JP4554265B2 - Method for detecting misalignment of cutting blade - Google Patents

Description

  The present invention relates to a method for detecting a positional deviation of a cutting blade mounted on a cutting apparatus.

  A semiconductor wafer formed by partitioning a plurality of semiconductor devices by streets is divided into individual semiconductor chips by cutting the streets by a cutting blade constituting a dicing apparatus, and is used for various electronic devices.

  In a dicing apparatus, a semiconductor wafer is held on a chuck table, a street to be cut is detected, and after alignment of the street and the cutting blade is performed, a cutting blade that rotates at high speed cuts into the street. By doing so, cutting is performed. Since the cutting blade is mounted on the spindle, the position of the cutting blade is shifted due to thermal expansion accompanying high-speed rotation of the spindle. This misalignment causes the cutting blade to cut a position off the street, resulting in a problem that the device region is damaged or the quality is degraded.

  Further, when the cutting blade is replaced with a new cutting blade, the mounting state of the spindle changes, and a positional deviation may occur between the cutting blade before the replacement.

  Therefore, in the middle of cutting semiconductor wafers, we also propose a technology that projects the cutting grooves formed on the semiconductor wafer, detects the deviation between the center of the image and the cutting groove, and controls the movement of the blade in consideration of the deviation. However, since it is difficult to detect the cutting groove due to irregular reflection on the wafer surface, for example, a technique described in Patent Document 1 has been proposed.

  However, in the technique disclosed in Patent Document 1, a groove is formed in the adhesive tape attached to the semiconductor wafer by overrunning the semiconductor wafer during cutting, and the deviation is measured based on the position of the groove. Since the semiconductor wafer has already been cut at the measurement stage, it is not possible to prevent erroneous cutting (cutting in a state where positional deviation has occurred).

  In addition, since the thickness of the cutting blade is usually as thin as about 20 μm and has flexibility, when a hard member such as a semiconductor wafer is cut from the front surface side, the cutting blade is slightly curved from the front surface and the back surface is curved. It will lead to the adhesive tape affixed to. In addition, when the cutting target is a semiconductor wafer, the cutting blade may be bent under the influence of the crystal orientation. Therefore, the groove formed in the adhesive tape due to the overrun does not coincide with the position of the groove on the surface of the semiconductor wafer. Therefore, the positional deviation of the cutting blade cannot be accurately measured from the groove formed in the adhesive tape. Can not. The above problems also occur when cutting plate-like objects other than semiconductor wafers.

Japanese Patent No. 3280736

  Therefore, the problem to be solved by the present invention is to accurately detect the positional deviation of the cutting blade, prevent the erroneous cutting in advance, and accurately cut the desired position of the plate-like object. .

The present invention provides a chuck table for holding a plate-like object, a cutting means including a cutting blade for cutting the plate-like object held on the chuck table, and an optical system in which a reference line for alignment of the cutting blade is formed. A method for detecting misalignment of a cutting blade in a cutting apparatus having an alignment means for detecting a scheduled cutting area of a plate-like object, and assuming that there is a certain positional relationship between the reference line and the cutting blade In addition, the first step of aligning the planned cutting area and the reference line, and the plate-like object are integrated with the dicing frame via the dicing tape, and the planned cutting area and the reference line are aligned. the preset cutting area cutting state, a second step of dividing the plate-like material by cutting a plurality of cutting-scheduled region while feeding index cutting means by preset cutting area interval, the second step Along the way, independently from the cutting of the cutting region where, by cut the cutting blade on the exposed portion of the plate-like object and the dicing frame of the dicing tape is not adhered to form the cutting scratch, the alignment means The sections Kezukizu And at least a third step of detecting misalignment between the cutting flaw and the reference line. When detecting misalignment multiple times during processing, the chuck table is formed after forming the cutting flaw. Is rotated by a required angle to form another cutting flaw that does not overlap with the cutting flaw on the exposed portion of the dicing tape .

  In the present invention, apart from the second step of cutting an actual plate-like object, a cutting defect is formed by cutting the plate-like object non-existing region in the third step, and the cutting flaw is detected by the alignment means. By detecting the positional deviation between the cutting flaw and the reference line, the cutting blade is not curved, so that the position of the cutting blade is transferred as it is to the area where there is no plate-like object, and the positional deviation of the cutting blade is accurately detected. In addition, it is possible to detect misalignment before cutting the plate-like object, and to prevent erroneous cutting.

Further, plate-like material has become integrated with the dicing frame through a dicing tape, of the dicing tape, by the exposed portion of the plate-like object and the dicing frame is not attached to the plate-like material absence region Cutting flaws can be formed easily and efficiently.

In addition, the position of the cutting blade can be determined as many times as necessary based on the newly formed cutting flaw by rotating the chuck table by the required angle after forming the cutting flaw to form another cutting flaw that does not overlap with the cutting flaw. The deviation can be detected accurately, and the case where the position deviation of the cutting blade is frequently detected can be dealt with.

  A cutting apparatus 1 shown in FIG. 1 is an example of an apparatus used for carrying out the present invention, and includes a chuck table 2 that holds a plate-like object and a cutting blade 31 that cuts the plate-like object held on the chuck table 2. A cutting means 3 and an alignment means 4 having an optical system 40 on which a reference line for alignment is formed and detecting a scheduled cutting area of the plate-like object are provided.

  The chuck table 2 can be moved in the X-axis direction by the X-axis feed mechanism 5 and can be rotated by the rotation drive mechanism 6. The chuck table feed mechanism 5 includes a ball screw 50 arranged in the X-axis direction, a drive source 51 connected to one end of the ball screw 50 and rotating the ball screw 50, and a pair of guide rails arranged in parallel with the ball screw 50. 52 and a moving base 53 in which a nut is slidably engaged with the guide rail 52 and an internal nut is screwed into the ball screw 50, and the ball screw 50 is rotated by being driven by the drive source 51. Accordingly, the moving base 53 is guided by the guide rail 52 and moves in the X-axis direction. On the other hand, the rotation drive mechanism 6 has a rotation drive unit 60 fixed to the moving base 53 and connected to the chuck table 2, and is driven by the rotation drive unit 60 so that the chuck table 2 rotates by a required angle. It has become. The drive source 51 and the rotation drive unit 60 are controlled by the control unit 9.

  The cutting means 3 includes a spindle 30 disposed in the Y-axis direction, a cutting blade 31 attached to the tip of the spindle 30, and a spindle housing 32 that rotatably supports the spindle 30. The feed mechanism 7 can move in the Z-axis direction, and the Y-axis feed mechanism 8 can move in the Y-axis direction. The Z-axis feed mechanism 7 is driven by the Y-axis feed mechanism 8 and is movable in the Y-axis direction, and a ball screw (not shown) disposed in the vertical direction along one surface of the wall 70. ), A drive source 71 connected to one end of the ball screw and rotating the ball screw, a pair of guide rails 72 arranged parallel to the ball screw, and a slidably engaged with the guide rail 72 and an internal nut The support portion 73 is engaged with the ball screw and supports the cutting means 3. The support portion 73 is guided by the guide rail 72 and driven in the Z-axis direction as the ball screw rotates by being driven by the drive source 71. It is configured to move to. The drive source 71 is controlled by the control unit 9.

  On the other hand, the Y-axis feed mechanism 8 includes a ball screw 80 disposed in the Y-axis direction, a drive source 81 connected to one end of the ball screw 80 and rotating the ball screw 80, and a pair of balls screw 80 disposed in parallel. The guide rail 82 includes a guide base 82 slidably engaged with the guide rail 82 and a moving base 83 in which an internal nut is screwed into the ball screw 80. The ball screw 80 is rotated by being driven by a drive source 81. Accordingly, the moving base 83 is guided by the guide rail 82 and moves in the X-axis direction, and the wall portion 70 erected from the moving base 83 is also moved in the Y-axis direction. The drive source 81 is controlled by the control unit 9.

  The alignment means 4 is fixed to a spindle housing 32 constituting the cutting means 3, and the cutting means 3 and the alignment means 4 are configured to move together in the Y-axis direction and the Z-axis direction. The alignment unit 4 includes an optical system 40 having an optical axis in the Z-axis direction, and an imaging unit 41 that converts an image acquired by the optical system 40 into an electrical signal, and based on the image acquired by the imaging unit 41. The control unit 9 detects the planned cutting area of the plate-like object by processing such as pattern matching. As shown in FIG. 2, a reference line 400 is formed in the X-axis direction on the lens of the optical system 40, and the cutting blade 31 is positioned on an extension line of the reference line 400, that is, the cutting blade 31. And the Y coordinate of the reference line 400 are adjusted to match.

  For example, when dicing a semiconductor wafer, the semiconductor wafer W is held on the chuck table 2 in a state of being integrated with the dicing frame F via the dicing tape T as shown in FIG. The chuck table 2 is moved in the X-axis direction by being driven by the X-axis feed mechanism 5 and is also driven by the Y-axis feed mechanism 8 and the Z-axis feed mechanism 7 so that the alignment means 4 is moved in the Y-axis direction and the Z-axis direction. By moving, the semiconductor wafer W is positioned directly below the optical system 40.

  When the semiconductor wafer W is positioned almost directly below the optical system 40, the surface of the semiconductor wafer W is imaged by the alignment means 4, and the chuck table 2 is moved in the X-axis direction and the optical system 40 is moved in the Y-axis direction. Then, pattern matching between the street image stored in advance in the control unit 9 and the actual image acquired by the imaging unit 41 is performed in the control unit 9 and formed on the surface of the semiconductor wafer W as shown in FIG. The street S, which is the planned cutting area, is detected. In the pattern matching, the center of the detected street S to be cut is matched with the reference line 400. Since the cutting blade 31 is adjusted in advance so as to be positioned on the extended line of the reference line 400, the center of the street S matches the reference line 400 on the assumption that the reference line 400 and the cutting blade 31 match. (First step). As a result, the reference line 400 is located at the center of the street S, and the cutting blade 31 is also located on the extension line at the center of the street. If the reference line 400 and the cutting blade 31 do not completely match, the deviation amount in the Y-axis direction between the reference line 400 and the cutting blade 31 is stored in the control unit 9 as a correction value, and the correction is performed. By adjusting the value, the center of the street S and the reference line 400 may be matched. In other words, it is sufficient that there is a certain positional relationship between the reference line 400 and the cutting blade 31.

  After the alignment, the chuck table 2 further moves in the + X direction, and the cutting blade 31 descends without changing the position in the Y-axis direction while rotating at a high speed, thereby cutting into the street S detected by the alignment. As described above, the detected street S detected in the first step is cut. Next, as shown in FIG. 5, the chuck table 2 is moved back and forth in the X-axis direction while the cutting means 3 is indexed by the street interval in the Y-axis direction to cut each street S in the same direction. . For the streets orthogonal to each other, alignment is performed after the chuck table 2 is rotated 90 degrees, and cutting is performed in the same manner as described above. Then, when all the streets are cut vertically and horizontally, the semiconductor wafer W is diced and divided into individual semiconductor chips (second step). In FIG. 5, the alignment means 4 and the like are not shown.

  When dicing is performed in this manner, the spindle 30 may thermally expand due to the high-speed rotation of the spindle 30, and the position of the cutting blade 31 mounted on the spindle 30 in the Y-axis direction may be displaced. Therefore, independently of the second step, as shown in FIG. 6, the cutting blade 31 is placed on the exposed portion T1 of the dicing tape T, which is a region where no plate-like object exists (plate-like object non-existing region). Cutting is performed to form a cutting flaw 100 as shown in FIG. The exposed portion T1 here is a portion where the semiconductor wafer W and the dicing frame F are not attached. By setting the exposed portion T1 of the dicing tape T to be a plate-like object non-existing region, it is possible to easily and efficiently form a cutting flaw.

  Next, the chuck table 2 is moved in the X-axis direction while maintaining the positions of the cutting means 3 and the alignment means 4 at that time in the Y-axis direction, so that the optical system 40 is positioned immediately above the cutting flaw 100 and imaged. Then, the cutting means 100 is detected by the alignment means 4. As shown in an enlarged view in FIG. 7, when the cutting flaw 100 and the reference line 400 do not match, the cutting blade 31 is not on the extension line of the reference line 400. Therefore, it can be determined that the positional deviation is generated. In the example of FIG. 7, the reference line 400 and the center of the cutting flaw 100 are separated by a distance S1, and the cutting blade 31 is shifted in the −Y direction by S1.

  In this way, in addition to the street cutting, the cutting blade 31 is curved as in the case of overrunning the semiconductor wafer in order to form the cutting flaw 100 in the exposed portion T1 of the dicing tape T that is a plate-like object nonexistence region. The dicing tape T is not cut. Therefore, the cutting flaw 100 accurately indicates the position of the actual cutting blade 31 in the Y-axis direction, and the positional deviation amount S1 obtained based on the cutting flaw 100 is an accurate value. Further, since misalignment is not detected after the street is cut, it is possible to prevent miscutting of the street in a state where the misalignment has occurred.

  As shown in FIG. 8, the semiconductor wafer W is rotated along with the rotation of the chuck table 2, and then the cutting blade 31 is cut into the plate-like object non-existing region T <b> 1 of the dicing tape T to form the second cutting flaw 101. You can also Then, while maintaining the position of the alignment means 4 in the Y-axis direction, the chuck table 2 is moved in the X-axis direction, the optical system 40 is positioned immediately above the second cutting flaw 101, and an image is taken. If 101 is detected, the presence / absence of the positional deviation of the cutting blade 31 and the positional deviation amount S2 can be detected based on whether or not the second cutting flaw 101 and the reference line 400 match. Further, as shown in FIG. 9, the semiconductor wafer W can be further rotated to form the third cutting flaw 102 to detect whether or not the cutting blade 31 is misaligned and the misalignment amount S <b> 3. In this way, the positional deviation of the cutting blade 31 can be detected even during the dicing of one semiconductor wafer.

  By forming the cutting flaw after rotating the semiconductor wafer W, the cutting flaw can be formed a plurality of times. Since a plurality of cutting flaws can be formed without overlapping, the positional deviation amount of the cutting blade 31 can be accurately detected sequentially based on the respective cutting waste. In addition, by rotating the chuck table 2, a large number of cutting flaws can be formed on one dicing tape, so that the dicing tape T can be used repeatedly. The positional deviation of the cutting blade 31 can be accurately detected any number of times based on the formed cutting flaw, and it is possible to easily cope with the case where the positional deviation of the cutting blade 31 frequently occurs.

  A plurality of cutting flaws can be formed on the dicing tape T by shifting the position of the cutting blade 31 in the Y-axis direction without rotating the chuck table 2.

  If the positional deviation amount of the cutting blade 31 is obtained as described above, the positional deviation amount value is notified from the alignment means 4 to the control unit 9 as shown in FIG. In the actual cutting, the center of the street can be cut by the control unit 9 correcting the position of the cutting blade 31 in the Y-axis direction in consideration of the amount of displacement. Further, by adjusting the mounting state of the cutting blade 31 so that the cutting flaw and the reference line 400 coincide with each other, a desired position on the street can be cut accurately.

It is a perspective view which shows an example of the cutting device used for implementation of this invention. It is explanatory drawing which shows the relationship between a cutting blade and the reference line of an optical system. It is explanatory drawing which shows the relationship between the cutting blade at the time of detecting a street, and a street. It is a top view which shows a mode that the detected street is cut. It is a perspective view which shows a mode that a street is cut sequentially. It is a perspective view which shows a mode that a cutting flaw is formed. It is explanatory drawing which shows the position shift with a cutting flaw and a reference line. It is explanatory drawing which shows the position shift with a 2nd cutting flaw and a reference line. It is explanatory drawing which shows the position shift with a 3rd cutting flaw and a reference line.

1: Cutting device 2: Chuck table 3: Cutting means 30: Spindle 31: Cutting blade 32: Spindle housing 4: Alignment means 40: Optical system 41: Imaging unit 400: Reference line 5: X-axis feed mechanism 50: Ball screw 51: Drive source 52: Guide rail 53: Moving base 6: Rotation drive mechanism 60: Rotation drive unit 7: Z-axis feed mechanism 70: Wall portion 71: Drive source 72: Guide rail 73: Support unit 8: Y-axis feed mechanism 80 : Ball screw 81: Drive source 82: Guide rail 83: Moving base 9: Control unit 100: Cutting flaw 101: Second cutting flaw 102: Third cutting flaw

Claims (1)

A chuck table for holding the plate-like object, a cutting means including a cutting blade for cutting the plate-like object held on the chuck table, and an optical system in which a reference line for alignment of the cutting blade is formed. A method for detecting misalignment of a cutting blade in a cutting apparatus comprising an alignment means for detecting a planned cutting area of the plate-like object,
Assuming that there is a certain positional relationship between the reference line and the cutting blade, a first step of aligning the planned cutting area and the reference line;
The plate-like object is integrated with a dicing frame via a dicing tape, the planned cutting area is cut in a state where the planned cutting area and the reference line are aligned, and the planned cutting area intervals are divided by the cutting target area. A second step of dividing the plate-like object by cutting a plurality of scheduled cutting areas while feeding the cutting means with an index;
In the middle of the second step, the cutting blade is cut into the exposed portion of the dicing tape where the plate-like object and the dicing frame are not attached independently of the cutting of the planned cutting area. Forming a flaw, and comprising at least a third step of detecting a positional deviation between the cutting flaw and the reference line by detecting the cutting flaw by the alignment means ,
When detecting misalignment multiple times during processing, after forming the cutting flaw, the chuck table is rotated by a required angle, and another cutting flaw that does not overlap with the cutting flaw is removed from the exposed portion of the dicing tape. A method for detecting misalignment of a cutting blade to be formed .

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