view of the wafer grinding apparatus shown in FIG. . As can be seen from these drawings, the transport unit 11 includes a transport base 21 on which two rails 22 parallel to each other are arranged. A chuck 29 for holding the wafer 60 is slidably disposed on the rail 22. The slider 25 coupled to the chuck 29 slides the ball screw 23 by a motor 26 via a belt / pulley mechanism 24. Thereby, the slider 25 comes to slide on the rail 22.

  The chuck 29 is connected to a vacuum source (not shown) and holds the wafer 60 by suction or the like. Further, a motor 27 is disposed below the transfer table 21, and the chuck 29 rotates around the vertical axis while holding the wafer 60.

  Further, as can be seen from FIGS. 2 and 3, a saddle 34 is slidably attached to the linear guides 32, 33 of the main unit 12. The saddle 34 is also slidably attached to the linear guide 31 via a nut 39 of a ball screw 38. As shown in the figure, a cup type grinding wheel 36 is attached below the saddle 34, and the cup type grinding wheel 36 slides along the linear guides 31 to 33 integrally with the saddle 34. . The rotation axis of the cup-type grinding wheel 36 is arranged in parallel to the linear guides 31 to 33. When the motor 35 provided in the saddle 34 is driven, the cup-type grinding wheel 36 rotates around the rotation axis.

  As described above, the ball screw 38 is disposed between the saddle 34 and the linear guide 31. The ball screw 38 is driven by a motor 37 disposed above, and serves as a grinding feed section that additionally feeds the cup-type grinding wheel 36 toward the wafer 60 of the chuck 29. As can be seen from FIGS. 2 and 4, the edge of the cup-type grinding wheel 36 is located on or adjacent to the feeding direction in which the cup-type grinding wheel 36 is fed toward the wafer 60. .

  FIG. 5 is a view showing a wafer. As shown in FIG. 5, a plurality of circuit patterns C, for example, through electrodes are formed in a lattice pattern on the surface 61 of the wafer 60 in the previous step. As can be seen from FIG. 5, all the circuit patterns C are formed on the flat portion 67 of the wafer 60, and the outer peripheral portion of the wafer 60 positioned around the flat portion 67 is formed as a chamfered portion 68. Note that such a circuit pattern C is not formed on the back surface 62 of the wafer 60.

  In FIG. 5, the surface 21 of the wafer 60 is attached to the base substrate 70 with an adhesive or the like. It is assumed that such a wafer 60 is supplied to the wafer grinding apparatus 10 shown in FIG. 1 and the like so that the base substrate 70 is positioned below.

  As shown in FIG. 5, the base substrate 70 is a flat member having substantially the same shape as the wafer 60. It is preferable to use another wafer 60 as the base substrate 70. In such a case, the base substrate 70 can be easily prepared. However, the base substrate 70 having another shape may be used.

  6A is a partial cross-sectional view of the wafer grinding apparatus when the chamfered portion is removed, and FIG. 6B is a partial top view of the wafer grinding apparatus shown in FIG. 6A. The removal operation of the chamfered portion 68 by the wafer grinding apparatus 10 according to the present invention will be described below with reference to these drawings.

  First, the wafer 60 is placed on the chuck 29. After the chuck 29 holds the wafer 60 in vacuum, the motor 26 is driven. As a result, the chuck 29 slides along the rail 22 and the screw 23 together with the slider 25. The tip of the cup-type grinding wheel 36 is positioned at a position corresponding to the chamfered portion 68 of the wafer 60, as shown in FIGS. 6 (a) and 6 (b).

  Next, the motor 35 is driven to rotate the cup-type grinding wheel 36 around the rotation axis, and the motor 27 is driven to rotate the chuck 29 around the rotation axis. Further, the motor 37 is driven to feed the cup-type grinding wheel 36 toward the wafer 60 of the chuck 29. As a result, the tip of the cup-type grinding wheel 36 grinds only the chamfered portion 68 of the wafer 60.

  When the cup-type grinding wheel 36 is fed in an amount sufficient to remove the chamfered portion 68 of the wafer 60, the motor 37 is rotated in reverse to separate the cup-type grinding wheel 36 from the wafer 60. FIG. 7 is a partial side view of the wafer after the chamfered portion is removed. As shown in FIG. 7, the cup-type grinding wheel 36 removes the chamfered portion 68 of the wafer 60 and a portion of the base substrate 70 corresponding thereto. As can be seen from FIG. 7, the base substrate 70 serves to prevent the chuck 29 from being damaged when the chamfered portion 68 is removed. It is also possible to remove the chamfered portion 68 by removing the base substrate 70 and holding the wafer 60 directly on the chuck 29.

  FIG. 8A is a partial cross-sectional view of the wafer grinding apparatus when grinding a flat portion. FIG. 8B is a partial top view of the wafer grinding apparatus shown in FIG. Hereinafter, the grinding operation of the wafer 60 by the wafer grinding apparatus 10 according to the present invention will be described with reference to these drawings.

  When the removal of the chamfered portion 68 is completed, the motor 26 is driven while the wafer 60 and the base substrate 70 are held by the chuck 29. As a result, the chuck 29 slides along the rail 22 and the screw 23 together with the slider 25. The chuck 29 is positioned at a position where the tip of the cup-type grinding wheel 36 corresponds to the flat portion 67 of the wafer 60 as shown in FIGS. 8A and 8B.

  Next, the motor 35 is driven to rotate the cup-type grinding wheel 36 around the rotation axis, and the motor 27 is driven to rotate the chuck 29 around the rotation axis. Further, the motor 37 is driven to feed the cup-type grinding wheel 36 by a predetermined amount (smaller than the thickness of the wafer 60) toward the wafer 60 of the chuck 29. As a result, the flat portion 67 of the wafer 60 is ground by the tip of the cup-type grinding wheel 36.

  When the cup-type grinding wheel 36 is fed by an amount for grinding the wafer 60 to a predetermined thickness, the motor 37 is rotated in the reverse direction to separate the cup-type grinding wheel 36 from the wafer 60. FIG. 9 is a partial side view of the wafer after flat portion grinding. As shown in FIG. 9, when the thickness portion of the flat portion 67 is ground, the wafer 60 is thinned to a desired thickness. Thereafter, the holding of the chuck 29 is released, and the wafer 60 and the base substrate 70 are removed. Next, the wafer 60 is separated from the base substrate 70 using a predetermined jig (not shown) or the like. Thereby, the thinned wafer 60 can be obtained.

  As described above, in the present invention, the chamfered portion 68 and the flat portion 67 of the wafer 60 can be positioned corresponding to the cup-type grinding wheel 36 by sliding the slider 25 on the screw 23. Therefore, the cup-type grinding wheel 36 functions as both an edge trimming cutter for removing the chamfered portion 68 of the wafer 60 and a grinding member for grinding the back surface 62 of the wafer 60. For this reason, the present invention does not require a rotating blade and related members as in the prior art, and the entire apparatus can be downsized.

DESCRIPTION OF SYMBOLS 10 Wafer grinding device 11 Conveyance unit 12 Column unit 12a Top surface 12b Side surface 13 Groove 14 Lower channel | path 22 Rail 23 Screw (movement mechanism part)
24 Pulley mechanism 25 Slider (moving mechanism)
26 Motor 27 Motor 29 Chuck (holding part)
31-33 Linear guide 34 Saddle 35 Motor 36 Cup type grinding wheel 37 Motor 38 Ball screw 39 Nut 60 Wafer 61 Front surface 62 Rear surface 67 Flat portion 68 Chamfered portion

Claims (2)

While horizontally holding a wafer including a chamfered portion positioned on the outer periphery and a flat portion positioned inward of the chamfered portion , the wafer is rotated about a rotation axis penetrating the wafer in the vertical direction and horizontally a wafer grinding method of grinding a one direction by the wafer chuck capable of sliding while holding the wafer,
A base substrate is attached to the surface of the wafer on which the circuit pattern is formed,
The chamfered portion of the wafer held by the wafer chuck is a cup-type grinding wheel installed so as to be movable in the vertical direction, and the rotation axis that passes through the center of the cup-type grinding wheel in the vertical direction is the center. The wafer chuck and the base substrate are slid in one direction with respect to the cup grinding wheel so that the wafer chuck is positioned at a position corresponding to the rotating cup grinding wheel.
By the cup-shaped grinding wheel, removing a portion of the base substrate corresponding to the chamfered portion and said surface preparative portion of the wafer on the back surface of the wafer,
The wafer chuck causes the wafer and the base substrate to slide in one direction with respect to the cup-type grinding wheel so that the flat portion of the wafer is positioned at a position corresponding to the cup-type grinding wheel. ,
A wafer grinding method in which the flat portion of the wafer on the back surface of the wafer is ground by the cup-type grinding wheel.   The wafer grinding method according to claim 1, wherein the base substrate is another wafer having the same dimensions as the wafer.

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