JP2015046551A - Cutting blade and wafer dividing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a starting point for generating cracks at a groove bottom of a cutting blade, and divide a wafer at a proper position along a formation position of the starting point.SOLUTION: A cutting blade (38) has an annular-shaped cutting blade (48) for cutting a wafer (W). A cross sectional shape on a tip side of the cutting blade is formed into a single blade shape by one face (48a) parallel to a face orthogonal to a rotation center shaft (C) and the other face (48b) directed to a direction inclined to one face from a peak point (48c) that is a tip on one face. The cutting blade is cut to a middle in a thickness direction of the wafer from a wafer surface side. Therefore, after a step of forming a cutting groove (M) inclined to the wafer surface by the groove bottom (Ma), an external force is given to the wafer to generate cracks (K) with a peak point (Mb) on a wafer rear face side at the groove bottom to divide the wafer into individual chips.

Description

  The present invention relates to a cutting blade and a wafer dividing method for dividing a wafer along a dividing line.

  A semiconductor wafer is divided on a line to be divided by a cutting apparatus having two rotating cutting blades by a dividing method called so-called step cut or dual cut (see, for example, Patent Document 1). Specifically, in step cutting, a half-cut groove whose bottom does not reach the back surface of the wafer is formed on the wafer surface with one cutting blade, and then the bottom side of the half-cut groove is cut with the other cutting blade. Thus, a cutting groove is formed. In the dual cut, two cutting blades cut simultaneously on different division planned lines of the wafer. In these dividing methods, a protective tape is first attached to the back side of the wafer, and then the cutting is performed with a cutting blade from the front side of the wafer to the middle in the thickness direction of the protective tape so that the wafer is completely cut in the thickness direction of the wafer. The Here, in the case of complete cutting, chipping (chips) may occur at the back side edge of the chip. Therefore, the chip is divided at a low cutting speed of the cutting blade so that the occurrence of chipping (chips) is acceptable.

  On the other hand, in cutting with a cutting blade, it is required to increase the processing speed without deteriorating the back surface processing quality. In order to meet these requirements, after forming a half-cut groove without completely cutting with a cutting blade, if external force is applied to the protective tape and cracks can grow and be divided starting from the half-cut groove, the cutting feed Speed can be increased significantly.

Japanese Patent Laid-Open No. 2003-334751

  However, in a normal cutting blade, the tip becomes semicircular due to wear, and the groove bottom of the half cut groove is also formed in a semicircular cross-sectional shape due to this influence. For this reason, when a crack is grown starting from the groove bottom of the half-cut groove, there is a problem that the formation position of the crack becomes non-uniform and it is difficult to divide the wafer at an appropriate position.

  The present invention has been made in view of the above problems, and its purpose is to form a starting point for generating a crack in the groove bottom of the cutting groove, and to divide the wafer at an appropriate position along the forming position of the starting point. It is to provide a cutting blade and a wafer dividing method that can be used.

  The cutting blade of the present invention is a cutting blade having an annular cutting blade for cutting a wafer, and the tip side of the cutting blade is directed from the top to the other side with the tip of one surface as a vertex. And the cross-sectional shape is a single-edged shape.

  According to this configuration, since the cutting blade is formed in a single-edged shape, when a cutting groove that is a half cut is formed on the wafer surface, the groove bottom of the cutting groove is also formed in a cross-sectional shape inclined according to the single-edged shape. Can do. Thereby, at the groove bottom, cracks are likely to occur toward the wafer back surface starting from the pointed position cut at the apex of the cutting blade, and the wafer can be divided at an appropriate position.

  The wafer dividing method according to the present invention is a wafer dividing method for dividing a wafer having a predetermined dividing line formed on the surface thereof along the planned dividing line using the cutting blade, A sticking step of sticking a protective tape on the back surface of the wafer, and after carrying out the sticking step, the protective tape side is held on a chuck table, and the cutting blade is moved from the wafer surface side to the middle of the wafer thickness direction. Cutting along the line to be cut and forming a cutting groove on the wafer where the groove bottom is inclined with respect to the wafer surface, and forming the cutting groove after performing the cutting groove forming process A dividing step of applying an external force to the formed wafer to generate a crack starting from the apex of the groove bottom, and dividing the wafer into individual chips along the planned dividing line. Also by this method, the above-described actions and effects can be obtained.

  According to the present invention, it is possible to form a starting point for generating a crack in the groove bottom of the cutting groove, and to divide the wafer at an appropriate position along the forming position of the starting point.

It is a schematic perspective view of the cutting device which concerns on this Embodiment. It is a disassembled perspective view of the blade unit which concerns on this Embodiment. It is a partial front schematic diagram of said blade unit. It is a disassembled perspective view of the blade unit which concerns on a modification. It is explanatory drawing of the sticking process which concerns on this Embodiment. It is explanatory drawing of the cutting groove formation process which concerns on this Embodiment. It is explanatory drawing of the division | segmentation process which concerns on this Embodiment.

  Hereinafter, a wafer dividing method according to the present embodiment will be described with reference to the accompanying drawings. FIG. 1 is a schematic perspective view of a cutting apparatus according to the present embodiment.

  As shown in FIG. 1, a cutting apparatus 1 includes a base 2, a chuck table 3, a chuck table moving mechanism 4 provided on the base 2 for processing and feeding the chuck table 3 in the X-axis direction, and a chuck table. 3 and a cutting mechanism 5 that cuts the wafer W held by 3.

  Here, the wafer W to be cut will be described. The surface of the wafer W having a disk shape is partitioned into a plurality of regions by streets ST which are the planned division lines arranged in a lattice pattern. In addition, various devices D such as IC, LSI, LED and the like are formed. A protective tape T is attached to the back surface of the wafer W, and the wafer W is mounted on the annular frame F via the protective tape T.

  The chuck table 3 includes a θ table 10 that is fixed to the upper surface of an X-axis table 16 to be described later and that can rotate about the Z-axis, and a holding unit 11 that is provided on the θ table 10 and holds the wafer W by suction. doing. A holding surface 12 is formed of a porous ceramic material at the center of the upper surface of the holding unit 11, and the holding surface 12 is connected to a suction source (not shown) through a flow path in the holding unit 11. Clamp portions 13 are provided at four positions around the holding portion 11. Each clamp portion 13 is driven by an air actuator (not shown) to sandwich and fix the frame F around the wafer W (see FIG. 6A).

  The chuck table moving mechanism 4 includes a pair of guide rails 15 arranged on the upper surface of the base 2 and parallel to the X-axis direction, and a motor-driven X-axis table 16 slidably installed on the pair of guide rails 15. Have. The chuck table 3 is provided on the X-axis table 16. A nut portion (not shown) is formed on the lower surface side of the X-axis table 16, and a ball screw 17 is screwed to the nut portion. A drive motor 18 is connected to one end of the ball screw 17. The ball screw 17 is rotationally driven by the drive motor 18, and the chuck table 3 is moved along the guide rail 15 in the X-axis direction.

  The cutting mechanism 5 is movable in the Y-axis and Z-axis directions by a gate-shaped column 21 fixed on the base 2, a blade unit moving mechanism 22 provided on the column 21, and the blade unit moving mechanism 22. And a pair of blade units 23 supported by each other.

  The blade unit moving mechanism 22 includes a pair of guide rails 25 parallel to the Y-axis direction with respect to the front surface of the column portion 21, and a pair of motor-driven Y-axis tables 26 slidably installed on the pair of guide rails 25. have. The blade unit moving mechanism 22 includes a pair of guide rails 27 arranged in front of each Y-axis table 26 and parallel to the Z-axis direction, and a motor-driven Z-axis table slidably installed on each guide rail 27. 28. A blade unit 23 is provided below each Z-axis table 28.

  A nut portion (not shown) is formed on the back side of each Y-axis table 26, and a ball screw 30 is screwed to these nut portions. Further, nut portions (not shown) are formed on the back side of each Z-axis table 28, and a ball screw 31 is screwed to these nut portions. Drive motors 33 and 34 are connected to one end of a ball screw 30 for the Y-axis table 26 and a ball screw 31 for the Z-axis table 28, respectively. The ball screws 30 and 31 are rotationally driven by the drive motors 33 and 34, and the blade unit 23 is moved along the guide rails 25 and 27 in the Y-axis direction and the Z-axis direction.

  Next, the blade unit 23 will be described in detail with reference to FIGS. FIG. 2 is an exploded perspective view of the blade unit 23 according to the present embodiment. FIG. 3 is a schematic partial front view of the blade unit 23.

  As shown in FIG. 2, the blade unit 23 includes a spindle unit 37 and a cutting blade 38 that is detachably attached to one end side of the spindle unit 37. A motor (not shown) is connected to the other end side of the spindle unit 37, and the cutting blade 38 is rotated by driving this motor so that a cutting groove M (see FIG. 6B) can be formed in the wafer W. It has become.

  The spindle unit 37 includes a spindle shaft 40 that constitutes a rotation shaft, and a spindle housing 41 that supports the spindle shaft 40. A tip end portion of the spindle shaft 40 protrudes from the spindle housing 41, and a mount flange 42 for fixing the cutting blade 38 is attached via a screw 43.

  The mount flange 42 has a cylindrical boss portion 45 and a fixed flange 46 extending outward from the outer peripheral surface of the boss portion 45. The boss portion 45 is provided with a fitting hole 45a (see FIG. 3) into which the tip portion of the spindle shaft 40 is fitted.

  The cutting blade 38 is a hub blade, and includes a cutting blade 48 made of a grindstone that cuts the wafer W, and a hub base 49 that holds the cutting blade 48. A through hole 49 a into which the boss 45 is inserted is formed at the center of the hub base 49. When the hub base 49 is inserted into the boss portion 45, a substantially half portion of the boss portion 45 protrudes from the hub base 49. A screw portion 45b is formed on the outer peripheral surface of the substantially half portion of the boss portion 45. The cutting blade 38 is fixed to the mount flange 42 by tightening a ring-shaped fixing nut 50 to a screw portion 45 b protruding from the hub base 49.

  The cutting blade 48 is formed in an annular shape by bonding abrasive grains such as diamond with a bonding material, and the wafer W is cut by bringing the cutting blade 48 rotating via the spindle shaft 40 into contact with the wafer W. Processed. One surface 48 a which is the left surface in FIG. 3 of the cutting blade 48 is held by the hub base 49. Further, one surface 48a of the cutting blade 48 is formed in parallel with a surface (ZX plane) orthogonal to the rotation center axis C that is parallel to the Y axis. On the tip side of the cutting blade 48, a vertex 48c is formed by the one surface 48a and the other surface 48b. The other surface 48b of the cutting blade 48 forms a tapered surface directed in a direction inclined from the apex 48c to the one surface 48a. Therefore, the cross-sectional shape on the tip side of the cutting blade 48 is formed in a single-edged shape.

  In the blade unit 23, the cutting blade 38 is a hub blade. However, as shown in FIG. 4, a blade unit 56 having a cutting blade 55 as a washer blade may be employed. The cutting blade 55 includes a cutting blade 57 formed in an annular shape, and the shape on the tip side of the cutting blade 57 is formed in the same shape as the cutting blade 48 described above. In FIG. 4, in the spindle unit 37, a mount flange 59 for fixing the cutting blade 55 is attached to the tip portion of the spindle shaft 40 via a screw 60. The mount flange 59 has a cylindrical boss portion 62 and a fixed flange 63 that continues to the boss portion 62. A screw portion 62a is formed on the outer peripheral surface of the boss portion 62, and a fixing nut 65 is screwed to the screw 62a. The cutting blade 55 is inserted into the boss portion 62, the detachable flange 66 is further inserted into the boss portion 62, and the fixing nut 65 is fastened to the screw portion 62 a, whereby the cutting blade 57 is fixed from both sides by the fixing flange 63 and the detachable flange 66. It is sandwiched and attached to the spindle shaft 40.

  Next, the flow of the wafer W dividing method according to the present embodiment will be described with reference to FIGS. FIG. 5 is an explanatory diagram of the sticking process. 6A and 6B are explanatory diagrams of the cutting groove forming step, and FIG. 7 is an explanatory diagram of the dividing step.

  As shown in FIG. 5, a sticking process is first implemented. In the attaching step, first, the wafer W is arranged inside the annular frame F with the surface facing downward. Thereafter, the back surface (upper surface) of the wafer W and the upper surface of the frame F are bonded together by the protective tape T, and the wafer W is mounted on the frame F via the protective tape T.

  As shown in FIG. 6, after performing the sticking process, the cutting groove forming process is performed. In the cutting groove forming step, first, the wafer W mounted on the frame F via the protective tape T is turned upside down, the surface of the wafer W faces upward, and the protective tape T is positioned below the wafer W so that the chuck table 3 is conveyed. Then, the wafer W to which the protective tape T is stuck is placed on the holding surface 12 in a state where the wafer W is within the holding surface 12 of the chuck table 3 (see FIG. 6A). Thereafter, the holding surface 12 communicates with a suction source (not shown), and the wafer W mounted on the frame F via the protective tape T is sucked and held on the chuck table 3. In this state, on the outer periphery of the chuck table 3, the frame F is sandwiched and held by the four clamp portions 13.

  After completing such holding, the lattice-shaped streets ST on the wafer W held on the chuck table 3 are aligned in parallel with the X-axis direction and the Y-axis direction by the rotation of the θ table 10. Next, the cutting blades 48 of the pair of blade units 23 are positioned on the streets ST closest to both ends of the wafer W in the Y-axis direction by the movement of the Y-axis table 26. Next, the depth Dp of the cutting groove M with respect to the wafer W of the cutting blade 48 rotated by the movement of each Z-axis table 28 is adjusted (see FIG. 6B). The depth Dp is set such that the apex Mb on the back surface side of the wafer W at the groove bottom Ma leaves a predetermined thickness from the back surface of the wafer W so that the cutting groove M becomes a half-cut groove. After the position of the cutting blade 48 is adjusted by the Z-axis table 28, the X-axis table 16 is relatively moved with respect to the cutting blade 48 rotated at high speed, so that the cutting groove M having a depth Dp along the street ST of the wafer W. Is formed. Each time one cutting groove M is formed, the Y-axis table 26 is moved by the pitch interval of the street ST in the Y-axis direction, and the cutting groove M is formed in all the streets ST parallel to the X-axis. The table 10 is rotated 90 °. Then, among the grid-like streets ST, the streets ST in which the cutting grooves M are not formed are made parallel to the X axis. From this state, the cutting grooves M are formed in all the streets ST parallel to the X axis in the same manner as described above, and the cutting grooves M are formed in all the lattice-shaped streets ST.

  As shown in FIG. 7, after performing the cutting groove forming process, the dividing process is performed. In the dividing step, first, the wafer W mounted on the frame F is carried into a dividing device (not shown) via the protective tape T. In the dividing apparatus, the frame F is held by the clamp portion 71 on the annular table 70, and the upper end of the expansion drum 72 is positioned between the wafer W and the frame F. Then, when the frame F is lowered together with the annular table 70, the expansion drum 72 is raised relative to the annular table 70. As a result, the protective tape T is expanded in the radial direction, an external force that is pulled in the surface direction is applied to the wafer W on which the cutting groove M is formed, and stress is concentrated on the vertex Mb of the groove bottom Ma. And the crack K which reaches the back surface of the wafer W from the vertex Mb is generated, and the wafer W is divided into a plurality of chips along the street ST.

  As described above, according to the dividing method according to the present embodiment, the groove bottom Ma of the cutting groove M serving as a half-cut groove is inclined according to the single-edged shape of the cutting blade 48, so that an external force is applied to the wafer W. When stress is applied, stress concentrates on the vertex Mb of the groove bottom Ma, and a large shearing force can be generated at the vertex Mb. Thereby, in each cutting groove M, the starting point of the crack K is stably maintained at the apex Mb, and it is possible to prevent the positions where the cracks K are divided into a plurality of chips from being shifted in the width direction of the street ST and causing variations. In addition, the size can be appropriately maintained with high accuracy.

  In the present embodiment, the wafer W can be completely cut in the thickness direction without being cut into the middle in the thickness direction of the protective tape T. Thus, as compared with complete cutting using only the cutting blade, the cutting groove M is formed by half-cutting, so that the cutting feed rate can be increased, and as a result, the throughput of chip division can be improved. In addition, since the cutting blade 38 does not reach the back surface of the wafer W in the division of the wafer W, the occurrence of chipping at the edge on the back surface side of the chip can be reduced.

  Furthermore, since the cutting blade 48 has a single-edged shape in which only the other surface 48b is inclined with respect to the ZX plane, the manufacturing process is simplified by reducing the number of steps for forming a tapered surface compared to a so-called double-edged cutting blade. be able to. Moreover, by making the cutting blade 48 into a single-edged shape, the thickness of the cutting blade 48 is reduced compared to the double-edged shape, and even when the angle of the cutting edge is made an acute angle, the cutting edge 48 is prevented from being rounded over time. Can do. Thereby, even if the exchange cycle is lengthened, the cutting edge 48 can be kept in a state where stress is easily concentrated on the apex Mb of the groove bottom Ma for a long period of time, and this also better divides the wafer W at an appropriate position. can do.

  In addition, this invention is not limited to the said embodiment, It can change and implement variously. In the above-described embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited to this, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  For example, the dividing step is not limited to the method described in the above embodiment, and may be changed as long as an external force is applied to the wafer W and the crack K can be generated from the vertex Mb. As an example of another method, a suction groove is formed at a position immediately below the street ST on the holding surface 12 of the chuck table 3, and the suction tape is negatively deformed to deform the protective tape T so as to be recessed. K may be generated.

  Further, the number of blade units 23 may be integrated, and according to this, a part of the configuration of the blade unit moving mechanism 22 such as the Z-axis table 28 may be omitted.

  As described above, the present invention is useful for a cutting blade that forms a cutting groove by half-cutting, and a dividing method that divides the wafer in which the cutting groove is formed by the cutting blade by applying an external force.

DESCRIPTION OF SYMBOLS 1 Cutting device 3 Chuck table 38 Cutting blade 48 Cutting blade 48a One side 48b The other side 48c Vertex 55 Cutting blade 57 Cutting blade M Cutting groove Ma Groove bottom Mb Vertex ST Street (division plan line)
T Protective tape W Wafer

Claims (2)

A cutting blade having an annular cutting blade for cutting a wafer,
The cutting blade is characterized in that the tip end side of the cutting blade is inclined from the apex of one surface toward the other surface, and the cross-sectional shape is formed in a single-edged shape. A method for dividing a wafer, wherein the cutting blade according to claim 1 is used to divide a wafer having a division line formed on the surface along the division line.
An adhering step of adhering a protective tape to the back surface of the wafer;
After carrying out the adhering step, the protective tape side is held on the chuck table, the cutting blade is cut from the wafer surface side to the middle of the wafer thickness direction, and cut along the planned dividing line. Cutting groove forming step for forming a cutting groove inclined to the wafer surface on the wafer;
After performing the cutting groove forming step, an external force is applied to the wafer on which the cutting groove is formed to generate a crack starting from the apex of the groove bottom, and the chip is divided into individual chips along the division line. Splitting process,
A wafer dividing method comprising:

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