JP2010245253A - Method of processing wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of circularly processing a wafer, having improved productivity. <P>SOLUTION: The method of processing the wafer performs circular cutting processing on the wafer by making cutting blades cut in the wafer and rotating the wafer, and the method includes: a wafer holding step of holding the wafer on a chuck table having a holding surface for holding the wafer and an axis of rotation passing the center of the holding surface and orthogonal to the holding surface such that the center of the wafer is aligned with the axis of rotation; a positioning step of positioning two identical kind of cutting blades on a straight line orthogonal to the axis of rotation and at positions on both opposite sides with respect to and at an equal distance from the axis of rotation; a cutting-in step of making the two cutting blades cut in the wafer to a predetermined depth while rotating the two blades after implementing the positioning step; and a circular processing step of performing the circular cutting processing on the wafer by rotating the chuck table by at least 180&deg; after implementing the cutting-in step. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a wafer processing method for performing circular cutting on a wafer by rotating the wafer while cutting a cutting blade into 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 electronic devices.

  In recent years, with the reduction in thickness and size of electronic devices, wafers are required to be thinner, 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.

  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.

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

  By the way, the diameter of semiconductor wafers tends to increase to 8 inches and 12 inches in order to improve productivity, and along with this, processing apparatuses such as diffusion furnaces, CVT apparatuses, dicing apparatuses, etc. It has been adapted to larger diameters.

  On the other hand, a processing apparatus corresponding to a wafer having a small diameter of 4 inches, 5 inches or the like exists and is actually in operation. Since such small-diameter wafers are hardly manufactured at present because they are not profitable, large-diameter wafers such as 8-inch and 12-inch wafers are cut into small-diameter wafers when machining with small-diameter processing equipment. There is a demand for processing.

  For such a demand, a large diameter wafer is cut into a circular shape by a cutting device equipped with a cutting blade and converted into a small diameter wafer (see, for example, JP-A-11-54461).

JP 2000-173961 A JP-A-8-107092 Japanese Patent Laid-Open No. 11-54461

  However, when performing circular machining as described in these patent documents using a disk-shaped cutting blade, the machining load is very large compared to normal linear machining, so the machining speed is increased. There is a problem that productivity is very bad.

  For example, in semiconductor wafer linear machining, cutting can be performed at a feed rate of about 50 to 60 mm per second, but in circular machining where the chamfered portion on the outer periphery of the wafer is cut off, an 8-inch wafer is angled at a feed rate of 5 degrees per second. Cutting must be performed, and it takes about 70 seconds to perform the circular processing of one wafer.

  The present invention has been made in view of these points, and an object of the present invention is to provide a circular processing method of a wafer capable of improving productivity.

  According to the present invention, there is provided a wafer processing method in which a cutting blade is cut into a wafer and the wafer is rotated to perform circular cutting on the wafer, the holding surface for holding the wafer, and the orthogonal to the holding surface. A chuck table having a rotation axis passing through the center of the holding surface, a wafer holding step for holding the wafer with the wafer center aligned with the rotation axis, and a straight line perpendicular to the rotation axis from the rotation axis. Positioning step for positioning two identical cutting blades at equal distances on opposite sides, cutting step for cutting the wafer to a predetermined depth while rotating the two cutting blades after performing the positioning step, and the cutting step After performing the above, the chuck table is rotated at least 180 degrees to circularly cut the wafer. The wafer processing method characterized by comprising the engineering steps, is provided.

  The cutting blade of the same type is a cutting blade in which the thickness of the cutting blade, the abrasive grain size, the abrasive grain type, the abrasive grain content, and the bond material that hardens the abrasive grains are the same type.

  According to the present invention, since two circular cutting blades of the same type are used and the chuck table is rotated at least 180 degrees to perform circular cutting on the outer periphery of the wafer, the productivity of circular cutting is increased to twice that of the conventional one. Is possible.

1 is a perspective view of a cutting apparatus suitable for carrying out the wafer processing method of the present invention. It is a perspective view of the semiconductor wafer supported by the annular frame via the dicing tape. It is a flowchart of the processing method of the wafer which concerns on this invention embodiment. It is explanatory drawing of a wafer holding | maintenance step. It is explanatory drawing of the cutting blade positioning step. It is explanatory drawing of a cutting step. It is explanatory drawing of a circular process step.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1, there is shown a perspective view of a cutting device (dicing device) 2 suitable for carrying out the wafer processing method of the present invention.

  The cutting device 2 is a two-spindle type cutting device that sucks and holds a workpiece on the chuck table 4, and the chuck table 4 reciprocates in the cutting feed direction (X-axis direction) while indexing feed direction (Y-axis direction). And the work of the first cutting means 6 and the second cutting means 8 moving in the cutting feed direction (Z-axis direction).

  For example, when dicing the semiconductor wafer W, the semiconductor wafer W held on the annular frame F via the dicing tape T is placed on the chuck table 4 and sucked and held as shown in FIG.

  The chuck table 4 is movable in the X-axis direction by the cutting feed means 10, and a first alignment means 12 having a first camera (first imaging means) 13 formed integrally with the first cutting means 6. The wafer W sucked and held by the chuck table 4 by the second alignment means 14 having the second camera (second imaging means) 15 formed integrally with the second cutting means 8 is a region to be cut. After the street is detected and the street and the cutting blade are aligned in the Y-axis direction, cutting is performed.

  The cutting feed means 10 includes a pair of X-axis guide rails 16 disposed in the X-axis direction, an X-axis movement base 18 slidably supported by the X-axis guide rails 16, and an X-axis movement base 18. An X-axis ball screw 20 that is screwed into a nut portion (not shown) formed on the X-axis and an X-axis pulse motor 22 that rotationally drives the X-axis ball screw 20.

  The support base 24 for instructing the chuck table 4 to be rotatable is fixed to the X-axis moving base 18, and is driven by the X-axis pulse motor 22 to rotate the X-axis ball screw 20. It is moved in the X-axis direction.

  On the other hand, the first cutting means 12 and the second cutting means 14 are supported by the guide means 26 so as to be indexable in the Y-axis direction. The guide means 26 includes a vertical column 28 disposed in the Y-axis direction orthogonal to the X-axis so as not to prevent movement of the chuck table 4 and a pair of Y disposed in the Y-axis direction on the side surface of the vertical column 28. A shaft guide rail 30, a first ball screw 32 and a second ball screw 34 arranged in parallel with the Y axis guide rail 30, and a first Y axis pulse motor connected to the first ball screw 32. 36 and a second Y-axis pulse motor 38 connected to the second ball screw 34.

  The Y-axis guide rail 30 supports the first support member 40 and the second support member 42 so as to be slidable in the Y-axis direction, and is provided in the first support member 40 and the second support member 42. Nuts (not shown) are screwed into the first ball screw 32 and the second ball screw 34, respectively.

  Driven by the first Y-axis pulse motor 36 and the second Y-axis pulse motor 38 and the first ball screw 32 and the second ball screw 34 rotate, respectively, the first support member 40 and the second The support members 42 are independently moved in the Y-axis direction.

  The positions of the first support member 40 and the second support member 42 in the Y-axis direction are measured by the linear scale 44 and used for precise control of the Y-axis direction positions. Although it is possible to provide a linear scale separately for each support member, it is better to measure the positions of both the first support member 40 and the second support member 42 with a single linear scale 44. It is possible to precisely control the distance between.

  A first moving member 46 to which the first cutting means 6 is attached is attached to the first support member 40 so as to be slidable in the vertical direction (Z-axis direction). The first Z-axis pulse motor When 48 is driven, the first moving member 46 is moved in the Z-axis direction.

  Similarly, a second moving member 50 to which the second cutting means 8 is attached is attached to the second support member 42 so as to be slidable in the vertical direction (Z-axis direction). By driving the shaft pulse motor 52, the second moving member 50 is moved in the Z-axis direction.

  As shown in FIG. 5, the first cutting means 6 includes a spindle 58 rotatably accommodated in a spindle housing 56 and a first cutting blade 60 attached to the tip of the spindle 58. The spindle 58 is rotated at a high speed such as 30000 rpm by a motor (not shown).

  The second cutting means 8 includes a spindle 64 rotatably accommodated in a spindle housing 62 and a second cutting blade 66 attached to the tip of the spindle 64. The spindle 64 is rotated at a high speed such as 30000 rpm by a motor (not shown).

  The first cutting blade 60 and the second cutting blade 66 are the same type of cutting blade. That is, the first and second cutting blades 60 and 66 are cutting blades having the same type of blade thickness, abrasive grain size, abrasive grain type, abrasive grain content, and bond material that hardens the abrasive grains. The first and second cutting blades 60 and 66 have a thickness of 0.5 to 1 mm, for example.

  As shown in FIG. 2, on the surface of the wafer W to be processed, the first street S1 and the second street S2 are formed orthogonally, and the first street S1 and the second street S2 A large number of devices D are formed on the wafer W.

  The back surface of the wafer W is attached to a dicing tape T that is an adhesive tape, and the outer peripheral portion of the dicing tape T is attached to an annular frame F. As a result, the wafer W is supported by the annular frame F via the dicing tape T.

  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, a wafer holding step is first performed in step S10.

  As shown in FIG. 4, the chuck table 4 has a holding surface 4a for holding the wafer, and a rotating shaft 5 orthogonal to the holding surface 4a and passing through the center of the holding surface 4a. In this wafer holding step, the center of the wafer W is aligned with the rotation shaft 5 and the back surface of the wafer W is sucked and held by the chuck table 4. The wafer W has a chamfered portion 7 that is chamfered on the outer periphery thereof. In the wafer processing method of this embodiment, the annular region including the chamfered portion 7 is removed by cutting.

  In FIG. 4, the wafer W is shown to be directly sucked and held by the chuck table 4, but actually, as shown in FIG. 2, the wafer W is supported by the annular frame F via the dicing tape T, The wafer W is sucked and held by the chuck table 4 via the dicing tape T.

  If the wafer W is sucked and held by the chuck table 4, the process proceeds to step S11 to perform the positioning step. In this positioning step, as shown in FIG. 5, the first cutting blade 60 and the second cutting blade 66 are positioned at positions symmetrical to the rotation axis 5 on a straight line orthogonal to the rotation axis 5.

  In other words, the axis 58a of the spindle 58 of the first cutting means 6 and the axis 64a of the spindle 64 of the second cutting means 8 are aligned on a straight line perpendicular to the rotation axis 5 of the chuck table 4, and further The first cutting blade 60 and the second cutting blade 66 are positioned at the same distance R from the rotary shaft 5 on the opposite side of the rotary shaft 5.

  In FIG. 5, the positioning positions of the first and second cutting blades 60 and 66 are shown on the inner side in the radial direction from the chamfered portion 7 of the wafer W, but in this embodiment in which the chamfered portion 7 is cut and removed in an annular shape, This positioning position is about 0.5 to 1.0 mm radially inward from the outer periphery of the wafer W.

  After the first and second cutting blades 60 and 66 are positioned in this manner, the first and second cutting blades 60 and 66 are rotated in step S12 while the wafer W is moved to a predetermined depth D1 as shown in FIG. The cutting step for cutting is performed.

  Further, with the first and second cutting blades 60 and 66 being cut into the wafer W in this way, the chuck table 4 is rotated 180 degrees or more in the A direction as shown in FIG. A circular processing step is performed (step S13). By this circular machining step, the annular region including the chamfered portion 7 of the wafer W is cut and removed.

  After forming an annular groove of a predetermined depth on the outer periphery of the wafer, a protective tape is applied to the surface of the wafer 2, and then the front 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 ground. Since the remaining chamfered portion 7 is removed, the chamfered portion is not formed in a knife edge shape.

  According to the wafer W processing method of this embodiment, the first and second cutting blades 60 and 66 of the same type are positioned in the predetermined relationship described above, and the chuck table 4 is rotated 180 degrees to form a circular shape on the outer periphery of the wafer W. Thus, the productivity can be increased to twice that of the conventional method.

  When a large-diameter wafer is cut into a small diameter, the wafer W needs to be fully cut. Therefore, the wafer W is supported by an annular frame F via a dicing tape T as shown in FIG. The wafer W is fully cut while being shallowly cut into the dicing tape T by the first and second cutting blades 60 and 66.

4 chuck table 5 rotating shaft 6 first cutting means 8 second cutting means 60 first cutting blade 66 second cutting blade

Claims (2)

A wafer processing method in which a cutting blade is cut into a wafer and the wafer is rotated to perform circular cutting on the wafer,
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;
A positioning step of positioning two similar cutting blades at equal distances on the opposite side of the rotation axis on a straight line perpendicular to the rotation axis;
A cutting step for cutting the wafer to a predetermined depth while rotating the two cutting blades after performing the positioning step;
A circular processing step of performing circular cutting on the wafer by rotating the chuck table at least 180 degrees after performing the cutting step;
A wafer processing method characterized by comprising:   2. The wafer according to claim 1, wherein the same type of cutting blade is a cutting blade in which a thickness of the cutting blade, an abrasive grain size, an abrasive grain type, an abrasive grain content, and a bond material that hardens the abrasive grains are of the same type. Processing method.

Images