JP2021009968A - Device chip manufacturing method - Google Patents

Abstract

To provide a manufacturing method for a device chip capable of reducing the number of steps and costs.SOLUTION: A manufacturing method for a device chip which divides a work-piece where devices are formed on surface sides of a plurality of areas divided by a plurality of division schedule lines crossing each other into a plurality of device chips includes: a groove formation step which cuts a first cutting blade on a surface side of the work-piece and has depth equal to thickness of the device chip or thicker along the division schedule lines; an adhesive tape sticking step for sticking an adhesive tape on the surface side of the work-piece where the groove is formed; and a reverse surface cutting step for exposing the groove on the reverse surface side of the work-piece and dividing the work-piece into a plurality of device chips by cutting a second cutting blade thicker than the first cutting blade on the reverse surface side of the work-piece and cutting the whole reverse surface side of the work-piece so that thickness of the work-piece becomes the same as that of the device chip.SELECTED DRAWING: Figure 5

Description

The present invention relates to a method for manufacturing a device chip that divides a workpiece into a plurality of device chips.

Wafers in which devices such as ICs (Integrated Circuits) and LSIs (Large Scale Integration) are formed on the surface side of a plurality of regions partitioned by a plurality of scheduled division lines (streets) arranged in a grid pattern are scheduled to be divided. By dividing along the line, a plurality of device chips, each having a device, are manufactured. This device chip is mounted on various electronic devices such as mobile phones and personal computers.

In recent years, as electronic devices have become smaller and thinner, device chips are also required to be thinner. Therefore, before dividing the wafer, a process of thinning the wafer may be performed by performing a grinding process on the back surface side of the wafer. By thinning the wafer and then dividing it, a thin device chip can be obtained.

A process called DBG (Dicing Before Grinding) has been proposed as a method of thinning a wafer and dividing it into a plurality of device chips (see Patent Document 1). In the DBG process, first, a groove having a depth less than the thickness of the wafer is formed along the planned division line on the surface side of the wafer on which the device is formed (half cut). After that, the back surface side of the wafer is ground and the grooves are exposed on the back surface side of the wafer to divide the wafer into a plurality of device chips. By using this DBG process, it is possible to obtain effects such as suppressing the occurrence of chipping on the back surface side of the wafer.

Japanese Unexamined Patent Publication No. 2003-7653

In the DBG process, the wafer is half-cut using a cutting device that cuts the wafer with a cutting blade, and the wafer is thinned using a grinding device that grinds the wafer with a grinding wheel. Therefore, in the process of dividing the wafer into device chips, it is necessary to prepare and move at least two types of processing devices, which causes a problem that the number of processes and the cost increase.

The present invention has been made in view of such problems, and an object of the present invention is to provide a method for manufacturing a device chip capable of reducing the number of steps and costs.

According to one aspect of the present invention, a method for manufacturing a device chip for dividing a work piece in which a device is formed on the surface side of a plurality of regions partitioned by a plurality of scheduled division lines intersecting each other into a plurality of device chips. A groove forming step in which a first cutting blade is cut into the surface side of the workpiece to form a groove having a depth equal to or greater than the thickness of the device chip along the planned division line. An adhesive tape sticking step for sticking the adhesive tape to the front surface side of the workpiece in which the groove is formed, and a second cutting blade thicker than the first cutting blade on the back surface side of the workpiece. The groove is exposed on the back surface side of the work piece by making a cut and cutting the entire back surface side of the work piece so that the thickness of the work piece becomes the thickness of the device chip. Provided is a method for manufacturing a device chip comprising a back surface cutting step for dividing the workpiece into a plurality of the device chips.

Preferably, in the back surface cutting step, the holding table for holding the workpiece and the second cutting blade are moved in the moving direction of the lower end of the second cutting blade and the moving direction of the holding table. The second cutting blade is cut from the back surface side to the front surface side of the work piece by moving the second cutting blade relative to each other.

Further, preferably, in the back surface cutting step, the holding table for holding the workpiece on the holding surface and the second cutting blade are parallel to the holding surface and perpendicular to the rotation axis of the second cutting blade. The cutting step of cutting the workpiece with the second cutting blade and the holding table and the second cutting blade while relatively moving along the above directions of the second cutting blade. By repeating the cutting blade moving step of moving the cutting blade relative to the direction parallel to the rotation axis, the entire back surface side of the workpiece is cut.

Further, preferably, in the back surface cutting step, the holding table and the second holding table for holding the workpiece on the holding surface are rotated about a rotation axis along a direction perpendicular to the holding surface. By relatively moving the cutting blade of No. 1 along a direction parallel to the rotation axis of the second cutting blade, the back surface side of the work piece is cut in a spiral shape.

In the method for manufacturing a device chip according to one aspect of the present invention, the front surface side of the workpiece is cut by the first cutting blade to form a groove, and then the back surface side of the workpiece is cut by the second cutting blade. Then, the workpiece is divided into a plurality of device chips. Therefore, when the work piece is divided into a plurality of device chips, the step of grinding the work piece to be thinned by using a grinding device can be omitted. This eliminates the need for preparation and operation of the grinding apparatus, and can reduce the number of steps and costs required for manufacturing the device chip.

It is a perspective view which shows the cutting apparatus. It is a perspective view which shows the workpiece. FIG. 3A is a perspective view showing an workpiece in the groove forming step, and FIG. 3B is a cross-sectional view showing an workpiece in the groove forming step. FIG. 4A is a perspective view showing a work piece in the adhesive tape sticking step, and FIG. 4B is a cross-sectional view showing a work piece in the adhesive tape sticking step. FIG. 5 (A) is a perspective view showing a work piece in the back surface cutting step, and FIG. 5 (B) is a cross-sectional view showing a work piece in the back surface cutting step.

Hereinafter, the present embodiment will be described with reference to the accompanying drawings. First, a configuration example of a cutting device that can be used in the device chip manufacturing method according to the present embodiment will be described. FIG. 1 is a perspective view showing a cutting device 2.

The cutting device 2 includes a base 4 on which each component constituting the cutting device 2 is mounted. An X-axis moving mechanism 6 is provided on the upper surface 4a of the base 4. The X-axis moving mechanism 6 includes a pair of X-axis guide rails 8 arranged along the X-axis direction (machining feed direction, front-back direction), and the X-axis moving table 10 is attached to the X-axis guide rail 8 on the X-axis. It is mounted so that it can slide along the guide rail 8 in the X-axis direction.

A nut portion (not shown) is provided on the lower surface (back surface) side of the X-axis moving table 10, and an X-axis ball screw 12 arranged along the X-axis guide rail 8 is screwed into the nut portion. Has been done. Further, an X-axis pulse motor 14 for rotating the X-axis ball screw 12 is connected to one end of the X-axis ball screw 12. When the X-axis ball screw 12 is rotated by the X-axis pulse motor 14, the X-axis moving table 10 moves in the X-axis direction along the X-axis guide rail 8. The X-axis moving mechanism 6 may be provided with an X-axis measuring unit (not shown) for measuring the position of the X-axis moving table 10 in the X-axis direction.

A cylindrical table base 16 is provided on the upper surface (surface) side of the X-axis moving table 10. Further, a holding table 18 for holding the workpiece 11 is provided on the upper part of the table base 16. When the workpiece 11 is machined by the cutting device 2, the workpiece 11 is held by the holding table 18.

The upper surface of the holding table 18 constitutes a holding surface 18a for holding the workpiece 11. The holding surface 18a is formed substantially parallel to the X-axis direction and the Y-axis direction (indexing feed direction, left-right direction), and a flow path (not shown) formed inside the holding table 18 and the table base 16 is formed. It is connected to a suction source (not shown) such as an ejector via an ejector.

FIG. 2 is a perspective view showing the workpiece 11 held by the holding table 18. The workpiece 11 is, for example, a silicon wafer formed in a disk shape, and includes a front surface 11a and a back surface 11b. The workpiece 11 is divided into a plurality of regions by a plurality of scheduled division lines (streets) 13 arranged in a grid pattern so as to intersect each other, and ICs (Integrated Circuits) are respectively on the surface 11a side of this region. ), LSI (Large Scale Integration) and other devices are formed.

There are no restrictions on the material, shape, structure, size, etc. of the workpiece 11. For example, the workpiece 11 may be a wafer made of a material other than silicon (GaAs, InP, GaN, SiC, etc.), glass, ceramics, resin, metal, or the like. Further, there are no restrictions on the type, quantity, shape, structure, size, arrangement, etc. of the device 15.

When the workpiece 11 is divided along the scheduled division line 13, a plurality of device chips each including the device 15 are obtained. For example, the cutting device 2 is used to divide the workpiece 11.

The workpiece 11 may be supported by an annular frame for convenience of processing and transportation. In this case, a circular tape having a diameter larger than that of the workpiece 11 is attached to the back surface 11b side of the workpiece 11. Further, the outer peripheral portion of the tape is attached to an annular frame having a circular opening having a diameter larger than that of the workpiece 11 in the central portion. As a result, the workpiece 11 is supported by the frame via the tape.

A plurality of clamps 20 (4 in FIG. 1) are provided around the holding table 18. When the workpiece 11 is supported by the frame, the frame is gripped and fixed by the plurality of clamps 20.

Further, the holding table 18 is connected to a rotation drive source (not shown) such as a motor, and rotates about a rotation axis along a direction perpendicular to the holding surface 18a. That is, the holding table 18 rotates around an axis substantially parallel to the Z-axis direction (vertical direction, vertical direction). Further, by moving the X-axis moving table 10 in the X-axis direction by the X-axis moving mechanism 6, the holding table 18 is processed and fed.

A transport mechanism (not shown) for transporting the workpiece 11 onto the holding table 18 is provided in the vicinity of the holding table 18. Further, in the vicinity of the X-axis moving table 10, a case 22 is provided for temporarily storing waste liquid of cutting fluid (pure water or the like) used for cutting. The waste liquid stored inside the case 22 is discharged to the outside of the cutting device 2.

Further, on the upper surface of the base 4, a gate-shaped support structure 24 is arranged so as to straddle the X-axis moving mechanism 6. Two sets of moving units (moving mechanisms) 26 are provided on the upper part of the front surface of the support structure 24. Further, on the front surface side of the support structure 24, a pair of Y-axis guide rails 28 are provided along the Y-axis direction. Each of the moving units 26 is provided with a Y-axis moving plate 30, and the Y-axis moving plate 30 is mounted so as to be slidable in the Y-axis direction along a pair of Y-axis guide rails 28.

Nut portions (not shown) are provided on the rear surface (back surface) side of the Y-axis moving plate 30. Further, a pair of Y-axis ball screws 32 are provided along the Y-axis direction between the pair of Y-axis guide rails 28. One Y-axis ball screw 32 is screwed into each nut portion of the Y-axis moving plate 30. A Y-axis pulse motor 34 is connected to one end of each of the pair of Y-axis ball screws 32.

When the Y-axis ball screw 32 is rotated by the Y-axis pulse motor 34, the Y-axis moving plate 30 moves in the Y-axis direction along the Y-axis guide rail 28. The moving unit 26 may be provided with a Y-axis measuring unit (not shown) for measuring the position of the Y-axis moving plate 30 in the Y-axis direction.

A pair of Z-axis guide rails 36 are arranged along the Z-axis on each of the front (surface) sides of the Y-axis moving plate 30. The Z-axis moving plate 38 is mounted on the Z-axis guide rail 36 in a state where it can slide in the Z-axis direction along the Z-axis guide rail 36.

A nut portion (not shown) is provided on the rear surface (back surface) side of the Z-axis moving plate 38, and a Z-axis ball screw 40 arranged along the Z-axis guide rail 36 is screwed into the nut portion. Has been done. A Z-axis pulse motor 42 is connected to one end of the Z-axis ball screw 40. When the Z-axis ball screw 40 is rotated by the Z-axis pulse motor 42, the Z-axis moving plate 38 moves in the Z-axis direction along the Z-axis guide rail 36.

A cutting unit 44a (first cutting unit) for cutting the workpiece 11 is fixed to the lower portion of the Z-axis moving plate 38 included in the moving unit 26. A cutting unit 44b (second cutting unit) for cutting the workpiece 11 is fixed to the lower portion of the Z-axis moving plate 38 included in the other moving unit 26. Further, an imaging unit (camera) 46 for imaging the workpiece 11 and the like is provided at positions adjacent to the cutting units 44a and 44b, respectively.

The position of the cutting units 44a and 44b is controlled by the moving unit 26. Specifically, by moving the Y-axis moving plate 30 in the Y-axis direction, the positions of the cutting units 44a and 44b and the imaging unit 46 in the Y-axis direction are controlled. Further, by moving the Z-axis moving plate 38 in the Z-axis direction, the cutting units 44a and 44b and the imaging unit 46 move up and down, and the positions (height positions) of the cutting units 44a and 44b and the imaging unit 46 in the Z-axis direction. Is controlled.

The cutting unit 44a includes a tubular housing 48a supported by the moving unit 26. Inside the housing 48a, a spindle 50a (see FIG. 3B) arranged substantially parallel to the Y-axis direction is housed. Further, the cutting unit 44b includes a tubular housing 48b supported by the moving unit 26. Inside the housing 48b, a spindle 50b (see FIG. 5B) arranged substantially parallel to the Y-axis direction is housed.

The tip of the spindle 50a on one end side is exposed to the outside of the housing 48a, and an annular cutting blade 52a (first cutting blade) is mounted on the tip (see FIG. 3B). Further, the tip of the spindle 50b on one end side is exposed to the outside of the housing 48b, and an annular cutting blade 52b (second cutting blade) is mounted on the tip (see FIG. 5B). ..

The cutting blades 52a and 52b include an electroformed hub blade having an annular cutting edge formed by fixing abrasive grains made of diamond or the like with a plating layer made of nickel or the like, or using metal, ceramics, resin or the like for the abrasive grains. A washer-type blade or the like made of an annular cutting edge formed by fixing with a bonding material is used. The materials of the cutting blades 52a and 52b, the particle size of the abrasive grains, and the like are appropriately selected according to the material of the workpiece 11.

The other ends of the spindles 50a and 50b are respectively connected to a rotary drive source (not shown) such as a motor. The cutting blades 52a and 52b mounted on the tips of the spindles 50a and 50b are rotated by the power transmitted from the rotation drive source via the spindles 50a and 50b. At this time, the rotation axes of the cutting blades 52a and 52b are set so as to be along the length direction (Y-axis direction) of the spindles 50a and 50b.

Further, nozzles 54 for supplying a cutting liquid such as pure water to the workpiece 11 and the cutting blades 52a and 52b are provided in the vicinity of the cutting blades 52a and 52b, respectively. When cutting the workpiece 11 with the cutting blades 52a and 52b, the cutting fluid is supplied from the nozzle 54. As a result, the workpiece 11 and the cutting blades 52a and 52b are cooled, and the debris (cutting debris) generated by cutting is washed away.

Further, each of the components of the cutting device 2 (X-axis moving mechanism 6, holding table 18, moving unit 26, cutting units 44a, 44b, imaging unit 46, etc.) is connected to the control unit (control unit) 56. The control unit 56 is configured by, for example, a computer, and controls the operation of the components of the cutting device 2 according to the machining conditions of the workpiece 11.

Next, a specific example of a method of dividing the workpiece 11 into a plurality of device chips by using the above-mentioned cutting device 2 will be described. In the present embodiment, after forming a groove on the front surface 11a side of the workpiece 11 along the planned division line 13, the workpiece 11 is divided by thinning the back surface 11b side of the workpiece 11. Manufacture device chips.

First, the cutting blade 52a is cut into the surface 11a side of the workpiece 11, and the groove 11c is formed along the planned division line 13 (groove formation step). FIG. 3A is a perspective view showing the workpiece 11 in the groove forming step, and FIG. 3B is a cross-sectional view showing the workpiece 11 in the groove forming step.

In the groove forming step, first, the workpiece 11 is held by the holding table 18. Specifically, the workpiece 11 is arranged on the holding table 18 so that the front surface 11a side is exposed upward and the back surface 11b side faces the holding surface 18a. In this state, the work piece 11 is suction-held by the holding surface 18a by applying a negative pressure of a suction source (not shown) to the holding surface 18a.

Next, the holding table 18 is rotated to align the length direction of one scheduled division line 13 with the X-axis direction. Further, the height of the cutting unit 44a is adjusted so that the lower end of the cutting blade 52a is arranged below the front surface 11a of the workpiece 11 and above the back surface 11b of the workpiece 11. Further, the position of the cutting unit 44a in the Y-axis direction is adjusted so that the cutting blade 52a is arranged on the extension line of the one scheduled division line 13.

Then, the holding table 18 is moved along the X-axis direction while rotating the cutting blade 52a. For example, as shown in FIG. 3A, the cutting blade 52a is rotated in the direction indicated by the arrow A, and the holding table 18 is moved in the direction indicated by the arrow B. As a result, the holding table 18 and the cutting blade 52a move relatively along the scheduled division line 13, and the cutting blade 52a moves along the scheduled division line 13 to a predetermined depth on the surface 11a side of the workpiece 11. Cut at the depth of cut). As a result, the workpiece 11 is cut, and a linear groove 11c having a depth less than the thickness of the workpiece 11 is formed on the surface 11a side of the workpiece 11 along the planned division line 13. (Half cut).

In the groove forming step, the cutting depth of the cutting blade 52a is finally divided into a plurality of device chips 19 (see FIGS. 5 (A) and 5 (B)) when the workpiece 11 is finally divided. Set to be equal to or larger than the thickness (finishing thickness) of the device chip 19. As a result, the groove 11c having a depth equal to or greater than the finish thickness is formed in the workpiece 11.

The width of the groove 11c is controlled by the width (thickness) of the cutting blade 52a. The width of the cutting blade 52a is appropriately set according to the distance between adjacent devices 15 (width of the scheduled division line 13), the material of the workpiece 11, the size, and the like. For example, the thickness of the cutting blade 52a is set to 50 μm or more and 100 μm or less.

After that, the same procedure is repeated to form the groove 11c along all the other scheduled division lines 13. As a result, a plurality of grooves 11c are formed in a grid pattern on the surface 11a side of the workpiece 11.

Next, the adhesive tape 17 is attached to the surface 11a side of the workpiece 11 on which the groove 11c is formed (adhesive tape attachment step). FIG. 4A is a perspective view showing a work piece 11 in the adhesive tape sticking step, and FIG. 4B is a cross-sectional view showing a work piece 11 in the adhesive tape sticking step.

In the adhesive tape attaching step, first, the workpiece 11 is held by the holding table 60. The holding table 60 is configured in the same manner as the holding table 18 of the cutting apparatus 2 (see FIGS. 3A and 3B), and includes a holding surface 60a for holding the workpiece 11. The workpiece 11 is suction-held by the holding table 60 so that the front surface 11a side is exposed upward and the back surface 11b side faces the holding surface 60a.

Next, the adhesive tape 17 is attached to the workpiece 11. For example, the adhesive tape 17 includes a circular film-shaped base material having substantially the same diameter as the workpiece 11, and an adhesive layer (glue layer) formed on the base material. The base material is made of a resin such as polyolefin, polyvinyl chloride, or polyethylene terephthalate, and the adhesive layer is made of an ultraviolet curable resin or the like that is cured by irradiation with ultraviolet rays.

The adhesive tape 17 is arranged so that the adhesive layer side faces the work piece 11, and is attached to the surface 11a side of the work piece 11. As a result, the plurality of devices 15 are covered with the adhesive tape 17. The adhesive tape 17 protects the plurality of devices 15 when the back surface 11b side of the workpiece 11 is processed in the back surface cutting step described later. The adhesive tape 17 may be attached by an operator, or may be attached by a dedicated device (tape attaching device) for attaching the adhesive tape 17 to the workpiece 11.

Next, the cutting blade 52b is cut into the back surface 11b side of the workpiece 11, and the entire back surface 11b side of the workpiece 11 is cut (back surface cutting step). FIG. 5 (A) is a perspective view showing the workpiece 11 in the back surface cutting step, and FIG. 5 (B) is a cross-sectional view showing the workpiece 11 in the back surface cutting step.

In the back surface cutting step, first, the workpiece 11 is held by the holding table 18. Specifically, the workpiece 11 is arranged on the holding table 18 so that the front surface 11a side faces the holding surface 18a and the back surface 11b side is exposed upward. In this state, the work piece 11 is suction-held by the holding surface 18a by applying a negative pressure of a suction source (not shown) to the holding surface 18a.

Next, the height of the cutting unit 44b is adjusted so that the lower end of the cutting blade 52b is arranged below the back surface 11b of the workpiece 11 and above the surface 11a of the workpiece 11. At this time, the cutting blade 52b is positioned so that the distance from the lower end of the cutting blade 52b to the surface 11a of the workpiece 11 matches the finishing thickness of the device chip 19.

Then, the holding table 18 is moved along the X-axis direction while rotating the cutting blade 52b. As a result, the holding table 18 and the cutting blade 52b move relatively along the direction parallel to the holding surface 18a and perpendicular to the rotation axis of the cutting blade 52b, and the cutting blade 52b is on the back surface 11b side of the workpiece 11. Cut to a predetermined depth. As a result, the workpiece 11 is linearly cut by the cutting blade 52b, and a linear (strip-shaped) cutting groove is formed on the back surface 11b side of the workpiece 11 (cutting step).

The cutting blade 52b is thicker than the cutting blade 52a (see FIGS. 3A and 3B) used in the groove forming step. Therefore, the cutting blade 52b comes into contact with a wider area of the workpiece 11 during cutting than the cutting blade 52a, and the width of the cutting groove formed by the cutting blade 52b is larger than the width of the groove 11c.

After that, the cutting unit 44b is moved in the Y-axis direction by a distance equal to or less than the width of the cutting blade 52b in a state where the workpiece 11 and the cutting blade 52b are not in contact with each other. As a result, the holding table 18 and the cutting blade 52b move relatively along the direction parallel to the rotation axis of the cutting blade 52b, and the work piece 11 is indexed and fed (cutting blade moving step).

After that, the back surface 11b side of the workpiece 11 is cut with the cutting blade 52b in the same procedure. As a result, a new linear cutting groove is formed so as to be connected to the cutting groove already formed on the back surface 11b of the workpiece 11. Then, the cutting step and the cutting blade moving step are repeated until the entire back surface 11b side of the workpiece 11 is cut and the entire workpiece 11 is thinned.

The thickness of the cutting blade 52b is appropriately set according to the size and material of the workpiece 11, the width of the groove 11c, and the like. However, the thicker the cutting blade 52b, the larger the region of the workpiece 11 to be machined in one cutting, and the number of times the cutting blade 52b is cut into the workpiece 11 is reduced. Therefore, it is preferable to use a cutting blade 52b having a relatively large width in the back surface cutting step.

For example, the width of the cutting blade 52b is set to 0.5 mm or more, preferably 1 mm or more. The upper limit of the width of the cutting blade 52b is not limited, and is set to, for example, 3 mm or less.

When the above cutting step and the cutting blade moving step are alternately repeated and the entire back surface 11b side of the workpiece 11 is cut by the cutting blade 52b, the groove 11c formed in the groove forming step becomes the workpiece 11. It is exposed on the back surface 11b side. As a result, the workpiece 11 is divided along the groove 11c, and a plurality of device chips 19 each including the device 15 are obtained.

As described above, in the present embodiment, the surface 11a side of the workpiece 11 is cut by the cutting blade 52a to form the groove 11c, and then the back surface 11b side of the workpiece 11 is cut by the cutting blade 52b. The workpiece 11 is divided into a plurality of device chips 19. Therefore, when the workpiece 11 is divided into a plurality of device chips 19, the step of grinding and thinning the workpiece 11 using a grinding device can be omitted. This eliminates the need for preparation and operation of the grinding apparatus, and can reduce the number of steps and costs required for manufacturing the device chip 19.

Further, when the workpiece 11 is ground and thinned by using a grinding device as in the conventional case, the grinding wheel rotates in a plane parallel to the back surface 11b of the workpiece 11, and the workpiece 11 is rotated. It is pressed against the back surface 11b side of 11. Then, the grinding wheel moves toward the outside in the radial direction of the workpiece 11 in a state of being in contact with a wide range on the back surface 11b side of the workpiece 11. As a result, the device tip 19 may be pushed out of the workpiece 11 by the grinding wheel, peeled off from the adhesive tape 17, and scattered from the holding table.

In particular, when the workpiece 11 is divided into device chips 19 having a small size (for example, 0.1 mm square), the device chips 19 are likely to scatter. If the device chip 19 is frequently scattered, the yield of the device chip 19 is lowered.

On the other hand, in the present embodiment, the cutting blade 52b is used for thinning the workpiece 11. In this case, since the contact area between the workpiece 11 and the machining tool (cutting blade 52b) is suppressed to a small size, the device chip 19 is less likely to scatter when the workpiece 11 is divided into the device chips 19. As a result, a decrease in the yield of the device chip 19 is suppressed.

In the back surface cutting step, it is preferable that the holding table 18 and the cutting blade 52b are relatively moved so that the moving direction of the lower end of the rotating cutting blade 52b and the moving direction of the holding table 18 coincide with each other. Specifically, as shown in FIG. 5A, the holding table 18 is moved in the direction indicated by the arrow D while rotating the cutting blade 52b in the direction indicated by the arrow C. As a result, the workpiece 11 is cut by a so-called downcut in which the cutting blade 52b is cut from the upper surface (back surface 11b) side to the lower surface (front surface 11a) side of the workpiece 11.

When the workpiece 11 is cut by downcut, the cutting blade 52b cuts from the back surface 11b side of the workpiece 11 toward the surface 11a side, so that the workpiece 11 is pressed against the holding surface 18a side of the holding table 18. Be cut. As a result, the device chip 19 is less likely to scatter during cutting of the workpiece 11.

When the scattering of the device chip 19 was actually evaluated by an experiment, when the workpiece 11 was cut by the cutting blade 52b and thinned as in the present embodiment, the workpiece 11 was cut by the grinding wheel as in the conventional case. It was confirmed that the scattering rate of the device chip 19 was significantly reduced as compared with the case of grinding and thinning.

In this evaluation, first, two 10 mm square and 725 μm-thick workpieces made of silicon were prepared, and a plurality of grooves were formed in a grid pattern on each workpiece (half-cut). After that, one work piece was ground and the other work piece was cut to divide the work piece into 10000 chips each of 0.1 mm square and 100 μm thick. ..

First, the work piece was divided into a plurality of chips by grinding the back surface side of the work piece with a grinding device as in the conventional case. For grinding the work piece, the rotation speed of the holding table that holds the work piece is 300 rpm, the rotation speed of the annular grinding wheel (diameter 300 mm) to which multiple grinding wheels are fixed is 3000 rpm, and the lowering speed of the grinding wheel (work piece). The pressing speed against the work piece) was set to 0.3 μm / s, and this was carried out until a plurality of grooves formed in the work piece were exposed on the back surface side of the work piece. At this time, the number of scattered chips was 25% of the total number of chips.

Next, as described in the present embodiment, the work piece was divided into a plurality of chips by down-cutting by cutting the back surface side of the work piece with a cutting device (see FIG. 1). A cutting blade having a thickness of 1 mm was used for cutting the workpiece, the rotation speed of the cutting blade was set to 30,000 rpm, and the moving speed (machining feed speed) of the holding table 18 was set to 5 mm / s. As a result, the number of chips scattered when the workpiece was divided into a plurality of chips was 7% of the total number of chips.

From the above results, when the workpiece 11 is thinned by cutting using the cutting blade 52b as shown in FIGS. 5 (A) and 5 (B), the scattering of the device chip 19 is significantly reduced. Was confirmed. Therefore, by dividing the workpiece 11 by the back surface cutting step according to the present embodiment, it is possible to suppress a decrease in yield due to scattering of the device chip 19.

Further, when the workpiece 11 is ground by a grinding device as in the conventional case, a thickness measuring device that measures the thickness of the workpiece 11 in order to monitor the thickness of the workpiece 11 being ground. It is necessary to provide. Further, the material and shape of the workpiece 11 are also limited to the range in which the thickness can be measured by the thickness measuring device. On the other hand, in the present embodiment, by controlling the cutting depth of the cutting blade 52b into the workpiece 11, the thickness of the workpiece 11 after the back surface cutting step (finishing thickness of the device chip 19) can be accurately determined. Can be controlled. Therefore, the thickness measuring instrument can be omitted, and the degree of freedom in the material and shape of the workpiece 11 can be improved.

In the present embodiment, as shown in FIGS. 5A and 5B, the process of linearly cutting the back surface 11b side of the workpiece 11 with the cutting blade 52b is repeated to obtain the workpiece 11. An example of thinning the whole was described. However, the mode of the back surface cutting step is not limited to this. For example, in the back surface cutting step, the back surface 11b side of the workpiece 11 may be cut in a spiral shape with the cutting blade 52b.

Specifically, first, the holding table 18 is moved along the X-axis direction while rotating the cutting blade 52b, and the cutting blade 52b is moved to a part of the outer peripheral portion of the workpiece 11 (Y-axis in FIG. 5A). Make a cut in the end in the direction). Then, in a state where the cutting blade 52b cuts into the workpiece 11, the movement of the holding table 18 is stopped.

Next, while rotating the holding table 18 about a rotation axis along the direction perpendicular to the holding surface 18a, the holding table 18 and the cutting blade 52b are moved in a direction parallel to the rotation axis (Y-axis direction) of the cutting blade 52b. Move relatively along. Specifically, with the holding table 18 rotated, the cutting unit 44b is moved in the Y-axis direction by the moving unit 26 (see FIG. 1), and the cutting blade 52b is moved to the center (center) side of the workpiece 11. Move towards.

As a result, the cutting blade 52b cuts the workpiece 11 in an annular shape along the circumferential direction while gradually moving from the outer peripheral edge side to the center side of the workpiece 11. As a result, the back surface 11b side of the workpiece 11 is cut in a spiral shape. The moving speed of the cutting unit 44b at this time is appropriately adjusted so that an uncut region does not occur on the back surface 11b side of the workpiece 11.

When cutting the workpiece 11 in a spiral shape, the cutting blade 52b is cut into the center of the workpiece 11, and then the workpiece 11 is cut in an annular shape from the center side toward the outer peripheral edge side. You may. In this case, the cutting blade 52b is gradually moved from the central portion of the workpiece 11 toward the outer peripheral edge side while rotating the holding table 18.

Further, in the present embodiment, the case where the cutting device 2 includes two sets of cutting units 44a and 44b has been described, but the cutting device 2 may have one set of cutting units. In this case, the cutting blade 52a is attached to the cutting unit to perform the groove forming step, and then the cutting blade 52a is removed from the cutting unit. Then, the cutting blade 52b is attached to the cutting unit, and the back surface cutting step is performed. By setting the number of cutting units provided in the cutting device 2 to one set, the configuration of the cutting device 2 can be simplified and space can be saved.

In addition, the structure, method, etc. according to the above-described embodiment can be appropriately modified and implemented as long as the scope of the object of the present invention is not deviated.

11 Work piece 11a Front surface 11b Back surface 13 Scheduled division line (street)
15 Device 17 Adhesive tape 19 Device chip 2 Cutting device 4 Base 4a Top surface 6 X-axis movement mechanism 8 X-axis guide rail 10 X-axis movement table 12 X-axis ball screw 14 X-axis pulse motor 16 Table base 18 Holding table 18a Holding surface 20 Clamp 22 Case 24 Support structure 26 Moving unit (moving mechanism)
28 Y-axis guide rail 30 Y-axis moving plate 32 Y-axis ball screw 34 Y-axis pulse motor 36 Z-axis guide rail 38 Z-axis moving plate 40 Z-axis ball screw 42 Z-axis pulse motor 44a, 44b Cutting unit 46 Imaging unit (camera) )
48a, 48b Housing 50a, 50b Spindle 52a, 52b Cutting blade 54 Nozzle 56 Control unit (control unit)
60 Holding table 60a Holding surface

Claims (4)

A method for manufacturing a device chip, which divides a workpiece having a device formed on the surface side of a plurality of regions partitioned by a plurality of scheduled division lines intersecting with each other into a plurality of device chips.
A groove forming step in which a first cutting blade is cut into the surface side of the workpiece to form a groove having a depth equal to or greater than the thickness of the device chip along the planned division line.
An adhesive tape attaching step of attaching the adhesive tape to the surface side of the workpiece in which the groove is formed, and
A second cutting blade thicker than the first cutting blade is cut into the back surface side of the work piece, and the work piece is made so that the thickness of the work piece is the thickness of the device chip. A device comprising a back surface cutting step of exposing the groove to the back surface side of the workpiece by cutting the entire back surface side to divide the workpiece into a plurality of device chips. How to make chips. In the backside cutting step
The holding table that holds the workpiece and the second cutting blade are relatively moved so that the moving direction of the lower end of the rotating second cutting blade coincides with the moving direction of the holding table. The method for manufacturing a device chip according to claim 1, wherein the second cutting blade is cut from the back surface side to the front surface side of the workpiece. In the backside cutting step
While moving the holding table for holding the workpiece on the holding surface and the second cutting blade in a direction parallel to the holding surface and perpendicular to the rotation axis of the second cutting blade. , The cutting step of cutting the workpiece with the second cutting blade,
A cutting blade moving step in which the holding table and the second cutting blade are relatively moved along a direction parallel to the rotation axis of the second cutting blade.
The method for manufacturing a device chip according to claim 1 or 2, wherein the entire back surface side of the workpiece is cut by repeating the above. In the backside cutting step
While rotating the holding table that holds the workpiece on the holding surface around a rotation axis along the direction perpendicular to the holding surface, the holding table and the second cutting blade are cut into the second cutting. The method for manufacturing a device chip according to claim 1 or 2, wherein the back surface side of the workpiece is cut in a spiral shape by moving it relatively along a direction parallel to the rotation axis of the blade.