JP2004356357A - Cutting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting method by which the generation of cracking can be prevented even if a workpiece is formed of brittle member. <P>SOLUTION: The cutting method is used to cut a workpiece that is held on a chuck table 3 and is formed of brittle material, into chips like a grid by cutting blade. In this case, when the workpiece is held on the chuck table 3, a placement surface for placing the workpiece is made even and smooth, and a workpiece holding plate 31 with a plurality of suction holes 314 open to the placement surface is interposed on the chuck table 3. The workpiece held on the upper surface of a dicing tape that is attached to a circular frame is placed on the placement surface of the plate 31 with the dicing tape in between. Then, while the workpiece is sucked by the suction holes 314 and is held on the placement surface of the plate 31, it is cut into chips like a grid by the cutting blade. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a cutting method for cutting a workpiece made of a brittle material, such as a semiconductor wafer or a lithium tantalate substrate, into a grid by a cutting blade and dividing the work into individual chips.
[0002]
[Prior art]
As is well known to those skilled in the art, in a semiconductor device manufacturing process, a plurality of regions are partitioned by lines to be cut (streets) arranged in a grid on the surface of a substantially disk-shaped semiconductor wafer, and the plurality of regions are partitioned. A circuit such as an IC or an LSI is formed in the region. Then, the semiconductor wafer is cut along the streets to separate the region where the circuit is formed, thereby manufacturing individual semiconductor chips. Cutting along the streets of a semiconductor wafer is usually performed by a cutting device called a dicer. The cutting apparatus includes a chuck table as a workpiece holding unit that holds a semiconductor wafer that is a workpiece, and a cutting unit that includes a cutting blade that cuts the semiconductor wafer held by the chuck table. I have. The cutting blade has a disk-shaped base and an annular cutting edge mounted on the outer peripheral portion of the side surface of the base. The cutting edge is, for example, a diamond abrasive having a particle size of about 3 μm fixed to the base by electroforming. It is formed to a thickness of about 20 μm.
[0003]
However, a semiconductor wafer formed of silicon or a compound semiconductor wafer, a silicon carbide substrate, a lithium tantalate substrate, a quartz substrate, etc. are wafers formed of a brittle material, and are cut into a lattice shape by a cutting blade and cut into individual chips. When divided, chipping occurs particularly on the rear surface side, which causes a problem of deteriorating the quality of a semiconductor chip or the like. That is, as shown in FIG. 8, when the workpiece W is cut in a lattice shape by a cutting blade, a chip T occurs at the intersection of the cutting grooves G. The present inventors examined a chip obtained by cutting a lithium tantalate substrate into a lattice shape and dividing the chip into individual pieces. As a result, the chipping rate was about 80% or more, and the chipping size (A × B) was on average. (15 μm × 30 μm).
[0004]
[Problems to be solved by the invention]
The present inventors have examined the cause of the occurrence of the chipping and found that the cause was caused by the method of holding the workpiece. That is, in a chuck table generally used as holding means for holding a workpiece, a support member having a mounting surface on which the workpiece is mounted is formed of porous ceramics. This porous ceramic has a porosity of about 40% and its surface is not formed as a smooth surface. As a result, when the work held on the support member made of porous ceramics is cut by the cutting blade, it is considered that the work is distorted and chipped.
[0005]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and a main technical problem thereof is to provide a cutting method capable of suppressing occurrence of chipping even when a workpiece is formed of a brittle material.
[0006]
[Means for Solving the Problems]
According to the present invention, there is provided a cutting method for cutting a workpiece made of a brittle material held on a chuck table in a lattice shape by a cutting blade and dividing the chip into individual chips.
When the work piece is held on the chuck table, the work piece on which the work piece is placed is formed as a smooth surface and a plurality of suction holes are formed in the placement face. A workpiece holding plate is interposed on the chuck table, and the workpiece supported on the upper surface of a dicing tape mounted on an annular frame on the mounting surface of the workpiece holding plate is removed from the dicing tape. The workpiece is cut into a lattice shape by the cutting blade in a state where the workpiece is suction-held on the mounting surface of the workpiece holding plate through the suction hole.
A cutting method is provided.
[0007]
The chuck table includes a support member formed of porous ceramics and having a support surface, and the workpiece holding plate is mounted on the support surface of the support member. In the workpiece holding plate, a plurality of first cutting grooves are formed in parallel on one surface, and a plurality of first cutting grooves intersecting with the first cutting groove and reaching the first cutting groove on the other surface. A second cutting groove is formed in parallel, and a suction hole is formed at an intersection of the first cutting groove and the second cutting groove. The workpiece holding plate is made of a silicon plate.
[0008]
Further, according to the present invention, there is provided a cutting method in which a workpiece made of a brittle material held on a chuck table is cut into a lattice shape by a cutting blade and divided into individual chips,
The chuck table includes a workpiece holding member having a smooth mounting surface on which the workpiece is mounted, and a plurality of suction holes formed in the mounting surface. The workpiece supported on the upper surface of a dicing tape mounted on an annular frame on the mounting surface of the workpiece holding member is placed via the dicing tape, and the workpiece is passed through the suction hole. In a state where the workpiece is held by suction on the mounting surface of the workpiece holding member, the workpiece is cut into a lattice shape by the cutting blade,
A cutting method is provided.
[0009]
It is desirable that the side of the dicing tape that comes into contact with the mounting surface be easily peeled off from the mounting surface.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of a cutting method according to the present invention will be described in detail with reference to the accompanying drawings.
[0011]
FIG. 1 shows a perspective view of a cutting device for performing a cutting method according to the present invention.
The cutting device in the illustrated embodiment includes a substantially rectangular parallelepiped device housing 2. In the apparatus housing 2, a chuck table 3 as work holding means for holding a work is provided so as to be movable in a cutting feed direction indicated by an arrow X. The chuck table 3 will be described with reference to FIG. The chuck table 3 shown in FIG. 2 includes a support table 31 and a support member 32 mounted on an upper end of the support table 31. The support base 31 is formed of a metal material such as stainless steel, and has a circular fitting hole 311 having an open top at its upper end. A circular suction groove 312 is formed at the center of the bottom surface of the fitting hole 311, and an annular suction groove 313 is formed outside the suction groove 312. Further, a suction passage 314 communicating with the suction grooves 312 and 313 is formed in the support base 31, and the suction hole 314 is connected to a suction unit (not shown). The support member 32 is formed in a circular shape from porous ceramics, and is fitted into the fitting hole 311. The chuck table 3 configured as described above is configured to be rotatable by a rotation mechanism (not shown). A workpiece holding plate 33 is placed on a support surface, which is an upper surface of a support member 32 constituting the chuck table 3.
[0012]
In the illustrated embodiment, the workpiece holding plate 33 is formed of a circular silicon plate having a thickness of 0.5 to 1.0 mm as shown in FIG. On one surface 33a side of the workpiece holding plate 33, a plurality of first grooves 331 having a depth of about half the thickness of the workpiece holding plate 33 as shown in FIGS. Are formed in parallel. Further, on the other surface 33b side of the workpiece holding plate 33, as shown in FIGS. 3 and 4, a plurality of depths having a depth reaching the first groove 331 in a direction intersecting the first groove 331 are provided. The second groove 332 is formed in parallel. The first groove 331 and the second groove 332 are each formed in a width of 20 μm and at an interval of 3 mm in the illustrated embodiment. Therefore, a square communication hole (suction hole) 333 having a side of 20 μm is formed at a portion where the first groove 331 and the second groove 332 intersect. Therefore, one surface 33 a and the other surface 33 b of the workpiece holding plate 33 are communicated with the communication hole (suction hole) 333 by the first groove 331 and the second groove 332. In the illustrated embodiment, the workpiece holding plate 33 configured as described above has one surface 33a formed as a smooth surface, and the one surface 33a formed on the smooth surface mounts the workpiece. It is the mounting surface on which to place. The workpiece holding plate 33 configured as described above has the other surface 33b placed on the support member 33 formed of the porous ceramic. Accordingly, the communication hole (suction hole) 333 formed in the workpiece holding plate 33 communicates with the first groove 331 opened on the one surface 33a serving as the mounting surface, and also communicates with the second groove 332 and the porous surface. The support member 32 made of ceramics, the fitting hole 311, the suction grooves 312 and 313, and the suction passage 314 communicate with suction means (not shown). The work piece is placed on the placement surface, which is one surface 33a of the work piece holding plate 33 configured as described above, and the suction means (not shown) is actuated. The workpiece can be suction-held on the surface 33a.
[0013]
Returning to FIG. 1, the explanation of 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 which is an indexing direction and a direction indicated by an arrow Z which is a cutting direction. It comprises a rotating spindle 42 supported and a cutting blade 43 mounted on the front end of the rotating spindle 42. In the illustrated embodiment, the cutting blade 43 fixes, for example, a diamond abrasive having a particle size of about 2 to 4 μm to a thickness of about 20 μm on a side surface of a disk-shaped base made of aluminum by nickel plating, and forms an outer peripheral portion of the base. It is composed of an electroformed blade formed in a circular shape with a cutting edge of 2 to 3 mm protruding after being removed by etching. Further, the cutting device in the illustrated embodiment captures an image of the surface of the workpiece held on the support member 32 constituting the chuck table 3 and detects an area to be cut by the cutting blade 43, An imaging mechanism 6 for checking the state of the groove is provided. The imaging mechanism 6 is composed of optical means such as a microscope and a CCD camera. Further, the cutting device includes a display unit 7 that displays an image captured by the imaging mechanism 6.
[0014]
The cutting device in the illustrated embodiment includes a cassette 14 for stocking a workpiece. Here, the workpiece will be described with reference to FIG. The workpiece 11 is adhered and supported on an upper surface of a dicing tape 13 mounted on an annular support frame 12 formed of a metal material such as stainless steel. The lower surface of the dicing tape 13 is formed easily from the mounting surface, and is preferably formed, for example, on a rough surface. The workpiece 11 thus supported by the support frame 12 via the dicing tape 13 is accommodated in the cassette 14. Note that the cassette 14 is mounted on a cassette table 141 that is vertically movably arranged by a lifting means (not shown).
[0015]
The cutting device in the illustrated embodiment is a workpiece unloading unit that unloads the workpiece 11 (supported by the support frame 12 via the tape 13) from the cassette 14 to the workpiece mounting area 15. 16, a workpiece transfer means 17 for transferring the workpiece 11 unloaded by the workpiece unloading means 16 onto the chuck table 3, and cleaning the workpiece 11 cut on the chuck table 3. The cleaning unit 18 includes a cleaning unit 18 for cleaning the workpiece 11 cut on the chuck table 3 and a cleaning / conveying unit 19 for conveying the workpiece 11 to the cleaning unit 18.
[0016]
The cutting device in the illustrated embodiment is configured as described above, and its operation will be described below. In performing the cutting operation, the workpiece holding plate 33 is placed on a support member 33 formed of porous ceramics constituting the chuck table 3.
The workpiece 11 accommodated in a predetermined position of the cassette 14 (the workpiece 11 supported by the support frame 12 by the tape 13 is simply referred to as the workpiece 11) is moved up and down by a raising / lowering means (not shown). By moving, it is positioned at the carry-out position. Next, the workpiece unloading means 16 moves forward and backward to unload the workpiece 11 positioned at the unloading position to the workpiece mounting area 15. The workpiece 11 carried out to the workpiece mounting area 15 is one surface 33a of the workpiece holding plate 33 placed on the chuck table 3 by the turning operation of the workpiece transport means 17. It is conveyed onto the mounting surface, and is suction-held by the workpiece holding plate 33 by the suction action of a suction means (not shown). The chuck table 3 that has thus suction-held the workpiece 11 via the workpiece holding plate 33 is moved to a position immediately below the imaging mechanism 6. When the chuck table 3 is positioned directly below the imaging mechanism 6, the streets 11a and 11b formed on the workpiece 11 are detected by the imaging mechanism 6, and the spindle unit 4 is moved and adjusted in the direction of the arrow Y which is the indexing direction. A precise alignment operation between the street and the cutting blade 43 is performed.
[0017]
Thereafter, while the cutting blade 43 is cut by a predetermined amount in the direction indicated by the arrow Z and is rotated in the predetermined direction, the chuck table 3 holding the workpiece 11 by suction is held in the direction indicated by the arrow X which is the cutting feed direction (the cutting blade). The workpiece 11 held on the chuck table 3 via the workpiece holding plate 33 is moved in the first direction by the cutting blade 43 in a direction perpendicular to the rotation axis of the workpiece 43. Is cut along the street. When all the streets 11a in the first direction formed on the workpiece 11 are cut, the chuck table 3 holding the workpiece 11 by suction is rotated by 90 degrees, and the street 11a in the first direction is rotated. By executing the cutting operation along the street 11b in the second direction in the same manner as the cutting, all the streets formed in a grid on the workpiece 11 are cut and divided into individual chips. The divided semiconductor chips do not fall apart due to the action of the dicing tape 13, and the state of the workpiece 11 supported by the frame 12 is maintained.
[0018]
Here, the holding state of the workpiece 11 during the above cutting will be described. As described above, the surface 33a (mounting surface) of the workpiece holding plate 33 interposed between the chuck table 3 and the workpiece 11 is formed as a smooth surface. The workpiece 11 sucked and held on one surface 33a (mounting surface) is supported on a smooth surface via a dicing tape 13. Therefore, even if a cutting force is applied by the cutting blade 43, the workpiece 11 is not distorted, so that chipping is suppressed. The present inventors conducted a test in which a lithium tantalate substrate was held as a workpiece using the workpiece holding plate 33 described above, and cut into a grid by the cutting blade 43 as described above, and divided into individual chips. Was done. When the chips thus divided were examined, the chipping rate was 20% or less, and the chipping size (A × B) was (4 μm × 12 μm) on average. In this way, by supporting the workpiece on a smooth surface, the occurrence rate of chipping can be significantly reduced, and the chipping rate can be significantly reduced, as compared with the conventional supporting method using a suction chuck formed of porous ceramics. The size can also be significantly reduced.
[0019]
In the above-described embodiment, the configuration in which the workpiece holding plate 33 is placed on the support member 32 formed of porous ceramics has been described. However, the support member 32 is removed, and the workpiece holding plate 33 is removed. It may be configured to directly fit into the fitting hole 311 formed in the support base body 31 constituting the suction chuck support base 30.
[0020]
When the cutting of the workpiece 11 is completed as described above, the chuck table 3 holding the workpiece 11 via the workpiece holding plate 33 is returned to the position where the workpiece 11 is first suction-held, and Then, the suction action of the suction means (not shown) is cut off, and the suction holding of the workpiece 11 is released. Next, the workpiece 11 is held by the cleaning / conveying means 19 and conveyed to the cleaning means 18. The lower surface of the dicing tape 13 is easily formed from the mounting surface, and is formed, for example, on a rough surface. Therefore, even if the mounting surface, which is one surface 33a of the workpiece holding plate 33, is formed as a smooth surface, it is easily peeled off. The workpiece 11 transported to the cleaning means 18 is cleaned and dried here. The workpiece 11 thus cleaned and dried is carried out to the workpiece mounting area 15 by the workpiece transporting means 17. Then, the workpiece 11 is stored in a predetermined position of the cassette 14 by the workpiece discharging means 16.
[0021]
Next, an embodiment of the present invention will be described with reference to FIGS.
The chuck table 8 in the embodiment shown in FIGS. 6 and 7 includes a support 81 and a workpiece holding member 82 mounted on the support 81. The support base 81 is formed of a metal material such as stainless steel, and has a circular fitting hole 811 having an open top at the upper end. A step portion 812 projecting from the bottom surface is formed on the inner periphery of the fitting hole 811. In addition, a suction passage 813 that opens at the bottom of the fitting hole 811 is formed in the support base 81, and the suction passage 813 is connected to a suction unit that is desired to be illustrated. The workpiece holding member 82 is formed in a disk shape from a metal material such as stainless steel, and has a plurality of suction holes 821 opened on one surface 82a and the other surface 82b. The suction holes 821 have a diameter of 20 to 100 μm and are formed at intervals of 3 to 10 mm. One surface 82a of the workpiece holding member 82 is formed as a smooth surface, and the one surface 82a formed on the smooth surface serves as a mounting surface on which the workpiece is mounted. The workpiece holding member 82 thus configured is placed on the step portion 812 of the fitting hole 811 formed in the support base 81, and the outer peripheral surface is attached to the suction chuck support base 81 by a fixing means such as brazing. Fixed. In the chuck table 8 configured as described above, one surface 82a serving as the mounting surface of the workpiece holding member 82 is formed as a smooth surface, so that the chuck table 8 is mounted on the mounting surface of the workpiece holding member 82. By cutting the workpiece while holding it by suction, occurrence of chipping can be suppressed. When removing the workpiece 11 from the chuck table 8, it is desirable to supply water or a mixed fluid of water and air to the suction passage 813, and to eject the fluid from the suction hole 821.
[0022]
【The invention's effect】
According to the present invention, when the workpiece is held on the chuck table, the mounting surface on which the workpiece is mounted is formed as a smooth surface and the plurality of suction holes are opened in the mounting surface. Since the workpiece holding plate on which is formed is interposed on the chuck table, the workpiece is supported on a smooth surface via the dicing tape. Therefore, even if a cutting force is applied by the cutting blade, the workpiece is not distorted. Therefore, even when the workpiece is formed of a brittle material, the occurrence of chipping on the rear surface, which is particularly likely to occur, can be suppressed. .
[0023]
Further, according to the present invention, since the mounting surface of the workpiece holding member constituting the chuck table for holding the workpiece is formed to be a smooth surface, the workpiece is smoothed through the dicing tape. It is supported by the surface. Therefore, even if a cutting force is applied by the cutting blade, the workpiece is not distorted. Therefore, even when the workpiece is formed of a brittle material, the occurrence of chipping on the rear surface, which is particularly likely to occur, can be suppressed. .
[Brief description of the drawings]
FIG. 1 is a perspective view of a cutting device for performing a cutting method according to the present invention.
FIG. 2 is a sectional view showing one embodiment of a chuck table and a workpiece holding plate provided in the cutting device shown in FIG. 1;
FIG. 3 is a perspective view of a workpiece holding plate shown in FIG. 2;
FIG. 4 is an enlarged sectional view of the workpiece holding plate shown in FIG. 3;
FIG. 5 is a perspective view showing a state in which a workpiece is supported on a dicing tape mounted on a frame.
FIG. 6 is a sectional view showing another embodiment of the chuck table provided in the cutting device.
FIG. 7 is a perspective view of the chuck table shown in FIG. 6;
FIG. 8 is an explanatory diagram showing an enlarged state of a cutting groove obtained by cutting a workpiece into a lattice shape.
[Explanation of symbols]
2: Device housing 3: Chuck table 31: Support table 31: Workpiece holding plate 4: Spindle unit 41: Spindle housing 42: Rotating spindle 43: Cutting blade 5: Imaging mechanism 6: Display means 8: Chuck table 81: Support Table 82: Workpiece holding member 11: Workpiece 12: Support frame 13: Dicing tape

Claims (7)

A cutting method in which a workpiece made of a brittle material held on a chuck table is cut into a lattice shape by a cutting blade and divided into individual chips,
When the work piece is held on the chuck table, the work piece on which the work piece is placed is formed as a smooth surface and a plurality of suction holes are formed in the placement face. A workpiece holding plate is interposed on the chuck table, and the workpiece supported on the upper surface of a dicing tape mounted on an annular frame on the mounting surface of the workpiece holding plate is removed from the dicing tape. The workpiece is cut into a lattice shape by the cutting blade in a state where the workpiece is suction-held on the mounting surface of the workpiece holding plate through the suction hole.
A cutting method characterized in that: The cutting method according to claim 1, wherein the chuck table includes a support member formed of porous ceramics and having a support surface, and the workpiece holding plate is placed on the support surface of the support member. In the workpiece holding plate, a plurality of first cutting grooves are formed in parallel on one surface, and a plurality of first cutting grooves intersecting the first cutting groove and reaching the first cutting groove on the other surface. 3. The cutting method according to claim 1, wherein the second cutting groove is formed in parallel, and a suction hole is formed at an intersection of the first cutting groove and the second cutting groove. 4. The cutting method according to claim 1, wherein the workpiece holding plate is made of a silicon plate. A cutting method in which a workpiece made of a brittle material held on a chuck table is cut into a lattice by a cutting blade and divided into individual chips,
The chuck table includes a workpiece holding member having a smooth mounting surface on which the workpiece is mounted, and a plurality of suction holes formed in the mounting surface. The workpiece supported on the upper surface of a dicing tape mounted on an annular frame on the mounting surface of the workpiece holding member is placed via the dicing tape, and the workpiece is passed through the suction hole. In a state where the workpiece is held by suction on the mounting surface of the workpiece holding member, the workpiece is cut into a lattice shape by the cutting blade,
A cutting method characterized in that: The cutting method according to any one of claims 1 to 5, wherein a side of the dicing tape that comes into contact with the mounting surface is formed easily from the mounting surface. The cutting method according to claim 6, wherein a side of the dicing tape that contacts the mounting surface is formed as a rough surface.

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