JP2010245254A - 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 includes: a step of holding the wafer W on a chuck table 4 having a holding surface for holding the wafer W and an axis 5 of rotation orthogonal to the holding surface; a step of positioning a first cutting blade 60 and a second cutting blade 66 on a line orthogonal to the axis 5 of rotation and at positions on both opposite sides with respect to and at an equal distance from the axis 5 of rotation; a first processing step of making the first cutting blade 60 cut in the wafer and rotating the chuck table 4 by 180&deg; to form a groove; and a second processing step of making the second cutting blade 66 cut in the wafer W while making the first cutting blade 60 cut in, and rotating the chuck table 4 by 360&deg;, wherein the second cutting blade 66 has a smaller abrasive grain size than the first cutting blade 60 and a larger blade thickness than the first cutting blade 60, and the rotating speed of the chuck table 4 in the first processing step is higher than that in the second processing 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 processing, cutting is possible at a feed rate of about 50 to 60 mm per second, but in circular processing where the chamfered portion of the outer periphery of the wafer is cut off, an 8-inch wafer is turned into an angle at a feed rate of 5 degrees per second. Cutting must be performed, and it takes about 72 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 a circular cutting process 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 the first cutting blade and the second cutting blade at equal distances on the opposite side, cutting the first cutting blade into the wafer to a predetermined depth, rotating the chuck table 180 degrees, and semi-circularly into the wafer A first machining step for forming a shape groove; and the second cutting blade is inserted into the semicircular groove at a predetermined depth while the first cutting blade is cut into a wafer. And a second machining step for rotating the chuck table at least 360 degrees, and the abrasive grain size of the second cutting blade is smaller than the abrasive grain size of the first cutting blade The blade thickness of the second cutting blade is larger than the blade thickness of the first cutting blade, and the rotation speed of the chuck table in the first processing step is compared with the rotation speed of the chuck table in the second processing step. And a high-speed wafer processing method.

  According to the present invention, rough cutting is performed with the first cutting blade with a thin blade thickness, and finish cutting is performed with the second cutting blade with a thick blade thickness. Therefore, in the first processing step with the first cutting blade, the rotation speed of the chuck table is set. The semi-circular groove formed in the first machining step is cut in the second machining step, so that the rotation speed of the chuck table can be increased to some extent and the productivity is improved. Can do.

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 a schematic side view explaining the cutting blade positioning step. FIG. 6 is a plan view of FIG. 5. It is a schematic side view explaining a 1st process step. FIG. 8 is a plan view of FIG. 7. It is a schematic side view explaining a 2nd process step. FIG. 10 is a plan view of FIG. 9.

  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 second cutting blade 66 has a blade thickness that is thicker than the blade thickness of the first cutting blade 60. For example, the first cutting blade 60 has a blade thickness of 200 to 300 μm, and the second cutting blade 66 has a blade thickness of 500 to 1000 μm.

  The first and second cutting blades 60 and 66 are both composed of, for example, an electroformed blade in which diamond abrasive grains are hardened by Ni plating. The average abrasive grain size of the second cutting blade 66 is the average abrasive diameter of the first cutting blade 60. It is smaller than the grain size.

  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. 6 is a plan view of FIG.

  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 wafer W is cut to a predetermined depth D1 as shown in FIG. 7 while rotating the first cutting blade 60 in step S12. As shown in FIG. 8, the first machining step is performed in which the chuck table 4 is rotated 180 degrees in the A direction to form the semicircular groove 68.

  Next, in step S13, the second cutting blade 66 is cut into the semicircular groove 68 to a predetermined depth D1 as shown in FIG. 9, and the chuck table 4 is at least 360 degrees in the A direction as shown in FIG. A second processing step for forming the circular groove 70 by rotating is performed.

  In the first processing step, since the cutting thickness of the first cutting blade 60 is relatively thin, for example, about 200 μm, and rough cutting, it is possible to perform circular cutting at an angle of 40 degrees per second, for example. Therefore, it takes 4.5 seconds for the 180 degree circular cutting. In this first machining step, the cutting surface of the semicircular groove 68 is somewhat rough because of rough cutting.

  In the second machining step, since the cutting thickness of the second cutting blade 66 is relatively thick, for example, 500 μm, and the average abrasive grain size of the blade is small, the cutting is performed at an angle of 10 degrees per second with an 8-inch wafer, for example. This is a relatively low-speed cutting process, and it takes 36 seconds to cut the entire circumference.

  Therefore, the time required for the first and second machining steps is 4.5 + 36 = 40.5 seconds. This is a reduction of about 30 seconds compared with 72 seconds required in the conventional method. By this second processing step, the annular region including the chamfered portion 7 of the wafer W is removed by cutting.

  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 processing method of the wafer W of the present embodiment, the rough cutting is performed by the first cutting blade 60 and the finish cutting is performed by the second cutting blade 66. Therefore, in the first processing step by the first cutting blade 60, the chuck table 4 The rotation speed of the chuck table 4 is increased to some extent because the first cutting blade 60 cuts along the cutting groove cut in the second machining step by the second cutting blade 66. And productivity can be improved.

  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 (1)

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;
Positioning the first cutting blade and the second cutting blade at an equal distance on the opposite side of the rotation axis on a straight line orthogonal to the rotation axis;
A first machining step of cutting the first cutting blade into a wafer to a predetermined depth and rotating the chuck table 180 degrees to form a semicircular groove in the wafer;
A second processing step of cutting the second cutting blade into the semicircular groove to a predetermined depth while cutting the first cutting blade into the wafer, and rotating the chuck table at least 360 degrees;
The abrasive grain size of the second cutting blade is smaller than the abrasive grain size of the first cutting blade,
The blade thickness of the second cutting blade is greater than the blade thickness of the first cutting blade,
The wafer processing method, wherein a rotation speed of the chuck table in the first processing step is higher than a rotation speed of the chuck table in the second processing step.

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