JP7051198B2 - How to make chips - Google Patents

Description

The present invention relates to a method for manufacturing a chip in which a plate-shaped workpiece is divided to manufacture a plurality of chips.

In order to divide a plate-shaped workpiece (work) represented by a wafer into multiple chips, a transmissive laser beam is focused inside the workpiece and modified by multiphoton absorption. A method for forming a modified layer (modified region) is known (see, for example, Patent Document 1). Since the modified layer is more brittle than other regions, the modified layer is formed along the planned division line (street) and then a force is applied to the workpiece to be processed from this modified layer as a starting point. You can divide an object into multiple chips.

When applying force to the work piece on which the modified layer is formed, for example, a method of attaching an expandable sheet (expand tape) to the work piece to expand it is adopted (for example, Patent Document 2). reference). In this method, usually, before irradiating a laser beam to form a modified layer on a work piece, an expand sheet is attached to the work piece, and then the modified layer is formed and then the expanded sheet is expanded. Divide the workpiece into multiple chips.

Japanese Unexamined Patent Publication No. 2002-192370 Japanese Unexamined Patent Publication No. 2010-206136

However, in the method of expanding the expanded sheet as described above, since the expanded sheet after use cannot be used again, the cost required for manufacturing the chip tends to be high. In particular, a high-performance expanded sheet in which the adhesive material does not easily remain on the chip is expensive, so that the cost required for manufacturing the chip is also high when such an expanded sheet is used.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a method for manufacturing a chip capable of dividing a plate-shaped workpiece and manufacturing a plurality of chips without using an expand sheet. It is to be.

According to one aspect of the present invention, a plurality of silicon carbide substrates having a chip region divided into a plurality of regions to be chips by a plurality of intersecting scheduled division lines and an outer peripheral surplus region surrounding the chip region on the surface. In the method for manufacturing a chip for manufacturing the chip, the holding step of directly holding the silicon carbide substrate on a holding table so that the front surface or the back surface is exposed upward, and the silicon carbide after the holding step is performed. A silicon carbide substrate along the planned division line so that the focusing point of the laser beam having a wavelength that is transparent to the substrate is located at the position of the first depth inside the silicon carbide substrate held on the holding table. The laser beam is irradiated only to the chip region of the above, the first modified layer is formed along the planned division line of the chip region, and the first modified layer is not formed in the outer peripheral surplus region. After performing the first laser processing step as a reinforcing portion, the holding step, and the first laser processing step , the condensing point of the laser beam having a wavelength that is transparent to the silicon carbide substrate is held in the holding table. The laser beam is irradiated along the planned division line so as to be positioned at the position of the second depth above the position of the first depth inside the silicon carbide substrate, and is longer than the first modified layer. After performing the second laser processing step of forming the second modified layer whose end overlaps the outer peripheral excess region along the planned division line, the first laser processing step, and the second laser processing step, the said. The unloading step of unloading the silicon carbide substrate from the holding table and the dividing step of applying a force to the silicon carbide substrate to divide the silicon carbide substrate into the individual chips after the unloading step is provided. In the dividing step, a method for manufacturing a chip is provided in which an ultrasonic vibration is applied to divide a silicon carbide substrate into individual chips.

In one aspect of the present invention, in the division step , a force may be applied to the silicon carbide substrate without removing the reinforcing portion to divide the silicon carbide substrate into individual chips . Further, in one aspect of the present invention, in the second laser processing step, the second modified layer may be formed so that the distance from the outer peripheral edge of the silicon carbide substrate to the end is 2 mm to 3 mm .

In the method for manufacturing a chip according to one aspect of the present invention, the laser is applied only to the chip region of the silicon carbide substrate so that the focusing point is positioned at the position of the first depth while the silicon carbide substrate is directly held by the holding table. The first modification layer is formed by irradiating the beam to form the first modified layer along the planned division line of the chip region, and the laser beam is irradiated so as to position the focusing point at the position of the second depth. After forming a second modified layer whose end overlaps the outer peripheral surplus region longer than the quality layer along the planned division line, ultrasonic vibration is applied to divide the silicon carbide substrate into individual chips, so that the silicon carbide is divided. There is no need to use an expand sheet to apply force to the substrate to divide it into individual chips. As described above, according to the chip manufacturing method according to one aspect of the present invention, a plurality of chips can be manufactured by dividing a silicon carbide substrate which is a plate-shaped workpiece without using an expand sheet.

Further, in the chip manufacturing method according to one aspect of the present invention, the laser beam is irradiated only to the chip region of the silicon carbide substrate to form the first modified layer along the planned division line, and the outer peripheral surplus region is first. Since the reinforcing portion is not formed with the modified layer, the chip region is reinforced by this reinforcing portion. Therefore, the silicon carbide substrate is not divided into individual chips due to the force applied during transportation or the like, and the silicon carbide substrate cannot be appropriately transported.

It is a perspective view which shows the structural example of the workpiece schematically. It is a perspective view which shows the structural example of the laser processing apparatus schematically. FIG. 3A is a cross-sectional view for explaining the holding step, and FIG. 3B is a cross-sectional view for explaining the first laser machining step and the second laser machining step. FIG. 4A is a plan view schematically showing the state of the workpiece after the modified layer is formed along all the planned division lines, and FIG. 4B is each planned division line. It is sectional drawing which shows typically the state of the modified layer formed along the above. 5 (A) and 5 (B) are cross-sectional views for explaining the reinforcing portion removing step. 6 (A) and 6 (B) are cross-sectional views for explaining the division step. It is sectional drawing for demonstrating the holding step which concerns on a modification. FIG. 8A is a cross-sectional view for explaining the division step according to the modification, and FIG. 8B is a plane schematically showing the state of the workpiece after the division step according to the modification. It is a figure.

An embodiment according to one aspect of the present invention will be described with reference to the accompanying drawings. The method for manufacturing a chip according to the present embodiment includes a holding step (see FIG. 3A), a first laser machining step (see FIGS. 3B, 4A and 4B), and a second laser machining step. Laser machining step (see FIGS. 3 (B), 4 (A) and 4 (B)), carry-out step, reinforcement removal step (see FIGS. 5 (A) and 5 (B)), and division step (see FIGS. 5 (A) and 5 (B)). 6 (A) and 6 (B)) are included.

In the holding step, the workpiece (work) having the chip region divided into a plurality of regions by the planned division line and the outer peripheral surplus region surrounding the chip region is directly held by the chuck table (holding table). In the first laser machining step, the workpiece is irradiated with a laser beam having a wavelength having transparency to form the first modified layer along the planned division line of the chip region, and the outer peripheral surplus region is first. The reinforcing part is not formed with a modified layer.

In the second laser machining step, the workpiece is irradiated with a laser beam having a wavelength having a transmissive wavelength, and the second modified layer, which is longer than the first modified layer and whose end overlaps with the outer peripheral surplus region, is used as a planned division line. Form along. In the carry-out step, the work piece is carried out from the chuck table. In the reinforcing portion removing step, the reinforcing portion is removed from the workpiece. In the dividing step, ultrasonic vibration is applied to divide the workpiece into a plurality of chips. Hereinafter, the method for manufacturing a chip according to this embodiment will be described in detail.

FIG. 1 is a perspective view schematically showing a configuration example of a workpiece (work) 11 used in the present embodiment. As shown in FIG. 1, the workpiece 11 is, for example, a semiconductor such as silicon (Si), gallium arsenide (GaAs), indium phosphate (InP), gallium nitride (GaN), silicon carbide (SiC), or sapphire. Dielectrics (insulators) such as (Al ₂ O ₃ ), soda glass, borosilicate glass, and quartz glass, or strong dielectrics (strong dielectric) such as lithium tantalate (LiTa ₃ ) and lithium niobate (LiNb ₃ ). It is a disk-shaped wafer (substrate) made of (body crystal).

The surface 11a side of the workpiece 11 is divided into a plurality of regions 15 serving as chips by a plurality of intersecting scheduled division lines (streets) 13. In the following, a substantially circular region including all of the plurality of regions 15 to be chips is referred to as a chip region 11c, and an annular region surrounding the chip region 11c is referred to as an outer peripheral surplus region 11d.

Each region 15 in the chip region 11c includes an IC (Integrated Circuit), a MEMS (Micro Electro Mechanical Systems), an LED (Light Emitting Diode), an LD (Laser Diode), a photodiode (Photodiode), and a SAW, as required. Devices such as (Surface Acoustic Wave) filters and BAW (Bulk Acoustic Wave) filters are formed.

By dividing the workpiece 11 along the scheduled division line 13, a plurality of chips can be obtained. Specifically, when the workpiece 11 is a silicon wafer, a chip that functions as a memory, a sensor, or the like can be obtained, for example. When the workpiece 11 is a gallium arsenide substrate, an indium phosphide substrate, or a gallium nitride substrate, a chip that functions as a light emitting element, a light receiving element, or the like can be obtained, for example.

When the workpiece 11 is a silicon carbide substrate, for example, a chip that functions as a power device or the like can be obtained. When the workpiece 11 is a sapphire substrate, for example, a chip that functions as a light emitting element or the like can be obtained. When the workpiece 11 is a glass substrate made of soda glass, borosilicate glass, quartz glass, or the like, for example, a chip that functions as an optical component or a cover member (cover glass) can be obtained.

When the workpiece 11 is a ferroelectric substrate (ferroelectric crystal substrate) made of a ferroelectric substance such as lithium tantalate or lithium niobate, a chip that functions as a filter, an actuator, or the like can be obtained, for example. There are no restrictions on the material, shape, structure, size, thickness, etc. of the workpiece 11. Similarly, there are no restrictions on the type, quantity, shape, structure, size, arrangement, etc. of the device formed in the region 15 to be the chip. The device may not be formed in the region 15 to be a chip.

In the chip manufacturing method according to the present embodiment, a disk-shaped silicon carbide substrate is used as the workpiece 11 to manufacture a plurality of chips. Specifically, first, a holding step of directly holding the workpiece 11 on the chuck table is performed. FIG. 2 is a perspective view schematically showing a configuration example of the laser processing apparatus used in the present embodiment.

As shown in FIG. 2, the laser processing apparatus 2 includes a base 4 on which each component is mounted. On the upper surface of the base 4, a horizontal movement mechanism for moving a chuck table (holding table) 6 for sucking and holding the workpiece 11 in the X-axis direction (machining feed direction) and the Y-axis direction (indexing feed direction). 8 is provided. The horizontal movement mechanism 8 includes a pair of X-axis guide rails 10 fixed to the upper surface of the base 4 and substantially parallel to the X-axis direction.

An X-axis moving table 12 is slidably attached to the X-axis guide rail 10. A nut portion (not shown) is provided on the back surface side (lower surface side) of the X-axis moving table 12, and an X-axis ball screw 14 substantially parallel to the X-axis guide rail 10 is screwed into this nut portion. ing.

An X-axis pulse motor 16 is connected to one end of the X-axis ball screw 14. By rotating the X-axis ball screw 14 with the X-axis pulse motor 16, the X-axis moving table 12 moves in the X-axis direction along the X-axis guide rail 10. An X-axis scale 18 for detecting the position of the X-axis moving table 12 in the X-axis direction is installed at a position adjacent to the X-axis guide rail 10.

A pair of Y-axis guide rails 20 substantially parallel to the Y-axis direction are fixed to the surface (upper surface) of the X-axis moving table 12. A Y-axis moving table 22 is slidably attached to the Y-axis guide rail 20. A nut portion (not shown) is provided on the back surface side (lower surface side) of the Y-axis moving table 22, and a Y-axis ball screw 24 substantially parallel to the Y-axis guide rail 20 is screwed into this nut portion. ing.

A Y-axis pulse motor 26 is connected to one end of the Y-axis ball screw 24. By rotating the Y-axis ball screw 24 with the Y-axis pulse motor 26, the Y-axis moving table 22 moves in the Y-axis direction along the Y-axis guide rail 20. At a position adjacent to the Y-axis guide rail 20, a Y-axis scale 28 for detecting the position of the Y-axis moving table 22 in the Y-axis direction is installed.

A support base 30 is provided on the front surface side (upper surface side) of the Y-axis moving table 22, and a chuck table 6 is arranged on the upper portion of the support base 30. The front surface (upper surface) of the chuck table 6 is a holding surface 6a that sucks and holds the back surface 11b side (or the surface 11a side) of the work piece 11 described above. The holding surface 6a is made of a porous material having high hardness, such as aluminum oxide. However, the holding surface 6a may be made of a flexible material typified by a resin such as polyethylene or epoxy.

The holding surface 6a is provided with a suction source 34 (see FIG. 3 (A), etc.) via a suction path 6b (see FIG. 3 (A), etc.) and a valve 32 (see FIG. 3 (A), etc.) formed inside the chuck table 6. It is connected to A) etc.). A rotation drive source (not shown) is provided below the chuck table 6, and the rotation drive source rotates the chuck table 6 around a rotation axis substantially parallel to the Z-axis direction.

A columnar support structure 36 is provided behind the horizontal movement mechanism 8. A support arm 38 extending in the Y-axis direction is fixed to the upper part of the support structure 36, and a wavelength having transparency to the workpiece 11 (wavelength that is difficult to be absorbed) is fixed to the tip of the support arm 38. A laser irradiation unit 40 is provided that pulsates the laser beam 17 (see FIG. 3B) of the above and irradiates the workpiece 11 on the chuck table 6.

A camera 42 that captures an image on the front surface 11a side or the back surface 11b side of the workpiece 11 is provided at a position adjacent to the laser irradiation unit 40. The image formed by imaging the workpiece 11 or the like with the camera 42 is used, for example, when adjusting the positions of the workpiece 11 and the laser irradiation unit 40.

Components such as the chuck table 6, the horizontal movement mechanism 8, the laser irradiation unit 40, and the camera 42 are connected to a control unit (not shown). The control unit controls each component so that the workpiece 11 is appropriately machined.

FIG. 3A is a cross-sectional view for explaining the holding step. In addition, in FIG. 3A, some components are shown by functional blocks. In the holding step, as shown in FIG. 3A, for example, the back surface 11b of the workpiece 11 is brought into contact with the holding surface 6a of the chuck table 6. Then, the valve 32 is opened to apply the negative pressure of the suction source 34 to the holding surface 6a.

As a result, the workpiece 11 is sucked and held by the chuck table 6 with the surface 11a side exposed upward. In this embodiment, as shown in FIG. 3A, the back surface 11b side of the workpiece 11 is directly held by the chuck table 6. That is, in the present embodiment, it is not necessary to attach the expand sheet to the workpiece 11.

After the holding step, a first laser machining step and a second laser machining step are performed in which the workpiece 11 is irradiated with a laser beam 17 having a wavelength having a transmissibility to form a modified layer along the scheduled division line 13. conduct. In this embodiment, a case where the second laser machining step is performed after the first laser machining step will be described.

FIG. 3B is a cross-sectional view for explaining the first laser machining step and the second laser machining step, and FIG. 4A shows a modified layer formed along all the scheduled division lines 13. FIG. 4B is a plan view schematically showing the state of the workpiece 11 after the machining, and FIG. 4B is a cross-sectional view schematically showing the modified layer formed along each scheduled division line 13. In addition, in FIG. 3B, some components are shown by functional blocks.

In the first laser machining step, first, the chuck table 6 is rotated so that, for example, the extending direction of the target division scheduled line 13 is parallel to the X-axis direction. Next, the chuck table 6 is moved to align the position of the laser irradiation unit 40 on the extension line of the target division scheduled line 13. Then, as shown in FIG. 3B, the chuck table 6 is moved in the X-axis direction (that is, the direction in which the target division scheduled line 13 extends).

After that, when the laser irradiation unit 40 reaches directly above one of the boundaries between the chip region 11c and the outer peripheral surplus region 11d existing at two locations on the target division scheduled line 13, the laser beam from the laser irradiation unit 40 Irradiation of 17 is started. In the present embodiment, as shown in FIG. 3B, the laser beam 17 is irradiated from the laser irradiation unit 40 arranged above the workpiece 11 toward the surface 11a of the workpiece 11.

The irradiation of the laser beam 17 is continued until the laser irradiation unit 40 reaches directly above the other boundary between the chip region 11c and the outer peripheral surplus region 11d existing at two locations on the target division scheduled line 13. That is, here, the laser beam 17 is irradiated only in the chip region 11c along the target division scheduled line 13.

Further, the laser beam 17 is irradiated so as to position the condensing point at the position of the first depth from the front surface 11a (or the back surface 11b) inside the workpiece 11. In this way, by condensing the laser beam 17 having a wavelength that is transparent to the workpiece 11 inside the workpiece 11, a part of the workpiece 11 is focused on the condensing point and its vicinity. It can be modified by polyphoton absorption to form a modified layer 19 (first modified layer 19a) that is a starting point of division (first modified layer forming step).

In the first laser machining step of the present embodiment, since the laser beam 17 is irradiated only in the chip region 11c along the target division scheduled line 13, it is modified only in the chip region 11c along the target division schedule line 13. The quality layer 19 (first modified layer 19a) is formed. That is, as shown in FIG. 4B, the modified layer 19 (first modified layer 19a) is not formed in the outer peripheral surplus region 11d in the first laser machining step.

After the first laser machining step described above, a second laser machining step is performed to form the modified layer 19 at a position different from the first depth along the same scheduled division line 13. At the stage when the first laser machining step is completed, the laser irradiation unit 40 exists on the extension line of the target division scheduled line 13, so the position of the laser irradiation unit 40 is adjusted according to the division schedule line 13. There is no need.

In the second laser machining step, first, the chuck table 6 is moved in the X-axis direction (the direction in which the target division scheduled line 13 extends). Next, the laser irradiation unit 40 starts irradiating the laser beam 17 at the timing when the laser irradiation unit 40 reaches directly above the irradiation start point set in the outer peripheral surplus region 11d of the workpiece 11.

In the present embodiment, similarly to the first laser machining step, the laser beam 17 is irradiated from the laser irradiation unit 40 arranged above the workpiece 11 toward the surface 11a of the workpiece 11. The irradiation of the laser beam 17 is continued until the laser irradiation unit 40 passes over the chip region 11c of the workpiece 11 and reaches directly above the irradiation end point set in the outer peripheral surplus region 11d.

That is, here, the laser beam 17 is irradiated to a part of the outer peripheral surplus region 11d and the chip region 11c along the target division scheduled line 13. Further, the laser beam 17 is irradiated so as to position the focusing point at a position of a second depth (a depth different from the first depth) from the front surface 11a (or the back surface 11b) inside the workpiece 11. ..

As a result, the modified layer 19 (second modified layer 19b) whose end overlaps with the outer peripheral surplus region 11d, which is longer than the modified layer 19 (first modified layer 19a) formed in the first laser machining step, is divided. It can be formed at the position of the second depth along the scheduled line 13 (second modified layer forming step). After forming the modified layer 19 (second modified layer 19b) at the position of the second depth, the modified layer is formed at the position of the first depth and the third depth different from the second depth by the same procedure. 19 (third modified layer 19c) is formed (third modified layer forming step). When forming the modified layer 19 at the position of the third depth, the positions of the irradiation start point and the irradiation end point may be changed.

In the present embodiment, one modified layer 19 (first modified layer 19a) is formed along one scheduled division line 13 in the first laser processing step, and the same one division is formed in the second laser processing step. Two modified layers 19 (second modified layer 19b and third modified layer 19c) are formed along the scheduled line 13, but the modified layer 19 is formed along one scheduled division line 13. There are no particular restrictions on the number or position of the laser.

For example, the number of the modified layers 19 formed along one scheduled division line 13 in the first laser machining step may be two or more. Further, the number of the modified layers 19 formed along the same one scheduled division line 13 in the second laser machining step may be one or three or more. That is, at least one or more modified layers 19 can be formed along one scheduled division line 13 in the first laser machining step, and one or more along one scheduled split line 13 in the second laser machining step. It suffices if the modified layer 19 can be formed.

Further, it is desirable that the modified layer 19 is formed under the condition that the crack reaches the front surface 11a (or the back surface 11b). Of course, the modified layer 19 may be formed under the condition that cracks reach both the front surface 11a and the back surface 11b. This makes it possible to divide the workpiece 11 more appropriately.

When the workpiece 11 is a silicon wafer, for example, the modified layer 19 is formed under the following conditions.
Work piece: Silicon wafer Laser beam wavelength: 1340 nm
Laser beam repetition frequency: 90 kHz
Laser beam output: 0.1W to 2W
Chuck table movement speed (machining feed speed): 180 mm / s to 1000 mm / s, typically 500 mm / s

When the workpiece 11 is a gallium arsenide substrate or an indium phosphide substrate, for example, the modified layer 19 is formed under the following conditions.
Workpiece: Gallium arsenide substrate, Indium phosphide substrate Laser beam wavelength: 1064 nm
Laser beam repetition frequency: 20 kHz
Laser beam output: 0.1W to 2W
Chuck table movement speed (machining feed speed): 100 mm / s to 400 mm / s, typically 200 mm / s

When the workpiece 11 is a sapphire substrate, the modified layer 19 is formed under the following conditions, for example.
Work piece: Sapphire substrate Laser beam wavelength: 1045 nm
Laser beam repetition frequency: 100 kHz
Laser beam output: 0.1W to 2W
Chuck table movement speed (machining feed speed): 400 mm / s to 800 mm / s, typically 500 mm / s

When the workpiece 11 is a ferroelectric substrate made of a ferroelectric substance such as lithium tantalate or lithium niobate, the modified layer 19 is formed under the following conditions, for example.
Workpiece: Lithium tantalate substrate, Lithium niobate substrate Laser beam wavelength: 532 nm
Laser beam repetition frequency: 15 kHz
Laser beam output: 0.02W to 0.2W
Chuck table movement speed (machining feed speed): 270 mm / s to 420 mm / s, typically 300 mm / s

When the workpiece 11 is a glass substrate made of soda glass, borosilicate glass, quartz glass, or the like, the modified layer 19 is formed under the following conditions, for example.
Workpiece: Soda glass substrate, borosilicate glass substrate, quartz glass substrate Laser beam wavelength: 532 nm
Laser beam repetition frequency: 50 kHz
Laser beam output: 0.1W to 2W
Chuck table movement speed (machining feed speed): 300 mm / s to 600 mm / s, typically 400 mm / s

When the workpiece 11 is a gallium nitride substrate, for example, the modified layer 19 is formed under the following conditions.
Workpiece: Gallium Nitride Substrate Laser Beam Wavelength: 532nm
Laser beam repetition frequency: 25 kHz
Laser beam output: 0.02W to 0.2W
Chuck table movement speed (machining feed speed): 90 mm / s to 600 mm / s, typically 150 mm / s

When the workpiece 11 is a silicon carbide substrate, for example, the modified layer 19 is formed under the following conditions.
Work piece: Silicon carbide substrate Laser beam wavelength: 532 nm
Laser beam repetition frequency: 25 kHz
Laser beam output: 0.02W to 0.2W, typically 0.1W
Chuck table movement speed (machining feed rate): 90 mm / s to 600 mm / s, typically 90 mm / s in the cleavage direction of the silicon carbide substrate, 400 mm / s in the non-cleavage direction.

After forming the modified layer 19 along the target division scheduled line 13, the above-mentioned first laser machining step and second laser machining step are repeated for all the remaining scheduled division lines 13. As a result, as shown in FIG. 4A, the modified layer 19 can be formed along all the planned division lines 13.

In the first laser machining step of the present embodiment, the modified layer 19 (first modified layer 19a) is formed only in the chip region 11c along the planned division line 13, and the modified layer 19 is formed in the outer peripheral surplus region 11d. Since the (first modified layer 19a) is not formed, the strength of the workpiece 11 is maintained by the outer peripheral surplus region 11d. As a result, the workpiece 11 is not divided into individual chips due to the force applied during transportation or the like. As described above, the outer peripheral surplus region 11d after the first laser machining step functions as a reinforcing portion for reinforcing the chip region 11.

Further, in the first laser machining step of the present embodiment, the modified layer 19 (first modified layer 19a) is not formed in the outer peripheral surplus region 11d, so that, for example, cracks extending from the modified layer 19 are formed on the front surface 11a and the back surface. Even in a situation where both of 11b are reached and the workpiece 11 is completely divided, each chip does not fall off or disperse. Generally, when the modified layer 19 is formed on the workpiece 11, the workpiece 11 expands in the vicinity of the modified layer 19. In the present embodiment, the expansion force generated by the formation of the modified layer 19 is applied inward in the ring-shaped outer peripheral surplus region 11d that functions as a reinforcing portion to hold down each chip and prevent it from falling off or scattering. are doing.

After the first laser machining step and the second laser machining step, a carry-out step of carrying out the workpiece 11 from the chuck table 6 is performed. Specifically, for example, a transfer unit (not shown) capable of sucking and holding the entire front surface 11a (or back surface 11b) of the workpiece 11 sucks the entire surface 11a of the workpiece 11 and then valves. 32 is closed to shut off the negative pressure of the suction source 34, and the workpiece 11 is carried out. In the present embodiment, as described above, since the outer peripheral surplus region 11d functions as a reinforcing portion, the workpiece 11 is divided into individual chips by the force applied during transportation or the like, and the workpiece 11 is divided into individual chips. It does not prevent the 11 from being properly transported.

After the carry-out step, a reinforcing portion removing step for removing the reinforcing portion from the workpiece 11 is performed. 5 (A) and 5 (B) are cross-sectional views for explaining the reinforcing portion removing step. In addition, in FIG. 5A and FIG. 5B, some components are shown by functional blocks. The reinforcing portion removing step is performed using, for example, the cutting device 52 shown in FIGS. 5 (A) and 5 (B).

The cutting device 52 includes a chuck table (holding table) 54 for sucking and holding the workpiece 11. A part of the upper surface of the chuck table 54 is a holding surface 54a that sucks and holds the chip region 11c of the workpiece 11. The holding surface 54a is connected to the suction source 58 via a suction path 54b formed inside the chuck table 54, a valve 56, and the like.

One end of a suction path 54c for sucking and holding the outer peripheral excess region 11d (that is, the reinforcing portion) of the workpiece 11 is opened in another part of the upper surface of the chuck table 54. The other end of the suction path 54c is connected to the suction source 58 via a valve 60 or the like. The chuck table 54 is connected to a rotation drive source (not shown) such as a motor, and rotates around a rotation axis substantially parallel to the vertical direction.

A cutting unit 62 is arranged above the chuck table 54. The cutting unit 62 includes a spindle 64 that is a rotation axis substantially parallel to the holding surface 54a. An annular cutting blade 66 in which abrasive grains are dispersed in a binder is mounted on one end side of the spindle 64.

A rotary drive source (not shown) such as a motor is connected to the other end side of the spindle 64, and the cutting blade 66 mounted on one end side of the spindle 64 rotates by the force transmitted from the rotary drive source. The cutting unit 62 is supported by, for example, an elevating mechanism (not shown), and the cutting blade 66 is moved in the vertical direction by the elevating mechanism.

It should be noted that on the upper surface of the chuck table 54, a relief groove for a cutting blade (not shown) for preventing contact with the cutting blade 66 is provided at a position corresponding to the boundary between the chip region 11c of the workpiece 11 and the outer peripheral surplus region 11d. ) Is formed.

In the reinforcing portion removing step, first, the back surface 11b of the workpiece 11 is brought into contact with the holding surface 54a of the chuck table 54. Then, the valves 56 and 60 are opened, and the negative pressure of the suction source 58 is applied to the holding surface 54a and the like. As a result, the workpiece 11 is sucked and held by the chuck table 54 with the surface 11a side exposed upward. In this embodiment, as shown in FIG. 5A, the back surface 11b side of the workpiece 11 is directly held by the chuck table 54. That is, again, it is not necessary to attach the expand sheet to the workpiece 11.

Next, the cutting blade 66 is rotated to cut into the boundary between the chip region 11c of the workpiece 11 and the outer peripheral surplus region 11d. At the same time, as shown in FIG. 5A, the chuck table 54 is rotated around a rotation axis substantially parallel to the vertical direction. As a result, the workpiece 11 can be cut along the boundary between the chip region 11c and the outer peripheral surplus region 11d.

After that, the valve 60 is closed to shut off the negative pressure of the suction source 58 with respect to the outer peripheral excess region 11d of the workpiece 11. Then, as shown in FIG. 5B, the outer peripheral surplus region 11d is removed from the chuck table 54. As a result, only the chip region 11c of the workpiece 11 remains on the chuck table 54.

After the reinforcing portion removing step, a division step of dividing the workpiece 11 into individual chips is performed. Specifically, ultrasonic vibration is applied to divide the workpiece 11. 6 (A) and 6 (B) are cross-sectional views for explaining the division step. In addition, in FIG. 6A and FIG. 6B, some components are shown by functional blocks.

The division step is performed using, for example, the division device 72 shown in FIGS. 6 (A) and 6 (B). The dividing device 72 includes a tank 74 in which a liquid 21 such as pure water is stored. The tank 74 is formed in a size capable of accommodating the entire workpiece 11 (chip region 11c), and an ultrasonic oscillator 76 for generating ultrasonic vibration is attached to the bottom thereof. ing.

The ultrasonic vibrator 76 includes, for example, a piezoelectric material layer made of a piezoelectric material such as barium titanate, lead zirconate titanate, lithium tantalate, and lithium niobate, and a pair of electrode layers sandwiching the piezoelectric material layer. .. An AC power source 78 for supplying AC power having a predetermined frequency is connected to the electrode layer, and the ultrasonic transducer 76 vibrates at a frequency corresponding to the frequency of the AC power supplied from the AC power source 78. do.

A holding unit 80 for holding the workpiece 11 is arranged above the tank 74. A part of the lower surface side of the holding unit 80 is a contact surface 80a in contact with the front surface 11a side (or the back surface 11b side) of the workpiece 11. It is desirable that the contact surface 80a is made of a flexible material typified by a resin such as polyethylene or epoxy.

This makes it easier to prevent damage to the device or the like formed on the surface 11a side of the workpiece 11. However, there are no particular restrictions on the material of the contact surface 80a and the like. Further, at a position surrounding the contact surface 80a, an annular protrusion 80b protruding downward is provided. As will be described later, the protrusion 80b can prevent the workpiece 11 from scattering after being divided into individual chips.

Inside the holding unit 80, a suction path 80c for transmitting a negative pressure to the workpiece 11 in contact with the contact surface 80a is provided. One end side of the suction path 80c is connected to the suction source 84 via a valve 82 or the like. The other end side of the suction path 80c is open to the contact surface 80a so that each region 15 of the workpiece 11 in contact with the contact surface 80a can be sucked. That is, the contact surface 80a is provided with a plurality of openings corresponding to each region 15.

Therefore, after the workpiece 11 is brought into contact with the contact surface 80a, the negative pressure of the suction source 84 is applied to the plurality of openings through the valve 82, the suction path 80c, etc., so that the workpiece 11 is appropriately sucked. , Can be retained. As described above, in the present embodiment, since the plurality of openings are provided at the positions corresponding to each region 15, the workpiece 11 after being divided into individual chips can be appropriately sucked and held.

In the division step according to the present embodiment, first, the contact surface 80a of the holding unit 80 is brought into contact with the surface 11a side of the workpiece 11. Next, the valve 82 is opened to apply the negative pressure of the suction source 84 to the plurality of openings. As a result, the workpiece 11 is sucked and held by the holding unit 80. Then, as shown in FIG. 6A, the holding unit 80 is positioned above the tank 74.

Then, as shown in FIG. 6B, the holding unit 80 is lowered to immerse the workpiece 11 in the liquid 21 stored in the tank 74. After the holding unit 80 is sufficiently lowered, the valve 82 is closed to shut off the negative pressure of the suction source 84. As a result, as shown in FIG. 6B, the workpiece 11 is removed from the holding unit 80.

It is desirable that the amount of lowering of the holding unit 80 is adjusted so that the gap between the bottom of the tank 74 and the lower end of the protrusion 80b is smaller than the thickness of the workpiece 11. As a result, the position of the workpiece 11 is restricted by the protrusion 80b, and it becomes possible to prevent the workpiece 11 from scattering after being divided into individual chips.

Next, AC power is supplied from the AC power source 78 to the ultrasonic vibrator 76 to vibrate the ultrasonic vibrator 76. As a result, the ultrasonic vibration generated from the ultrasonic vibrator 76 is applied to the workpiece 11 via the tank 74 and the liquid 21. Then, the crack 23 extends from the modified layer 19 of the workpiece 11 by the force of this ultrasonic vibration, and the workpiece 11 is divided into a plurality of chips 25 along the scheduled division line 13.

The conditions of ultrasonic vibration applied to the workpiece 11 are as follows, for example.
Output: 200W
Frequency: 20kHz, 28kHz
Grant time: 30 seconds to 90 seconds

However, the ultrasonic vibration conditions can be arbitrarily set within a range in which the workpiece 11 can be appropriately divided. After the workpiece 11 is divided into a plurality of chips 25, the surface 11a side of the workpiece 11 and the contact surface 80a are brought into contact with each other again to open the valve 82 and apply the negative pressure of the suction source 84. .. As a result, the workpiece 11 after being divided into the plurality of chips 25 can be sucked and held by the holding unit 80 and carried out to the outside of the tank 74.

As described above, in the chip manufacturing method according to the present embodiment, the light collecting point is set to the position of the first depth while the workpiece (work) 11 is directly held by the chuck table (holding table) 6. The laser beam 17 is irradiated only to the chip region 11c of the workpiece 11 so as to be positioned, and the modified layer 19 (first modified layer 19a) is formed along the planned division line 13 of the chip region 11c. The laser beam 17 is irradiated so as to position the focusing point at the position of the second depth and the position of the third depth, and the outer peripheral surplus region 11d is longer than the modified layer 19 formed at the position of the first depth. After forming the modified layer 19 (second modified layer 19b and third modified layer 19c) having overlapping ends along the scheduled division line 13, ultrasonic vibration is applied to form the workpiece 11 into individual chips. Since it is divided into 25 pieces, it is not necessary to use an expand sheet to apply force to the workpiece 11 to divide it into individual chips 25. As described above, according to the chip manufacturing method according to the present embodiment, a plurality of chips 25 can be manufactured by dividing a silicon carbide substrate which is a plate-shaped workpiece 11 without using an expand sheet.

Further, in the chip manufacturing method according to the present embodiment, the laser beam 17 is irradiated only to the chip region 11c of the workpiece 11, and the modified layer 19 (first modified layer 19a) along the planned division line 13 is formed. At the same time, since the outer peripheral surplus region 11d is used as a reinforcing portion on which the modified layer 19 is not formed, the chip region 11c is reinforced by this reinforcing portion. Therefore, the workpiece 11 is not divided into individual chips 25 due to the force applied during transportation or the like, and the workpiece 11 cannot be appropriately transported.

The present invention is not limited to the description of the above embodiment and can be modified in various ways. For example, in the above embodiment, the second laser machining step is performed after the first laser machining step, but the first laser machining step may be performed after the second laser machining step. Further, the order of the second modified layer forming step for forming the second modified layer 19b and the third modified layer forming step for forming the third modified layer 19c may be changed.

Further, in the above embodiment, after the first laser machining step is performed on the target one scheduled division line 13, the second laser machining step is performed on the same one scheduled split line 13. , The present invention is not limited to this aspect. For example, after performing a first laser machining step (first modified layer forming step) for forming the first modified layer 19a on a plurality of scheduled division lines 13, a second modification layer 13 is formed. Laser machining steps can also be performed.

In this case, after performing the second laser machining step (second modified layer forming step) for forming the second modified layer 19b on the plurality of scheduled division lines 13, the plurality of scheduled division lines 13 are performed. It is preferable to perform a second laser machining step (third modified layer forming step) for forming the third modified layer 19c.

More specifically, for example, first, a first modified layer forming step is performed to form the first modified layer 19a for all scheduled division lines 13 parallel to the first direction. Next, a second modified layer forming step is performed to form the second modified layer 19b for all scheduled division lines 13 parallel to the first direction. Then, a third modified layer forming step of forming the third modified layer 19c is performed on all scheduled division lines 13 parallel to the first direction.

After that, a first modified layer forming step is performed to form the first modified layer 19a for all scheduled division lines 13 parallel to the second direction different from the first direction. Next, a second modified layer forming step is performed to form the second modified layer 19b for all scheduled division lines 13 parallel to the second direction. Then, a third modified layer forming step of forming the third modified layer 19c is performed on all scheduled division lines 13 parallel to the second direction.

Also in this case, the first laser machining step (first modified layer forming step) can be performed after the second laser machining step (second modified layer forming step and third modified layer forming step). .. Similarly, the order of the second modified layer forming step for forming the second modified layer 19b and the third modified layer forming step for forming the third modified layer 19c may be changed.

Further, in the above embodiment, the back surface 11b side of the workpiece 11 is directly held by the chuck table 6 and the laser beam 17 is irradiated from the surface 11a side, but the surface 11a side of the workpiece 11 is chucked. It may be held directly on the table 6 and the laser beam 17 may be irradiated from the back surface 11b side.

FIG. 7 is a cross-sectional view for explaining a holding step according to a modified example. In the holding step according to this modification, as shown in FIG. 7, a chuck whose upper surface is formed of a porous sheet (porous sheet) 44 made of a flexible material represented by a resin such as polyethylene or epoxy, for example. It is preferable to use the table (holding table) 6.

In the chuck table 6, the upper surface 44a of the sheet 44 sucks and holds the surface 11a side of the workpiece 11. This makes it possible to prevent damage to the device or the like formed on the surface 11a side. This sheet 44 is a part of the chuck table 6 and is repeatedly used together with the main body of the chuck table 6 and the like.

However, the upper surface of the chuck table 6 does not need to be formed of the above-mentioned porous sheet 44, and is at least flexible enough not to damage the device or the like formed on the surface 11a side of the workpiece 11. It suffices if it is composed of materials. Further, it is desirable that the sheet 44 is configured to be detachable from the main body of the chuck table 6 and can be replaced when it is damaged or the like.

Further, in the above embodiment, the reinforcing portion removing step is performed after the carry-out step and before the division step. For example, after the first laser machining step and the second laser machining step and before the carry-out step, The reinforcing portion removing step may be performed.

Further, the step of removing the reinforcing portion can be omitted. In the second laser machining step of the above embodiment, the modified layer 19 (second modified layer 19b and third modified layer 19c) whose end overlaps with the outer peripheral surplus region 11d is formed along the planned division line 13. ing. Therefore, the outer peripheral surplus region 11d is more likely to be divided than in the case where the modified layer 19 and the outer peripheral surplus region 11d do not overlap. Therefore, the chip region 11c can be divided together with the outer peripheral surplus region 11d in the division step without performing the reinforcing portion removing step.

In this case, for example, the range in which the modified layer 19 is formed in the second laser machining step so that the distance from the outer peripheral edge of the workpiece 11 to the end of the modified layer 19 is about 2 mm to 3 mm. It is good to adjust. Further, for example, a groove serving as a starting point of division may be formed in the reinforcing portion before the chip region 11c is divided in the division step. FIG. 8A is a cross-sectional view for explaining the division step according to the modification, and FIG. 8B schematically shows the state of the workpiece 11 after the division step according to the modification. It is a plan view.

In the division step according to the modification, the groove serving as the starting point of division is formed by using the cutting device 52 described above before the division device 72 applies ultrasonic vibration to the workpiece 11. Specifically, as shown in FIGS. 8A and 8B, the cutting blade 66 is cut into the outer peripheral excess region 11d (that is, the reinforcing portion) to form the groove 11e which is the starting point of the division. do. It is desirable that the groove 11e is formed, for example, along the planned division line 13. By forming such a groove 11e, the workpiece 11 can be divided by the outer peripheral excess region 11d by ultrasonic vibration. In the division step according to the modification, the suction path 54c and the valve 60 of the chuck table 54 provided in the cutting device 52 can be omitted.

Further, in the division step of the above embodiment, the front surface 11a side of the workpiece 11 is sucked and held by the holding unit 80, but the back surface 11b side of the workpiece 11 may be sucked and held by the holding unit 80. good.

In addition, the structures, methods, and the like according to the above-described embodiments and modifications can be appropriately modified and implemented as long as they do not deviate from the scope of the object of the present invention.

11 Work piece (work)
11a Front surface 11b Back surface 11c Chip area 11d Outer circumference surplus area 13 Scheduled division line (street)
15 Region 17 Laser beam 19 Modified layer 19a 1st modified layer 19b 2nd modified layer 19c 3rd modified layer 21 Liquid 23 Crack 25 Chip 2 Laser processing device 4 Base 6 Chuck table (holding table)
6a Holding surface 6b Suction path 8 Horizontal movement mechanism 10 X-axis guide rail 12 X-axis movement table 14 X-axis ball screw 16 X-axis pulse motor 18 X-axis scale 20 Y-axis guide rail 22 Y-axis movement table 24 Y-axis ball screw 26 Y-axis Pulse motor 28 Y-axis scale 30 Support stand 32 Valve 34 Suction source 36 Support structure 38 Support arm 40 Laser irradiation unit 42 Camera 44 Seat (porous sheet)
44a Top surface 52 Cutting device 54 Chuck table (holding table)
54a Holding surface 54b Suction path 54c Suction path 56 Valve 58 Suction source 60 Valve 62 Cutting unit 64 Spindle 66 Cutting blade 72 Splitting device 74 Tank 76 Ultrasonic oscillator 78 AC power supply 80 Holding unit 80a Holding surface 80b Protrusion 80c Suction path 82 Valve 84 suction source

Claims (3)

Manufacture of a plurality of chips from a silicon carbide substrate having a chip region divided into a plurality of regions to be chips by a plurality of intersecting scheduled division lines and an outer peripheral surplus region surrounding the chip region on the surface. It ’s a method,
A holding step of directly holding the silicon carbide substrate on a holding table so that the front or back surface is exposed upward .
After performing the holding step, the focusing point of the laser beam having a wavelength that is transparent to the silicon carbide substrate is positioned at the position of the first depth inside the silicon carbide substrate held by the holding table. The laser beam is irradiated only to the chip region of the silicon carbide substrate along the planned division line to form a first modified layer along the planned division line of the chip region, and the outer peripheral surplus region is formed. The first laser processing step of forming the reinforcing portion in which the first modified layer is not formed, and
After performing the holding step and the first laser processing step , the first of the inside of the silicon carbide substrate in which the focusing point of the laser beam having a wavelength transparent to the silicon carbide substrate is held in the holding table. The laser beam is irradiated along the planned division line so as to be positioned at the position of the second depth above the position of the depth, and the end portion overlaps the outer peripheral excess region longer than the first modified layer. A second laser machining step of forming the modified layer along the planned division line, and
After performing the first laser machining step and the second laser machining step, a unloading step of unloading the silicon carbide substrate from the holding table and a unloading step.
After performing the carry-out step, a division step of applying a force to the silicon carbide substrate to divide the silicon carbide substrate into the individual chips is provided.
The division step is a method for manufacturing a chip, which comprises applying ultrasonic vibration to divide a silicon carbide substrate into individual chips. The method for manufacturing a chip according to claim 1, wherein in the division step , a force is applied to the silicon carbide substrate to divide the silicon carbide substrate into the individual chips without removing the reinforcing portion. The first or second aspect of the second laser machining step, wherein the second modified layer is formed so that the distance from the outer peripheral edge of the silicon carbide substrate to the edge is 2 mm to 3 mm. How to make chips.

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