WO2020130110A1 - Appareil d'usinage au laser - Google Patents

Appareil d'usinage au laser Download PDF

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Publication number
WO2020130110A1
WO2020130110A1 PCT/JP2019/049959 JP2019049959W WO2020130110A1 WO 2020130110 A1 WO2020130110 A1 WO 2020130110A1 JP 2019049959 W JP2019049959 W JP 2019049959W WO 2020130110 A1 WO2020130110 A1 WO 2020130110A1
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WIPO (PCT)
Prior art keywords
irradiation
semiconductor object
laser light
semiconductor
transmittance
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PCT/JP2019/049959
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English (en)
Japanese (ja)
Inventor
大祐 河口
陽太郎 和仁
泰則 伊ケ崎
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浜松ホトニクス株式会社
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Publication of WO2020130110A1 publication Critical patent/WO2020130110A1/fr

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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
    • 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
    • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
    • B23K26/03—Observing, e.g. monitoring, the workpiece
    • 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
    • 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 potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table 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

  • the present disclosure relates to a laser processing device.
  • a modified region is formed inside the semiconductor object, and a crack extending from the modified region is propagated, so that the semiconductor object is a semiconductor such as a semiconductor wafer.
  • a processing method for cutting out a member is known (see, for example, Patent Documents 1 and 2).
  • the method of forming the modified region greatly affects the state of the obtained semiconductor member.
  • the present disclosure has an object to provide a laser processing method and a semiconductor member manufacturing method capable of obtaining a suitable semiconductor member.
  • the present inventor has obtained the following first finding by proceeding with earnest studies to solve the above problems. That is, when a semiconductor spot containing gallium is irradiated with a laser beam to form a modified spot, gallium is deposited at the modified spot, resulting in a change in the overall transmittance of the semiconductor target and subsequent laser processing.
  • the irradiation conditions suitable for are changed. More specifically, the larger the amount of modified spots formed, the wider the gallium deposition range, and the lower the transmittance of the semiconductor object (the greater the absorption of laser light). Therefore, it is suitable for subsequent laser processing. Energy drops.
  • the laser processing apparatus measures a stage that supports a semiconductor object containing gallium, an irradiation unit that irradiates the semiconductor object supported by the stage with laser light, and the transmittance of the semiconductor object.
  • a first irradiation treatment for forming a plurality of modified spots and a deposition region containing gallium deposited in the plurality of modified spots along an imaginary surface facing the surface inside the object;
  • the control of the measurement unit the measurement process of measuring the transmittance of the semiconductor object, and after the measurement process, by the control of the irradiation unit, depending on the irradiation conditions according to the transmittance of the semiconductor object measured in the measurement process.
  • This laser processing apparatus includes an irradiation unit that irradiates a semiconductor object with laser light, a measurement unit that measures the transmittance of the semiconductor object, and a control unit that controls at least these.
  • the control unit first controls the irradiation unit to irradiate the inside of the semiconductor object with laser light, thereby forming a plurality of modified spots and a deposition region containing gallium. Subsequently, the control unit controls the measuring unit to measure the transmittance of the semiconductor object. Then, the control unit controls the irradiation unit to irradiate the inside of the semiconductor object with the laser light under the irradiation condition according to the previously measured transmittance. As a result, as described above, it is possible to obtain a suitable semiconductor member by laser processing with appropriate energy.
  • the controller moves from the surface to the inside of the semiconductor object when the transmittance of the semiconductor object measured in the measurement process is equal to or lower than the reference value.
  • the irradiation unit may be controlled so as to expand the deposition region by irradiating with laser light. In this way, the deposition region may be enlarged by irradiating the laser beam.
  • the present inventor found the following problems in the course of diligent studies to solve the above problems. That is, while forming a modified spot along the virtual surface inside the semiconductor object by irradiation of the laser light, when considering a case of cutting out a semiconductor member from the semiconductor object by developing a crack extending from the modified spot, In order to reduce the unevenness of the cut surface, it is effective to reduce the energy of the virtual surface of the laser light, while if the energy of the virtual surface of the laser light is too low, the modified spots and cracks will be formed. It cannot be caused.
  • the present inventor has further obtained the following second finding by paying attention to such a problem and proceeding with further studies. That is, first, by irradiating a semiconductor object containing gallium with laser light, along a virtual plane, a plurality of modified spots, and a deposition region containing gallium deposited in the plurality of modified spots, To form. Then, when the laser beam is irradiated again in a later step, even if the energy of the laser beam on the virtual surface is lowered below the processing threshold of the semiconductor object, the region containing gallium formed in advance can be expanded. it can. As a result, when a semiconductor member is cut out by forming a crack across a virtual surface, it is possible to reduce the unevenness of the cut surface.
  • the following invention was made based on these findings.
  • the energy on the virtual surface is the semiconductor.
  • the irradiation unit may be controlled so as to expand the deposition region by irradiating the inside of the semiconductor object with laser light from the surface so as to fall below the processing threshold value of the object.
  • the modified spot and the gallium deposition region are sufficient.
  • the irradiation area is controlled to irradiate the inside of the semiconductor object with the laser light so that the energy in the virtual surface becomes lower than the processing threshold value of the semiconductor object, thereby enlarging the deposition region.
  • the control unit collects the light when viewed from the direction intersecting the surface.
  • the deposition area is enlarged by irradiating the inside of the semiconductor object with laser light from the surface so that the light spot does not overlap the modified spot and the energy on the virtual surface falls below the processing threshold value of the semiconductor object.
  • the irradiation unit may be controlled. In this case, it is possible to obtain a suitable semiconductor member with reduced unevenness.
  • the control unit determines that the energy of the virtual surface is the semiconductor object when the transmittance of the semiconductor object measured in the measurement processing is higher than the reference value.
  • the irradiation unit may be controlled to irradiate the laser light from the surface to the inside of the semiconductor object according to the irradiation condition that is equal to or higher than the processing threshold value.
  • the control unit irradiates the inside of the semiconductor object with the laser beam while changing the irradiation condition under the control of the irradiation unit before the first irradiation processing, and the measurement unit By the control, the transmittance of the semiconductor object is measured for each irradiation condition to execute an acquisition process for acquiring the relationship between the irradiation condition and the transmittance, and the control unit sets the irradiation condition in the first irradiation process.
  • a plurality of modified spots are irradiated by irradiating the inside of the semiconductor object with laser light under an irradiation condition such that the transmittance of the semiconductor object after the first irradiation process becomes a reference value based on the relationship with the transmittance.
  • the irradiation unit may be controlled so as to form In this case, the relationship between the laser light irradiation condition and the transmittance of the semiconductor object is acquired prior to the first irradiation process. Therefore, in the subsequent first irradiation process (and subsequent second irradiation process), laser processing can be performed under appropriate irradiation conditions.
  • the stage includes a transmission unit that transmits the measurement light used in the measurement process, and the measurement unit has a light source that emits the measurement light toward the semiconductor object supported by the stage.
  • transmitted the transmission part may be provided, and the transmittance of the semiconductor object may be measured based on the detection result of a photodetector.
  • a laser processing apparatus includes a stage that supports a semiconductor object containing gallium, an irradiation unit that irradiates the semiconductor object supported by the stage with laser light, and a measurement unit that measures the transmittance of the semiconductor object. And a control unit that controls the irradiation unit and the measurement unit, and the control unit irradiates a laser beam from the surface of the semiconductor target object to the inside of the semiconductor target object under the control of the irradiation unit.
  • a measurement process of measuring the transmittance of the semiconductor object is executed under the control of the measuring unit.
  • This laser processing apparatus includes an irradiation unit that irradiates a semiconductor object with laser light, a measurement unit that measures the transmittance of the semiconductor object, and a control unit that controls at least these.
  • the control unit first controls the irradiation unit to irradiate the inside of the semiconductor object with laser light, thereby forming a plurality of modified spots and a deposition region containing gallium. Subsequently, the control unit controls the measuring unit to measure the transmittance of the semiconductor object. Therefore, it becomes possible to irradiate the inside of the semiconductor object with the laser light under the irradiation condition according to the transmittance obtained by this measurement. Therefore, as described above, it is possible to obtain a suitable semiconductor member by laser processing with appropriate energy.
  • the semiconductor objects under the same conditions, the semiconductor objects in the same lot, or the optimum processing conditions for a portion different from the portion used for the measurement of one semiconductor object can be obtained or obtained. It is possible to judge whether the product is a good product or a defective product by using the obtained transmittance. Furthermore, when a non-defective product or a defective product is determined, it is possible to change the processing conditions for the semiconductor object to be processed next based on the determination result.
  • FIG. 3 is a plan view of the GaN ingot shown in FIG. 2. It is a longitudinal 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 first example. It is a transverse cross section of a part of GaN ingot in one process of the laser processing method and semiconductor member manufacturing method of the 1st example. It is a longitudinal 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 first example.
  • FIG. 6 is an image of modified spots and cracks formed by the laser processing method and the semiconductor member manufacturing method of the second and third embodiments. It is a top view of a GaN wafer which is an object of a laser processing method and a semiconductor member manufacturing method of the 2nd example. It is a side view of a part of GaN wafer in one process of a laser processing method and a semiconductor member manufacturing method of a 2nd example. It is a side view of a part of GaN wafer in one process of a laser processing method and a semiconductor member manufacturing method of a 2nd example. It is a side view of a semiconductor device in one process of a laser processing method and a semiconductor member manufacturing method of a 2nd example.
  • 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 target 11 is a GaN ingot (semiconductor ingot, semiconductor target) 20 formed of gallium nitride (GaN) in a disk shape, for example.
  • the GaN ingot 20 has a diameter of 2 inches 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 GaN wafer 30 has a diameter of 2 inches and the GaN wafer 30 has a thickness of 100 ⁇ m.
  • the laser processing apparatus 1 described above forms a plurality of modified spots 13 along each of a plurality of 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.
  • each of the plurality of virtual surfaces 15 is a surface parallel to the surface 20a and has, for example, a circular 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.
  • the formation of the plurality of modified spots 13 is sequentially performed for each one virtual surface 15 from the side opposite to the surface 20a by the irradiation of the laser light L having a wavelength of 532 nm, for example. Since the formation of the plurality of modified spots 13 is the same on each of the plurality of virtual surfaces 15, the formation of the plurality of modified spots 13 along the virtual surface 15 closest to the surface 20a will be described below with reference to FIGS. This will be described in detail with reference to 11.
  • the arrow indicates the locus of the condensing point C of the laser light L.
  • the modified spots 13a, 13b, 13c, 13d described later may be collectively referred to as the modified spot 13
  • the cracks 14a, 14b, 14c, 14d described later may be collectively referred to as the crack 14.
  • the laser processing apparatus 1 causes the laser light L to enter the GaN ingot 20 from the surface 20 a and irradiate the laser light L along the virtual plane 15 (for example, a virtual plane).
  • a plurality of modified spots 13a are formed (two-dimensionally arranged along the entire surface 15) (step S1).
  • 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 (no hatching), and the range in which the crack 14a extends is shown by broken lines (the same applies to FIGS. 6 to 11). Further, at this time, the gallium deposited in each of the modified spots 13a spreads so as to enter the crack 14a, so that a deposition region R containing the deposited gallium is formed around the modified spot 13a. ..
  • 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 GaN ingot 20 from the surface 20 a and irradiates the laser light L along the virtual surface 15 (for example, A plurality of modified spots (second modified spots) 13b are formed so as to be arranged two-dimensionally along the entire virtual surface 15 (step S2). 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.
  • 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.
  • the cracks 14b extending from the modified spots 13b may be connected to the cracks 14a. 6 and 7, the modified spot 13b is shown by dot hatching, and the range in which the crack 14b extends is shown by broken lines (the same applies to FIGS. 8 to 11).
  • the gallium deposited in each of the modified spots 13b spreads so as to enter the crack 14b, so that a deposition region R containing the deposited gallium is formed around the modified spot 13b. ..
  • 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 apparatus 1 causes the laser light L to enter the GaN ingot 20 from the surface 20 a and irradiate the laser light L along the virtual surface 15 (for example, A plurality of modified spots (third modified spots) 13c are formed so as to be two-dimensionally arranged along the entire virtual surface 15 (step S3). Further, as shown in FIGS. 10 and 11, the laser processing apparatus 1 causes the laser light L to enter the GaN ingot 20 from the front surface 20 a and irradiate the laser light L along the virtual surface 15 (for example, a virtual surface). A plurality of modified spots (third modified spots) 13d are formed so as to be two-dimensionally arranged along the entire surface 15 (step S4). 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.
  • 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. 10 and 11).
  • 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.
  • the gallium deposited in each of the reformed spots 13c and 13d spreads so as to enter the cracks 14c and 14d, so that the deposited gallium is deposited around the reformed spots 13c and 13d. Region R is formed.
  • 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.
  • a heating device including a heater or the like heats the GaN ingot 20 to connect the plurality of cracks 14 extending from the plurality of modified spots 13 to each other on each of the plurality of virtual planes 15, thereby being shown in FIG.
  • a crack 17 (hereinafter, simply referred to as “crack 17”) that extends over the virtual surface 15 is formed in each of the plurality of virtual surfaces 15.
  • a range in which the plurality of modified spots 13, the plurality of cracks 14, and the crack 17 are formed is shown by a broken line.
  • 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.
  • the GaN ingot 20 nitrogen gas is generated in a plurality of cracks 14 extending from the plurality of modified spots 13, respectively. Therefore, by heating the GaN ingot 20 and expanding the nitrogen gas, the crack 17 can be formed by utilizing the pressure (internal pressure) of the nitrogen gas. Moreover, since the peripheral region 16 prevents the cracks 14 from propagating to the outside of the virtual surface 15 surrounded by the peripheral region 16 (for example, the side surface 20b of the GaN ingot 20), nitrogen generated in the cracks 14 is prevented. It is possible to prevent the gas from escaping to the outside of the virtual surface 15.
  • the peripheral area 16 is a non-modified area that does not include the modified spot 13, and when the crack 17 is formed on the virtual surface 15 surrounded by the peripheral area 16, the virtual surface 15 surrounded by the peripheral area 16 is formed. It is a region that prevents the plurality of cracks 14 from propagating to the outside. Therefore, the width of the peripheral region 16 can be set to 30 ⁇ m or more.
  • the grinding device grinds (polishs) the portions of the GaN ingot 20 corresponding to the plurality of peripheral regions 16 and the plurality of virtual surfaces 15, respectively, so that a plurality of cracks 17 are formed as shown in FIG.
  • a plurality of GaN wafers 30 are obtained from the GaN ingot 20 with each of them as a boundary (step S5). In this way, the GaN ingot 20 is cut along each of the virtual surfaces 15.
  • portions of the GaN ingot 20 corresponding to the plurality of peripheral regions 16 may be removed by mechanical processing other than grinding, laser processing, or the like.
  • the laser processing method of the first example includes up to the step of forming the plurality of modified spots 13 along each of the plurality of virtual surfaces 15. Further, among the above steps, the steps up to the step of obtaining the plurality of GaN wafers 30 from the GaN ingot 20 with each of the plurality of cracks 17 as the boundary are the semiconductor member manufacturing method of the first example.
  • the plurality of modified spots 13a are formed along each of the plurality of virtual surfaces 15 so as not to overlap the plurality of modified spots 13a and the plurality of cracks 14a. Then, a plurality of modified spots 13b are formed along each of the plurality of virtual surfaces 15. Furthermore, in the laser processing method of the first example, a plurality of modified spots 13c and 13d are formed along each of the plurality of virtual surfaces 15 so as not to overlap the plurality of modified spots 13a and 13b. Thereby, the plurality of modified spots 13 can be accurately formed along each of the plurality of virtual surfaces 15, and as a result, the crack 17 can be formed accurately along each of the plurality of virtual surfaces 15. It will be possible.
  • the laser processing method of the first example it is possible to obtain a plurality of suitable GaN wafers 30 by obtaining a plurality of GaN wafers 30 from the GaN ingot 20 with each of the plurality of cracks 17 as a boundary. ..
  • the laser processing apparatus 1 that implements the laser processing method of the first example, it is possible to accurately form the crack 17 along each of the plurality of virtual surfaces 15, and thus a plurality of suitable GaN layers can be formed.
  • the wafer 30 can be acquired.
  • the plurality of modified spots 13a are formed so that the plurality of cracks 14a extending from the plurality of modified spots 13a are not connected to each other. Thereby, the plurality of modified spots 13b can be formed more accurately along the virtual surface 15.
  • the condensing point C of the pulsed laser light L is moved along the virtual surface 15 to form the modified spots 13a in a plurality of rows and pulsed.
  • the plurality of rows of modified spots 13b are formed.
  • gallium nitride contained in the material of the GaN ingot 20 is decomposed by the irradiation of the laser beam L, gallium is deposited in the cracks 14a extending from the modified spots 13a. Then, the deposition region R is formed, and the laser light L is easily absorbed by the gallium. Therefore, forming the plurality of modified spots 13b so as not to overlap the crack 14a is effective in accurately forming the plurality of modified spots 13b along the virtual surface 15.
  • the crack 17 can be easily formed by utilizing the pressure of the nitrogen gas.
  • the cracks 17 can be accurately formed along each of the virtual surfaces 15 by the steps included in the laser processing method of the first example.
  • the plurality of virtual surfaces 15 are set to be aligned in the direction facing the surface 20 a of the GaN ingot 20. This makes it possible to obtain a plurality of GaN wafers 30 from one GaN ingot 20.
  • FIG. 14 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. 15A and 15B 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 separated surface (surface formed by the crack 17) of the GaN wafer 30.
  • FIG. 16 is an image of a peeled surface of a GaN wafer formed by a laser processing method and a semiconductor member manufacturing method of another example
  • FIGS. 17A and 17B show the peeled surface of 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 the first and second steps of the laser processing method and the semiconductor member manufacturing method of the first embodiment.
  • the 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 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 ⁇ m.
  • 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 along the virtual surface 15. Was found to be formed with high precision. 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 a virtual surface 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.
  • a plurality of modified spots 13a and a plurality of modified spots 13a are provided so as not to overlap the cracks 14a extending from the modified spots 13a. It can be seen that the formation of the spots 13b is extremely important in reducing the unevenness appearing on the separated surface of the GaN wafer 30.
  • FIG. 20A and 20B are images of cracks formed during the laser processing method and the semiconductor member manufacturing method of an example
  • FIG. 20B is a rectangle in FIG. 20A. It is an enlarged image in the frame.
  • 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 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.
  • the crack that propagated from the processed region to the unprocessed region largely deviated from the virtual surface 15 in the unprocessed region.
  • FIG. 21(a) and 21(b) are images of cracks formed during the laser processing method and the semiconductor member manufacturing method of another example, and FIG. 21(b) is FIG. 21(a). 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 at the center between the rows.
  • 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. 21, the crack propagated from the processing region 1 to the processing region 2 was not largely deviated from the virtual surface 15 in the processing region 2.
  • FIG. 22 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. 23A and 23B are images of modified spots and cracks formed by the laser processing method and the semiconductor member manufacturing method of the first embodiment.
  • FIG. 23A 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 first modified spot 13a and the third modified spot 13 overlap each other, and the second modified spot 13b and the fourth modified spot 13 overlap each other. It is assumed that In this case, as shown in (b) of FIG. 23, 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 70 ⁇ m.
  • FIG. 24A and 24B 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. 24A is a plan view.
  • An image, (b) of FIG. 24, is an image in a side view.
  • 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 first and second steps of the laser processing method and the semiconductor member manufacturing method of the first example.
  • 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 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 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 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 1.8 ⁇ 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. 24C and 24D 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. 24C is a plan view.
  • An image, (d) of FIG. 24, 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 beam L and the opposite side thereof was about 60 ⁇ m.
  • the object 11 of the laser processing method and the semiconductor member manufacturing method of the second example is a GaN wafer (semiconductor wafer, semiconductor object) 30 formed of GaN in a disk shape, for example, as shown in FIG.
  • 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 example are performed 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.
  • the laser processing apparatus 1 described above forms a plurality of modified spots 13 along each of a plurality of 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.
  • 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.
  • the width of the peripheral region 16 corresponding to each of the plurality of virtual surfaces 15 is 30 ⁇ m or more.
  • the formation of the plurality of modified spots 13 along each of the plurality of virtual surfaces 15 is performed in the same manner as steps S1 to S4 of the laser processing method and the semiconductor member manufacturing method of the first example.
  • a plurality of modified spots 13 that is, modified spots 13a, 13b, 13c, 13d
  • a plurality of modified spots 13 are provided along each of the plurality of virtual planes 15.
  • 14 that is, the cracks 14a, 14b, 14c, 14d
  • 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. 27, 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.
  • the peripheral region 16 prevents the plurality of cracks 14 from propagating to the outside of the virtual surface 15 surrounded by the peripheral region 16 (for example, the adjacent virtual surface 15 and the side surface 30b of the GaN wafer 30), the plurality of cracks is prevented. It is possible to prevent the nitrogen gas generated in 14 from escaping to the outside of the virtual surface 15.
  • the peripheral area 16 is a non-modified area that does not include the modified spot 13, and when the crack 17 is formed on the virtual surface 15 surrounded by the peripheral area 16, the virtual surface 15 surrounded by the peripheral area 16 is formed. It is a region that prevents the plurality of cracks 14 from propagating to the outside. Therefore, the width of the peripheral region 16 can be set to 30 ⁇ m or more.
  • the laser processing device cuts the GaN wafer 30 into each functional element 32, and the grinding device grinds the portions corresponding to each of the plurality of virtual planes 15, as shown in FIG. 28.
  • a plurality of semiconductor devices 40 are obtained from the GaN wafer 30 with each of the plurality of cracks 17 as a boundary (step S6). In this way, the GaN wafer 30 is cut along each of the plurality of virtual planes 15. In this step, 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 method of the second example includes up to the step of forming the plurality of modified spots 13 along each of the plurality of virtual surfaces 15. 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 the boundary are the semiconductor member manufacturing method of the second example.
  • the laser processing method of the second example As described above, according to the laser processing method of the second example, as in the laser processing method of the first example, it is possible to accurately form the plurality of modified spots 13 along each of the plurality of virtual surfaces 15. As a result, the crack 17 can be accurately formed along each of the plurality of virtual surfaces 15. Therefore, according to the laser processing method of the second example, it is possible to obtain a plurality of suitable semiconductor devices 40 by obtaining a plurality of semiconductor devices 40 from the GaN wafer 30 with each of the plurality of cracks 17 as a boundary. .. It is also possible to reuse the GaN wafer 30 after cutting out the plurality of semiconductor devices 40.
  • the laser processing apparatus 1 that implements the laser processing method of the second example, it is possible to accurately form the crack 17 along each of the virtual surfaces 15, and thus a plurality of suitable semiconductors can be formed.
  • the device 40 can be acquired.
  • the plurality of modified spots 13a are formed so that the plurality of cracks 14a extending from the plurality of modified spots 13a are not connected to each other. Thereby, the plurality of modified spots 13b can be formed more accurately along the virtual surface 15.
  • the condensing point C of the pulsed laser light L is moved along the virtual plane 15 to form a plurality of rows of modified spots 13a and pulsed.
  • the plurality of rows of modified spots 13b are formed.
  • gallium nitride contained in the material of the GaN wafer 30 is decomposed by the irradiation of the laser light L, gallium is deposited in the cracks 14a extending from the modified spots 13a. Then, the laser light L is easily absorbed by the gallium. Therefore, forming the plurality of modified spots 13b so as not to overlap the crack 14a is effective in accurately forming the plurality of modified spots 13b along the virtual surface 15.
  • the crack 17 can be easily formed by utilizing the pressure of the nitrogen gas.
  • the cracks 17 can be accurately formed along each of the virtual surfaces 15 by the steps included in the laser processing method of the second embodiment. Therefore, it is possible to obtain a plurality of suitable semiconductor devices 40.
  • the plurality of virtual surfaces 15 are set to be aligned in the direction in which the surface 30a of the GaN wafer 30 extends. This makes it possible to obtain a plurality of semiconductor devices 40 from one GaN wafer 30.
  • 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 width is 200 fs or more. It can be 1 ns.
  • the semiconductor object processed by the laser processing method and the semiconductor member manufacturing method is not limited to the GaN ingot 20 of the first example and the GaN wafer 30 of the second example.
  • the semiconductor member manufactured by the semiconductor member manufacturing method is not limited to the GaN wafer 30 of the first example and the semiconductor device 40 of the second example.
  • One virtual surface may be set for one semiconductor object.
  • the material of the semiconductor object may be SiC. Even in that case, according to the laser processing method and the semiconductor member manufacturing method, as described below, it is possible to accurately form a crack extending over the virtual surface along the virtual surface.
  • FIG. 29A and 29B are images (images in side view) of the cracks of the SiC wafer formed by the laser processing method and the semiconductor member manufacturing method of the comparative example, and FIG. 29A is an enlarged image within a rectangular frame in FIG.
  • laser light having a wavelength of 532 nm is made incident on the inside of the SiC wafer from the surface of the SiC wafer, and the six converging points arranged in the Y direction are relatively moved on the virtual surface along the X direction. By doing so, a plurality of modified spots were formed along the virtual surface.
  • the distance between the condensing points C adjacent to each other in the Y direction was 2 ⁇ m
  • the pulse pitch of the laser light was 15 ⁇ m
  • the pulse energy of the laser light was 4 ⁇ J.
  • a crack extending in a direction inclined by 4° to 5° with respect to the virtual plane occurred.
  • FIG. 30A and 30B are images (images in side view) of the cracks of the SiC wafer formed by the laser processing method and the semiconductor member manufacturing method of the example, and FIG. 30 is an enlarged image in the rectangular frame in FIG.
  • laser light having a wavelength of 532 nm is made to enter the inside of the SiC wafer from the surface of the SiC wafer, and the same steps as the first and second steps of the laser processing method and the semiconductor member manufacturing method of the first embodiment are performed.
  • a plurality of modified spots were formed along the virtual surface.
  • FIG. 31 is an image of the peeled surface of the SiC wafer formed by the laser processing method and the semiconductor member manufacturing method of the example, and FIGS. 32A and 32B show the height of the peeled surface shown in FIG. It is a profile. In this case, the unevenness appearing on the peeled surface of the SiC wafer was suppressed to about 2 ⁇ m.
  • the SiC wafers used in the above-described comparative examples and examples are 4H-SiC wafers having an off angle of 4 ⁇ 0.5°, and the direction in which the focusing point of the laser light is moved is the m-axis direction. Is.
  • the method of forming the plurality of modified spots 13a, 13b, 13c, 13d is not limited to the above.
  • the plurality of modified spots 13a may be formed such that the plurality of cracks 14a extending from the plurality of modified spots 13a are connected to each other.
  • the plurality of modified spots 13b may be formed so as not to overlap the plurality of modified spots 13a. Even if the plurality of reforming spots 13b overlap the plurality of cracks 14a extending from the plurality of reforming spots 13a, if the plurality of reforming spots 13b do not overlap the plurality of reforming spots 13a, the plurality of reforming spots 13b do not overlap. 13a and 13b are accurately formed along the virtual surface 15.
  • the method of forming the plurality of modified spots 13c and 13d is arbitrary, and the plurality of modified spots 13c and 13d may not be formed.
  • FIG. 33 for example, by rotating the GaN ingot 20, a plurality of condensing points arranged in the radial direction are relatively rotated (dashed-dotted arrows), and a plurality of rows of modified spots are formed.
  • 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 laser processing method and the semiconductor member manufacturing method of the first example, the formation of the plurality of modified spots 13 is performed along the one or more virtual surfaces 15 on the front surface 20a side, and the one or more GaN wafers. After the 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 region 16 may not be formed.
  • the peripheral region 16 is not formed in the laser processing method and the semiconductor member manufacturing method of the first example, after forming the plurality of modified spots 13 along each of the plurality of virtual surfaces 15, for example, the GaN ingot 20 is formed. It is also possible to obtain a plurality of GaN wafers 30 by performing etching on them.
  • 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.
  • the present inventor has obtained the following first finding by conducting earnest studies. That is, when a semiconductor spot containing gallium is irradiated with a laser beam to form a modified spot, gallium is deposited at the modified spot, resulting in a change in the overall transmittance of the semiconductor target and subsequent laser processing.
  • the irradiation conditions suitable for are changed. More specifically, the larger the amount of modified spots formed, the wider the gallium deposition range, and the lower the transmittance of the semiconductor object (the greater the absorption of laser light). Therefore, it is suitable for subsequent laser processing. Energy drops.
  • FIG. 35 is a diagram showing a laser processing apparatus according to the embodiment.
  • the laser processing apparatus 1A is different from the laser processing apparatus 1 shown in FIG. 1 in that the laser processing apparatus 1A further includes a measuring unit 50 and that the laser processing apparatus 1A includes a stage 2A instead of the stage 2.
  • the laser processing apparatus 1 is different.
  • the light source 3, the spatial light modulator 4, and the condenser lens 5 form an irradiation unit 45.
  • the laser processing apparatus 1A includes the stage 2A that supports the GaN wafer 30, the irradiation unit 45 that irradiates the GaN wafer 30 supported by the stage 2A with the laser light L, and the measurement unit that measures the transmittance of the GaN wafer 30. 50 and a control unit 6 that controls the irradiation unit 45 and the measurement unit 50.
  • the stage 2A includes a transmission part 2T that transmits the measurement light IL used for measurement.
  • the measurement unit 50 includes a light source 51 that irradiates the GaN wafer 30 supported by the stage 2A with the measurement light IL, and a photodetector 52 that detects the measurement light IL transmitted through the GaN wafer 30 and the transmission unit 2T. Then, the transmittance of the GaN wafer 30 is measured based on the detection result of the photodetector 52.
  • the control unit 6 first executes the first irradiation process under the control of the irradiation unit 45.
  • the first irradiation processing is performed by irradiating the inside of the GaN wafer 30 with the laser light L from the surface 30a of the GaN wafer 30 to cause a plurality of modifications along the virtual plane 15 facing the surface 30a inside the GaN wafer 30.
  • This is a process for forming a quality spot 13 and a deposition region R containing gallium deposited in a plurality of modified spots 13. More specifically, in this first irradiation process, the control unit 6 executes the steps S1 to S3 of the above-described example to form the modified spots 13a to 13c on the GaN wafer 30. At the same time, a gallium precipitation region R is formed in the crack 14.
  • FIG. 36 is a graph showing the measured transmittance.
  • the graph T0 shows the transmittance of the GaN wafer 30 before formation of the modified spot.
  • the graph T1 shows the transmittance of the GaN wafer 30 in the state in which the modified spot 13a and the corresponding deposition region R are formed by performing the step S1.
  • the graph T2 shows the transmittance of the GaN wafer 30 in the state in which the modified spot 13b and the corresponding deposition region R are formed by performing the step S2.
  • the graph T3 shows the transmittance of the GaN wafer 30 in the state where the modified spot 13c and the corresponding deposition region R are formed by performing the step 3. From these graphs, it is understood that the transmittance of the GaN wafer 30 decreases as the modified spot 13 (precipitation region) is formed.
  • the irradiation conditions of the laser light L when forming the modified spots 13a to 13c can be specified as follows, for example. First, as the pulse energy of the laser light L increases, the deposition region R formed around the modified spot 13 tends to increase. Therefore, when the distance between the condensing points C of the laser light L (for example, in the Y direction) is relatively increased (the modified spot 13 and the deposition region R are relatively coarsely formed), the subsequent laser is used.
  • the pulse energy of the laser light L can be increased from the viewpoint of enlarging the deposition region R by irradiation with light.
  • the laser light is used. Even if the pulse energy of is reduced, the deposition region R can be enlarged by irradiation with laser light in a later step.
  • the pulse pitch of the laser light L is fixed to 10 ⁇ m
  • the pulse energy of the laser light L is set to about 2 ⁇ J.
  • the deposition region R can be enlarged by irradiation with laser light in a later step.
  • the pulse energy of the laser light L is set to about 0.67 ⁇ J, so that the deposition region is irradiated by the laser light in a later step.
  • R can be expanded.
  • the pulse energy of the laser light L is set to about 0.33 ⁇ J, so that the deposition region is formed by the irradiation of the laser light in a later step. R can be expanded.
  • control unit 6 can determine whether the transmittance of the GaN wafer 30 is less than or equal to the reference value.
  • the reference value of the transmittance of the GaN wafer 30 can be set to 0.5 (50%), for example.
  • the transmittance of the GaN wafer 30 after the first irradiation process once is about 0.6 to 0.7, which is higher than the reference value.
  • the second process is a process of irradiating the laser light L from the surface 30a to the inside of the GaN wafer 30 under the irradiation condition according to the transmittance of the GaN wafer 30 measured in the measurement process under the control of the irradiation unit 45.
  • the transmittance of the GaN wafer 30 measured in the measurement process is equal to or lower than the reference value.
  • the transmittance being equal to or lower than the reference value means that the modified spot 13 and the deposition region R are sufficiently formed inside the GaN wafer 30. In this case, as shown in FIGS.
  • control unit 6 controls the laser from the surface 30a to the inside of the GaN wafer 30 under the irradiation condition such that the energy in the virtual plane becomes relatively small.
  • the irradiation unit 45 is controlled so as to enlarge the deposition region R.
  • the control unit 6 irradiates the inside of the GaN wafer 30 with the laser light L from the surface 30a so that the energy in the virtual plane becomes lower than the processing threshold of the GaN wafer 30.
  • the irradiation unit 45 may be controlled so as to enlarge R.
  • the control unit 6 may prevent the condensing point C from overlapping the modified spot 13 when viewed from the direction (Z direction) intersecting the surface 30a.
  • the condensing point C may be arranged so as not to overlap the crack 14 and the deposition region R in addition to the modified spot 13.
  • An example of irradiating the laser light L with energy below the processing threshold of the GaN wafer 30 is based on the following knowledge. That is, first, by irradiating a semiconductor object containing gallium with laser light, along a virtual plane, a plurality of modified spots, and a deposition region containing gallium deposited in the plurality of modified spots, To form. Then, when the laser beam is irradiated again in a later step, the condensing point of the laser beam is prevented from overlapping the preformed reformed spots, and the energy of the laser beam on the virtual plane is processed. Even if the amount is lowered below the threshold value, the deposition region containing gallium that is formed in advance can be expanded. As a result, when a semiconductor member is cut out by forming a crack across a virtual surface, it is possible to reduce the unevenness of the cut surface.
  • the transmittance of the GaN wafer 30 measured in the measurement process is higher than the reference value.
  • the laser is irradiated from the surface 30a into the GaN wafer 30.
  • the irradiation unit 45 is controlled to emit the light L.
  • the control unit 6 irradiates the laser light L from the surface 30a to the inside of the GaN wafer 30 under the irradiation condition that the energy in the virtual surface 15 is equal to or more than the processing threshold of the GaN wafer 30,
  • the irradiation unit 45 is controlled. That is, in this case, the step S4 in the above example is further executed to form the modified spot 13d and the corresponding deposition region R. Then, the transmittance of the GaN wafer 30 further decreases.
  • the laser processing apparatus 1A includes the irradiation unit 45 that irradiates the GaN wafer 30 with the laser light L, the measurement unit 50 that measures the transmittance of the GaN wafer 30, and the control unit 6 that controls at least them. , Are provided.
  • the control unit 6 first controls the irradiation unit 45 to irradiate the inside of the GaN wafer 30 with the laser light L, thereby forming the plurality of modified spots 13 and the deposition region R containing gallium. Subsequently, the control unit 6 controls the measuring unit 50 to measure the transmittance of the GaN wafer 30.
  • control unit 6 controls the irradiation unit 45 to irradiate the inside of the GaN wafer 30 with the laser light L under the irradiation condition according to the previously measured transmittance.
  • the control unit 6 changes the surface 30a from the surface 30a.
  • the irradiation unit 45 is controlled so that the deposition region R is enlarged by irradiating the inside of the GaN wafer 30 with the laser light L. In this way, the deposition region R may be enlarged by the irradiation of the laser light L.
  • the energy in the virtual plane 15 is the GaN wafer.
  • the irradiation unit 45 may be controlled so as to expand the deposition region R by irradiating the inside of the GaN wafer 30 with the laser light L so as to fall below the processing threshold of 30.
  • the control unit 6 determines that the modified spot 13 and the gallium deposition region R are separated.
  • the precipitation region R is irradiated by irradiating the inside of the GaN wafer 30 with the laser light L so that the energy in the virtual surface 15 becomes lower than the processing threshold of the GaN wafer 30. Expanding. As a result, as described above, it is possible to obtain a suitable semiconductor member with reduced unevenness by cutting out with the crack across the virtual surface 15 as a boundary.
  • the control unit 6 sees from the direction intersecting the surface 30a. Irradiating the laser light L from the surface 30a into the GaN wafer 30 so that the condensing point C does not overlap the modified spot 13 and the energy on the virtual surface 15 falls below the processing threshold of the GaN wafer 30.
  • the irradiation unit 45 may be controlled so that the deposition region R is enlarged by. In this case, it is possible to obtain a suitable semiconductor member with reduced unevenness.
  • the controller 6 controls the virtual surface 15 when the transmittance of the GaN wafer 30 measured in the measurement process is higher than the reference value.
  • the irradiation unit 45 is controlled to irradiate the laser light L from the surface 30a to the inside of the GaN wafer 30 under the irradiation condition in which the energy in is equal to or higher than the processing threshold of the GaN wafer 30.
  • the second irradiation process causes It is possible to form the additional modified spot 13 and the deposition region R.
  • the stage 2A includes the transmission part 2T that transmits the measurement light IL used in the measurement process, and the measurement part 50 faces the GaN wafer 30 supported by the stage 2A. And a photodetector 52 for detecting the measurement light IL transmitted through the GaN wafer 30 and the transmission part 2T. Then, the measurement unit 50 measures the transmittance of the GaN wafer 30 based on the detection result of the photodetector 52. Therefore, it is possible to irradiate the GaN wafer 30 with the laser light L and measure the transmittance of the GaN wafer 30 with the single stage 2r. That is, it is not necessary to move the GaN wafer 30 during the measurement process. Therefore, the irradiation position of the laser light L with respect to the GaN wafer 30 is unlikely to shift between the first irradiation process and the second irradiation process.
  • the above embodiment describes an example of the laser processing apparatus according to the present disclosure. Therefore, the laser processing apparatus according to the present disclosure is not limited to the above embodiment, and various modifications can be applied. That is, the elements of the first example, the second example, and the respective modified examples can be arbitrarily applied to the laser processing apparatus according to the above embodiment.
  • the control unit 6 irradiates the laser light L inside the GaN wafer 30 while changing the irradiation condition under the control of the irradiation unit 45 before the first irradiation process, and also under the control of the measurement unit 50.
  • the control unit 6 determines, based on the relationship between the irradiation condition and the transmittance, by the irradiation condition that the transmittance of the GaN wafer 30 after the first irradiation process becomes the reference value.
  • the irradiation section 45 may be controlled so that the inside of the GaN wafer 30 is irradiated with the laser light L to form the plurality of modified spots 13.
  • the relationship between the irradiation condition of the laser light L and the transmittance of the GaN wafer 30 is acquired before the first irradiation process. Therefore, in the subsequent first irradiation process (and subsequent second irradiation process), laser processing can be performed under appropriate irradiation conditions.
  • the acquisition process another wafer under the same conditions as the GaN wafer 30 on which the first irradiation process or the like is actually processed is used, or the same as the GaN wafer 30 on which the first irradiation process or the like is actually processed.
  • the relationship between the irradiation condition and the transmittance can be obtained by using another wafer of a lot or by using an unused portion of the GaN wafer 30 on which processing such as the first irradiation processing is actually performed.
  • the irradiation condition is not limited to pulse energy and may be pulse pitch or the like.
  • control unit 6 it is not essential to continuously perform the second irradiation process after the measurement process.
  • the control unit 6 detects the optimum processing condition by executing the first irradiation process and the measurement process on the sample.
  • the sample is, for example, another wafer under the same conditions as the GaN wafer 30 on which the first irradiation process or the like is actually performed, or another wafer in the same lot as the GaN wafer 30 on which the first irradiation process or the like is actually performed. It is a wafer or an unused part of the GaN wafer 30 on which processing such as the first irradiation process is actually performed.
  • the optimum irradiation conditions (pulse energy and/or pulse pitch) are acquired by performing the first irradiation processing and the measurement processing prior to the actual processing, and the laser with appropriate energy is used.
  • a suitable semiconductor member can be obtained by processing.
  • the control unit 6 performs a determination process of determining whether or not the obtained transmittance of the GaN wafer 30 is within the desired transmittance range. As a result, if the transmittance obtained by the measurement process is within the desired transmittance range, it is determined that the GaN wafer 30 is a good product, and if it is not within the desired transmittance range, the GaN wafer 30 is a defective product. To determine. Then, when the control unit 6 determines whether the product is a good product or a defective product, the control unit 6 can further change the processing conditions for the GaN wafer 30 to be processed next based on the determination result.
  • the light source 51 and the photodetector 52 are arranged so as to be distributed on both sides of the stage 2A, and the measurement light IL output from the light source 51 and transmitted through the transmission part 2T is detected. It was configured to do.
  • the light source 51 and the photodetector 52 may be arranged on one side of the stage 2A (on the side supporting the GaN wafer 30).
  • the photodetector 52 is a measurement output from the light source 51, transmitted through the GaN wafer 30, and reflected on the back surface of the GaN wafer 30 (the surface opposite to the front surface 30a and facing the stage 2A).
  • the light IL can be detected.
  • the light source 51 and the photodetector 52 are arranged on one side of the stage 2A, and a mirror that reflects the measurement light IL to the surface of the stage 2A that supports the GaN wafer 30 is provided. You can make it.
  • the photodetector 52 detects the measurement light IL output from the light source 51, transmitted through the GaN wafer 30, reflected by the mirror, and transmitted through the GaN wafer 30 again. In this case, the signal light intensity can be increased to improve the SN ratio.
  • a laser processing method capable of obtaining a suitable semiconductor member and a semiconductor member manufacturing method.
  • 1A Laser processing device, 2... Stage, 2T... Transmission part, 6... Control part, 13... Modification spot, 15... Virtual surface, 30... GaN wafer (semiconductor object), 30a... Surface, 40... Semiconductor device ( Semiconductor member), 45... Irradiation part, 50... Measuring part, 51... Light source, 52... Photodetector, L... Laser light, R... Deposition region.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Plasma & Fusion (AREA)
  • Mechanical Engineering (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Manufacturing & Machinery (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Laser Beam Processing (AREA)
  • Mechanical Treatment Of Semiconductor (AREA)

Abstract

L'invention concerne un appareil d'usinage au laser comprenant une platine qui soutient un objet semi-conducteur contenant du gallium, une partie d'émission qui expose à une lumière laser l'objet semi-conducteur soutenu par la platine, une partie de mesure qui mesure la transmittance de l'objet semi-conducteur, et une unité de commande qui commande la partie d'émission et la partie de mesure. L'unité de commande effectue : un premier processus d'émission au cours duquel la lumière laser est émise pour former une pluralité de points de modification et des zones de dépôt contenant du gallium ayant été déposé dans la pluralité de points de modification le long d'un plan virtuel à l'intérieur de l'objet semi-conducteur tourné vers la surface ; un processus de mesure au cours duquel la transmittance de l'objet semi-conducteur est mesurée, suite au premier processus d'émission ; et un second processus d'émission au cours duquel, suite au processus de mesure, l'intérieur du semi-conducteur est exposé à une lumière laser provenant de la surface dans des conditions d'émission qui dépendent de la transmittance de l'objet semi-conducteur mesurée au cours du processus de mesure.
PCT/JP2019/049959 2018-12-21 2019-12-19 Appareil d'usinage au laser WO2020130110A1 (fr)

Applications Claiming Priority (2)

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JP2018-239496 2018-12-21
JP2018239496A JP7258542B2 (ja) 2018-12-21 2018-12-21 レーザ加工装置

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WO2020130110A1 true WO2020130110A1 (fr) 2020-06-25

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WO2023106017A1 (fr) * 2021-12-08 2023-06-15 株式会社デンソー Procédé de fabrication de tranche

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005098916A1 (fr) * 2004-03-30 2005-10-20 Hamamatsu Photonics K.K. Procede de traitement au laser et pucee semiconducteur
JP2007319881A (ja) * 2006-05-31 2007-12-13 Seiko Epson Corp 基体の製造方法、レーザ加工装置、表示装置、電気光学装置、電子機器
JP2014116361A (ja) * 2012-12-06 2014-06-26 Disco Abrasive Syst Ltd ウエーハのレーザー加工方法およびレーザー加工装置
JP2017183600A (ja) * 2016-03-31 2017-10-05 パナソニックＩｐマネジメント株式会社 スライス方法およびスライス装置

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005098916A1 (fr) * 2004-03-30 2005-10-20 Hamamatsu Photonics K.K. Procede de traitement au laser et pucee semiconducteur
JP2007319881A (ja) * 2006-05-31 2007-12-13 Seiko Epson Corp 基体の製造方法、レーザ加工装置、表示装置、電気光学装置、電子機器
JP2014116361A (ja) * 2012-12-06 2014-06-26 Disco Abrasive Syst Ltd ウエーハのレーザー加工方法およびレーザー加工装置
JP2017183600A (ja) * 2016-03-31 2017-10-05 パナソニックＩｐマネジメント株式会社 スライス方法およびスライス装置

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