JP2007294585A - Method and device for cutting wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a device from being damaged by the occurrence of large chippings when dividing a wafer with an element for testing on a line to be separated, into individual devices. <P>SOLUTION: The line S to be separated of the wafer W is formed by allowing the line S to be separated with the element 10 for testing to divide a plurality of devices D. When the line S to be separated is divided into individual devices D; a cutting edge 820 is cut deeply for cutting the line S to be separated while the cutting edge 820 of a cutting blade 82 is positioned at a position in the line S to be separated, and prevents the center in the widthwise direction of the element 10 for testing from coinciding with the center in the widthwise direction of the cutting edge 820. The center in the widthwise direction of the cutting edge 820 does not wear in a recess, thus preventing large chippings for damaging the devices D from occurring. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for cutting a predetermined separation line formed on a wafer and dividing it into individual devices, and a cutting apparatus suitable for carrying out the method.

  A wafer in which a plurality of devices such as ICs and LSIs are divided by planned separation lines is divided into individual devices by cutting the planned separation lines vertically and horizontally using a cutting blade that rotates at high speed. At the time of cutting, a cutting blade is positioned at the central portion of the planned separation line, and the central portion of the planned separation line is cut (see, for example, Patent Document 1).

  Further, a type in which a plurality of test elements 10 for inspecting device characteristics called TEG (Test Element Group) are formed on the planned separation line S that partitions the device D as in the wafer W shown in FIG. Even when the wafer is divided, as shown in FIG. 16, the center portion of the planned separation line S including the test element 10 is cut using the cutting blade portion 820 of the cutting blade 82. By cutting in this way, a kerf G is formed at the center of the planned separation line S as shown in FIG. Then, all of the scheduled separation lines S are cut in the same manner to be divided into individual devices D.

Japanese Patent Laying-Open No. 2005-311033

  However, if the planned separation line S on which the test element 10 is formed is cut, a large chipping exceeding the width of the planned separation line S occurs, leading to the device D, causing a problem of damaging the device D. Such a problem is that the thickness of the cutting blade portion 820 of the cutting blade 82 is larger than the width of the test element 10, and as shown in FIG. 17, the portion in contact with the test element 10, that is, the center of the outer periphery of the cutting blade portion 820. If the part wears in a concave shape and the cutting by the worn cutting edge part 820 is continued, it is considered that the surface side and the back side of the cutting edge part 820 vibrate or chip.

  Therefore, the problem to be solved by the present invention is to prevent the chip from being damaged due to a large chipping when the wafer on which the test element is formed in the planned separation line is divided into individual devices. .

  A first invention uses a cutting apparatus including at least a chuck table for holding a wafer and a cutting means including a cutting blade for cutting the wafer held on the chuck table, and the chuck table and the cutting means are relatively moved. The present invention relates to a wafer cutting method in which a plurality of devices are partitioned by a planned separation line on which test elements are formed by cutting feed and indexing, and the wafer separation planned line is cut and divided into individual devices. The cutting blade is cut in the state where the cutting blade portion of the cutting blade is positioned within the planned separation line and the center of the test element in the width direction does not match the center of the cutting blade in the width direction. It is also characterized by cutting the planned separation line.

  When the planned separation line is an area formed between a first boundary line that is a boundary line with the device on one side and a second boundary line that is a boundary line with the device on the other side, It is desirable that the center in the width direction of the cutting blade portion is alternately positioned near the first boundary line and the second boundary line with reference to the center in the width direction of the test element, and the planned separation lines are sequentially cut.

  The second invention relates to a cutting apparatus suitable for carrying out the above wafer cutting method, a chuck table for holding a wafer, a cutting means including a cutting blade for cutting a wafer held on the chuck table, and a chuck table. At least a cutting feed means for relatively cutting and feeding the cutting table and the cutting means, and an index feeding means for relatively indexing and feeding the chuck table and the cutting means. It has a function of cutting and cutting the cutting blade of the wafer formed by dividing and feeding the predetermined separation line of the wafer formed by dividing and feeding a plurality of devices by the planned separation line on which the test element is formed, and cutting the cutting blade. The blade is located within the line to be separated and the center of the test element in the width direction and the center of the cutting blade in the width direction. It characterized in that it has a positioning means for positioning the do not match the position.

  When the planned separation line is an area formed between a first boundary line that is a boundary line with the device on one side and a second boundary line that is a boundary line with the device on the other side, The positioning means preferably has a function of positioning the center in the width direction of the cutting blade closer to the first boundary line or closer to the second boundary line with reference to the center in the width direction of the test element.

  In the present invention, since the separation line is cut in a state where the center in the width direction of the cutting blade portion of the cutting blade is shifted from the center in the width direction of the test element, the test element is cut in the width direction of the cutting blade. The central portion in the width direction of the cutting blade portion is not worn in a concave shape without being cut at the central portion. Therefore, it is possible to prevent large chipping from reaching the device due to cutting after the cutting blade portion is worn.

  In addition, when the planned separation line is an area formed between a first boundary line that is a boundary line with the device on one side and a second boundary line that is a boundary line with the device on the other side Is to sequentially cut the line to be separated by sequentially positioning the center in the width direction of the cutting edge portion near the first boundary line and the second boundary line based on the center in the width direction of the test element, Uneven wear in which only one surface side of the cutting blade portion is worn can be prevented.

  A cutting apparatus 1 shown in FIG. 1 carries a wafer cassette mounting portion 2 on which a wafer cassette C that accommodates wafers W is mounted, a wafer before cutting from the wafer cassette C to a temporary placement region 3, and a post-cutting wafer. Loading / unloading means 4 for loading the wafer into the wafer cassette C from the temporary placement area 3, a chuck table 5 that holds the wafer to be cut and can be rotated and moved in the X-axis direction, the chuck table 5, and the temporary placement area 3 A first transfer means 6a for transferring the wafer between them, an alignment means 7 for detecting an area to be cut by imaging the surface of the wafer held on the chuck table 5, and a wafer held on the chuck table 5 Cutting means 8 for cutting, cleaning means 9 for cleaning the wafer after cutting, and transporting the wafer after cutting from the chuck table 5 to the cleaning means 9 And a second transport means 6b.

  As shown in FIG. 2, the chuck table 5 can be cut and fed in the X-axis direction by the cutting feed means 11. The cutting feed means 11 includes a ball screw 110 disposed in the X-axis direction, a pulse motor 111 coupled to one end of the ball screw 110, and a pair of guide rails 112 disposed in parallel with the ball screw 110. A nut (not shown) provided at the lower part of the moving base 113 is screwed into the ball screw 110. The ball screw 110 is driven and rotated by the pulse motor 111, and accordingly, the moving base 113 is guided by the guide rail 112 and moves in the X-axis direction, and the chuck table 5 also moves in the same direction. Yes. The chuck table 5 is driven to rotate by a pulse motor 114 fixed to the upper part of the moving base 113.

  The cutting means 8 has a configuration in which a cutting blade 82 is attached to the tip of a spindle 81 rotatably supported by a housing 80, and the housing 80 is supported by a support portion 83.

  The alignment means 7 is fixed to the side portion of the housing 80. The alignment unit 7 includes an imaging unit 70 that images a wafer, and based on the image acquired by the imaging unit 70, a separation line to be cut can be detected. As shown in FIG. 3, the center line 820a in the width direction (Y-axis direction) of the cutting blade part 820 of the cutting blade 82 is normally the alignment reference line 70a formed at the center of the lens constituting the imaging unit 70. It is adjusted in advance so as to be positioned on the extension line. In FIG. 3, the thickness of the cutting blade portion 820 is exaggerated, but the actual thickness is about several tens of μm.

  Referring to FIG. 2, the cutting means 8 and the alignment means 7 can be moved in the Z-axis direction by the cutting feed means 12. The notch feeding means 12 includes a ball screw 121 disposed in the Z-axis direction on one surface of the wall 120, a pulse motor 122 that rotates the ball screw 121, and a guide rail 123 disposed in parallel with the ball screw 121. A nut (not shown) inside the support portion 83 is screwed into the ball screw 121 and a side portion of the support portion 83 is in sliding contact with the guide rail 123. The support portion 83 is driven by the pulse motor 122 and is guided by the guide rail 123 as the ball screw 121 rotates, and moves up and down in the Z-axis direction. The cutting means 8 supported by the support portion 83 also moves in the Z-axis direction. It is configured to move up and down.

  The cutting means 8 and the alignment means 7 can be moved in the Y-axis direction by the index feeding means 13. The index feeding means 13 includes a ball screw 130 disposed in the Y-axis direction, a moving base 131 integrally formed with the wall 120 and screwed into the ball screw 130, and a pulse motor that rotates the ball screw 130. 132 and a guide rail 133 disposed in parallel with the ball screw 130, and a nut (not shown) inside the moving base 131 is screwed into the ball screw 130. The moving base 131 is driven by the pulse motor 132 and is guided by the guide rail 133 as the ball screw 130 is rotated, and moves in the Y-axis direction. In accordance with this, the cutting means 8 also moves in the Y-axis direction. It has a configuration.

  The positioning motor 14 controls the pulse motor 122 constituting the cutting feed means 12 and the pulse motor 132 constituting the index feeding means 13. The positioning means 14 can precisely control the position of the cutting means 8 in the Y-axis direction and the Z-axis direction according to the number of pulses sent to the pulse motors 122 and 132.

  As shown in FIG. 4, the wafer W to be cut is attached to the tape T, supported integrally with the ring frame F attached to the outer peripheral edge of the tape T, and the wafer cassette shown in FIG. 1. A plurality are accommodated in C. On this wafer W, a plurality of devices D are partitioned and formed by scheduled separation lines S formed vertically and horizontally, and test elements 10 for characteristic evaluation are formed in the scheduled separation lines S. In the example shown in the figure, the test element 10 is formed in the central portion of the scheduled separation line S.

  The planned separation line S is an area formed between the first boundary line S1 and the second boundary line S2, and the first boundary line S1 and the second boundary line S2 are connected to the device D and the planned separation line S. Partitioning. An area having a width of about several μm called a guard ring may be formed between the first boundary line S1 and the second boundary line S2 and each device D. The guard ring is an area provided to prevent chipping caused by cutting of the separation line from reaching the device.

  Referring to FIG. 1, the wafers W accommodated in the wafer cassette C while being supported by the ring frame F are taken out one by one by the carry-in / out means 4 to the temporary placement region 3, and the first transport means. It is adsorbed by 6a, conveyed to the chuck table 5, and held.

  Next, when the chuck table 5 moves in the + X direction, the wafer W is positioned immediately below the alignment unit 7, and based on the image acquired by the imaging unit 70 that constitutes the alignment unit 7, the separation schedule to be cut is to be cut. The line is detected and the Y-axis direction alignment between the scheduled separation line and the cutting blade 81 constituting the cutting means 8 is performed.

  Specifically, as shown in FIG. 3, the center line 820 a in the width direction of the cutting blade portion 820 is adjusted in advance so as to be positioned on an extension line of the alignment reference line 70 a formed in the imaging unit 70. 4, when the test element 10 is formed at the center of the planned separation line S, as shown in FIG. 5, the center line 820a in the width direction of the cutting edge 820 and the test element For example, as shown in FIG. 5, the center line 820a is closer to the first boundary line S1 and the cutting edge 820 is connected to the first boundary line S1 and the first center line 10a. The positioning means 14 shown in FIG. 1 is pulsed so that the allowable chipping that can normally occur by cutting does not reach the device D on the first boundary line S1 side inside the two boundary line S2. Control the motor 132 And it allows the cutting means 8 and the alignment means 7 by precisely moved in the Y-axis direction, to align the cutting blade 82. In the example shown in FIG. 5, for example, when the width of the planned separation line S is 80 μm and the width of the test element 10 is 40 μm, the thickness of the cutting edge 820 is about 50 μm.

  After such alignment, as shown in FIG. 6, while the cutting blade 82 rotates at a high speed, the cutting means 8 is lowered (cut-in feed) and the wafer W held on the chuck table 5 is X The separation planned line S is cut by moving in the axial direction (cutting feed). Further, by performing the same cutting while indexing and feeding the cutting means 8 in the Y-axis direction at intervals of adjacent separation lines S, the separation lines S are cut one after another. At the time of alignment, the center line 820a of the cutting blade portion 820 of the cutting blade 82 is positioned closer to the first boundary line S1, so that the cutting blade portion 820 moves toward the first boundary line S1 as shown in FIG. In the shifted state, the cut is made in the separation line S, and the outer periphery (lower end in FIG. 7) of the cutting blade portion 820 does not contact the entire surface of the test element 10, and the non-contact portion is not cut. Therefore, as shown in FIG. 8, the kerf G1 is formed at a position shifted from the center of the scheduled separation line S toward the first boundary line S1 and inside the first boundary line and the second boundary line. The cutting feed may be configured such that the positional relationship between the chuck table 5 and the cutting means 8 changes relatively in the X-axis direction, and the cutting means 8 moves in the X-axis direction. Further, regarding the indexing and feeding, the positional relationship between the chuck table 5 and the cutting means 8 only needs to change relatively in the Y-axis direction, and the chuck table 5 may be configured to move in the X-axis direction. Further, with regard to the cutting feed, it is sufficient that the positional relationship between the chuck table 5 and the cutting means 8 is relatively changed in the Z-axis direction, and the chuck table 5 may be moved up and down.

  When cutting is performed in this manner, as shown in FIG. 9, only the portion of the cutting blade portion 820 that is in contact with the test element 10 is worn. Then, it was confirmed that if the cutting was further continued in such a worn state, no large chipping to reach the device occurred and the device was not damaged.

  Further, after the cutting blade portion 820 is worn as shown in FIG. 9, the cutting means 8 is indexed and fed in the Y-axis direction by the index feeding means 13 shown in FIG. The cutting blade portion 820 of the cutting blade 82 is roughly positioned on the line. Then, as shown in FIG. 10, the cutting edge 820 is positioned closer to the second boundary line S2 by the control by the positioning means 14 (see FIG. 1), the wafer W is moved in the X-axis direction, and the separation is scheduled. The line S is cut at a position where the allowable chipping that can normally occur by cutting does not reach the device D on the second boundary line S2. Then, as shown in FIG. 11, a kerf G2 is formed at a position shifted from the center of the planned separation line S toward the second boundary line S2 and inside the first boundary line S1 and the second boundary line S2. The Then, as shown in FIG. 12, the cutting blade portion 820 is worn on the side of the cutting blade portion 820 in FIG. In this manner, by cutting alternately the side close to the first boundary line S1 and the side close to the second boundary line S2, it is possible to avoid uneven wear on only one surface side of the cutting blade portion 820. be able to.

  In the above example, the case where the wafer on which the test element 10 is formed at the center of the separation line S is cut has been described. However, the test element 10 is located at the center of the separation line S as shown in FIG. If the alignment reference line 70a is positioned on the extended line of the center line 820a in the width direction of the cutting blade 820, the alignment reference line 70a and the planned separation line are aligned in the alignment. When matching with the center of S, the position deviated from the center of the test element 10 is cut, so that the cutting edge 820 has the shape shown in FIG. 9 and a large chipping leading to the device occurs. Therefore, the device can be prevented from being damaged. Depending on the degree of deviation of the test element 10, fine adjustment of the position of the cutting blade 82 by the positioning means (see FIG. 1) may be necessary.

  Further, as shown in FIG. 14, the test element 10 is at the center of the planned separation line S, and the center line 820a of the cutting edge 820 is not on the extension line of the alignment reference line 70a, and there is a deviation of about several μm. In some cases, the position shifted from the center of the test element 10 can be cut by matching the center line of the planned separation line S with the alignment reference line 70a and performing cutting in this state. Therefore, the cutting edge portion 820 is worn as shown in FIG. 9, and large chipping that reaches the device does not occur. In this case as well, depending on the degree of deviation between the center line 820a of the cutting blade portion 820 and the alignment reference line 70a, fine adjustment of the position of the cutting blade 82 by the positioning means (see FIG. 1) may be required. . For an accurate value of the amount of deviation, a trial cutting is performed with the center of the planned separation line S and the alignment reference line 70a being matched, and the formed kerf and the center of the planned separation line S are separated. It can be grasped by calculating the distance. And the positioning means 14 should just perform control based on the value.

It is a perspective view which shows an example of a cutting device. It is a perspective view which shows the internal structure of the cutting device. It is explanatory drawing which shows an example of the relationship between the cutting blade part of a cutting blade, and the alignment reference line of an imaging part. It is a perspective view which shows the wafer supported by the ring frame via the tape. It is explanatory drawing which shows an example of the relationship between the center of the width direction of the cutting-blade part of a cutting blade, and the center of the element for a test. It is a perspective view which shows the state which cuts the separation planned line of a wafer. It is sectional drawing which shows roughly the state which cuts the 1st boundary line vicinity of a separation plan line. It is a top view which shows the kerf formed near the 1st boundary line of the separation plan line. It is explanatory drawing which expands and shows the outer peripheral part of the cutting-blade part which was worn by cutting near the 1st boundary line of the separation plan line. It is sectional drawing which shows roughly the state which cuts the 2nd boundary line side of the separation plan line. It is a top view which shows the kerf formed near the 2nd boundary line of the separation plan line. It is explanatory drawing which expands and shows the outer peripheral part of the cutting-blade part which abraded by cutting near the 2nd boundary line of the separation plan line. It is explanatory drawing which shows an example of the relationship between the center of the width direction of the cutting-blade part of a cutting blade, and the center of the element for a test. It is explanatory drawing which shows an example of the relationship between the center of the width direction of the cutting-blade part of a cutting blade, and the center of the element for a test. It is a top view which shows the kerf formed in the center of the separation plan line. It is sectional drawing which shows schematically the state which cuts the center of the separation plan line. It is explanatory drawing which expands and shows the outer peripheral part of the cutting-blade part which was worn by cutting the center of a separation plan line.

Explanation of symbols

1: Cutting device 2: Wafer cassette placement unit 3: Temporary placement area 4: Loading / unloading unit 5: Chuck table 6a: First transfer unit 6b: Second transfer unit 7: Alignment unit 70: Imaging unit 70a: Alignment Reference line 8: Cutting means 80: Housing 81: Spindle 82: Cutting blade 820: Cutting blade part 820a: Center line in the width direction 83: Support part 9: Cleaning means 11: Cutting feed means 110: Ball screw 111: Pulse motor 112: Guide rail 113: Moving base 114: Pulse motor 12: Cut feed means 120: Wall part 121: Cut feed means 122: Pulse motor 123: Guide rail
13: Index feeding means 130: Ball screw 131: Moving base 132: Pulse motor 133: Guide rail 14: Positioning means W: Wafer S: Line to be separated 10: Test element S1: First boundary line S2: Second boundary line D: Device G1, G2: Cut groove F: Ring frame T: Tape

Claims (4)

A cutting apparatus comprising at least a chuck table for holding a wafer and a cutting means including a cutting blade for cutting the wafer held on the chuck table is used, and the chuck table and the cutting means are relatively cut and fed. A wafer cutting method for indexing and feeding, and cutting a predetermined separation line of a wafer formed by dividing a plurality of devices by a predetermined separation line on which test elements are formed and dividing the wafer into individual devices,
The cutting blade in a state where the cutting blade portion of the cutting blade is positioned within the planned separation line at a position where the center in the width direction of the test element does not coincide with the center in the width direction of the cutting blade portion. A wafer cutting method in which a part is cut to cut the line to be separated.   The planned separation line is a region formed between a first boundary line that is a boundary line with a device on one side and a second boundary line that is a boundary line with a device on the other side, The center of the cutting blade portion in the width direction is alternately positioned near the first boundary line and the second boundary line with reference to the width direction center of the test element, and the separation lines are sequentially cut. Item 2. A method for cutting a wafer according to Item 1. A chuck table for holding a wafer, a cutting means including a cutting blade for cutting the wafer held on the chuck table, a cutting feed means for relatively cutting and feeding the chuck table and the cutting means, and the chuck table And an indexing feed means for relatively indexing and feeding the cutting means and the cutting table, and the chuck table and the cutting means are relatively cut and fed to each other to form a test line. A cutting apparatus for cutting a predetermined separation line of a wafer formed by partitioning a plurality of devices and dividing them into individual devices,
A cutting apparatus having positioning means for positioning the cutting blade portion of the cutting blade at a position within the planned separation line at a position where the center in the width direction of the test element does not coincide with the center in the width direction of the cutting blade portion. The separation planned line is an area formed between a first boundary line that is a boundary line with a device on one side and a second boundary line that is a boundary line with a device on the other side,
The positioning means has a function of positioning the center in the width direction of the cutting blade closer to the first boundary line or closer to the second boundary line with respect to the center in the width direction of the test element. The cutting device described.

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