JP2015085398A - Cutting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting apparatus capable of accurately measuring a use limit of a cutting blade. A chuck table for holding a plate-shaped workpiece, a cutting means for cutting the workpiece held on the chuck table with a cutting blade, and a work feed relative to the chuck table and the cutting means. A three-dimensional measuring means for measuring a workpiece in three dimensions in the X-axis direction, the Y-axis direction, and the Z-axis direction orthogonal to each other, and acquiring shape information. A workpiece cut by the cutting blade, comprising processing means for processing the information acquired by the three-dimensional measuring means to generate image information; and output means for outputting the image generated by the processing means. The cutting groove is measured by a third dimension measuring means, and the image information processed by the processing means includes cross-sectional shape information of the cutting groove. [Selection] Figure 9

Description

  The present invention relates to a cutting device for cutting a plate-like workpiece.

  A wafer such as a semiconductor wafer formed on the surface by dividing a plurality of devices such as IC, LSI, etc. by dividing lines is divided into individual devices by a cutting device, and the divided devices are various electronic devices such as mobile phones and personal computers. Widely used in equipment.

  The cutting apparatus includes a cutting blade having a cutting edge at the tip. When cutting a workpiece such as a wafer using the cutting blade, the cutting blade is worn as the cutting is continued, and the cutting edge of the cutting blade is cut. The shape of the blade is R-shaped and shortens in the radial direction. However, the cutting process can be continued while always maintaining the sharpness by the action of the self-generated blade generated when the cutting blade is worn.

  Further, the tip shape of the cutting blade is basically transferred as it is to the shape of the cutting groove. If it is important to maintain the shape of the cutting groove, check the shape of the cutting edge of the cutting blade as appropriate, and if the cutting edge shape changes beyond the allowable value, replace the cutting blade with a new cutting blade. Then, the work of adjusting the shape by dressing is performed (for example, see JP 2013-059833 A).

  A chamfered portion on an arc extending from the front surface to the back surface is formed on the outer peripheral edge of the wafer used for manufacturing the semiconductor device. Therefore, if the wafer is thinned by grinding the back surface of the wafer, the knife edge formed by the arc surface and the ground surface remains dangerous, and the outer peripheral edge is chipped and the quality of the device is lowered. End up.

  In view of this, a peripheral processing method for removing the arc-shaped chamfered portion of the wafer with a cutting blade before grinding the back surface of the wafer, so-called edge trimming processing, has been developed and used in device manufacturing processing (for example, Japanese Patent Application Laid-Open No. 2000-2000). -173961).

  In the edge trimming process, the vertical part of the side surface of the blade edge is cut into the device surface side of the wafer to form a side surface perpendicular to the edge portion of the device surface, so it is necessary to adjust so that the R shape does not reach the edge portion. Therefore, a flat dress having a flat tip is formed on a cutting blade that has been worn by performing a predetermined amount of cutting (see, for example, JP 2010-000588 A).

JP 2013-059833 A JP 2000-173961 A JP 2010-000588 A

  Conventionally, in order to quickly recognize that the tip shape of the cutting blade has changed, a cutting groove for observation is formed by cutting into a dummy workpiece other than the workpiece, and the dummy workpiece is observed from the side with a microscope. Check the tip shape or check the machining amount limit where the tip shape changes in advance. When the machining amount reaches the machining amount limit, the cutting blade can be used even if the tip shape does not change so much. We deal with such as exchanging.

  However, if the cutting blade is replaced when the processing amount reaches the processing amount limit before the tip shape changes, the cutting blade may be replaced even if the tip shape has not actually changed. Economy is generated.

  This invention is made | formed in view of such a point, The place made into the objective is providing the cutting device which can measure the processing amount limit or use limit of a cutting blade correctly.

  According to the present invention, a chuck table for holding a plate-like workpiece, a cutting means for cutting the workpiece held on the chuck table with a cutting blade, and processing relative to the chuck table and the cutting means A three-dimensional measuring means for measuring a workpiece in three dimensions in the X-axis direction, the Y-axis direction, and the Z-axis direction orthogonal to each other and obtaining shape information; A processing unit that processes the information acquired by the three-dimensional measurement unit to generate image information, and an output unit that outputs the image generated by the processing unit, and is cut by the cutting blade. A cutting device is provided in which a cutting groove of an object is measured by a third dimension measuring unit, and the image information processed by the processing unit includes cross-sectional shape information of the cutting groove.

  Preferably, the cutting device includes tolerance storage means for storing a change tolerance of the cross-sectional shape of the cutting groove, and cross-sectional shape information of the cutting groove obtained by measuring a workpiece by the three-dimensional measurement means. And determining means for comparing the allowable change value and determining a use limit of the cutting blade.

  Since the cutting device of the present invention processes the information acquired by the three-dimensional measuring means by the processing means to generate a three-dimensional image, the groove shape of the cutting groove can be confirmed in the cutting device, and a dummy work is separately provided. There is no need to process and observe with another observation device, and the groove shape can be accurately grasped, and there is an effect that unnecessary blade maintenance work such as dressing is unnecessary.

It is a perspective view of the cutting device concerning the embodiment of the present invention which provided a three-dimensional measuring means. 2A is an exploded perspective view of the three-dimensional measuring means, and FIG. 2B is a perspective view thereof. 3A is a longitudinal sectional view of the three-dimensional measuring means, and FIG. 3B is a schematic explanatory view of the interference objective lens unit. It is a graph which shows the relationship between the voltage applied to a piezoelectric element, and elongation. It is a figure which shows the XY coordinate in the Z-axis coordinate of the pixel of the image pick-up element part which caught the strong light produced | generated by the interference objective lens unit in Z1-Z3 position. FIG. 6A shows a captured image in the vicinity of the groove bottom of the cutting groove imaged by a three-dimensional measurement unit including the interference objective lens unit, and FIG. 6B shows a captured image of an intermediate portion of the groove. It is a block diagram of the processing means which processes the measured value measured by the three-dimensional measuring means. 8A is a partially sectional side view showing the edge trimming process of the wafer when the R shape of the cutting blade tip is small, and FIG. 8B is the edge trimming process of the wafer when the R shape of the cutting blade tip is large. FIG. It is a top view of the wafer in which the edge trimming process was implemented. FIG. 10A is a cross-sectional view of a cutting groove formed by a cutting blade whose cutting edge R shape is within the allowable value, and FIG. 10B is a cutting formed by a cutting blade whose cutting edge R shape is outside the allowable value. It is groove sectional drawing.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1, a perspective view of a cutting device 2 according to an embodiment of the present invention is shown. Reference numeral 4 denotes a base of the cutting apparatus 2, and a chuck table 6 is disposed on the base 4 so as to be rotatable and reciprocally movable in the X-axis direction by a processing feed mechanism (not shown).

  A plurality of clamps 7 and a water cover 8 are arranged around the chuck table 6. A bellows 10 is connected to the water cover 8 and the base 4 in order to protect the shaft of the processing feed mechanism.

  A gate-shaped column 12 is erected on the rear side of the base 4. A pair of guide rails 14 extending in the Y-axis direction are fixed to the column 12. A Y-axis moving block 16 is mounted on the column 12 so as to be movable in the Y-axis direction along the guide rail 14 by an index feed mechanism 20 including a ball screw 18 and a pulse motor (not shown).

  A pair of guide rails 22 extending in the Z-axis direction are fixed to the Y-axis moving block 16. On the Y-axis moving block 16, a Z-axis moving block 24 is mounted so as to be movable in the Z-axis direction by being guided by the guide rail 22 by a Z-axis moving mechanism 30 including a ball screw 24 and a pulse motor 28. .

  A cutting unit 32 is attached to the Z-axis moving block 24. A spindle housing (not shown) is rotatably accommodated in the spindle housing 34 of the cutting unit 32, and a cutting blade 36 is detachably attached to the tip of the spindle. A three-dimensional measuring unit (three-dimensional measuring means) 48 is attached to the spindle housing 34 of the cutting unit 32.

  A support block 40 shown in FIG. 2 is fixed to the spindle housing 34. The fitting portion 50 of the three-dimensional measurement unit 48 is fitted into the concave portion 42 of the support block 40, the ball screw 44 passes through the through hole 52 formed in the fitting portion 50, and the ball screw 44 is fitted into the fitting portion 50. Is screwed into the nut built in.

  In the housing 80 of the three-dimensional measurement unit 48, an interference objective lens unit 54, an image sensor unit (camera) 56, and a light irradiation unit 58 including a white LED are disposed. Further, as shown in FIG. 3A, a half mirror 82 is provided in the housing 80.

  When the pulse motor 46 is driven, the ball screw 44 rotates, and the three-dimensional measurement unit 48 is moved in the vertical direction via a nut screwed into the ball screw 44. Therefore, when it is desired to measure the machining area with the three-dimensional measurement unit 48, the pulse motor 46 is driven to position the three-dimensional measurement unit 48 at the measurement start position above the measurement area.

  Referring again to FIG. 3A, reference numeral 84 denotes a piezoelectric element whose length is displaced (elongated) in accordance with a variable voltage supplied from the power source 86, for example, as shown in FIG. Accordingly, the height position (Z coordinate) of the interference objective lens unit 54 changes according to the displacement amount of the piezoelectric element 84.

  Referring to FIG. 3B, a schematic diagram of the interference objective lens unit 54 is shown. The interference objective lens unit 54 includes an objective lens 88, a reference mirror 94 disposed on the glass plate 90, and a half mirror 92.

  A reference mirror 94 is disposed at a position symmetrical to the focal position of the objective lens 88 with respect to the half mirror 92. The interference objective lens unit 54 configured in this manner includes a Mirau type, a Michelson type, a linic type, and the like.

  White light emitted from the white light source 58 is reflected by the half mirror 82 and irradiated onto the surface of the workpiece through the interference objective lens unit 54. When the reflected light from the surface of the workpiece interferes with the light reflected from the reference mirror 94, both of them overlap at the position where the objective lens 88 is in focus to generate interference light (interference signal), and clear interference fringes are formed. Arise.

  Accordingly, the pulse motor 46 is driven to position the three-dimensional measurement unit 48 at the measurement start position above the workpiece, and the voltage applied to the piezoelectric element 84 is changed to image the workpiece surface through the interference objective lens unit 54. Imaging is performed by the element unit 56.

  As a result, as shown in FIG. 5, since the light strongly interferes at the position where the measurement object is focused, it can be detected as the dot 11. The height of the interference objective lens unit 54 is changed to Z1 to Z3 as shown in FIGS. 5A to 5C, and a plurality of images are picked up by the image pickup device portion 56. Z1 indicates the vicinity of the bottom of the cutting groove, Z2 indicates the middle, and Z3 indicates the interference light dot 11 near the surface.

  Referring to FIG. 6, an image (photograph) of a cutting groove captured by a three-dimensional measurement unit 48 including an interference objective lens unit 54 is shown. 6A roughly corresponds to FIG. 5A, and FIG. 6B roughly corresponds to FIG. 5B.

  As shown in FIG. 7, the XY coordinate storage unit 96 stores the X coordinate and Y coordinate of the pixel of the image sensor unit 56 that captured the interference light generated by the three-dimensional measurement unit 48. At the same time, the displacement amount of the piezoelectric element 84 is obtained from the graph shown in FIG. 4 corresponding to the X coordinate and Y coordinate of the pixel that captured the interference light, and the Z coordinate of the interference objective lens unit 54 is obtained from this displacement amount. This Z coordinate is stored in the Z coordinate storage unit 98.

  In the image information generation unit 100, three-dimensional image information is obtained by three-dimensionally assembling the XY coordinates of the pixels stored in the XY coordinate storage unit 96 and the Z coordinates at the time of pixel acquisition stored in the Z coordinate storage unit 98. Is generated.

  The calculation unit 102 calculates the measurement value of the measurement target of the workpiece based on the three-dimensional image information generated by the image information generation unit 100. Measurement targets include the width, depth, shape, position, processing angle, bottom surface processing roughness and meandering of the processing groove formed on the workpiece by the processing means (the cutting blade 36 in this embodiment), the processing groove, and the like. It includes any of the width, height, volume, and shape of debris deposited in the vicinity, and the width, depth, and shape of the chip at the edge of the processed groove.

  The reference measurement value storage unit 106 stores a reference value serving as a determination reference for the measurement value. This reference value is a measured value of the processing area of the workpiece that has been appropriately processed by the processing means. The reference measurement value storage unit 106 includes an allowable value storage unit 107 that stores a change allowable value of the cross-sectional shape of the cutting groove formed by the cutting blade 36.

  The calculation unit 102 generates a comparison data composed of the reference measurement value stored in the reference measurement value storage unit 106 and the measurement value of the machining area of the workpiece processed by the machining means. have.

  The determination unit 108 compares the reference measurement value stored in the reference measurement value storage unit 106 with the measurement value of the processing area of the workpiece processed by the processing unit calculated by the calculation unit 102, It is determined whether to stop the processing by the processing means or to change the processing conditions.

  The determination unit 108 further compares the measured value of the cutting groove formed in the workpiece by the cutting blade 36 calculated by the calculation unit 102 with the change allowable value stored in the allowable value storage unit 107, and performs cutting. The use limit of the blade 36 is determined.

  The processing condition setting unit 110 includes a processing condition storage unit 112, a proper image information storage unit 114, and a processing condition adjustment unit 116. When the determination unit 108 determines that the machining condition should be changed, the machining condition adjustment unit 116 adjusts the machining condition to an optimum value, and controls the machining condition to the optimum value via the control unit 64.

  On the other hand, if the measured value of the machining area of the workpiece is significantly different from the reference measurement value, and it is determined that optimum machining cannot be performed only by changing the machining conditions, the control means 64 stops machining by the machining means. Let

  In the present embodiment, the XY coordinate storage unit 96, the Z coordinate storage unit 98, the image information generation unit 100, the calculation unit 102, the reference measurement value storage unit 106, and the determination unit 108 constitute the processing unit 60 shown in FIG.

  Next, with reference to FIG. 8 thru | or FIG. 10, embodiment which performs the edge trimming process to the wafer 11 with the cutting device 2 of this embodiment, and determines the use limit of the cutting blade 36 is described. FIG. 8A shows a partial cross-sectional side view of the state in which the wafer 11 is edge trimmed with a cutting blade 36 having a small R shape at the tip.

  The wafer 11 is attached to a dicing tape T whose outer peripheral part is attached to the annular frame F. The wafer 11 is sucked and held by the chuck table 6 of the cutting device via the dicing tape T, and the annular frame F is clamped and fixed by the clamp 7.

  The cutting blade 36 is cut into the chamfer 11e on the outer peripheral edge of the wafer 11 while rotating the cutting blade 36 at a high speed (for example, 30000 rpm), and the chuck table 6 is slowly rotated at least one turn in the arrow A direction. Perform edge trimming. As a result, as shown in FIG. 9, a cutting groove 68 is formed on the outer peripheral edge of the wafer 11 by edge trimming.

  When the R shape at the tip of the cutting blade 36 is small, that is, when the cutting blade 36 is not so worn, the cutting groove 68 formed by the edge trimming is formed on the wafer 11 as shown in FIG. A side surface perpendicular to the edge portion of the surface (device surface) is formed.

  However, as shown in FIG. 8B, when the edge trimming process is performed on the wafer 11 using the cutting blade 36 whose tip R shape is outside the allowable value, as shown in FIG. A cutting groove 68a having an R shape at the edge portion is formed. This is because the tip shape of the cutting blade 36 is transferred to the cutting groove 68a.

  In FIG. 10B, R1 is a height tolerance stored in the tolerance storage unit 107, and R2 is a height at which R (curved surface) of the cutting groove 68a formed by the cutting blade 36 is started. . Therefore, in the present embodiment, the calculation value R2 is calculated by the calculation unit 102 from the three-dimensional image generated by the image information generation unit 100, and the allowable change values R1 and R2 stored in the allowable value storage unit 107 by the determination unit 108 And the use limit of the cutting blade 36 is determined. In this example, since the calculated value R2 is larger than the allowable change value R1, the determination unit 108 determines that the use limit of the cutting blade 36 has come.

  As shown in FIG. 10, the three-dimensional image and the measurement value processed by the processing unit 60 are displayed on a display monitor 62 as an output unit. Accordingly, the operator of the cutting apparatus 2 can immediately confirm the shape of the cutting groove 68 and thus the tip shape of the cutting blade 36 by observing the display monitor 62.

  When the determination unit 108 determines that the use limit of the cutting blade 36 has come, dressing is performed on the cutting blade 36 or the cutting blade 36 is replaced with a new cutting blade.

2 Cutting device 6 Chuck table 11 Wafer 11e Chamfering portion 32 Cutting unit 36 Cutting blade 48 Three-dimensional measuring unit 54 Interference objective lens unit 56 Image sensor unit (camera)
58 Light irradiation units 68, 68a Cutting groove 84 Piezoelectric element 88 Objective lens 92 Half mirror 94 Reference mirror 96 XY coordinate storage unit 98 Z coordinate storage unit 100 Image information generation unit 102 Calculation unit 107 Allowable value storage unit 108 Determination unit

Claims (4)

Chuck table for holding a plate-like workpiece, cutting means for cutting the workpiece held on the chuck table with a cutting blade, and processing feed means for processing and feeding relative to the chuck table and the cutting means A cutting device comprising:
Three-dimensional measuring means for measuring a workpiece in three dimensions in the X-axis direction, the Y-axis direction, and the Z-axis direction orthogonal to each other and acquiring shape information;
Processing means for processing the information acquired by the three-dimensional measuring means to generate image information;
Output means for outputting the image generated by the processing means,
The cutting groove of the workpiece cut by the cutting blade is measured by the three-dimensional measuring means,
The image information processed by the processing means includes cross-sectional shape information of the cutting groove. Tolerance storage means for storing a change tolerance of the cross-sectional shape of the cutting groove;
A determination means for comparing the cross-sectional shape information of the cutting groove obtained by measuring the workpiece with the three-dimensional measuring means and the change allowable value to determine the use limit of the cutting blade;
The cutting apparatus according to claim 1, further comprising: The workpiece is composed of a wafer having an arc-shaped chamfered portion formed on the outer peripheral edge from the front surface to the back surface,
The cutting device according to claim 1 or 2, wherein the cutting means cuts the chamfered portion of the wafer held by the chuck table along a circumferential direction.   The said cutting groove is a cutting device in any one of Claims 1-3 containing the edge part where the formed groove | channel and the workpiece surface cross, the side wall of a groove | channel, and a bottom part.

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