JP4903445B2 - How to check the cutting blade depth - Google Patents

Description

  The present invention relates to a cutting blade cutting confirmation method for checking whether or not a cutting blade is cut perpendicular to a workpiece when a workpiece such as a semiconductor wafer is cut by a cutting device.

  In the semiconductor device manufacturing process, a plurality of regions are partitioned by dividing lines called streets arranged in a lattice pattern on the surface of a substantially wafer-shaped semiconductor wafer, and devices such as ICs, LSIs, etc. are partitioned in the partitioned regions. Form. Then, the semiconductor wafer is cut along the streets to divide the region in which the device is formed to manufacture individual semiconductor chips. In addition, optical device wafers with gallium nitride compound semiconductors laminated on the surface of a sapphire substrate are also divided into individual optical devices such as light emitting diodes and laser diodes by cutting along the streets, and are widely used in electrical equipment. ing.

Cutting along the streets of the above-described semiconductor wafer, optical device wafer or the like is usually performed by a cutting device called a dicer. This cutting apparatus moves a chuck table for holding a workpiece such as a semiconductor wafer, a cutting means for cutting the workpiece held on the chuck table, and the chuck table and the cutting means relative to each other. Cutting feed means. The cutting means includes a spindle unit having a rotary spindle, a cutting blade mounted on the spindle, and a drive mechanism for driving the rotary spindle to rotate. The cutting blade is composed of an ultra-thin whetstone blade in which diamond abrasive grains are solidified by nickel plating to a thickness of 15 to 30 μm. The cutting blade formed in this way is positioned at the center of the 30-50 μm width formed on the wafer, and cuts and feeds the wafer along the street with high accuracy by cutting and feeding a predetermined amount. Disconnect. (For example, refer to Patent Document 1.)
JP 2001-77055 A

  Therefore, when the protruding state of the diamond abrasive grains forming the cutting blade is different between one surface and the other surface of the cutting blade or when clogging occurs, the cutting blade is When cut, the cutting blade tends to escape in the direction of lower cutting resistance. As a result, even if the cutting blade is positioned perpendicular to the wafer, there is a problem in that the wafer is cut obliquely and the quality of the device is degraded. Even if the cutting blade cuts the wafer diagonally, this diagonal cutting is only found after the cutting of one wafer is completed and the cut surface of the device is confirmed with a microscope or the like. There is a problem that it is not possible to confirm that the cutting blade is cutting the wafer at an angle during the process, leading to a decrease in yield.

  The present invention has been made in view of the above facts, and the main technical problem thereof is whether or not the cutting blade is accurately cut into the workpiece even during the cutting operation of the workpiece. It is an object of the present invention to provide a cutting blade incision confirmation method capable of confirming the above.

In order to solve the main technical problem, according to the present invention, a chuck table for holding a workpiece, a cutting means having a cutting blade for cutting the workpiece held on the chuck table, and the cutting blade A cutting device comprising a cutting water supply means for supplying cutting water to a cutting portion by means of an image and an imaging means for picking up an image of the surface of a workpiece held on the chuck table is used. A cutting blade cutting confirmation method for checking whether or not the cutting blade is cut perpendicularly to the workpiece when the workpiece is cut to form a cutting groove while supplying ,
Air that blows air on the cutting groove formed in the workpiece to blow off the upper part of the cutting water immersed in the cutting groove, and makes the surface of the cutting water immersed in the cutting groove concave by the action of surface tension. Blowing process;
A cutting groove imaging step of imaging the cutting groove, positioning the cutting groove formed in the workpiece subjected to the air blowing step directly below the imaging means;
Determining whether or not the reflected light of the cutting water immersed in the cutting groove is positioned at the center of the width of the cutting groove based on the image picked up in the cutting groove imaging step. ,
The determination step determines that the cutting blade is cut perpendicular to the workpiece when the reflected light of the cutting water is located at the center of the width of the cutting groove, and the reflected light of the cutting water Is determined that the cutting blade is not cut perpendicularly to the workpiece when the cutting groove is not located in the center of the width of the cutting groove,
There is provided a cutting blade cutting confirmation method characterized by the above.

In the cutting blade cutting confirmation method according to the present invention , air is blown to the cutting groove formed in the workpiece by the cutting blade to blow off the upper portion of the cutting water immersed in the cutting groove , and the cutting blade is immersed in the cutting groove . After making the surface of the cutting water concave by the action of surface tension, the cutting groove formed in the work piece is imaged by the cutting blade, and the reflected light of the cutting water immersed in the cutting groove based on the imaged image is reflected. Since it is determined whether or not the cutting groove is positioned in the center of the width of the cutting groove and whether or not the cutting blade is accurately cut into the work piece, Even if it exists, the cutting | disconnection confirmation of a cutting blade can be implemented.

  Hereinafter, a preferred embodiment of a cutting blade cutting confirmation method according to the present invention will be described in more detail with reference to the accompanying drawings.

  FIG. 1 shows a perspective view of a cutting apparatus for carrying out the cutting blade cutting confirmation method according to the present invention. The cutting device in the illustrated embodiment includes a device housing 2 having a substantially rectangular parallelepiped shape. In the apparatus housing 2, a chuck table 3 for holding a workpiece is disposed so as to be movable in a direction indicated by an arrow X that is a cutting feed direction. The chuck table 3 includes a suction chuck support 31 and a suction chuck 32 disposed on the suction chuck support 31. A workpiece is illustrated on a holding surface which is the upper surface of the suction chuck 32. Suction holding is performed by operating a suction means that does not. The chuck table 3 is configured to be rotatable by a rotation mechanism (not shown). The chuck table 31 is provided with a clamp 33 for fixing a support frame for supporting a semiconductor wafer, which will be described later, as a workpiece through a protective tape. The chuck table 3 configured as described above can be moved in a cutting feed direction indicated by an arrow X by a cutting feed means (not shown).

  The cutting apparatus in the illustrated embodiment includes a spindle unit 4 as cutting means. The spindle unit 4 is mounted on a moving base (not shown) and is adjusted to move in a direction indicated by an arrow Y that is an indexing direction and a direction indicated by an arrow Z that is a cutting direction. The rotary spindle 42 is supported, and a cutting blade 43 attached to the front end of the rotary spindle 42 is provided. The cutting blade 43 is composed of an ultra-thin grindstone blade in which diamond abrasive grains are solidified by nickel plating and have a thickness of 15 to 30 μm. A blade cover 44 that covers the upper half of the cutting blade 43 is attached to the front end of the spindle housing 41. The blade cover 44 is provided with cutting water supply nozzles 45 disposed on both sides of the cutting blade 43 and constituting cutting water supply means. The spindle unit 4 as the cutting means constructed as described above is moved in the index feed direction indicated by the arrow Y in FIG. 1 by the index feed means (not shown) and is indicated by the arrow Z in FIG. 1 by the notch feed means (not shown). It can be moved in the cutting feed direction.

  The cutting apparatus in the illustrated embodiment images the surface of the workpiece held on the chuck table 3, detects a region to be cut by the cutting blade 43, and forms a cutting groove cut by the cutting blade 43. Imaging means 5 for imaging is provided. The imaging means 5 is composed of optical means such as a microscope and a CCD camera. In addition, the cutting apparatus includes a display unit 6 that displays an image captured by the imaging unit 5. Further, the cutting apparatus in the illustrated embodiment includes an air blowing means 7 that blows air onto a workpiece held on the chuck table 3 and cut.

  In the cassette mounting area 8a of the apparatus housing 2, a cassette mounting table 8 for mounting a cassette for storing a workpiece is disposed. The cassette mounting table 8 is configured to be movable in the vertical direction by a lifting means (not shown). On the cassette mounting table 8, a cassette 9 for storing a semiconductor wafer 10 as a workpiece is placed. The semiconductor wafer 10 accommodated in the cassette 9 has a grid-like street formed on the surface thereof, and devices such as IC and LSI are formed in a plurality of rectangular areas partitioned by the grid-like street. The semiconductor wafer 10 thus formed is accommodated in the cassette 9 with the back surface adhered to the front surface of the protective tape 12 mounted on the annular support frame 11.

  Further, the cutting device in the illustrated embodiment is a semiconductor wafer 10 accommodated in a cassette 9 placed on a cassette placement table 8 (a state in which the wafer is supported on an annular frame 11 via a protective tape 12). The unloading means 14 for unloading the semiconductor wafer 10 onto the temporary table 13, the transporting means 15 for transporting the semiconductor wafer 10 unloaded onto the temporary table 13 onto the chuck table 3, and the semiconductor wafer 10 cut on the chuck table 3. Cleaning means 16 for cleaning the semiconductor wafer 10 and cleaning transport means 17 for transporting the semiconductor wafer 10 cut on the chuck table 3 to the cleaning means 16.

A cutting procedure for cutting the semiconductor wafer 10 along a predetermined street using the cutting apparatus configured as described above will be briefly described.
The semiconductor wafer 10 (supported by the annular frame 11 via the protective tape 12) accommodated in a predetermined position of the cassette 9 placed on the cassette placement table 8 is moved by an elevator means (not shown). The mounting table 8 is moved to the carry-out position by moving up and down. Next, the unloading means 14 moves forward and backward, and the semiconductor wafer 10 positioned at the unloading position is unloaded onto the temporary placement table 13. The semiconductor wafer 10 carried out to the temporary placement table 13 is transferred onto the chuck table 3 by the turning operation of the transfer means 15. When the semiconductor wafer 10 is placed on the chuck table 3, suction means (not shown) is operated to suck and hold the semiconductor wafer 10 on the chuck table 3. The support frame 11 that supports the semiconductor wafer 10 via the protective tape 12 is fixed by the clamp 33. In this way, the chuck table 3 holding the semiconductor wafer 10 is moved to a position immediately below the imaging means 5. When the chuck table 3 is positioned immediately below the image pickup means 5, the street formed on the semiconductor wafer 10 is detected by the image pickup means 5, and the spindle unit 4 is moved and adjusted in the arrow Y direction as an indexing direction to cut the street and the cutting. A precision alignment operation with the blade 43 is performed.

  Thereafter, the cutting blade 43 is cut and fed by a predetermined amount in the direction indicated by the arrow Z and rotated in the predetermined direction, while the chuck table 3 holding the semiconductor wafer 10 is sucked and held in the direction indicated by the arrow X (cutting blade 43). The semiconductor wafer 10 held on the chuck table 3 is cut along a predetermined street by the cutting blade 43 (cutting process). In this cutting process, cutting water is supplied from the cutting water supply nozzle 45 to the cutting portion by the cutting blade 43. When the semiconductor wafer 10 is cut along a predetermined street in this way, the chuck table 3 is indexed and fed in the direction indicated by the arrow Y by the street interval, and the above-described cutting process is performed. When the cutting process is performed along all the streets extending in the predetermined direction of the semiconductor wafer 10, the chuck table 3 is rotated 90 degrees to extend in a direction orthogonal to the predetermined direction of the semiconductor wafer 10. By executing the cutting process along the streets, all the streets formed in a lattice shape on the semiconductor wafer 10 are cut and divided into individual chips. Note that the divided chips do not fall apart due to the action of the protective tape 12, and the state of the wafer supported by the frame 11 is maintained.

  As described above, when the cutting process is completed along the street of the semiconductor wafer 10, the chuck table 3 holding the semiconductor wafer 10 is first returned to the position where the semiconductor wafer 10 is sucked and held. Then, the suction holding of the semiconductor wafer 10 is released. Next, the semiconductor wafer 10 is transferred to the cleaning unit 16 by the cleaning transfer unit 17. The semiconductor wafer 10 conveyed to the cleaning means 16 is cleaned and dried here. The semiconductor wafer 10 thus cleaned and dried is transported to the temporary placement table 13 by the transport means 15. Then, the semiconductor wafer 10 is stored in a predetermined position of the cassette 9 by the unloading means 14. Accordingly, the carry-out means 14 also has a function as a carry-in means for carrying the processed semiconductor wafer 10 into the cassette 9.

  In the cutting process described above, the cutting blade 43 for cutting the semiconductor wafer 10 is set to be cut perpendicular to the semiconductor wafer 10 as shown in FIG. However, when the protruding state of the diamond abrasive grains forming the cutting blade 43 is different between one surface and the other surface, or when the cutting blade 43 is clogged, the cutting blade 43 as described above. When cutting into the semiconductor wafer 10, the cutting blade 43 tends to escape in a direction in which the cutting resistance is small, and the cutting blade 43 is cut obliquely as shown by a two-dot chain line in FIG.

As described above, a method for confirming whether or not the cutting blade 43 has been cut perpendicular to the semiconductor wafer 10 will be described with reference to FIGS. 3 and 4.
First, when the first cutting process is performed, the chuck table 3 is moved toward the image pickup means 5 and positioned immediately below the image pickup means 5. At this time, the air blowing means 7 is operated to blow air into the cutting grooves formed in the semiconductor wafer 10 held on the chuck table 3 (air blowing step). This air blowing process is performed when the cutting water immersed in the cutting groove formed in the semiconductor wafer 10 is larger than the upper edge of the cutting groove, the surface becomes convex due to surface tension and the reflected light is accurately reflected. Since it cannot detect, the upper part of cutting water is blown off so that the surface of the cutting water immersed in the cutting groove may become concave. That is, when the upper part of the cutting water immersed in the cutting groove formed in the semiconductor wafer 10 is blown away and the surface of the cutting water falls below the upper edge of the cutting groove, the surface becomes concave due to surface tension.

  If the chuck table 3 is positioned immediately below the image pickup means 5, the cutting groove formed in the semiconductor wafer 10 is imaged by the image pickup means 5 (cutting groove imaging step). The image picked up by the image pickup means 5 is displayed on the display means 6. FIG. 3A shows an image displayed on the display means 6. This image shows that the cutting groove 110 formed in the semiconductor wafer 10 is perpendicular to the semiconductor wafer 10 as shown in FIG. The formed state is shown. As shown in FIG. 3B, the surface of the cutting water immersed in the cutting groove 110 becomes concave due to surface tension. 3B, when the cutting groove 110 formed in the semiconductor wafer 10 is formed perpendicular to the semiconductor wafer 10, the cutting water 120 immersed in the cutting groove 110 is removed. The bottom surface 120 a of the concave surface is the center of the width of the cutting groove 110. In this case, the reflected light 130 appears in the center of the width of the cutting groove 110 in the image picked up by the image pickup means 5 as shown in FIG. Therefore, based on the image displayed on the display means 6, when the reflected light 130 is located at the center of the cutting groove 110, the cutting blade 43 is cut perpendicularly to the semiconductor wafer 10. Determine (determination step).

  Next, in the image shown in FIG. 4A, the cutting blade 43 is not cut perpendicular to the semiconductor wafer 10, and the cutting groove 110 formed in the semiconductor wafer 10 as shown in FIG. 2 shows a state where the semiconductor wafer 10 is formed obliquely. When the cutting groove 110 is formed obliquely with respect to the semiconductor wafer 10, as shown in FIG. 4B, the surface of the cutting water immersed in the cutting groove 110 has the lowest position 120 a at the width of the cutting groove 110. The position is displaced from the center. In this case, reflected light 130 appears in the image picked up by the image pickup means 5 at a position displaced from the center of the width of the cutting groove 110 as shown in FIG. Therefore, when the reflected light 130 is displaced from the center of the cutting groove 110 based on the image displayed on the display means 6, the cutting blade 43 is not cut perpendicularly to the semiconductor wafer 10. Determine (determination step).

  As a result of performing the above-described cutting groove imaging step and determination step, the cutting groove 110 formed in the semiconductor wafer 10 is not formed perpendicular to the semiconductor wafer 10, that is, the cutting blade 43 is perpendicular to the semiconductor wafer 10. If it is determined that the cutting blade is not cut, replace the cutting blade or dress the cutting blade.

  The semiconductor wafer 10 can be cut along the street with high accuracy by performing the above-described cutting groove imaging step and determination step each time the cutting step is performed a predetermined number of times. Therefore, the quality of the device is guaranteed and the yield is not reduced.

The perspective view of the cutting device for enforcing the cutting confirmation method of the cutting blade by this invention. Explanatory drawing which shows the state which is cutting the semiconductor wafer which is a workpiece by the cutting blade with which the cutting apparatus shown in FIG. 1 is equipped. Explanatory drawing which shows the state of the picked-up image and cutting groove in case the cutting groove formed in the semiconductor wafer is formed perpendicularly | vertically with respect to the semiconductor wafer in the cutting confirmation method of the cutting blade by this invention. Explanatory drawing which shows the state of the picked-up image and cutting groove in case the cutting groove formed in the semiconductor wafer is not formed perpendicularly | vertically with respect to the semiconductor wafer in the cutting confirmation method of the cutting blade by this invention. Sectional drawing which shows a scanning method.

Explanation of symbols

2: Device housing 3: Chuck table 4: Spindle unit 43: Cutting blade 5: Imaging means 6: Display means 7: Air blow means 8: Cassette mounting table 9: Cassette 10: Semiconductor wafer (workpiece)
110: Cutting groove 120: Cutting water 130: Reflected light 11: Annular support frame 12: Protection tape 13: Temporary table 14: Unloading means 15: Conveying means 16: Cleaning means 17: Cleaning and conveying means

Claims (1)

A chuck table for holding a workpiece, a cutting means having a cutting blade for cutting the workpiece held on the chuck table, a cutting water supply means for supplying cutting water to a cutting portion by the cutting blade, Using a cutting device having an imaging means for imaging the surface of the workpiece held on the chuck table, the workpiece is cut while forming cutting grooves while supplying cutting water to the cutting portion by the cutting blade. A cutting blade cutting confirmation method for confirming whether or not the cutting blade was cut perpendicularly to the workpiece when
Air that blows air on the cutting groove formed in the workpiece to blow off the upper part of the cutting water immersed in the cutting groove, and makes the surface of the cutting water immersed in the cutting groove concave by the action of surface tension. Blowing process;
A cutting groove imaging step of imaging the cutting groove, positioning the cutting groove formed in the workpiece subjected to the air blowing step directly below the imaging means;
Determining whether or not the reflected light of the cutting water immersed in the cutting groove is positioned at the center of the width of the cutting groove based on the image picked up in the cutting groove imaging step. ,
The determination step determines that the cutting blade is cut perpendicular to the workpiece when the reflected light of the cutting water is located at the center of the width of the cutting groove, and the reflected light of the cutting water Is determined that the cutting blade is not cut perpendicularly to the workpiece when the cutting groove is not located in the center of the width of the cutting groove,
A cutting blade cutting confirmation method characterized by the above.

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