JP6925717B2 - Chip manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a chip, which manufactures a plurality of chips by dividing a plate-shaped workpiece.

In order to divide a plate-shaped workpiece (work) represented by a wafer into a plurality of chips, a transmissive laser beam is focused inside the workpiece and modified by multiphoton absorption. A method of 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 starting from this modified layer. You can divide things into multiple chips.

When applying force to the work piece on which the modified layer is formed, for example, a method of attaching an stretchable expanding sheet (expanding 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 a modified layer is formed and then the expanded sheet is expanded. The work piece is divided into a plurality of 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, and therefore, using such an expanded sheet also increases the cost required for manufacturing the chip.

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, from a plate-shaped workpiece 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. A method for manufacturing a plurality of chips, in which a holding step of directly holding the workpiece directly on a holding table and a wavelength having a wavelength that is transparent to the workpiece after the holding step is performed. The laser beam is irradiated only to the chip region of the workpiece along the planned division line so that the focusing point of the laser beam is positioned inside the workpiece held on the holding table, and the chip region of the chip region is irradiated with the laser beam. A laser processing step in which a modified layer is formed along the planned division line and the outer peripheral surplus region is a reinforcing portion in which a modified layer is not formed, and after performing the laser processing step, from the holding table After carrying out the carry-out step of carrying out the work piece, the reinforcing part removing step of holding the work piece on the chuck table and removing the reinforcing part after carrying out the carrying-out step, and carrying out the reinforcing part removing step. A division step of applying a force to the workpiece held by the chuck table to divide the workpiece into individual chips is provided, and in the division step, the force is applied by one cooling or heating. A method for manufacturing a chip is provided, which divides the workpiece into the individual chips.

In one aspect of the present invention, the upper surface of the holding table is made of a flexible material, and in the holding step, the surface side of the workpiece may be held by the flexible material.

The chip manufacturing method according to an embodiment of the present invention, while directly held by the holding table a workpiece, a modified layer along the dividing lines by irradiating a laser beam only in the chip region of the workpiece An expanding sheet is used to apply force to the workpiece to divide it into individual inserts, as it is formed and then subjected to force by one cooling or heating to divide the workpiece into individual inserts. No need. As described above, according to the method for producing chips according to one aspect of the present invention, a plurality of chips can be produced by dividing a plate-shaped workpiece without using an expanding sheet.

Further, in the chip manufacturing method according to one aspect of the present invention, the modified layer is formed by irradiating only the chip region of the workpiece with a laser beam along the planned division line, and the modified layer forms the outer peripheral surplus region. Since the reinforcing portion is not formed, the chip region is reinforced by this reinforcing portion. Therefore, the work piece is not divided into individual chips due to the force applied during transportation or the like, and the work piece cannot be properly conveyed.

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 laser machining step. FIG. 4A is a plan view schematically showing the state of the workpiece after the laser machining step, and FIG. 4B schematically shows the state of the workpiece after the laser machining step. It is sectional drawing which shows. 5 (A) and 5 (B) are cross-sectional views for explaining the reinforcing portion removing step. It is sectional drawing for demonstrating the division step. It is sectional drawing for demonstrating the holding step which concerns on a modification. FIG. 8 (A) is a cross-sectional view for explaining the division step according to the modified example, and FIG. 8 (B) shows the state of the workpiece before dividing the chip region in the divided step according to the modified example. It is a top view schematically shown.

An embodiment according to one aspect of the present invention will be described with reference to the accompanying drawings. The chip manufacturing method according to the present embodiment includes a holding step (see FIG. 3 (A)), a laser machining step (see FIGS. 3 (B), 4 (A) and 4 (B)), an unloading step, and reinforcement. A partial removal step (see FIGS. 5 (A) and 5 (B)) and a division step (see FIG. 6) 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 laser processing step, the workpiece is irradiated with a laser beam having a wavelength having transparency to form a modified layer (modified region) along the planned division line in the chip region, and the outer peripheral surplus region is modified. Reinforcement part where no layer is formed.

In the carry-out step, the work piece is carried out from the holding table. In the reinforcing portion removing step, the reinforcing portion is removed from the workpiece. In the dividing step, a force is applied by one cooling or heating to divide the workpiece into a plurality of chips. Hereinafter, the method for manufacturing the chip according to the present embodiment will be described in detail.

FIG. 1 is a perspective view schematically showing a configuration example of a work piece (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 phosphide (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 planned division lines (streets) 13. In the following, a substantially circular region including all of the plurality of regions 15 serving as 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.

In each region 15 in the chip region 11c, if necessary, IC (Integrated Circuit), MEMS (Micro Electro Mechanical Systems), LED (Light Emitting Diode), LD (Laser Diode), photodiode (Photodiode), SAW 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, for example, a chip that functions as a memory, a sensor, or the like can be obtained. When the workpiece 11 is a gallium arsenide substrate, an indium phosphide substrate, or a gallium nitride substrate, for example, a chip that functions as a light emitting element, a light receiving element, or the like can be obtained.

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, for example, a chip that functions as a filter, an actuator, or the like can be obtained. 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 the chip.

In the chip manufacturing method according to the present embodiment, a disk-shaped silicon wafer is used as the workpiece 11, and a plurality of chips are manufactured. 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 the 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. At a position adjacent to 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.

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 the 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 front 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 (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 (wavelength that is difficult to be absorbed) that is transparent to the workpiece 11 is attached to the tip of the support arm 38. A laser irradiation unit 40 is provided that oscillates the laser beam 17 (see FIG. 3B) of the above (see FIG. 3B) to irradiate the workpiece 11 on the chuck table 6.

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

After the holding step, a laser processing step is performed in which the workpiece 11 is irradiated with a laser beam 17 having a wavelength having transparency to form a modified layer along the scheduled division line 13. FIG. 3B is a cross-sectional view for explaining the laser machining step, and FIG. 4A is a plan view schematically showing the state of the workpiece 11 after the laser machining step. 4 (B) is a cross-sectional view schematically showing the state of the workpiece 11 after the laser machining step. In FIG. 3B, some components are shown by functional blocks.

In the 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 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 just 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 a condensing point at a predetermined depth from the inner surface 11a (or back surface 11b) of 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 at the condensing point and its vicinity. It can be modified by multiphoton absorption to form a modified layer (modified region) 19 which is a starting point of division. In the present embodiment, since the laser beam 17 is irradiated only in the chip region 11c along the target division scheduled line 13, the modified layer 19 is formed only in the chip region 11c along the target division schedule line 13. NS.

After the modified layer 19 is formed at a predetermined depth along the target split line 13, the modified layer 19 is formed at a different depth along the target split line 13 in the same procedure. 19 is formed. Specifically, for example, as shown in FIG. 4B, the modified layer 19 (first modified layer 19a) is located at three positions where the depths of the workpiece 11 from the front surface 11a (or the back surface 11b) are different. , Second modified layer 19b, third modified layer 19c).

However, there is no particular limitation on the number and positions of the modified layers 19 formed along one scheduled division line 13. For example, the number of modified layers 19 formed along one scheduled division line 13 may be one. 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 moving speed (machining feed rate): 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, the modified layer 19 is formed under the following conditions, for example.
Work piece: 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 moving speed (machining feed rate): 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 moving speed (machining feed rate): 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.
Work piece: 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 moving speed (machining feed rate): 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 moving speed (machining feed rate): 300 mm / s to 600 mm / s, typically 400 mm / s

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

When the workpiece 11 is a silicon carbide substrate, the modified layer 19 is formed under the following conditions, for example.
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 moving 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 required number of modified layers 19 along the target planned division line 13, the above operation is repeated to form the modified layer 19 along all the other planned division lines 13. As shown in FIG. 4A, the laser machining step ends when the modified layer 19 is formed along all the scheduled division lines 13.

In the present embodiment, the modified layer 19 is formed only in the chip region 11c along the planned division line 13, and the modified layer 19 is not formed in the outer peripheral surplus region 11d. The strength of 11 is maintained. 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 laser machining step functions as a reinforcing portion for reinforcing the chip region 11 on which the modified layer 19 is formed.

Further, in the present embodiment, since the modified layer 19 is not formed in the outer peripheral surplus region 11d, for example, cracks extending from the modified layer 19 reach both the front surface 11a and the back surface 11b, and the workpiece 11 is completely formed. Even in the divided situation, 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. doing.

After the laser machining step, a unloading step of unloading 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 opened 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 of 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 dividing device 52 shown in FIGS. 5 (A) and 5 (B).

The dividing device 52 includes a chuck 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.

Further, 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 moves in the vertical direction by the elevating mechanism.

A relief groove for a cutting blade (not shown) is provided on the upper surface of the chuck table 54 at a position corresponding to the boundary between the chip region 11c of the workpiece 11 and the outer peripheral surplus region 11d to prevent contact with the cutting blade 66. ) 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, for example, a large temperature difference is formed inside the workpiece 11 (between the front surface 11a and the back surface 11b), and a force is applied by a thermal shock to divide the workpiece 11. .. FIG. 6 is a cross-sectional view for explaining the division step. In FIG. 6, some components are shown by functional blocks.

The division step is subsequently performed using the division device 52. As shown in FIG. 6, the dividing device 52 further includes an injection nozzle (temperature difference forming unit) 68 arranged above the chuck table 54. In the division step of the present embodiment, the cooling fluid 21 is sprayed from the injection nozzle 68 onto the surface 11a of the workpiece 11, to form a temperature difference required for generating a thermal shock. However, the temperature difference required for the generation of thermal shock may be formed by spraying the heating fluid 21.

As the cooling fluid 21, for example, a low-temperature liquid such as liquid nitrogen, which can further remove heat by vaporization, may be used. As a result, the surface 11a side of the workpiece 11 is quickly cooled, and the required temperature difference can be easily formed. Here, the required temperature difference means a temperature difference at which a thermal shock exceeding the stress required for breaking the workpiece 11 along the modified layer 19 can be obtained. This temperature difference is determined, for example, according to the material and thickness of the workpiece 11, the state of the modified layer 19, and the like.

However, there are no particular restrictions on the type and flow rate of the fluid 21. For example, a sufficiently cooled gas such as air or a liquid such as water can be used. When a liquid is used as the fluid 21, it is preferable to cool the liquid to a temperature low enough not to freeze (for example, a temperature higher than the freezing point by about 0.1 ° C. to 10 ° C.).

When the workpiece 11 is cooled so that a sufficient temperature difference is formed, cracks 23 extend from the modified layer 19 due to thermal shock, and the workpiece 11 extends to a plurality of chips 25 along the planned division line 13. It is divided. As described above, in the present embodiment, the required force can be applied by one cooling, and the workpiece 11 can be divided into individual chips 25. In the present embodiment, the thermal shock is generated by rapidly cooling the workpiece 11, but the thermal shock may be generated by rapidly heating the workpiece 11.

As described above, in the chip manufacturing method according to the present embodiment, the work piece (work) 11 is directly held by the chuck table (holding table) 6, and the laser is applied only to the chip region 11c of the work piece 11. The beam 17 is irradiated to form a modified layer 19 along the scheduled division line 13, and then a force is applied by one cooling to divide the workpiece 11 into individual chips 25, so that the workpiece 11 is divided. It is not necessary to use an expanding sheet to apply force to the chips and divide them 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 wafer 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, to form the modified layer 19 along the planned division line 13, and the outer peripheral surplus region 11d is formed. Since the reinforcing portion in which the modified layer 19 is not formed is used, 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 implemented with various modifications. For example, in the holding step of 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 of the workpiece 11 is irradiated. The side may be directly held by the chuck 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 the holding step according to the modified example. In the holding step according to this modification, as shown in FIG. 7, a chuck whose upper surface is formed of, for example, a porous sheet (porous sheet) 44 made of a flexible material typified by a resin such as polyethylene or epoxy. 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 have 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 so that it can be attached to and detached from the main body of the chuck table 6 and can be replaced when it is damaged.

Further, in the above embodiment, the reinforcing portion removing step is performed after the carrying-out step and before the dividing step. However, for example, the reinforcing portion removing step may be performed after the laser machining step and before the carrying-out step. good. When the reinforcing portion removing step is performed after the carry-out step and before the dividing step, it is not necessary to transport the workpiece 11 after the reinforcing portion removing step, so that the workpiece 11 can be appropriately conveyed. It is easy to avoid problems such as disappearance.

Further, the step of removing the reinforcing portion can be omitted. In this case, for example, the range in which the modified layer 19 is formed in the laser machining step may be adjusted so that the width of the reinforcing portion is about 2 mm to 3 mm from the outer peripheral edge of the workpiece 11. Further, for example, before dividing the chip region 11c in the division step, a groove serving as a starting point of division may be formed in the reinforcing portion. FIG. 8 (A) is a cross-sectional view for explaining the division step according to the modified example, and FIG. 8 (B) shows the workpiece 11 before dividing the chip region 11c in the divided step according to the modified example. It is a top view which shows the state schematically.

In the division step according to the modified example, 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), and the groove serving as the starting point of division is formed. Form 11e. 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 into the outer peripheral excess region 11d by thermal shock. In the division step according to the modified example, the suction path 54c of the chuck table 54, the valve 60, and the like can be omitted.

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 regions 17 Laser beam 19 Modified layer (modified region)
19a 1st modified layer 19b 2nd modified layer 19c 3rd modified layer 21 Fluid 23 Crack 25 Chip 2 Laser machining equipment 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 (Porus seat)
44a Top surface 52 Splitting 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 68 Injection nozzle (Temperature difference forming unit)

Claims (2)

A chip for producing a plurality of chips from a plate-shaped workpiece 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. It ’s a manufacturing method,
A holding step that holds the work piece directly on the holding table,
After performing the holding step, along the planned division line so as to position the focusing point of the laser beam having a wavelength that is transparent to the work piece inside the work piece held on the holding table. The laser beam is irradiated only to the chip region of the work piece to form a modified layer along the planned division line of the chip region, and a reinforcing portion in which the modified layer is not formed in the outer peripheral surplus region. Laser processing steps and
After performing the laser machining step, a unloading step of unloading the workpiece from the holding table and a unloading step.
After performing the carry-out step, a reinforcing portion removing step of holding the workpiece on a chuck table and removing the reinforcing portion, and a reinforcing portion removing step.
After performing the reinforcing portion removing step , a division step of applying a force to the workpiece held by the chuck table to divide the workpiece into individual inserts is provided.
In the dividing step, a method for producing a chip is characterized in that the force is applied by one cooling or heating to divide the workpiece into individual chips. The upper surface of the holding table is made of a flexible material.
The method for producing a chip according to claim 1, wherein in the holding step, the surface side of the work piece is held by the flexible material.

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