JP2019181621A - Cutting method for workpiece - Google Patents

Abstract

To provide a workpiece cutting method capable of efficiently restraining occurrence of burrs in a die attachment film while preventing generation of processing failure in a workpiece.SOLUTION: A workpiece cutting method includes cutting by a cutting blade, a platy workpiece in which devices are formed respectively on the surface side areas partitioned by plural division-scheduled lines formed like lattice. The method comprises: a step of sticking a die attachment film of the laminate tape in which the die attachment film and dicing tape are laminated to the rear face of the workpiece and further sticking a periphery of the dicing tape to an annular frame to form a frame unit; a step of holding the workpiece on a chuck table of a cutting unit via the laminate tape; a step of forming a cutting groove for cutting the workpiece by down-cutting along the division-scheduled line; and a step of cutting by the cutting blade, the die attachment film exposed on the bottom of the cutting groove by up-cutting.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a workpiece cutting method for cutting a plate-like workpiece with a cutting blade.

  By dividing a plate-like workpiece made of a semiconductor wafer or glass substrate on which a plurality of devices typified by IC (Integrated Circuit) etc. are formed on the surface side along the planned dividing line (street), the device Can be obtained. This division of the workpiece is performed using, for example, a cutting device equipped with an annular cutting blade for cutting the workpiece. The workpiece is cut and divided by rotating the cutting blade and cutting the workpiece along the division line.

  In many cases, an adhesive layer for die bonding called a die attach film is attached to each device chip. Regarding the attachment of the die attach film, first, after attaching the die attach film covering the entire back surface of the work piece to the work piece before the division, the work piece is attached to the die attachment film along the line to be divided. A technique for obtaining a plurality of device chips having die attach films attached thereto by dividing them is known.

  Since the die attach film is formed of a flexible resin or the like, when the die attach film is cut by the cutting blade, the die attach film is stretched by the cutting blade, and a hook-shaped protrusion (burr) is generated. Since this burr can be an obstacle when die-bonding a device chip, various proposals have been made for suppressing the burr. For example, Patent Document 1 discloses a method of shrinking burrs by cutting a die attach film with a cutting blade and then subjecting the die attach film to a heat treatment.

JP 2004-79597 A

  As described above, when the flexible die attach film is attached to the back side of the workpiece, the workpiece is supported by the flexible member. If the work piece and the die attach film are simultaneously cut with a cutting blade in this state, a work defect such as chipping or cracking called chipping may occur in the work piece.

  As for burrs generated when the die attach film is cut with a cutting blade, a method of shrinking burrs by heating as described above has been proposed. However, in this method, in order to remove burrs, a heat treatment step that is independent from the division of the workpiece is necessary, and the production efficiency of the device chip is lowered.

  The present invention has been made in view of such problems, and cutting of a workpiece capable of efficiently suppressing the occurrence of burrs in a die attach film while preventing the occurrence of processing defects in the workpiece. It is an object to provide a method.

  According to the present invention, a cutting method for a workpiece, in which a plate-like workpiece in which devices are respectively formed in a region on a surface side defined by a plurality of division lines formed in a lattice shape is cut with a cutting blade. The die attach film of the laminated tape in which the die attach film and the dicing tape are laminated is attached to the back surface of the workpiece, and the outer peripheral portion of the dicing tape is attached to the annular frame. A frame unit forming step for forming a unit, a holding step for holding the workpiece on a chuck table of a cutting device via the laminated tape, and the chuck table and the cutting blade to rotate the cutting blade. The cutting blade is moved relative to each other so that the moving direction of the lower end coincides with the moving direction of the chuck table. After performing the first cutting step, the first cutting step for forming a cutting groove along the line to be cut to leave the die attach film and cut the workpiece by cutting the workpiece. The chuck table and the cutting blade are moved relative to each other so that the lower end of the rotating cutting blade moves and the moving direction of the chuck table is opposite, and exposed at the bottom of the cutting groove. A second cutting step of cutting the die attach film with the cutting blade is provided.

  In the method for cutting a workpiece according to the present invention, the depth that the cutting blade cuts into the die attach film in the first cutting step may be 5 μm or less.

  In the method of cutting a workpiece according to the present invention, the workpiece attached on the die attach film is cut by down-cutting, and then the die attach film is cut by up-cutting. Thereby, while preventing the processing defect (chipping, a crack, etc.) of a workpiece, generation | occurrence | production of the burr | flash of a die attach film can be suppressed efficiently.

It is a perspective view which shows the structural example of a frame unit. It is a partial cross section side view which shows the state by which the to-be-processed object was hold | maintained with the chuck table of the cutting device. FIG. 3A is a partial cross-sectional side view showing how the cutting grooves are formed, and FIG. 3B is an enlarged view of the lower end portion of the cutting blade in the first cutting step. It is a partial cross section side view which shows the mode of the process feed in a 1st cutting step. FIG. 5A is a partial cross-sectional side view showing how the die attach film is cut, and FIG. 5B is an enlarged view of the lower end portion of the cutting blade in the second cutting step. It is a partial cross section side view which shows the mode of the process feed in a 2nd cutting step.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a perspective view illustrating a configuration example of a frame unit 11 in which a plate-like workpiece 13 according to the present embodiment is supported by an annular frame 19.

  The workpiece 13 is formed in a disk shape using a semiconductor wafer, a glass substrate, or the like, and includes a front surface 13a and a back surface 13b. The workpiece 13 is divided into a plurality of regions by a plurality of scheduled division lines (streets) 15 arranged in a lattice pattern, and devices 17 each composed of an IC or the like are provided on the surface 13a side of the plurality of regions. Is formed. By dividing the workpiece 13 along the scheduled division line 15, a plurality of device chips each including the device 17 can be obtained.

  The material, shape, structure, size, etc. of the workpiece 13 are not limited. For example, as the workpiece 13, a semiconductor substrate (silicon substrate, SiC substrate, GaAs substrate, InP substrate, GaN substrate, etc.), glass substrate, sapphire substrate, ceramic substrate, resin substrate, metal substrate, or the like can be used. Further, the type, quantity, shape, structure, size, arrangement, etc. of the device 17 are not limited.

  When the workpiece 13 is divided, first, the frame unit 11 in which the workpiece 13 is supported by the annular frame 19 is formed in order to hold the workpiece 13 by the chuck table of the machining apparatus (frame unit formation). Step).

  As shown in FIG. 1, the workpiece 13 is supported by the annular frame 19 via a laminated tape 21 in which a circular die attach film 23 and a circular dicing tape 25 are laminated. The laminated tape 21 is configured by adhering a flexible die attach film 23 on a dicing tape 25, and the die attach film 23 has a diameter equal to or larger than the diameter of the workpiece 13 and equal to or smaller than the diameter of the dicing tape 25. It is formed as follows.

  The die attach film 23 of the laminated tape 21 is attached to the back surface 13 b of the workpiece 13, and the outer peripheral portion of the dicing tape 25 is attached to the annular frame 19. Thereby, the frame unit 11 in which the workpiece 13 is supported by the annular frame 19 is obtained.

  The material for the die attach film 23 and the dicing tape 25 is not limited. For example, the die attach film 23 can be formed of acrylic and epoxy resin, and the dicing tape 25 can be formed of a resin such as polyolefin or vinyl chloride.

  Next, the workpiece 13 supported by the annular frame 19 is held by the chuck table of the cutting device via the laminated tape 21 (holding step). FIG. 2 is a partial cross-sectional side view showing a state in which the workpiece 13 is held by the chuck table 4 of the cutting device 2.

  The cutting device 2 includes a chuck table 4 that sucks and holds the workpiece 13 and a clamp 8 that fixes an annular frame 19 that supports the workpiece 13. The workpiece 13 is disposed on the chuck table 4 via the laminated tape 21, and the annular frame 19 is fixed by the clamp 8. A part of the upper surface of the chuck table 4 constitutes a holding surface 4 a for sucking and holding the workpiece 13 via the laminated tape 21, and the holding surface 4 a is a suction path (not shown) formed inside the chuck table 4. ) Etc., and connected to a suction source (not shown).

  A processing feed mechanism (not shown) is provided below the chuck table 4. This machining feed mechanism has a function of moving the chuck table 4 in a machining feed direction (first horizontal direction) substantially parallel to the holding surface 4a. Instead of the chuck table 4, a chuck table that holds the workpiece 13 by a mechanical method, an electrical method, or the like may be used.

  Further, the cutting device 2 includes a cutting unit 6 for cutting the workpiece 13 above the chuck table 4. The cutting unit 6 includes a spindle 10 having an axial center in a direction substantially parallel to the holding surface 4a, and an annular cutting blade 12 is attached to the tip of the spindle 10. The spindle 10 is connected to a rotational drive source (not shown) such as a motor, and the cutting blade 12 mounted on the spindle 10 is rotated by a force transmitted from the rotational drive source. The cutting blade 12 is constituted by, for example, an electroformed grindstone in which diamond abrasive grains are fixed by nickel plating.

  The cutting unit 6 is supported by an elevating mechanism (not shown) and an index feed mechanism (not shown). The lifting mechanism has a function of moving (raising and lowering) the cutting unit 6 in the cutting and feeding direction (vertical direction), and the indexing feeding mechanism is substantially parallel to the holding surface 4a and generally in the machining feeding direction (first horizontal direction). It has a function of moving in the vertical index feed direction (second horizontal direction).

  In the holding step, the workpiece 13 is placed on the holding surface 4 a of the chuck table 4 via the laminated tape 21, and the negative pressure of the suction source is applied to the holding surface 4 a with the annular frame 19 fixed by the clamp 8. Let Thus, the workpiece 13 is held by the chuck table 4 via the laminated tape 21 with the surface 13a side exposed upward.

  Next, the cutting blade 12 is cut into the workpiece 13, thereby forming a cutting groove 27 that cuts the workpiece 13 while leaving the die attach film 23 along the planned dividing line 15 (first cutting step). ). FIG. 3A is a partial cross-sectional side view showing how the cutting groove 27 is formed in the first cutting step.

  In the first cutting step, the chuck table 4 is moved in a direction substantially parallel to the holding surface 4a and substantially perpendicular to the axis of the spindle 8 while rotating the cutting blade 12 into the workpiece 13. Perform machining feed. Thereby, a linear cutting groove 27 for cutting the workpiece 13 is formed.

  The height in the vertical direction of the cutting blade 12 in the first cutting step is set so that the workpiece 13 is cut and the die attach film 23 is not cut. FIG. 3B is an enlarged view of the lower end portion of the cutting blade 12 in the first cutting step. As shown in FIG. 3B, the cutting blade 12 is positioned so that the lower end thereof is substantially the same height as the back surface 13 b of the workpiece 13.

  In this state, the cutting blade 12 cuts the workpiece 13 without cutting the die attach film 23 by performing processing feed that relatively moves the chuck table 4 and the cutting blade 12. As a result, the die attach film 23 is exposed at the bottom of the cutting groove 27 formed by the cutting blade 12.

  Thus, in the first cutting step, the height of the cutting blade 12 is set so that the cutting blade 12 does not cut into the die attach film 23, and only the workpiece 13 is cut by the cutting blade 12. Thereby, generation | occurrence | production of the processing defect of the to-be-processed object 13 which may arise when the to-be-processed object 13 and the die attach film 23 are cut | disconnected simultaneously (chipping, a crack, etc. by the back surface 13b side) can be avoided.

  The height of the cutting blade 12 may be set so that the cutting blade 12 slightly cuts into the die attach film 23. If the cutting depth of the cutting blade 12 into the die attach film 23 is less than the thickness of the die attach film 23, the die attach film 23 remains without being cut. However, when the depth at which the cutting blade 12 is cut into the die attach film 23 is increased, processing defects are likely to occur. Therefore, the cutting depth is preferably set to 5 μm or less, for example.

  Further, in the first cutting step, a machining feed is performed in which the chuck table 4 and the cutting blade 12 are relatively moved so that the moving direction of the chuck table 4 coincides with the moving direction of the lower end of the rotating cutting blade 12. .

  FIG. 4 is a partial cross-sectional side view showing a state of processing feed in the first cutting step. As shown in FIG. 4, the chuck table 4 is moved in the machining feed direction indicated by arrow B while the cutting blade 12 is rotated in the direction indicated by arrow A. As a result, a so-called downcut is performed in which the cutting blade 12 cuts the workpiece 13 from the front surface 13 a side to the back surface 13 b side of the workpiece 13.

  When cutting the workpiece 13 whose front surface 13a is exposed and whose back surface 13b is supported by a support member (die attach film 23 in FIG. 4), the cutting blade 12 is processed from the back surface 13b side to the front surface 13a side. When so-called up-cutting for cutting the object 13 is performed, chipping is likely to occur on the surface 13a side. On the other hand, when the workpiece 13b is cut by down-cutting, the occurrence of chipping tends to be suppressed by the support member that supports the back surface 13b side.

  Therefore, in the present embodiment, the workpiece 13 is cut by down-cutting. Thereby, generation | occurrence | production of the chipping at the time of the division | segmentation of the workpiece 13 can be suppressed.

  As described above, in the first cutting step, the workpiece 13 is cut by down-cutting under the condition that the cutting blade 12 does not cut into the die attach film 23 or the cutting amount becomes small. Thereby, generation | occurrence | production of the processing defect by the cutting | disconnection of the to-be-processed object 13 can be suppressed.

  Next, the die attach film 23 exposed at the bottom of the cutting groove 27 formed in the first cutting step is cut with the cutting blade 12 (second cutting step). FIG. 5A is a partial cross-sectional side view showing a state where the die attach film 23 is cut in the second cutting step.

  In the second cutting step, while the cutting blade 12 is rotated and cut into the die attach film 23 exposed at the bottom of the cutting groove 27, the chuck table 4 is substantially parallel to the holding surface 4 a and substantially perpendicular to the axis of the spindle 8. Machining feed to move in any direction. Thereby, the die attach film 23 is cut along the cutting groove 27.

  The height in the vertical direction of the cutting blade 12 in the second cutting step is set so that the die attach film 23 is cut. FIG. 5B is an enlarged view of the lower end portion of the cutting blade 12 in the second cutting step. 5B, the lower end of the cutting blade 12 is disposed below the lower surface of the die attach film 23, and is positioned so that the entire thickness direction of the die attach film 23 can be cut.

  By cutting and feeding in this state, the cutting blade 12 cuts the die attach film 23 along the cutting groove 27. However, in the second cutting step, unlike the first cutting step, the chuck table 4 and the cutting blade 12 are moved so that the lower end of the rotating cutting blade 12 moves in the opposite direction to the moving direction of the chuck table 4. Move relative.

  FIG. 6 is a partial cross-sectional side view showing a state of processing feed in the second cutting step. As shown in FIG. 6, the chuck table 4 is moved in the machining feed direction indicated by the arrow C while the cutting blade 12 is rotated in the direction indicated by the arrow A. Thereby, the upcut which the cutting blade 12 cuts the die attach film 23 toward the upper surface side from a lower surface side is performed.

  When the die attach film 23 is cut by the cutting blade 12, the die attach film 23 may be stretched by the cutting blade 12, and a bowl-shaped protrusion (burr) may be generated. Since this burr can be an obstacle when die-bonding a device chip obtained by dividing the workpiece 13, it is preferable not to generate it as much as possible.

  As shown in FIG. 6, the die attach film 23 is cut when the upper surface side of the die attach film 23 is covered with the workpiece 13 and the lower surface side is covered with a dicing tape 25 that is more flexible than the workpiece 13. If it carries out by a down cut similarly to a 1st cutting step, the die attach film 23 will be cut toward the more flexible dicing tape 25 side. When the cutting blade 12 cuts the die attach film 23 toward the flexible layer in this way, burrs of the die attach film 23 tend to occur.

  Therefore, in this embodiment, the die attach film 23 is cut by up-cutting, and the die attach film 23 is cut toward the workpiece 13 having higher rigidity than the dicing tape 25. Thereby, generation | occurrence | production of the burr | flash by the cutting | disconnection of the die attach film 23 is suppressed.

  Further, the first cutting step and the second cutting step can be continuously performed in the forward path and the return path of the machining feed, respectively. Specifically, first, the workpiece 13 is cut by a down cut by moving the chuck table 4 in the first machining feed direction indicated by the arrow B (FIG. 4) (outward path). After that, the chuck table is moved in the direction opposite to the second machining feed direction indicated by the arrow C (FIG. 6), that is, the first machining feed direction without changing the rotation direction of the cutting blade 12 (return path). The touch film 23 is cut by up-cutting.

  As described above, the second cutting step of cutting the die attach film 23 by up-cutting can be continuously performed by changing the moving direction of the chuck table 4 after the first cutting step. Therefore, generation | occurrence | production of the burr | flash of the die attach film 23 can be suppressed efficiently, without adding new independent processes, such as heat processing.

  Furthermore, the second cutting step can be performed without moving the spindle 10 of the cutting unit 6 in the indexing and feeding direction after the first cutting step. Therefore, the position of the cutting region of the cutting blade 12 does not shift between the first cutting step and the second cutting step, and the workpiece 13 can be prevented from being cut by up-cutting in the second cutting step. Thereby, it can avoid that chipping generate | occur | produces in the surface 13a side of the to-be-processed object 13. FIG.

  When the first cutting step and the second cutting step are performed on all the division lines 15, the workpiece 13 is divided into a plurality of device chips each having a device 17 and having a die attach film attached thereto. As a result, a high-quality device chip in which processing defects (such as chipping and cracks) and burrs on the die attach film are suppressed can be obtained.

  Table 1 shows the results of cutting the workpiece 13 and the die attach film 23 by the first cutting step and the second cutting step. Table 1 shows that the depth at which the cutting blade 12 cuts into the die attach film 23 in the first cutting step is set to −5 μm, 0 μm, 5 μm, and 10 μm, and chipping of the obtained device chip and generation of burrs on the die attach film 23 are shown. This indicates the presence or absence of. The die attach film 23 having a thickness of 30 μm was used.

  The cutting depth of −5 μm is a condition in which the lower end of the cutting blade 12 is positioned 5 μm above the back surface 13b of the workpiece 13. The cutting depth of 0 μm is a condition in which the cutting blade 12 is positioned so that the lower end of the cutting blade 12 and the back surface 13b of the workpiece 13 are at the same height, and the cutting blade 12 is not cut into the die attach film 23. It is.

  From Table 1, when the cutting depth is -5 μm, that is, when the first cutting step is performed under the condition that a part of the back surface side 13b of the workpiece 13 is not cut and the workpiece 13 is not completely cut, It can be seen that chipping occurs in the device chip. Therefore, it is preferable that the cutting depth is 0 μm or more so that at least the workpiece 13 can be cut in the first cutting step.

  It can be seen that when the depth of cut is not less than 0 μm and not more than 5 μm, chipping of the device chip does not occur and good results are obtained. On the other hand, when the depth of cut reached 10 μm, a result of chipping in the device chip was obtained. Therefore, the cutting depth of the cutting blade 12 into the die attach film 23 in the first cutting step is particularly preferably 5 μm or less. However, if the occurrence frequency of chipping is below a certain level, the first cutting step may be performed with the cutting depth set to be larger than 5 μm.

  Moreover, no burr | flash of the die attach film 23 was observed even if the cutting depth was any value. Therefore, even if the die attach film 23 is cut to some extent in the first cutting step, it can be seen that generation of burrs can be prevented by cutting the die attach film 23 by up-cutting in the second cutting step.

  As mentioned above, in the processing method of the workpiece which concerns on this embodiment, after cut | disconnecting the workpiece 13 stuck on the die attach film 23 by a down cut, the die attach film 23 is cut | disconnected by an up cut. . Thereby, while preventing the processing defect (chipping, a crack, etc.) of the to-be-processed object 13, generation | occurrence | production of the burr | flash of the die attach film 23 can be suppressed efficiently.

  In addition, the structure, method, and the like according to the above-described embodiment can be appropriately modified and implemented without departing from the scope of the object of the present invention.

DESCRIPTION OF SYMBOLS 11 Frame unit 13 Work piece 13a Front surface 13b Back surface 15 Scheduled division line 17 Device 19 Ring frame 21 Laminated tape 23 Die attach film 25 Dicing tape 27 Cutting groove 2 Cutting device 4 Chuck table 4a Holding surface 6 Cutting unit 8 Clamp 10 Spindle 12 Cutting blade

Claims (2)

A cutting method for a workpiece, in which a plate-like workpiece having a device formed on each surface-side region defined by a plurality of division lines formed in a lattice shape is cut with a cutting blade,
The die attach film of the laminated tape in which the die attach film and the dicing tape are laminated is attached to the back surface of the workpiece, and the outer peripheral portion of the dicing tape is attached to the annular frame to form a frame unit. A frame unit forming step;
A holding step of holding the workpiece on a chuck table of a cutting device via the laminated tape;
The chuck table and the cutting blade are relatively moved so that the moving direction of the chuck table coincides with the moving direction of the lower end of the rotating cutting blade, and the cutting blade is cut into the workpiece. A first cutting step for forming a cutting groove for cutting the workpiece while leaving the die attach film along the line to be divided,
After performing the first cutting step, the chuck table and the cutting blade are relatively moved so that the lower end of the rotating cutting blade moves and the moving direction of the chuck table is opposite. And a second cutting step of cutting the die attach film exposed at the bottom of the cutting groove with the cutting blade.   The method for cutting a workpiece according to claim 1, wherein in the first cutting step, a depth that the cutting blade cuts into the die attach film is 5 μm or less.