WO2020129569A1 - Laser machining method, semiconductor member production method, and semiconductor object - Google Patents

Laser machining method, semiconductor member production method, and semiconductor object Download PDF

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Publication number
WO2020129569A1
WO2020129569A1 PCT/JP2019/046656 JP2019046656W WO2020129569A1 WO 2020129569 A1 WO2020129569 A1 WO 2020129569A1 JP 2019046656 W JP2019046656 W JP 2019046656W WO 2020129569 A1 WO2020129569 A1 WO 2020129569A1
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Prior art keywords
modified
semiconductor
region
crack
virtual
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PCT/JP2019/046656
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French (fr)
Japanese (ja)
Inventor
敦之 田中
千秋 笹岡
天野　浩
大祐 河口
陽太郎 和仁
泰則 伊ケ崎
Original Assignee
国立大学法人東海国立大学機構
浜松ホトニクス株式会社
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Publication of WO2020129569A1 publication Critical patent/WO2020129569A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/50—Working by transmitting the laser beam through or within the workpiece
    • B23K26/53—Working by transmitting the laser beam through or within the workpiece for modifying or reforming the material inside the workpiece, e.g. for producing break initiation cracks
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28D—WORKING STONE OR STONE-LIKE MATERIALS
    • B28D5/00—Fine working of gems, jewels, crystals, e.g. of semiconductor material; apparatus or devices therefor
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
    • H01L21/304—Mechanical treatment, e.g. grinding, polishing, cutting

Definitions

  • One aspect of the present invention relates to a laser processing method, a semiconductor member manufacturing method, and a semiconductor object.
  • a modified region is formed inside the semiconductor object, and a processing method for cutting a semiconductor member such as a semiconductor wafer from the semiconductor object along the modified region is a method. It is known (for example, see Patent Documents 1 and 2).
  • the method of forming the modified region greatly affects the state of the obtained semiconductor member.
  • One aspect of the present invention is to provide a laser processing method, a semiconductor member manufacturing method, and a semiconductor object that enable suitable acquisition of a semiconductor member.
  • a laser processing method a plurality of modified spots and a plurality of modified spots inside the semiconductor object by causing a laser beam to enter the inside of the semiconductor object from the surface of the semiconductor object.
  • a peripheral region that prevents cracks from propagating from the modified region to the outer surface of the semiconductor object is provided in the semiconductor object so as to surround the modified region.
  • the first step it is possible to prevent the crack from propagating from the modified region to the outer surface of the semiconductor object by the peripheral region, and the gas contained in the modified region escapes to the outside through the crack. It can be suppressed. Therefore, it is possible to effectively increase or maintain the gas pressure (internal pressure). As a result, it is possible to easily form a crack across the virtual surface by using the internal pressure. By obtaining the semiconductor member from the semiconductor object with the crack extending over the virtual surface as the boundary, it is possible to obtain a suitable semiconductor member.
  • the peripheral area may have a frame shape surrounding the modified area when viewed from the direction facing the surface.
  • the material of the semiconductor object may include nitride.
  • the first step it is possible to decompose the semiconductor object and generate nitrogen gas by making laser light enter the inside of the semiconductor object.
  • the laser processing method may include a step of forming a hole in the peripheral area for allowing gas to escape to the outside. According to this, when strain is applied to the semiconductor object due to the increase in gas pressure, the gas can be released to the outside and the strain can be suppressed.
  • a semiconductor member manufacturing method is a manufacturing method including the laser processing method described above, and includes a second step of acquiring a semiconductor member from a semiconductor object with a crack across a virtual surface as a boundary.
  • the laser processing method since the laser processing method is included, it is possible to prevent the gas contained in the modified region from escaping to the outside through the cracks, and the gas pressure (internal pressure) is effectively reduced. It is possible to raise or maintain it. By utilizing the internal pressure, it becomes possible to easily form a crack over the virtual surface. By obtaining the semiconductor member from the semiconductor object with the crack extending over the virtual surface as the boundary, it is possible to obtain a suitable semiconductor member.
  • a plurality of virtual surfaces are set so as to be aligned in a direction facing the surface, and a plurality of modified regions and peripheral regions are provided corresponding to each of the plurality of virtual surfaces.
  • the peripheral region may prevent the propagation of cracks from the surrounding modified region to another modified region adjacent to the modified region. According to this, a plurality of semiconductor members can be obtained from one semiconductor object. Further, since the cracks are prevented from propagating from the reforming region to the other reforming regions by the peripheral region, it is possible to prevent the gas from escaping from the reforming region to the other reforming region, It is possible to effectively increase or maintain the gas pressure.
  • the semiconductor object may be a semiconductor ingot, and the semiconductor member may be a semiconductor wafer. According to this, it becomes possible to obtain a plurality of semiconductor wafers from one semiconductor ingot.
  • a plurality of virtual surfaces are set so as to be aligned in the direction in which the surface extends, and a plurality of modified regions and peripheral regions are provided corresponding to each of the plurality of virtual surfaces.
  • the peripheral region which is provided, may prevent a crack from propagating from the surrounding modified region to another modified region adjacent to the modified region. According to this, a plurality of semiconductor members can be obtained from one semiconductor object. Further, since the cracks are prevented from propagating from the reforming region to the other reforming regions by the peripheral region, it is possible to prevent the gas from escaping from the reforming region to the other reforming region, It is possible to effectively increase or maintain the gas pressure.
  • the semiconductor object may be a semiconductor wafer, and the semiconductor member may be a semiconductor device. This makes it possible to obtain one semiconductor wafer or a plurality of semiconductor devices.
  • the semiconductor member manufacturing method may include, after the first step, a step of heating the semiconductor object to expand the gas and propagate the crack along the virtual surface. .. In this case, it is possible to reliably form a crack across the virtual surface.
  • a part of the semiconductor object in the second step, may be peeled off along the virtual surface by applying a stimulus to the modified region from the outside. According to this, while releasing the pressure of the gas in the reforming region, a part of the semiconductor object can be peeled off by also utilizing this released force.
  • a peripheral region may be removed from the semiconductor object to peel off a part of the semiconductor object along the virtual surface. According to this, while releasing the pressure of the gas in the reforming region, a part of the semiconductor object can be peeled off by also utilizing this released force.
  • a semiconductor object is a semiconductor object having a surface, and inside the semiconductor object, a modified region formed along a virtual surface facing the surface and a modified region are provided.
  • a peripheral region provided so as to surround the reforming region includes a plurality of reforming spots and a plurality of cracks and gases respectively extending from the plurality of reforming spots, and the reforming spot is formed in the peripheral region. The undeformed region prevents the propagation of cracks from the surrounding modified region to the outer surface of the semiconductor object.
  • a crack is prevented from propagating from the modified region to the outer surface of the semiconductor object by the peripheral region, and the gas contained in the modified region is exposed to the outside through the crack.
  • the escape is suppressed. Therefore, it is possible to effectively increase or maintain the gas pressure (internal pressure).
  • internal pressure By utilizing the internal pressure, it becomes possible to accurately propagate the crack along the virtual surface. Therefore, by obtaining the semiconductor member from the semiconductor object with the crack extending over the virtual plane as the boundary, it is possible to obtain a suitable semiconductor member.
  • a semiconductor object is a semiconductor ingot, a plurality of modified regions are provided so as to be arranged in a direction facing a surface, and a peripheral region corresponds to each of the plurality of modified regions.
  • the plurality of peripheral regions may prevent the crack from propagating from the surrounding modified region to another modified region adjacent to the modified region. According to this, it becomes possible to obtain a plurality of semiconductor wafers from one semiconductor ingot. Since the peripheral region prevents the cracks from propagating from the reforming region to another reforming region, it is possible to prevent the gas from escaping from the reforming region to another reforming region. It is possible to effectively raise or maintain the pressure.
  • a semiconductor object is a semiconductor wafer, a plurality of modified regions are provided so as to be arranged in a direction in which a surface extends, and a peripheral region corresponds to each of a plurality of virtual planes.
  • the plurality of peripheral regions may prevent the crack from propagating from the surrounding modified region to another modified region adjacent to the modified region. According to this, it becomes possible to acquire a plurality of semiconductor devices from one semiconductor wafer. Since the peripheral region prevents the cracks from propagating from the reforming region to the other reforming region, it is possible to prevent the gas from escaping from the reforming region to the other reforming region. It is possible to effectively raise or maintain the pressure.
  • FIG. 1 is a configuration diagram of a laser processing apparatus according to an embodiment.
  • FIG. 2 is a side view of a GaN ingot which is an object of the laser processing method and the semiconductor member manufacturing method of the first embodiment.
  • FIG. 3 is a plan view of the GaN ingot shown in FIG.
  • FIG. 4 is a cross-sectional view of the GaN ingot in the heating process of the laser processing method and the semiconductor member manufacturing method of the first embodiment.
  • FIG. 5 is a cross-sectional view of the GaN ingot in the heating process of the laser processing method and the semiconductor member manufacturing method of the first embodiment.
  • FIG. 6 is a cross-sectional view of the GaN ingot in the heating process of the laser processing method and the semiconductor member manufacturing method of the first embodiment.
  • FIG. 7 is a cross-sectional view of the GaN ingot in the heating process of the laser processing method and the semiconductor member manufacturing method of the first embodiment.
  • FIG. 8 is a side view of the GaN ingot after the heating step of the laser processing method and the semiconductor member manufacturing method of the first embodiment.
  • FIG. 9A is a photograph showing a first example of a GaN ingot in the heating step of the laser processing method and the semiconductor member manufacturing method of the first embodiment.
  • FIG. 9B is a photograph showing a second example of the GaN ingot in the heating step of the laser processing method and the semiconductor member manufacturing method of the first embodiment.
  • FIG. 9C is a photograph showing a third example of the GaN ingot in the heating step of the laser processing method and the semiconductor member manufacturing method of the first embodiment.
  • FIG. 9A is a photograph showing a first example of a GaN ingot in the heating step of the laser processing method and the semiconductor member manufacturing method of the first embodiment.
  • FIG. 9B is a photograph showing a second example
  • FIG. 9D is a photograph showing a fourth example of the GaN ingot in the heating step of the laser processing method and the semiconductor member manufacturing method of the first embodiment.
  • FIG. 10 is a side view of the GaN ingot in the peripheral region removing step of the laser processing method and the semiconductor member manufacturing method of the first embodiment.
  • FIG. 11 is a side view of the GaN ingot in the stimulation applying step of the laser processing method and the semiconductor member manufacturing method of the first embodiment.
  • FIG. 12A is a side view of the GaN ingot after the stimulation applying step in the laser processing method and the semiconductor member manufacturing method of the first embodiment.
  • FIG. 12B is a side view of the GaN wafer obtained by the laser processing method and the semiconductor member manufacturing method of the first embodiment.
  • FIG. 13 is a cross-sectional view of a GaN ingot in the heating process of the modified laser processing method and semiconductor member manufacturing method.
  • FIG. 14 is a side view of the GaN ingot in the peripheral region removing step of the modified laser processing method and semiconductor member manufacturing method.
  • FIG. 15 is a vertical cross-sectional view of a part of a GaN ingot in one step of the laser processing method and the semiconductor member manufacturing method of the modified example.
  • FIG. 16 is a cross-sectional view of a part of a GaN ingot in one step of the laser processing method and the semiconductor member manufacturing method of the modified example.
  • FIG. 17 is a vertical cross-sectional view of a part of the GaN ingot in one step of the laser processing method and the semiconductor member manufacturing method of the modified example.
  • FIG. 18 is a cross-sectional view of a part of a GaN ingot in one step of the laser processing method and the semiconductor member manufacturing method of the modified example.
  • FIG. 19 is a vertical cross-sectional view of a portion of a GaN ingot in one step of the laser processing method and semiconductor member manufacturing method of the modification.
  • FIG. 20 is a cross-sectional view of a part of a GaN ingot in one step of the laser processing method and the semiconductor member manufacturing method of the modified example.
  • FIG. 21 is a vertical cross-sectional view of a part of a GaN ingot in one step of the laser processing method and the semiconductor member manufacturing method of the modified example.
  • FIG. 22 is a cross-sectional view of a part of a GaN ingot in one step of the laser processing method and the semiconductor member manufacturing method of the modified example.
  • FIG. 23 is an image of the separated surface of the GaN wafer formed by the laser processing method and the semiconductor member manufacturing method of an example.
  • FIG. 24A is a height profile of the peeled surface shown in FIG.
  • FIG. 24B is a height profile of the peeled surface shown in FIG.
  • FIG. 25 is an image of the separated surface of the GaN wafer formed by the laser processing method and the semiconductor member manufacturing method of another example.
  • FIG. 26A is a height profile of the peeled surface shown in FIG.
  • FIG. 26B is a height profile of the peeled surface shown in FIG. FIG.
  • FIG. 27 is a schematic diagram for explaining the principle of forming a peeled surface by the laser processing method and the semiconductor member manufacturing method as an example.
  • FIG. 28 is a schematic diagram for explaining a principle of forming a peeled surface by a laser processing method and a semiconductor member manufacturing method of another example.
  • FIG. 29A is an image of a crack formed during the laser processing method and the semiconductor member manufacturing method of an example.
  • FIG. 29( b) is an enlarged image within the rectangular frame in FIG. 29( a ).
  • FIG. 30A is an image of a crack formed during the laser processing method and the semiconductor member manufacturing method of another example.
  • FIG. 30(b) is an enlarged image within the rectangular frame in FIG. 30(a).
  • FIG. 31 is an image of modified spots and cracks formed by the laser processing method and the semiconductor member manufacturing method of the comparative example.
  • FIG. 32A is an image in plan view of modified spots and cracks formed by the laser processing method and the semiconductor member manufacturing method of the first embodiment.
  • FIG. 32B is a side view image of modified spots and cracks formed by the laser processing method and the semiconductor member manufacturing method of the first embodiment.
  • FIG. 33A is an image in plan view of modified spots and cracks formed by the laser processing method and the semiconductor member manufacturing method of the second embodiment.
  • FIG. 33B is a side view image of modified spots and cracks formed by the laser processing method and the semiconductor member manufacturing method of the second embodiment.
  • FIG. 33C is an image in plan view of modified spots and cracks formed by the laser processing method and the semiconductor member manufacturing method of the third embodiment.
  • FIG. 33D is a side view image of modified spots and cracks formed by the laser processing method and the semiconductor member manufacturing method of the third embodiment.
  • FIG. 34 is a plan view of a GaN wafer which is an object of the laser processing method and the semiconductor member manufacturing method of the second embodiment.
  • FIG. 35 is a side view of a part of the GaN wafer in one step of the laser processing method and the semiconductor member manufacturing method of the second embodiment.
  • FIG. 36 is a side view of a part of the GaN wafer in one step of the laser processing method and the semiconductor member manufacturing method of the second embodiment.
  • FIG. 37 is a side view of the semiconductor device in one step of the laser processing method and the semiconductor member manufacturing method of the second embodiment.
  • the laser processing apparatus 1 includes a stage 2, a light source 3, a spatial light modulator 4, a condenser lens 5, and a control unit 6.
  • the laser processing apparatus 1 is an apparatus that forms a modified region 12 on the object 11 by irradiating the object 11 with a laser beam L.
  • the first horizontal direction will be referred to as the X direction
  • the second horizontal direction perpendicular to the first horizontal direction will be referred to as the Y direction.
  • the vertical direction is called the Z direction.
  • the stage 2 supports the target object 11 by, for example, adsorbing a film attached to the target object 11.
  • the stage 2 is movable along each of the X direction and the Y direction. Further, the stage 2 can rotate about an axis parallel to the Z direction as a center line.
  • the light source 3 outputs a laser beam L that is transparent to the object 11 by using, for example, a pulse oscillation method.
  • the spatial light modulator 4 modulates the laser light L output from the light source 3.
  • the spatial light modulator 4 is, for example, a reflective liquid crystal (LCOS: Liquid Crystal on Silicon) spatial light modulator (SLM: Spatial Light Modulator).
  • the condenser lens 5 condenses the laser light L modulated by the spatial light modulator 4.
  • the spatial light modulator 4 and the condenser lens 5 are movable as a laser irradiation unit along the Z direction.
  • the modified region 12 is a region in which density, refractive index, mechanical strength, and other physical properties are different from those of the surrounding unmodified region.
  • the modified region 12 includes, for example, a melt-processed region, a crack region, a dielectric breakdown region, and a refractive index change region.
  • a plurality of modified spots 13 are moved along the X direction by 1. It is formed so as to line up in a row.
  • One modified spot 13 is formed by irradiation with one pulse of laser light L.
  • the one-row reforming region 12 is a set of a plurality of reforming spots 13 arranged in one row.
  • the adjacent modified spots 13 may be connected to each other or may be separated from each other depending on the relative moving speed of the condensing point C with respect to the object 11 and the repetition frequency of the laser light L.
  • the control unit 6 controls the stage 2, the light source 3, the spatial light modulator 4, and the condenser lens 5.
  • the control unit 6 is configured as a computer device including a processor, a memory, a storage, a communication device, and the like.
  • the software (program) read into the memory or the like is executed by the processor, and the reading and writing of data in the memory and the storage and the communication by the communication device are controlled by the processor. Thereby, the control unit 6 realizes various functions.
  • the object 11 of the laser processing method and the semiconductor member manufacturing method of the first embodiment is, as shown in FIGS. 2 and 3, a GaN ingot (semiconductor ingot, formed of gallium nitride (GaN) in a rectangular plate shape, for example.
  • Semiconductor object) 20 As an example, the GaN ingot 20 has a width of 30 mm and a width of 30 mm, and the GaN ingot 20 has a thickness of 2 mm.
  • the laser processing method and the semiconductor member manufacturing method of the first embodiment are performed to cut out a plurality of GaN wafers (semiconductor wafers, semiconductor members) 30 from the GaN ingot 20.
  • the width of the GaN wafer 30 is 10 mm in length and 10 mm in width, and the thickness of the GaN wafer 30 is 100 ⁇ m.
  • the shapes of the GaN ingot 20 and the GaN wafer 30 are not particularly limited, and may be circular plate shapes, for example.
  • each of the plurality of virtual surfaces 15 is a surface facing the surface 20a of the GaN ingot 20 inside the GaN ingot 20, and is set to be aligned in a direction facing the surface 20a.
  • each of the plurality of virtual surfaces 15 is a surface parallel to the surface 20a and has, for example, a rectangular shape.
  • Each of the plurality of virtual surfaces 15 is set so as to overlap each other when viewed from the front surface 20a side.
  • a plurality of peripheral regions 16 are set in the GaN ingot 20 so as to surround each of the plurality of virtual surfaces 15.
  • each of the plurality of virtual surfaces 15 does not reach the side surface 20b of the GaN ingot 20.
  • the distance between the adjacent virtual surfaces 15 is 100 ⁇ m
  • the width of the peripheral region 16 (in the present embodiment, the distance between the outer edge of the virtual surface 15 and the side surface 20b) is 30 ⁇ m or more.
  • a region surrounded by the peripheral region 16 in the GaN ingot 20 is a processing target region R in which the modified region 12 is formed.
  • the processing target region R includes the virtual surface 15. Details of the peripheral region 16 will be described later.
  • the formation of the modified region 12 is sequentially performed for each virtual surface 15 from the side opposite to the surface 20a by irradiation with the laser light L having a wavelength of 532 nm, for example.
  • a plurality of modified regions 12 are provided corresponding to each of the plurality of virtual surfaces 15. Since the formation of the modified region 12 is the same for each of the plurality of virtual surfaces 15, the formation of the modified region 12 along the virtual surface 15 closest to the surface 20a will be described in detail below.
  • the modified spots 13a, 13b, 13c, and 13d described later may be collectively referred to as the modified spot 13, and the cracks 14a, 14b, 14c, and 14d described later may be collectively referred to as the crack 14.
  • the condensing point C of the laser light L is moved along the virtual plane 15 in the X direction and Move in Y direction.
  • the modified region 12 is formed along the virtual surface 15 in the processing target region R surrounded by the peripheral region 16 of the GaN ingot 20.
  • a plurality of modified spots 13a arranged in the X direction and the Y direction, a plurality of cracks 14b respectively extending from the plurality of modified spots 13b, and the GaN ingot 20 being decomposed by the irradiation of the laser light L (chemical change).
  • the plurality of modified spots 13a are provided in a matrix on the virtual surface 15.
  • the plurality of cracks 14b include microcracks.
  • the plurality of cracks 14b may be connected to each other or may not be connected to each other.
  • the nitrogen gas G is generated in the cracks 14.
  • the nitrogen gas G is generated so as to be scattered in one or a plurality of places in the reforming region 12 (processing target region R).
  • the modified spot 13a is shown by a black square, and the range in which the crack 14a extends is shown by a broken line (also in FIGS. 5 and 6).
  • the modified spot 13a is not formed in the modified region 12 and the outer surface of the GaN ingot 20 (the surface 20a, another surface opposite to the surface 20a) from the modified region 12 is formed.
  • the GaN ingot 20 is provided with a peripheral region 16 that prevents the crack 14b from propagating to the surface 20c and the side face 20b) so as to surround the modified region 12.
  • the peripheral region 16 has a frame shape surrounding the modified region 12 when viewed from the Z direction (direction facing the surface 20a).
  • a plurality of peripheral areas 16 are provided corresponding to each of the virtual surfaces 15. The peripheral region 16 further prevents the crack 14b from propagating from the surrounding modified region 12 to another modified region 12 adjacent to the modified region 12.
  • Blocking the growth of the crack 14b is not limited to completely blocking the growth of the crack 14b, and preventing the crack 14b from reaching the outer surface of the GaN ingot 20 as much as possible, and preventing the crack 14b from growing. And/or hindering the development of the crack 14b.
  • on-off irradiation for switching the irradiation of the laser light L to the processing target region R and the peripheral region 16 between on and off is performed, and thus the peripheral region 16 is performed. May be provided. That is, the laser beam L is turned off when the converging point C is located in the peripheral region 16, and the irradiation of the laser beam L is turned on when the converging point C is located inside the peripheral region 16 (region R to be processed). Good.
  • the crack 14b does not propagate under the processing conditions of the laser light L from the modified region 12 to the outer surface of the GaN ingot 20 and/or to the other modified region 12.
  • the peripheral region 16 may be provided under the conditions.
  • the processing conditions for providing the peripheral region 16 can be set based on a known technique.
  • the processing conditions for providing the peripheral region 16 include the laser beam L energy and pulse pitch setting conditions.
  • the energy of the laser light L is set to be smaller than the predetermined energy and the pulse pitch is set to be longer than the predetermined length.
  • the peripheral region 16 may be provided by covering the region other than the region R to be processed of the GaN ingot 20 with a mask that blocks laser incidence.
  • the bevel portion (also referred to as an inclined portion or a tapered portion) existing at the outer edge of the surface 20a of the GaN ingot 20 is used to generate the laser light L.
  • the peripheral region 16 may be provided by suppressing light collection.
  • the heating device includes a heating plate, a device for performing additional laser processing, a heater, a heating furnace, an LD (Laser Diode) heater, a device for heating with a light source such as a laser device, a device for heating with ultrasonic waves, and a device with shock waves for heating. It may include at least one of a device for performing heating and a device for performing heating by electromagnetic waves.
  • the reformed region 12 contains the nitrogen gas G. Therefore, in the heating step, by heating the GaN ingot 20, the nitrogen gas G is expanded and the pressure (internal pressure) of the nitrogen gas G is increased as shown in FIGS. As a result, the nitrogen gas G is connected to one and spreads over the entire virtual surface 15 (processing target region R). Using the pressure of the nitrogen gas G, the plurality of cracks 14 extending from the plurality of reforming spots 13 are connected to each other on the virtual surface 15. A plurality of cracks 14 are propagated along the virtual surface 15 to form a large crack 17 (hereinafter, simply referred to as “crack 17”) across the virtual surface 15.
  • crack 17 a large crack 17
  • cracks 17 are formed on each of the virtual surfaces 15 in the heating process.
  • a range in which the plurality of modified spots 13, the plurality of cracks 14, and the crack 17 are formed is indicated by a broken line. Molten precipitates may enter the cracks 17.
  • the cracks 14 and 17 are also referred to below as voids.
  • the peripheral region 16 prevents the plurality of cracks 14 (cracks 17) from propagating, and thus the generated nitrogen gas G can be suppressed from escaping to the outside of the virtual surface 15.
  • a peripheral region 16 can have a width of 30 ⁇ m or more.
  • the cracks 17 may be formed by connecting the plurality of cracks 14 to each other by applying some force to the GaN ingot 20 by a method other than heating. Further, by forming the plurality of modified spots 13 along the virtual surface 15, the plurality of cracks 14 may be connected to each other to form the crack 17.
  • FIGS. 9A to 9D are photographic diagrams showing the processing target region R when the GaN ingot 20 having the modified region 12 formed thereon is heated.
  • the heating temperature is 40° C.
  • the heating temperature is 85° C.
  • the heating temperature is 165° C.
  • the heating temperature is 350° C.
  • FIGS. 9A to 9C as the temperature of the GaN ingot 20 rises, the nitrogen gas G expands along the virtual plane 15 and the crack 14 grows. Then, as shown in FIG. 9D, it can be confirmed that the expansion of the nitrogen gas G is suppressed and sealed in the peripheral region 16 and the expanded crack 17 is formed over almost the entire virtual surface 15. ..
  • the following GaN ingot 20 is obtained as a semiconductor ingot (semiconductor object).
  • the modified region 12 formed along the virtual surface 15 facing the surface 20 a and the peripheral region 16 provided so as to surround the modified region 12.
  • the reforming region 12 includes a plurality of reforming spots 13, a plurality of cracks 14 extending from the plurality of reforming spots 13, and a nitrogen gas G, respectively.
  • a plurality of modified regions 12 are provided so as to be aligned in the Z direction.
  • the peripheral region 16 is a region where the modified spot 13 is not formed, and prevents the crack 14 from propagating from the surrounding modified region 12 to the outer surface of the GaN ingot 20.
  • a plurality of peripheral regions 16 are provided corresponding to each of the plurality of modified regions 12. The peripheral region 16 prevents the crack 14 from propagating from the surrounding modified region 12 to another modified region 12 adjacent to the modified region 12.
  • a peripheral region removing step of removing a plurality of peripheral regions 16 of the GaN ingot 20 is performed.
  • the laser processing apparatus 1 causes the laser light to travel along the planned cutting plane M set at the boundary between the peripheral area 16 and the virtual surface 15 (processing target area R).
  • L2 is focused inside the GaN ingot 20.
  • a modified region and a crack are formed inside the GaN ingot 20 along the planned cutting surface M.
  • the formation of such modified regions and cracks can be realized by general laser processing for cutting.
  • the GaN ingot 20 is cut along the modified region and the crack thus formed, and the plurality of peripheral regions 16 are cut off from the GaN ingot 20.
  • the modified region 12 (deposition surface of deposited gallium) is exposed.
  • the portion corresponding to the peripheral area 16 may be mechanically removed using a blade (crystal cutter) or the like. In the peripheral area removing step, the portion corresponding to the peripheral area 16 may be removed by blade dicing. In the peripheral area removing step, the portion corresponding to the peripheral area 16 may be removed using a wire saw such as a diamond wire. In the peripheral area removing step, the portion corresponding to the peripheral area 16 may be ground (polished) with an abrasive such as a grindstone.
  • a stimulus applying step of externally applying a stimulus to the plurality of modified regions 12 formed on the GaN ingot 20 is performed.
  • the laser processing apparatus 1 focuses the laser light L3 inside the modified region 12 and applies the stimulus to the modified region 12.
  • the internal pressure releasing effect of the nitrogen gas G contained in the reformed region 12 is also used, and as shown in FIG. 12A, a part of the GaN ingot 20 is peeled off along the virtual surface 15.
  • the laser light L3 is simultaneously or sequentially focused inside the plurality of modified regions 12, and each part of the GaN ingot 20 is stripped simultaneously or sequentially along the virtual surface 15.
  • a stimulus may be used to mechanically apply stimulus to the modified region 12.
  • stimulus may be applied to the modified region 12 by blade dicing.
  • a stimulus may be applied to the modified region 12 using a wire saw such as a diamond wire.
  • the stimulus may be applied from one outer surface (one direction) of the GaN ingot 20 or may be applied from a plurality of outer surfaces (multi-directions).
  • stimulation may be applied to the modified region 12 in a non-contact manner by ultrasonic vibration or the like.
  • stimulus may be applied to at least the precipitate and the crack 17 in the modified region 12.
  • a wafer forming process is performed on each part of the separated GaN ingot 20 by removing the modified region 12 to form a wafer.
  • the modified region 12 remaining on each part of the separated GaN ingot 20 is removed by etching or polishing.
  • the modified region 12 may be removed by other mechanical processing, laser processing, or the like.
  • the GaN ingot 20 is sliced starting from the plurality of modified regions 12. That is, the GaN ingot 20 is cut using the crack 17.
  • a plurality of GaN wafers 30 are obtained from the GaN ingot 20 with each of the plurality of cracks 17 as a boundary.
  • the laser processing step is the laser processing method of the first embodiment.
  • the steps up to the step of obtaining the plurality of GaN wafers 30 are the semiconductor member manufacturing method of the first embodiment.
  • the peripheral region removing step, the stimulating step, and the wafer forming step constitute the second step.
  • the peripheral region 16 can prevent the crack 14 from propagating from the modified region 12 to the outer surface of the GaN ingot 20. It is possible to prevent the nitrogen gas G contained in the reformed region 12 from escaping to the outside through the crack 14. Therefore, the pressure (internal pressure) of the nitrogen gas G can be effectively increased or maintained. As a result, it is possible to easily form the crack 17 across the virtual surface 15 using the internal pressure. By obtaining the GaN wafer 30 from the GaN ingot 20 with the crack 17 across the virtual plane 15 as the boundary, it is possible to obtain the suitable GaN wafer 30.
  • the amount of progress of the crack 14 along the virtual surface 15 is large, and the area of the virtual surface 15 can be increased.
  • Good cutting (slicing) along the virtual surface 15 can be realized. It is possible to obtain a peeled surface (cut surface) having small unevenness.
  • the unevenness of the peeling surface by general slicing is about 25 ⁇ m, while the unevenness of the peeling surface according to the first embodiment is as small as 5 ⁇ m.
  • the peripheral region 16 has a frame shape surrounding the modified region 12 when viewed from the Z direction. By forming such a peripheral region 16, it is possible to effectively prevent the crack 14 from propagating to the outer surface of the GaN ingot 20.
  • the GaN ingot 20 is used as the semiconductor object.
  • the GaN ingot 20 containing a nitride it is possible to decompose the GaN ingot 20 and generate the nitrogen gas G by making the laser light L enter the inside of the GaN ingot 20.
  • gallium nitride is being applied to optical devices or power devices, and in this respect also, it is effective to use the GaN ingot 20 as a semiconductor object.
  • a plurality of virtual surfaces 15 are set so as to be lined up in the Z direction.
  • a plurality of modified regions 12 and peripheral regions 16 are provided corresponding to each of the plurality of virtual surfaces 15.
  • the peripheral region 16 prevents the crack 14 from propagating from the surrounding modified region 12 to another modified region 12 adjacent to the modified region 12. According to this, a plurality of GaN wafers 30 can be obtained from one GaN ingot 20. Further, since the peripheral region 16 prevents the crack 14 from propagating from the reforming region 12 to another reforming region 12, the nitrogen gas G escapes from the reforming region 12 to the other reforming region 12. This can be suppressed, and the pressure of the nitrogen gas G can be effectively increased or maintained.
  • the GaN ingot 20 is heated and the nitrogen gas G is expanded to cause the crack 14 to propagate along the virtual surface 15. As a result, the crack 14 extending over the virtual surface 15 can be reliably formed.
  • a stimulus is externally applied to the modified region 12 to peel off a part of the GaN ingot 20 along the virtual surface 15. According to this, while releasing the pressure of the nitrogen gas G in the reforming region 12, a part of the GaN ingot 20 can be peeled off by also utilizing this released force.
  • the peripheral region 16 prevents the crack 14 from propagating from the reformed region 12 to the outer surface of the GaN ingot 20, and the nitrogen gas G contained in the reformed region 12 cracks 14. Escape to the outside through the is suppressed. Therefore, the pressure of the nitrogen gas G can be effectively increased or maintained. Using the internal pressure, the crack 14 can be accurately propagated along the virtual surface 15. By obtaining the GaN wafer 30 from the GaN ingot 20 with the crack 17 across the virtual plane 15 as the boundary, it is possible to obtain the suitable GaN wafer 30.
  • a plurality of modified regions 12 are provided so as to be lined up in the Z direction.
  • a plurality of peripheral regions 16 are provided corresponding to each of the plurality of modified regions 12, and prevent the crack 14 from propagating from the surrounding modified region 12 to another modified region 12 adjacent to the modified region 12. According to this, it becomes possible to acquire a plurality of GaN wafers 30 from one GaN ingot 20. It is possible to prevent the nitrogen gas G from escaping from the reforming region 12 to another reforming region 12, and it is possible to effectively increase or maintain the pressure of the nitrogen gas G.
  • the peripheral region 16 also blocks the outflow of the precipitate deposited by decomposition of the nitride and melted to the outside. Accordingly, the precipitate can be retained in the processing target region R, and the precipitate can be used as a starting point when heating in the subsequent heating step.
  • the above-described laser processing method and semiconductor member manufacturing method may further include a hole forming step of forming holes H1, H2, and H3 that allow the nitrogen gas G to escape to the outside in the peripheral region 16. ..
  • the hole forming step is performed before the heating step.
  • the holes H1, H2, H3 are holes for venting the gas contained in the reforming region 12.
  • the holes H1, H2, H3 communicate the inside and outside of the peripheral region 16.
  • the holes H1, H2, H3 are configured so that the pressure of the nitrogen gas G does not drop below a certain level.
  • the hole H1 is a first hole reaching the side surface 20b from the modified region 12 (processing target region R).
  • the hole H2 is a second hole that reaches the side surface 20b from the modified region 12 and has a larger diameter than the hole H1.
  • the hole H3 is a third hole reaching the corner of the GaN ingot 20 from the modified region 12.
  • the holes H1, H2, H3 may be formed by utilizing a crack extending from the modified region 12 when the modified region 12 is formed by the laser processing device 1 described above. Even in this case, the function of the peripheral region 16 can be ensured.
  • the method for forming the holes H1, H2, H3 is not particularly limited, and various known methods can be used.
  • the hole forming step and the holes H1, H2, and H3 resulting therefrom when the strain or warpage is applied to the GaN ingot 20 due to the increase (expansion) of the pressure of the nitrogen gas G, the nitrogen gas G is released to the outside to cause the strain.
  • the warp can be suppressed. It is possible to suppress the occurrence of cracks and dislocations due to the strain or warpage. It is possible to prevent a part of the GaN ingot 20 from peeling off spontaneously. For example, when a wax or the like is attached and peeled off, the adhesion can be enhanced.
  • the etchant can easily enter, and the etching rate can be increased.
  • At least one of the holes H1, H2, H3 may be formed.
  • the number and size of the holes H1, H2, H3 are not particularly limited, and can be set according to the amount of gallium deposited and the internal pressure of the nitrogen gas G.
  • the direction of processing for removing the plurality of peripheral areas 16 is not limited, and processing may be performed from the surface 20a side, the side surface 20b side, or the surface 20c side. It may be processed from.
  • a portion corresponding to the peripheral edge region 16 is polished by bringing an abrasive material PL such as a grindstone close to the side surface 20b along the extending direction of the modified region 12. May be.
  • the formation of the modified region 12 (the plurality of modified spots 13) along the virtual surface 15 is not particularly limited, and may be formed as follows.
  • the laser processing apparatus 1 causes the laser light L to enter the inside of the GaN ingot 20 from the front surface 20 a, so that the laser light L is incident along the virtual surface 15 (for example, in the virtual surface 15).
  • a plurality of modified spots (first modified spots) 13a are formed so as to be arranged two-dimensionally along the whole.
  • the laser processing apparatus 1 forms the plurality of modified spots 13a so that the plurality of cracks 14a extending from the plurality of modified spots 13a are not connected to each other.
  • the laser processing apparatus 1 forms the modified spots 13a in a plurality of rows by moving the condensing point C of the pulsed laser light L along the virtual surface 15.
  • the modified spot 13a is shown in white (without hatching), and the range in which the crack 14a extends is shown by a broken line (the same applies to FIGS. 17 to 22).
  • the pulsed laser light L is modulated by the spatial light modulator 4 so as to be condensed at a plurality of (for example, six) condensing points C arranged in the Y direction. Then, the plurality of condensing points C are relatively moved on the virtual surface 15 along the X direction.
  • the distance between the condensing points C adjacent to each other in the Y direction is 8 ⁇ m
  • the pulse pitch of the laser light L that is, the relative moving speed of the plurality of condensing points C is determined by the repetition frequency of the laser light L).
  • the divided value is 10 ⁇ m.
  • the pulse energy of the laser light L per one condensing point C (hereinafter, simply referred to as “pulse energy of the laser light L”) is 0.33 ⁇ J.
  • the center-to-center distance between adjacent modified spots 13a in the Y direction is 8 ⁇ m
  • the center-to-center distance between adjacent modified spots 13a in the X direction is 10 ⁇ m.
  • the cracks 14a extending from the modified spots 13a are not connected to each other.
  • the laser processing apparatus 1 causes the laser light L to enter the inside of the GaN ingot 20 from the surface 20a as shown in FIGS.
  • a plurality of modified spots (second modified spots) 13b are formed so as to be arranged two-dimensionally along the entire area.
  • the laser processing apparatus 1 forms the plurality of modified spots 13b so as not to overlap the plurality of modified spots 13a and the plurality of cracks 14a.
  • the laser processing apparatus 1 moves the condensing point C of the pulsed laser light L along the virtual plane 15 between the rows of the reforming spots 13a of the plurality of rows to thereby form the reforming spots 13b of the plurality of rows. To form.
  • the cracks 14b extending from the modified spots 13b may be connected to the cracks 14a. 17 and 18, the modified spot 13b is indicated by dot hatching, and the range in which the crack 14b extends is indicated by broken lines (the same applies to FIGS. 19 to 22).
  • the pulsed laser light L is modulated by the spatial light modulator 4 so as to be condensed at a plurality of (for example, six) condensing points C arranged in the Y direction. Then, the plurality of condensing points C are relatively moved on the virtual surface 15 along the X direction at the centers between the rows of the reformed spots 13a.
  • the distance between the condensing points C adjacent to each other in the Y direction is 8 ⁇ m
  • the pulse pitch of the laser light L is 10 ⁇ m.
  • the pulse energy of the laser light L is 0.33 ⁇ J.
  • the center-to-center distance between adjacent modified spots 13b in the Y direction is 8 ⁇ m
  • the center-to-center distance between adjacent modified spots 13b in the X direction is 10 ⁇ m.
  • the laser processing device 1 causes the laser light L to enter the inside of the GaN ingot 20 from the surface 20 a, so that the laser light L is guided along the virtual surface 15 (for example, the virtual surface 15).
  • a plurality of modified spots (third modified spots) 13c are formed so as to be arranged two-dimensionally along the entire area.
  • the laser processing apparatus 1 causes the laser light L to enter the inside of the GaN ingot 20 from the surface 20 a, so that the laser light L is guided along the virtual surface 15 (for example, the virtual surface 15
  • a plurality of modified spots (third modified spots) 13d are formed so as to be arranged two-dimensionally along the whole.
  • the laser processing apparatus 1 forms the plurality of modified spots 13c and 13d so as not to overlap the plurality of modified spots 13a and 13b. Further, the laser processing apparatus 1 moves the condensing point C of the pulsed laser light L along the virtual plane 15 between the rows of the reforming spots 13a and 13b of the plurality of rows, thereby reforming the plurality of rows.
  • the spots 13c and 13d are formed.
  • the cracks 14c and 14d extending from the modified spots 13c and 13d may be connected to the cracks 14a and 14b.
  • the modified spot 13c is shown by solid line hatching, and the range in which the crack 14c extends is shown by broken lines (also in FIGS. 21 and 22).
  • the modified spot 13d is shown by solid line hatching (solid line hatching that is the reverse of the solid line hatching of the modified spot 13c), and the range in which the crack 14d extends is shown by broken lines. There is.
  • the pulsed laser light L is modulated by the spatial light modulator 4 so as to be condensed at a plurality of (for example, six) condensing points C arranged in the Y direction. Then, the plurality of converging points C are relatively moved on the virtual surface 15 along the X direction at the center between the rows of the reformed spots 13a and 13b of the plurality of rows.
  • the distance between the condensing points C adjacent to each other in the Y direction is 8 ⁇ m
  • the pulse pitch of the laser light L is 5 ⁇ m.
  • the pulse energy of the laser light L is 0.33 ⁇ J.
  • the center-to-center distance between adjacent modified spots 13c in the Y direction is 8 ⁇ m
  • the center-to-center distance between adjacent modified spots 13c in the X direction is 5 ⁇ m.
  • the center-to-center distance between the modified spots 13d adjacent to each other in the Y direction is 8 ⁇ m
  • the center-to-center distance between the modified spots 13d adjacent to each other in the X-direction is 5 ⁇ m.
  • FIG. 23 is an image of a peeled surface of a GaN wafer formed by the laser processing method and the semiconductor member manufacturing method of an example
  • FIGS. 24A and 24B show the height of the peeled surface shown in FIG. It is a profile.
  • laser light L having a wavelength of 532 nm is made incident on the inside of the GaN ingot 20 from the surface 20a of the GaN ingot 20, and one condensing point C is relatively moved on the virtual plane 15 along the X direction. By moving, a plurality of modified spots 13 were formed along the virtual surface 15.
  • the distance between adjacent condensing points C in the Y direction was 10 ⁇ m
  • the pulse pitch of the laser light L was 1 ⁇ m
  • the pulse energy of the laser light L was 1 ⁇ J.
  • irregularities of about 25 ⁇ m appeared on the separation surface (surface formed by the crack 17) of the GaN wafer 30.
  • FIG. 25 is an image of a peeled surface of a GaN wafer formed by another example of the laser processing method and the semiconductor member manufacturing method
  • FIGS. 26A and 26B are images of the peeled surface shown in FIG. It is a height profile.
  • laser light L having a wavelength of 532 nm is made to enter the inside of the GaN ingot 20 from the surface 20a of the GaN ingot 20, and along the virtual plane 15 as in the modified laser processing method and semiconductor member manufacturing method.
  • a plurality of modified spots 13 were formed.
  • the distance between the condensing points C adjacent to each other in the Y direction was 6 ⁇ m
  • the pulse pitch of the laser light L was 10 ⁇ m
  • the pulse energy of the laser light L was 0.33 ⁇ J.
  • the distance between the condensing points C adjacent to each other in the Y direction was 6 ⁇ m
  • the pulse pitch of the laser light L was 10 ⁇ m
  • the pulse energy of the laser light L was 0.33 ⁇ J.
  • the distance between the condensing points C adjacent to each other in the Y direction was 6 ⁇ m
  • the pulse pitch of the laser light L was 5 ⁇ m
  • the pulse energy of the laser light L was 0.33 ⁇ J.
  • the distance between the condensing points C adjacent to each other in the Y direction was 6 ⁇ m
  • the pulse pitch of the laser light L was 5 ⁇ m
  • the pulse energy of the laser light L was 0.33 ⁇ J.
  • unevenness of about 5 ⁇ m appeared on the separated surface of the GaN wafer 30.
  • the irregularities appearing on the separated surface of the GaN wafer 30 are small, that is, the cracks 17 are formed along the virtual surface 15. It was found that it was formed accurately. It should be noted that if the irregularities appearing on the peeled surface of the GaN wafer 30 become small, the amount of grinding for flattening the peeled surface will be small. Therefore, it is advantageous in terms of material utilization efficiency and production efficiency that the irregularities appearing on the separated surface of the GaN wafer 30 become small.
  • a plurality of modified spots 13a are formed along the imaginary plane 15, and the modified spots 13b are virtual so that the modified spots 13b overlap the cracks 14a extending from the modified spots 13a on one side.
  • a plurality of modified spots 13b are formed along the surface 15.
  • the laser light L is easily absorbed by the gallium deposited in the plurality of cracks 14a, even if the condensing point C is located on the virtual surface 15, the laser is not applied to the modified spot 13a.
  • the modified spot 13b is easily formed on the incident side of the light L.
  • a plurality of modified spots 13c are formed along the virtual surface 15 so that the modified spots 13c overlap the cracks 14b extending from the modified spots 13b on one side.
  • the laser light L is easily absorbed by the gallium deposited in the plurality of cracks 14b, even if the condensing point C is located on the virtual surface 15, the laser is not applied to the modified spot 13b.
  • the modified spot 13c is easily formed on the incident side of the light L.
  • the plurality of modified spots 13b are formed on the incident side of the laser light L with respect to the plurality of modified spots 13a, and further, the plurality of modified spots 13c are formed into the plurality of modified spots 13b. On the other hand, it tends to be formed on the incident side of the laser light L.
  • a plurality of modified spots 13a are formed along the virtual surface 15 so that the modified spots 13b do not overlap the cracks 14a extending from the modified spots 13a on both sides thereof.
  • a plurality of modified spots 13b are formed along the virtual surface 15.
  • the laser light L is easily absorbed by the gallium deposited in the plurality of cracks 14a, the modified spot 13b does not overlap the crack 14a, so the modified spot 13b is similar to the modified spot 13a.
  • a plurality of modified spots 13c are formed along the virtual surface 15 so that the modified spots 13c overlap the cracks 14a and 14b extending from the modified spots 13a and 13b on both sides thereof.
  • a plurality of modified spots 13d are formed along the virtual surface 15 so that the modified spots 13d overlap the cracks 14a and 14b extending from the modified spots 13a and 13b on both sides thereof.
  • the modified spots 13c and 13d are easily formed on the incident side of the laser light L with respect to 13b. As described above, in this example, the modified spots 13c and 13d are easily formed on the incident side of the laser light L with respect to the modified spots 13a and 13b.
  • the plurality of modified spots 13a and the plurality of modified spots 13a are formed so as not to overlap with the plurality of cracks 14a extending from the plurality of modified spots 13a. It can be seen that the formation of 13b is extremely important for reducing the unevenness appearing on the separated surface of the GaN wafer 30.
  • FIG. 29A and 29B are images of cracks formed during the example of the laser processing method and the semiconductor member manufacturing method
  • FIG. 29B is a rectangle in FIG. 29A. It is an enlarged image in the frame.
  • laser light L having a wavelength of 532 nm is made incident on the inside of the GaN ingot 20 from the surface 20a of the GaN ingot 20, and the six condensing points C arranged in the Y direction are arranged on the virtual surface 15 along the X direction. Were relatively moved to form a plurality of modified spots 13 along the virtual surface 15.
  • the distance between the condensing points C adjacent to each other in the Y direction was 6 ⁇ m
  • the pulse pitch of the laser light L was 1 ⁇ m
  • the pulse energy of the laser light L was 1.33 ⁇ J.
  • the laser processing was stopped in the middle of the virtual surface 15. In this case, as shown in (a) and (b) of FIG. 29, the crack that propagated from the processed region to the unprocessed region largely deviated from the virtual surface 15 in the unprocessed region.
  • FIG. 30A and 30B are images of cracks formed during the laser processing method and the semiconductor member manufacturing method of another example, and FIG. 30B is the image of FIG. It is an enlarged image in the rectangular frame in.
  • laser light L having a wavelength of 532 nm is made to enter the inside of the GaN ingot 20 from the surface 20a of the GaN ingot 20, and the six condensing points C arranged in the Y direction are arranged on the virtual surface 15 along the X direction. Were relatively moved to form a plurality of modified spots 13 along the virtual surface 15.
  • the processing area 1 and the processing area 2 are set such that the distance between the condensing points C adjacent to each other in the Y direction is 6 ⁇ m, the pulse pitch of the laser light L is 10 ⁇ m, and the pulse energy of the laser light L is 0.33 ⁇ J.
  • a plurality of rows of modified spots 13 were formed on the surface. Then, the distance between the condensing points C adjacent to each other in the Y direction is 6 ⁇ m, the pulse pitch of the laser light L is 10 ⁇ m, and the pulse energy of the laser light L is 0.33 ⁇ J.
  • a plurality of rows of modified spots 13 were formed such that each row was positioned in the center between the plurality of rows of modified spots 13.
  • the distance between the condensing points C adjacent to each other in the Y direction is 6 ⁇ m
  • the pulse pitch of the laser light L is 5 ⁇ m
  • the pulse energy of the laser light L is 0.33 ⁇ J.
  • a plurality of rows of reforming spots 13 were formed such that each row was positioned at the center between the rows of reforming spots 13. In this case, as shown in (a) and (b) of FIG. 30, the crack that propagated from the processing region 1 to the processing region 2 did not largely deviate from the virtual surface 15 in the processing region 2.
  • FIG. 31 is an image (a side view image) of modified spots and cracks formed by the laser processing method and the semiconductor member manufacturing method of the comparative example.
  • a laser beam L having a wavelength of 532 nm is made incident on the inside of the GaN ingot 20 from the surface 20a of the GaN ingot 20, and one condensing point C is relatively moved on the virtual plane 15 along the X direction.
  • the plurality of modified spots 13 were formed along the imaginary plane 15 by moving the modified spots 13 to.
  • the distance between the condensing points C adjacent to each other in the Y direction is 2 ⁇ m
  • the pulse pitch of the laser light L is 5 ⁇ m
  • the pulse energy of the laser light L is 0.3 ⁇ J.
  • Quality spot 13 was formed.
  • the extension amount of the crack 14 extending from the modified spot 13 to the laser light L incident side and the opposite side was about 100 ⁇ m.
  • FIG. 32A and 32B are images of modified spots and cracks formed by the laser processing method and the semiconductor member manufacturing method of the first embodiment.
  • FIG. 32A is an image in plan view
  • FIG. I is an image in side view.
  • laser light L having a wavelength of 532 nm is made incident on the inside of the GaN ingot 20 from the surface 20a of the GaN ingot 20, and the six condensing points C arranged in the Y direction are virtual along the X direction.
  • a plurality of modified spots 13 were formed along the virtual surface 15.
  • the distance between the condensing points C adjacent to each other in the Y direction is 8 ⁇ m
  • the pulse pitch of the laser light L is 10 ⁇ m
  • the pulse energy of the laser light L is 0.3 ⁇ J.
  • the modified spot 13a of No. 1 was formed.
  • the distance between the converging points C adjacent in the Y direction is 8 ⁇ m
  • the pulse pitch of the laser light L is 10 ⁇ m.
  • a plurality of modified spots 13b were formed along the virtual surface 15 by setting the pulse energy of the laser light L to 0.3 ⁇ J.
  • the distance between the converging points C adjacent to each other in the Y direction is 8 ⁇ m, and the pulse pitch of the laser light L is changed.
  • a plurality of modified spots 13 were formed along the virtual surface 15 with the pulse energy of the laser beam L being 5 ⁇ m and 0.3 ⁇ J.
  • the distance between the converging points C adjacent in the Y direction is 8 ⁇ m, and the pulse pitch of the laser light L is 5 ⁇ m.
  • a plurality of modified spots 13 were formed along the virtual surface 15 with the pulse energy of the laser light L set to 0.3 ⁇ J.
  • the modified spot 13a formed for the first time and the modified spot formed for the third time overlap each other
  • the modified spot 13b formed for the second time and the modified spot formed for the fourth time overlap each other.
  • the extension amount of the crack 14 extending from the modified spot 13 to the laser light L incident side and the opposite side was about 70 ⁇ m.
  • FIG. 33A and 33B are images of modified spots and cracks formed by the laser processing method and the semiconductor member manufacturing method of the second embodiment, and FIG. 33A is a plan view.
  • the image, (b) of FIG. 33 is an image in a side view.
  • a laser beam L having a wavelength of 532 nm is made incident on the inside of the GaN ingot 20 from the surface 20a of the GaN ingot 20, and the virtual surface 15 is formed in the same manner as in the laser processing method and the semiconductor member manufacturing method of the modified example.
  • a plurality of modified spots 13 were formed along the line.
  • the distance between the condensing points C adjacent to each other in the Y direction was 8 ⁇ m
  • the pulse pitch of the laser light L was 10 ⁇ m
  • the pulse energy of the laser light L was 0.3 ⁇ J.
  • the distance between the condensing points C adjacent to each other in the Y direction was 8 ⁇ m
  • the pulse pitch of the laser light L was 10 ⁇ m
  • the pulse energy of the laser light L was 1.8 ⁇ J.
  • the distance between the condensing points C adjacent to each other in the Y direction was 8 ⁇ m
  • the pulse pitch of the laser light L was 5 ⁇ m
  • the pulse energy of the laser light L was 0.3 ⁇ J.
  • the distance between the condensing points C adjacent to each other in the Y direction was 8 ⁇ m
  • the pulse pitch of the laser light L was 5 ⁇ m
  • the pulse energy of the laser light L was 0.3 ⁇ J.
  • the extension amount of the crack 14 extending from the modified spot 13 to the incident side of the laser light L and the opposite side thereof was about 50 ⁇ m.
  • FIG. 33C and 33D are images of modified spots and cracks formed by the laser processing method and the semiconductor member manufacturing method of the third embodiment, and FIG. 33C is a plan view.
  • the image, (d) of FIG. 33 is an image in a side view.
  • a plurality of modified spots 13 were formed. Specifically, first, the distance between adjacent condensing points C in the Y direction is 8 ⁇ m, the pulse pitch of the laser light L is 5 ⁇ m, and the pulse energy of the laser light L is 0.1 ⁇ J.
  • a plurality of rows of reforming spots 13 were formed such that each row was positioned at the center between the rows of reforming spots 13.
  • the extension amount of the crack 14 extending from the modified spot 13 to the incident side of the laser light L and the opposite side thereof was about 60 ⁇ m.
  • the modified spots 13b are formed along the virtual surface 15 so as not to overlap the modified spots 13a and the cracks 14a already formed along the virtual surface 15 (( 1st Example, 2nd Example, and 3rd Example), it turned out that the extension amount of the crack 14 extended from the modification spot 13 to the incident side of the laser beam L and the opposite side is suppressed.
  • the modified surface 13 is formed on the virtual surface 15 so as not to overlap the modified spots 13a and 13b already formed along the virtual surface 15. If a plurality of modified spots 13 are formed along the lines (second and third embodiments), it becomes easy to form a crack over the virtual surface 15.
  • the object 11 of the laser processing method and the semiconductor member manufacturing method of the second embodiment is a GaN wafer (semiconductor wafer, semiconductor object) 30 formed of GaN into a disk shape, for example. ..
  • the GaN wafer 30 has a diameter of 2 inches and the GaN wafer 30 has a thickness of 100 ⁇ m.
  • the laser processing method and the semiconductor member manufacturing method of the second embodiment are carried out to cut out a plurality of semiconductor devices (semiconductor members) 40 from the GaN wafer 30.
  • the outer shape of the GaN substrate portion of the semiconductor device 40 is 1 mm ⁇ 1 mm, and the thickness of the GaN substrate portion of the semiconductor device 40 is several tens ⁇ m.
  • each of the plurality of virtual surfaces 15 is a surface facing the surface 30a of the GaN wafer 30 inside the GaN wafer 30, and is set so as to be aligned in the direction in which the surface 30a extends.
  • each of the plurality of virtual surfaces 15 is a surface parallel to the surface 30a and has, for example, a rectangular shape.
  • Each of the plurality of virtual planes 15 is set to be arranged two-dimensionally in a direction parallel to the orientation flat 31 of the GaN wafer 30 and a direction perpendicular to the orientation flat 31.
  • a plurality of peripheral regions 16 are set so as to surround each of the plurality of virtual surfaces 15. That is, each of the plurality of virtual surfaces 15 does not reach the side surface 30b of the GaN wafer 30.
  • a plurality of peripheral areas 16 are provided corresponding to each of the virtual surfaces 15.
  • the width of the peripheral region 16 corresponding to each of the plurality of virtual surfaces 15 (half the distance between the adjacent virtual surfaces 15 in the present embodiment) is 30 ⁇ m or more.
  • a region surrounded by the peripheral region 16 in the GaN wafer 30 is a processing target region R in which the modified region 12 is formed.
  • the processing target region R includes the virtual surface 15.
  • the formation of the modified region 12 along each of the plurality of virtual surfaces 15 is performed in the same manner as the laser processing method and the semiconductor member manufacturing method of the first embodiment. Thereby, in the GaN wafer 30, as shown in FIG. 35, the reforming spots 13, the cracks 14, the nitrogen gas G, and the gallium are reformed along the respective virtual planes 15. Region 12 is formed. In FIG. 35, the range in which the plurality of modified spots 13 and the plurality of cracks 14 are formed is indicated by a broken line.
  • the semiconductor manufacturing apparatus forms a plurality of functional elements 32 on the surface 30a of the GaN wafer 30, as shown in FIG.
  • Each of the plurality of functional elements 32 is formed such that one functional element 32 is included in one virtual surface 15 when viewed from the thickness direction of the GaN wafer 30.
  • the functional element 32 is, for example, a light receiving element such as a photodiode, a light emitting element such as a laser diode, a circuit element such as a memory, or the like.
  • the semiconductor manufacturing apparatus functions as a heating device when forming the plurality of functional elements 32 on the surface 30a. That is, when forming the plurality of functional elements 32 on the surface 30 a, the semiconductor manufacturing apparatus heats the GaN wafer 30, and the plurality of cracks 14 extending from the plurality of modified spots 13 on each of the plurality of virtual surfaces 15 are formed. Are connected to each other, a crack 17 (that is, a crack 17 across the virtual surface 15) is formed in each of the plurality of virtual surfaces 15. In FIG. 36, the range in which the plurality of modified spots 13, the plurality of cracks 14, and the crack 17 are formed is indicated by broken lines. A heating device different from the semiconductor manufacturing device may be used.
  • the cracks 17 may be formed by connecting the plurality of cracks 14 to each other by applying some force to the GaN wafer 30 by a method other than heating. Further, by forming the plurality of modified spots 13 along the virtual surface 15, the plurality of cracks 14 may be connected to each other to form the crack 17.
  • the crack 17 can be formed by utilizing the pressure of the nitrogen gas G by heating the GaN ingot 30 and expanding the nitrogen gas.
  • the peripheral region 16 causes the crack 14 to propagate from the modified region 12 surrounded by the peripheral region 16 to the outer surface (the surface 30a and the side face 30b) of the GaN ingot 30, and other modifications adjacent to the modified region 12. Propagation of the crack 14 into the quality region 12 is prevented. Therefore, it is possible to prevent the nitrogen gas G from escaping to the outside and the adjacent other reforming region 12. Therefore, the width of the peripheral region 16 can be set to 30 ⁇ m or more.
  • the following GaN wafer 30 is obtained as a semiconductor wafer (semiconductor object).
  • the modified region 12 formed along the virtual surface 15 facing the surface 30 a and the peripheral region 16 provided so as to surround the modified region 12.
  • the reforming region 12 includes a plurality of reforming spots 13, a plurality of cracks 14 extending from the plurality of reforming spots 13, and a nitrogen gas G, respectively.
  • the plurality of modified regions 12 are provided so as to be arranged in the direction in which the surface 30a extends.
  • the peripheral region 16 is a region where the modified spot 13 is not formed, and prevents the crack 14 from propagating from the surrounding modified region 12 to the outer surface of the GaN wafer 30.
  • a plurality of peripheral regions 16 are provided corresponding to each of the plurality of modified regions 12. The peripheral region 16 prevents the crack 14 from propagating from the surrounding modified region 12 to another modified region 12 adjacent to the modified region 12.
  • the laser processing apparatus 1 cuts the GaN wafer 30 into each functional element 32.
  • a peripheral area removing step of removing the peripheral area 16 is performed.
  • a stimulus is applied to the modified region 12, and the internal pressure releasing effect of the nitrogen gas G contained in the modified region 12 is also used to peel off a part of the GaN wafer 30 along the virtual surface 15.
  • a wafer-forming step of removing the modified region 12 to form a wafer is performed on a part of the separated GaN wafer 30.
  • a plurality of semiconductor devices 40 are obtained from the GaN wafer 30 with each of the plurality of cracks 17 as a boundary. In this way, the GaN wafer 30 is cut along each of the plurality of virtual planes 15.
  • the GaN wafer 30 may be cut into each functional element 32 by mechanical processing (for example, blade dicing) other than laser processing.
  • the laser processing step is the laser processing method of the second embodiment. Further, among the above steps, the steps up to the step of obtaining the plurality of semiconductor devices 40 from the GaN wafer 30 with each of the plurality of cracks 17 as boundaries are the semiconductor member manufacturing method of the second embodiment.
  • a plurality of virtual surfaces 15 are set so as to be arranged in the direction in which the surface 30a extends.
  • a plurality of modified regions 12 and peripheral regions 16 are provided corresponding to each of the plurality of virtual surfaces 15.
  • the peripheral region 16 prevents the crack 14 from propagating from the surrounding modified region 12 to another modified region 12 adjacent to the modified region 12. According to this, a plurality of semiconductor devices 40 can be obtained from one GaN wafer 30. Further, since the peripheral region 16 prevents the crack 14 from propagating from the reforming region 12 to another reforming region 12, the nitrogen gas G escapes from the reforming region 12 to the other reforming region 12. This can be suppressed, and the pressure of the nitrogen gas G can be effectively increased or maintained.
  • the peripheral region 16 is removed from the GaN wafer 30 to give a stimulus to the modified region 12, and the nitrogen gas G of the modified region 12 is applied. While releasing the pressure of 1, the part of the GaN ingot 20 can be peeled off along the virtual plane 15 also by utilizing this released force.
  • the crack 14 is prevented from propagating from the modified region 12 to the outer surface of the GaN wafer 30 by the peripheral region 16, and the nitrogen gas G contained in the modified region 12 is prevented. Escape to the outside through the crack 14 is suppressed. Therefore, the pressure of the nitrogen gas G can be effectively increased or maintained. Using the internal pressure, the crack 14 can be accurately propagated along the virtual surface 15. By obtaining the GaN wafer 30 from the GaN ingot 20 with the crack 17 across the virtual plane 15 as the boundary, it is possible to obtain the suitable GaN wafer 30.
  • a plurality of modified regions 12 are provided so as to be lined up in the Z direction.
  • a plurality of peripheral regions 16 are provided corresponding to each of the plurality of modified regions 12, and prevent the crack 14 from propagating from the surrounding modified region 12 to another modified region 12 adjacent to the modified region 12. According to this, it becomes possible to obtain a plurality of semiconductor devices 40 from one GaN wafer 30. It is possible to prevent the nitrogen gas G from escaping from the reforming region 12 to another reforming region 12, and it is possible to effectively increase or maintain the pressure of the nitrogen gas G.
  • the semiconductor object according to the second embodiment may be the GaN wafer 30 in a state after being cut for each functional element 32 and before the peripheral region 16 is removed. In this case, by removing the peripheral region 16 at a desired timing, the semiconductor device 40 can be obtained at a desired timing. Since handling is possible before the semiconductor device 40 is peeled off, damage to the semiconductor device 40 can be suppressed.
  • One aspect of the present invention is not limited to the above embodiment.
  • the various numerical values regarding the laser light L are not limited to those described above.
  • the pulse energy of the laser light L is 0.1 ⁇ J to 1 ⁇ J and the pulse of the laser light L is The width may be 200 fs to 1 ns.
  • the semiconductor object processed by the laser processing method and the semiconductor member manufacturing method according to one aspect of the present invention is not limited to the GaN ingot 20 of the first embodiment and the GaN wafer 30 of the second embodiment.
  • the semiconductor member manufactured by the semiconductor member manufacturing method according to one aspect of the present invention is not limited to the GaN wafer 30 of the first embodiment and the semiconductor device 40 of the second embodiment.
  • One virtual surface may be set for one semiconductor object.
  • the material of the semiconductor object may include nitride.
  • the material of the semiconductor object may be any material that generates gas by the laser light L.
  • the formation of the plurality of modified spots 13 may be sequentially performed for each of the plurality of virtual surfaces 15 from the side opposite to the surface 20a. Further, in the above-described embodiment and modification, the formation of the plurality of modified spots 13 may be sequentially performed for each of the plurality of virtual surfaces 15 from the side opposite to the surface 20a. Further, in the above-described embodiment and modification, the laser light L may be branched by the spatial light modulator 4 and one or a plurality of modified spots 13 may be simultaneously formed on each of a plurality of virtual surfaces 15.
  • the formation of the plurality of modified spots 13 is performed along the one or more virtual surfaces 15 on the surface 20a side, and the one or more GaN. After the wafer 30 is cut out, the surface 20a of the GaN ingot 20 may be ground, and again, the plurality of modified spots 13 may be formed along the one or more virtual surfaces 15 on the surface 20a side.
  • the peripheral area removing step may be omitted.
  • the heating step may be omitted, for example, when the generated nitrogen gas G has a sufficiently high pressure.
  • the laser processing apparatus 1 is not limited to the one having the above-described configuration.
  • the laser processing device 1 may not include the spatial light modulator 4.

Abstract

A laser machining method that comprises a first step in which laser light is shined into a semiconductor object from the surface of the semiconductor object to form a modified region inside the semiconductor object along a virtual plane that faces the surface of the semiconductor object, the modified region including: a plurality of modified spots; a plurality of fissures that respectively extend from the plurality of modified spots; and gas. During the first step, a peripheral region that does not have modified spots formed therein and that blocks the advancement of the fissures from the modified region toward the outer surface of the semiconductor object is provided to the semiconductor object so as to surround the modified region.

Description

レーザ加工方法、半導体部材製造方法、及び半導体対象物Laser processing method, semiconductor member manufacturing method, and semiconductor object
　本発明の一側面は、レーザ加工方法、半導体部材製造方法、及び半導体対象物に関する。 One aspect of the present invention relates to a laser processing method, a semiconductor member manufacturing method, and a semiconductor object.
　半導体インゴット等の半導体対象物にレーザ光を照射することにより、半導体対象物の内部に改質領域を形成し、改質領域に沿って半導体対象物から半導体ウェハ等の半導体部材を切り出す加工方法が知られている（例えば、特許文献１，２参照）。 By irradiating a semiconductor object such as a semiconductor ingot with laser light, a modified region is formed inside the semiconductor object, and a processing method for cutting a semiconductor member such as a semiconductor wafer from the semiconductor object along the modified region is a method. It is known (for example, see Patent Documents 1 and 2).
特開２０１７－１８３６００号公報JP, 2017-183600, A 特開２０１７－０５７１０３号公報JP, 2017-057103, A
　上述したような加工方法では、改質領域の形成の仕方が、得られる半導体部材の状態に大きく影響する。 In the processing method as described above, the method of forming the modified region greatly affects the state of the obtained semiconductor member.
　本発明の一側面は、好適な半導体部材の取得を可能にするレーザ加工方法、半導体部材製造方法及び半導体対象物を提供することを目的とする。 One aspect of the present invention is to provide a laser processing method, a semiconductor member manufacturing method, and a semiconductor object that enable suitable acquisition of a semiconductor member.
　本発明の一側面に係るレーザ加工方法は、半導体対象物の表面から半導体対象物の内部にレーザ光を入射させることにより、半導体対象物の内部において、複数の改質スポットと複数の改質スポットからそれぞれ延びる複数の亀裂とガスとを含む改質領域を、表面に対向する仮想面に沿って形成する第１工程を備え、第１工程では、改質スポットが形成されていない領域であって当該改質領域から半導体対象物の外面への亀裂の進展を阻む周縁領域を、当該改質領域を囲うように半導体対象物に設ける。 A laser processing method according to one aspect of the present invention, a plurality of modified spots and a plurality of modified spots inside the semiconductor object by causing a laser beam to enter the inside of the semiconductor object from the surface of the semiconductor object. A first step of forming a modified region containing a plurality of cracks and a gas each extending from the surface along a virtual surface facing the surface, and in the first step, a modified spot is not formed. A peripheral region that prevents cracks from propagating from the modified region to the outer surface of the semiconductor object is provided in the semiconductor object so as to surround the modified region.
　このレーザ加工方法では、第１工程において、改質領域から半導体対象物の外面へ亀裂が進展することを周縁領域によって阻むことができ、改質領域に含まれるガスが亀裂を介して外部へ逃げてしまうことを抑制することができる。よって、ガスの圧力（内圧）を効果的に上昇ないし維持させることが可能となる。その結果、当該内圧を利用し、仮想面に渡る亀裂を容易に形成することが可能となる。仮想面に渡る亀裂を境界として半導体対象物から半導体部材を取得することにより、好適な半導体部材の取得が可能となる。 In this laser processing method, in the first step, it is possible to prevent the crack from propagating from the modified region to the outer surface of the semiconductor object by the peripheral region, and the gas contained in the modified region escapes to the outside through the crack. It can be suppressed. Therefore, it is possible to effectively increase or maintain the gas pressure (internal pressure). As a result, it is possible to easily form a crack across the virtual surface by using the internal pressure. By obtaining the semiconductor member from the semiconductor object with the crack extending over the virtual surface as the boundary, it is possible to obtain a suitable semiconductor member.
　本発明の一側面に係るレーザ加工方法では、周縁領域は、表面に対向する方向から見て、改質領域を囲う枠状を呈していてもよい。このような周縁領域を形成することによって、半導体対象物の外面への亀裂の進展を効果的に阻むことができる。 In the laser processing method according to one aspect of the present invention, the peripheral area may have a frame shape surrounding the modified area when viewed from the direction facing the surface. By forming such a peripheral region, it is possible to effectively prevent the propagation of cracks to the outer surface of the semiconductor object.
　本発明の一側面に係るレーザ加工方法では、半導体対象物の材料は、窒化物を含んでいてもよい。この場合、第１工程において、半導体対象物の内部にレーザ光を入射させることにより、半導体対象物を分解して窒素ガスを発生させることができる。 In the laser processing method according to one aspect of the present invention, the material of the semiconductor object may include nitride. In this case, in the first step, it is possible to decompose the semiconductor object and generate nitrogen gas by making laser light enter the inside of the semiconductor object.
　本発明の一側面に係るレーザ加工方法は、ガスを外部へ逃がす孔を周縁領域に形成する工程を備えていてもよい。これによれば、ガスの圧力の上昇で歪が半導体対象物に加わる場合に、ガスを外部へ逃がして当該歪を抑制することが可能となる。 The laser processing method according to one aspect of the present invention may include a step of forming a hole in the peripheral area for allowing gas to escape to the outside. According to this, when strain is applied to the semiconductor object due to the increase in gas pressure, the gas can be released to the outside and the strain can be suppressed.
　本発明の一側面に係る半導体部材製造方法は、上記のレーザ加工方法を含む製造方法であって、仮想面に渡る亀裂を境界として半導体対象物から半導体部材を取得する第２工程を備える。 A semiconductor member manufacturing method according to one aspect of the present invention is a manufacturing method including the laser processing method described above, and includes a second step of acquiring a semiconductor member from a semiconductor object with a crack across a virtual surface as a boundary.
　この半導体部材製造方法においても、上記レーザ加工方法を含むことから、改質領域に含まれるガスが亀裂を介して外部へ逃げてしまうことを抑制することができ、ガスの圧力（内圧）を効果的に上昇ないし維持させることが可能となる。当該内圧を利用し、仮想面に渡る亀裂を容易に形成することが可能となる。仮想面に渡る亀裂を境界として半導体対象物から半導体部材を取得することにより、好適な半導体部材の取得が可能となる。 Also in this semiconductor member manufacturing method, since the laser processing method is included, it is possible to prevent the gas contained in the modified region from escaping to the outside through the cracks, and the gas pressure (internal pressure) is effectively reduced. It is possible to raise or maintain it. By utilizing the internal pressure, it becomes possible to easily form a crack over the virtual surface. By obtaining the semiconductor member from the semiconductor object with the crack extending over the virtual surface as the boundary, it is possible to obtain a suitable semiconductor member.
　本発明の一側面に係る半導体部材製造方法では、仮想面は、表面に対向する方向に並ぶように複数設定され、改質領域及び周縁領域は、複数の仮想面のそれぞれに対応して複数設けられ、周縁領域は、囲う改質領域から当該改質領域に隣接する他の改質領域への亀裂の進展を阻んでいてもよい。これによれば、１つの半導体対象物から複数の半導体部材の取得が可能となる。また、周縁領域によって改質領域から他の改質領域への亀裂の進展が阻まれていることから、改質領域から他の改質領域へガスが逃げてしまうことを抑制することができ、ガスの圧力を効果的に上昇ないし維持させることが可能となる。 In the method of manufacturing a semiconductor member according to one aspect of the present invention, a plurality of virtual surfaces are set so as to be aligned in a direction facing the surface, and a plurality of modified regions and peripheral regions are provided corresponding to each of the plurality of virtual surfaces. The peripheral region may prevent the propagation of cracks from the surrounding modified region to another modified region adjacent to the modified region. According to this, a plurality of semiconductor members can be obtained from one semiconductor object. Further, since the cracks are prevented from propagating from the reforming region to the other reforming regions by the peripheral region, it is possible to prevent the gas from escaping from the reforming region to the other reforming region, It is possible to effectively increase or maintain the gas pressure.
　本発明の一側面に係る半導体部材製造方法では、半導体対象物は、半導体インゴットであり、半導体部材は、半導体ウェハであってもよい。これによれば、１つの半導体インゴットから複数の半導体ウェハを取得することが可能となる。 In the semiconductor member manufacturing method according to one aspect of the present invention, the semiconductor object may be a semiconductor ingot, and the semiconductor member may be a semiconductor wafer. According to this, it becomes possible to obtain a plurality of semiconductor wafers from one semiconductor ingot.
　本発明の一側面に係る半導体部材製造方法では、仮想面は、表面が延在する方向に並ぶように複数設定され、改質領域及び周縁領域は、複数の仮想面のそれぞれに対応して複数設けられ、周縁領域は、囲う改質領域から当該改質領域に隣接する他の改質領域への亀裂の進展を阻んでいてもよい。これによれば、１つの半導体対象物から複数の半導体部材の取得が可能となる。また、周縁領域によって改質領域から他の改質領域への亀裂の進展が阻まれていることから、改質領域から他の改質領域へガスが逃げてしまうことを抑制することができ、ガスの圧力を効果的に上昇ないし維持させることが可能となる。 In the semiconductor member manufacturing method according to one aspect of the present invention, a plurality of virtual surfaces are set so as to be aligned in the direction in which the surface extends, and a plurality of modified regions and peripheral regions are provided corresponding to each of the plurality of virtual surfaces. The peripheral region, which is provided, may prevent a crack from propagating from the surrounding modified region to another modified region adjacent to the modified region. According to this, a plurality of semiconductor members can be obtained from one semiconductor object. Further, since the cracks are prevented from propagating from the reforming region to the other reforming regions by the peripheral region, it is possible to prevent the gas from escaping from the reforming region to the other reforming region, It is possible to effectively increase or maintain the gas pressure.
　本発明の一側面に係る半導体部材製造方法では、半導体対象物は、半導体ウェハであり、半導体部材は、半導体デバイスであってもよい。これによれば、１つの半導体ウェハか複数の半導体デバイスを取得することが可能となる。 In the method of manufacturing a semiconductor member according to one aspect of the present invention, the semiconductor object may be a semiconductor wafer, and the semiconductor member may be a semiconductor device. This makes it possible to obtain one semiconductor wafer or a plurality of semiconductor devices.
　本発明の一側面に係る半導体部材製造方法では、第１工程の後、半導体対象物を加熱することにより、ガスを膨張させて、亀裂を仮想面に沿って進展させる工程を備えていてもよい。この場合、仮想面に渡る亀裂を確実に形成することができる。 The semiconductor member manufacturing method according to one aspect of the present invention may include, after the first step, a step of heating the semiconductor object to expand the gas and propagate the crack along the virtual surface. .. In this case, it is possible to reliably form a crack across the virtual surface.
　本発明の一側面に係る半導体部材製造方法において、第２工程では、改質領域に外部から刺激を付与することで、半導体対象物の一部を仮想面に沿って剥離してもよい。これによれば、改質領域のガスの圧力を解放しつつ、この解放される力も利用して半導体対象物の一部を剥離することができる。 In the semiconductor member manufacturing method according to one aspect of the present invention, in the second step, a part of the semiconductor object may be peeled off along the virtual surface by applying a stimulus to the modified region from the outside. According to this, while releasing the pressure of the gas in the reforming region, a part of the semiconductor object can be peeled off by also utilizing this released force.
　本発明の一側面に係る半導体部材製造方法において、第２工程では、半導体対象物から周縁領域を除去することで、半導体対象物の一部を仮想面に沿って剥離してもよい。これによれば、改質領域のガスの圧力を解放しつつ、この解放される力も利用して半導体対象物の一部を剥離することができる。 In the method for manufacturing a semiconductor member according to one aspect of the present invention, in the second step, a peripheral region may be removed from the semiconductor object to peel off a part of the semiconductor object along the virtual surface. According to this, while releasing the pressure of the gas in the reforming region, a part of the semiconductor object can be peeled off by also utilizing this released force.
　本発明の一側面に係る半導体対象物は、表面を有する半導体対象物であって、半導体対象物の内部において、表面に対向する仮想面に沿って形成された改質領域と、改質領域を囲うように設けられた周縁領域と、を備え、改質領域は、複数の改質スポットと複数の改質スポットからそれぞれ延びる複数の亀裂とガスとを含み、周縁領域は、改質スポットが形成されていない領域であって、囲う改質領域から半導体対象物の外面への亀裂の進展を阻む。 A semiconductor object according to one aspect of the present invention is a semiconductor object having a surface, and inside the semiconductor object, a modified region formed along a virtual surface facing the surface and a modified region are provided. A peripheral region provided so as to surround the reforming region includes a plurality of reforming spots and a plurality of cracks and gases respectively extending from the plurality of reforming spots, and the reforming spot is formed in the peripheral region. The undeformed region prevents the propagation of cracks from the surrounding modified region to the outer surface of the semiconductor object.
　本発明の一側面に係る半導体対象物では、改質領域から半導体対象物の外面へ亀裂が進展することが周縁領域によって阻まれており、改質領域に含まれるガスが亀裂を介して外部へ逃げてしまうことが抑制されている。よって、ガスの圧力（内圧）を効果的に上昇ないし維持させることが可能となる。当該内圧を利用し、仮想面に沿って亀裂を精度よく進展させることが可能となる。したがって、仮想面に渡る亀裂を境界として半導体対象物から半導体部材を取得することにより、好適な半導体部材の取得が可能となる。 In the semiconductor object according to one aspect of the present invention, a crack is prevented from propagating from the modified region to the outer surface of the semiconductor object by the peripheral region, and the gas contained in the modified region is exposed to the outside through the crack. The escape is suppressed. Therefore, it is possible to effectively increase or maintain the gas pressure (internal pressure). By utilizing the internal pressure, it becomes possible to accurately propagate the crack along the virtual surface. Therefore, by obtaining the semiconductor member from the semiconductor object with the crack extending over the virtual plane as the boundary, it is possible to obtain a suitable semiconductor member.
　本発明の一側面に係る半導体対象物は、半導体インゴットであって、改質領域は、表面に対向する方向に並ぶように複数設けられ、周縁領域は、複数の改質領域のそれぞれに対応して複数設けられ、周縁領域は、囲う改質領域から当該改質領域に隣接する他の改質領域への亀裂の進展を阻んでもよい。これによれば、１つの半導体インゴットから複数の半導体ウェハを取得することが可能となる。周縁領域によって改質領域から他の改質領域への亀裂の進展が阻まれていることから、改質領域から他の改質領域へガスが逃げてしまうことを抑制することができ、ガスの圧力を効果的に上昇ないし維持させることが可能となる。 A semiconductor object according to one aspect of the present invention is a semiconductor ingot, a plurality of modified regions are provided so as to be arranged in a direction facing a surface, and a peripheral region corresponds to each of the plurality of modified regions. The plurality of peripheral regions may prevent the crack from propagating from the surrounding modified region to another modified region adjacent to the modified region. According to this, it becomes possible to obtain a plurality of semiconductor wafers from one semiconductor ingot. Since the peripheral region prevents the cracks from propagating from the reforming region to another reforming region, it is possible to prevent the gas from escaping from the reforming region to another reforming region. It is possible to effectively raise or maintain the pressure.
　本発明の一側面に係る半導体対象物は、半導体ウェハであって、改質領域は、表面が延在する方向に並ぶように複数設けられ、周縁領域は、複数の仮想面のそれぞれに対応して複数設けられ、周縁領域は、囲う改質領域から当該改質領域に隣接する他の改質領域への亀裂の進展を阻んでもよい。これによれば、１つの半導体ウェハから複数の半導体デバイスを取得することが可能となる。周縁領域によって改質領域から他の改質領域への亀裂の進展が阻まれていることから、改質領域から他の改質領域へガスが逃げてしまうことを抑制することができ、ガスの圧力を効果的に上昇ないし維持させることが可能となる。 A semiconductor object according to one aspect of the present invention is a semiconductor wafer, a plurality of modified regions are provided so as to be arranged in a direction in which a surface extends, and a peripheral region corresponds to each of a plurality of virtual planes. The plurality of peripheral regions may prevent the crack from propagating from the surrounding modified region to another modified region adjacent to the modified region. According to this, it becomes possible to acquire a plurality of semiconductor devices from one semiconductor wafer. Since the peripheral region prevents the cracks from propagating from the reforming region to the other reforming region, it is possible to prevent the gas from escaping from the reforming region to the other reforming region. It is possible to effectively raise or maintain the pressure.
　本発明の一側面によれば、好適な半導体部材の取得を可能にするレーザ加工方法、半導体部材製造方法及び半導体対象物を提供することが可能となる。 According to one aspect of the present invention, it is possible to provide a laser processing method, a semiconductor member manufacturing method, and a semiconductor object that enable suitable acquisition of a semiconductor member.
図１は、実施形態のレーザ加工装置の構成図である。FIG. 1 is a configuration diagram of a laser processing apparatus according to an embodiment. 図２は、第１実施形態のレーザ加工方法及び半導体部材製造方法の対象物であるＧａＮインゴットの側面図である。FIG. 2 is a side view of a GaN ingot which is an object of the laser processing method and the semiconductor member manufacturing method of the first embodiment. 図３は、図２に示されるＧａＮインゴットの平面図である。FIG. 3 is a plan view of the GaN ingot shown in FIG. 図４は、第１実施形態のレーザ加工方法及び半導体部材製造方法の加熱工程におけるＧａＮインゴットの横断面図である。FIG. 4 is a cross-sectional view of the GaN ingot in the heating process of the laser processing method and the semiconductor member manufacturing method of the first embodiment. 図５は、第１実施形態のレーザ加工方法及び半導体部材製造方法の加熱工程におけるＧａＮインゴットの横断面図である。FIG. 5 is a cross-sectional view of the GaN ingot in the heating process of the laser processing method and the semiconductor member manufacturing method of the first embodiment. 図６は、第１実施形態のレーザ加工方法及び半導体部材製造方法の加熱工程におけるＧａＮインゴットの横断面図である。FIG. 6 is a cross-sectional view of the GaN ingot in the heating process of the laser processing method and the semiconductor member manufacturing method of the first embodiment. 図７は、第１実施形態のレーザ加工方法及び半導体部材製造方法の加熱工程におけるＧａＮインゴットの横断面図である。FIG. 7 is a cross-sectional view of the GaN ingot in the heating process of the laser processing method and the semiconductor member manufacturing method of the first embodiment. 図８は、第１実施形態のレーザ加工方法及び半導体部材製造方法の加熱工程後におけるＧａＮインゴットの側面図である。FIG. 8 is a side view of the GaN ingot after the heating step of the laser processing method and the semiconductor member manufacturing method of the first embodiment. 図９（ａ）は、第１実施形態のレーザ加工方法及び半導体部材製造方法の加熱工程におけるＧａＮインゴットの第１例を示す写真図である。図９（ｂ）は、第１実施形態のレーザ加工方法及び半導体部材製造方法の加熱工程におけるＧａＮインゴットの第２例を示す写真図である。図９（ｃ）は、第１実施形態のレーザ加工方法及び半導体部材製造方法の加熱工程におけるＧａＮインゴットの第３例を示す写真図である。図９（ｄ）は、第１実施形態のレーザ加工方法及び半導体部材製造方法の加熱工程におけるＧａＮインゴットの第４例を示す写真図である。FIG. 9A is a photograph showing a first example of a GaN ingot in the heating step of the laser processing method and the semiconductor member manufacturing method of the first embodiment. FIG. 9B is a photograph showing a second example of the GaN ingot in the heating step of the laser processing method and the semiconductor member manufacturing method of the first embodiment. FIG. 9C is a photograph showing a third example of the GaN ingot in the heating step of the laser processing method and the semiconductor member manufacturing method of the first embodiment. FIG. 9D is a photograph showing a fourth example of the GaN ingot in the heating step of the laser processing method and the semiconductor member manufacturing method of the first embodiment. 図１０は、第１実施形態のレーザ加工方法及び半導体部材製造方法の周縁領域除去工程におけるＧａＮインゴットの側面図である。FIG. 10 is a side view of the GaN ingot in the peripheral region removing step of the laser processing method and the semiconductor member manufacturing method of the first embodiment. 図１１は、第１実施形態のレーザ加工方法及び半導体部材製造方法の刺激付与工程におけるＧａＮインゴットの側面図である。FIG. 11 is a side view of the GaN ingot in the stimulation applying step of the laser processing method and the semiconductor member manufacturing method of the first embodiment. 図１２（ａ）は、第１実施形態のレーザ加工方法及び半導体部材製造方法における刺激付与工程後のＧａＮインゴットの側面図である。図１２（ｂ）は、第１実施形態のレーザ加工方法及び半導体部材製造方法で得られたＧａＮウェハの側面図である。FIG. 12A is a side view of the GaN ingot after the stimulation applying step in the laser processing method and the semiconductor member manufacturing method of the first embodiment. FIG. 12B is a side view of the GaN wafer obtained by the laser processing method and the semiconductor member manufacturing method of the first embodiment. 図１３は、変形例のレーザ加工方法及び半導体部材製造方法の加熱工程におけるＧａＮインゴットの横断面図である。FIG. 13 is a cross-sectional view of a GaN ingot in the heating process of the modified laser processing method and semiconductor member manufacturing method. 図１４は、変形例のレーザ加工方法及び半導体部材製造方法の周縁領域除去工程におけるＧａＮインゴットの側面図である。FIG. 14 is a side view of the GaN ingot in the peripheral region removing step of the modified laser processing method and semiconductor member manufacturing method. 図１５は、変形例のレーザ加工方法及び半導体部材製造方法の一工程におけるＧａＮインゴットの一部分の縦断面図である。FIG. 15 is a vertical cross-sectional view of a part of a GaN ingot in one step of the laser processing method and the semiconductor member manufacturing method of the modified example. 図１６は、変形例のレーザ加工方法及び半導体部材製造方法の一工程におけるＧａＮインゴットの一部分の横断面図である。FIG. 16 is a cross-sectional view of a part of a GaN ingot in one step of the laser processing method and the semiconductor member manufacturing method of the modified example. 図１７は、変形例のレーザ加工方法及び半導体部材製造方法の一工程におけるＧａＮインゴットの一部分の縦断面図である。FIG. 17 is a vertical cross-sectional view of a part of the GaN ingot in one step of the laser processing method and the semiconductor member manufacturing method of the modified example. 図１８は、変形例のレーザ加工方法及び半導体部材製造方法の一工程におけるＧａＮインゴットの一部分の横断面図である。FIG. 18 is a cross-sectional view of a part of a GaN ingot in one step of the laser processing method and the semiconductor member manufacturing method of the modified example. 図１９は、変形例のレーザ加工方法及び半導体部材製造方法の一工程におけるＧａＮインゴットの一部分の縦断面図である。FIG. 19 is a vertical cross-sectional view of a portion of a GaN ingot in one step of the laser processing method and semiconductor member manufacturing method of the modification. 図２０は、変形例のレーザ加工方法及び半導体部材製造方法の一工程におけるＧａＮインゴットの一部分の横断面図である。FIG. 20 is a cross-sectional view of a part of a GaN ingot in one step of the laser processing method and the semiconductor member manufacturing method of the modified example. 図２１は、変形例のレーザ加工方法及び半導体部材製造方法の一工程におけるＧａＮインゴットの一部分の縦断面図である。FIG. 21 is a vertical cross-sectional view of a part of a GaN ingot in one step of the laser processing method and the semiconductor member manufacturing method of the modified example. 図２２は、変形例のレーザ加工方法及び半導体部材製造方法の一工程におけるＧａＮインゴットの一部分の横断面図である。FIG. 22 is a cross-sectional view of a part of a GaN ingot in one step of the laser processing method and the semiconductor member manufacturing method of the modified example. 図２３は、一例のレーザ加工方法及び半導体部材製造方法によって形成されたＧａＮウェハの剥離面の画像である。FIG. 23 is an image of the separated surface of the GaN wafer formed by the laser processing method and the semiconductor member manufacturing method of an example. 図２４（ａ）は、図２３に示される剥離面の高さプロファイルである。図２４（ｂ）は、図２３に示される剥離面の高さプロファイルである。FIG. 24A is a height profile of the peeled surface shown in FIG. FIG. 24B is a height profile of the peeled surface shown in FIG. 図２５は、他の例のレーザ加工方法及び半導体部材製造方法によって形成されたＧａＮウェハの剥離面の画像である。FIG. 25 is an image of the separated surface of the GaN wafer formed by the laser processing method and the semiconductor member manufacturing method of another example. 図２６（ａ）は、図２５に示される剥離面の高さプロファイルである。図２６（ｂ）は、図２５に示される剥離面の高さプロファイルである。FIG. 26A is a height profile of the peeled surface shown in FIG. FIG. 26B is a height profile of the peeled surface shown in FIG. 図２７は、一例のレーザ加工方法及び半導体部材製造方法による剥離面の形成原理を説明するための模式図である。FIG. 27 is a schematic diagram for explaining the principle of forming a peeled surface by the laser processing method and the semiconductor member manufacturing method as an example. 図２８は、他の例のレーザ加工方法及び半導体部材製造方法による剥離面の形成原理を説明するための模式図である。FIG. 28 is a schematic diagram for explaining a principle of forming a peeled surface by a laser processing method and a semiconductor member manufacturing method of another example. 図２９（ａ）は、一例のレーザ加工方法及び半導体部材製造方法の途中で形成された亀裂の画像である。図２９（ｂ）は、図２９の（ａ）における矩形枠内の拡大画像である。FIG. 29A is an image of a crack formed during the laser processing method and the semiconductor member manufacturing method of an example. FIG. 29( b) is an enlarged image within the rectangular frame in FIG. 29( a ). 図３０（ａ）は、他の例のレーザ加工方法及び半導体部材製造方法の途中で形成された亀裂の画像である。図３０（ｂ）は、図３０の（ａ）における矩形枠内の拡大画像である。FIG. 30A is an image of a crack formed during the laser processing method and the semiconductor member manufacturing method of another example. FIG. 30(b) is an enlarged image within the rectangular frame in FIG. 30(a). 図３１は、比較例のレーザ加工方法及び半導体部材製造方法によって形成された改質スポット及び亀裂の画像である。FIG. 31 is an image of modified spots and cracks formed by the laser processing method and the semiconductor member manufacturing method of the comparative example. 図３２（ａ）は、第１実施例のレーザ加工方法及び半導体部材製造方法によって形成された改質スポット及び亀裂の平面視での画像である。図３２（ｂ）は、第１実施例のレーザ加工方法及び半導体部材製造方法によって形成された改質スポット及び亀裂の側面視での画像である。FIG. 32A is an image in plan view of modified spots and cracks formed by the laser processing method and the semiconductor member manufacturing method of the first embodiment. FIG. 32B is a side view image of modified spots and cracks formed by the laser processing method and the semiconductor member manufacturing method of the first embodiment. 図３３（ａ）は、第２実施例のレーザ加工方法及び半導体部材製造方法によって形成された改質スポット及び亀裂の平面視での画像である。図３３（ｂ）は、第２実施例のレーザ加工方法及び半導体部材製造方法によって形成された改質スポット及び亀裂の側面視での画像である。図３３（ｃ）は、第３実施例のレーザ加工方法及び半導体部材製造方法によって形成された改質スポット及び亀裂の平面視での画像である。図３３（ｄ）は、第３実施例のレーザ加工方法及び半導体部材製造方法によって形成された改質スポット及び亀裂の側面視での画像である。FIG. 33A is an image in plan view of modified spots and cracks formed by the laser processing method and the semiconductor member manufacturing method of the second embodiment. FIG. 33B is a side view image of modified spots and cracks formed by the laser processing method and the semiconductor member manufacturing method of the second embodiment. FIG. 33C is an image in plan view of modified spots and cracks formed by the laser processing method and the semiconductor member manufacturing method of the third embodiment. FIG. 33D is a side view image of modified spots and cracks formed by the laser processing method and the semiconductor member manufacturing method of the third embodiment. 図３４は、第２実施形態のレーザ加工方法及び半導体部材製造方法の対象物であるＧａＮウェハの平面図である。FIG. 34 is a plan view of a GaN wafer which is an object of the laser processing method and the semiconductor member manufacturing method of the second embodiment. 図３５は、第２実施形態のレーザ加工方法及び半導体部材製造方法の一工程におけるＧａＮウェハの一部分の側面図である。FIG. 35 is a side view of a part of the GaN wafer in one step of the laser processing method and the semiconductor member manufacturing method of the second embodiment. 図３６は、第２実施形態のレーザ加工方法及び半導体部材製造方法の一工程におけるＧａＮウェハの一部分の側面図である。FIG. 36 is a side view of a part of the GaN wafer in one step of the laser processing method and the semiconductor member manufacturing method of the second embodiment. 図３７は、第２実施形態のレーザ加工方法及び半導体部材製造方法の一工程における半導体デバイスの側面図である。FIG. 37 is a side view of the semiconductor device in one step of the laser processing method and the semiconductor member manufacturing method of the second embodiment.
　以下、実施形態について、図面を参照して詳細に説明する。なお、各図において同一又は相当部分には同一符号を付し、重複する説明を省略する。
［レーザ加工装置の構成］ Hereinafter, embodiments will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts will be denoted by the same reference symbols and redundant description will be omitted.
[Configuration of laser processing equipment]
　図１に示されるように、レーザ加工装置１は、ステージ２と、光源３と、空間光変調器４と、集光レンズ５と、制御部６と、を備えている。レーザ加工装置１は、対象物１１にレーザ光Ｌを照射することにより、対象物１１に改質領域１２を形成する装置である。以下、第１水平方向をＸ方向といい、第１水平方向に垂直な第２水平方向をＹ方向という。また、鉛直方向をＺ方向という。 As shown in FIG. 1, the laser processing apparatus 1 includes a stage 2, a light source 3, a spatial light modulator 4, a condenser lens 5, and a control unit 6. The laser processing apparatus 1 is an apparatus that forms a modified region 12 on the object 11 by irradiating the object 11 with a laser beam L. Hereinafter, the first horizontal direction will be referred to as the X direction, and the second horizontal direction perpendicular to the first horizontal direction will be referred to as the Y direction. The vertical direction is called the Z direction.
　ステージ２は、例えば対象物１１に貼り付けられたフィルムを吸着することにより、対象物１１を支持する。本実施形態では、ステージ２は、Ｘ方向及びＹ方向のそれぞれに沿って移動可能である。また、ステージ２は、Ｚ方向に平行な軸線を中心線として回転可能である。 The stage 2 supports the target object 11 by, for example, adsorbing a film attached to the target object 11. In the present embodiment, the stage 2 is movable along each of the X direction and the Y direction. Further, the stage 2 can rotate about an axis parallel to the Z direction as a center line.
　光源３は、例えばパルス発振方式によって、対象物１１に対して透過性を有するレーザ光Ｌを出力する。空間光変調器４は、光源３から出力されたレーザ光Ｌを変調する。空間光変調器４は、例えば反射型液晶（ＬＣＯＳ：Liquid　Crystal　on　Silicon）の空間光変調器（ＳＬＭ：Spatial　Light　Modulator）である。集光レンズ５は、空間光変調器４によって変調されたレーザ光Ｌを集光する。本実施形態では、空間光変調器４及び集光レンズ５は、レーザ照射ユニットとして、Ｚ方向に沿って移動可能である。 The light source 3 outputs a laser beam L that is transparent to the object 11 by using, for example, a pulse oscillation method. The spatial light modulator 4 modulates the laser light L output from the light source 3. The spatial light modulator 4 is, for example, a reflective liquid crystal (LCOS: Liquid Crystal on Silicon) spatial light modulator (SLM: Spatial Light Modulator). The condenser lens 5 condenses the laser light L modulated by the spatial light modulator 4. In this embodiment, the spatial light modulator 4 and the condenser lens 5 are movable as a laser irradiation unit along the Z direction.
　ステージ２に支持された対象物１１の内部にレーザ光Ｌが集光されると、レーザ光Ｌの集光点Ｃに対応する部分においてレーザ光Ｌが特に吸収され、対象物１１の内部に改質領域１２が形成される。改質領域１２は、密度、屈折率、機械的強度、その他の物理的特性が周囲の非改質領域とは異なる領域である。改質領域１２としては、例えば、溶融処理領域、クラック領域、絶縁破壊領域、屈折率変化領域等がある。 When the laser light L is condensed inside the target object 11 supported by the stage 2, the laser light L is particularly absorbed at a portion corresponding to the condensing point C of the laser light L, and the inside of the target object 11 is modified. A quality region 12 is formed. The modified region 12 is a region in which density, refractive index, mechanical strength, and other physical properties are different from those of the surrounding unmodified region. The modified region 12 includes, for example, a melt-processed region, a crack region, a dielectric breakdown region, and a refractive index change region.
　一例として、ステージ２をＸ方向に沿って移動させ、対象物１１に対して集光点ＣをＸ方向に沿って相対的に移動させると、複数の改質スポット１３がＸ方向に沿って１列に並ぶように形成される。１つの改質スポット１３は、１パルスのレーザ光Ｌの照射によって形成される。１列の改質領域１２は、１列に並んだ複数の改質スポット１３の集合である。隣り合う改質スポット１３は、対象物１１に対する集光点Ｃの相対的な移動速度及びレーザ光Ｌの繰り返し周波数によって、互いに繋がる場合も、互いに離れる場合もある。 As an example, when the stage 2 is moved along the X direction and the condensing point C is moved relative to the target object 11 along the X direction, a plurality of modified spots 13 are moved along the X direction by 1. It is formed so as to line up in a row. One modified spot 13 is formed by irradiation with one pulse of laser light L. The one-row reforming region 12 is a set of a plurality of reforming spots 13 arranged in one row. The adjacent modified spots 13 may be connected to each other or may be separated from each other depending on the relative moving speed of the condensing point C with respect to the object 11 and the repetition frequency of the laser light L.
　制御部６は、ステージ２、光源３、空間光変調器４及び集光レンズ５を制御する。制御部６は、プロセッサ、メモリ、ストレージ及び通信デバイス等を含むコンピュータ装置として構成されている。制御部６では、メモリ等に読み込まれたソフトウェア（プログラム）が、プロセッサによって実行され、メモリ及びストレージにおけるデータの読み出し及び書き込み、並びに、通信デバイスによる通信が、プロセッサによって制御される。これにより、制御部６は、各種機能を実現する。
［第１実施形態のレーザ加工方法及び半導体部材製造方法］ The control unit 6 controls the stage 2, the light source 3, the spatial light modulator 4, and the condenser lens 5. The control unit 6 is configured as a computer device including a processor, a memory, a storage, a communication device, and the like. In the control unit 6, the software (program) read into the memory or the like is executed by the processor, and the reading and writing of data in the memory and the storage and the communication by the communication device are controlled by the processor. Thereby, the control unit 6 realizes various functions.
[Laser Processing Method and Semiconductor Member Manufacturing Method of First Embodiment]
　第１実施形態のレーザ加工方法及び半導体部材製造方法の対象物１１は、図２及び図３に示されるように、窒化ガリウム（ＧａＮ）によって例えば矩形板状に形成されたＧａＮインゴット（半導体インゴット、半導体対象物）２０である。一例として、ＧａＮインゴット２０の幅は、縦３０ｍｍ、横３０ｍｍであり、ＧａＮインゴット２０の厚さは２ｍｍである。第１実施形態のレーザ加工方法及び半導体部材製造方法は、ＧａＮインゴット２０から複数のＧａＮウェハ（半導体ウェハ、半導体部材）３０を切り出すために実施される。一例として、ＧａＮウェハ３０の幅は、縦１０ｍｍ、横１０ｍｍであり、ＧａＮウェハ３０の厚さは１００μｍである。ＧａＮインゴット２０及びＧａＮウェハ３０の形状は特に限定されず、例えば円形板状であってもよい。 The object 11 of the laser processing method and the semiconductor member manufacturing method of the first embodiment is, as shown in FIGS. 2 and 3, a GaN ingot (semiconductor ingot, formed of gallium nitride (GaN) in a rectangular plate shape, for example. Semiconductor object) 20. As an example, the GaN ingot 20 has a width of 30 mm and a width of 30 mm, and the GaN ingot 20 has a thickness of 2 mm. The laser processing method and the semiconductor member manufacturing method of the first embodiment are performed to cut out a plurality of GaN wafers (semiconductor wafers, semiconductor members) 30 from the GaN ingot 20. As an example, the width of the GaN wafer 30 is 10 mm in length and 10 mm in width, and the thickness of the GaN wafer 30 is 100 μm. The shapes of the GaN ingot 20 and the GaN wafer 30 are not particularly limited, and may be circular plate shapes, for example.
　まず、上述したレーザ加工装置１を用いたレーザ加工工程（第１工程）を実施する。レーザ加工工程では、上述したレーザ加工装置１が、複数の仮想面１５のそれぞれに沿って改質領域１２を形成する。複数の仮想面１５のそれぞれは、ＧａＮインゴット２０の内部においてＧａＮインゴット２０の表面２０ａに対向する面であり、表面２０ａに対向する方向に並ぶように設定されている。本実施形態では、複数の仮想面１５のそれぞれは、表面２０ａに平行な面であり、例えば矩形状を呈している。複数の仮想面１５のそれぞれは、表面２０ａ側から見た場合に互いに重なるように設定されている。ＧａＮインゴット２０には、複数の仮想面１５のそれぞれを囲むように複数の周縁領域１６が設定されている。つまり、複数の仮想面１５のそれぞれは、ＧａＮインゴット２０の側面２０ｂに至っていない。一例として、隣り合う仮想面１５間の距離は１００μｍであり、周縁領域１６の幅（本実施形態では、仮想面１５の外縁と側面２０ｂとの距離）は３０μｍ以上である。ＧａＮインゴット２０において周縁領域１６で囲まれた領域は、改質領域１２を形成する対象となる加工対象領域Ｒである。加工対象領域Ｒは、仮想面１５を含む。周縁領域１６の詳細については、後述する。 First, the laser processing process (first process) using the laser processing device 1 described above is performed. In the laser processing step, the laser processing apparatus 1 described above forms the modified region 12 along each of the virtual surfaces 15. Each of the plurality of virtual surfaces 15 is a surface facing the surface 20a of the GaN ingot 20 inside the GaN ingot 20, and is set to be aligned in a direction facing the surface 20a. In the present embodiment, each of the plurality of virtual surfaces 15 is a surface parallel to the surface 20a and has, for example, a rectangular shape. Each of the plurality of virtual surfaces 15 is set so as to overlap each other when viewed from the front surface 20a side. A plurality of peripheral regions 16 are set in the GaN ingot 20 so as to surround each of the plurality of virtual surfaces 15. That is, each of the plurality of virtual surfaces 15 does not reach the side surface 20b of the GaN ingot 20. As an example, the distance between the adjacent virtual surfaces 15 is 100 μm, and the width of the peripheral region 16 (in the present embodiment, the distance between the outer edge of the virtual surface 15 and the side surface 20b) is 30 μm or more. A region surrounded by the peripheral region 16 in the GaN ingot 20 is a processing target region R in which the modified region 12 is formed. The processing target region R includes the virtual surface 15. Details of the peripheral region 16 will be described later.
　改質領域１２の形成は、例えば５３２ｎｍの波長を有するレーザ光Ｌの照射によって、表面２０ａとは反対側から１つの仮想面１５ごとに順次に実施される。改質領域１２は、複数の仮想面１５のそれぞれに対応して複数設けられている。改質領域１２の形成は、複数の仮想面１５のそれぞれにおいて同様であるため、以下、表面２０ａに最も近い仮想面１５に沿った改質領域１２の形成について、詳細に説明する。以下においては、後述する改質スポット１３ａ，１３ｂ，１３ｃ，１３ｄを包括して改質スポット１３といい、後述する亀裂１４ａ，１４ｂ，１４ｃ，１４ｄを包括して亀裂１４という場合がある。 The formation of the modified region 12 is sequentially performed for each virtual surface 15 from the side opposite to the surface 20a by irradiation with the laser light L having a wavelength of 532 nm, for example. A plurality of modified regions 12 are provided corresponding to each of the plurality of virtual surfaces 15. Since the formation of the modified region 12 is the same for each of the plurality of virtual surfaces 15, the formation of the modified region 12 along the virtual surface 15 closest to the surface 20a will be described in detail below. Hereinafter, the modified spots 13a, 13b, 13c, and 13d described later may be collectively referred to as the modified spot 13, and the cracks 14a, 14b, 14c, and 14d described later may be collectively referred to as the crack 14.
　図４に示されるように、レーザ加工装置１が、表面２０ａからＧａＮインゴット２０の内部にレーザ光Ｌを入射させながら、当該レーザ光Ｌの集光点Ｃを仮想面１５に沿ってＸ方向及びＹ方向に移動させる。これにより、ＧａＮインゴット２０における周縁領域１６に囲まれた加工対象領域Ｒに、仮想面１５に沿って改質領域１２を形成する。 As shown in FIG. 4, while the laser processing apparatus 1 makes the laser light L enter the GaN ingot 20 from the surface 20 a, the condensing point C of the laser light L is moved along the virtual plane 15 in the X direction and Move in Y direction. As a result, the modified region 12 is formed along the virtual surface 15 in the processing target region R surrounded by the peripheral region 16 of the GaN ingot 20.
　改質領域１２は、Ｘ方向及びＹ方向に並ぶ複数の改質スポット１３ａと、複数の改質スポット１３ｂからそれぞれ延びる複数の亀裂１４ｂと、レーザ光Ｌの照射でＧａＮインゴット２０が分解（化学変化）されて生じた窒素ガス（ガス）Ｇと、レーザ光Ｌの照射でＧａＮインゴット２０が分解されて析出したガリウム（析出物）と、を含む。複数の改質スポット１３ａは、仮想面１５においてマトリックス状に設けられている。複数の亀裂１４ｂは、マイクロクラックを含む。複数の亀裂１４ｂは、互いに繋がっていてもよいし、互いに繋がっていなくてもよい。窒素ガスＧは、複数の亀裂１４内に生じている。窒素ガスＧは、改質領域１２（加工対象領域Ｒ）の一又は複数箇所に、点在するように生じている。なお、図中では、改質スポット１３ａが黒四角で示されており、亀裂１４ａが延びる範囲が破線で示されている（図５及び図６でも同様）。 In the modified region 12, a plurality of modified spots 13a arranged in the X direction and the Y direction, a plurality of cracks 14b respectively extending from the plurality of modified spots 13b, and the GaN ingot 20 being decomposed by the irradiation of the laser light L (chemical change). ) Generated nitrogen gas (gas) G, and gallium (precipitate) deposited by decomposition of the GaN ingot 20 by irradiation of the laser light L. The plurality of modified spots 13a are provided in a matrix on the virtual surface 15. The plurality of cracks 14b include microcracks. The plurality of cracks 14b may be connected to each other or may not be connected to each other. The nitrogen gas G is generated in the cracks 14. The nitrogen gas G is generated so as to be scattered in one or a plurality of places in the reforming region 12 (processing target region R). In the figure, the modified spot 13a is shown by a black square, and the range in which the crack 14a extends is shown by a broken line (also in FIGS. 5 and 6).
　本実施形態において、改質領域１２の形成では、改質スポット１３ａが形成されていない領域であって当該改質領域１２からＧａＮインゴット２０の外面（表面２０ａ、表面２０ａとは反対側の他の表面２０ｃ、及び側面２０ｂ）への亀裂１４ｂの進展を阻む周縁領域１６を、当該改質領域１２を囲うようにＧａＮインゴット２０に設けている。周縁領域１６は、Ｚ方向（表面２０ａに対向する方向）から見て、改質領域１２を囲う枠状を呈する。周縁領域１６は、複数の仮想面１５のそれぞれに対応して複数設けられている。周縁領域１６は、囲う改質領域１２から当該改質領域１２に隣接する他の改質領域１２への亀裂１４ｂの進展を更に阻む。亀裂１４ｂの進展を阻むとは、亀裂１４ｂの進展を完全に阻止することに限定されず、ＧａＮインゴット２０の外面に亀裂１４ｂが極力達しないようにすること、亀裂１４ｂが進展しないようにすること、及び、亀裂１４ｂの進展を妨げることの少なくとも何れかであってもよい。 In the present embodiment, when the modified region 12 is formed, the modified spot 13a is not formed in the modified region 12 and the outer surface of the GaN ingot 20 (the surface 20a, another surface opposite to the surface 20a) from the modified region 12 is formed. The GaN ingot 20 is provided with a peripheral region 16 that prevents the crack 14b from propagating to the surface 20c and the side face 20b) so as to surround the modified region 12. The peripheral region 16 has a frame shape surrounding the modified region 12 when viewed from the Z direction (direction facing the surface 20a). A plurality of peripheral areas 16 are provided corresponding to each of the virtual surfaces 15. The peripheral region 16 further prevents the crack 14b from propagating from the surrounding modified region 12 to another modified region 12 adjacent to the modified region 12. Blocking the growth of the crack 14b is not limited to completely blocking the growth of the crack 14b, and preventing the crack 14b from reaching the outer surface of the GaN ingot 20 as much as possible, and preventing the crack 14b from growing. And/or hindering the development of the crack 14b.
　改質領域１２の形成では、加工対象領域Ｒと周縁領域１６とに対するレーザ光Ｌの照射のオンとオフとを切り替えるオンオフ照射（高精度レーザON/OFF制御）を実施することで、周縁領域１６を設けてもよい。すなわち、周縁領域１６に集光点Ｃが位置するときにはレーザ光Ｌをオフとし、周縁領域１６よりも内側（加工対象領域Ｒ）に集光点Ｃが位置するときにはレーザ光Ｌの照射をオンとしてもよい。 In the formation of the modified region 12, on-off irradiation (high-precision laser ON/OFF control) for switching the irradiation of the laser light L to the processing target region R and the peripheral region 16 between on and off is performed, and thus the peripheral region 16 is performed. May be provided. That is, the laser beam L is turned off when the converging point C is located in the peripheral region 16, and the irradiation of the laser beam L is turned on when the converging point C is located inside the peripheral region 16 (region R to be processed). Good.
　これに代えて又は加えて、改質領域１２の形成では、レーザ光Ｌの加工条件を、当該改質領域１２からＧａＮインゴット２０の外面及び／又は他の改質領域１２へ亀裂１４ｂが進展しない条件とすることで、周縁領域１６を設けてもよい。周縁領域１６を設けるための加工条件は、公知技術に基づき設定することができる。周縁領域１６を設けるための加工条件は、レーザ光Ｌのエネルギ及びパルスピッチの設定条件を含む。例えば、周縁領域１６を設けるための加工条件では、レーザ光Ｌのエネルギが所定エネルギよりも小さく、且つ、パルスピッチが所定長よりも長く設定されている。或いは、改質領域１２の形成では、ＧａＮインゴット２０の加工対象領域Ｒ以外を、レーザ入射を阻害させるようなマスクで覆うことで、周縁領域１６を設けてもよい。 Instead of or in addition to this, in the formation of the modified region 12, the crack 14b does not propagate under the processing conditions of the laser light L from the modified region 12 to the outer surface of the GaN ingot 20 and/or to the other modified region 12. The peripheral region 16 may be provided under the conditions. The processing conditions for providing the peripheral region 16 can be set based on a known technique. The processing conditions for providing the peripheral region 16 include the laser beam L energy and pulse pitch setting conditions. For example, in the processing conditions for providing the peripheral region 16, the energy of the laser light L is set to be smaller than the predetermined energy and the pulse pitch is set to be longer than the predetermined length. Alternatively, in the formation of the modified region 12, the peripheral region 16 may be provided by covering the region other than the region R to be processed of the GaN ingot 20 with a mask that blocks laser incidence.
　これらの少なくとも何れかに代えて又は加えて、改質領域１２の形成では、ＧａＮインゴット２０の表面２０ａの外縁に存在するベベル部（傾斜部又はテーパ部とも称する）を利用してレーザ光Ｌの集光を抑えることで、周縁領域１６を設けてもよい。 Instead of or in addition to at least one of these, in the formation of the modified region 12, the bevel portion (also referred to as an inclined portion or a tapered portion) existing at the outer edge of the surface 20a of the GaN ingot 20 is used to generate the laser light L. The peripheral region 16 may be provided by suppressing light collection.
　続いて、ヒータ等を備える加熱装置を用いて、ＧａＮインゴット２０を加熱する加熱工程を実施する。加熱装置は、加熱プレート、追加のレーザ加工を行う装置、ヒータ、加熱炉、ＬＤ（Laser Diode）ヒータ、レーザ装置等の光源による加熱を行う装置、超音波による加熱を行う装置、衝撃波による加熱を行う装置、及び、電磁波による加熱を行う装置等の少なくとも何れかを含んでいてもよい。 Next, a heating process for heating the GaN ingot 20 is performed using a heating device equipped with a heater or the like. The heating device includes a heating plate, a device for performing additional laser processing, a heater, a heating furnace, an LD (Laser Diode) heater, a device for heating with a light source such as a laser device, a device for heating with ultrasonic waves, and a device with shock waves for heating. It may include at least one of a device for performing heating and a device for performing heating by electromagnetic waves.
　ここで、ＧａＮインゴット２０では、改質領域１２に窒素ガスＧが含まれている。そのため、加熱工程では、ＧａＮインゴット２０を加熱することで、図５～図７に示されるように、窒素ガスＧを膨張させ、窒素ガスＧの圧力（内圧）の上昇を誘因させる。これにより、窒素ガスＧを１つに繋げると共に仮想面１５（加工対象領域Ｒ）の全域に拡げる。窒素ガスＧの圧力を利用して、仮想面１５において、複数の改質スポット１３からそれぞれ延びる複数の亀裂１４を互いに繋げる。仮想面１５に沿って複数の亀裂１４を進展させ、仮想面１５に渡る大きな亀裂１７（以下、単に「亀裂１７」という）を形成する。 Here, in the GaN ingot 20, the reformed region 12 contains the nitrogen gas G. Therefore, in the heating step, by heating the GaN ingot 20, the nitrogen gas G is expanded and the pressure (internal pressure) of the nitrogen gas G is increased as shown in FIGS. As a result, the nitrogen gas G is connected to one and spreads over the entire virtual surface 15 (processing target region R). Using the pressure of the nitrogen gas G, the plurality of cracks 14 extending from the plurality of reforming spots 13 are connected to each other on the virtual surface 15. A plurality of cracks 14 are propagated along the virtual surface 15 to form a large crack 17 (hereinafter, simply referred to as “crack 17”) across the virtual surface 15.
　図８に示されるように、仮想面１５は複数設定されていることから、加熱工程では、複数の仮想面１５のそれぞれにおいて亀裂１７を形成する。図８では、複数の改質スポット１３及び複数の亀裂１４、並びに、亀裂１７が形成される範囲が破線で示されている。亀裂１７には、溶融した析出物が入り込んでいる場合がある。亀裂１４及び亀裂１７は、以下では空隙とも称される。 As shown in FIG. 8, since a plurality of virtual surfaces 15 are set, cracks 17 are formed on each of the virtual surfaces 15 in the heating process. In FIG. 8, a range in which the plurality of modified spots 13, the plurality of cracks 14, and the crack 17 are formed is indicated by a broken line. Molten precipitates may enter the cracks 17. The cracks 14 and 17 are also referred to below as voids.
　加熱工程では、周縁領域１６によって複数の亀裂１４（亀裂１７）の進展が阻まれるため、生じた窒素ガスＧが仮想面１５の外部に逃げるのを抑制することができる。このような周縁領域１６は、その幅を３０μｍ以上とすることができる。なお、加熱以外の方法でＧａＮインゴット２０に何らかの力を作用させることにより、複数の亀裂１４を互いに繋げて亀裂１７を形成してもよい。また、仮想面１５に沿って複数の改質スポット１３を形成することにより、複数の亀裂１４を互いに繋げて亀裂１７を形成してもよい。 In the heating step, the peripheral region 16 prevents the plurality of cracks 14 (cracks 17) from propagating, and thus the generated nitrogen gas G can be suppressed from escaping to the outside of the virtual surface 15. Such a peripheral region 16 can have a width of 30 μm or more. The cracks 17 may be formed by connecting the plurality of cracks 14 to each other by applying some force to the GaN ingot 20 by a method other than heating. Further, by forming the plurality of modified spots 13 along the virtual surface 15, the plurality of cracks 14 may be connected to each other to form the crack 17.
　図９（ａ）～図９（ｄ）は、改質領域１２を形成したＧａＮインゴット２０を加熱した際における加工対象領域Ｒを示す写真図である。図９（ａ）の例では、加熱温度が４０℃であり、図９（ｂ）の例では、加熱温度が８５℃であり、図９（ｃ）の例では、加熱温度が１６５℃であり、図９（ｂ）の例では、加熱温度が３５０℃である。図９（ａ）～図９（ｃ）に示されるように、ＧａＮインゴット２０の温度上昇に伴い、仮想面１５に沿って窒素ガスＧが膨張し、亀裂１４が成長する。そして、図９（ｄ）に示されるように、周縁領域１６で窒素ガスＧの膨張が抑えられて封じられ、仮想面１５のほぼ全域に渡って拡大した亀裂１７が形成されることが確認できる。 FIGS. 9A to 9D are photographic diagrams showing the processing target region R when the GaN ingot 20 having the modified region 12 formed thereon is heated. In the example of FIG. 9A, the heating temperature is 40° C., in the example of FIG. 9B, the heating temperature is 85° C., and in the example of FIG. 9C, the heating temperature is 165° C. In the example of FIG. 9B, the heating temperature is 350° C. As shown in FIGS. 9A to 9C, as the temperature of the GaN ingot 20 rises, the nitrogen gas G expands along the virtual plane 15 and the crack 14 grows. Then, as shown in FIG. 9D, it can be confirmed that the expansion of the nitrogen gas G is suppressed and sealed in the peripheral region 16 and the expanded crack 17 is formed over almost the entire virtual surface 15. ..
　以上の結果、半導体インゴット（半導体対象物）として、次のＧａＮインゴット２０が得られる。図８に示されるように、ＧａＮインゴット２０は、内部において、表面２０ａに対向する仮想面１５に沿って形成された改質領域１２と、改質領域１２を囲うように設けられた周縁領域１６と、を備える。改質領域１２は、複数の改質スポット１３と複数の改質スポット１３からそれぞれ延びる複数の亀裂１４と窒素ガスＧとを含む。改質領域１２は、Ｚ方向に並ぶように複数設けられている。周縁領域１６は、改質スポット１３が形成されていない領域であって、囲う改質領域１２からＧａＮインゴット２０の外面への亀裂１４の進展を阻む。周縁領域１６は、複数の改質領域１２のそれぞれに対応して複数設けられている。周縁領域１６は、囲う改質領域１２から当該改質領域１２に隣接する他の改質領域１２への亀裂１４の進展を阻む。 As a result of the above, the following GaN ingot 20 is obtained as a semiconductor ingot (semiconductor object). As shown in FIG. 8, inside the GaN ingot 20, the modified region 12 formed along the virtual surface 15 facing the surface 20 a and the peripheral region 16 provided so as to surround the modified region 12. And The reforming region 12 includes a plurality of reforming spots 13, a plurality of cracks 14 extending from the plurality of reforming spots 13, and a nitrogen gas G, respectively. A plurality of modified regions 12 are provided so as to be aligned in the Z direction. The peripheral region 16 is a region where the modified spot 13 is not formed, and prevents the crack 14 from propagating from the surrounding modified region 12 to the outer surface of the GaN ingot 20. A plurality of peripheral regions 16 are provided corresponding to each of the plurality of modified regions 12. The peripheral region 16 prevents the crack 14 from propagating from the surrounding modified region 12 to another modified region 12 adjacent to the modified region 12.
　続いて、ＧａＮインゴット２０のうち複数の周縁領域１６を除去する周縁領域除去工程を実施する。周縁領域除去工程では、図１０に示されるように、レーザ加工装置１が、周縁領域１６と仮想面１５（加工対象領域Ｒ）との境界に設定された切断予定面Ｍに沿って、レーザ光Ｌ２をＧａＮインゴット２０の内部に集光させる。これにより、切断予定面Ｍに沿って、ＧａＮインゴット２０の内部に改質領域及び亀裂を形成する。このような改質領域及び亀裂の形成は、一般的な切断用のレーザ加工により実現できる。形成した改質領域及び亀裂に沿ってＧａＮインゴット２０を切断し、ＧａＮインゴット２０から複数の周縁領域１６を切り落とす。改質領域１２（析出したガリウムの析出面）を露出させる。 Subsequently, a peripheral region removing step of removing a plurality of peripheral regions 16 of the GaN ingot 20 is performed. In the peripheral area removing step, as shown in FIG. 10, the laser processing apparatus 1 causes the laser light to travel along the planned cutting plane M set at the boundary between the peripheral area 16 and the virtual surface 15 (processing target area R). L2 is focused inside the GaN ingot 20. As a result, a modified region and a crack are formed inside the GaN ingot 20 along the planned cutting surface M. The formation of such modified regions and cracks can be realized by general laser processing for cutting. The GaN ingot 20 is cut along the modified region and the crack thus formed, and the plurality of peripheral regions 16 are cut off from the GaN ingot 20. The modified region 12 (deposition surface of deposited gallium) is exposed.
　周縁領域除去工程では、周縁領域１６に対応する部分を、刃物（結晶カッター）等を用いて機械的に除去してもよい。周縁領域除去工程では、周縁領域１６に対応する部分を、ブレードダイシングにより除去してもよい。周縁領域除去工程では、周縁領域１６に対応する部分を、ダイヤモンドワイヤ等のワイヤーソーを用いて除去してもよい。周縁領域除去工程では、周縁領域１６に対応する部分を、砥石等の研磨材で研削（研磨）してもよい。 In the peripheral area removing step, the portion corresponding to the peripheral area 16 may be mechanically removed using a blade (crystal cutter) or the like. In the peripheral area removing step, the portion corresponding to the peripheral area 16 may be removed by blade dicing. In the peripheral area removing step, the portion corresponding to the peripheral area 16 may be removed using a wire saw such as a diamond wire. In the peripheral area removing step, the portion corresponding to the peripheral area 16 may be ground (polished) with an abrasive such as a grindstone.
　続いて、ＧａＮインゴット２０に形成された複数の改質領域１２に対して外部から刺激を付与する刺激付与工程を実施する。刺激付与工程では、図１１に示されるように、レーザ加工装置１がレーザ光Ｌ３を改質領域１２の内部に集光させ、改質領域１２に刺激を付与する。これにより、改質領域１２に含まれる窒素ガスＧの内圧解放効果も利用し、図１２（ａ）に示されるように、ＧａＮインゴット２０の一部を仮想面１５に沿って剥離する。ここでは、複数の改質領域１２の内部にレーザ光Ｌ３を同時に又は順次に集光させ、ＧａＮインゴット２０の各一部を仮想面１５に沿って同時に又は順次に剥離する。 Subsequently, a stimulus applying step of externally applying a stimulus to the plurality of modified regions 12 formed on the GaN ingot 20 is performed. In the stimulus applying step, as shown in FIG. 11, the laser processing apparatus 1 focuses the laser light L3 inside the modified region 12 and applies the stimulus to the modified region 12. As a result, the internal pressure releasing effect of the nitrogen gas G contained in the reformed region 12 is also used, and as shown in FIG. 12A, a part of the GaN ingot 20 is peeled off along the virtual surface 15. Here, the laser light L3 is simultaneously or sequentially focused inside the plurality of modified regions 12, and each part of the GaN ingot 20 is stripped simultaneously or sequentially along the virtual surface 15.
　刺激付与工程では、刃物等を用いて、改質領域１２に機械的に刺激を付与してもよい。刺激付与工程では、ブレードダイシングにより改質領域１２に刺激を付与してもよい。刺激付与工程では、ダイヤモンドワイヤ等のワイヤーソーを用いて、改質領域１２に刺激を付与してもよい。刺激付与工程では、ＧａＮインゴット２０における１つの外面（一方向）から刺激を付与してもよいし、複数の外面（多方向）から刺激を付与してもよい。刺激付与工程では、超音波振動等により非接触で改質領域１２に刺激を付与してもよい。刺激付与工程では、改質領域１２における少なくとも析出物及び亀裂１７に刺激を付与すればよい。 In the stimulating step, a stimulus may be used to mechanically apply stimulus to the modified region 12. In the stimulus applying step, stimulus may be applied to the modified region 12 by blade dicing. In the stimulating step, a stimulus may be applied to the modified region 12 using a wire saw such as a diamond wire. In the stimulus applying step, the stimulus may be applied from one outer surface (one direction) of the GaN ingot 20 or may be applied from a plurality of outer surfaces (multi-directions). In the stimulation applying step, stimulation may be applied to the modified region 12 in a non-contact manner by ultrasonic vibration or the like. In the stimulus applying step, stimulus may be applied to at least the precipitate and the crack 17 in the modified region 12.
　続いて、図１２（ｂ）に示されるように、剥離したＧａＮインゴット２０の各一部に対して、改質領域１２を除去してウェハ化するウェハ化工程を実施する。ウェハ化工程では、エッチング又は研磨により、剥離したＧａＮインゴット２０の各一部に残存する改質領域１２を除去する。ウェハ化工程では、その他の機械加工又はレーザ加工等によって、改質領域１２を除去してもよい。以上により、複数の改質領域１２を起点にＧａＮインゴット２０がスライスされる。すなわち、亀裂１７を利用して、ＧａＮインゴット２０が切断される。その結果、複数の亀裂１７のそれぞれを境界として、ＧａＮインゴット２０から複数のＧａＮウェハ３０が取得されることとなる。 Subsequently, as shown in FIG. 12B, a wafer forming process is performed on each part of the separated GaN ingot 20 by removing the modified region 12 to form a wafer. In the wafer forming process, the modified region 12 remaining on each part of the separated GaN ingot 20 is removed by etching or polishing. In the wafer forming process, the modified region 12 may be removed by other mechanical processing, laser processing, or the like. As described above, the GaN ingot 20 is sliced starting from the plurality of modified regions 12. That is, the GaN ingot 20 is cut using the crack 17. As a result, a plurality of GaN wafers 30 are obtained from the GaN ingot 20 with each of the plurality of cracks 17 as a boundary.
　以上の工程のうち、レーザ加工工程までが第１実施形態のレーザ加工方法である。以上の工程のうち、複数のＧａＮウェハ３０を取得する工程までが、第１実施形態の半導体部材製造方法である。周縁領域除去工程と刺激付与工程とウェハ化工程とが、第２工程を構成する。 Among the above steps, up to the laser processing step is the laser processing method of the first embodiment. Among the above steps, the steps up to the step of obtaining the plurality of GaN wafers 30 are the semiconductor member manufacturing method of the first embodiment. The peripheral region removing step, the stimulating step, and the wafer forming step constitute the second step.
　以上説明したように、第１実施形態のレーザ加工方法及び半導体部材製造方法では、改質領域１２からＧａＮインゴット２０の外面へ亀裂１４が進展することを周縁領域１６によって阻むことができる。改質領域１２に含まれる窒素ガスＧが亀裂１４を介して外部へ逃げてしまうことを抑制することができる。よって、窒素ガスＧの圧力（内圧）を効果的に上昇ないし維持させることが可能となる。その結果、当該内圧を利用し、仮想面１５に渡る亀裂１７を容易に形成することが可能となる。仮想面１５に渡る亀裂１７を境界としてＧａＮインゴット２０からＧａＮウェハ３０を取得することにより、好適なＧａＮウェハ３０の取得が可能となる。 As described above, in the laser processing method and the semiconductor member manufacturing method of the first embodiment, the peripheral region 16 can prevent the crack 14 from propagating from the modified region 12 to the outer surface of the GaN ingot 20. It is possible to prevent the nitrogen gas G contained in the reformed region 12 from escaping to the outside through the crack 14. Therefore, the pressure (internal pressure) of the nitrogen gas G can be effectively increased or maintained. As a result, it is possible to easily form the crack 17 across the virtual surface 15 using the internal pressure. By obtaining the GaN wafer 30 from the GaN ingot 20 with the crack 17 across the virtual plane 15 as the boundary, it is possible to obtain the suitable GaN wafer 30.
　また、第１実施形態のレーザ加工方法及び半導体部材製造方法では、仮想面１５に沿った亀裂１４の進展量が大きく、仮想面１５の大面積化が可能である。仮想面１５に沿った良好な切断（スライシング）を実現することが可能となる。凹凸の小さな剥離面（切断面）を得ることができる。例えば一般的なスライシングによる剥離面の凹凸は２５μｍ程度であるのに対して、第１実施形態による剥離面の凹凸は５μｍと極めて小さいものとなる。さらに、スライシングで敬遠されるＺ方向に延びる亀裂を抑制することが可能となる。 In addition, in the laser processing method and the semiconductor member manufacturing method of the first embodiment, the amount of progress of the crack 14 along the virtual surface 15 is large, and the area of the virtual surface 15 can be increased. Good cutting (slicing) along the virtual surface 15 can be realized. It is possible to obtain a peeled surface (cut surface) having small unevenness. For example, the unevenness of the peeling surface by general slicing is about 25 μm, while the unevenness of the peeling surface according to the first embodiment is as small as 5 μm. Furthermore, it is possible to suppress cracks extending in the Z direction, which is shunned by slicing.
　第１実施形態のレーザ加工方法及び半導体部材製造方法では、周縁領域１６は、Ｚ方向から見て改質領域１２を囲う枠状を呈している。このような周縁領域１６を形成することにより、ＧａＮインゴット２０の外面への亀裂１４の進展を効果的に阻むことができる。 In the laser processing method and semiconductor member manufacturing method of the first embodiment, the peripheral region 16 has a frame shape surrounding the modified region 12 when viewed from the Z direction. By forming such a peripheral region 16, it is possible to effectively prevent the crack 14 from propagating to the outer surface of the GaN ingot 20.
　第１実施形態のレーザ加工方法及び半導体部材製造方法では、半導体対象物としてＧａＮインゴット２０を用いている。窒化物を含むＧａＮインゴット２０を用いることで、ＧａＮインゴット２０の内部にレーザ光Ｌを入射させることにより、ＧａＮインゴット２０を分解し、窒素ガスＧを発生させることができる。なお、窒化ガリウムは光学デバイス又はパワーデバイスへの応用が進んでおり、この点においても、半導体対象物としてＧａＮインゴット２０を用いることは有効である。 In the laser processing method and the semiconductor member manufacturing method of the first embodiment, the GaN ingot 20 is used as the semiconductor object. By using the GaN ingot 20 containing a nitride, it is possible to decompose the GaN ingot 20 and generate the nitrogen gas G by making the laser light L enter the inside of the GaN ingot 20. Note that gallium nitride is being applied to optical devices or power devices, and in this respect also, it is effective to use the GaN ingot 20 as a semiconductor object.
　第１実施形態の半導体部材製造方法では、仮想面１５は、Ｚ方向に並ぶように複数設定されている。改質領域１２及び周縁領域１６は、複数の仮想面１５のそれぞれに対応して複数設けられている。周縁領域１６は、囲う改質領域１２から当該改質領域１２に隣接する他の改質領域１２への亀裂１４の進展を阻む。これによれば、１つのＧａＮインゴット２０から複数のＧａＮウェハ３０の取得が可能となる。また、周縁領域１６によって改質領域１２から他の改質領域１２への亀裂１４の進展が阻まれていることから、改質領域１２から他の改質領域１２へ窒素ガスＧが逃げてしまうことを抑制することができ、窒素ガスＧの圧力を効果的に上昇ないし維持させることが可能となる。 In the semiconductor member manufacturing method of the first embodiment, a plurality of virtual surfaces 15 are set so as to be lined up in the Z direction. A plurality of modified regions 12 and peripheral regions 16 are provided corresponding to each of the plurality of virtual surfaces 15. The peripheral region 16 prevents the crack 14 from propagating from the surrounding modified region 12 to another modified region 12 adjacent to the modified region 12. According to this, a plurality of GaN wafers 30 can be obtained from one GaN ingot 20. Further, since the peripheral region 16 prevents the crack 14 from propagating from the reforming region 12 to another reforming region 12, the nitrogen gas G escapes from the reforming region 12 to the other reforming region 12. This can be suppressed, and the pressure of the nitrogen gas G can be effectively increased or maintained.
　第１実施形態の半導体部材製造方法では、レーザ加工工程の後、ＧａＮインゴット２０を加熱し、窒素ガスＧを膨張させて、亀裂１４を仮想面１５に沿って進展させる。これにより、仮想面１５に渡る亀裂１４を確実に形成することができる。 In the semiconductor member manufacturing method according to the first embodiment, after the laser processing step, the GaN ingot 20 is heated and the nitrogen gas G is expanded to cause the crack 14 to propagate along the virtual surface 15. As a result, the crack 14 extending over the virtual surface 15 can be reliably formed.
　第１実施形態の半導体部材製造方法では、レーザ加工工程の後、改質領域１２に外部から刺激を付与することで、ＧａＮインゴット２０の一部を仮想面１５に沿って剥離する。これによれば、改質領域１２の窒素ガスＧの圧力を解放しつつ、この解放される力も利用してＧａＮインゴット２０の一部を剥離することができる。 In the semiconductor member manufacturing method according to the first embodiment, after the laser processing step, a stimulus is externally applied to the modified region 12 to peel off a part of the GaN ingot 20 along the virtual surface 15. According to this, while releasing the pressure of the nitrogen gas G in the reforming region 12, a part of the GaN ingot 20 can be peeled off by also utilizing this released force.
　第１実施形態のＧａＮインゴット２０では、改質領域１２からＧａＮインゴット２０の外面へ亀裂１４が進展することが周縁領域１６によって阻まれており、改質領域１２に含まれる窒素ガスＧが亀裂１４を介して外部へ逃げてしまうことが抑制されている。よって、窒素ガスＧの圧力を効果的に上昇ないし維持させることが可能となる。当該内圧を利用し、仮想面１５に沿って亀裂１４を精度よく進展させることが可能となる。仮想面１５に渡る亀裂１７を境界としてＧａＮインゴット２０からＧａＮウェハ３０を取得することにより、好適なＧａＮウェハ３０の取得が可能となる。 In the GaN ingot 20 of the first embodiment, the peripheral region 16 prevents the crack 14 from propagating from the reformed region 12 to the outer surface of the GaN ingot 20, and the nitrogen gas G contained in the reformed region 12 cracks 14. Escape to the outside through the is suppressed. Therefore, the pressure of the nitrogen gas G can be effectively increased or maintained. Using the internal pressure, the crack 14 can be accurately propagated along the virtual surface 15. By obtaining the GaN wafer 30 from the GaN ingot 20 with the crack 17 across the virtual plane 15 as the boundary, it is possible to obtain the suitable GaN wafer 30.
　第１実施形態のＧａＮインゴット２０では、改質領域１２は、Ｚ方向に並ぶように複数設けられている。周縁領域１６は、複数の改質領域１２のそれぞれに対応して複数設けられ、囲う改質領域１２から当該改質領域１２に隣接する他の改質領域１２への亀裂１４の進展を阻む。これによれば、１つのＧａＮインゴット２０から、複数のＧａＮウェハ３０を取得することが可能となる。改質領域１２から他の改質領域１２へ窒素ガスＧが逃げてしまうことを抑制することができ、窒素ガスＧの圧力を効果的に上昇ないし維持させることが可能となる。 In the GaN ingot 20 of the first embodiment, a plurality of modified regions 12 are provided so as to be lined up in the Z direction. A plurality of peripheral regions 16 are provided corresponding to each of the plurality of modified regions 12, and prevent the crack 14 from propagating from the surrounding modified region 12 to another modified region 12 adjacent to the modified region 12. According to this, it becomes possible to acquire a plurality of GaN wafers 30 from one GaN ingot 20. It is possible to prevent the nitrogen gas G from escaping from the reforming region 12 to another reforming region 12, and it is possible to effectively increase or maintain the pressure of the nitrogen gas G.
　なお、第１実施形態のレーザ加工方法及び半導体部材製造方法では、周縁領域１６は、窒化物の分解で析出し且つ溶融した析出物の外部への流出をも阻む。これにより、析出物を加工対象領域Ｒに留め、後段の加熱工程で加熱する際の起点として当該析出物を利用することができる。 In the laser processing method and the semiconductor member manufacturing method according to the first embodiment, the peripheral region 16 also blocks the outflow of the precipitate deposited by decomposition of the nitride and melted to the outside. Accordingly, the precipitate can be retained in the processing target region R, and the precipitate can be used as a starting point when heating in the subsequent heating step.
　図１３に示されるように、上述したレーザ加工方法及び半導体部材製造方法は、窒素ガスＧを外部へ逃がす孔Ｈ１，Ｈ２，Ｈ３を周縁領域１６に形成する孔形成工程をさらに備えていてもよい。孔形成工程は、加熱工程の前に実施される。孔Ｈ１，Ｈ２，Ｈ３は、改質領域１２に含まれるガスのガス抜き用の孔である。孔Ｈ１，Ｈ２，Ｈ３は、周縁領域１６の内外を連通させる。孔Ｈ１，Ｈ２，Ｈ３は、窒素ガスＧの圧力を一定以下までは低下させないように構成されている。 As shown in FIG. 13, the above-described laser processing method and semiconductor member manufacturing method may further include a hole forming step of forming holes H1, H2, and H3 that allow the nitrogen gas G to escape to the outside in the peripheral region 16. .. The hole forming step is performed before the heating step. The holes H1, H2, H3 are holes for venting the gas contained in the reforming region 12. The holes H1, H2, H3 communicate the inside and outside of the peripheral region 16. The holes H1, H2, H3 are configured so that the pressure of the nitrogen gas G does not drop below a certain level.
　孔Ｈ１は、改質領域１２（加工対象領域Ｒ）から側面２０ｂに達する第１の孔である。孔Ｈ２は、改質領域１２から側面２０ｂに達し、且つ孔Ｈ１よりも大径の第２の孔である。孔Ｈ３は、改質領域１２からＧａＮインゴット２０の角部に達する第３の孔である。孔Ｈ１，Ｈ２，Ｈ３は、上述したレーザ加工装置１により改質領域１２を形成する際に当該改質領域１２から延びる亀裂を利用して形成してもよい。この場合でも、周縁領域１６の上記機能は確保できる。孔Ｈ１，Ｈ２，Ｈ３の形成する手法は特に限定されず、公知の種々の手法を利用することができる。 The hole H1 is a first hole reaching the side surface 20b from the modified region 12 (processing target region R). The hole H2 is a second hole that reaches the side surface 20b from the modified region 12 and has a larger diameter than the hole H1. The hole H3 is a third hole reaching the corner of the GaN ingot 20 from the modified region 12. The holes H1, H2, H3 may be formed by utilizing a crack extending from the modified region 12 when the modified region 12 is formed by the laser processing device 1 described above. Even in this case, the function of the peripheral region 16 can be ensured. The method for forming the holes H1, H2, H3 is not particularly limited, and various known methods can be used.
　このような孔形成工程及びそれによる孔Ｈ１，Ｈ２，Ｈ３では、窒素ガスＧの圧力の上昇（膨張）で歪又は反りがＧａＮインゴット２０に加わる場合に、窒素ガスＧを外部へ逃がして当該歪又は反りを抑制することが可能となる。当該歪又は反りに起因したクラック及び転移の発生を抑制することができる。ＧａＮインゴット２０の一部が自然に剥離してしまうことを抑えることができる。例えばワックス等を貼り付けて剥離する際、その密着性を高めることができる。エッチングする場合、エッチャントが進入しやすくなり、エッチングレートを高めることができる。なお、孔Ｈ１，Ｈ２，Ｈ３のうち少なくとも何れかを形成してもよい。孔Ｈ１，Ｈ２，Ｈ３の数及び大きさは特に限定されず、ガリウムの析出量及び窒素ガスＧの内圧に応じて設定することができる。 In the hole forming step and the holes H1, H2, and H3 resulting therefrom, when the strain or warpage is applied to the GaN ingot 20 due to the increase (expansion) of the pressure of the nitrogen gas G, the nitrogen gas G is released to the outside to cause the strain. Alternatively, the warp can be suppressed. It is possible to suppress the occurrence of cracks and dislocations due to the strain or warpage. It is possible to prevent a part of the GaN ingot 20 from peeling off spontaneously. For example, when a wax or the like is attached and peeled off, the adhesion can be enhanced. In the case of etching, the etchant can easily enter, and the etching rate can be increased. At least one of the holes H1, H2, H3 may be formed. The number and size of the holes H1, H2, H3 are not particularly limited, and can be set according to the amount of gallium deposited and the internal pressure of the nitrogen gas G.
　上述した周縁領域除去工程では、複数の周縁領域１６を除去する加工を施す方向は限定されず、表面２０ａ側から加工してもよいし、側面２０ｂ側から加工してもよいし、表面２０ｃ側から加工してもよい。例えば図１４に示されるように、周縁領域除去工程では、周縁領域１６に対応する部分を、砥石等の研磨材ＰＬを側面２０ｂ側から改質領域１２の延びる方向に沿って接近させて研磨してもよい。 In the peripheral area removing step described above, the direction of processing for removing the plurality of peripheral areas 16 is not limited, and processing may be performed from the surface 20a side, the side surface 20b side, or the surface 20c side. It may be processed from. For example, as shown in FIG. 14, in the peripheral edge region removing step, a portion corresponding to the peripheral edge region 16 is polished by bringing an abrasive material PL such as a grindstone close to the side surface 20b along the extending direction of the modified region 12. May be.
　仮想面１５に沿った改質領域１２（複数の改質スポット１３）の形成については、特に限定されず、以下のように形成してもよい。 The formation of the modified region 12 (the plurality of modified spots 13) along the virtual surface 15 is not particularly limited, and may be formed as follows.
　まず、レーザ加工装置１が、図１５及び図１６に示されるように、表面２０ａからＧａＮインゴット２０の内部にレーザ光Ｌを入射させることにより、仮想面１５に沿って（例えば、仮想面１５の全体に沿って２次元に並ぶように）複数の改質スポット（第１改質スポット）１３ａを形成する。このとき、レーザ加工装置１は、複数の改質スポット１３ａからそれぞれ延びる複数の亀裂１４ａが互いに繋がらないように、複数の改質スポット１３ａを形成する。また、レーザ加工装置１は、パルス発振されたレーザ光Ｌの集光点Ｃを仮想面１５に沿って移動させることにより、複数列の改質スポット１３ａを形成する。なお、図１５及び図１６では、改質スポット１３ａが白抜き（ハッチングなし）で示されており、亀裂１４ａが延びる範囲が破線で示されている（図１７～図２２でも同様）。 First, as shown in FIGS. 15 and 16, the laser processing apparatus 1 causes the laser light L to enter the inside of the GaN ingot 20 from the front surface 20 a, so that the laser light L is incident along the virtual surface 15 (for example, in the virtual surface 15). A plurality of modified spots (first modified spots) 13a are formed so as to be arranged two-dimensionally along the whole. At this time, the laser processing apparatus 1 forms the plurality of modified spots 13a so that the plurality of cracks 14a extending from the plurality of modified spots 13a are not connected to each other. Further, the laser processing apparatus 1 forms the modified spots 13a in a plurality of rows by moving the condensing point C of the pulsed laser light L along the virtual surface 15. In FIGS. 15 and 16, the modified spot 13a is shown in white (without hatching), and the range in which the crack 14a extends is shown by a broken line (the same applies to FIGS. 17 to 22).
　変形例では、パルス発振されたレーザ光Ｌが、Ｙ方向に並ぶ複数（例えば６つ）の集光点Ｃに集光されるように、空間光変調器４によって変調される。そして、複数の集光点Ｃが、Ｘ方向に沿って仮想面１５上を相対的に移動させられる。一例として、Ｙ方向において隣り合う集光点Ｃ間の距離は８μｍであり、レーザ光Ｌのパルスピッチ（すなわち、複数の集光点Ｃの相対的な移動速度を、レーザ光Ｌの繰り返し周波数で除した値）は１０μｍである。また、１つの集光点Ｃ当たりのレーザ光Ｌのパルスエネルギー（以下、単に「レーザ光Ｌのパルスエネルギー」という）は、０．３３μＪである。この場合、Ｙ方向において隣り合う改質スポット１３ａの中心間距離は８μｍとなり、Ｘ方向において隣り合う改質スポット１３ａの中心間距離は１０μｍとなる。また、複数の改質スポット１３ａからそれぞれ延びる複数の亀裂１４ａは互いに繋がらない。 In a modified example, the pulsed laser light L is modulated by the spatial light modulator 4 so as to be condensed at a plurality of (for example, six) condensing points C arranged in the Y direction. Then, the plurality of condensing points C are relatively moved on the virtual surface 15 along the X direction. As an example, the distance between the condensing points C adjacent to each other in the Y direction is 8 μm, and the pulse pitch of the laser light L (that is, the relative moving speed of the plurality of condensing points C is determined by the repetition frequency of the laser light L). The divided value) is 10 μm. The pulse energy of the laser light L per one condensing point C (hereinafter, simply referred to as “pulse energy of the laser light L”) is 0.33 μJ. In this case, the center-to-center distance between adjacent modified spots 13a in the Y direction is 8 μm, and the center-to-center distance between adjacent modified spots 13a in the X direction is 10 μm. Further, the cracks 14a extending from the modified spots 13a are not connected to each other.
　続いて、レーザ加工装置１が、図１７及び図１８に示されるように、表面２０ａからＧａＮインゴット２０の内部にレーザ光Ｌを入射させることにより、仮想面１５に沿って（例えば、仮想面１５の全体に沿って２次元に並ぶように）複数の改質スポット（第２改質スポット）１３ｂを形成する。このとき、レーザ加工装置１は、複数の改質スポット１３ａ及び複数の亀裂１４ａに重ならないように、複数の改質スポット１３ｂを形成する。また、レーザ加工装置１は、パルス発振されたレーザ光Ｌの集光点Ｃを複数列の改質スポット１３ａの列間において仮想面１５に沿って移動させることにより、複数列の改質スポット１３ｂを形成する。この工程では、複数の改質スポット１３ｂからそれぞれ延びる複数の亀裂１４ｂが、複数の亀裂１４ａに繋がってもよい。なお、図１７及び図１８では、改質スポット１３ｂがドットハッチングで示されており、亀裂１４ｂが延びる範囲が破線で示されている（図１９～図２２でも同様）。 Then, the laser processing apparatus 1 causes the laser light L to enter the inside of the GaN ingot 20 from the surface 20a as shown in FIGS. A plurality of modified spots (second modified spots) 13b are formed so as to be arranged two-dimensionally along the entire area. At this time, the laser processing apparatus 1 forms the plurality of modified spots 13b so as not to overlap the plurality of modified spots 13a and the plurality of cracks 14a. Moreover, the laser processing apparatus 1 moves the condensing point C of the pulsed laser light L along the virtual plane 15 between the rows of the reforming spots 13a of the plurality of rows to thereby form the reforming spots 13b of the plurality of rows. To form. In this step, the cracks 14b extending from the modified spots 13b may be connected to the cracks 14a. 17 and 18, the modified spot 13b is indicated by dot hatching, and the range in which the crack 14b extends is indicated by broken lines (the same applies to FIGS. 19 to 22).
　変形例では、パルス発振されたレーザ光Ｌが、Ｙ方向に並ぶ複数（例えば６つ）の集光点Ｃに集光されるように、空間光変調器４によって変調される。そして、複数の集光点Ｃが、複数列の改質スポット１３ａの列間の中心において、Ｘ方向に沿って仮想面１５上を相対的に移動させられる。一例として、Ｙ方向において隣り合う集光点Ｃ間の距離は８μｍであり、レーザ光Ｌのパルスピッチは１０μｍである。また、レーザ光Ｌのパルスエネルギーは、０．３３μＪである。この場合、Ｙ方向において隣り合う改質スポット１３ｂの中心間距離は８μｍとなり、Ｘ方向において隣り合う改質スポット１３ｂの中心間距離は１０μｍとなる。 In a modified example, the pulsed laser light L is modulated by the spatial light modulator 4 so as to be condensed at a plurality of (for example, six) condensing points C arranged in the Y direction. Then, the plurality of condensing points C are relatively moved on the virtual surface 15 along the X direction at the centers between the rows of the reformed spots 13a. As an example, the distance between the condensing points C adjacent to each other in the Y direction is 8 μm, and the pulse pitch of the laser light L is 10 μm. The pulse energy of the laser light L is 0.33 μJ. In this case, the center-to-center distance between adjacent modified spots 13b in the Y direction is 8 μm, and the center-to-center distance between adjacent modified spots 13b in the X direction is 10 μm.
　続いて、レーザ加工装置１が、図１９及び図２０に示されるように、表面２０ａからＧａＮインゴット２０の内部にレーザ光Ｌを入射させることにより、仮想面１５に沿って（例えば、仮想面１５の全体に沿って２次元に並ぶように）複数の改質スポット（第３改質スポット）１３ｃを形成する。更に、レーザ加工装置１が、図２１及び図２２に示されるように、表面２０ａからＧａＮインゴット２０の内部にレーザ光Ｌを入射させることにより、仮想面１５に沿って（例えば、仮想面１５の全体に沿って２次元に並ぶように）複数の改質スポット（第３改質スポット）１３ｄを形成する。このとき、レーザ加工装置１は、複数の改質スポット１３ａ，１３ｂに重ならないように、複数の改質スポット１３ｃ，１３ｄを形成する。また、レーザ加工装置１は、パルス発振されたレーザ光Ｌの集光点Ｃを複数列の改質スポット１３ａ，１３ｂの列間において仮想面１５に沿って移動させることにより、複数列の改質スポット１３ｃ，１３ｄを形成する。この工程では、複数の改質スポット１３ｃ，１３ｄからそれぞれ延びる複数の亀裂１４ｃ，１４ｄが、複数の亀裂１４ａ，１４ｂに繋がってもよい。なお、図１９及び図２０では、改質スポット１３ｃが実線ハッチングで示されており、亀裂１４ｃが延びる範囲が破線で示されている（図２１及び図２２でも同様）。また、図２１及び図２２では、改質スポット１３ｄが実線ハッチング（改質スポット１３ｃの実線ハッチングとは逆に傾斜する実線ハッチング）で示されており、亀裂１４ｄが延びる範囲が破線で示されている。 Next, as shown in FIGS. 19 and 20, the laser processing device 1 causes the laser light L to enter the inside of the GaN ingot 20 from the surface 20 a, so that the laser light L is guided along the virtual surface 15 (for example, the virtual surface 15). A plurality of modified spots (third modified spots) 13c are formed so as to be arranged two-dimensionally along the entire area. Further, as shown in FIGS. 21 and 22, the laser processing apparatus 1 causes the laser light L to enter the inside of the GaN ingot 20 from the surface 20 a, so that the laser light L is guided along the virtual surface 15 (for example, the virtual surface 15 A plurality of modified spots (third modified spots) 13d are formed so as to be arranged two-dimensionally along the whole. At this time, the laser processing apparatus 1 forms the plurality of modified spots 13c and 13d so as not to overlap the plurality of modified spots 13a and 13b. Further, the laser processing apparatus 1 moves the condensing point C of the pulsed laser light L along the virtual plane 15 between the rows of the reforming spots 13a and 13b of the plurality of rows, thereby reforming the plurality of rows. The spots 13c and 13d are formed. In this step, the cracks 14c and 14d extending from the modified spots 13c and 13d may be connected to the cracks 14a and 14b. 19 and 20, the modified spot 13c is shown by solid line hatching, and the range in which the crack 14c extends is shown by broken lines (also in FIGS. 21 and 22). 21 and 22, the modified spot 13d is shown by solid line hatching (solid line hatching that is the reverse of the solid line hatching of the modified spot 13c), and the range in which the crack 14d extends is shown by broken lines. There is.
　変形例では、パルス発振されたレーザ光Ｌが、Ｙ方向に並ぶ複数（例えば６つ）の集光点Ｃに集光されるように、空間光変調器４によって変調される。そして、複数の集光点Ｃが、複数列の改質スポット１３ａ，１３ｂの列間の中心において、Ｘ方向に沿って仮想面１５上を相対的に移動させられる。一例として、Ｙ方向において隣り合う集光点Ｃ間の距離は８μｍであり、レーザ光Ｌのパルスピッチは５μｍである。また、レーザ光Ｌのパルスエネルギーは、０．３３μＪである。この場合、Ｙ方向において隣り合う改質スポット１３ｃの中心間距離は８μｍとなり、Ｘ方向において隣り合う改質スポット１３ｃの中心間距離は５μｍとなる。また、Ｙ方向において隣り合う改質スポット１３ｄの中心間距離は８μｍとなり、Ｘ方向において隣り合う改質スポット１３ｄの中心間距離は５μｍとなる。 In a modified example, the pulsed laser light L is modulated by the spatial light modulator 4 so as to be condensed at a plurality of (for example, six) condensing points C arranged in the Y direction. Then, the plurality of converging points C are relatively moved on the virtual surface 15 along the X direction at the center between the rows of the reformed spots 13a and 13b of the plurality of rows. As an example, the distance between the condensing points C adjacent to each other in the Y direction is 8 μm, and the pulse pitch of the laser light L is 5 μm. The pulse energy of the laser light L is 0.33 μJ. In this case, the center-to-center distance between adjacent modified spots 13c in the Y direction is 8 μm, and the center-to-center distance between adjacent modified spots 13c in the X direction is 5 μm. Further, the center-to-center distance between the modified spots 13d adjacent to each other in the Y direction is 8 μm, and the center-to-center distance between the modified spots 13d adjacent to each other in the X-direction is 5 μm.
　ここで、変形例に係るレーザ加工方法及び半導体部材製造方法によって形成されたＧａＮウェハ３０では、ＧａＮウェハ３０の剥離面に現れる凹凸が小さくなることを示す実験結果について説明する。 Here, an explanation will be given of an experimental result showing that in the GaN wafer 30 formed by the laser processing method and the semiconductor member manufacturing method according to the modified example, the unevenness appearing on the separated surface of the GaN wafer 30 becomes small.
　図２３は、一例のレーザ加工方法及び半導体部材製造方法によって形成されたＧａＮウェハの剥離面の画像であり、図２４の（ａ）及び（ｂ）は、図２３に示される剥離面の高さプロファイルである。この例では、５３２ｎｍの波長を有するレーザ光ＬをＧａＮインゴット２０の表面２０ａからＧａＮインゴット２０の内部に入射させ、１つの集光点Ｃを、Ｘ方向に沿って仮想面１５上を相対的に移動させることにより、仮想面１５に沿って複数の改質スポット１３を形成した。このとき、Ｙ方向において隣り合う集光点Ｃ間の距離を１０μｍ、レーザ光Ｌのパルスピッチを１μｍ、レーザ光Ｌのパルスエネルギーを１μＪとした。この場合、図２４の（ａ）及び（ｂ）に示されるように、ＧａＮウェハ３０の剥離面（亀裂１７によって形成された面）に２５μｍ程度の凹凸が現れた。 FIG. 23 is an image of a peeled surface of a GaN wafer formed by the laser processing method and the semiconductor member manufacturing method of an example, and FIGS. 24A and 24B show the height of the peeled surface shown in FIG. It is a profile. In this example, laser light L having a wavelength of 532 nm is made incident on the inside of the GaN ingot 20 from the surface 20a of the GaN ingot 20, and one condensing point C is relatively moved on the virtual plane 15 along the X direction. By moving, a plurality of modified spots 13 were formed along the virtual surface 15. At this time, the distance between adjacent condensing points C in the Y direction was 10 μm, the pulse pitch of the laser light L was 1 μm, and the pulse energy of the laser light L was 1 μJ. In this case, as shown in (a) and (b) of FIG. 24, irregularities of about 25 μm appeared on the separation surface (surface formed by the crack 17) of the GaN wafer 30.
　図２５は、他の例のレーザ加工方法及び半導体部材製造方法によって形成されたＧａＮウェハの剥離面の画像であり、図２６の（ａ）及び（ｂ）は、図２５に示される剥離面の高さプロファイルである。この例では、５３２ｎｍの波長を有するレーザ光ＬをＧａＮインゴット２０の表面２０ａからＧａＮインゴット２０の内部に入射させ、変形例のレーザ加工方法及び半導体部材製造方法と同様に、仮想面１５に沿って複数の改質スポット１３を形成した。複数の改質スポット１３ａを形成する際には、Ｙ方向において隣り合う集光点Ｃ間の距離を６μｍ、レーザ光Ｌのパルスピッチを１０μｍ、レーザ光Ｌのパルスエネルギーを０．３３μＪとした。複数の改質スポット１３ｂを形成する際には、Ｙ方向において隣り合う集光点Ｃ間の距離を６μｍ、レーザ光Ｌのパルスピッチを１０μｍ、レーザ光Ｌのパルスエネルギーを０．３３μＪとした。複数の改質スポット１３ｃを形成する際には、Ｙ方向において隣り合う集光点Ｃ間の距離を６μｍ、レーザ光Ｌのパルスピッチを５μｍ、レーザ光Ｌのパルスエネルギーを０．３３μＪとした。複数の改質スポット１３ｄを形成する際には、Ｙ方向において隣り合う集光点Ｃ間の距離を６μｍ、レーザ光Ｌのパルスピッチを５μｍ、レーザ光Ｌのパルスエネルギーを０．３３μＪとした。この場合、図２６の（ａ）及び（ｂ）に示されるように、ＧａＮウェハ３０の剥離面に５μｍ程度の凹凸が現れた。 FIG. 25 is an image of a peeled surface of a GaN wafer formed by another example of the laser processing method and the semiconductor member manufacturing method, and FIGS. 26A and 26B are images of the peeled surface shown in FIG. It is a height profile. In this example, laser light L having a wavelength of 532 nm is made to enter the inside of the GaN ingot 20 from the surface 20a of the GaN ingot 20, and along the virtual plane 15 as in the modified laser processing method and semiconductor member manufacturing method. A plurality of modified spots 13 were formed. When forming the plurality of modified spots 13a, the distance between the condensing points C adjacent to each other in the Y direction was 6 μm, the pulse pitch of the laser light L was 10 μm, and the pulse energy of the laser light L was 0.33 μJ. When forming the plurality of modified spots 13b, the distance between the condensing points C adjacent to each other in the Y direction was 6 μm, the pulse pitch of the laser light L was 10 μm, and the pulse energy of the laser light L was 0.33 μJ. When forming the plurality of modified spots 13c, the distance between the condensing points C adjacent to each other in the Y direction was 6 μm, the pulse pitch of the laser light L was 5 μm, and the pulse energy of the laser light L was 0.33 μJ. When forming the plurality of modified spots 13d, the distance between the condensing points C adjacent to each other in the Y direction was 6 μm, the pulse pitch of the laser light L was 5 μm, and the pulse energy of the laser light L was 0.33 μJ. In this case, as shown in FIGS. 26A and 26B, unevenness of about 5 μm appeared on the separated surface of the GaN wafer 30.
　以上の実験結果から、変形例のレーザ加工方法及び半導体部材製造方法によって形成されたＧａＮウェハでは、ＧａＮウェハ３０の剥離面に現れる凹凸が小さくなること、すなわち、仮想面１５に沿って亀裂１７が精度良く形成されることが分かった。なお、ＧａＮウェハ３０の剥離面に現れる凹凸が小さくなると、当該剥離面を平坦化するための研削量が少なくて済む。したがって、ＧａＮウェハ３０の剥離面に現れる凹凸が小さくなることは、材料の利用効率的にも生産効率的にも有利である。 From the above experimental results, in the GaN wafer formed by the laser processing method and the semiconductor member manufacturing method of the modified example, the irregularities appearing on the separated surface of the GaN wafer 30 are small, that is, the cracks 17 are formed along the virtual surface 15. It was found that it was formed accurately. It should be noted that if the irregularities appearing on the peeled surface of the GaN wafer 30 become small, the amount of grinding for flattening the peeled surface will be small. Therefore, it is advantageous in terms of material utilization efficiency and production efficiency that the irregularities appearing on the separated surface of the GaN wafer 30 become small.
　次に、ＧａＮウェハ３０の剥離面に凹凸が現れる原理について説明する。 Next, the principle that unevenness appears on the peeled surface of the GaN wafer 30 will be described.
　例えば、図２７に示されるように、仮想面１５に沿って複数の改質スポット１３ａを形成し、改質スポット１３ｂがその一方の側の改質スポット１３ａから延びる亀裂１４ａに重なるように、仮想面１５に沿って複数の改質スポット１３ｂを形成する。この場合には、複数の亀裂１４ａに析出したガリウムによってレーザ光Ｌが吸収され易い状態にあるため、集光点Ｃが仮想面１５上に位置していても、改質スポット１３ａに対してレーザ光Ｌの入射側に改質スポット１３ｂが形成され易くなる。続いて、改質スポット１３ｃがその一方の側の改質スポット１３ｂから延びる亀裂１４ｂに重なるように、仮想面１５に沿って複数の改質スポット１３ｃを形成する。この場合にも、複数の亀裂１４ｂに析出したガリウムによってレーザ光Ｌが吸収され易い状態にあるため、集光点Ｃが仮想面１５上に位置していても、改質スポット１３ｂに対してレーザ光Ｌの入射側に改質スポット１３ｃが形成され易くなる。このように、この例では、複数の改質スポット１３ｂが複数の改質スポット１３ａに対してレーザ光Ｌの入射側に形成され、更に、複数の改質スポット１３ｃが複数の改質スポット１３ｂに対してレーザ光Ｌの入射側に形成され易くなる。 For example, as shown in FIG. 27, a plurality of modified spots 13a are formed along the imaginary plane 15, and the modified spots 13b are virtual so that the modified spots 13b overlap the cracks 14a extending from the modified spots 13a on one side. A plurality of modified spots 13b are formed along the surface 15. In this case, since the laser light L is easily absorbed by the gallium deposited in the plurality of cracks 14a, even if the condensing point C is located on the virtual surface 15, the laser is not applied to the modified spot 13a. The modified spot 13b is easily formed on the incident side of the light L. Then, a plurality of modified spots 13c are formed along the virtual surface 15 so that the modified spots 13c overlap the cracks 14b extending from the modified spots 13b on one side. Also in this case, since the laser light L is easily absorbed by the gallium deposited in the plurality of cracks 14b, even if the condensing point C is located on the virtual surface 15, the laser is not applied to the modified spot 13b. The modified spot 13c is easily formed on the incident side of the light L. As described above, in this example, the plurality of modified spots 13b are formed on the incident side of the laser light L with respect to the plurality of modified spots 13a, and further, the plurality of modified spots 13c are formed into the plurality of modified spots 13b. On the other hand, it tends to be formed on the incident side of the laser light L.
　それに対し、例えば、図２８に示されるように、仮想面１５に沿って複数の改質スポット１３ａを形成し、改質スポット１３ｂがその両側の改質スポット１３ａから延びる亀裂１４ａに重ならないように、仮想面１５に沿って複数の改質スポット１３ｂを形成する。この場合には、複数の亀裂１４ａに析出したガリウムによってレーザ光Ｌが吸収され易い状態にあるものの、改質スポット１３ｂが亀裂１４ａに重ならないため、改質スポット１３ｂも、改質スポット１３ａと同様に仮想面１５上に形成される。続いて、改質スポット１３ｃがその両側の改質スポット１３ａ，１３ｂのそれぞれから延びる亀裂１４ａ，１４ｂに重なるように、仮想面１５に沿って複数の改質スポット１３ｃを形成する。更に、改質スポット１３ｄがその両側の改質スポット１３ａ，１３ｂのそれぞれから延びる亀裂１４ａ，１４ｂに重なるように、仮想面１５に沿って複数の改質スポット１３ｄを形成する。これらの場合には、複数の亀裂１４ａ，１４ｂに析出したガリウムによってレーザ光Ｌが吸収され易い状態にあるため、集光点Ｃが仮想面１５上に位置していても、改質スポット１３ａ，１３ｂに対してレーザ光Ｌの入射側に改質スポット１３ｃ，１３ｄが形成され易くなる。このように、この例では、複数の改質スポット１３ｃ，１３ｄが複数の改質スポット１３ａ，１３ｂに対してレーザ光Ｌの入射側に形成され易くなるだけである。 On the other hand, for example, as shown in FIG. 28, a plurality of modified spots 13a are formed along the virtual surface 15 so that the modified spots 13b do not overlap the cracks 14a extending from the modified spots 13a on both sides thereof. , A plurality of modified spots 13b are formed along the virtual surface 15. In this case, although the laser light L is easily absorbed by the gallium deposited in the plurality of cracks 14a, the modified spot 13b does not overlap the crack 14a, so the modified spot 13b is similar to the modified spot 13a. Are formed on the virtual surface 15. Subsequently, a plurality of modified spots 13c are formed along the virtual surface 15 so that the modified spots 13c overlap the cracks 14a and 14b extending from the modified spots 13a and 13b on both sides thereof. Further, a plurality of modified spots 13d are formed along the virtual surface 15 so that the modified spots 13d overlap the cracks 14a and 14b extending from the modified spots 13a and 13b on both sides thereof. In these cases, since the laser light L is easily absorbed by the gallium deposited on the plurality of cracks 14a and 14b, even if the condensing point C is located on the virtual surface 15, the modified spots 13a, The modified spots 13c and 13d are easily formed on the incident side of the laser light L with respect to 13b. As described above, in this example, the modified spots 13c and 13d are easily formed on the incident side of the laser light L with respect to the modified spots 13a and 13b.
　以上の原理から、変形例のレーザ加工方法及び半導体部材製造方法においては、複数の改質スポット１３ａ及び複数の改質スポット１３ａからそれぞれ延びる複数の亀裂１４ａに重ならないように、複数の改質スポット１３ｂを形成することが、ＧａＮウェハ３０の剥離面に現れる凹凸を小さくする上で極めて重要であることが分かる。 Based on the above principle, in the laser processing method and the semiconductor member manufacturing method of the modified example, the plurality of modified spots 13a and the plurality of modified spots 13a are formed so as not to overlap with the plurality of cracks 14a extending from the plurality of modified spots 13a. It can be seen that the formation of 13b is extremely important for reducing the unevenness appearing on the separated surface of the GaN wafer 30.
　次に、変形例のレーザ加工方法及び半導体部材製造方法においては、仮想面１５に沿って亀裂１７が精度良く進展することを示す実験結果について説明する。 Next, in the laser processing method and the semiconductor member manufacturing method of the modified example, an experimental result showing that the crack 17 propagates along the virtual surface 15 with high accuracy will be described.
　図２９の（ａ）及び（ｂ）は、一例のレーザ加工方法及び半導体部材製造方法の途中で形成された亀裂の画像であり、図２９の（ｂ）は、図２９の（ａ）における矩形枠内の拡大画像である。この例では、５３２ｎｍの波長を有するレーザ光ＬをＧａＮインゴット２０の表面２０ａからＧａＮインゴット２０の内部に入射させ、Ｙ方向に並ぶ６つの集光点Ｃを、Ｘ方向に沿って仮想面１５上を相対的に移動させることにより、仮想面１５に沿って複数の改質スポット１３を形成した。このとき、Ｙ方向において隣り合う集光点Ｃ間の距離を６μｍ、レーザ光Ｌのパルスピッチを１μｍ、レーザ光Ｌのパルスエネルギーを１．３３μＪとした。そして、レーザ加工を仮想面１５の途中で停止させた。この場合、図２９の（ａ）及び（ｂ）に示されるように、加工領域から未加工領域に進展した亀裂が、未加工領域において仮想面１５から大きく外れた。 29A and 29B are images of cracks formed during the example of the laser processing method and the semiconductor member manufacturing method, and FIG. 29B is a rectangle in FIG. 29A. It is an enlarged image in the frame. In this example, laser light L having a wavelength of 532 nm is made incident on the inside of the GaN ingot 20 from the surface 20a of the GaN ingot 20, and the six condensing points C arranged in the Y direction are arranged on the virtual surface 15 along the X direction. Were relatively moved to form a plurality of modified spots 13 along the virtual surface 15. At this time, the distance between the condensing points C adjacent to each other in the Y direction was 6 μm, the pulse pitch of the laser light L was 1 μm, and the pulse energy of the laser light L was 1.33 μJ. Then, the laser processing was stopped in the middle of the virtual surface 15. In this case, as shown in (a) and (b) of FIG. 29, the crack that propagated from the processed region to the unprocessed region largely deviated from the virtual surface 15 in the unprocessed region.
　図３０の（ａ）及び（ｂ）は、他の例のレーザ加工方法及び半導体部材製造方法の途中で形成された亀裂の画像であり、図３０の（ｂ）は、図３０の（ａ）における矩形枠内の拡大画像である。この例では、５３２ｎｍの波長を有するレーザ光ＬをＧａＮインゴット２０の表面２０ａからＧａＮインゴット２０の内部に入射させ、Ｙ方向に並ぶ６つの集光点Ｃを、Ｘ方向に沿って仮想面１５上を相対的に移動させることにより、仮想面１５に沿って複数の改質スポット１３を形成した。具体的には、まず、Ｙ方向において隣り合う集光点Ｃ間の距離を６μｍ、レーザ光Ｌのパルスピッチを１０μｍ、レーザ光Ｌのパルスエネルギーを０．３３μＪとして、加工領域１及び加工領域２に複数列の改質スポット１３を形成した。続いて、Ｙ方向において隣り合う集光点Ｃ間の距離を６μｍ、レーザ光Ｌのパルスピッチを１０μｍ、レーザ光Ｌのパルスエネルギーを０．３３μＪとして、加工領域１及び加工領域２に、既に形成された複数列の改質スポット１３の列間の中心にそれぞれの列が位置するように複数列の改質スポット１３を形成した。続いて、Ｙ方向において隣り合う集光点Ｃ間の距離を６μｍ、レーザ光Ｌのパルスピッチを５μｍ、レーザ光Ｌのパルスエネルギーを０．３３μＪとして、加工領域１のみに、既に形成された複数列の改質スポット１３の列間の中心にそれぞれの列が位置するように複数列の改質スポット１３を形成した。この場合、図３０の（ａ）及び（ｂ）に示されるように、加工領域１から加工領域２に進展した亀裂が、加工領域２において仮想面１５から大きく外れなかった。 30A and 30B are images of cracks formed during the laser processing method and the semiconductor member manufacturing method of another example, and FIG. 30B is the image of FIG. It is an enlarged image in the rectangular frame in. In this example, laser light L having a wavelength of 532 nm is made to enter the inside of the GaN ingot 20 from the surface 20a of the GaN ingot 20, and the six condensing points C arranged in the Y direction are arranged on the virtual surface 15 along the X direction. Were relatively moved to form a plurality of modified spots 13 along the virtual surface 15. Specifically, first, the processing area 1 and the processing area 2 are set such that the distance between the condensing points C adjacent to each other in the Y direction is 6 μm, the pulse pitch of the laser light L is 10 μm, and the pulse energy of the laser light L is 0.33 μJ. A plurality of rows of modified spots 13 were formed on the surface. Then, the distance between the condensing points C adjacent to each other in the Y direction is 6 μm, the pulse pitch of the laser light L is 10 μm, and the pulse energy of the laser light L is 0.33 μJ. A plurality of rows of modified spots 13 were formed such that each row was positioned in the center between the plurality of rows of modified spots 13. Then, the distance between the condensing points C adjacent to each other in the Y direction is 6 μm, the pulse pitch of the laser light L is 5 μm, and the pulse energy of the laser light L is 0.33 μJ. A plurality of rows of reforming spots 13 were formed such that each row was positioned at the center between the rows of reforming spots 13. In this case, as shown in (a) and (b) of FIG. 30, the crack that propagated from the processing region 1 to the processing region 2 did not largely deviate from the virtual surface 15 in the processing region 2.
　以上の実験結果から、変形例のレーザ加工方法及び半導体部材製造方法においては、仮想面１５に沿って亀裂１７が精度良く進展することが分かった。これは、加工領域２に先に形成された複数の改質スポット１３が、亀裂が進展する際にガイドになったためと想定される。 From the above experimental results, it was found that in the modified laser processing method and semiconductor member manufacturing method, the crack 17 propagates accurately along the virtual surface 15. It is assumed that this is because the plurality of modified spots 13 previously formed in the processed region 2 served as guides when the crack propagated.
　次に、変形例のレーザ加工方法及び半導体部材製造方法においては、改質スポット１３からレーザ光Ｌの入射側及びその反対側に延びる亀裂１４の延び量が抑制されることを示す実験結果について説明する。 Next, in the laser processing method and the semiconductor member manufacturing method of the modified example, the experimental result showing that the extension amount of the crack 14 extending from the modified spot 13 to the incident side of the laser light L and the opposite side thereof is suppressed will be described. To do.
　図３１は、比較例のレーザ加工方法及び半導体部材製造方法によって形成された改質スポット及び亀裂の画像（側面視での画像）である。この比較例では、５３２ｎｍの波長を有するレーザ光ＬをＧａＮインゴット２０の表面２０ａからＧａＮインゴット２０の内部に入射させ、１つの集光点Ｃを、Ｘ方向に沿って仮想面１５上を相対的に移動させることにより、仮想面１５に沿って複数の改質スポット１３を形成した。具体的には、Ｙ方向において隣り合う集光点Ｃ間の距離を２μｍ、レーザ光Ｌのパルスピッチを５μｍ、レーザ光Ｌのパルスエネルギーを０．３μＪとして、仮想面１５に沿って複数の改質スポット１３を形成した。この場合、図２２に示されるように、改質スポット１３からレーザ光Ｌの入射側及びその反対側に延びる亀裂１４の延び量が１００μｍ程度となった。 FIG. 31 is an image (a side view image) of modified spots and cracks formed by the laser processing method and the semiconductor member manufacturing method of the comparative example. In this comparative example, a laser beam L having a wavelength of 532 nm is made incident on the inside of the GaN ingot 20 from the surface 20a of the GaN ingot 20, and one condensing point C is relatively moved on the virtual plane 15 along the X direction. The plurality of modified spots 13 were formed along the imaginary plane 15 by moving the modified spots 13 to. Specifically, the distance between the condensing points C adjacent to each other in the Y direction is 2 μm, the pulse pitch of the laser light L is 5 μm, and the pulse energy of the laser light L is 0.3 μJ. Quality spot 13 was formed. In this case, as shown in FIG. 22, the extension amount of the crack 14 extending from the modified spot 13 to the laser light L incident side and the opposite side was about 100 μm.
　図３２は、第１実施例のレーザ加工方法及び半導体部材製造方法によって形成された改質スポット及び亀裂の画像であり、図３２の（ａ）は平面視での画像、図３２の（ｂ）は側面視での画像である。この第１実施例では、５３２ｎｍの波長を有するレーザ光ＬをＧａＮインゴット２０の表面２０ａからＧａＮインゴット２０の内部に入射させ、Ｙ方向に並ぶ６つの集光点Ｃを、Ｘ方向に沿って仮想面１５上を相対的に移動させることにより、仮想面１５に沿って複数の改質スポット１３を形成した。具体的には、まず、Ｙ方向において隣り合う集光点Ｃ間の距離を８μｍ、レーザ光Ｌのパルスピッチを１０μｍ、レーザ光Ｌのパルスエネルギーを０．３μＪとして、仮想面１５に沿って複数の改質スポット１３ａを形成した。続いて、Ｙ方向に並ぶ６つの集光点Ｃを先の状態からＹ方向に＋４μｍずらした状態で、Ｙ方向において隣り合う集光点Ｃ間の距離を８μｍ、レーザ光Ｌのパルスピッチを１０μｍ、レーザ光Ｌのパルスエネルギーを０．３μＪとして、仮想面１５に沿って複数の改質スポット１３ｂを形成した。続いて、Ｙ方向に並ぶ６つの集光点Ｃを先の状態からＹ方向に－４μｍずらした状態で、Ｙ方向において隣り合う集光点Ｃ間の距離を８μｍ、レーザ光Ｌのパルスピッチを５μｍ、レーザ光Ｌのパルスエネルギーを０．３μＪとして、仮想面１５に沿って複数の改質スポット１３を形成した。続いて、Ｙ方向に並ぶ６つの集光点Ｃを先の状態からＹ方向に＋４μｍずらした状態で、Ｙ方向において隣り合う集光点Ｃ間の距離を８μｍ、レーザ光Ｌのパルスピッチを５μｍ、レーザ光Ｌのパルスエネルギーを０．３μＪとして、仮想面１５に沿って複数の改質スポット１３を形成した。これにより、１回目に形成した改質スポット１３ａと３回目に形成した改質スポットとが互いに重なり、２回目に形成した改質スポット１３ｂと４回目に形成した改質スポットとが互いに重なっていると想定される。この場合、図３２の（ｂ）に示されるように、改質スポット１３からレーザ光Ｌの入射側及びその反対側に延びる亀裂１４の延び量が７０μｍ程度となった。 32A and 32B are images of modified spots and cracks formed by the laser processing method and the semiconductor member manufacturing method of the first embodiment. FIG. 32A is an image in plan view, and FIG. Is an image in side view. In the first embodiment, laser light L having a wavelength of 532 nm is made incident on the inside of the GaN ingot 20 from the surface 20a of the GaN ingot 20, and the six condensing points C arranged in the Y direction are virtual along the X direction. By relatively moving on the surface 15, a plurality of modified spots 13 were formed along the virtual surface 15. Specifically, first, the distance between the condensing points C adjacent to each other in the Y direction is 8 μm, the pulse pitch of the laser light L is 10 μm, and the pulse energy of the laser light L is 0.3 μJ. The modified spot 13a of No. 1 was formed. Then, with the six condensing points C aligned in the Y direction shifted from the previous state by +4 μm in the Y direction, the distance between the converging points C adjacent in the Y direction is 8 μm, and the pulse pitch of the laser light L is 10 μm. A plurality of modified spots 13b were formed along the virtual surface 15 by setting the pulse energy of the laser light L to 0.3 μJ. Then, with the six converging points C arranged in the Y direction shifted from the previous state by -4 μm in the Y direction, the distance between the converging points C adjacent to each other in the Y direction is 8 μm, and the pulse pitch of the laser light L is changed. A plurality of modified spots 13 were formed along the virtual surface 15 with the pulse energy of the laser beam L being 5 μm and 0.3 μJ. Subsequently, with the six condensing points C arranged in the Y direction shifted from the previous state by +4 μm in the Y direction, the distance between the converging points C adjacent in the Y direction is 8 μm, and the pulse pitch of the laser light L is 5 μm. A plurality of modified spots 13 were formed along the virtual surface 15 with the pulse energy of the laser light L set to 0.3 μJ. As a result, the modified spot 13a formed for the first time and the modified spot formed for the third time overlap each other, and the modified spot 13b formed for the second time and the modified spot formed for the fourth time overlap each other. Is assumed. In this case, as shown in (b) of FIG. 32, the extension amount of the crack 14 extending from the modified spot 13 to the laser light L incident side and the opposite side was about 70 μm.
　図３３の（ａ）及び（ｂ）は、第２実施例のレーザ加工方法及び半導体部材製造方法によって形成された改質スポット及び亀裂の画像であり、図３３の（ａ）は平面視での画像、図３３の（ｂ）は側面視での画像である。この第２実施例では、５３２ｎｍの波長を有するレーザ光ＬをＧａＮインゴット２０の表面２０ａからＧａＮインゴット２０の内部に入射させ、変形例のレーザ加工方法及び半導体部材製造方法と同様に、仮想面１５に沿って複数の改質スポット１３を形成した。複数の改質スポット１３ａを形成する際には、Ｙ方向において隣り合う集光点Ｃ間の距離を８μｍ、レーザ光Ｌのパルスピッチを１０μｍ、レーザ光Ｌのパルスエネルギーを０．３μＪとした。複数の改質スポット１３ｂを形成する際には、Ｙ方向において隣り合う集光点Ｃ間の距離を８μｍ、レーザ光Ｌのパルスピッチを１０μｍ、レーザ光Ｌのパルスエネルギーを１．８μＪとした。複数の改質スポット１３ｃを形成する際には、Ｙ方向において隣り合う集光点Ｃ間の距離を８μｍ、レーザ光Ｌのパルスピッチを５μｍ、レーザ光Ｌのパルスエネルギーを０．３μＪとした。複数の改質スポット１３ｄを形成する際には、Ｙ方向において隣り合う集光点Ｃ間の距離を８μｍ、レーザ光Ｌのパルスピッチを５μｍ、レーザ光Ｌのパルスエネルギーを０．３μＪとした。この場合、図３３の（ｂ）に示されるように、改質スポット１３からレーザ光Ｌの入射側及びその反対側に延びる亀裂１４の延び量が５０μｍ程度となった。 33A and 33B are images of modified spots and cracks formed by the laser processing method and the semiconductor member manufacturing method of the second embodiment, and FIG. 33A is a plan view. The image, (b) of FIG. 33, is an image in a side view. In the second embodiment, a laser beam L having a wavelength of 532 nm is made incident on the inside of the GaN ingot 20 from the surface 20a of the GaN ingot 20, and the virtual surface 15 is formed in the same manner as in the laser processing method and the semiconductor member manufacturing method of the modified example. A plurality of modified spots 13 were formed along the line. When forming the plurality of modified spots 13a, the distance between the condensing points C adjacent to each other in the Y direction was 8 μm, the pulse pitch of the laser light L was 10 μm, and the pulse energy of the laser light L was 0.3 μJ. When forming the plurality of modified spots 13b, the distance between the condensing points C adjacent to each other in the Y direction was 8 μm, the pulse pitch of the laser light L was 10 μm, and the pulse energy of the laser light L was 1.8 μJ. When forming the plurality of modified spots 13c, the distance between the condensing points C adjacent to each other in the Y direction was 8 μm, the pulse pitch of the laser light L was 5 μm, and the pulse energy of the laser light L was 0.3 μJ. When forming the plurality of modified spots 13d, the distance between the condensing points C adjacent to each other in the Y direction was 8 μm, the pulse pitch of the laser light L was 5 μm, and the pulse energy of the laser light L was 0.3 μJ. In this case, as shown in (b) of FIG. 33, the extension amount of the crack 14 extending from the modified spot 13 to the incident side of the laser light L and the opposite side thereof was about 50 μm.
　図３３の（ｃ）及び（ｄ）は、第３実施例のレーザ加工方法及び半導体部材製造方法によって形成された改質スポット及び亀裂の画像であり、図３３の（ｃ）は平面視での画像、図３３の（ｄ）は側面視での画像である。この第３実施例では、図３３の（ａ）及び（ｂ）に示される状態にある仮想面１５（すなわち、複数列の改質スポット１３が既に形成された仮想面１５）に沿って、更に、複数の改質スポット１３を形成した。具体的には、まず、Ｙ方向において隣り合う集光点Ｃ間の距離を８μｍ、レーザ光Ｌのパルスピッチを５μｍ、レーザ光Ｌのパルスエネルギーを０．１μＪとして、既に形成された複数列の改質スポット１３の列間の中心にそれぞれの列が位置するように複数列の改質スポット１３を形成した。この場合、図３３の（ｄ）に示されるように、改質スポット１３からレーザ光Ｌの入射側及びその反対側に延びる亀裂１４の延び量が６０μｍ程度となった。 33C and 33D are images of modified spots and cracks formed by the laser processing method and the semiconductor member manufacturing method of the third embodiment, and FIG. 33C is a plan view. The image, (d) of FIG. 33, is an image in a side view. In the third embodiment, further along the virtual plane 15 in the state shown in (a) and (b) of FIG. 33 (that is, the virtual plane 15 on which the reforming spots 13 in a plurality of rows have already been formed), A plurality of modified spots 13 were formed. Specifically, first, the distance between adjacent condensing points C in the Y direction is 8 μm, the pulse pitch of the laser light L is 5 μm, and the pulse energy of the laser light L is 0.1 μJ. A plurality of rows of reforming spots 13 were formed such that each row was positioned at the center between the rows of reforming spots 13. In this case, as shown in (d) of FIG. 33, the extension amount of the crack 14 extending from the modified spot 13 to the incident side of the laser light L and the opposite side thereof was about 60 μm.
　以上の実験結果から、仮想面１５に沿って既に形成された複数の改質スポット１３ａ及び複数の亀裂１４ａに重ならないように、仮想面１５に沿って複数の改質スポット１３ｂを形成すれば（第１実施例、第２実施例及び第３実施例）、改質スポット１３からレーザ光Ｌの入射側及びその反対側に延びる亀裂１４の延び量が抑制されることが分かった。なお、仮想面１５に沿って更に複数の改質スポット１３を形成する場合には、仮想面１５に沿って既に形成された複数の改質スポット１３ａ，１３ｂに重ならないように、仮想面１５に沿って複数の改質スポット１３を形成すれば（第２実施例及び第３実施例）、仮想面１５に渡る亀裂を形成し易くなる。
［第２実施形態のレーザ加工方法及び半導体部材製造方法］ From the above experimental results, if the modified spots 13b are formed along the virtual surface 15 so as not to overlap the modified spots 13a and the cracks 14a already formed along the virtual surface 15 (( 1st Example, 2nd Example, and 3rd Example), it turned out that the extension amount of the crack 14 extended from the modification spot 13 to the incident side of the laser beam L and the opposite side is suppressed. When forming a plurality of modified spots 13 along the virtual surface 15, the modified surface 13 is formed on the virtual surface 15 so as not to overlap the modified spots 13a and 13b already formed along the virtual surface 15. If a plurality of modified spots 13 are formed along the lines (second and third embodiments), it becomes easy to form a crack over the virtual surface 15.
[Laser Processing Method and Semiconductor Member Manufacturing Method of Second Embodiment]
　次に、第２実施形態のレーザ加工方法及び半導体部材製造方法を説明する。以下の説明では、上記第１実施形態と重複する説明は省略し、異なる点を説明する。 Next, a laser processing method and a semiconductor member manufacturing method according to the second embodiment will be described. In the following description, description that overlaps with the first embodiment will be omitted, and different points will be described.
　第２実施形態のレーザ加工方法及び半導体部材製造方法の対象物１１は、図３４に示されるように、ＧａＮによって例えば円板状に形成されたＧａＮウェハ（半導体ウェハ、半導体対象物）３０である。一例として、ＧａＮウェハ３０の直径は２ｉｎであり、ＧａＮウェハ３０の厚さは１００μｍである。第２実施形態のレーザ加工方法及び半導体部材製造方法は、ＧａＮウェハ３０から複数の半導体デバイス（半導体部材）４０を切り出すために実施される。一例として、半導体デバイス４０のＧａＮ基板部分の外形は１ｍｍ×１ｍｍであり、半導体デバイス４０のＧａＮ基板部分の厚さは数十μｍである。 As shown in FIG. 34, the object 11 of the laser processing method and the semiconductor member manufacturing method of the second embodiment is a GaN wafer (semiconductor wafer, semiconductor object) 30 formed of GaN into a disk shape, for example. .. As an example, the GaN wafer 30 has a diameter of 2 inches and the GaN wafer 30 has a thickness of 100 μm. The laser processing method and the semiconductor member manufacturing method of the second embodiment are carried out to cut out a plurality of semiconductor devices (semiconductor members) 40 from the GaN wafer 30. As an example, the outer shape of the GaN substrate portion of the semiconductor device 40 is 1 mm×1 mm, and the thickness of the GaN substrate portion of the semiconductor device 40 is several tens μm.
　まず、上述したレーザ加工装置１が、複数の仮想面１５のそれぞれに沿って改質領域１２を形成するレーザ加工工程を実施する。複数の仮想面１５のそれぞれは、ＧａＮウェハ３０の内部においてＧａＮウェハ３０の表面３０ａに対向する面であり、表面３０ａが延在する方向に並ぶように設定されている。本実施形態では、複数の仮想面１５のそれぞれは、表面３０ａに平行な面であり、例えば矩形状を呈している。複数の仮想面１５のそれぞれは、ＧａＮウェハ３０のオリエンテーションフラット３１に平行な方向及び垂直な方向に２次元状に並ぶように設定されている。 First, the laser processing apparatus 1 described above performs a laser processing step of forming the modified region 12 along each of the virtual surfaces 15. Each of the plurality of virtual surfaces 15 is a surface facing the surface 30a of the GaN wafer 30 inside the GaN wafer 30, and is set so as to be aligned in the direction in which the surface 30a extends. In the present embodiment, each of the plurality of virtual surfaces 15 is a surface parallel to the surface 30a and has, for example, a rectangular shape. Each of the plurality of virtual planes 15 is set to be arranged two-dimensionally in a direction parallel to the orientation flat 31 of the GaN wafer 30 and a direction perpendicular to the orientation flat 31.
　ＧａＮウェハ３０には、複数の仮想面１５のそれぞれを囲むように複数の周縁領域１６が設定されている。つまり、複数の仮想面１５のそれぞれは、ＧａＮウェハ３０の側面３０ｂに至っていない。周縁領域１６は、複数の仮想面１５のそれぞれに対応して複数設けられている。一例として、複数の仮想面１５のそれぞれに対応する周縁領域１６の幅（本実施形態では、隣り合う仮想面１５間の距離の半分）は３０μｍ以上である。ＧａＮウェハ３０において周縁領域１６で囲まれた領域は、改質領域１２を形成する対象となる加工対象領域Ｒである。加工対象領域Ｒは、仮想面１５を含む。 On the GaN wafer 30, a plurality of peripheral regions 16 are set so as to surround each of the plurality of virtual surfaces 15. That is, each of the plurality of virtual surfaces 15 does not reach the side surface 30b of the GaN wafer 30. A plurality of peripheral areas 16 are provided corresponding to each of the virtual surfaces 15. As an example, the width of the peripheral region 16 corresponding to each of the plurality of virtual surfaces 15 (half the distance between the adjacent virtual surfaces 15 in the present embodiment) is 30 μm or more. A region surrounded by the peripheral region 16 in the GaN wafer 30 is a processing target region R in which the modified region 12 is formed. The processing target region R includes the virtual surface 15.
　複数の仮想面１５のそれぞれに沿った改質領域１２の形成は、第１実施形態のレーザ加工方法及び半導体部材製造方法と同様に実施される。これにより、ＧａＮウェハ３０においては、図３５に示されるように、複数の仮想面１５のそれぞれに沿って、複数の改質スポット１３と複数の亀裂１４と窒素ガスＧとガリウムとを含む改質領域１２が形成される。図３５では、複数の改質スポット１３及び複数の亀裂１４が形成される範囲が破線で示されている。 The formation of the modified region 12 along each of the plurality of virtual surfaces 15 is performed in the same manner as the laser processing method and the semiconductor member manufacturing method of the first embodiment. Thereby, in the GaN wafer 30, as shown in FIG. 35, the reforming spots 13, the cracks 14, the nitrogen gas G, and the gallium are reformed along the respective virtual planes 15. Region 12 is formed. In FIG. 35, the range in which the plurality of modified spots 13 and the plurality of cracks 14 are formed is indicated by a broken line.
　続いて、半導体製造装置が、図３６に示されるように、ＧａＮウェハ３０の表面３０ａに複数の機能素子３２を形成する。複数の機能素子３２のそれぞれは、ＧａＮウェハ３０の厚さ方向から見た場合に１つの機能素子３２が１つの仮想面１５に含まれるように、形成される。機能素子３２は、例えば、フォトダイオード等の受光素子、レーザダイオード等の発光素子、メモリ等の回路素子等である。 Subsequently, the semiconductor manufacturing apparatus forms a plurality of functional elements 32 on the surface 30a of the GaN wafer 30, as shown in FIG. Each of the plurality of functional elements 32 is formed such that one functional element 32 is included in one virtual surface 15 when viewed from the thickness direction of the GaN wafer 30. The functional element 32 is, for example, a light receiving element such as a photodiode, a light emitting element such as a laser diode, a circuit element such as a memory, or the like.
　本実施形態では、表面３０ａに複数の機能素子３２を形成する際に、半導体製造装置が加熱装置として機能する。つまり、表面３０ａに複数の機能素子３２を形成する際に、半導体製造装置が、ＧａＮウェハ３０を加熱し、複数の仮想面１５のそれぞれにおいて、複数の改質スポット１３からそれぞれ延びる複数の亀裂１４を互いに繋げることにより、複数の仮想面１５のそれぞれにおいて、亀裂１７（すなわち、仮想面１５に渡る亀裂１７）を形成する。図３６では、複数の改質スポット１３及び複数の亀裂１４、並びに、亀裂１７が形成される範囲が破線で示されている。なお、半導体製造装置とは別の加熱装置が用いられてもよい。また、加熱以外の方法でＧａＮウェハ３０に何らかの力を作用させることにより、複数の亀裂１４を互いに繋げて亀裂１７を形成してもよい。また、仮想面１５に沿って複数の改質スポット１３を形成することにより、複数の亀裂１４を互いに繋げて亀裂１７を形成してもよい。 In the present embodiment, the semiconductor manufacturing apparatus functions as a heating device when forming the plurality of functional elements 32 on the surface 30a. That is, when forming the plurality of functional elements 32 on the surface 30 a, the semiconductor manufacturing apparatus heats the GaN wafer 30, and the plurality of cracks 14 extending from the plurality of modified spots 13 on each of the plurality of virtual surfaces 15 are formed. Are connected to each other, a crack 17 (that is, a crack 17 across the virtual surface 15) is formed in each of the plurality of virtual surfaces 15. In FIG. 36, the range in which the plurality of modified spots 13, the plurality of cracks 14, and the crack 17 are formed is indicated by broken lines. A heating device different from the semiconductor manufacturing device may be used. The cracks 17 may be formed by connecting the plurality of cracks 14 to each other by applying some force to the GaN wafer 30 by a method other than heating. Further, by forming the plurality of modified spots 13 along the virtual surface 15, the plurality of cracks 14 may be connected to each other to form the crack 17.
　ここで、ＧａＮウェハ３０においては、複数の改質スポット１３からそれぞれ延びる複数の亀裂１４内に窒素ガスが生じている。そのため、ＧａＮインゴット３０を加熱して窒素ガスを膨張させることにより、窒素ガスＧの圧力を利用して亀裂１７を形成することができる。しかも、周縁領域１６によって、当該周縁領域１６が囲む改質領域１２からＧａＮインゴット３０の外面（表面３０ａ及び側面３０ｂ）への亀裂１４の進展、及び、当該改質領域１２に隣接する他の改質領域１２への亀裂１４の進展が阻まれる。そのため、窒素ガスＧが外部及び隣接する他の改質領域１２へ逃げるのを抑制することができる。そのために、周縁領域１６の幅を３０μｍ以上とすることができる。 Here, in the GaN wafer 30, nitrogen gas is generated in the cracks 14 extending from the modified spots 13, respectively. Therefore, the crack 17 can be formed by utilizing the pressure of the nitrogen gas G by heating the GaN ingot 30 and expanding the nitrogen gas. Moreover, the peripheral region 16 causes the crack 14 to propagate from the modified region 12 surrounded by the peripheral region 16 to the outer surface (the surface 30a and the side face 30b) of the GaN ingot 30, and other modifications adjacent to the modified region 12. Propagation of the crack 14 into the quality region 12 is prevented. Therefore, it is possible to prevent the nitrogen gas G from escaping to the outside and the adjacent other reforming region 12. Therefore, the width of the peripheral region 16 can be set to 30 μm or more.
　以上の結果、半導体ウェハ（半導体対象物）として、次のＧａＮウェハ３０が得られる。図３６に示されるように、ＧａＮウェハ３０は、内部において、表面３０ａに対向する仮想面１５に沿って形成された改質領域１２と、改質領域１２を囲うように設けられた周縁領域１６と、を備える。改質領域１２は、複数の改質スポット１３と複数の改質スポット１３からそれぞれ延びる複数の亀裂１４と窒素ガスＧとを含む。改質領域１２は、表面３０ａが延在する方向に並ぶように複数設けられている。周縁領域１６は、改質スポット１３が形成されていない領域であって、囲う改質領域１２からＧａＮウェハ３０の外面への亀裂１４の進展を阻む。周縁領域１６は、複数の改質領域１２のそれぞれに対応して複数設けられている。周縁領域１６は、囲う改質領域１２から当該改質領域１２に隣接する他の改質領域１２への亀裂１４の進展を阻む。 As a result of the above, the following GaN wafer 30 is obtained as a semiconductor wafer (semiconductor object). As shown in FIG. 36, inside the GaN wafer 30, the modified region 12 formed along the virtual surface 15 facing the surface 30 a and the peripheral region 16 provided so as to surround the modified region 12. And The reforming region 12 includes a plurality of reforming spots 13, a plurality of cracks 14 extending from the plurality of reforming spots 13, and a nitrogen gas G, respectively. The plurality of modified regions 12 are provided so as to be arranged in the direction in which the surface 30a extends. The peripheral region 16 is a region where the modified spot 13 is not formed, and prevents the crack 14 from propagating from the surrounding modified region 12 to the outer surface of the GaN wafer 30. A plurality of peripheral regions 16 are provided corresponding to each of the plurality of modified regions 12. The peripheral region 16 prevents the crack 14 from propagating from the surrounding modified region 12 to another modified region 12 adjacent to the modified region 12.
　続いて、レーザ加工装置１がＧａＮウェハ３０を機能素子３２ごとに切断する。周縁領域１６を除去する周縁領域除去工程を実施する。これにより、改質領域１２に刺激を付与し、改質領域１２に含まれる窒素ガスＧの内圧解放効果も利用して、ＧａＮウェハ３０の一部を仮想面１５に沿って剥離する。剥離したＧａＮウェハ３０の一部に対して、改質領域１２を除去してウェハ化するウェハ化工程を実施する。以上の結果、図３７に示されるように、複数の亀裂１７のそれぞれを境界としてＧａＮウェハ３０から複数の半導体デバイス４０を取得する。このように、ＧａＮウェハ３０は、複数の仮想面１５のそれぞれに沿って切断される。なお、レーザ加工以外の機械加工（例えばブレードダイシング）等によって、ＧａＮウェハ３０を機能素子３２ごとに切断してもよい。 Subsequently, the laser processing apparatus 1 cuts the GaN wafer 30 into each functional element 32. A peripheral area removing step of removing the peripheral area 16 is performed. As a result, a stimulus is applied to the modified region 12, and the internal pressure releasing effect of the nitrogen gas G contained in the modified region 12 is also used to peel off a part of the GaN wafer 30 along the virtual surface 15. A wafer-forming step of removing the modified region 12 to form a wafer is performed on a part of the separated GaN wafer 30. As a result of the above, as shown in FIG. 37, a plurality of semiconductor devices 40 are obtained from the GaN wafer 30 with each of the plurality of cracks 17 as a boundary. In this way, the GaN wafer 30 is cut along each of the plurality of virtual planes 15. The GaN wafer 30 may be cut into each functional element 32 by mechanical processing (for example, blade dicing) other than laser processing.
　以上の工程のうち、レーザ加工工程までが、第２実施形態のレーザ加工方法である。また、以上の工程のうち、複数の亀裂１７のそれぞれを境界としてＧａＮウェハ３０から複数の半導体デバイス４０を取得する工程までが、第２実施形態の半導体部材製造方法である。 Among the above steps, up to the laser processing step is the laser processing method of the second embodiment. Further, among the above steps, the steps up to the step of obtaining the plurality of semiconductor devices 40 from the GaN wafer 30 with each of the plurality of cracks 17 as boundaries are the semiconductor member manufacturing method of the second embodiment.
　以上、第２実施形態のレーザ加工方法及び半導体部材製造方法においても、第１実施形態と同様な効果を奏する。 As described above, also in the laser processing method and the semiconductor member manufacturing method of the second embodiment, the same effect as that of the first embodiment is obtained.
　また、第２実施形態の半導体部材製造方法では、仮想面１５は、表面３０ａが延在する方向に並ぶように複数設定されている。改質領域１２及び周縁領域１６は、複数の仮想面１５のそれぞれに対応して複数設けられている。周縁領域１６は、囲う改質領域１２から当該改質領域１２に隣接する他の改質領域１２への亀裂１４の進展を阻む。これによれば、１つのＧａＮウェハ３０から複数の半導体デバイス４０の取得が可能となる。また、周縁領域１６によって改質領域１２から他の改質領域１２への亀裂１４の進展が阻まれていることから、改質領域１２から他の改質領域１２へ窒素ガスＧが逃げてしまうことを抑制することができ、窒素ガスＧの圧力を効果的に上昇ないし維持させることが可能となる。 Further, in the semiconductor member manufacturing method of the second embodiment, a plurality of virtual surfaces 15 are set so as to be arranged in the direction in which the surface 30a extends. A plurality of modified regions 12 and peripheral regions 16 are provided corresponding to each of the plurality of virtual surfaces 15. The peripheral region 16 prevents the crack 14 from propagating from the surrounding modified region 12 to another modified region 12 adjacent to the modified region 12. According to this, a plurality of semiconductor devices 40 can be obtained from one GaN wafer 30. Further, since the peripheral region 16 prevents the crack 14 from propagating from the reforming region 12 to another reforming region 12, the nitrogen gas G escapes from the reforming region 12 to the other reforming region 12. This can be suppressed, and the pressure of the nitrogen gas G can be effectively increased or maintained.
　また、第２実施形態の半導体部材製造方法では、レーザ加工工程の後、ＧａＮウェハ３０から周縁領域１６を除去することで、改質領域１２に刺激を付与し、改質領域１２の窒素ガスＧの圧力を解放しつつ、この解放される力も利用してＧａＮインゴット２０の一部を仮想面１５に沿って剥離することができる。 Further, in the semiconductor member manufacturing method of the second embodiment, after the laser processing step, the peripheral region 16 is removed from the GaN wafer 30 to give a stimulus to the modified region 12, and the nitrogen gas G of the modified region 12 is applied. While releasing the pressure of 1, the part of the GaN ingot 20 can be peeled off along the virtual plane 15 also by utilizing this released force.
　また、第２実施形態のＧａＮウェハ３０では、改質領域１２からＧａＮウェハ３０の外面へ亀裂１４が進展することが周縁領域１６によって阻まれており、改質領域１２に含まれる窒素ガスＧが亀裂１４を介して外部へ逃げてしまうことが抑制されている。よって、窒素ガスＧの圧力を効果的に上昇ないし維持させることが可能となる。当該内圧を利用し、仮想面１５に沿って亀裂１４を精度よく進展させることが可能となる。仮想面１５に渡る亀裂１７を境界としてＧａＮインゴット２０からＧａＮウェハ３０を取得することにより、好適なＧａＮウェハ３０の取得が可能となる。 Further, in the GaN wafer 30 of the second embodiment, the crack 14 is prevented from propagating from the modified region 12 to the outer surface of the GaN wafer 30 by the peripheral region 16, and the nitrogen gas G contained in the modified region 12 is prevented. Escape to the outside through the crack 14 is suppressed. Therefore, the pressure of the nitrogen gas G can be effectively increased or maintained. Using the internal pressure, the crack 14 can be accurately propagated along the virtual surface 15. By obtaining the GaN wafer 30 from the GaN ingot 20 with the crack 17 across the virtual plane 15 as the boundary, it is possible to obtain the suitable GaN wafer 30.
　また、第２実施形態のＧａＮウェハ３０では、改質領域１２は、Ｚ方向に並ぶように複数設けられている。周縁領域１６は、複数の改質領域１２のそれぞれに対応して複数設けられ、囲う改質領域１２から当該改質領域１２に隣接する他の改質領域１２への亀裂１４の進展を阻む。これによれば、１つのＧａＮウェハ３０から、複数の半導体デバイス４０を取得することが可能となる。改質領域１２から他の改質領域１２へ窒素ガスＧが逃げてしまうことを抑制することができ、窒素ガスＧの圧力を効果的に上昇ないし維持させることが可能となる。 Further, in the GaN wafer 30 of the second embodiment, a plurality of modified regions 12 are provided so as to be lined up in the Z direction. A plurality of peripheral regions 16 are provided corresponding to each of the plurality of modified regions 12, and prevent the crack 14 from propagating from the surrounding modified region 12 to another modified region 12 adjacent to the modified region 12. According to this, it becomes possible to obtain a plurality of semiconductor devices 40 from one GaN wafer 30. It is possible to prevent the nitrogen gas G from escaping from the reforming region 12 to another reforming region 12, and it is possible to effectively increase or maintain the pressure of the nitrogen gas G.
　なお、第２実施形態に係る半導体対象物は、機能素子３２ごとに切断された後で且つ周縁領域１６が除去される前の状態のＧａＮウェハ３０であってもよい。この場合、所望のタイミングで周縁領域１６を除去することで、所望のタイミングで半導体デバイス４０を得ることができる。半導体デバイス４０が剥離される前の状態でハンドリングが可能であるため、半導体デバイス４０の破損を抑制することができる。 The semiconductor object according to the second embodiment may be the GaN wafer 30 in a state after being cut for each functional element 32 and before the peripheral region 16 is removed. In this case, by removing the peripheral region 16 at a desired timing, the semiconductor device 40 can be obtained at a desired timing. Since handling is possible before the semiconductor device 40 is peeled off, damage to the semiconductor device 40 can be suppressed.
　本発明の一態様は、上述した実施形態に限定されない。 One aspect of the present invention is not limited to the above embodiment.
　例えば、レーザ光Ｌに関する各種数値は、上述したものに限定されない。ただし、亀裂１４が改質スポット１３からレーザ光Ｌの入射側及びその反対側に延びるのを抑制するためには、レーザ光Ｌのパルスエネルギーが０．１μＪ～１μＪであり且つレーザ光Ｌのパルス幅が２００ｆｓ～１ｎｓであってもよい。 For example, the various numerical values regarding the laser light L are not limited to those described above. However, in order to prevent the crack 14 from extending from the modified spot 13 to the incident side of the laser light L and the opposite side thereof, the pulse energy of the laser light L is 0.1 μJ to 1 μJ and the pulse of the laser light L is The width may be 200 fs to 1 ns.
　また、本発明の一態様に係るレーザ加工方法及び半導体部材製造方法によって加工される半導体対象物は、第１実施形態のＧａＮインゴット２０及び第２実施形態のＧａＮウェハ３０に限定されない。本発明の一態様に係る半導体部材製造方法によって製造される半導体部材は、第１実施形態のＧａＮウェハ３０及び第２実施形態の半導体デバイス４０に限定されない。１つの半導体対象物に１つの仮想面が設定されてもよい。半導体対象物の材料は、窒化物を含んでいればよい。半導体対象物の材料は、レーザ光Ｌによってガスを発生させる材料であればよい。 The semiconductor object processed by the laser processing method and the semiconductor member manufacturing method according to one aspect of the present invention is not limited to the GaN ingot 20 of the first embodiment and the GaN wafer 30 of the second embodiment. The semiconductor member manufactured by the semiconductor member manufacturing method according to one aspect of the present invention is not limited to the GaN wafer 30 of the first embodiment and the semiconductor device 40 of the second embodiment. One virtual surface may be set for one semiconductor object. The material of the semiconductor object may include nitride. The material of the semiconductor object may be any material that generates gas by the laser light L.
　また、上述した実施形態及び変形例において、複数の改質スポット１３の形成は、表面２０ａとは反対側から複数の仮想面１５ごとに順次に実施されてもよい。また、上述した実施形態及び変形例では、複数の改質スポット１３の形成は、表面２０ａとは反対側から複数の仮想面１５ごとに順次に実施されてもよい。また、上述した実施形態及び変形例では、レーザ光Ｌを空間光変調器４で分岐させ、複数の仮想面１５それぞれに１又は複数の改質スポット１３を同時形成してもよい。 In addition, in the above-described embodiment and modification, the formation of the plurality of modified spots 13 may be sequentially performed for each of the plurality of virtual surfaces 15 from the side opposite to the surface 20a. Further, in the above-described embodiment and modification, the formation of the plurality of modified spots 13 may be sequentially performed for each of the plurality of virtual surfaces 15 from the side opposite to the surface 20a. Further, in the above-described embodiment and modification, the laser light L may be branched by the spatial light modulator 4 and one or a plurality of modified spots 13 may be simultaneously formed on each of a plurality of virtual surfaces 15.
　また、第１実施形態のレーザ加工方法及び半導体部材製造方法では、複数の改質スポット１３の形成が表面２０ａ側の１つ又は複数の仮想面１５に沿って実施され、１つ又は複数のＧａＮウェハ３０が切り出された後に、ＧａＮインゴット２０の表面２０ａが研削され、再び、複数の改質スポット１３の形成が表面２０ａ側の１つ又は複数の仮想面１５に沿って実施されてもよい。 Further, in the laser processing method and the semiconductor member manufacturing method of the first embodiment, the formation of the plurality of modified spots 13 is performed along the one or more virtual surfaces 15 on the surface 20a side, and the one or more GaN. After the wafer 30 is cut out, the surface 20a of the GaN ingot 20 may be ground, and again, the plurality of modified spots 13 may be formed along the one or more virtual surfaces 15 on the surface 20a side.
　また、上述した実施形態及び変形例では、例えば周縁領域１６の範囲が一定範囲よりも狭い場合には、周縁領域除去工程を省略してもよい。上述した実施形態及び変形例では、例えば生じた窒素ガスＧの圧力が十分に高い場合には、加熱工程を省略してもよい。 Also, in the above-described embodiment and modification, for example, when the range of the peripheral area 16 is narrower than a certain range, the peripheral area removing step may be omitted. In the above-described embodiment and modification, the heating step may be omitted, for example, when the generated nitrogen gas G has a sufficiently high pressure.
　また、レーザ加工装置１は、上述した構成を有するものに限定されない。例えば、レーザ加工装置１は、空間光変調器４を備えていなくてもよい。 Moreover, the laser processing apparatus 1 is not limited to the one having the above-described configuration. For example, the laser processing device 1 may not include the spatial light modulator 4.
　また、上述した実施形態及び変形例における各構成には、上述した材料及び形状に限定されず、様々な材料及び形状を適用することができる。また、上述した実施形態又は変形例における各構成は、他の実施形態又は変形例における各構成に任意に適用することができる。 Also, the materials and shapes described above are not limited to the above-described embodiments and modifications, and various materials and shapes can be applied. Further, each configuration in the above-described embodiment or modified example can be arbitrarily applied to each configuration in another embodiment or modified example.
　１２…改質領域（他の改質領域）、１３，１３ａ，１３ｂ，１３ｃ，１３ｄ…改質スポット、１４，１４ａ，１４ｂ，１４ｃ，１４ｄ…亀裂、１５…仮想面、１６…周縁領域、１７…仮想面に渡る亀裂、２０…ＧａＮインゴット（半導体インゴット、半導体対象物）、２０ａ…表面、３０…ＧａＮウェハ（半導体ウェハ、半導体部材、半導体対象物）、３０ａ…表面、４０…半導体デバイス（半導体部材）、Ｈ１，Ｈ２，Ｈ３…孔、Ｇ…窒素ガス（ガス）、Ｌ…レーザ光。 12... modified area (other modified area), 13, 13a, 13b, 13c, 13d... modified spot, 14, 14a, 14b, 14c, 14d... crack, 15... virtual surface, 16... peripheral area, 17 ... Cracks across virtual plane, 20... GaN ingot (semiconductor ingot, semiconductor object), 20a... Surface, 30... GaN wafer (semiconductor wafer, semiconductor member, semiconductor object), 30a... Surface, 40... Semiconductor device (semiconductor) Member), H1, H2, H3... Hole, G... Nitrogen gas (gas), L... Laser light.

Claims (15)

  1. 　半導体対象物の表面から前記半導体対象物の内部にレーザ光を入射させることにより、前記半導体対象物の内部において、複数の改質スポットと前記複数の改質スポットからそれぞれ延びる複数の亀裂とガスとを含む改質領域を、前記表面に対向する仮想面に沿って形成する第１工程を備え、
    　前記第１工程では、前記改質スポットが形成されていない領域であって当該改質領域から前記半導体対象物の外面への前記亀裂の進展を阻む周縁領域を、当該改質領域を囲うように前記半導体対象物に設ける、レーザ加工方法。     By making a laser beam enter the inside of the semiconductor object from the surface of the semiconductor object, inside the semiconductor object, a plurality of modified spots and a plurality of cracks and gas extending from the plurality of modified spots, respectively. A modified step including a first step of forming a modified area along a virtual surface facing the surface,
    In the first step, a peripheral region that is a region in which the modified spot is not formed and that prevents the crack from propagating from the modified region to the outer surface of the semiconductor object is surrounded by the modified region. A laser processing method provided on the semiconductor object.
  2. 　前記周縁領域は、前記表面に対向する方向から見て、前記改質領域を囲う枠状を呈する、請求項１に記載のレーザ加工方法。 The laser processing method according to claim 1, wherein the peripheral region has a frame shape surrounding the modified region when viewed from a direction facing the surface.
  3. 　前記半導体対象物の材料は、窒化物を含む、請求項１又は２に記載のレーザ加工方法。 The laser processing method according to claim 1 or 2, wherein the material of the semiconductor object includes a nitride.
  4. 　前記ガスを外部へ逃がす孔を前記周縁領域に形成する工程を備える、請求項１～３の何れか一項に記載のレーザ加工方法。 The laser processing method according to any one of claims 1 to 3, further comprising forming a hole in the peripheral area for allowing the gas to escape to the outside.
  5. 　請求項１～４のいずれか一項に記載のレーザ加工方法を含む製造方法であって、
    　前記仮想面に渡る前記亀裂を境界として前記半導体対象物から半導体部材を取得する第２工程を備える、半導体部材製造方法。     A manufacturing method including the laser processing method according to claim 1.
    A semiconductor member manufacturing method comprising a second step of obtaining a semiconductor member from the semiconductor object with the crack extending over the virtual surface as a boundary.
  6. 　前記仮想面は、前記表面に対向する方向に並ぶように複数設定され、
    　前記改質領域及び前記周縁領域は、前記複数の仮想面のそれぞれに対応して複数設けられ、
    　前記周縁領域は、囲う前記改質領域から当該改質領域に隣接する他の改質領域への前記亀裂の進展を阻む、請求項５に記載の半導体部材製造方法。     A plurality of the virtual surfaces are set to line up in a direction facing the surface,
    A plurality of the modified regions and the peripheral region are provided corresponding to each of the plurality of virtual surfaces,
    The method for manufacturing a semiconductor member according to claim 5, wherein the peripheral region prevents the crack from propagating from the surrounding modified region to another modified region adjacent to the modified region.
  7. 　前記半導体対象物は、半導体インゴットであり、
    　前記半導体部材は、半導体ウェハである、請求項６に記載の半導体部材製造方法。     The semiconductor object is a semiconductor ingot,
    The semiconductor member manufacturing method according to claim 6, wherein the semiconductor member is a semiconductor wafer.
  8. 　前記仮想面は、前記表面が延在する方向に並ぶように複数設定され、
    　前記改質領域及び前記周縁領域は、複数の前記仮想面のそれぞれに対応して複数設けられ、
    　前記周縁領域は、囲う前記改質領域から当該改質領域に隣接する他の改質領域への前記亀裂の進展を阻む、請求項５に記載の半導体部材製造方法。     A plurality of the virtual surfaces are set so as to line up in a direction in which the surface extends,
    A plurality of the modified regions and the peripheral region are provided corresponding to each of the plurality of virtual surfaces,
    The method for manufacturing a semiconductor member according to claim 5, wherein the peripheral region prevents the crack from propagating from the surrounding modified region to another modified region adjacent to the modified region.
  9. 　前記半導体対象物は、半導体ウェハであり、
    　前記半導体部材は、半導体デバイスである、請求項８に記載の半導体部材製造方法。     The semiconductor object is a semiconductor wafer,
    The method for manufacturing a semiconductor member according to claim 8, wherein the semiconductor member is a semiconductor device.
  10. 　前記第１工程の後、前記半導体対象物を加熱することにより、前記ガスを膨張させて、前記亀裂を前記仮想面に沿って進展させる工程を備える、請求項５～９の何れか一項に記載の半導体部材製造方法。 10. The method according to claim 5, further comprising, after the first step, heating the semiconductor object to expand the gas and propagate the crack along the virtual surface. A method for manufacturing a semiconductor member as described above.
  11. 　前記第２工程では、前記改質領域に外部から刺激を付与することで、前記半導体対象物の一部を前記仮想面に沿って剥離する、請求項５～１０の何れか一項に記載の半導体部材製造方法。 11. The second step, according to claim 5, wherein a part of the semiconductor object is peeled off along the virtual surface by externally applying a stimulus to the modified region. Semiconductor member manufacturing method.
  12. 　前記第２工程では、前記半導体対象物から前記周縁領域を除去することで、前記半導体対象物の一部を前記仮想面に沿って剥離する、請求項５～１０の何れか一項に記載の半導体部材製造方法。 11. The second step, according to claim 5, wherein a part of the semiconductor object is peeled off along the virtual surface by removing the peripheral region from the semiconductor object. Semiconductor member manufacturing method.
  13. 　表面を有する半導体対象物であって、
    　前記半導体対象物の内部において、前記表面に対向する仮想面に沿って形成された改質領域と、
    　前記改質領域を囲うように設けられた周縁領域と、を備え、
    　前記改質領域は、複数の改質スポットと前記複数の改質スポットからそれぞれ延びる複数の亀裂とガスとを含み、
    　前記周縁領域は、前記改質スポットが形成されていない領域であって、囲う前記改質領域から前記半導体対象物の外面への前記亀裂の進展を阻む、半導体対象物。     A semiconductor object having a surface,
    Inside the semiconductor object, a modified region formed along a virtual surface facing the surface,
    A peripheral region provided so as to surround the modified region,
    The reforming region includes a plurality of reforming spots and a plurality of cracks and gases respectively extending from the plurality of reforming spots,
    The peripheral region is a region in which the modified spot is not formed, and prevents the crack from propagating from the surrounding modified region to the outer surface of the semiconductor target.
  14. 　半導体インゴットであって、
    　前記改質領域は、前記表面に対向する方向に並ぶように複数設けられ、
    　前記周縁領域は、前記複数の改質領域のそれぞれに対応して複数設けられ、
    　前記周縁領域は、囲う前記改質領域から当該改質領域に隣接する他の改質領域への前記亀裂の進展を阻む、請求項１３に記載の半導体対象物。     A semiconductor ingot,
    A plurality of the modified regions are provided so as to be aligned in a direction facing the surface,
    A plurality of the peripheral regions are provided corresponding to each of the plurality of modified regions,
    14. The semiconductor object according to claim 13, wherein the peripheral region prevents the crack from propagating from the surrounding modified region to another modified region adjacent to the modified region.
  15. 　半導体ウェハであって、
    　前記改質領域は、前記表面が延在する方向に並ぶように複数設けられ、
    　前記周縁領域は、前記複数の仮想面のそれぞれに対応して複数設けられ、
    　前記周縁領域は、囲う前記改質領域から当該改質領域に隣接する他の改質領域への前記亀裂の進展を阻む、請求項１３に記載の半導体対象物。     A semiconductor wafer,
    A plurality of the modified regions are provided so as to line up in a direction in which the surface extends,
    A plurality of the peripheral areas are provided corresponding to each of the plurality of virtual surfaces,
    14. The semiconductor object according to claim 13, wherein the peripheral region prevents the crack from propagating from the surrounding modified region to another modified region adjacent to the modified region.
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