JP2019197863A - Chip manufacturing method - Google Patents

Abstract

To provide a chip manufacturing method capable of manufacturing a plurality of chips by dividing a plate-like workpiece without using an expanded sheet.SOLUTION: A chip manufacturing method includes a first laser processing step, a second laser processing step, and a dividing step. The first laser processing step forms a first modified layer along division schedule lines of a chip region by irradiating only the chip region with a laser beam of a wavelength having permeability to a silicon carbide substrate along the division schedule lines. The second laser processing step forms a second modified layer along a boundary between the chip region and an outer peripheral excess region by irradiating the silicon carbide substrate with a laser beam of a wavelength having permeability to the silicon carbide substrate along the boundary. The dividing step divides the silicon carbide substrate into individual chips by applying force to the silicon carbide substrate via heating and cooling.SELECTED DRAWING: Figure 7

Description

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

  In order to divide a plate-like workpiece (workpiece) represented by a wafer into multiple chips, a laser beam with transparency 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 fragile than other regions, the modified layer is formed along the planned dividing line (street), and then a force is applied to the workpiece to process the modified layer. Objects can be divided into multiple chips.

  When applying a force to the workpiece on which the modified layer is formed, for example, a method of applying an expandable expand sheet (expanding tape) to the workpiece and expanding it is employed (for example, Patent Document 2). reference). In this method, an expanded sheet is usually attached to a workpiece before the modified layer is formed on the workpiece by irradiation with a laser beam, and then the expanded sheet is expanded after the modified layer is formed. Divide the workpiece into multiple chips.

JP 2002-192370 A JP 2010-206136 A

  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 hardly remains on the chip is expensive, and the use of such an expanded sheet increases the cost required for manufacturing the chip.

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

  According to one aspect of the present invention, a plurality of the silicon carbide substrates having a chip region partitioned into a plurality of regions that become chips by a plurality of intersecting scheduled lines and an outer peripheral surplus region surrounding the chip region are provided from the silicon carbide substrate. A chip manufacturing method for manufacturing a chip, comprising: a holding step for directly holding a silicon carbide substrate with a holding table; and a laser beam having a wavelength that is transparent to the silicon carbide substrate after the holding step is performed. The laser beam is irradiated only to the chip region of the silicon carbide substrate along the planned division line so that the focusing point is positioned inside the silicon carbide substrate held by the holding table, and the planned division of the chip region is performed. A first modified layer is formed along the line, and the first modified layer is formed in the outer peripheral surplus region. After performing the first laser processing step to be a reinforced portion and the holding step, a condensing point of a laser beam having a wavelength that is transmissive to the silicon carbide substrate is provided on the silicon carbide substrate held on the holding table. A second laser processing step of irradiating the laser beam along a boundary between the chip region and the outer peripheral surplus region so as to be positioned inside, and forming a second modified layer along the boundary; and the first laser After performing the processing step and the second laser processing step, an unloading step for unloading the silicon carbide substrate from the holding table; and after performing the unloading step, a force is applied to the silicon carbide substrate to individually separate the silicon carbide substrates. A dividing step of dividing the chip into the chips, and in the dividing step, the force is applied by heating and cooling. Chip manufacturing method of dividing the silicon carbide substrate into individual said chips Te is provided.

  In one aspect of the present invention, after the first laser processing step and the second laser processing step are performed, a reinforcing portion removing step for removing the reinforcing portion may be further included before the dividing step is performed. . In one embodiment 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 silicon carbide substrate may be held with the flexible material.

  In the method for manufacturing a chip according to one aspect of the present invention, a laser beam is irradiated only to the chip region of the silicon carbide substrate while the silicon carbide substrate is directly held by the holding table, and the first modification along the planned division line is performed. After forming a quality layer and irradiating the boundary between the chip region and the outer peripheral surplus region with a laser beam to form a second modified layer along the boundary, a force is applied by heating and cooling to form a silicon carbide substrate. Since the chip is divided into individual chips, it is not necessary to use an expanded sheet for dividing the silicon carbide substrate into individual chips by applying a force to the silicon carbide substrate. Thus, according to the chip manufacturing method of one embodiment of the present invention, a plurality of chips can be manufactured by dividing a silicon carbide substrate, which is a plate-like workpiece, without using an expanded sheet.

  In the chip manufacturing method according to one aspect of the present invention, the laser beam is irradiated only on the chip region of the silicon carbide substrate to form the first modified layer along the planned dividing line, and the outer peripheral surplus region is formed in the first region. Since the reinforcing portion is not formed with the modified layer, the tip region is reinforced by the reinforcing portion. Therefore, the silicon carbide substrate is not divided into individual chips due to the force applied at the time of conveyance or the like, and the silicon carbide substrate cannot be appropriately conveyed.

It is a perspective view which shows typically the structural example of a to-be-processed object. It is a perspective view which shows typically the structural example of a laser processing apparatus. 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 processing step. It is sectional drawing for demonstrating a 2nd laser processing step. FIG. 5A is a plan view schematically showing the state of the workpiece after the modified layer is formed, and FIG. 5B is a cross-sectional view schematically showing the state of the modified layer. It is. It is sectional drawing for demonstrating a reinforcement part removal step. It is sectional drawing for demonstrating a division | segmentation step. It is sectional drawing for demonstrating the holding | maintenance step which concerns on a modification. FIG. 9A is a cross-sectional view for explaining the dividing step according to the modified example, and FIG. 9B shows the state of the workpiece before dividing the chip region in the dividing step according to the modified example. It is a top view shown typically.

  Embodiments 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. 3A), a first laser processing step (see FIG. 3B, etc.), a second laser processing step (see FIG. 4 etc.), and carry-out. A step, a reinforcing portion removing step (see FIG. 6), and a dividing step (see FIG. 7).

  In the holding step, a workpiece (workpiece) having a chip area divided into a plurality of areas by a planned division line and an outer peripheral surplus area surrounding the chip area is directly held by a chuck table (holding table). In the first laser processing step, a laser beam having a wavelength having transparency is applied to the workpiece to form a modified layer (first modified layer) along the planned division line of the chip region, and the outer periphery. The surplus region is set as a reinforcing portion in which the modified layer is not formed.

  In the second laser processing step, a laser beam having a wavelength having transparency is applied to the workpiece, and a modified layer (second modified layer) is formed along the boundary between the chip region and the outer peripheral surplus region. . In the unloading step, the workpiece is unloaded from the chuck table. In the reinforcing portion removing step, the reinforcing portion is removed from the workpiece. In the dividing step, a workpiece is divided into a plurality of chips by applying a force by heating and cooling. Hereinafter, the manufacturing method of 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 workpiece (workpiece) 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. (Al ₂ O ₃ ), soda glass, borosilicate glass, quartz glass and other dielectrics (insulators), or ferroelectrics such as lithium tantalate (LiTa ₃ ) and lithium niobate (LiNb ₃ ) (ferroelectric) It is a disc-shaped wafer (substrate) made of a body crystal.

  The surface 11a side of the workpiece 11 is partitioned into a plurality of regions 15 that become chips by a plurality of division lines (streets) 13 that intersect. In the following description, a generally circular area including all of the plurality of areas 15 serving as chips is referred to as a chip area 11c, and an annular area surrounding the chip area 11c is referred to as an outer peripheral surplus area 11d.

  In each area 15 in the chip area 11c, 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 are provided as necessary. Devices such as (Surface Acoustic Wave) filters and BAW (Bulk Acoustic Wave) filters are formed.

  A plurality of chips can be obtained by dividing the workpiece 11 along the division line 13. Specifically, when the workpiece 11 is a silicon wafer, for example, a chip that functions as a memory, a sensor, or the like is 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 is obtained.

  When the workpiece 11 is a silicon carbide substrate, for example, a chip that functions as a power device or the like is obtained. When the workpiece 11 is a sapphire substrate, for example, a chip that functions as a light emitting element or the like is 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) is obtained.

  When the workpiece 11 is a ferroelectric substrate (ferroelectric crystal substrate) made of a ferroelectric such as lithium tantalate or lithium niobate, a chip that functions as a filter, an actuator, or the like is obtained. The material, shape, structure, size, thickness and the like of the workpiece 11 are not limited. Similarly, there is no limitation on the type, quantity, shape, structure, size, arrangement, etc. of the device formed in the region 15 to be the chip. A 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 for holding the workpiece 11 directly on the chuck table is performed. FIG. 2 is a perspective view schematically showing a configuration example of a 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 that moves 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 (index feed direction). 8 is provided. The horizontal movement mechanism 8 includes a pair of X-axis guide rails 10 that are fixed to the upper surface of the base 4 and are 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 that is 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 by 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 that are 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 rear 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 by 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. A Y-axis scale 28 for detecting the position of the Y-axis moving table 22 in the Y-axis direction is installed at a position adjacent to the Y-axis guide rail 20.

  A support table 30 is provided on the surface side (upper surface side) of the Y-axis moving table 22, and the chuck table 6 is disposed on the support table 30. The 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 workpiece 11 described above. The holding surface 6a is made of a porous material having high hardness such as aluminum oxide, for example. 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 connected to a suction source 34 (see FIG. 3 (A)) through a suction path 6b (see FIG. 3 (A), etc.) formed in the chuck table 6 and a valve 32 (see FIG. 3 (A), etc.). A) etc.). A rotation drive source (not shown) is provided below the chuck table 6, and the chuck table 6 is rotated around a rotation axis substantially parallel to the Z-axis direction by the rotation drive source.

  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 portion of the support structure 36, and a wavelength that is transmissive to the workpiece 11 (a wavelength that is difficult to be absorbed) is attached to the tip of the support arm 38. A laser irradiation unit 40 for irradiating the workpiece 11 on the chuck table 6 by pulsing the laser beam 17 (see FIG. 3B) is provided.

  At a position adjacent to the laser irradiation unit 40, a camera 42 that images the front surface 11a side or the back surface 11b side of the workpiece 11 is provided. An image formed by imaging the workpiece 11 or the like with the camera 42 is used, for example, when adjusting the position or the like 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 processed appropriately.

  FIG. 3A is a cross-sectional view for explaining the holding step. Note that in FIG. 3A, some components are illustrated as functional blocks. In the holding step, for example, the back surface 11 b of the workpiece 11 is brought into contact with the holding surface 6 a of the chuck table 6 as shown in FIG. And the valve | bulb 32 is opened and the negative pressure of the suction source 34 is made to act on the holding surface 6a.

  Thereby, the workpiece 11 is sucked and held on the chuck table 6 with the surface 11a side exposed upward. In the present embodiment, as shown in FIG. 3A, the back surface 11 b side of the workpiece 11 is held directly by the chuck table 6. That is, in this embodiment, there is no need to stick an expanded sheet to the workpiece 11.

  After the holding step, the first laser processing step of irradiating the laser beam 17 along the planned division line 13 to form a modified layer (first modified layer), and the laser beam 17 is provided on the chip region 11c and the outer peripheral surplus. Irradiation is performed along the boundary with the region 11d, and a second laser processing step is performed to form a modified layer (second modified layer). In the present embodiment, the case where the second laser processing step is performed after the first laser processing step will be described.

  3B is a cross-sectional view for explaining the first laser processing step, FIG. 4 is a cross-sectional view for explaining the second laser processing step, and FIG. 5A is a modification. FIG. 5B is a sectional view schematically showing the state of the workpiece 11 after the layer 19 is formed, and FIG. 5B is a sectional view schematically showing the modified layer 19. Note that in FIG. 3B and FIG. 4, some of the components are shown as functional blocks.

  In the first laser processing step, first, the chuck table 6 is rotated so that, for example, the direction in which the target division line 13 extends is parallel to the X-axis direction. Next, the chuck table 6 is moved, and the position of the laser irradiation unit 40 is aligned with the extension line of the target division planned 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 line 13 extends).

  After that, at the timing when the laser irradiation unit 40 arrives just above one of the boundaries between the chip area 11c and the outer peripheral surplus area 11d existing at two places on the target division line 13, the laser irradiation unit 40 processes the workpiece. Irradiation with a laser beam 17 having a wavelength having transparency to the object 11 is started. In the present embodiment, as shown in FIG. 3B, the laser beam 17 is irradiated from the laser irradiation unit 40 disposed above the workpiece 11 toward the surface 11 a of the workpiece 11.

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

  Further, the laser beam 17 is irradiated from the front surface 11a (or the back surface 11b) inside the workpiece 11 so as to position the focal point at a predetermined depth. In this way, by condensing the laser beam 17 having a wavelength that is transmissive to the workpiece 11 inside the workpiece 11, a part of the workpiece 11 is focused at and near the focal point. A modified layer 19 (modified layer 19a or the like) that is modified by multiphoton absorption and serves as a starting point of division can be formed.

  In the first laser processing step of the present embodiment, the laser beam 17 is irradiated only in the chip region 11c along the target division line 13, so that the modification is performed only in the chip region 11c along the target division line 13. A quality layer 19 is formed. That is, as shown in FIG. 5B, the modified layer 19 is not formed in the outer peripheral surplus region 11d in the first laser processing step.

  After the modified layer 19 is formed at a predetermined depth along the target division line 13, the modified layer is formed at a different depth along the target division line 13 in the same procedure. 19 is formed. In the present embodiment, as shown in FIG. 5B, for example, the modified layer 19 (modified layer 19a, modified layer) is formed at three positions having different depths from the front surface 11a (or the back surface 11b) of the workpiece 11. A quality layer 19b and a modified layer 19c) are formed.

  However, there is no particular limitation on the number and position of the modified layers 19 formed along one division line 13. For example, the number of modified layers 19 formed along one 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 the crack reaches both the front surface 11a and the back surface 11b. Thereby, the workpiece 11 can be more appropriately divided.

  After the necessary number of modified layers 19 are formed along the target division line 13, the above-described procedure is repeated, and the modified layers 19 are formed along all the other division lines 13. As shown in FIG. 5A, when the necessary number of modified layers 19 are formed along all the division lines 13, the first laser processing step is completed.

  In this first laser processing step, after the necessary number of modified layers 19 are formed along one planned division line 13, the same modified layer 19 is formed along the other divided lines 13. However, there is no particular limitation on the order in which the modified layer 19 is formed. For example, the modified layer 19 may be formed at a different depth after the modified layer 19 is formed at the same depth in all the division lines 13.

When the workpiece 11 is a silicon wafer, for example, the modified layer 19 is formed under the following conditions.
Workpiece: Silicon wafer Laser beam wavelength: 1340nm
Laser beam repetition frequency: 90 kHz
Laser beam output: 0.1 W to 2 W
Chuck table moving speed (working 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: 0.1 W to 2 W
Chuck table moving speed (machining feed speed): 100 mm / s to 400 mm / s, typically 200 mm / s

When the workpiece 11 is a sapphire substrate, for example, the modified layer 19 is formed under the following conditions.
Workpiece: Sapphire substrate Laser beam wavelength: 1045 nm
Laser beam repetition frequency: 100 kHz
Laser beam output: 0.1 W to 2 W
Chuck table moving speed (working 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 material 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: 0.02 W to 0.2 W
Chuck table moving speed (processing 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: 0.1 W to 2 W
Chuck table moving speed (processing 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: 532 nm
Laser beam repetition frequency: 25 kHz
Laser beam output: 0.02 W to 0.2 W
Chuck table moving speed (processing 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.
Workpiece: Silicon carbide substrate Laser beam wavelength: 532 nm
Laser beam repetition frequency: 25 kHz
Laser beam output: 0.02 W to 0.2 W, typically 0.1 W
Chuck table moving speed (processing feed speed): 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

  In the first laser processing step of the present embodiment, the modified layer 19 (modified layers 19a, 19b, and 19c) is formed only in the chip region 11c along the planned division line 13, and the modified outer peripheral region 11d is modified. Since the layer 19 is not formed, the strength of the workpiece 11 is maintained by the outer peripheral surplus region 11d. Thereby, the workpiece 11 is not divided into individual chips by a force applied during conveyance or the like. Thus, the outer peripheral surplus area 11 d after the first laser processing step functions as a reinforcing portion for reinforcing the chip area 11.

  In the first laser processing step of the present embodiment, 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 are covered. Even in a situation where the workpiece 11 is completely divided, each chip does not fall off and become discrete. In general, 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 inwardly in the ring-shaped outer peripheral surplus region 11d that functions as a reinforcing portion, so that each chip is pressed down, and the drop and the discrete are prevented. It is preventing.

  After the first laser processing step described above, a second laser processing step is performed. In this second laser processing step, first, the chuck table 6 is moved to align the position of the laser irradiation unit 40 on the boundary line between the chip region 11c and the outer peripheral surplus region 11d. Then, as shown in FIG. 4, the chuck table 6 is rotated while irradiating a laser beam 17 having a wavelength having transparency to the workpiece 11 from the laser irradiation unit 40. That is, in the present embodiment, the laser beam 17 is emitted from the laser irradiation unit 40 disposed above the workpiece 11 toward the surface 11 a of the workpiece 11.

  This laser beam 17 is irradiated from the front surface 11a (or the back surface 11b) inside the workpiece 11 so as to position the condensing point at a predetermined depth. In this way, by condensing the laser beam 17 having a wavelength that is transmissive to the workpiece 11 inside the workpiece 11, a part of the workpiece 11 is focused at and near the focal point. The modified layer 19 (modified layer 19d) that is modified by multiphoton absorption and serves as the starting point of the division can be formed.

  In the second laser processing step of the present embodiment, since the laser beam 17 is irradiated along the boundary between the chip region 11c and the outer peripheral surplus region 11d, the modified layer 19 is formed along this boundary. There are no particular restrictions on the number or position of the modified layers 19 formed along the boundary between the chip region 11c and the outer peripheral surplus region 11d. For example, the number of the modified layers 19 formed along the boundary may be two or more.

  The modified layer 19 along the boundary is desirably formed under the condition that the crack reaches the front surface 11a (or the back surface 11b). Of course, you may form the modified layer 19 along a boundary on the conditions that a crack reaches | attains both the surface 11a and the back surface 11b. Thereby, the workpiece 11 can be divided more appropriately, and the outer peripheral surplus region 11d can be separated from the chip region 11c.

  There are no particular restrictions on the specific conditions for forming the modified layer 19 in the second laser processing step. For example, the modified layer 19 along the boundary can be formed under the same conditions as those for forming the modified layer 19 in the first laser processing step. Of course, the modified layer 19 along the boundary may be formed under conditions different from the conditions for forming the modified layer 19 in the first laser processing step.

  As shown in FIGS. 5A and 5B, when the annular modified layer 19 (modified layer 19d) is formed along the boundary between the chip region 11c and the outer peripheral surplus region 11d, the second laser is formed. The processing step ends. In the present embodiment, the modified layer 19 (modified layer 19d) is formed at a position at the same depth as the modified layer 19 (modified layer 19b) formed in the first laser processing step. The cracks reach the front surface 11a and the back surface 11b from the modified layer 19 (modified layer 19d).

  After the first laser processing step and the second laser processing step, an unloading step for unloading the workpiece 11 from the chuck table 6 is performed. Specifically, for example, the entire surface 11a of the workpiece 11 is adsorbed by a transport unit (not shown) that can adsorb and hold the entire surface 11a (or the back surface 11b) of the workpiece 11, and then the valve. 32 is closed, the negative pressure of the suction source 34 is shut off, and the workpiece 11 is unloaded. In the present embodiment, as described above, the outer peripheral surplus region 11d functions as a reinforcing portion, so that the workpiece 11 is divided into individual chips by a force applied during conveyance or the like, and the workpiece 11 cannot be transported properly.

  After the unloading step, a reinforcing portion removing step for removing the reinforcing portion from the workpiece 11 is performed. FIG. 6 is a cross-sectional view for explaining the reinforcing portion removing step. In FIG. 6, some components are shown as functional blocks. The reinforcing portion removing step is performed using, for example, a dividing device 52 shown in FIG.

  The dividing 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 serves as a holding surface 54 a that sucks and holds the chip region 11 c of the workpiece 11. The holding surface 54 a is connected to a suction source 58 through a suction path 54 b formed in the chuck table 54, a valve 56, and the like. A heater (heating unit) 54c is disposed below the holding surface 54a.

  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. The chuck table 54 is supported by a moving mechanism (not shown), and moves in a direction substantially parallel to the holding surface 54a.

  In the reinforcing portion removing step, first, the back surface 11 b of the workpiece 11 is brought into contact with the holding surface 54 a of the chuck table 54. Then, the valve 56 is opened, and the negative pressure of the suction source 58 is applied to the holding surface 54a. Thereby, the workpiece 11 is sucked and held by the chuck table 54 with the surface 11a side exposed upward. In the present embodiment, as shown in FIG. 6, the back surface 11 b side of the workpiece 11 is held directly by the chuck table 54. That is, here again, there is no need to apply an expanded sheet to the workpiece 11.

  Next, an upward force (a force away from the holding surface 54a) is applied to the outer peripheral surplus region 11d. As described above, the modified layer 19 (modified layer 19d) serving as the starting point of the division is formed at the boundary between the chip region 11c and the outer peripheral surplus region 11d. Therefore, by applying an upward force to the outer peripheral surplus area 11d, the outer peripheral surplus area 11d can be lifted and removed from the chuck table 54 as shown in FIG. As a result, only the chip region 11 c of the workpiece 11 remains on the chuck table 54.

  After the reinforcing portion removing step, a dividing step for dividing the workpiece 11 into individual chips is performed. Specifically, the workpiece 11 is divided by generating stress by heating and cooling. FIG. 7 is a cross-sectional view for explaining the dividing step. In FIG. 7, some components are shown as functional blocks.

  The dividing step is continued using the dividing device 52. As shown in FIG. 7, the dividing device 52 further includes a nozzle (cooling unit) 60 disposed above the chuck table 54. In the dividing step of the present embodiment, after the workpiece 11 is heated by the heater 54 c provided on the chuck table 54, the cooling fluid 21 is supplied from the nozzle 60 to cool the workpiece 11. Stress necessary for dividing the workpiece 11 is generated.

  As the cooling fluid 21, for example, a liquid such as water or a gas such as air can be used. When a liquid is used as the fluid 21, the liquid may be cooled to a temperature that is low enough not to freeze (for example, a temperature that is about 0.1 ° C. to 10 ° C. higher than the freezing point). However, there are no particular restrictions on the type, flow rate, temperature, etc. of the fluid 21. For example, a low-temperature liquid such as liquid nitrogen that can further remove heat by vaporization may be used.

  When the workpiece 11 is heated by operating the heater 54 c and then the cooling fluid 21 is supplied from the nozzle 60 to cool the workpiece 11, the modified layer 19 is caused by the stress generated in the workpiece 11. Cracks 23 extend from (modified layers 19a, 19b, 19c). Thereby, the workpiece 11 is divided into a plurality of chips 25 along the scheduled division line 13.

  The heating and cooling conditions (temperature, time, etc.) are set according to the type of workpiece 11 and the like. Moreover, it is desirable that the heating of the workpiece 11 by the heater 54c and the cooling of the workpiece 11 by the liquid 21 supplied from the nozzle 60 are repeated until the workpiece 11 is appropriately divided.

  Thus, in this embodiment, the workpiece 11 can be divided into individual chips 25 by applying a necessary force by heating and cooling. In the present embodiment, the workpiece 11 is cooled after being heated, but may be heated after the workpiece 11 is cooled. There are no particular restrictions on the heating and cooling methods.

  As described above, in the chip manufacturing method according to the present embodiment, the laser beam is applied only to the chip region 11 c of the workpiece 11 while the workpiece (workpiece) 11 is directly held by the chuck table (holding table) 6. A beam 17 is irradiated to form a modified layer 19 (modified layers 19a, 19b, 19c) along the planned division line 13, and a laser beam 17 is irradiated to the boundary between the chip region 11c and the outer peripheral surplus region 11d. After forming the modified layer 19 (modified layer 19d) along the boundary, the workpiece 11 is divided into individual chips 25 by applying a force by heating and cooling. Therefore, it is not necessary to use an expanded sheet to divide into individual chips 25. Thus, according to the chip manufacturing method according to the present embodiment, a plurality of chips 25 can be manufactured by dividing the silicon carbide substrate that is the plate-like workpiece 11 without using an expanded sheet.

  Further, in the chip manufacturing method according to the present embodiment, the modified layer 19 (modified layers 19a, 19b, and 19c) along the division line 13 is irradiated with the laser beam 17 only on the chip region 11c of the workpiece 11. In addition, the outer peripheral surplus region 11d is used as a reinforcing portion in which the modified layer 19 (modified layers 19a, 19b, 19c) is not formed, so that the chip region 11c is reinforced by this reinforcing portion. Therefore, the workpiece 11 is not divided into the individual chips 25 due to the force applied during conveyance, and the workpiece 11 cannot be conveyed properly.

  In addition, this invention is not restrict | limited to description of the said embodiment etc., A various change can be implemented. For example, in the above embodiment, the second laser processing step is performed after the first laser processing step. However, the first laser processing step may be performed after the second laser processing step. Further, the second laser processing step can be performed in the middle of the first laser processing step.

  In the above embodiment, the back surface 11 b side of the workpiece 11 is held directly by the chuck table 6 and the laser beam 17 is irradiated from the front surface 11 a side, but the front surface 11 a side of the workpiece 11 is chucked. The laser beam 17 may be irradiated from the back surface 11b side by holding the table 6 directly.

  FIG. 8 is a cross-sectional view for explaining a holding step according to a modification. In the holding step according to this modified example, as shown in FIG. 8, for example, a chuck whose upper surface is constituted by a porous sheet (porous sheet) 44 made of a flexible material typified by a resin such as polyethylene or epoxy. A table (holding table) 6 may be used.

  In the chuck table 6, the upper surface 44 a of the sheet 44 sucks and holds the surface 11 a side of the workpiece 11. Thereby, damage of the device etc. currently formed in the surface 11a side can be prevented. The 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 configured by the porous sheet 44 described above, and is flexible enough to at least not damage a device or the like formed on the surface 11a side of the workpiece 11. What is necessary is just to be comprised with the material. 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.

  Moreover, in the said embodiment, although the reinforcement part removal step is performed after the unloading step and before the dividing step, for example, after the first laser processing step and the second laser processing step and before the unloading step, You may perform a reinforcement part removal step. In addition, when performing a reinforcement part removal step after a carrying-out step and before a division | segmentation step, since it is not necessary to convey the workpiece 11 after a reinforcement part removal step, the workpiece 11 can be conveyed appropriately. It is easy to avoid problems such as disappearance.

  Similarly, the reinforcing part removing step can be performed after the dividing step. In this case, since the chip region 11c and the outer peripheral surplus region 11d are more reliably divided by the thermal shock applied in the dividing step, the reinforcing portion can be more easily removed in the subsequent reinforcing portion removing step.

  Further, the reinforcing portion removing step can be omitted. In this case, for example, a range in which the modified layer 19 is formed in the first laser processing step and the second laser processing step so that the width of the reinforcing portion is about 2 mm to 3 mm from the outer peripheral edge of the workpiece 11. Adjust it. Further, for example, before dividing the chip region 11c in the dividing step, a groove serving as a starting point of the division may be formed in the reinforcing portion.

  FIG. 9A is a cross-sectional view for explaining the dividing step according to the modified example, and FIG. 9B is a state of the workpiece before dividing the chip region 11c in the dividing step according to the modified example. It is a top view which shows typically. In the dividing step according to the modified example, before the workpiece 11 is divided into individual chips by the dividing device 52, for example, using the cutting unit 62 provided in the dividing device 52, Forming a groove.

  The cutting unit 62 includes a spindle (not shown) that serves as a rotation axis substantially parallel to the holding surface 54a. An annular cutting blade 64 in which abrasive grains are dispersed in a binder is attached to one end of the spindle. A rotation drive source (not shown) such as a motor is connected to the other end side of the spindle, and the cutting blade 64 mounted on the one end side of the spindle is rotated by a force transmitted from the rotation drive source. For example, the cutting unit 62 is supported by an elevating mechanism (not shown), and the cutting blade 64 is moved in the vertical direction by the elevating mechanism.

  As shown in FIGS. 9A and 9B, when forming the groove to be the starting point of the division, for example, the cutting blade 64 described above is rotated and the outer peripheral surplus region 11d (that is, the reinforcing portion). To cut into. Thereby, the groove | channel 11e used as the starting point of a division | segmentation can be formed in a reinforcement part. The groove 11e is preferably formed along the planned division line 13, for example. By forming such a groove 11e, the tip region 11c of the workpiece 11 can be divided together with the outer peripheral surplus region 11d.

  In addition, the structures, methods, and the like according to the above-described embodiments and modifications can be appropriately changed and implemented without departing from the scope of the object of the present invention.

11 Workpiece (work)
11a Front surface 11b Back surface 11c Chip region 11d Peripheral surplus region 13 Scheduled line (street)
15 region 17 laser beam 19, 19a, 19b, 19c, 19d modified layer 21 fluid 23 crack 25 chip 2 laser processing apparatus 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 base 32 Valve 34 Suction source 36 Support structure 38 Support arm 40 Laser irradiation unit 42 Camera 44 Sheet (porous sheet)
44a Upper surface 52 Dividing device 54 Chuck table (holding table)
54a Holding surface 54b Suction path 54c Heater (heating unit)
56 Valve 58 Suction source 60 Nozzle (cooling unit)
62 cutting unit 64 cutting blade

Claims (3)

A chip manufacturing method for manufacturing 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 lines and an outer peripheral surplus region surrounding the chip region. There,
A holding step for holding the silicon carbide substrate directly on the holding table;
After carrying out the holding step, along the planned dividing line, the condensing point of the laser beam having a wavelength transmissive to the silicon carbide substrate is positioned 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 to form a first modified layer along the planned division line of the chip region, and the first modified layer is formed in the outer peripheral surplus region. A first laser processing step as a non-reinforced portion;
After performing the holding step, the chip region and the outer peripheral surplus are positioned so that a condensing point of a laser beam having a wavelength transmissive to the silicon carbide substrate is positioned inside the silicon carbide substrate held by the holding table. A second laser processing step of irradiating the laser beam along a boundary with the region and forming a second modified layer along the boundary;
An unloading step of unloading the silicon carbide substrate from the holding table after performing the first laser processing step and the second laser processing step;
Dividing the silicon carbide substrate into individual chips by applying a force to the silicon carbide substrate after performing the unloading step; and
In the dividing step, the force is applied by heating and cooling to divide the silicon carbide substrate into the individual chips.   2. The method according to claim 1, further comprising a reinforcing portion removing step of removing the reinforcing portion after performing the first laser processing step and the second laser processing step and before performing the dividing step. Chip manufacturing method. The upper surface of the holding table is made of a flexible material,
3. The chip manufacturing method according to claim 1, wherein in the holding step, the surface side of the silicon carbide substrate is held by the flexible material.