Object machining method and method for manufacturing semiconductor device

Abstract

An object machining method according to the present invention includes a laser machining step for forming a modified region along an imaginary plane inside the object. The laser machining step includes a first laser machining step in which a laser beam is irradiated under a first machining condition along at least a first portion of the imaginary plane to form a modified region, and after the first laser machining step, a second laser machining step in which a laser beam is irradiated under a second machining condition along the imaginary plane to form a modified region. The first machining condition is a condition under which a plurality of cracks included in the modified region are intermittently connected, and the second machining condition is a condition under which a plurality of cracks included in the modified region formed by the first and second laser machining steps are connected to each other and extend across the entire area of ​​the imaginary plane after the second laser machining step.

Description

Method for processing object and method for manufacturing semiconductor device

[0001] The present disclosure relates to a method for processing an object and a method for manufacturing a semiconductor device.

[0002] A known object processing method for processing an object includes a laser processing step in which a modified region is formed along a virtual surface inside the object by irradiating the object with laser light (see, for example, Patent Document 1). After the laser processing step, a portion of the object is peeled off, with the modified region spanning the virtual surface as a boundary.

[0003] Japanese Patent Application Laid-Open No. 2022-002312

[0004] In the above-described techniques, when forming a modified region, there is a risk that a crack that does not follow the imaginary plane may be unintentionally formed in the object, and in this case, when the object is peeled after laser processing, the crack may propagate in a direction that does not follow the imaginary plane.

[0005] Therefore, an object of the present disclosure is to provide an object processing method and a semiconductor device manufacturing method that can suppress the formation of cracks that do not follow the imaginary plane.

[0006] The object processing method according to the present disclosure is [1] "an object processing method for processing an object, comprising a laser processing step of irradiating the object with laser light to form a modified region along an imaginary surface inside the object, the laser processing step including: a first laser processing step of irradiating the laser light under first processing conditions along at least a first portion of the imaginary surface to form the modified region; and a second laser processing step of irradiating the laser light under second processing conditions along the imaginary surface after the first laser processing step to form the modified region, wherein the first processing conditions are conditions under which a plurality of cracks included in the modified region are intermittently connected, and the second processing conditions are conditions under which a plurality of cracks included in the modified region formed by the first and second laser processing steps are connected to each other and extend across the entire area of ​​the imaginary surface after the second laser processing step."

[0007] In this object processing method, a first laser processing step is performed to form a plurality of intermittently connected cracks along at least a first portion of the imaginary surface, and a second laser processing step is performed to connect the plurality of cracks and extend them across the entire imaginary surface. In this case, the intermittently connected cracks can be favorably guided to extend across the entire imaginary surface. Therefore, compared to forming a crack that extends across the entire imaginary surface in a single laser processing step, it is possible to prevent the unintended formation of cracks in the object that do not follow the imaginary surface.

[0008] The object processing method according to the present disclosure may be the object processing method described in [1] above, [2] "wherein in the first and second laser processing steps, the laser light is irradiated along a processing line having a plurality of parallel lines arranged side by side on the imaginary surface to form the modified region, the first processing condition being a condition under which the processed state of the modified region in the first portion after the first laser processing step is a first slicing state, the second processing condition being a condition under which the processed state of the modified region over the entire imaginary surface after the second laser processing step is a second slicing state, the first slicing state being a state in which at least some of the multiple cracks included in the modified region are not connected to each other in a direction intersecting the processing direction, and the second slicing state being a state in which the multiple cracks included in the modified region are extended and connected to each other in the processing direction and a direction intersecting the processing direction." In this case, the formation and extension of the cracks described above by the laser processing in the first and second laser processing steps can be specifically realized.

[0009] The object processing method according to the present disclosure may be [3] "the object processing method described in the above [2], in which the first slicing state is a state in which at least some of the multiple cracks included in the modified region are not connected to each other in the processing progress direction and in a direction intersecting the processing progress direction." In this case, it is possible to reliably realize multiple intermittent cracks formed by the first laser processing step.

[0010] The object processing method according to the present disclosure may be [4] "the object processing method described in [2] or [3] above, wherein the modified region has a plurality of modified spot groups each consisting of two or more adjacent modified spots, and the first slicing state is a state in which, in a cross section intersecting the virtual surface of the object, a plurality of cracks extending from a plurality of the modified spots in the modified spot groups are connected to each other, and a crack extending from a modified spot included in one of the adjacent modified spot groups is not connected to a crack extending from a modified spot included in the other of the adjacent modified spot groups." In this case, in the second laser processing step, the plurality of cracks can be made to be more likely to connect and to extend across the entire virtual surface.

[0011] The object processing method according to the present disclosure may be the object processing method described in any one of [1] to [4] above, [5], wherein the object has a front surface and a back surface opposite the front surface, and includes, as viewed from a direction facing the front surface, a peripheral portion located on the periphery and a main portion located inside the peripheral portion, the imaginary surface having a first surface formed inside the object along the boundary between the peripheral portion and the main portion, and a second surface formed inside the peripheral portion near the back surface, and the first portion includes at least a portion connecting the first surface and the second surface. Cracks that do not follow the imaginary surface are likely to form from such a first portion. In this regard, in the present disclosure, multiple cracks that are intermittently connected along the first portion are formed, thereby favorably guiding the propagation of cracks along the first portion. In other words, it is possible to suppress the formation of cracks that do not follow the imaginary surface from the first portion.

[0012] The object processing method according to the present disclosure may be [6] "the object processing method according to any one of [1] to [5] above, wherein in the second laser processing step, the laser light is irradiated along a portion of the imaginary surface other than the first portion to form the modified region." In this case, by performing laser processing in the second laser processing step along a portion other than the first portion, cracks are connected along the first portion as well, so there is no need to perform laser processing again in the second laser processing step along the first portion, which reduces processing time and enables faster processing.

[0013] The object processing method according to the present disclosure may be [7] "the object processing method described in the above [5], including a peeling step of peeling off at least a part of the peripheral edge portion, with the modified region across the imaginary surface as a boundary, after the laser processing step." In this case, since it is possible to suppress the formation of cracks that do not follow the imaginary surface as described above, it is possible to peel off the peripheral edge portion with high precision.

[0014] The object processing method according to the present disclosure may be [8] "the object processing method described in the above [7], including, before the peeling step, a peripheral portion processing step of irradiating the laser light along radial lines extending radially from the inside to the outside of the peripheral portion to form the modified region." In this case, it is possible to reliably peel off the peripheral portion.

[0015] The object processing method according to the present disclosure may be [9] "the object processing method according to any one of [1] to [8] above, including a step of uniforming at least one of the reflectance and transmittance at the laser light incident surface of the object before the first laser processing step." It has been found that the laser processing in the first laser processing step is affected by the uniformity of the reflectance and transmittance at the laser light incident surface of the object. In this regard, the present disclosure makes it possible to uniformize at least one of the reflectance and transmittance at the laser light incident surface. Therefore, it is possible to reliably form a modified region in the object in which multiple cracks are intermittently connected by laser processing in the first laser processing step. Furthermore, in the first laser processing step, it is necessary to form the modified region in the first portion so that the cracks do not connect (so that the multiple cracks are intermittently connected). This embodiment is significant because the first laser processing step is easily affected by the condition of the laser light incident surface of the object due to, for example, weak laser light output.

[0016] The object processing method according to the present disclosure may be

[10] "the object processing method described in the above [9], in which, when the object has a film on the laser light incident surface side, the step of uniforming at least one of the reflectance and transmittance on the laser light incident surface includes irradiating the film with laser light or etching the film to remove the film." In this case, it is possible to more reliably realize the formation of a modified region in the object, in which a plurality of cracks are intermittently connected, by laser processing in the first laser processing step.

[0017] The object processing method according to the present disclosure may be

[11] "the object processing method according to any one of the above [1] to [9], wherein the object has a first substrate and a second substrate, a first device layer formed on a main surface of the first substrate, a second device layer formed on a main surface of the second substrate, and the first substrate and the second substrate are bonded via the first device layer and the second device layer." For such an object, the above-described effects of the present disclosure are particularly effective.

[0018] The object processing method according to the present disclosure may be the object processing method described in any one of [1] to

[11] above,

[12] in which "the object has a front surface and a back surface opposite the front surface, and is configured to include, as viewed from a direction facing the front surface, a peripheral portion located on the periphery and a main body portion located inside the peripheral portion, the imaginary surface having an imaginary main body surface formed along the back surface inside the main body portion, and an imaginary circumferential surface formed from the outer edge of the imaginary main body surface to the back surface and including a portion along the boundary between the peripheral portion and the main body portion, and the first portion includes at least a portion of the imaginary circumferential surface." In this case, a portion of the object can be peeled off, leaving the circumferential portion. Furthermore, in this case, although cracks that do not follow the imaginary surface are likely to form from the first portion, multiple cracks that are intermittently connected along the first portion are formed, which makes it possible to favorably guide the crack propagation along the first portion and suppress the formation of cracks that do not follow the imaginary surface from the first portion.

[0019] The object processing method according to the present disclosure may be the object processing method described in

[12] above,

[13] in which "the imaginary peripheral surface includes an imaginary intersection plane extending along the boundary between the peripheral edge portion and the main body portion so as to intersect with the back surface, and an imaginary connecting plane connecting the imaginary main body surface and the imaginary intersection plane, the first portion includes the imaginary connecting plane, the laser processing step further includes, before the first laser processing step, a cross-crack processing step of irradiating the laser light along the imaginary intersection plane to form the modified region, and the second processing condition is a condition in which multiple cracks included in the modified region formed by the cross-crack processing step and the first and second laser processing steps are connected to each other and extend across the entire area of ​​the imaginary surface after the second laser processing step." In this case, the above-mentioned effect of suppressing the formation of cracks that do not follow the imaginary surface from the first portion can be specifically achieved.

[0020] The object processing method according to the present disclosure may be the object processing method described in

[12] above,

[14] in which "the imaginary peripheral surface includes an imaginary intersection plane extending along the boundary between the peripheral edge portion and the main body portion so as to intersect with the back surface, and an imaginary connecting plane connecting the imaginary main body surface and the imaginary intersection plane, the first portion includes the imaginary connecting plane, the laser processing step further includes a main body crack processing step of irradiating the laser light along the imaginary main body surface to form the modified region before the first laser processing step, and the second processing condition is a condition in which multiple cracks included in the modified region formed by the main body crack processing step and the first and second laser processing steps are connected to each other and extend across the entire area of ​​the imaginary surface after the second laser processing step." In this case, the above-mentioned effect of suppressing the formation of cracks that do not follow the imaginary surface from the first portion can be specifically achieved.

[0021] The semiconductor device manufacturing method according to the present disclosure may be

[15] "a semiconductor device manufacturing method comprising: the laser processing step included in the object processing method according to any one of [1] to

[14] above; a peeling step of peeling the object along the imaginary plane after the laser processing step; and a cutting step of cutting the object into a plurality of chips after the peeling step." In this case, the object processing method is also carried out, thereby achieving the effect of suppressing the formation of cracks that do not follow the imaginary plane.

[0022] According to the present invention, it is possible to provide an object processing method and a semiconductor device manufacturing method that can suppress the formation of cracks that do not follow the imaginary plane.

[0023] FIG. 1 is a configuration diagram showing an object processing system according to an embodiment. FIG. 2 is a schematic diagram showing the configuration of the laser processing head of FIG. 1. FIG. 3(a) is a plan view showing the object of FIG. 1. FIG. 3(b) is a cross-sectional view taken along line A-A in FIG. 3(a). FIG. 4 is an enlarged view of a portion of a cross-section taken along line B-B in FIG. 3(b). FIG. 5(a) is a side cross-sectional view of a portion of an object for explaining an object processing method according to an embodiment. FIG. 5(b) is a side cross-sectional view showing a continuation of FIG. 5(a). FIG. 6(a) is a side cross-sectional view showing a continuation of FIG. 5(b). FIG. 6(b) is a side cross-sectional view showing a continuation of FIG. 6(a). FIG. 7 is a side cross-sectional view showing a continuation of FIG. 6(b). FIG. 8(a) is a side cross-sectional view of an object showing a virtual plane according to a first modified example. FIG. 8(b) is a side cross-sectional view of an object for explaining a first laser processing step according to the first modified example. FIG. 8(c) is a side cross-sectional view showing a continuation of FIG. 8(b). FIG. 9( a) is a side cross-sectional view of an object showing a virtual surface according to a second modified example. FIG. 9( b) is a side cross-sectional view of an object for explaining a first laser processing step according to the second modified example. FIG. 9( c) is a side cross-sectional view showing a continuation of FIG. 9( b). FIG. 10( a) is a side cross-sectional view of an object showing a virtual surface according to a third modified example. FIG. 10( b) is a side cross-sectional view of an object for explaining a first laser processing step according to the third modified example. FIG. 10( c) is a side cross-sectional view showing a continuation of FIG. 10( b). FIG. 11( a) is a side cross-sectional view of an object showing a virtual surface according to a fourth modified example. FIG. 11( b) is a side cross-sectional view of an object for explaining a first laser processing step according to the fourth modified example. FIG. 11( c) is a side cross-sectional view showing a continuation of FIG. 11( b). FIG. 12( a) is a side cross-sectional view of an object showing a virtual surface according to a fifth modified example. FIG. 12( b) is a side cross-sectional view of an object for explaining a first laser processing step according to the fifth modified example. Fig. 12(c) is a side cross-sectional view showing a continuation of Fig. 12(b). Fig. 13(a) is a side cross-sectional view of an object showing a set imaginary surface according to the sixth modified example. Fig. 13(b) is a side cross-sectional view of an object for explaining a first laser processing step according to the sixth modified example. Fig. 13(c) is a side cross-sectional view showing a continuation of Fig. 13(b). Fig. 14(a) is a side cross-sectional view of an object showing a imaginary surface according to the seventh modified example.FIG. 14(b) is a side cross-sectional view of an object for explaining a first laser processing step according to the seventh modified example. FIG. 14(c) is a side cross-sectional view showing a continuation of FIG. 14(b). FIG. 15(a) is a side cross-sectional view of an object showing a virtual surface according to the eighth modified example. FIG. 15(b) is a side cross-sectional view of an object for explaining a first laser processing step according to the eighth modified example. FIG. 15(c) is a side cross-sectional view showing a continuation of FIG. 15(b). FIG. 16 is a side cross-sectional view of an object showing a first slicing state according to the ninth modified example. FIG. 17 is a side view showing an object according to the tenth modified example. FIG. 18 is a plan view of an object for explaining a radial cut step. FIG. 19(a) is a side cross-sectional view of an object showing a virtual surface according to the eleventh modified example. FIG. 19(b) is a side cross-sectional view of an object for explaining a laser processing step according to the eleventh modified example. FIG. 19(c) is a side cross-sectional view of an object for showing a continuation of FIG. 19(b).

[0071] Figure 20(a) is a side cross-sectional view of the object showing a continuation of Figure 19(c). Figure 20(b) is a side cross-sectional view of the object showing a continuation of Figure 20(a). Figure 20(c) is a side cross-sectional view of the object showing a continuation of Figure 20(b). Figure 21 is an enlarged side cross-sectional view of the object for explaining the effect of the eleventh modified example. Figure 22(a) is a side cross-sectional view of the object for explaining the laser processing step according to the twelfth modified example. Figure 22(b) is a side cross-sectional view of the object showing a continuation of Figure 22(a). Figure 22(c) is a side cross-sectional view of the object showing a continuation of Figure 22(b). Figure 22(d) is a side cross-sectional view of the object showing a continuation of Figure 22(c). Figure 23(a) is a side cross-sectional view of the object for explaining the laser processing step according to the thirteenth modified example. Figure 23(b) is a side cross-sectional view of the object showing a continuation of Figure 23(a). Figure 23(c) is a side cross-sectional view of the object showing a continuation of Figure 23(b). Fig. 23(d) is a side cross-sectional view of the object showing a continuation of Fig. 23(c). Fig. 24(a) is a side cross-sectional view of the object for explaining the laser processing step according to the fourteenth modified example. Fig. 24(b) is a side cross-sectional view of the object showing a continuation of Fig. 24(a). Fig. 24(c) is a side cross-sectional view of the object showing a continuation of Fig. 24(b). Fig. 24(d) is a side cross-sectional view of the object showing a continuation of Fig. 24(c). Fig. 25(a) is a side cross-sectional view of the object for explaining the laser processing step according to the fifteenth modified example.Fig. 25(b) is a side cross-sectional view of the object showing a continuation of Fig. 25(a). Fig. 25(c) is a side cross-sectional view of the object showing a continuation of Fig. 25(b). Fig. 25(d) is a side cross-sectional view of the object showing a continuation of Fig. 25(c).

[0024] Hereinafter, the embodiments will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and duplicated explanations will be omitted.

[0025] As shown in FIG. 1 , the object processing system 101 according to the embodiment is a system for processing an object 11, and includes a laser processing device 1, an object transport mechanism 40, and a grinding device 60.

[0026] [Laser Processing Apparatus] The laser processing apparatus 1 is an apparatus that forms a modified region along a virtual surface inside the object 11 by aligning a focusing position (at least a part of the focusing region, the focusing point) on the object 11 and irradiating it with laser light. Before grinding by the grinding apparatus 60, the laser processing apparatus 1 irradiates the object 11 with laser light along a processing line to form one or more rows of modified regions on the virtual surface inside the object 11. The laser processing apparatus 1 is capable of performing trimming on the object 11. Trimming is a process for removing unnecessary portions of the object 11. In this embodiment, the X direction and Y direction are horizontal directions, and the Z direction is vertical directions.

[0027] The laser processing apparatus 1 includes a stage 2, a laser processing head 3, a Z-axis rail 22, a Y-axis rail 24, an imaging unit 25, a GUI 9, and a control unit 8. The stage 2 is a support unit that supports an object 11. The stage 2 is configured to be rotatable about an axis parallel to the Z direction as a center line. The object 11 is placed on the stage 2. The stage 2 is rotationally driven by the driving force of a known driving device such as a motor.

[0028] 1 and 2 , the laser processing head 3 irradiates the object 11 placed on the stage 2 with laser light L in the Z direction via a focusing unit 33, forming a modified region 12 inside the object 11. The laser processing head 3 is movable linearly in the Z direction along a Z-axis rail 22 by the driving force of a known driving device such as a motor. The laser processing head 3 is movable linearly in the Y direction along a Y-axis rail 24 by the driving force of a known driving device such as a motor. The laser processing head 3 constitutes an irradiation unit.

[0029] The laser processing head 3 focuses laser light L, which is transparent to the object 11, and irradiates the object 11. When the laser light L is focused inside the object 11, the laser light L is particularly absorbed in a portion corresponding to a focused region C of the laser light L, forming a modified region 12 inside the object 11. The focused region C is a region within a predetermined range from the position where the beam intensity of the laser light L is highest or the center of gravity of the beam intensity.

[0030] The modified region 12 is a region whose density, refractive index, mechanical strength, and other physical properties differ from those of the surrounding unmodified region. Examples of the modified region 12 include a melt-treated region, a crack region, a dielectric breakdown region, and a refractive index change region. The modified region 12 includes a plurality of modified spots 12s and a plurality of cracks extending from each of the plurality of modified spots 12s. One modified spot 12s is formed by irradiation with one pulse of laser light L.

[0031] The laser processing head 3 has a light source 31, a spatial light modulator 7, and a focusing unit 33. The light source 31 outputs laser light L, for example, by a pulse oscillation method. Note that the laser processing head 3 may not have the light source 31 and may be configured to introduce the laser light L from outside the laser processing head 3. The spatial light modulator 7 modulates the laser light L output from the light source 31. The focusing unit 33 focuses the laser light L modulated by the spatial light modulator 7 and output from the spatial light modulator 7 (i.e., the laser light that has passed through the spatial light modulator 7) toward the object 11. The focusing unit 33 includes a focusing lens.

[0032] When a signal indicating a modulation pattern is input from the control unit 8, the spatial light modulator 7 displays the modulation pattern in accordance with the signal. The modulation pattern is used to modulate the laser light L. When the laser light L is incident from the outside, reflected, and emitted to the outside while the modulation pattern is displayed on the spatial light modulator 7, the laser light L is modulated in accordance with the displayed modulation pattern. In this way, the spatial light modulator 7 can appropriately set the modulation pattern to be displayed to modulate the laser light L (e.g., modulation of the intensity, amplitude, phase, polarization, etc. of the laser light L). In the laser processing head 3, the laser light L output from the light source 31 is incident on the focusing unit 33 via the spatial light modulator 7 and focused within the target 11 by the focusing unit 33, thereby forming a modified region 12 in the target 11 in a portion corresponding to the focused region C.

[0033] Returning to FIG. 1 , the Z-axis rail 22 is a rail that extends along the Z direction. The Z-axis rail 22 is attached to the laser processing head 3 via an attachment portion 21. The Z-axis rail 22 moves the laser processing head 3 along the Z direction so that the focusing position of the laser light L moves along the Z direction. The Y-axis rail 24 is a rail that extends along the Y direction. The Y-axis rail 24 is attached to the Z-axis rail 22 via an attachment portion 23. The Y-axis rail 24 moves the laser processing head 3 along the Y direction so that the focusing position of the laser light L moves along the Y direction.

[0034] The imaging unit 25 images the object 11 from a direction along the incident direction of the laser light L. The imaging unit 25 includes an alignment camera AC and an imaging unit IR. The alignment camera AC and the imaging unit IR are attached to the mounting portion 21 together with the laser processing head 3. The alignment camera AC images, for example, a device pattern or the like using light that passes through the object 11. The image obtained thereby is used to align the irradiation position of the laser light L with respect to the object 11.

[0035] The control unit 8 is configured as a computer device including a processor, memory, storage, communication devices, etc. In the control unit 8, software (programs) loaded into the memory, etc. are executed by the processor, and the processor controls the reading and writing of data in the memory and storage, as well as communication by the communication devices. The control unit 8 controls each part of the laser processing apparatus 1 and realizes various functions.

[0036] The control unit 8 controls at least the stage 2, the laser processing head 3, the movement of the laser processing head 3 along the Z-axis rail 22, and the movement of the laser processing head 3 along the Y-axis rail 24. The control unit 8 controls the rotation of the stage 2, the irradiation of the laser light L from the laser processing head 3, and the movement of the focusing position of the laser light L. The control unit 8 can perform various controls based on rotation information (hereinafter also referred to as "θ information") regarding the amount of rotation of the stage 2. The θ information may be obtained from the drive amount of a drive device that rotates the stage 2, or may be obtained by a separate sensor or the like. The θ information can be obtained by various known methods.

[0037] The control unit 8 rotates the stage 2 while positioning the focusing position on the virtual surface M of the object 11, and controls the start and stop of irradiation of the laser light L by the laser processing head 3 based on the θ information under AF tracking control, thereby performing a trimming process to form a modified region 12 along the virtual surface M. The trimming process is a process performed by the control unit 8 to realize the trimming process.

[0038] The GUI 9 displays various types of information. The GUI 9 includes, for example, a touch panel display. Various settings related to processing conditions are input to the GUI 9 by a user's touch or other operation. The GUI 9 constitutes an input unit that accepts inputs from the user.

[0039] [Object Transfer Mechanism] The object transfer mechanism 40 is a mechanism that transfers the object 11 after being processed by the laser processing device 1 to the grinding device 60. The object transfer mechanism 40 includes an arm 41 that can hold the object 11, a slider 42 provided on the base end side of the arm 41, and a rail 43 for moving the slider 42 in the horizontal direction. The configuration of the object transfer mechanism 40 is not particularly limited, and various known configurations can be adopted as long as the object 11 can be transferred between the laser processing device 1 and the grinding device 60.

[0040] The object transport mechanism 40 includes a control unit 48 and a GUI 49. The control unit 48 is configured as a computer device including a processor, memory, storage, communication devices, etc. In the control unit 48, software loaded into the memory, etc. is executed by the processor, and the processor controls the reading and writing of data from and to the memory and storage, as well as communication via the communication devices. The control unit 48 controls each unit of the object transport mechanism 40 and realizes various functions. The GUI 49 displays various information. The GUI 49 includes, for example, a touch panel display. Various settings related to transport conditions are input into the GUI 49 by the user's touch or other operations.

[0041] [Grinding Device] The grinding device 60 is a device that grinds the object 11 after being processed by the laser processing device 1. The grinding device 60 is a device that grinds a removal area from the surface 11a of the object 11 to a planned grinding position (planned grinding depth). The grinding device 60 includes a grinding wheel 61 that is a grinding stone that can rotate at high speed, a base 62 that rotatably supports the grinding wheel, a vertical rail 63 for moving the base 62 in the vertical direction, a horizontal rail 64 for moving the base 62 in the horizontal direction, a thickness gauge 66 that measures the thickness of the object 11 to be ground, and a stage 67 on which the object 11 to be ground is placed. The stage 67 is configured to be rotatable about an axis parallel to the vertical direction as its center line.

[0042] The grinding device 60 includes a control unit 68 and a GUI 69. The control unit 68 is configured as a computer device including a processor, memory, storage, communication devices, etc. In the control unit 68, software loaded into the memory, etc. is executed by the processor, and the processor controls the reading and writing of data from and to the memory and storage, as well as communication via the communication devices. The control unit 68 controls each unit of the grinding device 60 and realizes various functions. The GUI 69 displays various information. The GUI 69 includes, for example, a touch panel display. Various settings related to grinding conditions are input into the GUI 69 by the user's touch or other operations.

[0043] Next, the main parts of this embodiment will be further described.

[0044] In the object processing method of this embodiment, a laser processing apparatus 1 irradiates an object 11 with laser light L to form a modified region 12 along a virtual surface inside the object 11 (laser processing step). As shown in FIGS. 3( a) and 3(b), the object 11 is, for example, a silicon wafer. The object 11 includes a front surface 11a, which is a first main surface, and a back surface 11b, which is a second main surface opposite the front surface 11a. A device layer including multiple functional elements is formed on the back surface 11b of the object 11. The object 11 is supported on the stage 2 so that the front surface 11a faces the laser processing head 3 (i.e., the front surface 11a is the laser light incident surface, and the back surface 11b faces the stage 2).

[0045] The object 11 includes a main body portion R, which is the effective area, and a peripheral edge portion E, which is the removal area. The main body portion R is a circular portion including the center of the object 11 when viewed from the Z direction, which is the direction facing the surface 11a (thickness direction of the object 11). The peripheral edge portion E is a region of the object 11 located outside the main body portion R. When viewed from the Z direction, the peripheral edge portion E is a portion located on the periphery of the object 11, and in this case, is the outer edge portion of the object 11 other than the main body portion R. The peripheral edge portion E is an annular portion surrounding the main body portion R. The peripheral edge portion E includes a bevel portion on the outer edge of the object 11.

[0046] A virtual surface M is set on the object 11 as a planned peeling surface. The virtual surface M is a surface on which the modified region 12 is planned to be formed. The virtual surface M is a virtual region. The virtual surface M is not limited to a flat surface, but may be a curved surface or a three-dimensional surface. The virtual surface M can be set by the control unit 8. The virtual surface M may be specified by coordinates. The virtual surface M has a first surface M3 formed inside the object 11 along the boundary between the peripheral edge portion E and the main body portion R, and a second surface M5 formed inside the peripheral edge portion E near the back surface 11b, inclined radially inward with respect to the Z direction as it approaches the front surface 11a. The second surface M5 is an annular surface and a plane parallel to the XY plane.

[0047] As shown in FIG. 4 , a processing line 5 having multiple parallel lines 5 a arranged side by side on a virtual plane M is set on the object 11. The processing line 5 is a virtual line. The multiple parallel lines 5 a are set parallel to the XY plane. The multiple parallel lines 5 a extend in annular shapes with different diameters. The extension direction of the parallel lines 5 a corresponds to the processing progress direction, which is the direction in which the laser light L travels (scanning direction). The direction in which the parallel lines 5 a are arranged corresponds to the index direction. The index direction is a direction perpendicular to the extension direction of the parallel lines 5 a when viewed from the laser light incident surface. The index direction is, for example, the direction in which the laser processing head 3 is translated relative to the stage 2 when moving the focusing position of the laser light L. The processing line 5 can be set by the control unit 8. The processing line 5 may be specified by coordinates.

[0048] In the laser processing step, as shown in Figures 5(a) and 5(b), laser light L is irradiated along first portions M8a and M8b of the virtual surface M under first processing conditions to form a modified region 12a (first laser processing step).

[0049] The first portions M8a and M8b are portions on the imaginary plane M that connect the first surface M3 and the second surface M5. The first portions M8a and M8b are bent portions on the imaginary plane M. The first portions M8a and M8b are surfaces that bend in multiple stages. The first portion M8a is an annular surface when viewed from the Z direction. The first portion M8a is an inclined surface that slopes toward the front surface 11a at a first angle with respect to the horizontal plane as it moves radially inward. When viewed in a cross section that includes the central axis of the object 11 and is along the Z direction (hereinafter referred to as a "cross section along the Z direction"), the first portion M8a extends linearly. The radially inner side of the first portion M8a is connected to the end of the first surface M3 on the back surface 11b side.

[0050] The first portion M8b is an annular surface when viewed from the Z direction. The first portion M8b is an inclined surface that inclines toward the front surface 11a at a second angle, which is smaller than the first angle, relative to the horizontal plane as it moves radially inward. In a cross-sectional view along the Z direction, the first portion M8b extends linearly. The radially inner side of the first portion M8b is connected to the end of the first portion 8a on the back surface 11b side. The radially outer side of the first portion M8b is connected to the radially inner end of the second surface M5.

[0051] Specifically, in the first laser processing step, the laser processing head 3 irradiates the target object 11 with laser light L under first processing conditions, and focuses the laser light L on processing lines 5 set in first portions M8a and M8b on the virtual surface M inside the target object 11. At the same time, while rotating the stage 2 so that the focusing position of the laser light L moves along the processing line 5, AF tracking control is performed to cause the focusing position to follow the displacement of the surface 11a, which is the laser light incident surface. This laser processing is repeatedly performed on all processing lines 5 on the first portions M8a and M8b. This forms modified regions 12a along the first portions M8a and M8b.

[0052] The first processing condition is a condition under which the multiple cracks contained in the modified region 12a are intermittently connected. The first processing condition is a condition under which the processed state of the modified region 12a of the first portions M8a and M8b after the first laser processing step is a first slicing state. The first slicing state is a slicing stealth state in which at least some of the multiple cracks contained in the modified region 12a are not connected to each other in both the processing progress direction and the index direction (a direction intersecting the processing progress direction). The first slicing state may also be a slicing half-cut state in which at least some of the multiple cracks contained in the modified region 12a are not connected to each other in the index direction. That is, in the first laser processing step, a modified region 12a (here, the modified region 12a in the first slicing state) in which the multiple cracks contained therein are intermittently connected is formed along the first portions M8a and M8b of the virtual plane M. The laser processing in the first laser processing step is also referred to as dot line processing.

[0053] Next, in the laser processing step, as shown in Figures 5(a) and 6(a), after the first laser processing step, laser light L is irradiated along the first surface M3 and the second surface M5 of the virtual surface M under second processing conditions to form the modified region 12b (second laser processing step).

[0054] Specifically, in the second laser processing step, the laser processing head 3 irradiates the target object 11 with laser light L under second processing conditions, and focuses the laser light L on processing lines 5 set on the first surface M3 and the second surface M5, which are portions of the imaginary surface M inside the target object 11 other than the first portions M8a and M8b. At the same time, while rotating the stage 2 so that the focusing position of the laser light L moves along the processing line 5, AF tracking control is performed to cause the focusing position to follow the displacement of the surface 11a, which is the laser light incident surface. This laser processing is repeatedly performed on all processing lines 5 on the first surface M3 and the second surface M5. This forms modified regions 12b along the first surface M3 and the second surface M5.

[0055] The second processing condition is a condition under which the multiple cracks contained in the modified regions 12a, 12b formed by the first laser processing step and the second laser processing step connect to each other and extend across the entire area of ​​the virtual surface M after the second laser processing step. The second processing condition is a condition under which the processed state of the modified region 12 across the entire area of ​​the virtual surface M after the second laser processing step becomes a second slicing state. The second slicing state is a slicing full-cut state in which the multiple cracks contained in the modified region 12 extend to each other in the processing progress direction and in a direction intersecting the processing progress direction. That is, in the second laser processing step, the modified region 12b in the second slicing state is formed along the first surface M3 and the second surface M5, and the modified region 12a in the first slicing state already formed in the first laser processing step changes into the modified region 12c in the second slicing state as the modified region 12b is formed.

[0056] The slicing stealth (SST) state is a state in which cracks do not extend or are not connected from the multiple modified spots (dents) 12s included in the modified region 12. The slicing stealth state is a state in which only the modified spots 12s can be observed by the imaging unit 25.

[0057] The slicing half-cut (SHC) state is a state in which cracks extending from multiple modified spots 12s included in the modified region 12 extend in a direction along the parallel lines 5a (processing progression direction). The slicing full-cut (SFC) state is a state in which cracks extending from multiple modified spots 12s included in the modified region 12 extend in a direction along the multiple parallel lines 5a and in a direction intersecting the parallel lines 5a and connect to each other. The slicing full-cut state is a state in which cracks extending from the modified spots 12s are connected across multiple parallel lines 5a. Since the slicing full-cut state is a state that occurs due to the connection of cracks that cross multiple parallel lines 5a, it cannot occur when the modified region 12 is formed by irradiating laser light L along a single parallel line 5a. In order to generate a slicing full cut state, when laser light L is irradiated along one parallel line 5a to form a modified region 12, the processing state is a slicing half cut state or a slicing stealth state.

[0058] 6(b), after the second laser processing step, external stress is applied to the object 11, and a portion of the peripheral edge E is peeled off along the modified region 12 across the virtual plane M (peeling step). Next, based on the transport conditions and the like input via the GUI 49, the object 11 is transported from the laser processing device 1 to the grinding device 60 by the object transport mechanism 40. Based on the grinding conditions and the like input via the GUI 69, the grinding device 60 performs a grinding step (removal step). That is, as shown in FIG. 7, the removal region from the surface 11a of the object 11 after the peeling step to the planned grinding depth is ground and removed using a polishing wheel 61. As a result of the above, a semiconductor device 11K is obtained (manufactured). Note that, between the peeling step and the removal step, a planarization process using laser processing or etching may be performed.

[0059] As described above, in the object processing method of this embodiment, a first laser processing step forms a plurality of cracks that are intermittently connected along the first portions M8a, M8b of the imaginary surface M, and a subsequent second laser processing step connects the plurality of cracks and extends them across the entire imaginary surface M. In this case, the intermittently connected plurality of cracks can suitably guide the cracks to extend across the entire imaginary surface M. Therefore, compared to forming a crack that extends across the entire imaginary surface M in a single laser processing step, it is possible to prevent cracks that do not extend along the imaginary surface M (initial cracks that extend in a direction other than along the imaginary surface M) from being unintentionally formed in the object 11.

[0060] In the object processing method of this embodiment, the first processing condition is a condition under which the processed state of the modified region 12a of the first portions M8a, M8b after the first laser processing step is a first slicing state, and the second processing condition is a condition under which the processed state of the modified region 12 over the entire imaginary surface M after the second laser processing step is a second slicing state. In this case, the formation and propagation of the above-mentioned cracks by the laser processing in the first and second laser processing steps can be specifically realized.

[0061] In the object processing method of this embodiment, the first slicing state is a slicing stealth state, which can reliably realize the formation of a plurality of intermittent cracks by the first laser processing step.

[0062] In the object processing method of this embodiment, the imaginary surface M has a first surface M3 along the boundary between the peripheral edge portion E and the main body portion R and a second surface M5 formed near the back surface 11b of the peripheral edge portion E. The first portions M8a and M8b constitute portions connecting the first surface M3 and the second surface M5. Cracks that do not follow the imaginary surface M are likely to form from such first portions M8a and M8b. In this regard, in this embodiment, multiple cracks that are intermittently connected along the first portions M8a and M8b are formed before the crack propagates across the entire imaginary surface M, thereby favorably guiding the crack to propagate along the first portions M8a and M8b. In other words, it is possible to suppress the formation of cracks that do not follow the imaginary surface M from the first portions.

[0063] In the object processing method of this embodiment, in the second laser processing step, laser light L is irradiated along portions of the imaginary plane M other than the first portions M8a, M8b to form modified region 12b. In this case, by performing laser processing in the second laser processing step along portions other than the first portions M8a, M8b, cracks are connected along the first portions M8a, M8b as well, so there is no need to perform laser processing again in the second laser processing step along the first portions M8a, M8b, which reduces the processing time and enables faster processing.

[0064] The object processing method of this embodiment includes, after the second laser processing step, a peeling step of peeling off the peripheral portion E at the boundary of the modified region 12 that spans the imaginary surface M. In this embodiment, as described above, the formation of cracks that do not follow the imaginary surface M can be suppressed, making it possible to peel off the peripheral portion E with high precision.

[0065] In this embodiment, the processed state of the modified region 12 formed at the connection portion between the first portion M8a and the first surface M3 of the imaginary surface M may be a slicing stealth state. In this embodiment, the processed state of the modified region 12 formed at the connection portion between the first portion M8b and the second surface M5 of the imaginary surface M may be a slicing stealth state. In this case, it is possible to further suppress the formation of cracks that do not follow the imaginary surface M.

[0066] In this embodiment, the second surface M5 formed near the back surface 11b of the object 11 is preferably closer to the object 11, and may be set so that at least a portion of the second surface M5 overlaps the back surface 11b. In this case, the object 11 can be made even thinner by the subsequent grinding process.

[0067] However, because the first slicing state is a relatively severe processing state, it has been found that the laser processing in the first laser processing step for forming the modified region 12a in the first slicing state is significantly affected by the uniformity of the reflectance and transmittance on the laser light incident surface of the object 11 (particularly the adverse effect of non-uniformity). Therefore, the object processing method of this embodiment may include a homogenization step for homogenizing at least one of the reflectance and transmittance on the laser light incident surface of the object 11 before the first laser processing step. In particular, if the object 11 has a film on the laser light incident surface side, the homogenization step may involve irradiating or etching the film with laser light to remove the film. This prevents the reflectance and transmittance on the laser light incident surface from becoming non-uniform, and enables the modified region 12a in the first slicing state (i.e., the modified region 12a containing multiple cracks that are intermittently connected) to be reliably formed in the object 11 by the laser processing in the first laser processing step. Furthermore, in the first laser processing step, it is necessary to form the modified region 12 in the first portions M8a, M8b so that the cracks are not connected (so that multiple cracks are intermittently connected). In such a first laser processing step, the output of the laser light L is weak, for example, and therefore the modified region 12 is easily affected by the state of the laser light incident surface of the object 11, and therefore the significance of this embodiment is great.

[0068] In this embodiment, after the peeling step, a cutting step may be performed to cut the object 11 (semiconductor device 11K) into multiple chips. A method including the laser processing step, the peeling step, and the cutting step constitutes a semiconductor device manufacturing method according to this embodiment. Note that any method, such as laser dicing, blade dicing, or plasma dicing, may be used to cut the object 11 in the cutting step. The semiconductor device manufacturing method according to this embodiment also employs the object processing method, thereby achieving the effect of preventing cracks from unintentionally forming in the object 11 that do not follow the imaginary plane M. Furthermore, multiple chips (semiconductor devices) can be obtained efficiently.

[0069] [Modifications] As described above, one aspect of the present disclosure is not limited to the above embodiment.

[0070] In the above embodiment, the imaginary surface M, the first laser processing step, and the second laser processing step are not particularly limited, and various aspects can be adopted, as exemplified below.

[0071] 8(a), 8(b), and 8(c) are cross-sectional views of the object 11 illustrating laser processing along a virtual plane M according to a first modified example. As shown in FIG. 8(a), the virtual plane M according to the first modified example includes a first surface M13 extending straight in the Z direction, the second surface M5 described above, and a first portion M18 connecting the first surface M13 and the second surface M5. The first portion M18 is an annular surface when viewed from the Z direction. The first portion M18 is an inclined surface that slopes toward the front surface 11a relative to the horizontal plane as it extends radially inward. The radially inner side of the first portion M18 is connected to the end of the first surface M13 on the back surface 11b side. The radially outer side of the first portion M18 is connected to the radially inner end of the second surface M5.

[0072] As shown in FIG. 8( b), when processing an object 11 having a virtual surface M according to the first modification, in the first laser processing step, laser light L is irradiated along the first portion 18 under first processing conditions to form a modified region 12a in the first slicing state. As shown in FIG. 8( c), in the second laser processing step following the first laser processing step, laser light L is irradiated along the first surface M13 and the second surface M5 of the virtual surface M under second processing conditions to form a modified region 12b in the second slicing state. As a result, the modified region 12a in the first slicing state, which has already been formed in the first laser processing step, undergoes crack propagation as the modified region 12b is formed, transforming into a modified region 12c in the second slicing state. This processing method also achieves the above-described effects.

[0073] 9(a), 9(b), and 9(c) are cross-sectional views of the object 11 illustrating laser processing along a virtual plane M according to the second modified example. As shown in Fig. 9(a), the virtual plane M according to the second modified example differs from the virtual plane M according to the first modified example (see Fig. 8(a)) in that it includes a first surface M23 instead of the first surface M13. The first surface M23 is a surface shaped to correspond to the peripheral surface of a truncated cone, and is an inclined surface that slopes radially inward with respect to the Z direction as it approaches the surface 11a.

[0074] As shown in FIG. 9( b), when processing an object 11 having a virtual surface M according to the second modification, in the first laser processing step, laser light L is irradiated along a first portion M18 of the virtual surface M under first processing conditions to form a modified region 12a in a first slicing state. As shown in FIG. 9( c), in the second laser processing step following the first laser processing step, laser light L is irradiated along a first surface M23 and a second surface M5 under second processing conditions to form a modified region 12b in a second slicing state. As a result, the modified region 12a in the first slicing state, which has already been formed in the first laser processing step, undergoes crack propagation as the modified region 12b is formed, transforming into a modified region 12c in a second slicing state. This processing method also achieves the above-described effects.

[0075] 10(a), 10(b), and 10(c) are cross-sectional views of the object 11 illustrating laser processing along a virtual plane M according to a third modified example. As shown in FIG. 10(a), the virtual plane M according to the third modified example differs from the virtual plane M according to the above embodiment (see FIG. 5(a)) in that it includes first portions M28a and M28b instead of the first portions M8a and M8b. In a cross-sectional view along the Z direction, the extension length of the first portion 28a is longer than the extension length of the first portion 28b. In other respects, the first portions M28a and M28b are configured similarly to the first portions M8a and M8b.

[0076] As shown in FIG. 10( b), when processing an object 11 having a virtual surface M according to the third modification, in the first laser processing step, laser light L is irradiated under first processing conditions along first portions M28a, 28b of the virtual surface M to form a modified region 12a in a first slicing state. As shown in FIG. 10( c), in the second laser processing step following the first laser processing step, laser light L is irradiated under second processing conditions along first surface M3 and second surface M5 to form a modified region 12b in a second slicing state. As a result, the modified region 12a in the first slicing state, which has already been formed in the first laser processing step, undergoes crack propagation as the modified region 12b is formed, transforming into a modified region 12c in a second slicing state. This processing method also achieves the above-described effects.

[0077] 11(a), 11(b), and 11(c) are cross-sectional views of the object 11 illustrating laser processing along a virtual plane M according to a fourth modified example. As shown in FIG. 11(a), the virtual plane M according to the fourth modified example differs from the virtual plane M according to the above embodiment (see FIG. 5(a)) in that it includes first portions M38a and M38b instead of the first portions M8a and M8b. In a cross-sectional view along the Z direction, the extension length of the first portion M38a is shorter than the extension length of the first portion M38b. In other respects, the first portions M38a and M38b are configured similarly to the first portions M8a and M8b.

[0078] As shown in FIG. 11( b), when processing an object 11 having a virtual surface M according to the fourth modification, in the first laser processing step, laser light L is irradiated under first processing conditions along first portions M38a, 38b of the virtual surface M to form a modified region 12a in a first slicing state. As shown in FIG. 11( c), in the second laser processing step following the first laser processing step, laser light L is irradiated under second processing conditions along the first surface M3 and the second surface M5 to form a modified region 12b in a second slicing state. As a result, the modified region 12a in the first slicing state, which has already been formed in the first laser processing step, undergoes crack propagation as the modified region 12b is formed, transforming into a modified region 12c in a second slicing state. This processing method also achieves the above-described effects.

[0079] 12(a), 12(b), and 12(c) are cross-sectional views of the object 11 illustrating laser processing along a virtual plane M according to a fifth modified example. As shown in FIG. 12(a), the virtual plane M according to the fifth modified example differs from the virtual plane M according to the above embodiment (see FIG. 5(a)) in that it includes a first portion M48 instead of the first portions M8a and M8b. The first portion M48 is an annular surface as viewed from the Z direction. The first portion M48 is an inclined curved surface that approaches the front surface 11a relative to the horizontal plane as it extends radially inward and is convex toward the back surface 11b in a cross-sectional view along the Z direction. The radially inner side of the first portion M48 is connected to the end of the first surface M3 on the back surface 11b side. The radially outer side of the first portion M48 is connected to the radially inner end of the second surface M5.

[0080] As shown in Figure 12(b), when processing an object 11 having a virtual surface M according to the fifth modification, in the first laser processing step, laser light L is irradiated along a first portion M48 of the virtual surface M under first processing conditions to form a modified region 12a in a first slicing state. As shown in Figure 12(c), in the second laser processing step following the first laser processing step, laser light L is irradiated along the first surface M3 and the second surface M5 under second processing conditions to form a modified region 12b in a second slicing state. As a result, the modified region 12a in the first slicing state, which has already been formed in the first laser processing step, undergoes crack propagation as the modified region 12b is formed, transforming into a modified region 12c in a second slicing state. This processing method also achieves the above-described effects.

[0081] 13(a), 13(b), and 13(c) are cross-sectional views of the target object 11 illustrating laser processing along the imaginary plane M according to the sixth modified example. As shown in Fig. 13(a), the imaginary plane M according to the sixth modified example differs from the imaginary plane M according to the above embodiment (see Fig. 5(a)) in that it includes a first surface M53, a second surface M55, and a first portion M58 instead of the first surface M3, the second surface M5, and the first portions M8a and M8b.

[0082] The first surface M53 is formed inside the object 11 along the boundary between the peripheral edge portion E and the main body portion R. The first surface M53 has a shape corresponding to the peripheral surface of a truncated cone, and is an inclined surface that slopes radially inward with respect to the Z direction as it approaches the front surface 11a. The second surface M55 is formed inside the peripheral edge portion E near the back surface 11b. The second surface M55 is an annular surface when viewed from the Z direction. The second surface M55 is an inclined surface that slopes radially inward with respect to the horizontal plane so as to approach the front surface 11a. The back surface 11b side of the first surface M53 connects to the radially inner end of the second surface M55. The connecting portion between the first surface M53 and the second surface M55 constitutes a first portion M58.

[0083] As shown in FIG. 13( b), when processing an object 11 having a virtual surface M according to the sixth modification, in the first laser processing step, laser light L is irradiated along the entire virtual surface M (first surface M53 and second surface M55) under first processing conditions to form modified region 12a in the first slicing state. As shown in FIG. 13( c), in the second laser processing step following the first laser processing step, laser light L is irradiated along the edge of second surface M55 on the first portion M58 side under second processing conditions to form modified region 12b in the second slicing state so as to overlap modified region 12a. As a result, a crack propagates in modified region 12a in the first slicing state, which has already been formed in the first laser processing step, as modified region 12b is formed, and the modified region 12c in the second slicing state is transformed into modified region 12c. This processing method also achieves the above-described effects.

[0084] 14(a), 14(b), and 14(c) are cross-sectional views of the object 11 illustrating laser processing along a virtual plane M according to the seventh modification. As shown in Fig. 14(a), the virtual plane M according to the seventh modification is similar to the virtual plane M according to the sixth embodiment (see Fig. 13(a)).

[0085] As shown in FIG. 14( b), when processing an object 11 having a virtual surface M according to the seventh modification, in the first laser processing step, laser light L is irradiated along the entire virtual surface M (first surface M53 and second surface M55) under first processing conditions to form modified region 12a in the first slicing state. As shown in FIG. 14( c), in the second laser processing step following the first laser processing step, laser light L is irradiated along the edge of first surface M53 on the first portion M58 side under second processing conditions to form modified region 12b in the second slicing state so as to overlap modified region 12a. As a result, the crack in modified region 12a in the first slicing state, which has already been formed in the first laser processing step, propagates with the formation of modified region 12b, and the modified region 12c in the second slicing state is transformed. This processing method also achieves the above-described effects.

[0086] 15(a), 15(b), and 15(c) are cross-sectional views of the object 11 illustrating laser processing along a virtual plane M according to the eighth modification. As shown in Fig. 15(a), the virtual plane M according to the eighth modification is similar to the virtual plane M according to the sixth embodiment (see Fig. 13(a)).

[0087] As shown in FIG. 15( b), when processing an object 11 having a virtual surface M according to the eighth modification, in the first laser processing step, laser light L is irradiated along the entire virtual surface M (first surface M53 and second surface M55) under the first processing conditions to form a modified region 12a in the first slicing state. As shown in FIG. 15( c), in the second laser processing step following the first laser processing step, laser light L is irradiated along an arbitrary portion of the first surface M53 (in the illustrated example, a portion from the center toward the surface 11a) under the second processing conditions to form a modified region 12b in the second slicing state so as to overlap the modified region 12a. As a result, the modified region 12a in the first slicing state, which has already been formed in the first laser processing step, undergoes crack propagation as the modified region 12b is formed, transforming into a modified region 12c in the second slicing state. This processing method also achieves the above-described effects.

[0088] In the above embodiment, the first slicing state is not particularly limited, and it is sufficient that at least some of the multiple cracks contained in the modified region 12 are not connected to each other in a direction intersecting the machining direction.

[0089] 16, the first slicing state may be a state in which, in a cross section along the Z direction of the target object 11, multiple cracks C1 extending from multiple modified spots 12s in a modified spot group G12 are connected to each other, and a crack C2 extending from a modified spot 12s included in one of adjacent modified spot groups G12 is not connected to a crack C3 extending from a modified spot 12s included in the other modified spot group G12. The modified spot group G12 is composed of two or more adjacent modified spots 12s, and the modified region 12 has a plurality of modified spot groups G12.

[0090] In such laser processing, for example, by increasing the output of one pulse of laser light L, it is possible to connect the cracks C1 from adjacent modified spots 12s in the modified spot group G12. Furthermore, for example, in a pair of adjacent modified spot groups G12, it is possible to prevent the cracks C2 and C3 from connecting to each other by widening the distance between one modified spot 12s and the other modified spot 12s. This makes it easier to connect multiple cracks and to extend the multiple cracks across the entire virtual surface M in the second laser processing step after the first laser processing step.

[0091] In the above embodiment, the object 11 is, for example, a silicon wafer (see FIG. 3(b) and the like), but the object is not particularly limited, and an object 111 that is a bonded wafer may be used as shown in FIG. 17 . The object 111 has a first substrate 151 and a second substrate 152. The first substrate 151 and the second substrate 152 correspond to the object 11.

[0092] A first device layer 161 including a plurality of functional elements is formed on the back surface 151b, which is the main surface of the first substrate 151. A second device layer 162 including a plurality of functional elements is formed on the front surface 152a, which is the main surface of the second substrate 152. The first substrate 151 and the second substrate 152 are bonded via the first device layer 161 and the second device layer 162. In such a bonded wafer object 111, the above-mentioned effects are particularly effective.

[0093] For example, in the case of the object 111, when the peripheral portion E is peeled off using the modified region 12 spanning the virtual surface M formed on the first substrate 151 as the boundary, the crack may extend radially inward from the bonding surface between the first device layer 161 and the second device layer 162, then cross the pattern of the first device layer 161 to reach the modified region 12 inside the first substrate 151, and extend along the modified region 12.

[0094] The second surface of the virtual surface M formed in the vicinity of the back surface 151b of the first substrate 151 of the object 111 is preferably closer to the back surface 151b, and may be set so that at least a portion of the second surface overlaps the back surface 151b. This makes it possible to reduce the amount of material to be removed by the unevenness flattening process when the unevenness flattening process is subsequently performed by laser processing or etching, thereby enabling faster processing times.

[0095] In the above embodiment, as shown in FIG. 18 , after the second laser processing step, a radial cutting step (periphery processing step) may be provided in which laser light L is irradiated along radial lines 5h, which are processing lines 5 extending radially from the inside to the outside of the peripheral edge E, to form a modified region 12. The radial lines 5h can be set using the GUI 9. The radial lines 5h are virtual lines. The radial lines 5h may be specified by coordinates. The radial lines 5h are planned radial cut lines along which the modified region is planned to be formed by the radial cutting step. The radial lines 5h extend linearly (radially) along the radial direction of the target object 11 as viewed from the laser light incident surface. In the illustrated example, multiple radial lines 5h are set so that the peripheral edge E is equally divided (here, divided into four) in the circumferential direction as viewed from the Z direction.

[0096] The radial cutting process is a process for separating the unnecessary portions to be removed by trimming. For example, in the radial cutting process, after the second laser processing process and before the peeling process, without rotating the stage 2, the laser processing head 3 controls the start and stop of irradiation of the laser light L under AF tracking control while the focusing position of the laser light L is positioned on the radial lines 5h on the target object 11, and the focusing position of the laser light L is moved along the radial lines 5h. This laser processing is repeatedly performed on all radial lines 5h, thereby forming one or more rows of modified regions 12 in the Z direction along the radial lines 5h. This radial cutting process makes it possible to reliably peel off the peripheral edge portion E.

[0097] In the above embodiment, when the virtual surface M includes a plurality of surfaces, the order of laser processing of these surfaces is not particularly limited, and the order may be random. In the above embodiment, the index direction is not particularly limited, and may be a direction from the radially inner side to the radially outer side, or a direction from the radially outer side to the radially inner side, or a combination of these directions depending on the situation.

[0098] In the above embodiment, there are no particular limitations on the type of object 11, the shape of object 11, the size of object 11, the number and directions of crystal orientations of object 11, and the plane orientation of the main surface of object 11. In the above embodiment, the vicinity of the back surface 11b includes, for example, a position close to the back surface 11b, a position close to the back surface 11b, a position around the back surface 11b, etc., and may also include a position on the back surface 11b and a position overlapping the back surface 11b.

[0099] In the above embodiment, the front surface 11a of the object 11 is the laser light incident surface, but the back surface 11b of the object 11 may also be the laser light incident surface. In the above embodiment, the modified region 12 may be, for example, a crystalline region, a recrystallized region, or a gettering region formed inside the object 11. The crystalline region is a region that maintains the structure of the object 11 before processing. The recrystallized region is a region that solidifies as a single crystal or polycrystal when resolidified after once evaporating, turning into plasma, or melting. The gettering region is a region that exhibits a gettering effect by collecting and capturing impurities such as heavy metals, and may be formed continuously or intermittently. The above embodiment may be applied to processing such as ablation.

[0100] In the above embodiment, the output of the laser light in the first laser processing step does not have to be constant. In the above embodiment, the intervals between the multiple cracks formed in the first laser processing step do not have to be constant. In the above embodiment, in the first laser processing step, the laser light L may be branched in the processing direction and / or the index direction to simultaneously form multiple modified spots 12s.

[0101] In the above embodiment, the pulse width of the irradiated laser light L may be different between the first laser processing step and the second laser processing step. By shortening the pulse width of the laser light L in the first laser processing step, it is possible to perform laser processing that is less likely to cause cracks to connect. By lengthening the pulse width of the laser light L in the first laser processing step, it is possible to create high-quality cracks across the entire area of ​​the virtual surface M in the second laser processing step. Furthermore, by shortening the pulse width of the laser light L in the first laser processing step, it is possible to more easily achieve the first processing condition in which cracks connect intermittently.

[0102] In the above embodiment, laser processing is performed along the first portions M8a and M8b of the imaginary surface M in the first laser processing step, and then laser processing is performed along the first and second surfaces M3 and M5 of the imaginary surface M in the second laser processing step. However, this is not limited to this. For example, after laser processing is performed along the first portions M8a and M8b of the imaginary surface M in the first laser processing step, if the following condition 1 and / or condition 2 are satisfied, laser processing may be performed only along the second surface M5 of the imaginary surface M in the second laser processing step (i.e., laser processing is not performed along the first surface M3), and the processing state of the modified region 12 along the first portions M8a and M8b and the second surface M5 may be a slicing full cut state. This enables shortening the tact time by not laser processing the first surface M3. In particular, when cracks from the first portions M8a and M8b reach the surface 11a, the desired processing results can be obtained while shortening the tact time.

[0103] Condition 1: When the processing state of the modified region 12 along the first portions M8a, M8b and the second surface M5 becomes a slicing full cut state, a crack also propagates along the first surface M3.

[0104] Condition 2: In the subsequent peeling step, peeling is performed on a surface corresponding to the first surface M3.

[0105] In the above embodiment and modified example, a portion of the peripheral edge portion E is peeled off at the boundary of the modified region 12 across the imaginary plane M. However, a portion of the main body portion R may also be peeled off (i.e., peeled off by hollowing out a portion of the main body portion R while leaving the peripheral edge portion E). In this case, for example, processing may be performed as exemplified below.

[0106] 19(a) to 19(c) and 20(a) to 20(c) are diagrams for explaining an object processing method and a semiconductor device manufacturing method according to an eleventh modification. As shown in Fig. 19(a), the imaginary surface M according to the eleventh modification has an imaginary body surface M10 formed along the back surface 11b inside the main body portion R, and an imaginary peripheral surface M20 formed from the outer edge of the imaginary body surface M10 to the back surface 11b and including a portion along the boundary between the peripheral edge portion E and the main body portion R. In the object 11, a processing line 5 having a plurality of parallel lines 5a arranged side by side is set on the imaginary surface M (see Fig. 4).

[0107] The imaginary body surface M10 is a circular surface parallel to the back surface 11b. The imaginary peripheral surface M20 includes an imaginary vertical surface (imaginary intersection surface) M21 extending perpendicular to (intersecting with) the back surface 11b along the boundary between the peripheral edge portion E and the main body portion R, and an imaginary connecting surface M22 connecting the imaginary body surface M10 and the imaginary vertical surface M21. The imaginary vertical surface M21 is a cylindrical surface formed at the boundary between the peripheral edge portion E and the main body portion R. Note that although the imaginary vertical surface M21 is included here as an imaginary intersection surface, it is sufficient that the imaginary intersection surface extends along the boundary between the peripheral edge portion E and the main body portion R so as to intersect with the back surface 11b. The imaginary connecting surface M22 is an imaginary surface extending in an outwardly convex curved shape from the outer edge of the imaginary body surface M10 to the end of the imaginary vertical surface M21. The imaginary connecting surface M22 is a bent portion of the imaginary surface M. The imaginary connecting surface M22 is an annular surface when viewed from a direction perpendicular to the surface 11a.

[0108] The first portion of the imaginary surface M that is the target of the dot line processing (first laser processing step) includes at least a part of the imaginary circumferential surface M20. In the illustrated example, the first portion includes the imaginary connecting surface M22.

[0109] As shown in Figure 19 (b), in the laser processing process of the 11th modified example, laser light L is irradiated under first processing conditions along the virtual connecting surface M22 on the virtual peripheral surface M20 of the virtual surface M to form a modified area 12a in a first slicing state (dot line processing: first laser processing process).

[0110] 19(c), after forming the modified region 12a along the imaginary joining surface M22, the laser beam L is irradiated under the second processing conditions along the imaginary vertical surface M21 on the imaginary peripheral surface M20 of the imaginary surface M to form the modified region 12b in the second slicing state (second laser processing step). As shown in FIG. 20(a), after forming the modified region 12b along the imaginary vertical surface M21, the laser beam L is irradiated under the second processing conditions along the imaginary main body surface M10 of the imaginary surface M to form the modified region 12b in the second slicing state (second laser processing step).

[0111] 20(b), in the second laser processing step, modified region 12b in the second slicing state is formed along imaginary vertical plane M21 and imaginary main body surface M10, and the cracks in modified region 12a in the first slicing state already formed in the first laser processing step extend with the formation of modified region 12b, changing into modified region 12c in the second slicing state. As a result, after the second laser processing step, the multiple cracks contained in modified region 12 connect to each other and extend across the entire area of ​​imaginary surface M (crack induction step).

[0112] 20(c), an external stress is applied to the object 11, and a portion of the main body R of the object 11 is peeled off, with the modified region 12 across the imaginary plane M as the boundary (peeling process). After the peeling process, the peeled object 11 (portion of the main body R) is cut into multiple chips (cutting process). Any method, such as laser dicing, blade dicing, or plasma dicing, can be used to cut the object 11 in the cutting process. This completes the method for manufacturing a semiconductor device.

[0113] The object processing method according to the eleventh modification also achieves the above-described effect of being able to prevent cracks from being unintentionally formed in the object 11 that do not follow the imaginary plane M. Furthermore, for example, in order to reuse the wafer, it is possible to peel off a part of the main body R of the object 11 while leaving the peripheral edge E.

[0114] Furthermore, while cracks that do not follow the virtual plane M tend to form in the area where the imaginary vertical plane M21 and the imaginary body surface M10 are connected, in this modified example, multiple cracks that are intermittently connected along the virtual connecting surface M22 are formed, which effectively guides the crack propagation and prevents cracks from forming from the virtual connecting surface M22 that do not follow the virtual plane M. Specifically, by performing dot line processing along the virtual connecting surface M22 that extends in a curved shape from the end of the imaginary vertical plane M21 to the outer edge of the imaginary body surface M10, the following effects are achieved: Bevel cracks, in which cracks along the imaginary vertical plane M21 in the object 11 extend to the surface 11a, can be prevented; Bevel cracks, in which cracks along the imaginary body surface M10 extend into the peripheral portion E, can be prevented; Compared to when the imaginary vertical plane M21 and the imaginary body surface M10 are connected at a right angle, deterioration in the quality of the area where the imaginary vertical plane M21 and the imaginary body surface M10 are connected can be prevented.

[0115] 21 , when laser processing is performed on the first substrate 151 of the object 111, which is a bonded wafer, in order to prevent bottom cracks, in which the cracks extend to the second substrate 152, which is not laser processed, it is preferable that the cracks do not reach the bonding region 19, which includes the device layer between the first substrate 151 and the second substrate 152. In this regard, in this modified example, in order to maintain a state in which the multiple cracks in the modified region 12a formed by dot line processing are intermittently connected (in other words, to prevent the multiple cracks in the modified region 12a formed by dot line processing from connecting), when forming the modified region 12b along the virtual vertical plane M21 (see FIG. 19( a)), the length of the crack C5 in the modified region 12b may be reduced (the laser processing related to the formation of the modified region 12b may be weakened). When the length of the crack C5 is small, the modified region 12b must be formed close to the back surface 11b in order for the crack C5 to reach the back surface 11b of the first substrate 151. In this case, the distance between the modified region 12b and the back surface 11b is short, so the radial swing range of the crack C5 can be reduced. When the swing range of the crack C5 is small, it becomes easier to control the bottom end of the crack C5, and it becomes possible to adjust the crack C5 so that it extends outside the bonding region 19 (so that the crack C5 does not extend into the bonding region 19). As a result, it becomes possible to suppress the bottom cracking described above.

[0116] 22(a) to 22(d) are diagrams for explaining a method for processing an object and a method for manufacturing a semiconductor device according to a twelfth modification. The twelfth modification differs from the eleventh modification in that the order of laser processing is different. Below, a description of the similarities to the eleventh modification will be omitted, and only the differences will be described.

[0117] 22(a), in the laser processing step according to the twelfth modification, before the first laser processing step, laser light L is irradiated along a virtual vertical plane M21 (see FIG. 19(a)) of the virtual plane M to form a modified region 12b (cross-crack processing step). Specifically, before the dot line processing, laser light L is irradiated along the virtual vertical plane M21 under the second processing conditions to form a modified region 12b in a second slicing state.

[0118] Next, as shown in Fig. 22(b), laser light L is irradiated along the imaginary connecting surface M22 of the imaginary surface M under the first processing conditions to form a modified region 12a in the first slicing state (dot line processing: first laser processing step).As shown in Fig. 22(c), laser light L is irradiated along the imaginary main body surface M10 of the imaginary surface M under the second processing conditions to form a modified region 12b in the second slicing state (second laser processing step).

[0119] 22(d), in the second laser processing step, modified region 12b in the second slicing state is formed along imaginary body surface M10, and the cracks in modified region 12a in the first slicing state already formed in the first laser processing step extend with the formation of modified region 12b, changing into modified region 12c in the second slicing state. As a result, after the second laser processing step, the multiple cracks in modified region 12 connect to each other and extend across the entire imaginary surface M.

[0120] The object processing method according to the twelfth modification also achieves the above-described effect of being able to suppress the unintentional formation of cracks that do not follow the virtual surface M in the object 11. In addition, the effect of being able to suppress the formation of cracks that do not follow the virtual surface M from the virtual connecting surface M22 can be specifically realized.

[0121] 23(a) to 23(d) are diagrams illustrating a method for processing an object and a method for manufacturing a semiconductor device according to a thirteenth modification. As shown in FIG. 23(a), the thirteenth modification differs from the twelfth modification in that the imaginary plane M has an imaginary connecting plane M24 having a frustum-shaped peripheral surface instead of the imaginary connecting plane M22 (see FIG. 22(a)). The imaginary connecting plane M24 is an imaginary plane that extends from the outer edge of the imaginary main body plane M10 to the end of the imaginary vertical plane M21, outward and toward the back surface 11b. Below, a description of the similarities to the twelfth modification will be omitted, and only the differences will be described.

[0122] As shown in Figure 23(a), in the laser processing step according to the thirteenth modification, before the first laser processing step, laser light L is irradiated along a virtual vertical plane M21 (see Figure 19(a)) of the virtual plane M to form a modified region 12b (cross-crack processing step). As shown in Figure 23(b), laser light L is irradiated along a virtual connecting plane M24 of the virtual plane M under first processing conditions to form a modified region 12a in the first slicing state (dot line processing: first laser processing step). As shown in Figure 23(c), laser light L is irradiated along a virtual main body surface M10 of the virtual plane M under second processing conditions to form a modified region 12b in the second slicing state (second laser processing step).

[0123] 23(d), in the second laser processing step, modified region 12b in the second slicing state is formed along imaginary body surface M10, and the cracks in modified region 12a in the first slicing state already formed in the first laser processing step extend along with the formation of modified region 12b, changing into modified region 12c in the second slicing state. As a result, after the second laser processing step, the multiple cracks in modified region 12 connect to each other and extend across the entire imaginary surface M.

[0124] The object processing method according to the thirteenth modified example also achieves the above-described effect of being able to suppress the unintentional formation of cracks that do not follow the virtual surface M in the object 11. In addition, the effect of being able to suppress the formation of cracks that do not follow the virtual surface M from the virtual connecting surface M24 can be specifically realized.

[0125] 24(a) to 24(d) are diagrams for explaining a method for processing an object and a method for manufacturing a semiconductor device according to a fourteenth modification. The fourteenth modification differs from the eleventh modification in that the order of laser processing is different. Below, a description of the similarities to the eleventh modification will be omitted, and only the differences will be described.

[0126] 24(a), in the laser processing step according to the fourteenth modification, before the first laser processing step, a laser beam L is irradiated along the imaginary body surface M10 (see FIG. 19(a)) of the imaginary surface M to form a modified region 12b (body crack processing step). Specifically, before the dot line processing, a laser beam L is irradiated along the imaginary body surface M10 under the second processing conditions to form a modified region 12b in a second slicing state.

[0127] Next, as shown in Fig. 24(b), laser light L is irradiated along a virtual connecting plane M22 of the virtual plane M under the first processing conditions to form a modified region 12a in a first slicing state (dot line processing: first laser processing step).As shown in Fig. 24(c), laser light L is irradiated along a virtual vertical plane M21 of the virtual plane M under the second processing conditions to form a modified region 12b in a second slicing state (second laser processing step).

[0128] 24(d), in the second laser processing step, modified region 12b in the second slicing state is formed along imaginary vertical plane M21, and the cracks in modified region 12a in the first slicing state already formed in the first laser processing step extend along with the formation of modified region 12b, changing into modified region 12c in the second slicing state. As a result, after the second laser processing step, the multiple cracks contained in modified region 12 are connected to each other and extend across the entire area of ​​imaginary plane M.

[0129] The object processing method according to the fourteenth modification also achieves the above-described effect of being able to suppress the unintentional formation of cracks that do not follow the virtual surface M in the object 11. In addition, the effect of being able to suppress the formation of cracks that do not follow the virtual surface M from the virtual connecting surface M22 can be specifically realized.

[0130] 25(a) to 25(d) are diagrams for explaining a method for processing an object and a method for manufacturing a semiconductor device according to a fifteenth modified example. The fifteenth modified example differs from the eleventh modified example in that the imaginary circumferential surface M20 is formed by an imaginary curved surface M25. Below, a description of the similarities to the eleventh modified example will be omitted, and only the differences will be described.

[0131] The imaginary curved surface M25 is an imaginary surface that extends in an outwardly convex curved shape from the outer edge of the imaginary main body surface M10 toward the back surface 11b and reaches the back surface 11b. The imaginary curved surface M25 is a bent portion of the imaginary surface M. The imaginary curved surface M25 is an annular surface when viewed from a direction perpendicular to the front surface 11a. The first portion of the imaginary surface M that is the target of dot line processing (first laser processing step) includes the imaginary circumferential surface M20 (imaginary curved surface M25).

[0132] 25(b), in the laser processing step according to the fifteenth modification, laser light L is irradiated under first processing conditions along a virtual curved surface M25 of the virtual surface M to form a modified region 12a in a first slicing state (dot line processing: first laser processing step). As shown in FIG. 25(c), laser light L is irradiated under second processing conditions along a virtual main body surface M10 of the virtual surface M to form a modified region 12b in a second slicing state (second laser processing step).

[0133] 25(d), in the second laser processing step, modified region 12b in the second slicing state is formed along imaginary body surface M10, and the cracks in modified region 12a in the first slicing state already formed in the first laser processing step extend with the formation of modified region 12b, changing into modified region 12c in the second slicing state. As a result, after the second laser processing step, the multiple cracks contained in modified region 12 connect to each other and extend across the entire area of ​​imaginary surface M.

[0134] The object processing method according to the fifteenth modification also achieves the above-described effect of preventing cracks from unintentionally forming in the object 11 that do not follow the imaginary surface M. In this modification, the portion of the imaginary surface M that is the target of dot line processing may have an imaginary conical surface having a frustum-shaped peripheral surface instead of the imaginary curved surface M25. The imaginary conical surface is an imaginary surface that extends from the outer edge of the imaginary body surface M10 outward and toward the back surface 11b, and reaches the back surface 11b.

[0135] The respective components in the above-described embodiments and modifications are not limited to the materials and shapes described above, and various materials and shapes can be applied. Furthermore, the respective components in the above-described embodiments or modifications can be arbitrarily applied to the respective components in other embodiments or modifications.

[0136] 5...processing line, 5a...parallel line, 5h...radial line, 11...object (first substrate, second substrate), 11a...surface (main surface), 11b...back surface (main surface), 12, 12a, 12b, 12c...modified region, 12s...modified spot, 111...object, 161...first device layer, 162...second device layer, C1, C2, C3...crack, E...periphery, G12 ...modification spot group, M3, M13, M23, M53...first surface, M5, M55...second surface, M8a, M8b, M18, M28a, M28b, M38a, M38b, M48, M58...first part, M10...imaginary main body surface, M20...imaginary peripheral surface, M21...imaginary vertical surface (imaginary intersection surface), M22, M24...imaginary connecting surface, L...laser light, M...imaginary surface, R...main body part.

Claims

1. An object processing method for processing an object, comprising a laser processing step of forming a modified region along a virtual surface inside the object by irradiating the object with a laser beam, wherein the laser processing step includes: a first laser processing step of irradiating the laser beam under a first processing condition along at least a first portion of the virtual surface to form the modified region; and a second laser processing step of irradiating the laser beam under a second processing condition along the virtual surface after the first laser processing step to form the modified region, wherein the first processing condition is a condition under which a plurality of cracks included in the modified region are intermittently connected, and the second processing condition is a condition under which a plurality of cracks included in the modified region formed by the first and second laser processing steps are connected to each other after the second laser processing step and extend over the entire area of the virtual surface.

2. In the first and second laser processing steps, the modified region is formed by irradiating the laser beam along a processing line having a plurality of parallel lines arranged side by side on the virtual surface, wherein the first processing condition is a condition under which the processing state of the modified region of the first portion after the first laser processing step is in a first slicing state, and the second processing condition is a condition under which the processing state of the modified region over the entire virtual surface after the second laser processing step is in a second slicing state, wherein the first slicing state is a state in which at least some of the plurality of cracks included in the modified region are not connected to each other in a direction intersecting the processing progress direction, and the second slicing state is a state in which the plurality of cracks included in the modified region extend and are connected to each other in the processing progress direction and a direction intersecting the processing progress direction. The object processing method according to claim 1.

3. The object processing method according to claim 2, wherein the first slicing state is a state in which at least some of the plurality of cracks included in the modified region are not connected to each other in the processing progress direction and a direction intersecting the processing progress direction.

4. The modified region includes a plurality of groups of modified spots each composed of two or more adjacent modified spots. The first slicing state is such that, in a cross-section intersecting the virtual plane of the object, a plurality of cracks extending from the plurality of modified spots in the group of modified spots are connected to each other, and cracks extending from the modified spots included in any one of the adjacent groups of modified spots are not connected to cracks extending from the modified spots included in any other group. The object processing method according to claim 2 or 3.

5. The object has a front surface and a back surface opposite to the front surface, and includes a peripheral portion located at the periphery and a main body portion inside the peripheral portion when viewed from the direction facing the front surface. The virtual plane has a first plane formed inside the object along the boundary between the peripheral portion and the main body portion, and a second plane formed near the back surface inside the peripheral portion. The first portion includes at least a portion connecting the first plane and the second plane. The object processing method according to claim 1 or 2.

6. In the second laser processing step, the modified region is formed by irradiating the laser light along a portion of the virtual plane other than the first portion. The object processing method according to claim 1 or 2.

7. After the laser processing step, a peeling step of peeling the peripheral portion with the modified region across the virtual plane as a boundary is provided. The object processing method according to claim 5.

8. Before the peeling step, a peripheral portion processing step of forming the modified region by irradiating the laser light along a radial line extending radially from the inside to the outside in the peripheral portion is provided. The object processing method according to claim 7.

9. Before the first laser processing step, a step of equalizing at least one of the reflectivity and transmittance on the laser light incident surface of the object is provided. The object processing method according to claim 1 or 2.

10. When the object has a film on the laser light incident surface side, in the step of equalizing at least one of the reflectivity and transmittance on the laser light incident surface, the film is removed by irradiating the film with laser light or performing etching. The object processing method according to claim 9.

11. The object has a first substrate and a second substrate. A first device layer is formed on the main surface of the first substrate, and a second device layer is formed on the main surface of the second substrate. The first substrate and the second substrate are joined via the first device layer and the second device layer. The object processing method according to claim 1 or 2.

12. The object has a front surface and a back surface opposite to the front surface. When viewed from the direction facing the front surface, it is configured to include a peripheral portion located at the periphery and a main body portion inside the peripheral portion. The virtual surface includes a virtual main body surface formed along the back surface inside the main body portion, and a virtual peripheral surface formed from the outer edge of the virtual main body surface to the back surface and including a portion along the boundary between the peripheral portion and the main body portion. The first portion includes at least a part of the virtual peripheral surface. The object processing method according to claim 1 or 2.

13. The virtual peripheral surface includes a virtual intersection surface extending along the boundary between the peripheral portion and the main body portion and intersecting the back surface, and a virtual connection surface connecting the virtual main body surface and the virtual intersection surface. The first portion includes the virtual connection surface. The laser processing step further includes an intersection crack processing step of irradiating the laser light along the virtual intersection surface to form the modified region before the first laser processing step. The second processing condition is a condition such that a plurality of cracks included in the modified region formed by the intersection crack processing step and the first and second laser processing steps are connected to each other after the second laser processing step and extend over the entire area of the virtual surface. The object processing method according to claim 12.

14. The virtual peripheral surface includes a virtual intersection surface extending so as to intersect the back surface along the boundary between the peripheral portion and the main body portion, and a virtual connection surface connecting the virtual main body surface and the virtual intersection surface. The first portion includes the virtual connection surface. The laser processing step further includes a main body crack processing step of irradiating the laser beam along the virtual main body surface to form the modified region before the first laser processing step. The second processing condition is a condition in which a plurality of cracks included in the modified region formed by the main body crack processing step and the first and second laser processing steps are connected to each other after the second laser processing step and extend over the entire area of the virtual surface. The object processing method according to claim 12.

15. A method for manufacturing a semiconductor device, comprising: the laser processing step included in the object processing method according to claim 1; a peeling step of peeling the object along the virtual surface after the laser processing step; and a cutting step of cutting the object into a plurality of chips after the peeling step.

Images