WO2020071449A1 - 撮像装置、レーザ加工装置、及び、撮像方法 - Google Patents

撮像装置、レーザ加工装置、及び、撮像方法

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Publication number
WO2020071449A1
WO2020071449A1 PCT/JP2019/038993 JP2019038993W WO2020071449A1 WO 2020071449 A1 WO2020071449 A1 WO 2020071449A1 JP 2019038993 W JP2019038993 W JP 2019038993W WO 2020071449 A1 WO2020071449 A1 WO 2020071449A1
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WO
WIPO (PCT)
Prior art keywords
imaging
unit
line
laser
light
Prior art date
Application number
PCT/JP2019/038993
Other languages
English (en)
French (fr)
Japanese (ja)
Inventor
剛志 坂本
康孝 鈴木
いく 佐野
Original Assignee
浜松ホトニクス株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 浜松ホトニクス株式会社 filed Critical 浜松ホトニクス株式会社
Priority to KR1020217011484A priority Critical patent/KR20210066846A/ko
Priority to CN201980065099.4A priority patent/CN112770866B/zh
Publication of WO2020071449A1 publication Critical patent/WO2020071449A1/ja

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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
    • 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
    • B23K26/032—Observing, e.g. monitoring, the workpiece using optical means
    • 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
    • B23K26/04—Automatically aligning, aiming or focusing the laser beam, e.g. using the back-scattered light
    • B23K26/046—Automatically focusing the laser beam
    • 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
    • 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
    • B23K2101/00—Articles made by soldering, welding or cutting
    • B23K2101/36—Electric or electronic devices
    • B23K2101/40—Semiconductor devices

Definitions

  • One aspect of the present disclosure relates to an imaging device, a laser processing device, and an imaging method.
  • Patent Literature 1 includes an infrared camera, and observes a modified region formed inside a semiconductor substrate, processing damage formed on a functional element layer, and the like from the back side of the semiconductor substrate. Is possible.
  • the infrared camera captures an image of the wafer on the same cutting line as the processing position of the wafer by the processing optical system, so that the formation position of the modified region formed inside the wafer, processing damage, and the like can be determined in real time. Confirmation and measurement can be performed. However, it takes a certain amount of time to confirm and measure the reformed region and the like using an infrared camera or the like. Therefore, if the formation of the modified region and the confirmation of the modified region and the like are simultaneously performed as in the laser processing apparatus described in Patent Document 1, the speed at which the modified region is formed is limited. The efficiency may decrease.
  • an object of one aspect of the present disclosure to provide an imaging device, a laser processing device, and an imaging method that enable nondestructive confirmation while suppressing a decrease in processing efficiency.
  • An imaging device is an imaging device for imaging a modified region formed in an object by irradiation of laser light, and / or a crack extending from the modified region, A first imaging unit that captures an image of the object with transmitted light; and a first control unit that controls the first imaging unit.
  • the first control unit includes a modified region on the object along the first line. After the formation, at the timing when the alignment of the irradiation position of the laser beam with respect to the first line is performed, a modified region formed along the first line and / or a crack extending from the modified region is included.
  • a first imaging process for controlling the first imaging unit is performed so as to image the area.
  • the first control unit executes a first imaging process of imaging the modified region in the object and / or the region including the crack extending from the modified region using light transmitted through the object. . Therefore, an image of a modified region or the like (a modified region and / or a crack extending from the modified region (the same applies hereinafter)) can be obtained without destroying the target object, and these can be confirmed.
  • the first control unit may control the timing at which the laser light irradiation position is aligned with the first line after the modified region is formed on the object along the first line. , Execute the above-described first imaging process. Therefore, it is possible to confirm the modified region and the like without affecting the speed at which the modified region is formed. That is, according to this apparatus, it is possible to perform nondestructive confirmation while suppressing a decrease in processing efficiency.
  • the first control unit determines the irradiation position of the laser light after the modified region is formed on the target object along the second line that intersects the first line.
  • the first imaging unit is controlled so as to image a modified region formed along the second line and / or a region including a crack extending from the modified region. May be performed. In this case, it is possible to nondestructively check the modified regions and the like formed along the lines intersecting each other while suppressing the reduction in the processing efficiency.
  • a laser processing apparatus includes the above-described imaging apparatus, a laser irradiation unit for irradiating a target object with laser light, and a laser irradiation unit, and intersects a laser light incident surface on the target object. And a drive unit for moving the laser irradiation unit in the direction in which the laser irradiation unit moves.
  • the first imaging unit is attached to the drive unit together with the laser irradiation unit.
  • This device includes the above-mentioned imaging device. Therefore, according to this device, it is possible to perform nondestructive confirmation while suppressing a decrease in processing efficiency.
  • This device also includes a drive unit that moves the laser irradiation unit in a direction (incident direction) that intersects the laser light incident surface of the object. Then, the first imaging unit is attached to the drive unit together with the laser irradiation unit. Therefore, it is easy to share the position information in the incident direction in the formation of the modified region by the irradiation of the laser beam and the first imaging process.
  • a laser processing apparatus includes a second imaging unit that captures an image of an object using light transmitted through the object, and a second control unit that controls the laser irradiation unit and the second imaging unit.
  • the first imaging unit includes a first lens that transmits light transmitted through the object, and a first light detection unit that detects the light that has passed through the first lens.
  • an alignment process for controlling the laser irradiation unit and the second imaging unit may be performed so as to align the irradiation position of the laser light.
  • the second imaging unit for alignment of the irradiation position of the laser beam is separately used, so that an optical system suitable for each is used. Becomes possible.
  • the numerical aperture of the first lens may be larger than the numerical aperture of the second lens. In this case, it is possible to image the modified region or the like with a relatively large numerical aperture while ensuring alignment by observation with a relatively small numerical aperture.
  • the second control unit may execute the alignment processing after forming a plurality of rows of modified regions along the laser light incident surface of the target object.
  • performing alignment after forming a plurality of rows of modified regions is more efficient from both viewpoints of forming the modified regions and imaging the modified regions.
  • An imaging method is an imaging method for imaging a modified region formed on a target object by irradiation of a laser beam and / or a crack extending from the modified region, wherein the first line After the modified region is formed on the object along the line, and at the timing of performing the alignment of the irradiation position of the laser beam with the first line, the modified region formed along the first line, and / or A first imaging step of imaging an area including a crack extending from the modified area with light transmitted through the object.
  • the modified region of the object and / or the region including the crack extending from the modified region is imaged by light transmitted through the object. For this reason, it is possible to confirm the modified region and the like without destroying the target object.
  • the above-described imaging is performed at a timing when the alignment of the irradiation position of the laser beam with respect to the first line is performed. Therefore, it is possible to confirm the modified region and the like without affecting the speed at which the modified region is formed. That is, according to this method, nondestructive confirmation can be performed while suppressing a decrease in processing efficiency.
  • an imaging method after a modified region is formed in an object along a second line that intersects a first line, alignment of a laser light irradiation position with respect to the second line is performed.
  • a second imaging step is provided for imaging the modified region formed along the second line and / or the region including the crack extending from the modified region with light transmitted through the object. In this case, it is possible to nondestructively check the modified regions and the like formed along the lines intersecting each other while suppressing the reduction in the processing efficiency.
  • an imaging apparatus it is possible to provide an imaging apparatus, a laser processing apparatus, and an imaging method that enable nondestructive confirmation while suppressing a decrease in processing efficiency.
  • FIG. 2 is a configuration diagram of a laser irradiation unit shown in FIG. 1.
  • FIG. 2 is a configuration diagram of the inspection imaging unit shown in FIG. 1.
  • FIG. 2 is a configuration diagram of an alignment correction imaging unit shown in FIG. 1.
  • 6A and 6B are a cross-sectional view of a wafer for explaining the principle of imaging by the inspection imaging unit shown in FIG. 5 and images at various locations by the inspection imaging unit.
  • FIG. 6A and 6B are a cross-sectional view of a wafer for explaining the principle of imaging by the inspection imaging unit shown in FIG. 5 and images at various locations by the inspection imaging unit.
  • 3 is an SEM image of a modified region and a crack formed inside a semiconductor substrate.
  • 3 is an SEM image of a modified region and a crack formed inside a semiconductor substrate.
  • FIG. 6 is an optical path diagram for explaining an imaging principle of the inspection imaging unit shown in FIG. 5 and a schematic diagram showing an image at a focus by the inspection imaging unit.
  • FIG. 6 is an optical path diagram for explaining an imaging principle of the inspection imaging unit shown in FIG. 5 and a schematic diagram showing an image at a focus by the inspection imaging unit.
  • FIG. 6 is an optical path diagram for explaining an imaging principle of the inspection imaging unit shown in FIG. 5 and a schematic diagram showing an image at a focus by the inspection imaging unit.
  • FIG. 6 is a cross-sectional view of a wafer, an image of a cut surface of the wafer, and an image at each position of the inspection imaging unit for explaining the inspection principle by the inspection imaging unit shown in FIG. 5.
  • FIG. 6 is a cross-sectional view of a wafer, an image of a cut surface of the wafer, and an image at each position of the inspection imaging unit for explaining the inspection principle by the inspection imaging unit shown in FIG. 5.
  • 4 is a flowchart of a semiconductor device manufacturing method according to one embodiment.
  • FIG. 16 is a cross-sectional view of a part of the wafer in a grinding and cutting step of the semiconductor device manufacturing method shown in FIG. 15.
  • FIG. 16 is a cross-sectional view of a part of the wafer in a grinding and cutting step of the semiconductor device manufacturing method shown in FIG. 15.
  • FIG. 16 is a cross-sectional view of a part of the wafer in a grinding and cutting step of the semiconductor device manufacturing method shown in FIG. 15.
  • 4 is a flowchart illustrating a laser processing method and an imaging method according to an embodiment. It is a block diagram of the laser processing system provided with the imaging device of a modification.
  • the laser processing apparatus 1 includes a stage 2, a laser irradiation unit 3, a plurality of imaging units 4, 5, 6, a driving unit 7, and a control unit 8.
  • the laser processing apparatus 1 is an apparatus that forms a modified region 12 on an object 11 by irradiating the object 11 with a laser beam L.
  • the stage 2 supports the object 11 by, for example, adsorbing the film attached to the object 11.
  • the stage 2 is movable along each of the X direction and the Y direction, and is rotatable about an axis parallel to the Z direction as a center line.
  • the X direction and the Y direction are a first horizontal direction and a second horizontal direction perpendicular to each other, and the Z direction is a vertical direction.
  • the laser irradiation unit 3 condenses the laser light L having transparency to the object 11 and irradiates the object 11 with the laser light L.
  • the laser light L is particularly absorbed in a portion corresponding to the converging point C of the laser light L, and the laser light L is condensed inside the object 11.
  • the quality region 12 is formed.
  • the modified region 12 is a region in which the density, the refractive index, the mechanical strength, and other physical characteristics are different from those of the surrounding unmodified region.
  • Examples of the modified region 12 include a melt processing region, a crack region, a dielectric breakdown region, a refractive index change region, and the like.
  • the modified region 12 has a characteristic that a crack easily extends from the modified region 12 to the incident side of the laser beam L and the opposite side. Such characteristics of the modified region 12 are used for cutting the object 11.
  • a plurality of modified spots 12s are moved along the X direction by one. It is formed so as to line up in a row.
  • One modified spot 12s is formed by irradiation of one pulse of the laser beam L.
  • One row of the reforming regions 12 is a set of a plurality of reforming spots 12s arranged in one row. Adjacent modified spots 12s may be connected to each other or may be separated from each other depending on the relative moving speed of the focal point C with respect to the object 11 and the repetition frequency of the laser light L.
  • the imaging unit (first imaging unit) 4 captures an image of the object 11 supported by the stage 2 with light transmitted through the object 11 under the control of the control unit (first control unit) 8. More specifically, the imaging unit 4 images the modified region 12 formed in the object 11 and the tip of the crack extending from the modified region 12.
  • the imaging unit 4 and the control unit 8 that controls the imaging unit 4 function as the imaging device 10.
  • the imaging unit (second imaging unit) 5 and the imaging unit 6 cause the object 11 supported on the stage 2 to be controlled by light transmitted through the object 11 under the control of the control unit (second control unit) 8. Take an image.
  • the images obtained by the imaging units 5, 6 are used for alignment of the irradiation position of the laser light L, for example.
  • the drive unit 7 supports the laser irradiation unit 3 and the plurality of imaging units 4, 5, and 6.
  • the laser irradiation unit 3 is attached to the drive unit 7.
  • the imaging units 4, 5, and 6 are attached to the drive unit 7 together with the laser irradiation unit 3.
  • the drive unit 7 moves the laser irradiation unit 3 and the plurality of imaging units 4, 5, and 6 along the Z direction.
  • the Z direction is a direction that intersects the incident surface of the laser light L on the object 11 (for example, a back surface 21b described later).
  • the control unit 8 controls operations of the stage 2, the laser irradiation unit 3, the plurality of imaging units 4, 5, 6, and the driving unit 7.
  • the control unit 8 is configured as a computer device including a processor, a memory, a storage, a communication device, and the like.
  • the processor executes software (program) read into a memory or the like, and controls reading and writing of data in the memory and the storage, and communication by the communication device.
  • the object 11 of the present embodiment is a wafer 20, as shown in FIGS.
  • the wafer 20 includes a semiconductor substrate 21 and a functional element layer 22.
  • the semiconductor substrate 21 has a front surface 21a and a back surface 21b.
  • the semiconductor substrate 21 is, for example, a silicon substrate.
  • the functional element layer 22 is formed on a surface 21 a of the semiconductor substrate 21.
  • the functional element layer 22 includes a plurality of functional elements 22a two-dimensionally arranged along the surface 21a.
  • the functional element 22a 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 functional element 22a may have a three-dimensional configuration in which a plurality of layers are stacked.
  • the wafer 20 is cut for each functional element 22a along each of the plurality of lines 15.
  • the plurality of lines 15 pass between each of the plurality of functional elements 22a when viewed from the thickness direction of the wafer 20. More specifically, the line 15 passes through the center of the street area 23 (the center in the width direction) when viewed from the thickness direction of the wafer 20.
  • the street region 23 extends in the functional element layer 22 so as to pass between adjacent functional elements 22a.
  • the plurality of functional elements 22a are arranged in a matrix along the surface 21a, and the plurality of lines 15 are set in a grid. Note that the line 15 is a virtual line, but may be an actually drawn line.
  • the line 15 includes a plurality of first lines 15a and a plurality of second lines 15b intersecting (perpendicular to) the first lines 15a.
  • the first lines 15a are parallel to each other, and the second lines 15b are parallel to each other.
  • one pair of adjacent first lines 15a and one pair of adjacent second lines 15b define one rectangular parallelepiped functional element 22a.
  • the wafer 20 (object 11) includes a plurality of functional elements 22a defined by the first line 15a and the second line 15b when viewed from the Z direction.
  • the intersection of the first line 15a and the second line 15b defines a corner of the functional element 22a, and each of the first line 15a and the second line 15b defines a side of the functional element 22a.
  • the laser irradiation unit 3 includes a light source 31, a spatial light modulator 32, and a condenser lens 33.
  • the light source 31 outputs the laser light L by, for example, a pulse oscillation method.
  • the spatial light modulator 32 modulates the laser light L output from the light source 31.
  • the spatial light modulator 32 is, for example, a spatial light modulator (SLM: Spatial Light Modulator) of a reflection type liquid crystal (LCOS: Liquid Crystal On Silicon).
  • SLM Spatial Light Modulator
  • LCOS Liquid Crystal On Silicon
  • the laser irradiation unit 3 irradiates the wafer 20 with the laser beam L from the back surface 21b side of the semiconductor substrate 21 along each of the plurality of lines 15 so that the semiconductor light is irradiated along each of the plurality of lines 15.
  • Two rows of modified regions 12 a and 12 b are formed inside the substrate 21.
  • the modified region (first modified region) 12a is the modified region closest to the front surface 21a among the two rows of modified regions 12a and 12b.
  • the modified region (second modified region) 12b is the modified region closest to the modified region 12a and the modified region closest to the back surface 21b of the two rows of modified regions 12a and 12b.
  • the two rows of the modified regions 12a and 12b are adjacent to each other in the thickness direction (Z direction) of the wafer 20.
  • the two rows of the modified regions 12 a and 12 b are formed by moving the two condensing points C 1 and C 2 relative to the semiconductor substrate 21 along the line 15.
  • the laser light L is modulated by the spatial light modulator 32 so that, for example, the focal point C2 is located on the rear side in the traveling direction with respect to the focal point C1 and on the incident side of the laser light L.
  • the laser irradiation unit 3 moves the wafer 20 from the back surface 21b side of the semiconductor substrate 21 along each of the plurality of lines 15. Is irradiated with a laser beam L.
  • the semiconductor substrate 21 which is a single crystal silicon substrate having a thickness of 775 ⁇ m
  • two light-condensing points C1 and C2 are respectively aligned at positions of 54 ⁇ m and 128 ⁇ m from the surface 21a, and each of the plurality of lines 15
  • the wafer 20 is irradiated with the laser light L from the back surface 21b side of the semiconductor substrate 21 along the same.
  • the wavelength of the laser light L is 1099 nm
  • the pulse width is 700 ns
  • the repetition frequency is 120 kHz.
  • the output of the laser light L at the focal point C1 is 2.7 W
  • the output of the laser light L at the focal point C2 is 2.7 W
  • the moving speed is 800 mm / sec.
  • the formation of the two rows of the modified regions 12a and 12b and the crack 14 is performed in the following case. That is, in a later step, the semiconductor substrate 21 is thinned by grinding the back surface 21b of the semiconductor substrate 21 and the cracks 14 are exposed on the back surface 21b. This is the case when disconnecting to a device. [Configuration of imaging unit for inspection]
  • the imaging unit 4 has a light source 41, a mirror 42, an objective lens (first lens) 43, and a light detection unit (first light detection unit) 44.
  • the light source 41 outputs light I1 having transparency to the semiconductor substrate 21.
  • the light source 41 includes, for example, a halogen lamp and a filter, and outputs light I1 in the near infrared region.
  • the light I1 output from the light source 41 is reflected by the mirror 42, passes through the objective lens 43, and irradiates the wafer 20 from the back surface 21b side of the semiconductor substrate 21.
  • the stage 2 supports the wafer 20 on which the two rows of the modified regions 12a and 12b are formed as described above.
  • the objective lens 43 allows the light I1 reflected by the surface 21a of the semiconductor substrate 21 to pass. That is, the objective lens 43 transmits the light I1 that has propagated (transmitted) through the semiconductor substrate 21.
  • the numerical aperture (NA) of the objective lens 43 is 0.45 or more.
  • the objective lens 43 has a correction ring 43a.
  • the correction ring 43a corrects the aberration generated in the light I1 in the semiconductor substrate 21 by adjusting, for example, the distance between a plurality of lenses included in the objective lens 43.
  • the light detection unit 44 detects the light I1 that has passed through the objective lens 43 and the mirror 42.
  • the light detection unit 44 includes, for example, an InGaAs camera, and detects light I1 in the near infrared region.
  • the imaging unit 4 can capture an image of each of the two rows of the modified regions 12a and 12b and an end of each of the plurality of cracks 14a, 14b, 14c and 14d (details will be described later).
  • the crack 14a is a crack extending from the modified region 12a to the surface 21a.
  • the crack 14b is a crack extending from the modified region 12a to the back surface 21b.
  • the crack 14c is a crack extending from the modified region 12b to the surface 21a side.
  • the crack 14d is a crack extending from the modified region 12b to the back surface 21b.
  • the controller 8 causes the laser irradiation unit 3 to irradiate the laser beam L under the condition that the cracks 14 extending over the two rows of the modified regions 12a and 12b reach the surface 21a of the semiconductor substrate 21 (see FIG. 4). If the crack 14 does not reach the surface 21a due to, for example, the plurality of such cracks 14a, 14b, 14c, and 14d are formed. [Configuration of alignment correction imaging unit]
  • the imaging unit 5 includes a light source 51, a mirror 52, a lens (second lens) 53, and a light detection unit (second light detection unit) 54.
  • the light source 51 outputs light I2 having transparency to the semiconductor substrate 21.
  • the light source 51 includes, for example, a halogen lamp and a filter, and outputs light I2 in the near infrared region.
  • the light source 51 may be shared with the light source 41 of the imaging unit 4.
  • the light I2 output from the light source 51 is reflected by the mirror 52, passes through the lens 53, and irradiates the wafer 20 from the back surface 21b side of the semiconductor substrate 21.
  • the lens 53 allows the light I2 reflected by the surface 21a of the semiconductor substrate 21 to pass. That is, the lens 53 allows the light I2 transmitted through the semiconductor substrate 21 to pass.
  • the numerical aperture of the lens 53 is 0.3 or less. That is, the numerical aperture of the objective lens 43 of the imaging unit 4 is larger than the numerical aperture of the lens 53.
  • the light detector 54 detects the light I2 that has passed through the lens 53 and the mirror 52.
  • the light detection unit 55 includes, for example, an InGaAs camera, and detects light I2 in the near infrared region.
  • the imaging unit 5 irradiates the wafer 20 with light I2 from the back surface 21b side and detects the light I2 returning from the front surface 21a (functional element layer 22). Thereby, the functional element layer 22 is imaged.
  • the imaging unit 5 irradiates the wafer 20 with light from the back surface 21b side and also emits light I2 returning from the formation position of the modified regions 12a and 12b in the semiconductor substrate 21. Is detected, an image of a region including the modified regions 12a and 12b is obtained. These images are used for alignment of the irradiation position of the laser beam L.
  • the imaging unit 6 has the same configuration as the imaging unit 5 except that the lens 53 has a lower magnification (for example, 6 times in the imaging unit 5 and 1.5 times in the imaging unit 6). , As in the imaging unit 5. [Principle of imaging by inspection imaging unit]
  • the semiconductor substrate 21 in which the cracks 14 extending to the two rows of the modified regions 12a and 12b reach the front surface 21a is arranged from the back surface 21b side to the front surface.
  • the focal point F (the focal point of the objective lens 43) is moved toward the side 21a.
  • the focal point F is focused on the front end 14e of the crack 14 extending from the modified region 12b toward the rear surface 21b from the rear surface 21b side, the front end 14e can be confirmed (the right image in FIG. 7).
  • the focal point F is focused on the crack 14 itself and the tip 14e of the crack 14 reaching the surface 21a from the back surface 21b side, they cannot be confirmed (the left image in FIG. 7).
  • the focus F is focused on the front surface 21a of the semiconductor substrate 21 from the back surface 21b side, the functional element layer 22 can be confirmed.
  • the semiconductor substrate 21 in which the crack 14 extending over the two rows of the modified regions 12 a and 12 b does not reach the front surface 21 a is located on the back surface 21 b side. Is moved toward the surface 21a from the focal point F. In this case, even if the focal point F is focused on the front end 14e of the crack 14 extending from the modified region 12a to the front surface 21a from the rear surface 21b side, the front end 14e cannot be confirmed (the left image in FIG. 8).
  • the focal point F is focused on a region on the side opposite to the back surface 21b with respect to the front surface 21a (that is, a region on the functional element layer 22 side with respect to the front surface 21a) from the back surface 21b side, and is symmetric with respect to the front surface 21a.
  • the virtual focus Fv is located at the tip 14e, the tip 14e can be confirmed (the right image in FIG. 8). Note that the virtual focus Fv is a point symmetrical with respect to the focus F and the surface 21a in consideration of the refractive index of the semiconductor substrate 21.
  • 9 and 10 are SEM (Scanning Electron Microscope) images of the modified region 12 and the crack 14 formed inside the semiconductor substrate 21 which is a silicon substrate.
  • 9B is an enlarged image of the area A1 shown in FIG. 9A
  • FIG. 10A is an enlarged image of the area A2 shown in FIG. 9B
  • FIG. (b) is an enlarged image of the area A3 shown in (a) of FIG.
  • the width of the crack 14 is about 120 nm, which is smaller than the wavelength of the light I1 in the near infrared region (for example, 1.1 to 1.2 ⁇ m).
  • FIG. 11A when the focal point F is positioned in the air, the light I1 does not return, so that a dark image is obtained (the right image in FIG. 11A).
  • FIG. 11B when the focal point F is located inside the semiconductor substrate 21, the light I1 reflected on the surface 21a returns, so that a whitish image is obtained ((b) in FIG. 11). )).
  • FIG. 11C when the focal point F is focused on the modified region 12 from the back surface 21b side, the modified region 12 absorbs a part of the light I1 reflected by the front surface 21a and returned. Due to scattering or the like, an image in which the modified region 12 appears dark in a whitish background is obtained (the right image in FIG. 11C).
  • FIGS. 12A and 12B when the focal point F is focused on the tip 14e of the crack 14 from the back surface 21b side, for example, optical singularities (stress concentration, strain, A portion of the light I1 reflected and returned by the surface 21a is scattered, reflected, interfered with, absorbed, etc. by the light confinement generated near the tip 14e due to atomic density discontinuity, etc. An image in which the tip 14e is darkened is obtained (the right images in FIGS. 12A and 12B). As shown in FIG. 12C, when the focal point F is focused on the portion other than the vicinity of the tip 14e of the crack 14 from the back surface 21b side, at least a part of the light I1 reflected by the front surface 21a returns. A whitish image is obtained (right image in FIG. 12C). [Inspection principle by inspection imaging unit]
  • the control unit 8 irradiates the laser irradiation unit 3 with the laser beam L under the condition that the cracks 14 extending over the two rows of the modified regions 12a and 12b reach the surface 21a of the semiconductor substrate 21.
  • the state of the tip 14e of the crack 14 is as follows. That is, as shown in FIG. 13, the tip 14e of the crack 14 does not appear in the region between the modified region 12a and the surface 21a and in the region between the modified region 12a and the modified region 12b.
  • tip position The position of the tip 14e of the crack 14 extending from the modified region 12b toward the back surface 21b (hereinafter, simply referred to as “tip position”) is on the back surface 21b side with respect to the reference position P between the modified region 12b and the back surface 21b. To position.
  • the control unit 8 irradiates the laser irradiation unit 3 with the laser beam L under the condition that the cracks 14 extending over the two rows of the modified regions 12a and 12b reach the surface 21a of the semiconductor substrate 21. Therefore, if the crack 14 extending over the two rows of the modified regions 12a and 12b does not reach the surface 21a due to some problem, the state of the tip 14e of the crack 14 is as follows. That is, as shown in FIG. 14, in a region between the modified region 12a and the surface 21a, a tip 14e of a crack 14a extending from the modified region 12a toward the surface 21a appears.
  • a tip 14e of a crack 14b extending from the modified region 12a toward the back surface 21b and a tip 14e of a crack 14c extending from the modified region 12b toward the surface 21a are provided.
  • the tip position of the crack 14 extending from the modified region 12b toward the back surface 21b is located on the front surface 21a with respect to a reference position P between the modified region 12b and the back surface 21b.
  • the crack 14 extending over the two rows of the modified regions 12a and 12b is formed by the semiconductor. Whether or not the surface 21a of the substrate 21 has been reached can be evaluated.
  • a region between the modified region 12a and the surface 21a is defined as an inspection region R1, and whether or not the tip 14e of the crack 14a extending from the modified region 12a toward the surface 21a exists in the inspection region R1. Inspection.
  • a region between the modified region 12a and the modified region 12b is set as the inspection region R2, and whether or not the tip 14e of the crack 14b extending from the modified region 12a toward the back surface 21b exists in the inspection region R2.
  • the third inspection is an inspection as to whether or not the tip 14e of the crack 14c extending from the modified region 12b to the surface 21a side exists in the inspection region R2.
  • a region extending from the reference position P toward the back surface 21b but not reaching the back surface 21b is defined as an inspection region R3, and the tip position of the crack 14 extending from the modified region 12b toward the back surface 21b is located in the inspection region R3. It is an inspection of whether or not.
  • Each of the inspection region R1, the inspection region R2, and the inspection region R3 is based on the position where the two condensing points C1 and C2 are aligned with the semiconductor substrate 21 before forming the two rows of the modified regions 12a and 12b. Can be set. When the cracks 14 extending over the two rows of the modified regions 12a and 12b reach the front surface 21a of the semiconductor substrate 21, the tip positions of the cracks 14 extending from the modified region 12b to the back surface 21b are stable. R3 can be set based on the result of the test processing. Since the imaging unit 4 can image each of the two modified regions 12a and 12b as shown in FIGS.
  • Each of the inspection region R1, the inspection region R2, and the inspection region R3 may be set based on the respective positions of the two modified regions 12a and 12b.
  • the semiconductor device manufacturing method of the present embodiment will be described with reference to FIG. Note that the semiconductor device manufacturing method of the present embodiment includes a laser processing method performed in the laser processing apparatus 1.
  • the wafer 20 is prepared and placed on the stage 2 of the laser processing device 1. Subsequently, the laser processing apparatus 1 irradiates the wafer 20 with the laser beam L from the back surface 21b side of the semiconductor substrate 21 along each of the plurality of lines 15 so that the semiconductor substrate 21 Are formed in two rows (S01, first step). In this step, under the condition that the cracks 14 extending over the two rows of the modified regions 12a and 12b reach the front surface 21a of the semiconductor substrate 21, the laser processing device 1 The wafer 20 is irradiated with the laser beam L from the side 21b.
  • the laser processing apparatus 1 inspects whether or not the tip 14e of the crack 14b extending from the modified region 12a toward the back surface 21b exists in the inspection region R2 between the modified region 12a and the modified region 12b. (S02, 2nd process).
  • the laser processing apparatus 1 focuses on the inspection region R2 from the back surface 21b side and detects light I1 propagating (transmitting) through the semiconductor substrate 21 from the front surface 21a side to the back surface 21b side. Then, it is inspected whether the tip 14e of the crack 14b exists in the inspection region R2.
  • the laser processing device 1 performs the second inspection.
  • the objective lens 43 of the imaging unit 4 focuses the focal point F in the inspection region R2 from the back surface 21b side, and the light detection unit 44 of the imaging unit 4 moves the semiconductor substrate from the front surface 21a side to the back surface 21b side.
  • the light I1 propagating through (transmitting) the light 21 is detected.
  • the imaging unit 4 is moved along the Z direction by the drive unit 7, and the focal point F is relatively moved along the Z direction in the inspection area R2.
  • the light detection unit 44 acquires the image data at each position in the Z direction.
  • the control unit 8 checks whether or not the tip 14e of the crack 14b exists in the inspection region R2 based on the signal output from the light detection unit 44 (that is, the image data at each point in the Z direction). I do.
  • the control unit 8 evaluates the processing result in the step S01 based on the inspection result in the step S02 (S03, third step).
  • the control unit 8 evaluates that the crack 14 extending over the two rows of the modified regions 12a and 12b reaches the surface 21a of the semiconductor substrate 21.
  • the control unit 8 evaluates that the crack 14 extending over the two rows of the modified regions 12a and 12b has not reached the surface 21a of the semiconductor substrate 21.
  • the control unit 8 performs a pass process (S04).
  • the control unit 8 performs, as a pass process, a display indicating success on a display provided in the laser processing apparatus 1, a display of image data on the display, and a record of success on a storage unit included in the laser processing apparatus 1. (Storage as a log) and storage of image data by the storage unit.
  • the display provided in the laser processing apparatus 1 functions as a notification unit that notifies the operator of the success.
  • the control unit 8 performs a rejection process (S05).
  • the control unit 8 performs, as rejection processing, lighting of rejection by a lamp provided in the laser processing apparatus 1, display of rejection by a display provided in the laser processing apparatus 1, The recording of the rejection (storage as a log) by the storage unit provided is performed.
  • at least one of the lamp and the display included in the laser processing apparatus 1 functions as a notification unit that notifies the operator of the rejection.
  • the above steps S01 to S05 are the laser processing method performed in the laser processing apparatus 1.
  • step S04 When the pass process of step S04 is performed (that is, in step 03, it is evaluated that the crack 14 extending over the two rows of the modified regions 12a and 12b reaches the surface 21a of the semiconductor substrate 21), By grinding the back surface 21b of the semiconductor substrate 21, the cracks 14 extending over the two rows of the modified regions 12a and 12b are exposed on the back surface 21b, and the wafer 20 is formed along a plurality of lines 15 into a plurality of semiconductor devices. Cut (S06, 4th process).
  • the above steps S01 to S06 are the semiconductor device manufacturing methods including the laser processing method performed in the laser processing apparatus 1.
  • the rejection process of the step S05 that is, when it is evaluated in the step 03 that the crack 14 extending over the two rows of the modified regions 12a and 12b does not reach the surface 21a of the semiconductor substrate 21
  • Inspection and adjustment of the laser processing apparatus 1 laser processing (recovery processing) on the wafer 20 again, and the like are performed.
  • a grinding device 200 thins the semiconductor substrate 21 by grinding (polishing) the back surface 21 b of the semiconductor substrate 21, exposes the cracks 14 on the back surface 21 b, and The wafer 20 is cut into a plurality of semiconductor devices 20a along the line.
  • the grinding device 200 grinds the back surface 21b of the semiconductor substrate 21 to the reference position P for the fourth inspection.
  • the tip position of the crack 14 extending from the modified region 12b to the back surface 21b is determined at the reference position P With respect to the back surface 21b. Therefore, by grinding the back surface 21b of the semiconductor substrate 21 to the reference position P, the cracks 14 extending over the two rows of the modified regions 12a and 12b can be exposed on the back surface 21b.
  • the grinding end expected position is set as the reference position P, and the cracks 14 extending over the two rows of the modified regions 12a and 12b reach the surface 21a of the semiconductor substrate 21 and the reference position P, respectively, on each of the plurality of lines 15.
  • the wafer 20 is irradiated with the laser light L from the back surface 21b side of the semiconductor substrate 21 along the same.
  • the expanding apparatus 300 expands the expand tape 201 attached to the back surface 21b of the semiconductor substrate 21, thereby separating the plurality of semiconductor devices 20a from each other.
  • the expand tape 201 is, for example, a DAF (Die ⁇ Attach ⁇ Film) composed of a base 201a and an adhesive layer 201b.
  • the adhesive layer 201b disposed between the back surface 21b of the semiconductor substrate 21 and the base 201a is cut for each semiconductor device 20a.
  • the cut adhesive layer 201b is picked up together with the semiconductor device 20a.
  • the wafer 20 when inspecting whether or not the tip 14e of the crack 14b exists in a predetermined area, the wafer 20 is imaged.
  • the imaging of the wafer 20 is performed by the imaging device 10 including the imaging unit 4 and the control unit 8.
  • the wafer 20 is imaged with the execution of the second inspection.
  • the timing of the second inspection is not limited to this.
  • the timing of performing the second inspection is after forming the modified regions 12a and 12b along one or more first lines 15a, and the alignment of the irradiation position of the laser light L with respect to the first lines 15a is not performed.
  • the timing may be performed.
  • the second position is adjusted at the timing when the irradiation position of the laser beam L is aligned with the second line 15b.
  • the inspection may be further performed.
  • this case will be described in detail.
  • the laser processing method shown in FIG. 18 includes an imaging method. As shown in FIG. 18, here, first, in a state where the wafer 20 is mounted on the stage 2 of the laser processing apparatus 1, alignment of a processing start position is performed (S11). In this step, for example, alignment is performed by the imaging unit 5 imaging the wafer 20 under the control of the control unit 8. More specifically, in this step, the control unit 8 controls the imaging unit 5 to image the functional element layer 22.
  • the laser processing apparatus 1 (for example, the control unit 8) previously stores the size (chip size) of the functional element 22a, the work size (size of the processing range) on the wafer 20, and the reference image of the functional element layer 22. Initial information is registered. Then, the control unit 8 performs alignment of the irradiation position of the laser light L (the position of the laser irradiation unit 3 in the X direction and the Y direction) based on the image obtained by the imaging unit 5 and the initial information.
  • the control unit 8 performs alignment of the irradiation position of the laser light L (the position of the laser irradiation unit 3 in the X direction and the Y direction) based on the image obtained by the imaging unit 5 and the initial information.
  • the control unit 8 sets the processing height (position in the Z direction) of the laser irradiation unit 3 by controlling the drive unit 7 (S12). Subsequently, the control unit 8 starts forming the modified regions 12a and 12b (S13).
  • processing is performed from the first line 15a.
  • the laser processing apparatus 1 irradiates the wafer 20 with the laser beam L from the back surface 21b side of the semiconductor substrate 21 along one first line 15a, so that the laser processing device 1 moves along the first line 15a. Two rows of modified regions 12a and 12b are formed inside the semiconductor substrate 21.
  • the control unit 8 determines whether or not the position of the first line 15a is a preset alignment position (S14).
  • the alignment is a re-alignment for correcting a position shift occurring with respect to the alignment performed in step S11. This re-alignment may be performed every time the processing in one first line 15a is completed, but it is more efficient to perform the alignment after the plurality of first lines 15a are completed. That is, the alignment position may be set for each first line 15a, but it is efficient to set one alignment position for a plurality of first lines 15a.
  • step S13 if the position of the first line 15a, which has been processed in step S13, is not the alignment position, the process returns to step S13, and the modified regions 12a, 12b along another first line 15a are returned. Continue forming.
  • step S13 if the position of the first line 15a where the processing is completed in the step S13 is the alignment position, the alignment is performed again continuously. That is, in this case, the formation of the modified regions 12a and 12b is temporarily stopped, and the timing for performing the alignment is reached.
  • the control unit 8 controls the imaging unit 4 to image the wafer 20 (S15, first imaging step).
  • the control unit 8 moves the imaging unit 4 along the Z direction, so that the focus F is relatively moved inside the wafer 20 along the Z direction.
  • the imaging unit 4 performs imaging at each position in the Z direction and acquires an image.
  • the obtained image may include only the modified regions 12a and 12b, may include the modified regions 12a and 12b and the crack 14, or may include only the crack 14. is there.
  • the control unit 8 performs alignment of the irradiation position of the laser beam L with respect to the first line 15a.
  • the imaging unit 4 is controlled so as to image the modified regions 12a and 12b formed along the first line 15a and / or the region including the cracks 14 extending from the modified regions 12a and 12b at the timing.
  • a first imaging process (first imaging step) is performed.
  • the image obtained in this step is provided to the control unit 8. Therefore, the control unit 8 can execute the second inspection based on the supplied image data and based on the method and principle described above.
  • the control unit 8 executes an alignment process (S16).
  • An example of the alignment here is as follows. That is, the control unit 8 controls the imaging unit 5 to image the functional element layer 22 at the alignment correction position. The control unit 8 controls the imaging unit 5 to image an area including the modified areas 12a and 12b at the same position. Then, the control unit 8 detects a shift amount of the modified regions 12a and 12b with respect to a predetermined position (for example, the center position) of the street region 23 based on the two images. The control unit 8 performs the alignment of the irradiation position of the laser light L again based on the detected shift amount.
  • the control unit 8 controls the imaging unit 5 to image the functional element layer 22 at the alignment correction position. Then, the control unit 8 performs pattern matching between the image of the functional element layer 22 at the alignment correction position acquired before processing and the image of the functional element layer 22 acquired in this step, thereby obtaining a characteristic such as an alignment mark. The amount of deviation between points is detected. The control unit 8 adjusts the irradiation position of the laser light L based on the detected shift amount.
  • the control unit 8 determines whether or not the formation of the modified regions 12a and 12b along all the first lines 15a has been completed (S17). If the result of this determination is that formation of the modified regions 12a and 12b along all the first lines 15a has not been completed, the process returns to step S13, and the modified regions 12a and 12b along the remaining first lines 15a. Continue forming. On the other hand, as a result of this determination, when the formation of the modified regions 12a and 12b along all the first lines 15a has been completed, subsequently, the formation of the modified regions 12a and 12b along the second line 15b is continued. Start forming.
  • the formation of the modified regions 12a and 12b is temporarily stopped, the formation of the modified regions 12a and 12b along the first line 15a, and the formation of the modified regions 12a and 12b along the second line 15b. 12b is formed.
  • the laser processing apparatus 1 irradiates the wafer 20 with the laser beam L from the back surface 21b side of the semiconductor substrate 21 along one second line 15b, so that the laser processing device 1 moves along the second line 15b.
  • Two rows of modified regions 12a and 12b are formed inside the semiconductor substrate 21 (S18).
  • the control unit 8 determines whether the position of the second line 15b is a preset alignment position (S19).
  • the alignment is a re-alignment for correcting a position shift occurring with respect to the alignment performed in step S16. This re-alignment may be performed every time the processing in one second line 15b is completed, but it is more efficient to perform the alignment after the completion of a plurality of second lines 15b. That is, the alignment position here may be set for each second line 15b, but it is efficient to set one for a plurality of second lines 15b.
  • step S18 if the position of the second line 15b that has been processed in step S18 is not the alignment position, the process returns to step S18, and the modified regions 12a and 12b along another second line 15b are removed. Continue forming.
  • step S18 if the position of the second line 15b where the processing has been completed in step S18 is the alignment position, the alignment is performed again subsequently. That is, in this case, the formation of the modified regions 12a and 12b is temporarily stopped, and the timing for performing the alignment is reached.
  • the control unit 8 controls the imaging unit 4 to image the wafer 20 (S20, second imaging step).
  • the imaging mode is the same as in step S15.
  • the control unit 8 performs control at the timing when the irradiation position of the laser beam L is aligned with the second line 15b.
  • the second unit that controls the imaging unit 4 to image the modified region 12a, 12b formed along the second line 15b and / or the region including the crack 14 extending from the modified region 12a, 12b.
  • An imaging process (second imaging process) is performed.
  • the image obtained in this step is provided to the control unit 8. Therefore, the control unit 8 can execute the second inspection based on the supplied image data and based on the method and principle described above.
  • step S21 alignment is performed again as described above (S21).
  • the mode of alignment here is the same as in step S16.
  • the control unit 8 determines whether or not the formation of the modified regions 12a and 12b along all the second lines 15b has been completed (S22). If the result of this determination is that formation of the modified regions 12a and 12b along all the second lines 15b has not been completed, the process returns to step S18, and the modified regions 12a and 12b along the remaining second lines 15b. Continue forming. On the other hand, if the result of this determination is that the formation of the modified regions 12a and 12b along all the second lines 15b has been completed, the process is completed.
  • the location where the second inspection is performed may be at least one of the plurality of lines 15 set in a lattice shape. Can be sides.
  • the functional element 22a is defined by the first line 15a and the second line 15b when viewed from the Z direction. Therefore, the location where the second inspection is performed can be an area of a side corresponding to the first line 15a and / or the second line 15b of the functional element 22a when viewed from the Z direction.
  • the location where the second inspection is performed may be a location excluding a corner area that is the intersection of the first line 15a and the second line 15b in the functional element 22a when viewed from the Z direction.
  • the second inspection is illustrated as the inspection of the crack 14, but the first inspection, the third inspection, or the second inspection is not limited to the second inspection.
  • the fourth inspection may be performed.
  • the focus F is focused on the back surface 21b side of the semiconductor substrate 21 in the inspection region R2 between the modified region 12a and the modified region 12b, and the semiconductor substrate 21 is moved from the front surface 21a side to the back surface 21b side. Is detected.
  • the tip 14e of the crack 14b can be confirmed.
  • the tip 14e of the crack 14b exists in the inspection region R2
  • it is assumed that the crack 14 extending over the two rows of the modified regions 12a and 12b does not reach the surface 21a of the semiconductor substrate 21. Therefore, according to the above-described laser processing method, it can be confirmed whether or not the cracks 14 extending over the two rows of the modified regions 12a and 12b have reached the surface 21a of the semiconductor substrate 21.
  • the back surface 21b of the semiconductor substrate 21 is ground. Is not performed, it is possible to prevent a situation in which the wafer 20 cannot be reliably cut along each of the plurality of lines 15 after the grinding process.
  • the above-described imaging device 10 forms the modified regions 12a and 12b and / or the cracks 14 extending from the modified regions 12a and 12b formed on the object 11 (the semiconductor substrate 21 of the wafer 20) by the irradiation of the laser beam L. It is for imaging.
  • the imaging device 10 includes an imaging unit 4 that captures an image of the wafer 20 with light I1 that passes through at least the semiconductor substrate 21 of the wafer 20, and a control unit 8 that controls the imaging unit 4. After the modified regions 12a and 12b are formed in the semiconductor substrate 21 along the first line 15a, the control unit 8 controls the timing at which the irradiation position of the laser light L is aligned with the first line 15a.
  • First imaging that controls the imaging unit 4 so as to image an area including the modified regions 12a and 12b formed along the first line 15a and / or a crack 14 extending from the modified regions 12a and 12b. Execute the process.
  • the control unit 8 transmits light I ⁇ b> 1 transmitted through the semiconductor substrate 21 to the region including the modified regions 12 a and 12 b in the semiconductor substrate 21 and / or the crack 14 extending from the modified regions 12 a and 12 b.
  • a first imaging process for imaging is performed. For this reason, it is possible to acquire an image of the modified regions 12a and 12b and the like (the modified regions 12a and 12b and / or the cracks 14 extending from the modified regions 12a and 12b (the same applies hereinafter)) without destroying the wafer 20. These can be confirmed.
  • the control unit 8 controls the first line 15a at the irradiation position of the laser light L after the modified regions 12a and 12b are formed in the semiconductor substrate 21 along the first line 15a.
  • the above-described first imaging process is executed at the timing when the alignment with respect to is performed. Therefore, it is possible to confirm the modified regions 12a, 12b and the like without affecting the speed at which the modified regions 12a, 12b are formed. That is, according to the imaging device 10, nondestructive confirmation can be performed while suppressing a decrease in processing efficiency.
  • the control unit 8 irradiates the laser beam L after the modified regions 12a and 12b are formed on the semiconductor substrate 21 along the second line 15b intersecting the first line 15a.
  • the modified regions 12a and 12b formed along the second line 15b and / or the region including the crack 14 extending from the modified regions 12a and 12b are removed.
  • a second imaging process for controlling the imaging unit 4 is performed so as to capture an image. For this reason, it is possible to nondestructively check the modified regions 12a, 12b and the like formed along the line 15 intersecting each other while suppressing a decrease in processing efficiency.
  • the above-described laser processing apparatus 1 has the above-described imaging apparatus 10, a laser irradiation unit 3 for irradiating the wafer 20 with the laser light L, and the laser irradiation unit 3, and the laser irradiation unit 3 is mounted in the Z direction. And a drive unit 7 for moving.
  • the imaging unit 4 is attached to the drive unit 7 together with the laser irradiation unit 3.
  • the laser processing device 1 includes the above-described imaging device 10. Therefore, according to the laser processing apparatus 1, nondestructive confirmation can be performed while suppressing a reduction in processing efficiency. Further, the laser processing apparatus 1 includes a drive unit 7 for moving the laser irradiation unit 3 in the Z direction. Then, the imaging unit 4 is attached to the drive unit 7 together with the laser irradiation unit 3. Therefore, it is easy to share the position information in the Z direction between the formation of the modified regions 12a and 12b by the irradiation of the laser beam L and the first imaging process.
  • the laser processing apparatus 1 controls the imaging unit 5 that images the wafer 20 with the light I2 that passes through at least the semiconductor substrate 21 of the wafer 20, and the laser irradiation unit 3 and the imaging unit 5 (common to the imaging apparatus 10).
  • a control unit 8 The imaging unit 4 includes an objective lens 43 that passes the light I1 that has passed through the semiconductor substrate 21, and a light detection unit 44 that detects the light I1 that has passed through the objective lens 43.
  • the imaging unit 5 includes a lens 53 that passes the light I2 that has passed through the semiconductor substrate 21, and a light detection unit 54 that detects the light I2 that has passed through the lens 53.
  • control unit 8 executes an alignment process for controlling the laser irradiation unit 3 and the imaging unit 5 based on the detection result of the light detection unit 54 so as to align the irradiation position of the laser light L.
  • the imaging unit 5 for alignment of the irradiation position of the laser light L is separately used, so that an optical system suitable for each of them can be provided. It can be used.
  • the numerical aperture of the objective lens 43 is larger than the numerical aperture of the lens 53. In this case, it is possible to image the modified regions 12a, 12b and the like with a relatively large numerical aperture while ensuring alignment by observation with a relatively small numerical aperture.
  • control unit 8 may execute the alignment process after forming a plurality of rows of modified regions 12 a and 12 b along the laser light incident surface (the back surface 21 b) of the wafer 20. Good. As described above, it is more efficient to perform the alignment after forming the plurality of rows of the modified regions 12a and 12b from both viewpoints of forming the modified regions 12a and 12b and imaging the modified regions 12a and 12b. .
  • the above-described imaging method is an imaging method for imaging the modified regions 12a and 12b formed on the semiconductor substrate 21 by the irradiation of the laser light L and / or the cracks 14 extending from the modified regions 12a and 12b.
  • the first line 15a A first imaging step is provided for imaging the modified regions 12a and 12b formed along and / or the region including the cracks 14 extending from the modified regions 12a and 12b with the light I1 transmitted through the semiconductor substrate 21.
  • the region including the modified regions 12a and 12b and / or the crack 14 extending from the modified regions 12a and 12b in the semiconductor substrate 21 is imaged by the light I1 transmitted through the semiconductor substrate 21. Therefore, it is possible to check the modified regions 12a, 12b and the like without breaking the wafer 20.
  • the timing at which the irradiation position of the laser light L is aligned with the first line 15a In is performed. Therefore, it is possible to confirm the modified regions 12a, 12b and the like without affecting the speed at which the modified regions 12a, 12b are formed. That is, according to this method, nondestructive confirmation can be performed while suppressing a decrease in processing efficiency.
  • the above-described imaging method is performed after the modified regions 12a and 12b are formed on the semiconductor substrate 21 along the second line 15b intersecting the first line 15a, and the second position of the irradiation position of the laser light L
  • the modified region 12a, 12b formed along the second line 15b and / or the region including the crack 14 extending from the modified region 12a, 12b is transferred to the semiconductor substrate 21.
  • a second imaging step of imaging with the transmitted light I1 is provided. For this reason, it is possible to nondestructively check the modified regions 12a, 12b and the like formed along the line 15 intersecting each other while suppressing a decrease in processing efficiency.
  • the laser processing apparatus 1 forms two rows of the modified regions 12a and 12b inside the semiconductor substrate 21 along each of the plurality of lines 15;
  • One or three or more rows of the modified regions 12 may be formed inside the semiconductor substrate 21 along each of the lines 15.
  • the number of columns, the position, and the like of the modified region 12 formed for one line 15 may be appropriately determined in consideration of the thickness of the semiconductor substrate 21 in the wafer 20, the thickness of the semiconductor substrate 21 in the semiconductor device 20a, and the like.
  • the modified regions 12 in a plurality of rows may be formed by performing a relative movement of the focal point C of the laser beam L a plurality of times on one line 15.
  • the grinding device 200 may grind the back surface 21b of the semiconductor substrate 21 beyond the reference position P.
  • the expected grinding end position can be appropriately set according to whether or not the modified region 12 is left on the side surface (cut surface) of the semiconductor device 20a. If the semiconductor device 20a is, for example, a DRAM (Dynamic Random Access Memory), the modified region 12 may remain on the side surface of the semiconductor device 20a.
  • DRAM Dynamic Random Access Memory
  • the imaging device 10 may be configured separately from the laser processing device 1.
  • the imaging device 10 illustrated in FIG. 19 includes a stage 101, a driving unit 102, and a control unit (first control unit) 103 in addition to the imaging unit 4.
  • the stage 101 is configured in the same manner as the stage 2 described above, and supports the wafer 20 on which a plurality of rows of the modified regions 12 are formed.
  • the drive unit 102 supports the imaging unit 4 and moves the imaging unit 4 along the Z direction.
  • the control unit 103 has the same configuration as the control unit 8 described above.
  • a wafer 20 is transferred between the laser processing apparatus 1 and the imaging apparatus 10 by a transfer device such as a robot hand.
  • the irradiation conditions of the laser beam L when the wafer 20 is irradiated with the laser beam L from the back surface 21b side of the semiconductor substrate 21 along each of the plurality of lines 15 are not limited to those described above.
  • the irradiation condition of the laser beam L is such that a crack 14 extending over a plurality of rows of modified regions 12 (for example, two rows of modified regions 12a and 12b) is formed between the semiconductor substrate 21 and the functional element layer 22.
  • the condition leading to the interface may be used.
  • the irradiation condition of the laser beam L may be a condition in which the cracks 14 extending over the plurality of rows of the modified regions 12 reach the surface of the functional element layer 22 on the side opposite to the semiconductor substrate 21.
  • the irradiation condition of the laser light L may be a condition in which the cracks 14 extending over a plurality of rows of the modified regions 12 reach the vicinity of the surface 21 a in the semiconductor substrate 21.
  • the irradiation condition of the laser beam L may be any condition as long as the cracks 14 are formed over a plurality of rows of the modified regions 12. In any case, it can be confirmed whether or not the cracks 14 extending over the plurality of rows of the modified regions 12 extend sufficiently to the surface 21a side of the semiconductor substrate 21.
  • each material in the above-described embodiment is not limited to the above-described materials and shapes, and various materials and shapes can be applied.
  • each configuration in one embodiment or the modification described above can be arbitrarily applied to each configuration in another embodiment or the modification.

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PCT/JP2019/038993 2018-10-04 2019-10-02 撮像装置、レーザ加工装置、及び、撮像方法 WO2020071449A1 (ja)

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