JP2010245167A - Processing method of wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a processing method of a wafer which cuts and removes a chamfered part of a wafer while frequency of replacement and correction of a cutting blade can be reduced. <P>SOLUTION: The processing method includes: a step for mounting the cutting blade 24 of a thickness, as large as or less than twice of a radial distance of a region to be removed, on a spindle 10; a step for corresponding and holding a center of the wafer 2 to a rotary shaft on a chuck table 20; a step for positioning a first side surface of the cutting blade 24 having a first and second side surfaces on one of two intersections of projection of an axis of the spindle 10 and a circular inner circumferential edge of the region to be removed; a step for making the cutting blade 24 cut into a wafer 2; a step for removing the region to be removed by rotating the chuck table 20 by 360 degrees; and a step for positioning the second side surface in the other one of the two intersections as positioning of the cutting blade 24 in the cutting step at a predetermined timing. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a wafer processing method in which a plurality of wafers are continuously processed to remove a desired annular region at the wafer periphery by rotating the wafer while cutting a cutting blade at the periphery of the wafer.

  Semiconductor wafers with multiple devices such as IC and LSI on the front surface, wafers such as sapphire, glass, etc. are ground to the specified thickness after the back surface is ground and then divided into individual chips. Widely used in various electrical equipment.

  In recent years, with the thinning and miniaturization of electrical equipment, wafers are required to be thinner and, for example, ground to 100 μm or less. Conventionally, a chamfering process has been applied to the outer periphery of a wafer in order to prevent cracking and dust generation during the manufacturing process. FIG. 1B shows a chamfered portion 4 formed on the outer periphery of the wafer 2.

  Therefore, when the wafer is thinly ground, a chamfered portion on the outer periphery is formed in a knife edge shape (eave shape). If the chamfered portion on the outer periphery of the wafer is formed in a knife edge shape, there arises a problem that the wafer is damaged due to chipping from the outer periphery.

  In order to solve this problem, Japanese Patent Laid-Open No. 2000-173961 proposes a method of grinding the back surface of the wafer after removing the chamfered portion on the outer periphery of the wafer in advance. According to this prior art, the chamfered portion is removed by cutting the peripheral edge of the wafer with a cutting blade and removing a desired annular region. Then, since the back surface of the wafer is ground, the chamfered portion is not formed in a knife edge shape.

  That is, in this prior art, as shown in FIG. 1 (A), a chamfered portion is formed by cutting into a circular inner peripheral edge 6a of a desired annular region (planned removal region) 6 of the wafer 2 with a cutting blade and rotating the wafer 2 once. The annular region 6 including 4 is removed.

  Further, when manufacturing an SOI substrate (Silicon on Insulator substrate), as a method for removing an unbonded portion, a method for removing a desired annular region on the outer peripheral portion of a wafer using a cutting blade is disclosed in Japanese Patent Laid-Open No. Hei 8-107092. It is disclosed in the publication.

  On the other hand, the cutting blade is formed by solidifying superabrasive grains such as diamond and CBN (Cubic Boron Nitride) with metal or resin, and wears as a workpiece such as a semiconductor wafer is cut.

JP 2000-173961 A JP-A-8-107092 JP 2001-54866 A

  However, when a plurality of wafers are subjected to a process of cutting and removing a desired annular region in the outer peripheral portion with a cutting blade, there is a problem that so-called uneven wear occurs in which the cutting blade is worn unevenly on the left and right.

  This will be described with reference to FIG. Referring to FIG. 2A, a schematic diagram when the cutting blade 14 cuts the periphery of the wafer 2 is shown. A spindle 10 that is rotationally driven by a motor (not shown) is rotatably accommodated in a spindle housing 9 of the cutting unit 8.

  A mount flange 12 is detachably attached to the tip of the spindle 10, and a cutting blade 14 is attached to the mount flange 12 and fixed by a fixing nut 16.

  When the cutting blade 14 is positioned on the peripheral edge of the wafer 2 as shown in FIG. 2A and subjected to a cutting process for removing the peripheral edge portion, a portion indicated by hatching 14a in FIG. As a result of the wear, uneven wear of the cutting blade 14 indicated by reference numeral 18 in FIG. 2B occurs.

  In this way, the cutting depth cannot be controlled with the cutting blade with uneven wear, and when the wafer is cut with the cutting blade with uneven wear, the tapered tip end portion 14b is broken.

  Therefore, it is necessary to replace the cutting blade in which uneven wear has occurred with a new cutting blade or to flatten the tip of the cutting blade using an electric discharge machining apparatus as disclosed in Patent Document 3.

  The present invention has been made in view of these points, and an object of the present invention is to provide a method for processing a chamfered portion on the outer periphery of a wafer that can reduce the replacement frequency and correction frequency of a cutting blade.

  According to the present invention, there is provided a wafer processing method for removing a region to be removed including a chamfered portion on the outer periphery of the wafer by rotating the wafer while cutting a cutting blade into a peripheral portion of the wafer having a chamfered portion on the outer periphery. A cutting blade mounting step of mounting a cutting blade having a thickness greater than 1 and less than 2 times the radial distance of the region to be removed on the tip of the spindle, a holding surface for holding the wafer, and the holding surface A wafer holding step for holding the wafer with the center of the wafer being coincident with the rotation axis, and a cutting blade having first and second side surfaces. A positioning scan that positions the first side at one of two intersections of the projection of the spindle axis and the circular inner peripheral edge of the area to be removed. And after performing the positioning step, a cutting step for cutting the wafer to a predetermined depth while rotating the cutting blade, and after performing the cutting step, rotating the chuck table by at least 360 degrees A removing step for removing the region to be removed, and a positioning changing step for positioning the cutting blade in the cutting step at a predetermined timing and positioning the second side surface of the cutting blade at the other of the two intersections. A method for processing a wafer is provided.

  Preferably, the predetermined timing is a timing after the wafer holding step, the positioning step, the cutting step, and the removing step are performed on a predetermined number of wafers.

  According to the present invention, one side of the cutting blade in the thickness direction is first cut into the wafer to cut a plurality of wafers, and then the other side of the cutting blade in the thickness direction is cut into the wafer. Therefore, the tip of the tapered cutting blade can be prevented from being broken, and the replacement frequency and correction frequency of the cutting blade can be reduced.

FIG. 1A is a schematic perspective view of a semiconductor wafer showing a region to be removed, and FIG. 1B is a front view of the semiconductor wafer showing an outer peripheral chamfer. FIG. 2A is a schematic view showing a state where the cutting blade is cutting the peripheral edge of the wafer, and FIG. 2B is a view showing uneven wear at the tip of the cutting blade. It is a flowchart of the processing method of the wafer of this invention embodiment. It is explanatory drawing of a wafer holding | maintenance step. It is a perspective view of the state which supported the wafer with the annular frame via the dicing tape. It is explanatory drawing of a positioning step. It is explanatory drawing of a cutting step. FIG. 8A is an explanatory diagram of the removal step, and FIG. 8B is a front view of the wafer held on the chuck table in a state where the planned removal area on the outer periphery of the wafer is removed. It is explanatory drawing of a positioning change step.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 3, a flowchart of a wafer processing method according to an embodiment of the present invention is shown. In the wafer processing method according to the embodiment of the present invention, first, a cutting blade mounting step is performed in step S10.

  That is, as shown in FIG. 6, the cutting blade 24 is attached to the mount flange 12 attached to the tip of the spindle 10 of the cutting unit 8 and fixed with the fixing nut 16. Here, the cutting blade 24 has a thickness that is greater than 1 and less than 2 times the radial distance of the region to be removed 6 shown in FIG.

  The radial distance of the region 6 to be removed is, for example, about 0.5 mm. In this case, the thickness of the cutting blade 24 is preferably greater than 0.5 mm and less than 1 mm. Next, a wafer holding step of holding the wafer rotatably with the chuck table in step S11 is performed.

  As shown in FIG. 4, the chuck table 20 has a holding surface 20a for holding the wafer, and a rotating shaft 22 orthogonal to the holding surface 20a and passing through the center of the holding surface 20a. In this wafer holding step, the back surface of the wafer 2 is sucked and held by the chuck table 20 with the center of the wafer 2 aligned with the rotation shaft 22.

  In FIG. 4, the wafer 2 is directly sucked and held by the chuck table 20. However, as shown in FIG. 5, the wafer 2 is supported by the annular frame F via the dicing tape T, and the wafer 2 is sucked by the dicing tape T. The annular frame F may be held and fixed by a conventionally known chuck table 20 clamp.

  As shown in FIG. 5, the first street S1 and the second street S2 are formed orthogonally on the surface of the wafer 2, and are partitioned by the first street S1 and the second street S2. A large number of devices T are formed on the wafer 2.

  Next, the process proceeds to step S12, and it is determined whether or not the area to be removed (annular area) 6 has been removed for a predetermined number of wafers 2. In the case of negative determination, the positioning step of step S13 is performed. In this positioning step, as shown in FIG. 6, the non-facing surface 24a with respect to the spindle 10 of the cutting blade 24 is positioned at the inner peripheral edge 6a of the planned removal area 6 shown in FIG.

  Expressing this positioning step more generally, the first side surface 24a or 24b of the cutting blade 24 having the first and second side surfaces is projected on the axis 10a of the spindle 10 and the circular inner peripheral edge 6a of the region 6 to be removed. It is positioned at one of the two intersections. FIG. 6 shows a state where the cutting blade 24 is positioned at the right intersection of the two intersections.

  After positioning the cutting blade 24 in this way, a cutting step is performed in which a part of the cutting blade 24 in the thickness direction is cut into the wafer to a predetermined depth while the cutting blade 24 is rotated in step S14. FIG. 7 shows a state in which this cutting step is performed.

  With the cutting blade 24 cut into the wafer 2 in this way, in step S15, the chuck table 20 is rotated 360 degrees or more as indicated by an arrow A in FIG. ) Perform an annular region removal step to remove 6.

  FIG. 8B shows a front view of the wafer 2 held on the chuck table 20 after the annular region removing step is performed. Reference numeral 26 denotes the outer peripheral surface of the wafer 2 after the annular region is removed.

  Steps S11 to S15 are repeated for a plurality of wafers 2. When the chamfered portions 4 of the predetermined number of wafers are removed by the cutting blade 24 in this way, uneven wear as shown in FIG.

  If the determination in step S12 is affirmative, that is, if a predetermined uneven wear has occurred in the cutting blade 24 by removing the region to be removed (annular region) 6 for the predetermined number of wafers 2, the process proceeds to step S16, and FIG. As shown by arrow B, a positioning change step is performed in which the facing surface 24b of the cutting blade 24 facing the spindle 10 is positioned at the inner peripheral edge 6a of the area 6 to be removed.

  That is, in this positioning change step S16, the positioning of the cutting blade 24 in the cutting step is carried out with respect to the second side surface 24b of the cutting blade 24, the projection of the axis of the spindle 10 and the circular inner peripheral edge 6a of the area 6 to be removed. Position it at the other of the intersections.

  In this manner, the positioning of the cutting blade 24 is changed as indicated by the arrow B in FIG. 9, and Steps S11, S16, and Steps S14 to S15 are performed on the second predetermined number of wafers.

  After removing the annular region (scheduled removal region) 6 on the outer periphery of the wafer, a protective tape is applied to the surface of the wafer 2, and then the surface side of the wafer 2 is sucked and held on the chuck table of the grinding device, and the back surface of the wafer is attached. Since the chamfered portion 4 remaining after grinding is removed, the chamfered portion is not formed in a knife edge shape.

  According to the wafer processing method of the embodiment of the present invention described above, one side in the thickness direction of the cutting blade 24 having a predetermined thickness is first cut into the wafer to remove the annular region of the predetermined number of wafers, and then the cutting blade The other side of the thickness direction of 24 is cut into the wafer to remove the annular region of the predetermined number of wafers, so that the tip of the tapered cutting blade can be prevented from being bent, and the cutting blade replacement frequency and correction The frequency can be reduced.

2 Semiconductor wafer 4 Chamfered portion 6 Planned removal area (annular area)
6a Circular inner peripheral edge 8 Cutting unit 10 Spindle 10a Spindle axis 20 Chuck table 24 Cutting blade 24a Non-opposing surface 24b Opposing surface

Claims (2)

A wafer processing method for removing a region to be removed including a chamfered portion on the outer periphery of a wafer by rotating the wafer while cutting a cutting blade into a peripheral portion of a wafer having a chamfered portion on the outer periphery,
A cutting blade mounting step of mounting a cutting blade having a thickness greater than 1 and less than 2 times the radial distance of the area to be removed on the tip of the spindle;
A wafer holding step for holding a wafer with a chuck table having a holding surface for holding the wafer and a rotation axis orthogonal to the holding surface and passing through the center of the holding surface, with the wafer center aligned with the rotation axis;
Positioning the first side of the cutting blade having first and second sides at one of two intersections of the projection of the spindle axis and the circular inner peripheral edge of the area to be removed;
After performing the positioning step, a cutting step for cutting the wafer to a predetermined depth while rotating the cutting blade;
A removal step of removing the region to be removed by rotating the chuck table at least 360 degrees after performing the cutting step;
A positioning change step of positioning the cutting blade in the cutting step at a predetermined timing, and positioning the second side surface of the cutting blade at the other of the two intersections;
A wafer processing method characterized by comprising:   2. The wafer processing method according to claim 1, wherein the predetermined timing is after the wafer holding step, the positioning step, the cutting step, and the removing step are performed on a predetermined number of wafers.

Images