JP7614708B2 - How the chip is manufactured - Google Patents

Description

The present invention relates to a method for manufacturing chips by dividing a workpiece to produce multiple chips.

Various types of wafers made of silicon, gallium arsenide, sapphire, etc. are used to manufacture chips that are incorporated into various electronic devices such as mobile phones and personal computers. The wafer is divided into multiple regions by multiple planned division lines (streets) that intersect with each other, and devices are formed in each region. By dividing this wafer along the planned division lines, multiple chips (device chips), each equipped with a device, are obtained.

For example, a cutting device is used to divide the workpiece, such as the wafer. The cutting device is equipped with a chuck table that holds the workpiece, and a cutting unit to which an annular cutting blade is attached. The cutting blade is rotated and cuts into the workpiece held by the chuck table, cutting and dividing the workpiece.

When dividing a workpiece with a cutting blade, the cutting blade's cutting depth is adjusted so that the bottom end of the cutting blade reaches the back surface (lower surface) of the workpiece, and the cutting blade is caused to cut into the workpiece (full cut). At this time, the cutting blade may come into contact with the back surface of the workpiece, causing chipping on the back surface of the workpiece. If this chipping remains in the chip, the flexural strength (bending strength) of the chip will decrease, and the quality of the chip will deteriorate.

In response, efforts are being made to develop a process that can prevent chipping when cutting a workpiece with a cutting blade. For example, Patent Document 1 discloses a method that includes a step of cutting a cutting blade into the workpiece to form a groove along the intended division line that is deep enough not to reach the back surface of the workpiece, and a step of cutting the workpiece by cutting the cutting blade again along the groove.

JP 2020-113564 A

Cutting the workpiece in two stages as described above reduces the occurrence of chipping on the back side of the workpiece. However, when using this method, it is necessary to cut the cutting blade into the workpiece at least twice along each of the planned dividing lines set on the workpiece. As a result, the processing efficiency of the workpiece decreases, and the chip production efficiency also decreases.

The present invention was made in consideration of such problems, and aims to provide a chip manufacturing method that can improve chip production efficiency while suppressing the occurrence of chipping.

According to one aspect of the present invention, there is provided a method for manufacturing chips by dividing a workpiece partitioned into a plurality of regions by first and second planned division lines that intersect with each other, the method including: a first cutting step of cutting a first cutting blade into the workpiece along the first planned division line to form a cutting groove having a depth less than the thickness of the workpiece along the first planned division line; a second cutting step of cutting a second cutting blade into the workpiece along the second planned division line to divide the workpiece along the second planned division line; and a dividing step of applying an external force to the workpiece to divide the workpiece along the first planned division line starting from the cutting groove.

The workpiece is preferably a crystalline wafer in which chipping developing from the first planned division line is more likely to occur than chipping developing from the second planned division line. Also, the workpiece preferably has an orientation flat that indicates the crystal orientation of the workpiece, and one of the first planned division line or the second planned division line is set along a direction parallel to the orientation flat, and the other of the first planned division line or the second planned division line is set along a direction perpendicular to the orientation flat.

Also, preferably, in the first cutting step, the first cutting blade is vibrated along the radial direction of the first cutting blade at a frequency that belongs to the ultrasonic band while cutting into the workpiece. Also, preferably, in the second cutting step, the second cutting blade is vibrated along the radial direction of the second cutting blade at a frequency that belongs to the ultrasonic band while cutting into the workpiece.

Also, preferably, the second cutting step is performed after the first cutting step and before the division step. Also, preferably, the chip manufacturing method further includes a tape application step of applying tape to the workpiece, and in the division step, the external force is applied to the workpiece by expanding the tape.

In one embodiment of the chip manufacturing method of the present invention, the workpiece is divided along a first planned division line by forming a cutting groove and applying an external force, and the workpiece is divided along a second planned division line by cutting the workpiece. By using this chip manufacturing method, it is possible to avoid collision between the cutting blade and the back side of the workpiece along the first planned division line, where chipping is likely to occur, and to suppress the occurrence of chipping on the back side of the workpiece. In addition, along the second planned division line, where chipping is unlikely to occur, the workpiece is divided by cutting only once with the cutting blade, simplifying the workpiece division process. This makes it possible to improve the production efficiency of chips while suppressing the occurrence of chipping.

FIG. FIG. FIG. FIG. 2 is a cross-sectional view showing a cutting unit. FIG. 11 is a perspective view showing the workpiece in the tape application step. 2 is a partial cross-sectional side view showing a workpiece held by a chuck table. FIG. FIG. 7A is a cross-sectional view showing a part of the workpiece in the first cutting step, and FIG. 7B is a cross-sectional view showing a part of the workpiece in which a cut groove has been formed. FIG. 2 is a perspective view showing the workpiece after a first cutting step. FIG. 9A is a cross-sectional view showing a part of the workpiece in the second cutting step, and FIG. 9B is a cross-sectional view showing a part of the workpiece in which a kerf has been formed. FIG. 4 is a perspective view showing the workpiece after the second cutting step. FIG. 11A is a cross-sectional view showing the workpiece in the dividing step, and FIG. 11B is a cross-sectional view showing the workpiece divided into a plurality of chips. FIG. 11 is a perspective view showing the workpiece in the tape application step. FIG. 13A is a cross-sectional view showing a part of the workpiece in the first cutting step, and FIG. 13B is a cross-sectional view showing a part of the workpiece in which a cut groove has been formed. FIG. 4 is a cross-sectional view showing the workpiece when the tape is shrunk. FIG. 11 is a perspective view showing the workpiece in the tape replacement step.

(Embodiment 1)
Hereinafter, the present embodiment will be described with reference to the accompanying drawings. First, an example of the configuration of a cutting device that can be used in the manufacturing method of the tip according to the present embodiment will be described. FIG. 1 is a perspective view showing a cutting device 2. In FIG. 1, the X-axis direction (processing feed direction, left-right direction, first horizontal direction) and the Y-axis direction (indexing feed direction, front-back direction, second horizontal direction) are perpendicular to each other. Also, the Z-axis direction (vertical direction, up-down direction, height direction) is perpendicular to the X-axis direction and the Y-axis direction.

The cutting device 2 includes a base 4 that supports or houses each of the components that make up the cutting device 2. An opening 4a is formed in a corner on the front end side of the base 4, and inside the opening 4a, a cassette support table 6 that moves (lifts and lowers) along the Z-axis direction by a lifting mechanism (not shown) is provided. A cassette 8 capable of housing multiple workpieces to be machined by the cutting device 2 is mounted on the cassette support table 6. Note that in FIG. 1, the outline of the cassette 8 is indicated by a two-dot chain line.

Figure 2 is a perspective view showing the workpiece 11. The workpiece 11 is a crystalline wafer formed into a disk shape, and has a front surface 11a and a back surface 11b that are generally parallel to each other. For example, the workpiece 11 may be a single crystal silicon wafer, a single crystal wafer made of a III-V group compound semiconductor such as gallium arsenide (GaAs), a sapphire wafer, or the like.

The workpiece 11 is divided into a number of rectangular regions by a number of planned division lines (streets) 13a, 13b arranged in a grid pattern so as to intersect with each other. In addition, devices 15 such as ICs (Integrated Circuits), LSIs (Large Scale Integration), LEDs (Light Emitting Diodes), and MEMS (Micro Electro Mechanical Systems) devices are formed on the surface 11a side of each of the multiple regions.

By dividing the workpiece 11 along the planned division lines 13a and 13b, multiple chips (device chips) each having a device 15 are manufactured. However, there are no restrictions on the material, shape, structure, size, etc. of the workpiece 11. There are also no restrictions on the type, number, shape, structure, size, arrangement, etc. of the devices 15, and the device 15 does not have to be formed on the workpiece 11.

Orientation flats (notches) 17a and 17b that indicate the crystal orientation of the workpiece 11 are provided on a portion of the outer periphery of the workpiece 11. The orientation flats 17a and 17b correspond to a portion of the outer periphery (side) of the workpiece 11 that is formed in a straight line in a plan view.

The orientation flats 17a and 17b are formed by cutting off a portion of the outer periphery of the workpiece 11 in a straight line, which is in a predetermined positional relationship with the crystal orientation of the workpiece 11. In other words, the orientation flats 17a and 17b are formed in a predetermined position corresponding to the crystal orientation of the workpiece 11. Therefore, by checking the position of the orientation flats 17a and 17b, the crystal orientation of the workpiece 11 can be ascertained.

The workpiece 11 may be provided with only one of the orientation flats 17a and 17b. Also, the workpiece 11 may be provided with a notch instead of the orientation flats 17a and 17b.

As shown in FIG. 1, a transport unit (transport mechanism) 10 that transports the workpiece 11 is provided behind the opening 4a. The transport unit 10 is configured to be movable along the Y-axis direction, and transports the workpiece 11 out of the cassette 8 and into the cassette 8. In addition, a gripper 10a that grips a frame 21 (see FIG. 5) that supports the workpiece 11 is provided at the end of the transport unit 10 on the opening 4a side (cassette 8 side).

Between the opening 4a and the transport unit 10, there is provided a temporary placement area 12 where the workpiece 11 unloaded from the cassette 8 or the workpiece 11 to be loaded into the cassette 8 is temporarily placed. The temporary placement area 12 is provided with a pair of guide rails 14 arranged generally parallel to each other along the Y-axis direction. The pair of guide rails 14 move toward and away from each other along the X-axis direction, and align the workpiece 11 by sandwiching the frame 21 (see FIG. 5).

A transport unit (transport mechanism) 16 that transports the workpiece 11 is provided near the temporary placement area 12. For example, the transport unit 16 includes a number of suction pads that hold the upper surface of the frame 21 (see FIG. 5) by suction.

A rectangular opening 4b is provided on the side of the opening 4a, with its longitudinal direction aligned with the X-axis direction. A moving unit (moving mechanism) 18 equipped with a flat moving table 18a is provided inside the opening 4b. The moving unit 18 is, for example, a ball screw type moving mechanism, and moves the moving table 18a along the X-axis direction. In addition, bellows-shaped dust-proof and drip-proof covers 20 that expand and contract along the X-axis direction are provided on both sides of the moving table 18a to cover the components of the moving unit 18.

A chuck table (holding table) 22 that holds the workpiece 11 is provided on the moving table 18a. The upper surface of the chuck table 22 is a flat surface that is roughly parallel to the horizontal direction (XY plane direction) and constitutes a holding surface 22a that holds the workpiece 11. The holding surface 22a is connected to a suction source (not shown) such as an ejector via a flow path (not shown) and a valve (not shown) provided inside the chuck table 22. In addition, a plurality of clamps 24 that grip and fix the frame 21 (see FIG. 5) are provided around the periphery of the chuck table 22.

The moving unit 18 moves the chuck table 22 together with the moving table 18a along the X-axis direction. The moving unit 18 positions the chuck table 22 between a transport area A where the workpiece 11 is transported and a processing area B where the workpiece 11 is processed. A rotational drive source (not shown) such as a motor is connected to the chuck table 22, and this rotational drive source rotates the chuck table 22 around a rotation axis that is roughly parallel to the Z-axis direction.

In the processing area B, a cutting unit 26 is provided that performs cutting processing on the workpiece 11. An annular cutting blade 28 is attached to the cutting unit 26. The cutting unit 26 cuts the workpiece 11 by rotating the cutting blade 28 and cutting into the workpiece 11.

A moving unit (moving mechanism, not shown) that moves the cutting unit 26 along the Y-axis direction and the Z-axis direction is connected to the cutting unit 26. For example, the moving unit is a ball screw type moving mechanism that includes a Y-axis ball screw arranged along the Y-axis direction and a Z-axis ball screw arranged along the Z-axis direction. This moving unit adjusts the position of the cutting blade 28 attached to the cutting unit 26 in the Y-axis direction and the Z-axis direction.

The cutting unit 26 also includes a nozzle (not shown) that supplies liquid (cutting fluid) such as pure water. When cutting the workpiece 11 with the cutting blade 28, cutting fluid is supplied from the nozzle to the workpiece 11 and the cutting blade 28. This cools the workpiece 11 and the cutting blade 28, and washes away any debris (cutting debris) generated by cutting the workpiece 11.

At a position overlapping with the movement path of the chuck table 22 (between the transport area A and the processing area B), an imaging unit 30 is provided to capture images of the workpiece 11 held by the chuck table 22. For example, the imaging unit 30 includes a visible light camera equipped with an imaging element that receives visible light and converts it into an electrical signal, and an infrared camera equipped with an imaging element that receives infrared light and converts it into an electrical signal. The image captured by the imaging unit 30 is used for aligning the workpiece 11 with the cutting unit 26, etc.

A cleaning unit (cleaning mechanism) 32 for cleaning the workpiece 11 is provided behind the chuck table 22. For example, the cleaning unit 32 includes a spinner table that holds and rotates the workpiece 11, and a nozzle that supplies a cleaning fluid toward the workpiece 11 held by the spinner table. As the cleaning fluid, a mixed fluid in which a liquid (e.g., pure water) and a gas (e.g., air) are mixed is used.

Above the cleaning unit 32, a transport unit (transport mechanism) 34 is provided to transport the workpiece 11 between the chuck table 22 and the cleaning unit 32. For example, the transport unit 34 includes a number of suction pads that hold the upper surface of the frame 21 (see FIG. 5) by suction.

The workpiece 11 cut by the cutting unit 26 is transported from the chuck table 22 to the cleaning unit 32 by the transport unit 34, and is cleaned by the cleaning unit 32. After cleaning, the workpiece 11 is transported onto the pair of guide rails 14 by the transport unit 16, and then gripped by the gripping portion 10a of the transport unit 10 and stored in the cassette 8.

The cutting device 2 also includes a display section (display unit, display device) 36 that displays various information related to the cutting device 2. Furthermore, an input section (input unit, input device) 38 is provided at the front end of the base 4 for inputting various information to the cutting device 2.

As the display unit 36, various displays are used. As the input unit 38, an operation panel with multiple operation keys, a mouse, a keyboard, etc. are used. The cutting device 2 may also be equipped with a touch panel that functions as a user interface. In this case, the touch panel functions as the display unit 36 and the input unit 38, and the operator can input information to the cutting device 2 by touching the touch panel.

Each of the components that make up the cutting device 2 (cassette support table 6, transport unit 10, guide rail 14, transport unit 16, moving unit 18, chuck table 22, clamp 24, cutting unit 26, imaging unit 30, cleaning unit 32, transport unit 34, display unit 36, input unit 38, etc.) is connected to a control unit (control unit, control device) 40. The control unit 40 controls the operation of the cutting device 2 by generating control signals that control the operation of each component of the cutting device 2.

For example, the control unit 40 is configured by a computer and includes a calculation unit that performs calculations necessary for the operation of the cutting device 2, and a storage unit that stores various information (data, programs, etc.) used in the calculations in the calculation unit. The calculation unit includes a processor such as a CPU (Central Processing Unit). The storage unit includes various memories that function as a main storage device, an auxiliary storage device, etc.

The cutting device 2 performs cutting on the workpiece 11. In this embodiment, a cutting unit 26 is used that can vibrate the cutting blade 28 at a frequency that belongs to the ultrasonic band. Figure 3 is an exploded perspective view showing the cutting unit 26.

A cutting blade 28 is attached to the cutting unit 26. A washer-type cutting blade (washer blade) can be used as the cutting blade 28. The washer blade is an annular cutting edge formed by fixing abrasive grains made of diamond, cubic boron nitride (cBN), etc. with a binder made of metal, ceramics, resin, etc. The cutting blade 28 has a first surface 28a and a second surface 28b that are generally parallel to each other. In addition, a circular opening 28c is provided in the center of the cutting blade 28, penetrating the cutting blade 28 in the thickness direction.

However, a hub-type cutting blade (hub blade) may be used as the cutting blade 28. The hub blade is composed of an annular base made of a metal such as an aluminum alloy and an annular cutting edge formed along the outer periphery of the base. The cutting edge of the hub blade is composed of an electroformed grinding wheel in which abrasive grains are fixed with a bonding material such as a nickel-plated layer, for example.

The cutting unit 26 includes a housing 42 formed in a hollow cylindrical shape. The housing 42 accommodates a cylindrical spindle 44 arranged along the Y-axis direction. The tip (one end) of the spindle 44 is exposed from the housing 42, and a threaded portion (male thread) 44a is formed on the outer circumferential surface of the tip of the spindle 44. A rotational drive source (not shown), such as a motor, that rotates the spindle 44 is connected to the base end (the other end) of the spindle 44.

A mount 46 on which the cutting blade 28 is attached is fixed to the tip of the spindle 44. The mount 46 has a disk-shaped flange portion 48 that supports the cutting blade 28, and a cylindrical support shaft (boss portion) 50 that protrudes from the center of the surface 48a of the flange portion 48. The mount 46 has a cylindrical opening 46a that penetrates the center of the flange portion 48 and the center of the support shaft 50. In addition, a threaded portion (male thread) 50a is formed on the outer peripheral surface of the tip of the support shaft 50.

The mount 46 is attached to the spindle 44 so that the tip of the spindle 44 is inserted into the opening 46a. In this state, when the annular fixing nut 52 is screwed onto the threaded portion 44a of the spindle 44 and tightened, the mount 46 is fixed to the tip of the spindle 44.

In addition, an annular flange (pressing flange) 54 made of metal or the like is attached to the mount 46. The flange 54 has a first surface (front surface) 54a and a second surface (back surface) 54b (see FIG. 4) that are generally parallel to each other. In addition, a cylindrical opening 54c is provided in the center of the flange 54, penetrating the flange 54 in the thickness direction.

When the support shaft 50 of the mount 46 is inserted into the opening 28c of the cutting blade 28 and the opening 54c of the flange 54 in that order, the cutting blade 28 and the flange 54 are attached to the mount 46. In this state, when the annular fixing nut 56 is screwed onto the threaded portion 50a of the support shaft 50 and tightened, the cutting blade 28 and the flange 54 are fixed to the mount 46. As a result, the cutting blade 28 is clamped between the flange portion 48 and the flange 54 of the mount 46 and fixed to the tip of the spindle 44.

When the cutting blade 28 is attached to the tip of the spindle 44 and the spindle 44 is rotated by a rotary drive source connected to the spindle 44, the cutting blade 28 rotates at a predetermined number of revolutions around a rotation axis that is roughly parallel to the Y-axis direction.

Figure 4 is a cross-sectional view showing the cutting unit 26. An annular protrusion 48b protruding from a surface 48a is provided along the outer periphery of the flange portion 48 of the mount 46. In addition, a plurality of through holes (slits) 48c penetrating the flange portion 48 in the thickness direction are provided inside the protrusion 48b. For example, four arc-shaped through holes 48c are formed in the flange portion 48 at approximately equal intervals along the circumferential direction of the flange portion 48 (see Figure 3).

On the other hand, an annular protrusion 54d protruding from the second surface 54b is provided along the outer periphery of the flange 54. In addition, a plurality of through holes (slits) 54e penetrating the flange 54 in the thickness direction are provided inside the protrusion 54d. For example, four arc-shaped through holes 54e are formed in the flange 54 at approximately equal intervals along the circumferential direction of the flange 54 (see FIG. 3).

The tip surface of the convex portion 48b of the flange portion 48 is provided with an annular support member 58a that supports the first surface 28a side of the cutting blade 28. In addition, the tip surface of the convex portion 54d of the flange 54 is provided with an annular support member 58b that supports the second surface 28b side of the cutting blade 28. The support members 58a and 58b are made of synthetic resin or the like, and contact the cutting blade 28 to clamp it. Note that the support members 58a and 58b are preferably members having a hardness of 40 or more as measured by a durometer type D.

A vibrator 60a is provided inside the convex portion 48b of the flange portion 48. Also, a vibrator 60b is provided inside the convex portion 54d of the flange 54. For example, the vibrators 60a and 60b are fixed to the flange portion 48 and the flange 54, respectively, by adhesive. The vibrators 60a and 60b constitute a vibration imparting unit 60 that vibrates the cutting blade 28 at a frequency that belongs to the ultrasonic band.

When the cutting blade 28 and flange 54 are attached to the mount 46, the cutting blade 28 is fixed by being sandwiched between the support members 58a and 58b. The cutting blade 28 is then positioned so that the first surface 28a faces the transducer 60a and the second surface 28b faces the transducer 60b.

The vibrator 60a includes an annular piezoelectric body 62a arranged along the circumferential direction of the flange portion 48, a pair of electrodes 64a arranged to sandwich the piezoelectric body 62a, and an insulator 66a that covers the piezoelectric body 62a and the pair of electrodes 64a. Similarly, the vibrator 60b includes an annular piezoelectric body 62b arranged along the circumferential direction of the flange 54, a pair of electrodes 64b arranged to sandwich the piezoelectric body 62b, and an insulator 66b that covers the piezoelectric body 62b and the pair of electrodes 64b. For example, the piezoelectric bodies 62a and 62b are made of piezoelectric ceramics such as barium titanate, lead zirconate titanate, and lithium tantalate.

In addition, wiring 68a, 68b is provided inside the mount 46. One end of the wiring 68a, 68b is branched into two and exposed on the side of the support shaft 50. One electrode 64a of the vibrator 60a is connected to the wiring 68a via a lead wire 70a. The other electrode 64a of the vibrator 60a is connected to the wiring 68b via a lead wire 70b.

The flange 54 is provided with connection electrodes 72a and 72b exposed at the opening 54c. One electrode 64b of the vibrator 60b is connected to the wiring 68a via the lead wire 70c and the connection electrode 72a. The other electrode 64b of the vibrator 60b is connected to the wiring 68b via the lead wire 70d and the connection electrode 72b.

The cutting unit 26 further includes a voltage supply unit 74 that supplies AC voltage to the transducers 60a and 60b. The voltage supply unit 74 includes a power receiving section (power receiving unit) 76 provided on the back side (housing 42 side) of the mount 46, and a power supply section (power supply unit) 82 disposed on the front side (mount 46 side) of the housing 42 and facing the power receiving section 76.

The power receiving unit 76 has an annular core 78 provided on the back side of the mount 46. An annular recess 78a is formed on the front side (the power supply unit 82 side) of the core 78, and an annular coil (power receiving coil) 80 is provided inside the recess 78a. One end of the coil 80 is connected to the wiring 68a, and the other end of the coil 80 is connected to the wiring 68b.

The power supply unit 82 includes an annular core 84. For example, the core 84 is fixed to the surface side of the housing 42 by a bolt (not shown). An annular recess 84a is formed on the surface side (the power receiving unit 76 side) of the core 84, and an annular coil (power supply coil) 86 is provided inside the recess 84a. The coil 86 is connected to an AC power source 90 via wiring 88a and 88b. In addition, a frequency converter 92 that controls the frequency of the AC voltage supplied from the AC power source 90 is connected to the AC power source 90.

The power receiving unit 76 and the power supply unit 82 constitute a rotary transformer that transmits the AC voltage supplied from the AC power source 90 to the vibration imparting unit 60. When the cutting blade 28 processes the workpiece 11, the AC power source 90 applies an AC voltage to the coil 86 of the power supply unit 82. At this time, the frequency of the AC voltage is controlled by the frequency converter 92.

The AC voltage applied to the coil 86 is supplied to the pair of electrodes 64a of the vibrator 60a and the pair of electrodes 64b of the vibrator 60b via the coil 80 of the power receiving unit 76, the wiring 68a, 68b, and the lead wires 70a, 70b, 70c, and 70d. This causes the piezoelectric body 62a of the vibrator 60a to vibrate in the radial direction together with the mount 46. Also, the piezoelectric body 62b of the vibrator 60b to vibrate in the radial direction together with the flange 54. As a result, the cutting blade 28, which is sandwiched between the mount 46 and the flange 54, vibrates in the radial direction of the cutting blade 28.

The frequency of the AC voltage supplied from the AC power source 90 is controlled by a frequency converter 92 so that the cutting blade 28 vibrates at a frequency that belongs to the ultrasonic band. In addition, a plurality of through holes 48c are provided in the flange portion 48 of the mount 46, and a plurality of through holes 54e are provided in the flange 54 (see FIG. 3). This reduces the rigidity of the flange portion 48 and the flange 54 in the radial direction, making it easier for the flange portion 48 and the flange 54 to vibrate in the radial direction. As a result, the cutting blade 28 also vibrates easily in the radial direction.

The workpiece 11 is cut by the cutting device 2, and the workpiece 11 is divided into a plurality of chips. Below, a specific example of the method for manufacturing chips according to this embodiment is described.

First, prepare the workpiece 11 shown in Figure 2. If a cutting blade 28 (see Figure 3, etc.) is inserted into the workpiece 11 to cut it, the cutting blade 28 may come into contact with the back surface 11b of the workpiece 11, causing chipping on the back surface 11b of the workpiece 11. This chipping progresses from the kerf (cut) formed by the cutting blade 28 along a direction that intersects with the planned division lines 13a, 13b.

Depending on the material and structure of the workpiece 11, the likelihood of chipping on the back surface 11b of the workpiece 11 varies depending on the cutting direction by the cutting blade 28. For example, when the workpiece 11 is a crystalline wafer such as a single crystal silicon wafer, a single crystal gallium arsenide wafer, or a sapphire wafer, it has been confirmed that the size of the chipping that develops from the planned division line 13a tends to differ from the size of the chipping that develops from the planned division line 13b. Such anisotropy of the chipping is due to the crystal orientation of the crystalline wafer, and is presumably dependent on the angle between the cleavage plane of the crystalline wafer and the planned division lines 13a and 13b.

In this embodiment, before machining the workpiece 11, a workpiece (test workpiece) having the same material and shape as the workpiece 11 is cut in advance in multiple directions with the cutting blade 28, and the size of chipping that develops from the kerf is measured. This identifies the directions in the workpiece 11 in which chipping is likely to occur and the directions in which it is unlikely to occur. The directions of the planned division lines 13a and 13b are then set so that chipping that develops from the planned division line 13a (first chipping) is more likely to occur than chipping that develops from the planned division line 13b (second chipping).

The likelihood of chipping can be defined based on the average chip size. Specifically, when the cutting blade 28 cuts the workpiece 11 along the planned division lines 13a and 13b, if the average length of the first chipping in the direction perpendicular to the planned division line 13a is greater than the average length of the second chipping in the direction perpendicular to the planned division line 13b, it can be said that the first chipping is more likely to occur than the second chipping.

In this embodiment, the planned division line 13a (first planned division line) is set along a direction parallel to the orientation flat 17a and perpendicular to the orientation flat 17b. The planned division line 13b (second planned division line) is set along a direction perpendicular to the orientation flat 17a and parallel to the orientation flat 17b.

Next, tape is applied to the workpiece 11 (tape application step). FIG. 5 is a perspective view showing the workpiece 11 in the tape application step. In the tape application step, tape 19 is applied to the back surface 11b side of the workpiece 11.

For example, the tape 19 includes a film-like substrate formed into a circular shape and an adhesive layer (glue layer) provided on the substrate. The tape 19 is preferably an expandable tape that can be expanded (stretched) by application of an external force. In this case, in the division step described below, an external force can be applied to the workpiece 11 by expanding the tape 19. For example, the substrate is made of a resin such as polyolefin or polyvinyl chloride. The adhesive layer is made of an epoxy-based, acrylic-based, or rubber-based adhesive. The adhesive layer may be made of an ultraviolet-curable resin that is cured by exposure to ultraviolet light.

The outer periphery of the tape 19 is attached to an annular frame 21 made of a metal such as SUS (stainless steel). A cylindrical opening 21a having a diameter larger than that of the workpiece 11 is provided in the center of the frame 21 so as to penetrate the frame 21 in the thickness direction. With the workpiece 11 placed inside the opening 21a, the center of the tape 19 is attached to the back surface 11b side of the workpiece 11, and the outer periphery of the tape 19 is attached to the frame 21. As a result, the workpiece 11 is supported by the frame 21 via the tape 19. Then, the workpiece 11, supported by the frame 21, is stored in the cassette 8 shown in FIG. 1.

When the workpiece 11 is processed by the cutting device 2, the transport unit 10 first moves toward the cassette 8 and grips the end of the frame 21 housed in the cassette 8 with the gripping portion 10a. The transport unit 10 then moves away from the cassette 8 along the Y-axis direction. This causes the workpiece 11 to be pulled out of the cassette 8 and placed on the pair of guide rails 14.

The pair of guide rails 14 approach each other while supporting the frame 21 from below, sandwiching the frame 21. This aligns the workpiece 11. The frame 21 is then held by suction by the transport unit 16, and the workpiece 11 is transported to the chuck table 22 positioned in the transport area A.

Figure 6 is a partial cross-sectional side view showing the workpiece 11 held by the chuck table 22. The workpiece 11 is placed on the holding surface 22a of the chuck table 22 via the tape 19. The frame 21 is fixed by a number of clamps 24. In this state, when negative pressure from a suction source is applied to the holding surface 22a, the workpiece 11 is suction-held by the chuck table 22 via the tape 19.

Next, the cutting blade 28 is caused to cut into the workpiece 11 along the intended division line 13a to form a cutting groove whose depth is less than the thickness of the workpiece 11 along the intended division line 13a (first cutting step). Figure 7 (A) is a cross-sectional view showing a portion of the workpiece 11 in the first cutting step.

In the first cutting step, first, the chuck table 22 is rotated to align the length direction of the planned division line 13a with the X-axis direction. In addition, the position of the cutting unit 26 in the Z-axis direction is adjusted so that the lower end of the cutting blade 28 is positioned below the front surface 11a of the workpiece 11 and above the back surface 11b of the workpiece 11. Furthermore, the position of the cutting unit 26 in the Y-axis direction is adjusted so that the cutting blade 28 is positioned on an extension of the planned division line 13a.

Then, while rotating the cutting blade 28, the chuck table 22 is moved along the X-axis direction. As a result, the chuck table 22 and the cutting blade 28 move relatively along the X-axis direction (processing feed), and the cutting blade 28 cuts into the surface 11a of the workpiece 11 along the planned division line 13a.

Figure 7 (B) is a cross-sectional view showing a part of the workpiece 11 in which the cutting grooves 23 have been formed. When the cutting blade 28 is cut into the workpiece 11, cutting grooves 23 with a depth less than the thickness of the workpiece 11 are formed along the intended division lines 13a on the surface 11a side of the workpiece 11. Then, by repeating the same procedure, cutting grooves 23 are formed along all of the intended division lines 13a.

When cutting the cutting blade 28 into the workpiece 11, it is preferable to vibrate the cutting blade 28 in the radial direction of the cutting blade 28 by the vibration imparting unit 60 (see FIG. 4). At this time, the vibration imparting unit 60 vibrates the cutting blade 28 at a frequency that belongs to the ultrasonic band. For example, the vibration frequency of the cutting blade 28 is set to 20 kHz or higher. When vibration is imparted to the cutting blade 28 by the vibration imparting unit 60, the cutting blade 28 vibrates so that its diameter increases or decreases. The amount of variation in the diameter of the cutting blade 28 (the difference between the maximum and minimum diameters) is, for example, about 5 μm.

When the vibrating cutting blade 28 cuts into the workpiece 11, the vibration of the cutting blade 28 at a frequency that belongs to the ultrasonic band (ultrasonic vibration) causes the abrasive grains exposed from the lower end of the cutting blade 28 to collide with the workpiece 11 at a frequency that corresponds to the ultrasonic vibration. This causes the workpiece 11 to fracture, making it easier to form the cutting grooves 23.

Figure 8 is a perspective view showing the workpiece 11 after the first cutting step. As shown in Figure 8, a cutting groove 23 is formed on the front surface 11a side of the workpiece 11, the cutting groove 23 being deep enough not to reach the back surface 11b, and extending generally parallel to the intended division line 13a.

If the cutting depth of the cutting blade 28 (the difference in height between the surface 11a of the workpiece 11 and the bottom end of the cutting blade 28) is set to be greater than or equal to the thickness of the workpiece 11, the cutting blade 28 cuts the workpiece 11 (full cut). At that time, the vibrating cutting blade 28 collides with the back surface 11b of the workpiece 11, causing chipping on the back surface 11b side of the workpiece 11. In particular, as described above, chipping that develops from the planned division line 13a is more likely to occur than chipping that develops from the planned division line 13b, so large chips are more likely to form on the back surface 11b of the workpiece 11.

Meanwhile, in the first cutting step, the cutting depth of the cutting blade 28 is set so that the cutting blade 28 does not reach the back surface 11b of the workpiece 11. Therefore, the vibrating cutting blade 28 does not collide with the back surface 11b of the workpiece 11, and chipping on the back surface 11b side of the workpiece 11 is avoided.

In particular, when the fracture toughness value of the workpiece 11 is 3.0 MPa·m ^1/2 or less, the workpiece 11 is likely to be broken by the collision of the vibrating cutting blade 28, and machining defects are likely to occur. Therefore, when cutting such a workpiece 11, it is particularly preferable to form the cutting groove 23 as described above without fully cutting the workpiece 11 (half cut). Examples of the workpiece 11 having a fracture toughness value of 3.0 MPa·m ^1/2 or less include single crystal silicon wafers, single crystal gallium arsenide wafers, sapphire wafers, etc. The fracture toughness value of the workpiece 11 is measured in accordance with Japanese Industrial Standard JIS R 1607 (corresponding international standard: ISO 15732).

In addition, when the cutting blade 28 is vibrated while cutting into the workpiece 11 in the first cutting step, the vibrating cutting blade 28 collides with the bottom of the cutting groove 23, and a crack is formed from the bottom of the cutting groove 23 toward the back surface 11b of the workpiece 11. This makes it easier to divide the workpiece 11 along the cutting groove 23 in the subsequent dividing step.

However, if the crack propagates and reaches the back surface 11b of the workpiece 11, there is a risk of machining defects such as chipping occurring on the back surface 11b side of the workpiece 11. Therefore, it is preferable that the cutting depth of the cutting blade 28 is set so that the crack propagating from the bottom of the cutting groove 23 does not reach the back surface 11b of the workpiece 11.

For example, the cutting depth of the cutting blade 28 is set so that the difference between the thickness of the workpiece 11 and the cutting depth of the cutting blade 28 (the difference in height between the bottom of the cutting groove 23 and the back surface 11b of the workpiece 11) is equal to or greater than half the amount of variation in the diameter of the vibrating cutting blade 28. This makes it difficult for cracks propagating from the bottom of the cutting groove 23 to reach the back surface 11b of the workpiece 11, suppressing the occurrence of processing defects.

Next, the cutting blade 28 is caused to cut into the workpiece 11 along the planned division lines 13b, thereby dividing the workpiece 11 along the planned division lines 13b (second cutting step). Figure 9 (A) is a cross-sectional view showing a portion of the workpiece 11 in the second cutting step.

In the second cutting step, first, the chuck table 22 is rotated to align the length direction of the planned division line 13b with the X-axis direction. In addition, the position of the cutting unit 26 in the Z-axis direction is adjusted so that the lower end of the cutting blade 28 is positioned below the back surface 11b (upper surface of the tape 19) of the workpiece 11 and above the holding surface 22a (lower surface of the tape 19). Furthermore, the position of the cutting unit 26 in the Y-axis direction is adjusted so that the cutting blade 28 is positioned on an extension of the planned division line 13b.

Then, while rotating the cutting blade 28, the chuck table 22 is moved along the X-axis direction. As a result, the chuck table 22 and the cutting blade 28 move relatively along the X-axis direction (machining feed), and the cutting blade 28 cuts into the workpiece 11 along the planned division line 13b.

Figure 9 (B) is a cross-sectional view showing a portion of the workpiece 11 on which a kerf (cut) 25 has been formed. When the cutting blade 28 is cut into the workpiece 11, a kerf 25 is formed along the intended division line 13b in the workpiece 11, extending from the front surface 11a to the back surface 11b, and the workpiece 11 is divided. Then, by repeating the same procedure, kerfs 25 are formed along all of the intended division lines 13b.

In the second cutting step, as in the first cutting step, the cutting blade 28 may be vibrated in the radial direction of the cutting blade 28 by the vibration imparting unit 60 (see FIG. 4). This allows the workpiece 11 to be easily divided. The vibration frequency of the cutting blade 28 and the amount of change in the diameter of the cutting blade 28 can be set in the same way as in the first cutting step.

Figure 10 is a perspective view showing the workpiece 11 after the second cutting step. As shown in Figure 10, a kerf 25 is formed in the workpiece 11 from the front surface 11a to the back surface 11b, generally parallel to the intended division line 13b.

In the second cutting step, the cutting depth of the cutting blade 28 is set so that the cutting blade 28 reaches the back surface 11b of the workpiece 11, and the cutting blade 28 collides with the back surface 11b of the workpiece 11. However, as described above, chipping that develops from the planned division line 13b is less likely to occur than chipping that develops from the planned division line 13a. Therefore, chipping that is large enough to affect the quality of the workpiece 11 is less likely to form on the back surface 11b side of the workpiece 11.

The second cutting step is performed when the workpiece 11 is not divided along the planned dividing lines 13a. Therefore, the position of the workpiece 11 is less likely to change when cutting the workpiece 11, and the workpiece 11 can be cut accurately along the planned dividing lines 13b.

In the above, the case where the same cutting blade 28 is used in the first cutting step and the second cutting step has been described (see FIG. 7(A) and FIG. 9(A)). However, the cutting blade used in the first cutting step (first cutting blade) and the cutting blade used in the second cutting step (second cutting blade) may be the same cutting blade, or may be different cutting blades with different diameters or materials.

Next, an external force is applied to the workpiece 11, and the workpiece 11 is divided along the planned division line 13a starting from the cutting groove 23 (division step). For example, if the tape 19 is an expandable tape that can be expanded by the application of an external force, an external force can be applied to the workpiece 11 by expanding the tape 19.

Figure 11 (A) is a cross-sectional view showing the workpiece 11 in the dividing step. In the dividing step, first, the frame 21 is peeled off and removed from the tape 19 as necessary. Then, the tape 19 is pulled radially outward to expand it. This applies an external force to the workpiece 11 in the radially outward direction of the workpiece 11.

When an external force is applied to the workpiece 11, the workpiece 11 breaks starting from the cutting groove 23. Specifically, a crack 27 is formed that reaches from the bottom of the cutting groove 23 to the back surface 11b of the workpiece 11, and the workpiece 11 is divided along the planned division line 13a. In other words, the cutting groove 23 functions as the division starting point (the trigger for division) of the workpiece 11.

Figure 11 (B) is a cross-sectional view showing the workpiece 11 divided into multiple chips (device chips) 29. By dividing the workpiece 11 along the planned division lines 13a, multiple chips 29, each of which includes a device 15, are manufactured. In addition, when the tape 19 is expanded, gaps are formed between adjacent chips 29, making it easier to pick up the chips 29 from the tape 19.

The dividing step is performed with the workpiece 11 divided into a plurality of pieces along the planned dividing lines 13b (see FIG. 10). Therefore, when the tape 19 is expanded, an external force is likely to be applied to each piece, and each piece is likely to break along the cutting grooves 23. As a result, the workpiece 11 is reliably divided along the cutting grooves 23.

As described above, in the chip manufacturing method according to this embodiment, the workpiece 11 is divided along the planned division line 13a by forming the cutting groove 23 and applying an external force, and the workpiece 11 is divided along the planned division line 13b by forming the kerf 25. By using this chip manufacturing method, it is possible to avoid collision between the cutting blade 28 and the back surface 11b of the workpiece 11 on the planned division line 13a, where chipping is likely to occur, and to suppress the occurrence of chipping on the back surface 11b of the workpiece 11. In addition, on the planned division line 13b, where chipping is unlikely to occur, the workpiece 11 is divided by cutting only once by the cutting blade 28, so the division process of the workpiece 11 can be simplified. This makes it possible to improve the production efficiency of the chips 29 while suppressing the occurrence of chipping.

The structure, method, etc., of this embodiment may be modified as appropriate without departing from the scope of the purpose of this invention.

(Embodiment 2)
The order of the steps included in the method for producing the tip described in the first embodiment can be changed as appropriate within the range in which it is possible to divide the workpiece 11. For example, the second cutting step can be carried out after the first cutting step and the dividing step are carried out.

Specifically, first, tape 19 is applied to the workpiece 11 (tape application step). FIG. 12 is a perspective view showing the workpiece 11 in the tape application step. In this embodiment, tape 19 is applied to the front surface 11a side of the workpiece 11. As a result, the device 15 formed on the front surface 11a side of the workpiece 11 is covered and protected by tape 19.

Next, the cutting blade 28 is caused to cut into the workpiece 11 to form a cutting groove 23 in the workpiece 11 along the intended division line 13a (first cutting step). Figure 13 (A) is a cross-sectional view showing a portion of the workpiece 11 in the first cutting step.

In this embodiment, the front surface 11a side (tape 19 side) of the workpiece 11 is held by the chuck table 22. Then, the cutting blade 28 is caused to cut into the back surface 11b side of the workpiece 11 along the planned division line 13a. As a result, a cutting groove 23 is formed on the back surface 11b side of the workpiece 11 along the planned division line 13a. When the cutting blade 28 is caused to cut into the workpiece 11, the cutting blade 28 may be vibrated by the vibration imparting unit 60 (see FIG. 4).

Figure 13 (B) is a cross-sectional view showing a part of the workpiece 11 in which the cutting grooves 23 have been formed. When the workpiece 11 has been cut along all of the planned division lines 13a, cutting grooves 23 with a depth less than the thickness of the workpiece 11 are formed along the planned division lines 13a on the back surface 11b side of the workpiece 11.

Next, an external force is applied to the workpiece 11, so that the workpiece 11 is divided along the planned division lines 13a starting from the cutting grooves 23 (division step). For example, an external force is applied to the workpiece 11 by expanding the tape 19 (see FIG. 11(A)). When an external force is applied to the workpiece 11, the workpiece 11 breaks starting from the cutting grooves 23, and is divided into a plurality of individual pieces along the planned division lines 13a (see FIG. 11(B)).

After dividing the workpiece 11 into a plurality of individual pieces, it is preferable to perform a process to return the arrangement of the workpiece 11 to the state before the tape 19 was expanded. For example, the tape 19 is heated to shrink it, so that the diameter of the tape 19 becomes the same as before the expansion.

Figure 14 is a cross-sectional view showing the workpiece 11 when the tape 19 is shrunk. When the tape 19 is shrunk, the arrangement of the workpiece 11 attached to the tape 19 returns to the state before the division step was performed. This makes it easier to cut the workpiece 11 along the planned division line 13b in the subsequent second cutting step.

Next, the tape attached to the workpiece 11 is replaced (tape replacement step). FIG. 15 is a perspective view showing the workpiece 11 in the tape replacement step. In the tape replacement step, first, tape 31 is attached to the back surface 11b side of the workpiece 11 and to the frame 21. The shape and material of tape 31 are the same as those of tape 19. For example, tape 31 includes a base material made of resin and an ultraviolet-curable resin (adhesive layer) provided on the base material.

Then, the tape 19 (see FIG. 14, etc.) is peeled off from the surface 11a side of the workpiece 11 and from the frame 21. This completes the tape replacement, and the workpiece 11 is supported by the frame 21 via the tape 31. When the tape 19 is peeled off, the cutting chips that were generated in the first cutting step described above and that adhered to the tape 19 are removed together with the tape 19. This makes it less likely that cutting chips will remain on the workpiece 11.

Next, the cutting blade 28 is caused to cut into the workpiece 11 along the planned division line 13b, thereby dividing the workpiece 11 along the planned division line 13b (second cutting step). In the second cutting step, the cutting blade 28 is caused to cut into the workpiece 11 along the planned division line 13b (see FIG. 9(A)). As a result, a kerf 25 is formed in the workpiece 11 along the planned division line 13b, from the front surface 11a to the back surface 11b (see FIG. 9(B)), and the workpiece 11 is divided into a plurality of chips 29.

When the second cutting step is performed after the dividing step, the debris generated when the workpiece 11 is broken in the dividing step is washed away by the cutting fluid supplied to the workpiece 11 in the second cutting step. This makes it difficult for debris to remain on the tip 29.

In addition, after performing the second cutting step, the first cutting step and the dividing step can also be performed. Other matters that are not described in this embodiment can be performed in the same manner as in embodiment 1.

Next, we will explain the results of evaluating the chips manufactured using the chip manufacturing method of the present invention.

Example 1
In this example, the chip according to Comparative Example 1 and the chip according to Example 1 were manufactured and compared. First, a workpiece 11 (see FIG. 2) used for manufacturing the chip was prepared. A single crystal gallium arsenide wafer (diameter 4 inches, thickness 150 μm) having orientation flats 17a and 17b (see FIG. 2) was used as the workpiece 11. Then, 52 planned division lines 13a parallel to the orientation flat 17a were set at intervals of 1.6 mm (see FIG. 2). In addition, 58 planned division lines 13b parallel to the orientation flat 17b were set at intervals of 1.6 mm (see FIG. 2).

A test wafer (single crystal gallium arsenide wafer) of the same material and shape as the workpiece 11 was prepared, and the test wafer was cut with a cutting blade 28 (see FIG. 3, etc.). The test wafer was set with planned division lines 13a and 13b, similar to the workpiece 11. The test wafer was divided (full cut) by cutting the test wafer along the planned division lines 13a and 13b with the cutting blade 28. The rotation speed of the cutting blade 28 was set to 30,000 rpm, and the processing feed speed (movement speed of the chuck table 22) was set to 10 mm/s.

The test wafer was divided into multiple chips (test chips) by the full cut described above. The back side (lower side) of the test chip was then observed, and the size of the chipping (chipping size) that had developed from the kerf (cut) formed by the cutting blade 28 was measured. Specifically, the length of the chipping (first chipping) that had developed from the kerf formed along the planned division line 13a on the back side of the test chip, in a direction perpendicular to the planned division line 13a, was measured. Similarly, the length of the chipping (second chipping) that had developed from the kerf formed along the planned division line 13b on the back side of the test chip, in a direction perpendicular to the planned division line 13b, was measured.

The chipping size measurements were performed by selecting nine test chips from the 2,600 test chips obtained by dividing the test wafer. Specifically, the first chipping and second chipping formed on the nine selected test chips were observed, and the minimum chipping size (minimum chipping size), maximum chipping size (maximum chipping size), and average chipping size (average chipping size) were measured. The minimum chipping size, maximum chipping size, and average chipping size of the first chipping and second chipping were as shown in Table 1.

As shown in Table 1, the average chipping size of the first chipping developing from the kerf formed along the planned division line 13a was more than twice as large as the average chipping size of the second chipping developing from the kerf formed along the planned division line 13b. This result confirmed that the test wafer and the workpiece 11 were crystalline wafers in which chipping developing from the planned division line 13a was more likely to occur than chipping developing from the planned division line 13b.

Next, the workpiece 11 was divided to produce chipping evaluation chips. Specifically, the two workpieces 11 were divided under different processing conditions to form the chip according to Comparative Example 1 and the chip according to Example 1.

The chip in Comparative Example 1 was formed by cutting the workpiece 11 along the intended division lines 13a and 13b with the cutting blade 28 (full cut). The rotation speed of the cutting blade 28 was set to 30,000 rpm, and the processing feed speed (movement speed of the chuck table 22) was set to 10 mm/s.

On the other hand, the chip according to Example 1 was formed by sequentially carrying out the first cutting step, the second cutting step, and the division step described in the first embodiment. Specifically, the cutting blade 28 was vibrated while cutting into the workpiece 11 to form a cutting groove 23 along the intended division line 13a (see Figs. 7(A) and 7(B)). The cutting blade 28 was vibrated so that the vibration frequency was 41 kHz and the variation in diameter of the cutting blade 28 was 5 μm. The cutting depth of the cutting blade 28 (depth of the cutting groove 23) was set to 135 μm, the rotation speed of the cutting blade 28 was set to 30,000 rpm, and the processing feed speed (movement speed of the chuck table 22) was set to 10 mm/s.

Next, the cutting blade 28 was cut into the workpiece 11 without vibrating it, cutting the workpiece 11 along the intended division line 13b (full cut, see Figures 9(A) and 9(B)). The rotation speed of the cutting blade 28 was set to 30,000 rpm, and the processing feed speed (movement speed of the chuck table 22) was set to 10 mm/s.

Then, the tape 19 was pulled to expand radially outward (see Figs. 11(A) and 11(B)). The tape expansion speed was set to 100 mm/s, and the tape expansion amount was set to 25 mm. This applied an external force to the workpiece 11, and divided the workpiece 11 into multiple chips (chips according to Example 1) starting from the cutting grooves 23.

Then, for each of the chips according to Comparative Example 1 and Example 1, the size (chipping size) of the chip (first chipping) that developed from the planned division line 13a on the back side (lower side) of the chip was measured. Specifically, the first chipping formed on the nine chips according to Comparative Example 1 was observed, and the minimum chipping size, maximum chipping size, and average chipping size were measured. Similarly, the first chipping formed on the nine chips according to Example 1 was observed, and the minimum chipping size, maximum chipping size, and average chipping size were measured. The chipping sizes of both chips were as shown in Table 2.

As shown in Table 2, the average chipping size of the chips in Example 1 was 6.9 μm, which was confirmed to be about 30% of the average chipping size (22.4 μm) of the chips in Comparative Example 1. It is presumed that this significant reduction in average chipping size is due to the fact that the workpiece 11 is divided by the first cutting step and the dividing step, thereby avoiding contact between the cutting blade 28 and the back surface 11b of the workpiece 11 on the planned dividing line 13a.

Example 2
In this example, the division rate (division success rate) was evaluated when the workpiece was divided into chips by applying an external force. First, a workpiece 11 for division evaluation was prepared. The material, dimensions, shape, etc. of the workpiece 11 used in this example were the same as those of the workpiece 11 (single crystal gallium arsenide wafer) used in Example 1. In addition, the workpiece 11 was set with division lines 13a and 13b in the same manner as in Example 1.

Next, the workpiece 11 was divided into a number of chips. Specifically, the two workpieces 11 were divided in different procedures to form the chip according to Comparative Example 2 and the chip according to Example 2.

The chip in Comparative Example 2 was formed by forming cutting grooves in the workpiece 11 along the planned division lines 13a and 13b, and then applying an external force to the workpiece 11. Specifically, first, the cutting blade 28 was vibrated while cutting into the workpiece 11, forming cutting grooves 23 (see FIG. 7B) along the planned division lines 13a and 13b. That is, in Comparative Example 2, in addition to the cutting grooves 23 (see FIG. 8) along the planned division line 13a, cutting grooves 23 were also formed along the planned division line 13b. As a result, cutting grooves 23 were formed in a lattice pattern in the workpiece 11.

The cutting blade 28 was vibrated so that the vibration frequency was 41 kHz and the variation in diameter of the cutting blade 28 was 5 μm. The cutting depth of the cutting blade 28 (depth of the cutting groove 23) was set to 135 μm, the rotation speed of the cutting blade 28 was set to 30,000 rpm, and the processing feed speed (movement speed of the chuck table 22) was set to 10 mm/s.

Then, the tape 19 was pulled to expand radially outward (see Figs. 11(A) and 11(B)). The tape expansion speed was set to 100 mm/s, and the tape expansion amount was set to 25 mm. This applied an external force to the workpiece 11, and the workpiece 11 was divided into multiple chips (chips relating to Comparative Example 2) along the planned division lines 13a and 13b starting from the cutting groove 23.

On the other hand, the chip according to Example 2 was formed by sequentially carrying out the first cutting step, the second cutting step, and the dividing step described in the first embodiment. Specifically, first, the cutting blade 28 was vibrated while cutting into the workpiece 11 to form a cutting groove 23 along the intended dividing line 13a (see Figs. 7(A) and 7(B)). The processing conditions for forming the cutting groove 23 were the same as those in Comparative Example 2.

Next, the cutting blade 28 was cut into the workpiece 11 without vibrating it, cutting the workpiece 11 along the intended division line 13b (full cut, see Figures 9(A) and 9(B)). The rotation speed of the cutting blade 28 was set to 30,000 rpm, and the processing feed speed (movement speed of the chuck table 22) was set to 10 mm/s.

Then, the tape 19 was pulled to expand radially outward (see Figs. 11(A) and 11(B)). The conditions for expanding the tape were the same as those in Comparative Example 2. As a result, an external force was applied to the workpiece 11, and the workpiece 11 was divided into multiple chips (chips according to Example 2) along the planned division lines 13a starting from the cutting grooves 23.

Then, the workpiece 11 after division was observed to confirm whether the workpiece 11 was properly divided along the planned division lines 13a, 13b. Specifically, the number of chips (divided chips) in which a gap was formed between adjacent chips was counted. The number of divided chips relative to the total number of chips (2,600 chips) was calculated as the division rate (success rate of division). The division rates of the chips according to Comparative Example 2 and Example 2 were as shown in Table 3.

As shown in Table 3, when the workpiece 11 was divided by the method according to Example 2, the chip division rate was significantly improved compared to Comparative Example 2. This improvement in the division rate is presumably due to the fact that applying an external force to the workpiece 11 in a state in which the workpiece 11 is divided into a plurality of pieces along the planned division lines 13b (see FIG. 10) makes it easier to apply an external force to each piece.

The above evaluation results confirm that by using the chip manufacturing method according to the present invention, the occurrence of chipping of the workpiece 11 is effectively suppressed and the division rate of the workpiece 11 is significantly improved.

11 Workpiece 11a Surface 11b Back surface 13a, 13b Planned division line (street)
15 Device 17a, 17b Orientation flat (cutout portion)
19 Tape 21 Frame 21a Opening 23 Cutting groove 25 Kerf (cutting edge)
27 Crack
29 Chip (Device Chip)
31 Tape 2 Cutting device 4 Base 4a, 4b Opening 6 Cassette support base 8 Cassette 10 Transport unit (transport mechanism)
10a: gripping portion 12: temporary placement area 14: guide rail 16: transport unit (transport mechanism)
18 Moving unit (moving mechanism)
18a Moving table 20 Dust-proof/water-proof cover 22 Chuck table (holding table)
22a: Holding surface 24: Clamp 26: Cutting unit 28: Cutting blade 28a: First surface 28b: Second surface 28c: Opening 30: Imaging unit 32: Cleaning unit (cleaning mechanism)
34 Transport unit (transport mechanism)
36 Display section (display unit, display device)
38 Input section (input unit, input device)
40 Control unit (control unit, control device)
42 Housing 44 Spindle 44a Threaded portion (male thread)
46 Mount 46a Opening 48 Flange portion 48a Surface 48b Convex portion 48c Through hole (slit)
50 Support shaft (boss part)
50a Threaded section (male thread)
52 Fixing nut 54 Flange (pressing flange)
54a 1st side (front)
54b Second surface (back surface)
54c Opening 54d Convex portion 54e Through hole (slit)
56 Fixing nut 58a, 58b Support member 60 Vibration imparting unit 60a, 60b Vibrator 62a, 62b Piezoelectric body 64a, 64b Electrode 66a, 66b Insulator 68a, 68b Wiring 70a, 70b, 70c, 70d Lead wire 72a, 72b Connection electrode 74 Voltage supply unit 76 Power receiving portion (power receiving unit)
78 Core 78a Recess 80 Coil (receiving coil)
82 Power supply unit (power supply unit)
84 Core 84a Recess 86 Coil (power supply coil)
88a, 88b Wiring 90 AC power supply 92 Frequency converter

Claims (7)

A method for manufacturing a plurality of chips by dividing a workpiece partitioned into a plurality of regions by a first division line and a second division line intersecting each other, the method comprising the steps of:
a first cutting step of cutting a first cutting blade into the workpiece along the first division line to form a cutting groove having a depth less than a thickness of the workpiece along the first division line;
a second cutting step of cutting the workpiece along the second planned dividing line with a second cutting blade; and
a dividing step of dividing the workpiece along the first planned dividing line starting from the cut groove by applying an external force to the workpiece. The method for manufacturing chips according to claim 1, characterized in that the workpiece is a crystalline wafer in which chips growing from the first planned division line are more likely to occur than chips growing from the second planned division line. The workpiece has an orientation flat that indicates a crystal orientation of the workpiece;
One of the first division line and the second division line is set along a direction parallel to the orientation flat,
3. The method for manufacturing a chip according to claim 2, wherein the other of the first division line and the second division line is set along a direction perpendicular to the orientation flat. The method for manufacturing a tip according to any one of claims 1 to 3, characterized in that in the first cutting step, the first cutting blade is vibrated in the radial direction of the first cutting blade at a vibration frequency in the ultrasonic band while cutting into the workpiece. A method for manufacturing a tip according to any one of claims 1 to 4, characterized in that in the second cutting step, the second cutting blade is vibrated in the radial direction of the second cutting blade at a frequency in the ultrasonic band while cutting into the workpiece. The method for manufacturing a chip according to any one of claims 1 to 5, characterized in that the second cutting step is performed after the first cutting step and before the division step. The method further includes a tape application step of applying a tape to the workpiece,
7. The method for manufacturing chips according to claim 1, wherein in the dividing step, the external force is applied to the workpiece by expanding the tape.

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