JP2008307646A - Cutting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting apparatus capable of controlling the depth of a cutting groove within a permissible value when cutting a wafer by a cutting means. <P>SOLUTION: In the cutting apparatus, a depth h of cutting groove K just after cutting which is formed on a wafer W by a cutting means is measured by a non-contact type groove depth measuring means 30 utilizing ultrasonic wave. If the depth of the cutting groove measured does not satisfy the permissible value, the cutting feed amount can be adjusted by operating a Z-axis feeding means, so that the depth h of the cutting groove K can controlled within the permissible value when cutting the wafer W by the cutting means. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cutting apparatus for cutting a wafer held on a chuck table by a cutting means.

  A wafer on which a device such as an IC or LSI is divided and formed on a surface by dividing lines is divided into individual devices by a dicing apparatus and used for electronic devices such as mobile phones and personal computers. Here, the wafer is arranged on the dicing frame via an adhesive tape, and the cutting blade is positioned on a predetermined division line formed on the surface, and the wafer is divided into individual devices at a cutting depth reaching the adhesive tape.

  Further, when there is a laminate such as metal on the planned dividing line, a cutting groove having a predetermined depth is formed by the first cutting blade for removing the laminate, and then the cutting groove is formed by the second cutting blade. In some cases, the wafer is completely cut to divide the wafer into individual devices (see, for example, Patent Document 1). Furthermore, there is a case where a cutting groove having a depth corresponding to the finished thickness of the device is formed, and then the back surface of the wafer is ground to expose the cutting groove on the back surface of the wafer to divide the wafer into individual devices. .

  As described above, in order to form a cutting groove having a predetermined depth on the division line formed on the surface of the wafer, it is necessary to confirm whether or not the depth of the cutting groove is an allowable value.

JP 2003-197564 A JP 2006-38744 A

  However, in order to check the depth of the groove, the wafer in which the cutting groove is formed must be taken out of the dicing device and transported to the inspection device, and cutting is performed even if the depth of the cutting groove deviates from the allowable value. There is a problem that the depth of the cutting groove cannot be corrected immediately at the stage.

  The present invention has been made in view of the above, and an object of the present invention is to provide a cutting apparatus capable of maintaining the depth of the cutting groove at an allowable value when the wafer is cut by the cutting means.

  In order to solve the above-described problems and achieve the object, a cutting apparatus according to the present invention includes a chuck table for holding a wafer, cutting means for cutting a wafer held by the chuck table, the chuck table, and the chuck table. An X-axis feed means that relatively feeds the cutting means in the X-axis direction, a Y-axis feed means that relatively feeds the chuck table and the cutting means in the Y-axis direction, the chuck table, A cutting device comprising a Z-axis feeding means for cutting and feeding the cutting means relative to the Z-axis direction, the cutting apparatus being disposed adjacent to the cutting means and formed on the wafer by cutting with the cutting means. A groove depth measuring means for measuring the depth of the cutting groove is provided.

  Further, the cutting device according to the present invention is the above invention, wherein the groove depth measuring means includes an ultrasonic oscillator, and a wave receiver that receives a reflected wave oscillated from the ultrasonic oscillator and reflected by the wafer. A cylindrical portion that partitions a space formed by the ultrasonic oscillating portion, the receiving portion, and the surface of the wafer, a water supply portion that supplies water to the cylindrical portion and fills the space with water, and the receiving portion. A depth calculation unit that calculates a time difference between reflected waves received by the wave unit and calculates a depth of the cutting groove.

  Further, the cutting device according to the present invention is the above-described invention, wherein when the depth of the cutting groove measured by the groove depth measuring means does not satisfy an allowable value, the Z-axis feeding means is operated to perform cutting. Control means for adjusting the feed amount is provided.

  Since the cutting device according to the present invention measures the depth of the cutting groove formed in the wafer by the cutting by the cutting means by the groove depth measuring means, the measured cutting groove depth does not satisfy the allowable value. In this case, it is possible to adjust the cutting feed amount by operating the Z-axis feeding means, and there is an effect that the depth of the cutting groove can be maintained at an allowable value when the wafer is cut by the cutting means.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS A cutting apparatus that is the best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is an external perspective view showing an example of a cutting apparatus according to an embodiment of the present invention, FIG. 2 is a perspective view showing an extracted configuration around the cutting means, and FIG. FIG. 4 is an enlarged perspective view showing a configuration around a cutting blade, and FIG. 4 is a schematic front view of FIG. 3. A cutting apparatus 10 according to the present embodiment is applied to a cutting apparatus that cuts a wafer W along a division line. As shown in FIG. 1, a chuck table 11, an imaging unit 12, and a cutting apparatus are schematically shown. Means 20, a groove depth measuring means 30, and a control means 40 are provided.

  The cutting means 20 is of a dual cut type in which two cutting blades are arranged opposite to each other in the Y-axis direction and can perform a cutting operation in parallel, and along the planned dividing line of the wafer W held on the chuck table 11, The first cutting blade 21 performs a half cut, and a second cutting blade (not shown) performs a full cut of a half-cut portion. Here, the first blade 21 side of the cutting means 20 has a spindle 22 on which the first cutting blade 21 is detachably mounted, and a drive (not shown) that rotatably supports and rotates the spindle 22. And a cylindrical housing 23 including a source. As shown in FIGS. 3 and 4, the first blade 21 for half-cutting of the cutting means 20 includes a flange 24 that sandwiches the first cutting blade 21 from both sides, and a first cutting blade. A side nozzle 25 that supplies cleaning water for cooling and cooling from both sides of the wheel 21 and a wheel cover 26 are provided. Of the cutting means 20, the second blade side for full cutting is similarly configured and includes a housing 27 and the like.

  The first cutting blade 21 and the second cutting blade are extremely thin cutting grindstones having a substantially ring shape. In the present embodiment, the first cutting blade 21 for half-cutting is thicker than the second cutting blade for full-cutting.

  As shown in FIG. 2, the imaging means 12 is provided on the side of the housing 23, and is a microscope equipped with a CCD camera or the like that images the surface of the wafer W held on the chuck table 11, and is cut. This is for alignment used for positioning the first cutting blade 21 with respect to the power division planned line.

  As shown in FIG. 2, the chuck table 11 that holds the wafer W that is integrated with the frame F via the holding tape T is connected to a driving source 13 and is rotatable. The drive source 13 is fixed to the moving base 14. Here, the cutting apparatus 10 includes an X-axis feed unit 50, a Z-axis feed unit 60, and a Y-axis feed unit 70 for performing a feed operation necessary for the cutting operation. FIG. 2 shows a configuration example of the feed mechanism for the first cutting blade 21, but the feed mechanism for the second cutting blade is also symmetrically configured similarly.

  The X-axis feeding means 50 is for processing and feeding the chuck table 11 relative to the first blade 21 of the cutting means 20 in the X-axis direction by moving the movable base 14 in the X-axis direction. It is. The X-axis feed means 50 includes a ball screw 51 disposed in the X-axis direction, a pulse motor 52 connected to one end of the ball screw 51, and a pair of guide rails 53 arranged in parallel with the ball screw 51. A nut (not shown) provided at the lower part of the moving base 14 is screwed to the ball screw 51. The ball screw 51 is driven and rotated by a pulse motor 52, and accordingly, the moving base 14 is guided by a guide rail 53 and moves in the X-axis direction.

  The Z-axis feed means 60 moves the first blade 21 of the cutting means 20 by moving the support portion 15 supporting the housing 23 of the first blade 21 relative to the wall portion 16 in the Z-axis direction. This is for controlling the amount of cut with respect to the wafer W by moving it up and down. The Z-axis feeding means 60 is arranged in parallel with the ball screw 61 arranged in the Z-axis direction on one surface of the wall portion 16, a pulse motor 62 that rotates the ball screw 61, and the ball screw 61. A nut (not shown) inside the support portion 15 is screwed into the ball screw 61. The support portion 15 is driven by the pulse motor 62 and is guided by the guide rail 63 as the ball screw 61 rotates to move up and down in the Z-axis direction, and the first cutting blade 21 supported by the support portion 15. Is also configured to move up and down in the Z-axis direction.

  The Y-axis feeding means 70 moves the wall portion 16 supporting the housing 23 of the first blade 21 via the support portion 15 in the Y-axis direction, thereby moving the first blade 21 of the cutting means 20 to the chuck table. 11 for indexing and feeding relative to the Y-axis direction. The Y-axis feed means 70 includes a ball screw 71 disposed in the Y-axis direction, a pulse motor 72 connected to one end of the ball screw 71, and a pair of guide rails 73 arranged in parallel with the ball screw 71. A nut (not shown) provided inside the moving base 17 formed integrally with the wall portion 16 is screwed to the ball screw 71. The ball screw 71 is rotated by being driven by a pulse motor 72, and accordingly, the moving base 17 is guided by the guide rail 73 and moves in the Y-axis direction.

  Here, the step cut operation of the wafer W by the cutting apparatus 10 of the present embodiment will be described. In the cutting apparatus 10 of the present embodiment, the first cutting blade 21 is already used in parallel with the half-cut operation for forming a cutting groove with a predetermined cutting amount from the surface of the wafer W along the division line. The wafer W is divided for each device D by full-cutting the half-cut cutting groove portion using a second cutting blade.

  First, the first cutting blade 21 of the cutting means 20 is cut while the first cutting blade 21 rotated at a high speed is cut into the wafer W on the chuck table 11 by a cutting feed by the Z-axis feeding means 60. As shown in FIG. 3, the chuck table 11 is half-cut by cutting the line to be divided on the wafer W by machining and feeding the chuck table 11 relative to the workpiece 21 in the X-axis direction by the X-axis feeding means 50. A cutting groove K is formed. Cutting the next division line in the same direction is performed by indexing and feeding the first cutting blade 21 relative to the chuck table 11 by the Y-axis feed means 70 in the Y-axis direction by the division line width. Repeat as well. Then, after forming cut grooves K that are half-cut for all the division lines in the same direction, the wafer W is rotated by 90 ° by the rotation of the chuck table 11 and all the division schedules newly arranged in the X-axis direction. By repeating the same cutting process with the first cutting blade 21 for the line, a half-cut cutting groove K is formed.

  In parallel with such a half-cut operation along the line to be divided by the first cutting blade 21, the second cutting blade rotated at a high speed is fed to the wafer W on the chuck table 11 by cutting feed by the Z-axis feeding means. Half-cut cutting on the wafer W is performed by feeding the chuck table 11 relative to the second cutting blade in the X-axis direction with the X-axis feeding means while cutting at a predetermined cutting depth. The groove K is cut and fully cut. The full cut of the next half-cut cutting groove K in the same direction is performed by relatively indexing and feeding the second cutting blade relative to the chuck table 11 by the Y-axis feeding means by the planned division line width in the Y-axis direction. Repeat in the same way. After all the half-cut cutting grooves K in the same direction are fully cut, the wafer W is rotated by 90 ° by the rotation of the chuck table 11, and the half-cut cutting grooves K are newly arranged in the X-axis direction. Is divided into individual devices D by repeating the same full-cutting process with the second cutting blade.

  Next, the groove depth measuring means 30 and the control means 40 will be described. The groove depth measuring means 30 is for measuring the depth h of the cutting groove K formed in the wafer W by half cutting by the first cutting blade 21 of the cutting means 20 immediately after cutting. As shown in FIG. 5, the groove depth measuring means 30 measures the depth h of the cutting groove K in a non-contact manner using ultrasonic waves, and oscillates ultrasonic waves by applying a pulse voltage. The ultrasonic oscillating unit 31, the wave receiving unit 32 that receives the reflected wave oscillated from the ultrasonic oscillating unit 31 and reflected by the wafer W, the ultrasonic oscillating unit 31, the wave receiving unit 32, and the surface of the wafer W A cylindrical portion 34 that partitions the formed space 33, a water supply portion 36 that supplies water 35 to the cylindrical portion 34 from a supply source (not shown) and fills the space 33 with the water 35, and the wave receiving portion 32 receives the water. A depth calculation unit 37 that calculates the time difference t of the reflected wave and calculates the depth h of the cutting groove K. Here, the ultrasonic oscillating unit 31 and the wave receiving unit 32 are diagonally opposed to the surface of the wafer W. Further, the cylindrical portion 34 including the ultrasonic oscillating portion 31 and the wave receiving portion 32 is adjacent to a position on the cutting groove K (division planned line) immediately after cutting by the first cutting blade 21, and the wafer W The wheel cover 26 is fixed in proximity to the surface of the wheel cover 26 in a non-contact state. Thereby, the detection part except the depth calculation part 37 of the groove depth measurement means 30 moves integrally with the wheel cover 26, and the positional relationship with the first cutting blade 21 is fixed.

Here, as shown in FIG. 5, the depth calculation unit 37 sets the incident angle of the ultrasonic wave oscillated from the ultrasonic oscillation unit 31 to the wafer W and the reflection angle of the reflected wave reflected by the wafer W as α, 35, the velocity of sound traveling through 35 is v, and the second reflected wave reflected from the groove bottom of the cutting groove K from the time when the wave receiving section 32 receives the first reflected wave reflected from the surface of the wafer W. When the time difference up to the time when 32 is received is t, the depth h of the cutting groove K is:
h = cosα · v · t / 2
Calculated by Note that a third reflected wave reflected on the back surface (bottom surface) of the wafer W may also be generated, but the time difference t is obtained by paying attention to only the first and second reflected waves generated with priority in time. The third reflected wave can be ignored.

  When measuring the depth h of the cutting groove K, the space 33 formed by the ultrasonic wave oscillating unit 31, the wave receiving unit 32, and the surface of the wafer W is always filled with water 35. Sound waves do not propagate in the air. Ultrasonic waves can be measured more accurately because they are less attenuated and better propagated in water than in air. In particular, if pure water is used as the water 35, the propagation property is improved. In addition, the depth h of the cutting groove K is measured at a position immediately after cutting by the first cutting blade 21 while using cutting water, and the space 33 to be measured is supplied from the water supply unit 36. Therefore, the depth h of the cutting groove K can be stably measured without being adversely affected by the cutting water used in the vicinity of the first cutting blade 21.

  The control means 40 is for feedback control of the pulse motor 62 of the Z-axis feed means 60 based on the measurement result of the depth h of the cutting groove K measured by the groove depth measurement means 30. This control means 40 constantly monitors whether or not the depth h measured by the groove depth measuring means 30 is within a predetermined allowable value range, and the depth h is within the allowable value range. If the depth h is not within the allowable range, the pulse motor 62 of the Z-axis feed means 60 is operated to make the depth h within the allowable range. The cut amount of the first cutting blade 21 with respect to the wafer W is adjusted so as to be accommodated.

  Thus, according to the present embodiment, the depth h of the cutting groove K immediately after cutting formed on the wafer W by the cutting (half cutting) by the first cutting blade 21 of the cutting means 20 is always the groove depth. When the depth h of the cutting groove K measured by the measuring means 30 does not satisfy the allowable value, the pulse motor 62 of the Z-axis feed means 60 is operated by the control means 40 and the depth of the cutting groove K is determined. Since the cutting feed amount of the first cutting blade 21 is adjusted so that h falls within the allowable range, the depth of the cutting groove K formed when the wafer W is half-cut by the first cutting blade 21. h can be maintained within a tolerance range. Therefore, the depth h of the cutting groove K formed by the half cut can be maintained within an allowable value, and the wafer W can be surely fully cut by the second cutting blade.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the present embodiment, the example in which the step cut is performed by the dual cut method in which the first cutting blade 21 for half cut and the second cutting blade for full cut are arranged to face each other in the Y-axis direction has been described. However, it has a biaxial structure that includes a first cutting blade for half-cutting and a second cutting blade for full-cutting back and forth in the X-axis direction. The same can be applied to a cutting apparatus of the type described in (1). In this case, the groove depth measuring means may be arranged on the division line between the first and second cutting blades.

  In the present embodiment, the groove depth measuring means 30 is disposed adjacent to the position immediately after the cutting of the first cutting blade 21, but the cutting groove K half-cut by the first cutting blade 21 is used. If the depth is measurable, it may be arranged at a position adjacent to the front side of the first cutting blade 21.

  In the present embodiment, the groove depth measuring means 30 using ultrasonic waves has been described as an example. However, the depth of the cutting groove is measured in a non-contact manner using light, particularly laser light. May be.

  In the present embodiment, the cutting groove formed when half-cutting the wafer W is targeted. However, the cutting groove is not limited to the half-cutting, but has a depth corresponding to the finished thickness of the device, for example. Can be similarly applied to a case where the wafer is divided into individual devices by grinding the back surface of the wafer to expose the cutting groove to the back surface of the wafer and dividing the wafer into individual devices. .

It is an appearance perspective view showing an example of a cutting device of an embodiment of the invention. It is a perspective view which extracts and shows the structure around the cutting means of FIG. It is a perspective view which expands and shows the structure around the 1st cutting blade. FIG. 4 is a schematic front view of FIG. 3. It is a schematic diagram which shows the structural example of a groove depth measurement means and a control means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Chuck table 20 Cutting means 21 1st cutting blade 30 Groove depth measurement means 31 Ultrasonic oscillation part 32 Wave receiving part 33 Space 34 Cylinder part 35 Water 36 Water supply part 40 Control means 50 X-axis feed means 60 Z-axis feed Means 70 Y-axis feed means

Claims (3)

A chuck table for holding a wafer, a cutting means for cutting a wafer held on the chuck table, an X-axis feed means for processing and feeding the chuck table and the cutting means relatively in the X-axis direction, and the chuck Cutting provided with Y-axis feeding means for indexing and feeding the table and the cutting means in the Y-axis direction, and Z-axis feeding means for relatively cutting and feeding the chuck table and the cutting means in the Z-axis direction A device,
A cutting apparatus, comprising: a groove depth measuring unit that is disposed adjacent to the cutting unit and measures a depth of a cutting groove formed in the wafer by cutting by the cutting unit. The groove depth measuring means includes:
An ultrasonic oscillator,
A wave receiving unit that receives a reflected wave oscillated from the ultrasonic wave oscillation unit and reflected by a wafer;
A cylindrical part that partitions a space formed by the ultrasonic wave oscillating part, the wave receiving part, and the surface of the wafer;
A water supply part for supplying water to the cylindrical part and filling the space with water;
A depth calculation unit for calculating a time difference between reflected waves received by the wave receiving unit and calculating a depth of the cutting groove;
The cutting apparatus according to claim 1, comprising:   When the depth of the cutting groove measured by the groove depth measuring means does not satisfy an allowable value, the cutting groove is provided with control means for adjusting the cutting feed amount by operating the Z-axis feeding means. The cutting device according to claim 1 or 2.

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