JP2011228331A - Cutting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting apparatus that can control the depth of a groove formed on a workpiece with high precision without reducing a processing efficiency.SOLUTION: A cutting apparatus has imaging means for imaging the cross-sectional shape of a processing groove 9 formed on a dividing scheduled line L from the outer peripheral surface side of a workpiece W. A cut-in amount to a dividing scheduled line to be afterwards processed is controlled on the basis of a cut-in amount of a cutting blade 30 into the workpiece W which is obtained from the cross-sectional shape of the processing groove 9 imaged by the imaging means 8, thereby forming a processing groove having a desired depth with high precision. The depth of the processing groove can be recognized and the cut-in amount of the cutting blade can be readjusted before one dividing scheduled line L is processed to form the processing groove 9 and then the cutting blade 30 is positioned to a cutting start position for a subsequent dividing schedule line, so that the processing efficiency can be prevented from being reduced.

Description

  The present invention relates to a cutting apparatus capable of controlling a cutting amount of a cutting blade with respect to a workpiece.

  A semiconductor wafer in which a plurality of circuits such as ICs and LSIs are partitioned by streets and formed on the surface is divided into individual semiconductor chips by cutting (dicing) the streets vertically and horizontally and used for various electronic devices. In recent years, in order to reduce the weight and size of electronic devices, it has been required to form a semiconductor chip as extremely thin as 100 μm or less and 50 μm or less. The technology to be developed has been developed and put into practical use (see, for example, Patent Document 1).

  In this tip dicing, each semiconductor is formed by forming a cutting groove having a depth corresponding to the thickness of the semiconductor chip on the surface of the semiconductor wafer, and then grinding the back surface of the semiconductor wafer to expose the cutting groove from the back surface side. This is a technique of dividing into chips, and when forming a cutting groove on the surface, it is required to control the depth of the groove with high accuracy.

  Furthermore, in processing of a workpiece formed by bonding a plurality of different materials, it may be required to form a groove that reaches the boundary surface between the materials with high accuracy. In order to control the groove depth with high accuracy, a groove is formed on a dummy wafer held on a sub-table installed near the holding means for holding the workpiece, and the groove is imaged from the surface side of the workpiece. A technique for measuring the depth of the groove and controlling the depth of cut has also been put into practical use (see, for example, Patent Document 2).

JP 2000-021820 A JP 2005-136292 A

  With the technique described in Patent Document 2, the depth of the groove formed in the workpiece has been controlled with high precision. However, for high precision control, frequent cutting into a dummy wafer during processing is required. It was necessary to go through and image the groove. If the frequency of cutting into the dummy wafer is increased, there is a problem that the processing efficiency is lowered.

  The present invention has been made in view of these facts, and the main technical problem thereof is to control the depth of grooves formed on a workpiece with higher accuracy than before without lowering the machining efficiency. The object is to provide a cutting device.

  The present invention includes a holding unit that holds a workpiece with a division schedule line set on the surface, a cutting blade that cuts the workpiece held by the holding unit along the division division line, a spindle that rotates the cutting blade, and a cutting blade. The present invention relates to a cutting device having a cutting means having a moving part that moves in the thickness direction of the workpiece, and a control means that controls the amount of movement of the moving part to adjust the cutting amount of the cutting blade into the work, It has an imaging means for imaging the cross-sectional shape of the machining groove formed on the planned dividing line from the outer peripheral side surface side of the workpiece, and the control means is for the cutting blade to the workpiece obtained from the cross-sectional shape of the machining groove imaged by the imaging means. Based on the cut amount, the cut amount to the division planned line to be processed later is controlled.

  The cutting means has a cutting water nozzle for supplying cutting water to the cutting blade, and the imaging means is installed in a direction opposite to the direction in which the cutting water scatters with reference to the contact position between the workpiece and the cutting blade. It is desirable.

  The present invention is provided with an image pickup means for picking up an image of the cross-sectional shape of the machining groove formed in the planned dividing line from the outer peripheral side surface of the workpiece, and there is a factor that causes the cutting depth to become constant, such as wear of a cutting blade. However, since the depth of subsequent cutting can be controlled based on the depth of the machining groove actually formed on the workpiece, a machining groove having a desired depth can be formed with high accuracy. In addition, after processing a single division line to form a machining groove, it is necessary to recognize the depth of the machining groove until the cutting blade is positioned at the cutting start position of the subsequent division line. Since the amount of cut can be adjusted again, the processing efficiency is not reduced.

It is a perspective view which shows an example of a cutting apparatus. It is a perspective view which expands and shows the C section of FIG. It is a front view which shows the state which cuts a workpiece | work and forms a processing groove. It is a top view which shows the state which forms a process groove | channel along the division | segmentation planned line of a workpiece | work. It is a side view which shows the state in which a process groove | channel is formed sequentially in a workpiece | work. It is a side view which shows the state which forms a process groove | channel in a workpiece | work sequentially, adjusting the cutting depth of a cutting blade. It is a perspective view which shows another example of a cutting apparatus. It is a top view which shows the state which forms two process grooves along the division | segmentation planned line of a workpiece | work.

  A cutting apparatus 1 shown in FIG. 1 is an apparatus in which two cutting means 3 a and 3 b cut a workpiece (workpiece) held by a holding means 2. Note that there may be only one cutting means.

  The holding means 2 includes a holding table 20 that holds the workpiece, a rotation support portion 21 that rotates the holding table 20 around the Z direction that is the vertical direction, and a clamp portion 22 that fixes the workpiece from the outer peripheral side. ing. The holding table 20 has a suction portion 200 that is formed of a porous member and holds a workpiece with a negative pressure.

  The holding means 2 is driven by the X-direction moving unit 4 and can move in the X direction orthogonal to the Y direction and the Z direction. The X-direction moving unit 4 includes a ball screw 40 having a rotation axis in the X-axis direction, a guide rail 41 arranged in parallel with the ball screw 40, a motor 42 connected to one end of the ball screw 40, and a lower portion. There is provided a moving base 43 which is in sliding contact with the guide rail 41 and in which a nut (not shown) is screwed into the ball screw 40, and the ball base 40 driven by the motor 42 is rotated to turn the moving base 43. The guide rail 41 is guided to move in the X direction.

  Since the two cutting means 3a and 3b are configured in the same manner, they will be described with common reference numerals. The cutting means 3 includes a cutting blade 30 that cuts the workpiece held by the holding means 2 and a spindle 31 that rotates the cutting blade 30 about a Y direction that is a direction orthogonal to the Z direction. Yes.

  The two cutting means 3a and 3b are respectively provided with Z direction moving parts 5a and 5b for moving the cutting blade 30 in the workpiece thickness direction (Z direction). Since the two Z-direction moving units 5a and 5b are configured in the same manner, a description will be given with common reference numerals. The Z-direction moving parts 5a and 5b include a ball screw 50 having a vertical rotation axis, a guide rail 51 disposed in parallel to the ball screw 50, a pulse motor 52 connected to one end of the ball screw 50, A side base is slidably in contact with the guide rail 51, and an inside / outside nut (not shown) is provided with an up / down base 53 to be engaged with the ball screw 50, and the ball screw 50 driven by the pulse motor 52 is rotated to move up and down. The base 53 is guided by the guide rail 51 and moves in the Z direction, and the cutting blade 30 is moved up and down in the Z direction together with the lift base 53.

  The cutting means 3a and 3b are driven by two Y-direction moving parts 6a and 6b, respectively, and are movable in the Y direction. Since the two Y-direction moving units 6a and 6b are configured in the same manner, they will be described with common reference numerals. The Y-direction moving units 6a and 6b include a ball screw 60 having a rotation axis in the Y-axis direction, a guide rail 61 disposed in parallel to the ball screw 60, and a pulse motor 62 connected to one end of the ball screw 60. And a moving base 63 in which a nut (not shown) is screwed into the ball screw 60 while the side portion is in sliding contact with the guide rail 61, and the ball screw 60 driven by the pulse motor 62 is rotated. The moving base 63 is guided by the guide rail 61 and moves in the Y-axis direction to move the cutting means 3 in the Y direction.

  An imaging unit moving unit 7 and an imaging unit 8 that is driven by the imaging unit moving unit 7 and moves in the Y direction are disposed on the moving base 43 that constitutes the X direction moving unit 4. The imaging means moving unit 7 includes a ball screw 70 having a rotation axis in the Y direction, a guide rail 71 disposed in parallel to the ball screw 70, a pulse motor 72 connected to one end of the ball screw 70, and a bottom portion. A moving base 73 is provided that is in sliding contact with the guide rail 61 and in which a nut (not shown) is screwed into the ball screw 70. The moving base 73 is rotated by the rotation of the ball screw 70 driven by the pulse motor 72. Is guided by the guide rail 71 and moves in the Y-axis direction, and the image pickup means 8 fixed to the moving base 73 is moved in the Y direction. The imaging means 8 has an optical axis in the X direction, and can image the workpiece from the side surface side in the X direction.

  The operations of the X direction moving unit 4, the Z direction moving unit 5, the Y direction moving unit 6 and the imaging means moving unit 7 are controlled by a control unit 10 having a CPU, a memory and the like. Therefore, the position of the holding table 2 driven by the X direction moving unit 4 in the X direction, the cutting amount of the cutting blade 30 by the control of the Z direction moving unit 5, and the cutting blade 30 adjusted by the Y direction moving unit 6. The position in the Y direction and the Z direction, the position in the Y direction of the imaging unit 8, and the like can be controlled by the control unit 10.

  As shown in FIG. 2, the cutting blade 30 is fixed to the spindle 31 by nuts 32, and a pair of cutting water that supplies cutting water to the cutting blade 30 is provided on both sides in the Y direction of the cutting blade 30. A supply nozzle 33 is provided.

In the cutting apparatus configured as described above, the work W is sucked and held by the holding means 2 as shown in FIG. A tape T is attached to the back surface of the workpiece W. The type of workpiece W is not particularly limited. For example, semiconductor wafers such as silicon wafers and gallium arsenide, adhesive members such as DAF (Die Attach Film) provided on the back surface of the wafer for chip mounting, semiconductor product packages, ceramics Glass, sapphire (Al ₂ O ₃ ) -based inorganic material substrates, various electronic components such as LCD drivers, and various processing materials that require micron-order processing position accuracy.

  When the workpiece W is held by the holding means 2, either the Z-direction moving portion 5a or the Z-direction moving portion 5b shown in FIG. 1 lowers the cutting means 3a or 3b, so that the lower end of the cutting blade 3 is predetermined. Is positioned in the Z direction position. Then, when the holding means 2 holding the workpiece W moves in the A direction which is the X direction, the workpiece W and the cutting blade 30 are cut and fed relatively in the X direction, and the cutting blade 3 which rotates at high speed in the B direction. Is cut into the workpiece W to form a groove 9 having a predetermined depth shown in FIG. During such cutting, the imaging unit 8 also moves in the A direction in conjunction with the holding unit 2. The depth of the groove 9, that is, the cutting amount of the cutting blade 30 with respect to the workpiece W can be adjusted by the Z-direction moving parts 5a and 5b shown in FIG.

  As shown in FIG. 3, at the time of cutting, cutting water 33a is ejected from the cutting water supply nozzle 33, and the cutting water 33a becomes mist 33b by the high-speed rotation of the cutting blade 30 in the B direction, along with cutting waste in the B direction. However, since the imaging unit 8 is installed in a direction opposite to the direction in which the mist 33b scatters with respect to the contact position between the workpiece W and the cutting blade 30, the mist 33b and cutting waste are present in the imaging unit 8. It can avoid sticking.

  As shown in FIG. 4, a plurality of lines L are cut and processed for a wafer W on which a device D is formed by being divided by a plurality of division lines L (hereinafter referred to as “lines L”) set on the surface. When forming a plurality of grooves, after forming the machining groove 9 in one line L1 by the relative movement of the cutting blade 30 and the workpiece W in the X direction, the cutting means 3a or 3b is raised and retracted. In this state, the cutting means 3a or 3b and the workpiece W move relative to each other in the direction opposite to that during cutting, thereby returning to the original positional relationship. Then, after the cutting blade 30 is indexed in the Y direction by the Y direction moving portion 6a or 6b shown in FIG. 1 and the next line L2 is aligned in the Y direction, the cutting means 3 is moved again. A machining groove is formed in the next line L2 by the relative movement of the cutting blade 30 and the workpiece W in the X direction. By repeating this, processed grooves are formed in all the lines L in the same direction. Further, by performing the same cutting after rotating the workpiece W by 90 degrees, machining grooves are formed in all the lines L vertically and horizontally.

  With the cutting depth adjusted by the control means 10, the cutting blade 30 is sequentially cut into the plurality of lines L, and as shown in FIG. 5, the machining grooves 9 having a desired depth Z1 are sequentially formed. Due to an error or the like, the depth of the formed processing groove is not necessarily a desired depth. Further, when wear occurs at the cutting edge of the cutting blade 30, the depth of the formed processing groove becomes shallower than the planned depth.

  Therefore, after the cutting of the one line L1 shown in FIG. 4 and the formation of the machining groove 9 in the line L1, the cutting blade 30 is positioned at the cutting start position of the line L2 to be machined next. The cross-sectional shape of the machining groove 9 formed in the line L1 is imaged by the imaging means 8 from the outer peripheral side surface side of the workpiece W in the X direction. Then, the image information acquired by imaging is transferred to the control means 10 and stored in a storage element such as a memory. Since the imaging unit 8 is driven by the imaging unit moving unit 7 and can move in the Y direction, for example, the interval between adjacent lines L is stored in the control unit 10 in advance, and the imaging unit 8 moves in the Y direction for each interval. If the control means 10 controls the image pickup means moving section 7 so that the index is fed to each other, the formed processed grooves can be picked up sequentially.

  The control means 10 obtains the depth of the machining groove (cutting amount of the cutting blade 30) individually by image processing from the image information of the machining groove acquired for each line, or calculates the difference between the depths of adjacent machining grooves. The amount of wear of the cutting blade 30 in the Z direction is calculated. When the cutting blade 30 is worn and its radius gradually decreases, the cutting blade 30 is lowered by the amount corresponding to the amount of wear when the Z-direction moving parts 5a and 5b are driven. By increasing the depth, as shown in FIG. 6, control is performed so that the processed groove is formed at a desired depth Z1. The adjustment of the cutting depth of the cutting blade 30 can be performed between cutting one line and positioning the cutting blade 30 at the cutting start position of the next line, thereby reducing productivity. Can be prevented. As a matter of fact, after cutting one line and before cutting the next line, imaging and calculation of the depth of the machining groove and the control of the cutting depth based on the depth value may not be in time. However, it is only necessary that the depth of cut can be corrected at the time of cutting several lines in time for such processing. That is, it suffices if the amount of cut into a line to be machined later can be controlled based on the actual amount of cut into the workpiece obtained from the cross-sectional shape of the machining groove.

  Since the cutting apparatus 1 shown in FIG. 1 has two cutting means 3a and 3b, two lines are formed by one cutting feed by causing two cutting blades 30 to act on separate lines. Can be cut one by one. When only one image pickup means 8 is provided as in this embodiment, the depth of the machining groove formed by machining with one of the cutting blades is obtained, and the wear of both cutting blades is determined based on the depth. With the assumption that the amount will be the same, the position of both cutting blades in the Z direction can be adjusted. Further, both of the machining grooves formed by the two cutting blades are imaged by one imaging means 8, and the depth of the machining grooves formed by the individual cutting blades is obtained individually to determine the wear amount of each cutting blade. It is also possible to individually adjust the positions of the two cutting blades in the Z direction.

  The cutting apparatus 11 shown in FIG. 7 which is another embodiment of the present invention has two imaging means 8a and 8b and imaging means moving units 7a and 7b that move the imaging means 8a and 8b independently in the Y direction. And. The imaging means moving parts 7a and 7b are screwed into ball screws 70a and 70b having Y-direction rotation shafts, pulse motors 72a and 72b connected to the ball screws 70a and 70b, and ball screws 70a and 70b, respectively. Moving bases 73a and 73b are provided. Imaging means 8a and 8b are fixed to the movable bases 73a and 73b, respectively. The imaging means moving units 7a and 7b include a pair of guide rails 71 common to both. The imaging means moving sections 7a and 7b move the moving bases 73a and 73 in the Y direction by the pulse motors 72a and 72b rotating the ball screws 70a and 70b, respectively, and are thereby guided by the guide rail 71 and imaged. The means 80 and 81 are configured to move in the Y direction. The cutting device 11 is configured in the same manner as the cutting device 1 because the portions other than the imaging units 8a and 8b and the imaging unit moving units 7a and 7b are configured in the same manner as the cutting device 1 shown in FIG. The same reference numerals as those of the cutting device 1 are attached to the portions, and detailed description thereof is omitted.

  In the case of having two imaging means 8a and 8b as in the cutting device 11 of FIG. 7, the imaging means 8a and 8b individually provide two machining grooves formed by machining with the two cutting blades 30. Images can be taken and the depth of each machining groove can be measured. For example, as shown in FIG. 8, a line L1 at one end of the wafer W and a line L7 at the other end are first cut by one cutting feed in the X direction to form machining grooves 90 and 91, respectively. Then, until the two cutting blades 30 are positioned at the cutting start positions of the lines L2 and L6 to be processed next, the imaging unit 8a captures the cross-sectional shape of the processing groove 90 formed in the line L1 in the X direction of the workpiece W. The image pickup means 8b images the cross-sectional shape of the processing groove 91 formed in the line L7 from the outer peripheral side surface in the X direction of the workpiece W. Then, the two pieces of image information acquired by imaging are transferred to the control means 10 and stored in a storage element such as a memory.

  Since the imaging means 8a and 8b are driven by the imaging means moving units 7a and 7b and can move independently in the Y direction, for example, an interval between adjacent lines L is stored in the control means 10 in advance. If the control means 10 controls the image pickup means moving parts 7a and 7b so that the image pickup means 8a and 8b are indexed in the direction in which the image pickup means 8a and 8b approach each other, the formed processing grooves can be picked up sequentially two by two. it can. In addition, when two cutting blades 30 are first positioned at the center of the wafer W and two lines near the center are cut, and then the cutting is performed while index feeding in a direction in which the cutting blades are separated from each other, The image pickup means 8a and 8b may also feed the index in the direction away from each other in accordance with the movement. When one cutting blade is positioned at the end line of the wafer W and the other cutting blade is positioned at the center of the wafer W, the cutting blades are indexed in the same direction. In order to perform cutting, the imaging means 8a and 8b may also take an image of the machining groove while feeding the index in the same direction according to the movement.

  The control means 10 individually calculates the wear amount in the Z direction of the two cutting blades 30 from the image information of the machining groove acquired for each line. Then, the Z-direction moving parts 5a and 5b individually control the positions of the two cutting blades 30 in the Z direction according to the individual wear amounts so that the machining groove has a desired depth. Thus, by making it possible to individually control the positions of the two cutting blades 30 in the Z direction, even when the two cutting blades 30 individually form machining grooves having different depths, the cutting depth The thickness can be controlled with high accuracy. Note that the adjustment of the cutting depth of the cutting blade 30 is performed from the point of time of cutting one line until the cutting blade 30 is positioned at the cutting start position of the next line, from the viewpoint of preventing productivity reduction. It is desirable, however, that after cutting one line and before cutting the next line, it is not possible to capture and calculate the depth of the machining groove and to control the depth of cut based on the depth value. If there is, it is only necessary to correct the depth of cut when cutting several lines in time for such processing. That is, it suffices if the amount of cut into a line to be machined later can be controlled based on the actual amount of cut into the workpiece obtained from the cross-sectional shape of the machining groove.

  In the conventional method in which a groove is formed in a dummy wafer held on a sub-table near the holding means and the depth of the groove is measured, a positional error in the Z direction occurs between the two tables. In some cases, an error may occur in the depth of the groove to be formed. However, in the present invention, the cutting depth of the cutting blade 30 is determined by imaging the processing groove formed in the actual workpiece held by the holding means 2. By adjusting, there is no error caused by using two tables as in the prior art, and the depth of the machining groove can be controlled with high accuracy.

  In the two embodiments described above, the imaging means 8, 8a, 8b and the imaging means moving units 7, 7a, 7b are arranged on the moving base 43 that moves the holding means 2 in the X direction. The means 8, 8a, 8b and the imaging means moving units 7, 7a, 7b may be arranged at other positions. For example, when the imaging means 8, 8a, 8b are arranged on the moving base 63 that constitutes the Y-direction moving units 6a, 6b, the imaging means 8, 8a, 8b and the cutting means 3a, 3b are interlocked. If the cutting blade 30 and the imaging means 8, 8a, 8b are adjusted in advance so that the positions in the Y direction coincide with each other, the processing grooves can be sequentially imaged without the imaging means moving portions 7, 7a, 7b. Can do.

  The imaging means 8, 8a, 8b and the imaging means moving units 7, 7a, 7b are retracted so as not to interfere with the movement of the holding means 2 when not in use, and are moved to a position where they can be imaged only when necessary. It is good also as composition to do.

1: Cutting device 2: Holding means 20: Holding table 200: Suction part 21: Rotating support part 22: Clamping part 3a, 3b: Cutting means 30: Cutting blade 31: Spindle 32: Nut 33: Cutting water supply nozzle 33a : Cutting water 33b: Mist 4: X direction moving part 40: Ball screw 41: Guide rail 42: Motor 43: Moving base 5a, 5b: Z direction moving part 50: Ball screw 51: Guide rail 52: Pulse motor 53: Elevating bases 6a, 6b: Y-direction moving part 60: Ball screw 61: Guide rail 62: Pulse motor 63: Moving base 7, 7, a, 7b: Imaging means moving parts 70, 70a, 70b: Ball screw 71: Guide rail 72, 72a, 72b: pulse motor 73, 73a, 73b: moving base 8, 8a, 8b: shooting Means 9,90,91: processed groove 10: control means W: wafer L, L1~L7: dividing lines

Claims (2)

Holding means for holding the workpiece with the planned dividing line on the surface;
Cutting process comprising: a cutting blade that cuts the work held by the holding means along the division line, a spindle that rotates the cutting blade, and a moving unit that moves the cutting blade in the thickness direction of the work. Means,
Control means for controlling the amount of movement of the moving part to adjust the amount of cutting of the cutting blade into the workpiece;
A cutting device comprising:
Having imaging means for imaging the cross-sectional shape of the machining groove formed in the planned division line from the outer peripheral side surface of the workpiece;
The control means is a cutting device that controls a cutting amount into a division line to be processed later based on a cutting amount of the cutting blade into the workpiece acquired from a cross-sectional shape of the machining groove imaged by the imaging device. . The cutting means is
A cutting water nozzle for supplying cutting water to the cutting blade;
2. The cutting apparatus according to claim 1, wherein the imaging unit is installed in a direction opposite to a direction in which the cutting water scatters with reference to a contact position between the workpiece and the cutting blade.

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