JP2012024895A - Cutting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting method for accurately detecting the state of a cutting blade.SOLUTION: This cutting method for cutting a workpiece with a cutting blade includes a cutting step of positioning the cutting blade to a cutting starting position and making it cut the workpiece, and relatively processing and feeding the cutting blade and the workpiece to cut the workpiece in one direction, a cutting blade return step of, after the execution of the cutting step, positioning the cutting blade to an evacuation position where the workpiece is not cut, relatively moving the cutting blade and the workpiece, in the opposite direction to the one direction, and further positioning the cutting blade to the cutting starting position, and a blade detecting step of detecting the state of the cutting blade with a blade detecting means having a light emitting section and light receiving section arranged on both sides of the outer rim of the cutting blade during the execution of the cutting blade return step.

Description

  The present invention relates to a cutting method for cutting a workpiece such as a wafer with a cutting blade.

  For example, in a semiconductor device manufacturing process, a plurality of circuit elements such as ICs and LSIs are formed on the surface of a wafer. The wafer on which the circuit elements are formed is ground on the back surface to be thinned to a predetermined thickness, and then cut with a cutting device to manufacture individual semiconductor chips.

  For example, as disclosed in Japanese Patent Application Laid-Open No. 7-276183, the cutting device is used to cut a workpiece, for example, a cutting blade having a thickness of about 30 μm, and the state of the cutting blade such as breakage (chip) or wear of the cutting blade. Blade detecting means for detecting Cutting is performed by rotating the cutting blade into the workpiece while rotating the cutting blade at a high speed of about 30000 rpm, and relatively moving the cutting blade and the workpiece.

  As the blade detection means, for example, as disclosed in JP-A-2-212045, an optical blade detection means having a light emitting portion and a light receiving portion arranged with a peripheral portion of the cutting blade interposed therebetween is widely used. It is used.

  On the other hand, when cutting a workpiece with a cutting device, while cooling the processing heat generated by the cutting and discharging the cutting waste generated by the cutting from the workpiece, while supplying cutting fluid to the cutting blade Cutting is performed.

JP 7-276183 A Japanese Patent Laid-Open No. 2-212045

  However, when the cutting fluid mixed with cutting waste is accompanied by the rotation of the cutting blade, the light received by the light receiving portion of the blade detecting means is hindered by the cutting waste, and there is a problem that accurate detection cannot be performed.

  The present invention has been made in view of these points, and an object of the present invention is to provide a cutting method capable of accurately detecting the state of the cutting blade.

  According to the present invention, there is provided a cutting method for cutting a workpiece with a cutting blade, wherein the cutting blade and the workpiece are relatively positioned while the cutting blade is positioned at a cutting start position and cut into the workpiece. A cutting step that feeds the workpiece and cuts the workpiece in one direction; and after performing the cutting step, the cutting blade and the workpiece are positioned at a retracted position where the cutting blade is not cut into the workpiece. And a cutting blade return step for positioning the cutting blade at the cutting start position, and at the time of execution of the cutting blade return step, the cutting blade is disposed with the outer periphery of the cutting blade interposed therebetween. There is provided a cutting method comprising: a blade detecting step of detecting a state of the cutting blade by a blade detecting means having a light emitting portion and a light receiving portion.

  Preferably, the cutting blade is covered with a blade cover including a top portion, a side wall, and a bottom wall having a slit from which a tip of the cutting blade acting as a processing point protrudes, and the blade detecting means The cutting step is disposed on the top and is performed while supplying cutting water to the cutting blade disposed in the blade cover.

  According to the cutting method of the present invention, since the state of the cutting blade is detected when the cutting blade return step is executed when the cutting blade is not cut into the workpiece, the detection of the cutting blade is not hindered by the cutting waste, and the cutting blade is Generated chipping or wear can be accurately detected.

It is a perspective view of a cutting device suitable for implementing the cutting method of the present invention. It is a side view of the cutting means cut in the blade cover part. It is sectional drawing explaining the cutting method of this invention. It is operation | movement explanatory drawing of a cutting step. It is operation | movement explanatory drawing of a return step. It is explanatory drawing which shows a cutting start position and a cutting end position.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a perspective view of a cutting device 2 suitable for carrying out the cutting method of the present invention. On the front side of the cutting device 2, there is provided operating means 4 for an operator to input instructions to the device such as machining conditions. In the upper part of the apparatus, there is provided a display means 6 such as a CRT for displaying a guidance screen for an operator and an image taken by an imaging means described later.

  Reference numeral 8 denotes a wafer cassette, and a plurality of semiconductor wafers (for example, 25 wafers) supported by an annular frame via a dicing tape are accommodated in the wafer cassette 8. The wafer cassette 8 is placed on a cassette elevator 9 that can move up and down.

  Behind the wafer cassette 8, a loading / unloading means 10 for unloading the wafer W before cutting from the wafer cassette 8 and loading the wafer after cutting into the wafer cassette 8 is disposed. Between the wafer cassette 8 and the loading / unloading means 10, a temporary placement area 12, which is an area on which a wafer to be carried in / out, is temporarily placed, is provided. Positioning means 14 for positioning at a certain position is provided.

  In the vicinity of the temporary placement area 12, transport means 16 having a turning arm that sucks and transports the frame F integrated with the wafer W is disposed, and the wafer W carried to the temporary placement area 12 is Adsorbed by the conveying means 16 and conveyed onto the chuck table 18 and sucked by the chuck table 18, and held on the chuck table 18 by fixing the frame F by a plurality of fixing means (clamps) 19. .

  The chuck table 18 is configured to be rotatable and reciprocally movable in the X-axis direction. Above the movement path of the chuck table 18 in the X-axis direction, an alignment unit 20 that detects a street to be cut of the wafer W is provided. It is arranged.

  The alignment unit 20 includes an imaging unit 22 that images the surface of the wafer W, and can detect a street to be cut by a process such as pattern matching based on an image acquired by imaging. The image acquired by the imaging unit 22 is displayed on the display unit 6.

  On the left side of the alignment means 20, a cutting means 24 for cutting the wafer W held on the chuck table 18 is disposed. The cutting means 24 is configured integrally with the alignment means 20, and both move together in the Y-axis direction and the Z-axis direction.

  As shown in FIG. 2, the cutting means 24 is mounted with a cutting blade 30 having a cutting edge (grinding stone portion) 30 a on a mount flange 28 fixed to the tip of a rotatable spindle 26, and is fixed by a fixing nut 32. It is configured. The cutting means 24 is configured to be movable in the Y-axis direction and the Z-axis direction, and the cutting blade 30 is located on an extension line of the imaging means 22 in the X-axis direction.

  The cutting blade 30 is entirely covered with a blade cover 34. The blade cover 34 includes a pair of side walls 34a and 34b, a bottom wall 34c, an upper wall (top part) 34d, and a pair of end walls (not shown).

  The side wall 34 b has a circular opening 36, and the spindle 26 is inserted into the circular opening 36. The bottom wall 34 c has a slit 38, and the cutting blade 30 a of the cutting blade 30 protrudes from the slit 38.

  An opening 35 is formed in the upper wall 34d of the blade cover 34, and the light emitting part 40 and the light receiving part 42 constituting the blade detecting means 44 are arranged through the opening 35 so as to sandwich the cutting edge 30a of the cutting blade 30. It is installed.

  As shown in FIG. 3, one end of the light emitting unit 40 is connected to an optical fiber 41 connected to a light emitting element (not shown), and one end of the light receiving unit 42 is also connected to an optical fiber connected to a photodetector.

  Depending on the amount of light detected by the photodetector connected to the light receiving unit 42, it is possible to detect chipping or wear generated on the cutting blade 30a of the cutting blade 30. The blade detection unit 44 includes an adjustment screw 58 that finely adjusts the positions of the light emitting unit 40 and the light receiving unit 42 with respect to the cutting blade 30a of the cutting blade 30, and a fixing screw 60 that fixes the adjusted position at the adjusted position.

  The blade cover 34 defines a space portion 43, and the cutting blade 30 is inserted into the space portion 43, except for the cutting blade 30 a of the cutting blade 30 that acts as a processing point protruding from the slit 38. Reference numeral 30 denotes a blade cover 34.

  The blade cover 34 has a cutting fluid supply path 46, one end of the cutting fluid supply path 46 is connected to a cutting fluid supply source 48, and the other end is supplied with cutting fluid into a space 43 in which the cutting blade 30 is inserted. A cutting fluid ejection port 50 is formed. The cutting fluid supply path 46, the cutting fluid supply source 48, and the cutting fluid outlet 50 constitute a cutting fluid supply means.

  Reference numeral 52 denotes a waste liquid collecting means. One end is connected to the end wall of the blade cover 34, and the cylinder 54 is attached to be inclined at a predetermined angle, and the suction source 56 is connected to the other end of the cylinder 54. Composed.

  The inclination angle of the cylindrical body 54 is preferably 30 degrees or less with respect to the holding surface of the chuck table 18. The smaller the inclination angle, the more stable continuous suction by the suction source 56 becomes possible. The waste liquid collecting means 52 is disposed on the side where the cutting liquid supplied to the cutting blade 30 scatters as the cutting blade 30 rotates.

  A cutting fluid discharge opening 43a is formed in the end wall of the blade cover 34, and the space 43 of the blade cover 34 and the inside of the cylindrical body 54 are preferably communicated with each other through the opening 43a. An opening 54 a that opens to the bottom is further formed at one end of the cylinder 54.

  A part of the cutting waste generated by the cutting is accompanied with the cutting fluid as the cutting blade 30 rotates, and a part of the cutting fluid containing the cutting waste is formed in the end wall of the blade cover 34 for discharging the cutting fluid. It is taken into the cylindrical body 54 of the waste liquid collecting means 52 through the portion 43a as indicated by an arrow D and is removed by suction by the operation of the suction source 56.

  The wafer W, which is a workpiece, is sucked and held on the chuck table 18 while being supported by the annular frame F via the dicing tape T as shown in FIG. Before starting the cutting, the wafer W held by the chuck table 18 is moved in the X-axis direction directly below the imaging unit 22, the wafer W is imaged by the imaging unit 22, and the street to be cut by the alignment unit 20 is detected. Perform alignment to detect.

  Based on this alignment, in a state where the street to be cut and the cutting blade 30 are aligned, the cutting blade 30 is cut into the wafer W while rotating in the direction of arrow A at a high speed of about 30000 rpm, By aligning and feeding the chuck table 18 in the direction of arrow B, the aligned street is cut. Arrow C is the processing direction.

  When the wafer W is cut by the cutting blade 30, the street of the wafer W is cut while the cutting liquid is ejected from the cutting liquid outlet 50 at the tip of the cutting liquid supply passage 46 toward the cutting edge 30a of the cutting blade 30. To do. In general, pure water is used as the cutting fluid.

  Next, with reference to FIG.4 and FIG.5, the cutting method of this invention is demonstrated in detail. FIG. 4 shows the operation of the cutting step. In the cutting step, while the cutting blade 30 is positioned at the cutting start position A and cut into the wafer W, the cutting blade 30 and the wafer W are relatively processed and fed to the cutting end position B in the direction of arrow C. To cut.

  After completion of the cutting step, a cutting blade returning step shown in FIG. 5 is performed. In the cutting blade returning step, the cutting blade 30 is moved up to a retracted position D where the cutting blade 30 is not cut into the wafer W, and the cutting blade 30 and the wafer W are relatively moved at the retracted position to return the cutting blade 30 in the direction of arrow E. Further, the cutting blade 30 is positioned at the processing start position A.

  In the cutting method according to the present embodiment, during the cutting blade return step, cutting is performed by the blade detection means 44 including the light emitting unit 40 and the light receiving unit 42 disposed with the outer peripheral edge (cutting blade) 30a of the cutting blade 30 interposed therebetween. Detects chipping or wear generated in the blade 30.

  Since the state of the cutting blade 30a of the cutting blade 30 is detected in a state where the cutting blade 30 is not cut into the wafer W, detection of chipping or wear of the cutting blade 30a of the cutting blade is not hindered by cutting waste, and the cutting blade The state of can be accurately detected.

  Next, the cutting start position and the cutting end position in the above-described cutting step will be described with reference to FIG. As shown in FIG. 6 (A), the cutting start position 62 and the cutting end position 64 may be set to change for each cutting line in the X-axis direction, or as shown in FIG. The cutting start position 62a and the cutting end position 64a may be fixedly set in the X-axis direction.

  Generally, when a circular workpiece such as a wafer W is cut, the cutting start position 62 and the cutting end position 64 are set to change in the X-axis direction as shown in FIG. To do. This is because such a setting enables cutting in a shorter time.

  In the embodiment of the cutting method described above, an example in which the wafer W is continuously cut from one end to the other end has been described. However, the cutting method of the present invention is not limited to this, and one point on the wafer W is selected. The present invention can be similarly applied to a chopper cut to be cut or a chopper traverse cut to cut an intermediate portion of the wafer W linearly.

2 Cutting device 18 Chuck table 24 Cutting means 30 Cutting blade 34 Blade cover 40 Light emitting part 42 Light receiving part 44 Blade detecting means 50 Cutting fluid ejection port 52 Waste liquid collecting means 62, 62a Cutting start position 64, 64a Cutting end position

Claims (2)

A cutting method of cutting a workpiece with a cutting blade,
A cutting step of cutting the workpiece in one direction by relatively cutting and feeding the cutting blade and the workpiece while positioning the cutting blade at the cutting start position and cutting the workpiece into the workpiece;
After performing the cutting step, the cutting blade is positioned at a retracted position where the cutting blade is not cut into the workpiece, the cutting blade and the workpiece are relatively moved in the opposite direction to the one direction, and the cutting blade is further moved. A cutting blade return step positioned at the cutting start position;
A blade detecting step of detecting a state of the cutting blade by a blade detecting means provided with a light emitting portion and a light receiving portion disposed across the outer peripheral edge of the cutting blade during the execution of the cutting blade returning step;
A cutting method characterized by comprising: The cutting blade is covered with a blade cover including a top portion, a side wall, and a bottom wall having a slit from which a tip of the cutting blade acting as a processing point protrudes;
The cutting method according to claim 1, wherein the cutting step is performed while supplying cutting water to the cutting blade disposed in the blade cover.

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