Laser processing method, method for manufacturing semiconductor device, and laser processing device

Abstract

This laser processing method is provided with: a first processing step which performs laser processing along a first planned formation surface; and a second processing step which performs laser processing along a second planned formation surface. In the first and second processing steps, the laser light is shaped so that the focused region of the laser light has a longitudinal direction when viewed from the Z direction, and the longitudinal direction intersects a processing progress direction. In the first processing step, laser processing is performed under a first processing condition for extending a crack from a modified region along the first planned formation surface, and in the second processing step, laser processing is performed under a second processing condition for extending a crack from the modified region along the second planned formation surface. An inclination angle of the second planned formation surface is larger than an inclination angle of the first planned formation surface.

Description

Laser processing method, method for manufacturing a semiconductor device, and laser processing apparatus

[0001] The present disclosure relates to a laser processing method, a method for manufacturing a semiconductor device, and a laser processing apparatus.

[0002] A laser processing method is known in which laser light is irradiated along a virtual plane set on an object to form a modified region on the object (see, for example, Patent Document 1). The modified region formed by the laser processing method and the cracks extending from the modified region can be used for cutting the object. In such a laser processing method, the condensing region of the laser light may have a longitudinal direction when viewed from the Z direction intersecting the laser light incident surface, and the laser light may be shaped so that the longitudinal direction intersects the processing progress direction. Thereby, even when there is a deviation between, for example, the splitting direction of the object and the cutting direction of the object (the extending direction of the cutting surface), the occurrence of twist hackle on the cutting surface is suppressed.

[0003] International Publication No. 2022 / 014106

[0004] In the above laser processing method, cracks extending obliquely with respect to the Z direction are formed from the modified region toward the opposite surface of the object on the side opposite to the laser light incident surface. Thereby, it is possible to suppress the cracks from extending to another object (for example, another wafer bonded to the wafer as the object, hereinafter also simply referred to as "another object") disposed adjacent to the opposite surface side of the object. However, in this case, the effect of suppressing the occurrence of the above-described twist hackle may be weakened, and the quality of the cutting surface may deteriorate.

[0005] Therefore, an object of the present disclosure is to provide a laser processing method, a method for manufacturing a semiconductor device, and a laser processing apparatus that can suppress the cracks from extending to another object and can suppress the deterioration of the quality of the cutting surface.

[0006] The laser processing method according to the present disclosure is a laser processing method for forming a modified region on an object by irradiating the object with laser light along a virtual surface set on the object, wherein the virtual surface includes a first planned formation surface set to be annular when viewed from the Z direction intersecting the laser light incident surface of the object, and a second planned formation surface set to be annular with the Z direction as its axial direction and continuous with the laser light incident surface side of the first planned formation surface, and comprises a first processing step of performing laser processing along the first planned formation surface and a second processing step of performing laser processing along the second planned formation surface, wherein the first and second processing steps In this laser processing method, the laser beam is shaped such that, when viewed from the Z direction, the focused area of ​​the laser beam has a longitudinal direction, and the longitudinal direction intersects with the processing progress direction, which is the direction of movement of the focused area; in the first processing step, laser processing is performed under first processing conditions to extend a crack from the modified area along the first planned surface to be formed; and in the second processing step, laser processing is performed under second processing conditions to extend a crack from the modified area along the second planned surface to be formed, and the inclination angle of the second planned surface to be formed with respect to the Z direction is greater than the inclination angle of the first planned surface to be formed with respect to the Z direction.

[0007] The laser processing apparatus according to the present disclosure

[10] "A laser processing apparatus that forms a modified region on an object by performing laser processing by irradiating a laser beam along a virtual surface set on the object, comprising: a support unit for supporting the object; an irradiation unit for irradiating the laser beam toward the object supported by the support unit; a moving unit for moving the focusing region of the laser beam relative to the object; and a control unit for controlling the moving unit and the irradiation unit, wherein the virtual surface includes a first planned formation surface set to be an annular shape with the Z direction as its axial direction intersecting the laser beam incident surface of the object, and a second planned formation surface set to be an annular shape with the Z direction as its axial direction and continuous with the laser beam incident surface side of the first planned formation surface, and the irradiation unit is viewed from the Z direction The laser processing apparatus has a forming section that shapes the laser beam such that the focusing region of the laser beam has a longitudinal direction and the longitudinal direction intersects with the processing progress direction which is the direction of movement of the focusing region, and the control unit performs a first processing process that performs laser processing along the first planned surface to be formed, and a second processing process that performs laser processing along the second planned surface to be formed, wherein in the first processing process, laser processing is performed under first processing conditions for extending a crack from the modified region along the first planned surface to be formed, and in the second processing process, laser processing is performed under second processing conditions for extending a crack from the modified region along the second planned surface to be formed, and the inclination angle of the second planned surface to be formed with respect to the Z direction is larger than the inclination angle of the first planned surface to be formed with respect to the Z direction.

[0008] In the laser processing method and laser processing apparatus according to this disclosure, the laser beam is shaped such that, when viewed from the Z direction, the focused region of the laser beam has a longitudinal direction, and this longitudinal direction intersects the processing direction. This makes it possible to suppress the occurrence of twisted hackle on the cut surface, even if there is a discrepancy between the cleavage direction and the cutting direction of the object. Furthermore, since at least the second planned formation surface is inclined with respect to the Z direction, cracks (hereinafter also referred to as "oblique cracks") that extend inclined with respect to the Z direction toward the opposite surface opposite to the laser beam incidence surface can be formed from the modified region, and as a result, the propagation of cracks to another object can be suppressed. Here, when cracks are formed along the first and second planned formation surfaces, it is found that by making the inclination angle of the second planned formation surface with respect to the Z direction larger than the inclination angle of the first planned formation surface with respect to the Z direction, the weakening of the effect of suppressing the occurrence of twisted hackle can be suppressed, and the effect can be fully exerted. Therefore, according to this disclosure, it is possible to suppress the propagation of cracks to another object and to suppress the deterioration of the quality of the cut surface.

[0009] The laser processing method according to this disclosure may also be [2] "the laser processing method according to [1], wherein the second processing condition is a condition in which the intensity of coma aberration imparted to the laser light is stronger than that of the first processing condition." In this case, laser processing that forms a crack along a second planned surface inclined with respect to the Z direction can be specifically realized.

[0010] The laser processing method according to this disclosure may also be [3] "the laser processing method according to [2], wherein in the first and second processing steps, the laser light is modulated according to a modulation pattern, the first processing condition uses a first modulation pattern as the modulation pattern, and the second processing condition uses a second modulation pattern as the modulation pattern that imparts a second coma aberration to the laser light that is stronger than the intensity of the first coma aberration that the first modulation pattern imparts to the laser light." In this case, the first and second coma aberrations can be imparted to the laser light by utilizing the modulation pattern.

[0011] The laser processing method according to this disclosure may also be [4] "the laser processing method according to any one of [1] to [3], wherein the first planned surface to be formed is a surface along the Z direction." In this case, it becomes possible to form a crack along the Z direction in the first processing step. In this case, it becomes possible to further suppress the occurrence of twisted hackles.

[0012] The laser processing method according to this disclosure may also be [5] "the laser processing method according to any one of [1] to [4], further comprising a third processing step of performing laser processing along the third processing step, wherein the virtual surface further includes a third surface to be formed which is a surface along the Z direction and continuous with the laser light incident surface side of the second surface to be formed." In this case, the third processing step can form a modified region along the Z direction so as to be continuous with the crack along the second surface to be formed. In this case, for example, removal of a part of the object (object to be removed) after laser processing becomes easier.

[0013] The laser processing method according to the present disclosure includes: [6] "The object has a crystal structure including a (100) plane, one (110) plane, another (110) plane, a first crystal orientation perpendicular to the one (110) plane, and a second crystal orientation perpendicular to the other (110) plane, wherein the (100) plane is the laser light incident plane, and the object has an annular line set on it, which includes an arc-shaped first region and an arc-shaped second region having a boundary with the first region when viewed from the Z direction, and by moving the focusing region relative to the first region of the line, the modified region is applied to the object along the first region The laser processing method is as described in any of [1] to [5], comprising: a first region processing step for forming a region; and a second region processing step for forming the modified region on the object along the second region by relatively moving the focusing region along the second region of the line, wherein in the first and second region processing steps, the laser beam is shaped such that the longitudinal direction of the focusing region is inclined with respect to the processing direction in a direction that approaches the one of the first and second crystal orientations that has a larger angle with respect to the processing direction.

[0014] In this case, when a crack extending from the modified region is pulled, for example, towards the first crystal orientation, the longitudinal direction of the laser beam's focusing region (beam shape) is not aligned with the processing direction, but rather tilted to approach the second crystal orientation, which is opposite to the first crystal orientation relative to the processing direction. This causes the crack propagation force due to the elongated beam shape to counteract the crack propagation force due to the crystal orientation (crystal axis), allowing the crack to grow precisely along the processing direction. Similarly, when a crack extending from the modified region is pulled, for example, towards the second crystal orientation, the longitudinal direction of the beam shape is not aligned with the processing direction, but rather tilted to approach the first crystal orientation, which is opposite to the second crystal orientation relative to the processing direction. This causes the crack propagation force due to the elongated beam shape to counteract the crack propagation force due to the crystal orientation, allowing the crack to grow precisely along the processing direction. Therefore, it is possible to suppress the deterioration of the cut surface quality.

[0015] The laser processing method according to this disclosure may also be [7] "the laser processing method according to any one of [1] to [6], which includes a removal step of removing at least a region in the object from the laser light incident surface to a depth including the second planned formation surface." In this case, the removal step can remove a portion of the object that includes a crack along the second planned formation surface.

[0016] The laser processing method according to this disclosure may also be [8] "the laser processing method according to any one of [1] to [7], wherein in the first processing step, a row of the modified regions is formed on the object along the first planned surface." In this case, efficient laser processing is possible in the first processing step. In this case, it is also possible to improve tact while maintaining the effect of suppressing the generation of twisted hackles.

[0017] The method for manufacturing a semiconductor device according to this disclosure is [9] "a method for manufacturing a semiconductor device comprising: first and second processing steps included in the laser processing method described in any of [1] to [8]; a peeling step performed after the first and second processing steps to peel the object along the virtual surface; and a dividing step performed after the peeling step to divide the object into a plurality of chips." In this case as well, since the laser processing method is performed, the above-mentioned effects are achieved, which include suppressing the propagation of cracks to other objects and suppressing the deterioration of the quality of the cut surface.

[0018] This disclosure makes it possible to provide a laser processing method, a semiconductor device manufacturing method, and a laser processing apparatus that can suppress the propagation of cracks to another object and suppress the deterioration of the quality of the cut surface.

[0019] Figure 1 is a schematic diagram showing the configuration of a laser processing apparatus according to one embodiment. Figure 2 is a schematic diagram showing the configuration of the laser irradiation unit shown in Figure 1. Figure 3 is a diagram showing the 4f lens unit shown in Figure 2. Figure 4 is a diagram showing the spatial light modulator shown in Figure 2. Figure 5(a) is a cross-sectional view of the object to illustrate the findings of oblique crack formation. Figure 5(b) is another cross-sectional view of the object to illustrate the findings of oblique crack formation. Figure 6 is a cross-sectional view of the object to illustrate the findings of oblique crack formation. Figure 7 is a diagram showing the beam shape of the laser light focusing region. Figure 8 is a diagram showing the offset of the modulation pattern. Figure 9(a) is a cross-sectional photograph showing the state of oblique crack formation. Figure 9(b) is another cross-sectional photograph showing the state of oblique crack formation. Figure 10 is a plan view of the object. Figure 11(a) is a plan view of the object. Figure 11(b) is a side view of the object. Figure 12(a) is a schematic diagram showing an example of the beam shape of the focusing region. Figure 12(b) is another schematic diagram showing an example of the beam shape of the focusing region. Figure 12(c) is yet another schematic diagram showing an example of the beam shape of the focusing region. Figure 13(a) is another schematic diagram showing another example of the beam shape of the focusing region. Figure 13(b) is yet another schematic diagram showing another example of the beam shape of the focusing region. Figure 13(c) is yet another schematic diagram showing another example of the beam shape of the focusing region. Figure 14(a) is a schematic side view illustrating the trimming process. Figure 14(b) is a schematic plan view continuing from Figure 14(a). Figure 14(c) is a schematic side view showing the object in Figure 14(b). Figure 15(a) is a schematic side view continuing from Figure 14(b). Figure 15(b) is a schematic plan view continuing from Figure 15(a). Figure 16(a) is a schematic plan view continuing from Figure 15(b). Figure 16(b) is a schematic side view showing the object in Figure 16(a). Figure 16(c) is a schematic plan view continuing from Figure 16(a). Figure 17 is a diagram showing one step of the trimming process. Figure 18(a) is a plan view showing one step of the trimming process. Figure 18(b) is a schematic diagram illustrating the beam shape in one step of the trimming process. Figure 19(a) is a plan view showing one step of the trimming process. Figure 19(b) is a schematic diagram illustrating the beam shape in one step of the trimming process.Figure 20(a) is a plan view showing an object to be laser processed according to the first embodiment. Figure 20(b) is a side view showing an object to be laser processed according to the first embodiment. Figure 21(a) is a partial cross-sectional view of an object to explain the laser processing method according to the first embodiment. Figure 21(b) is a partial cross-sectional view to explain the continuation of Figure 21(a). Figure 22(a) is a partial cross-sectional view to explain the continuation of Figure 21(b). Figure 22(b) is a partial cross-sectional view to explain the continuation of Figure 22(a). Figure 23 is a partial cross-sectional view to explain the continuation of Figure 22(b). Figure 24 is a diagram showing the relationship between coma intensity and the inclination angle of oblique cracks. Figure 25 is a diagram showing the relationship between the offset deviation of the modulation pattern, the inclination angle of the cracks, and the strength of coma aberration. Figure 26(a) is a partial cross-sectional view of an object to explain the laser processing method according to the second embodiment. Figure 26(b) is a partial cross-sectional view to explain the continuation of Figure 26(a).

[0020] The embodiments will be described in detail below with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations may be omitted. Each drawing may show a Cartesian coordinate system defined by the X, Y, and Z axes.

[0021] [Outline of Laser Processing Apparatus and Laser Processing] Figure 1 is a schematic diagram showing the configuration of a laser processing apparatus 1 according to one embodiment. As shown in Figure 1, the laser processing apparatus 1 comprises a stage (support unit) 2, an irradiation unit 3, moving units 4 and 5, and a control unit 6. The laser processing apparatus 1 is a device that forms a modified region 12 on an object 11 by performing laser processing, which involves irradiating the object 11 with laser light L along a virtual plane set on the object 11.

[0022] Stage 2 supports the object 11, for example, by holding a film attached to the object 11. Stage 2 is rotatable about an axis parallel to the Z direction. Stage 2 may also be movable along the X and Y directions. The X and Y directions are the first and second horizontal directions, which intersect (are orthogonal to each other), and the Z direction is the vertical direction.

[0023] The irradiation unit 3 focuses a laser beam L that is penetrating to the object 11 and irradiates the object 11 with it. When the laser beam L is focused inside the object 11 supported by the stage 2, the laser beam L is particularly absorbed in the portion corresponding to the focusing region C of the laser beam L (for example, the center Ca described later), and a modified region 12 is formed inside the object 11. The focusing region C is a predetermined range from the position where the beam intensity of the laser beam L is highest or the centroid of the beam intensity, although this will be explained in detail later.

[0024] 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 modified regions 12 include melted regions, cracked regions, dielectric breakdown regions, and refractive index change regions. The modified region 12 can be formed such that cracks extend from the modified region 12 toward the incident side of the laser beam L and the opposite side. Such modified regions 12 and cracks can be used, for example, to cut an object 11.

[0025] For example, when stage 2 is moved along the X direction and the focusing region C is moved relative to the object 11 along the X direction, multiple modified spots 12s are formed in a line along the X direction. Each modified spot 12s is formed by irradiation with one pulse of laser light L. A line of modified regions 12 is a collection of multiple modified spots 12s arranged in a line. Adjacent modified spots 12s may be connected to each other or separated from each other, depending on the relative movement speed of the focusing region C with respect to the object 11 and the repetition frequency of the laser light L.

[0026] The moving unit 4 includes a first moving unit 41 that moves the stage 2 in one direction within a plane intersecting (orthogonal to) the Z direction, and a second moving unit 42 that moves the stage 2 in another direction within the plane intersecting (orthogonal to) the Z direction. For example, the first moving unit 41 moves the stage 2 along the X direction, and the second moving unit 42 moves the stage 2 along the Y direction. The moving unit 4 also rotates the stage 2 around an axis parallel to the Z direction. The moving unit 5 supports the irradiation unit 3. The moving unit 5 moves the irradiation unit 3 along the X, Y, and Z directions. When the stage 2 and / or the irradiation unit 3 are moved while the focused area C of the laser light L is formed, the focused area C is moved relative to the object 11. That is, the moving units 4 and 5 move at least one of the stage 2 and the irradiation unit 3 in order to move the focused area C of the laser light L relative to the object 11.

[0027] The control unit 6 controls the operation of the stage 2, the irradiation unit 3, and the moving units 4 and 5. The control unit 6 has a processing unit, a storage unit, and an input receiving unit (not shown). The processing unit is configured as a computer device including a processor, memory, storage, and communication devices. In the processing unit, the processor executes software (programs) loaded into memory, etc., and controls the reading and writing of data in memory and storage, as well as communication by the communication devices. The storage unit is, for example, a hard disk, and stores various types of data. The input receiving unit is an interface unit that displays various types of information and accepts input of various types of information from the user. The input receiving unit constitutes a GUI (Graphical User Interface).

[0028] Figure 2 is a schematic diagram showing the configuration of the irradiation unit shown in Figure 1. Figure 2 shows a hypothetical line A indicating the planned laser processing. As shown in Figure 2, the irradiation unit 3 includes a light source 31, a spatial light modulator (shaping unit) 7, a focusing lens 33, and a 4f lens unit 34. The light source 31 outputs laser light L, for example, by a pulse oscillation method. The irradiation unit 3 may also be configured to not have a light source 31, and to introduce laser light L from outside the irradiation unit 3. The spatial light modulator 7 modulates the laser light L output from the light source 31. The focusing lens 33 focuses the laser light L, which has been modulated by the spatial light modulator 7 and output from the spatial light modulator 7, toward the object 11.

[0029] As shown in Figure 3, the 4f lens unit 34 has a pair of lenses 34A and 34B arranged on the optical path of the laser beam L from the spatial light modulator 7 to the focusing lens 33. The pair of lenses 34A and 34B constitute a double-sided telecentric optical system in which the modulation surface 7a of the spatial light modulator 7 and the entrance pupil surface (pupil surface) 33a of the focusing lens 33 are in an imaging relationship. As a result, the image of the laser beam L on the modulation surface 7a of the spatial light modulator 7 (the image of the laser beam L modulated in the spatial light modulator 7) is transferred (imaged) onto the entrance pupil surface 33a of the focusing lens 33. In the figure, Fs represents the Fourier plane.

[0030] As shown in Figure 4, the spatial light modulator 7 is a reflective liquid crystal on silicon (LCOS) spatial light modulator (SLM). The spatial light modulator 7 is constructed by stacking a drive circuit layer 72, a pixel electrode layer 73, a reflective film 74, an alignment film 75, a liquid crystal layer 76, an alignment film 77, a transparent conductive film 78, and a transparent substrate 79 on a semiconductor substrate 71 in this order.

[0031] The semiconductor substrate 71 is, for example, a silicon substrate. The drive circuit layer 72 constitutes an active matrix circuit on the semiconductor substrate 71. The pixel electrode layer 73 includes a plurality of pixel electrodes 73a arranged in a matrix along the surface of the semiconductor substrate 71. Each pixel electrode 73a is formed of a metallic material such as aluminum. A voltage is applied to each pixel electrode 73a by the drive circuit layer 72.

[0032] The reflective film 74 is, for example, a dielectric multilayer film. The alignment film 75 is provided on the surface of the liquid crystal layer 76 that is on the side of the reflective film 74, and the alignment film 77 is provided on the surface of the liquid crystal layer 76 that is on the side opposite to the reflective film 74. Each alignment film 75 and 77 is formed from a polymer material such as polyimide, and the contact surface of each alignment film 75 and 77 with the liquid crystal layer 76 is subjected to, for example, a rubbing treatment. The alignment films 75 and 77 align the liquid crystal molecules 76a contained in the liquid crystal layer 76 in a certain direction.

[0033] The transparent conductive film 78 is provided on the surface of the transparent substrate 79 on the alignment film 77 side, and faces the pixel electrode layer 73 with the liquid crystal layer 76 in between. The transparent substrate 79 is, for example, a glass substrate. The transparent conductive film 78 is formed of, for example, a light-transmitting and conductive material such as ITO. The transparent substrate 79 and the transparent conductive film 78 transmit laser light L.

[0034] In the spatial light modulator 7 configured as described above, when a signal indicating a modulation pattern is input from the control unit 6 to the drive circuit layer 72, a voltage corresponding to the signal is applied to each pixel electrode 73a, and an electric field is formed between each pixel electrode 73a and the transparent conductive film 78. When this electric field is formed, the arrangement direction of liquid crystal molecules 76a changes in the liquid crystal layer 76 for each region corresponding to each pixel electrode 73a, and the refractive index changes for each region corresponding to each pixel electrode 73a. This state is the state in which the modulation pattern is displayed on the liquid crystal layer 76. The modulation pattern is for modulating the laser light L.

[0035] In other words, when a modulation pattern is displayed on the liquid crystal layer 76, and a laser beam L is incident on the liquid crystal layer 76 from the outside via the transparent substrate 79 and the transparent conductive film 78, reflected by the reflective film 74, and emitted from the liquid crystal layer 76 to the outside via the transparent conductive film 78 and the transparent substrate 79, the laser beam L is modulated according to the modulation pattern displayed on the liquid crystal layer 76. Thus, with the spatial light modulator 7, by appropriately setting the modulation pattern displayed on the liquid crystal layer 76, it is possible to modulate the laser beam L (for example, modulating the intensity, amplitude, phase, polarization, etc. of the laser beam L). Note that the modulation surface 7a shown in Figure 3 is, for example, the liquid crystal layer 76.

[0036] As described above, the laser light L output from the light source 31 is incident on the focusing lens 33 via the spatial light modulator 7 and the 4f lens unit 34, and is focused into the object 11 by the focusing lens 33, thereby forming a modified region 12 and cracks extending from the modified region 12 in the object 11 within the focused region C. Furthermore, by controlling the movement units 4 and 5 of the control unit 6, the focused region C is moved relative to the object 11, thereby forming the modified region 12 and cracks along the direction of movement of the focused region C.

[0037] [Explanation of findings regarding oblique crack formation] Here, the direction of relative movement of the focusing region C at this time (processing progress direction) is defined as the X direction. The direction that intersects (is perpendicular to) the first surface 11a, which is the incident surface of the laser beam L on the object 11, is defined as the Z direction. The direction that intersects (is perpendicular to) the X direction and the Z direction is defined as the Y direction. The X direction and the Y direction are directions along the first surface 11a. Note that the Z direction may also be defined as the optical axis of the focusing lens 33, or the optical axis of the laser beam L focused toward the object 11 via the focusing lens 33.

[0038] As shown in Figures 5(a) and 5(b), there is a requirement to form a crack obliquely along a line RA that is inclined with respect to the Z and Y directions (in this case, a line RA that is inclined from the Y direction at a predetermined angle θ) within an intersecting surface (YZ plane S including the Y and Z directions) that intersects the X direction, which is the machining direction. The inventor's knowledge regarding the formation of such oblique cracks will be explained with reference to machining examples.

[0039] Here, modified regions 12a and 12b are formed as the modified region 12. This connects the crack 13a extending from modified region 12a and the crack 13b extending from modified region 12b, forming a crack 13 that extends diagonally along line RA. Here, first, as shown in Figure 6, a focusing region C1 is formed with the first surface 11a of the object 11 as the laser beam incident surface. On the other hand, a focusing region C2 is formed on the first surface 11a side of focusing region C1, with the first surface 11a as the laser beam incident surface. At this time, focusing region C2 is shifted by a distance Sz in the Z direction from focusing region C1, and by a distance Sy in the Y direction from focusing region C1. Distances Sz and Sy correspond, for example, to the inclination of line RA.

[0040] On the other hand, as shown in Figure 7, by modulating the laser light L using the spatial light modulator 7, the beam shape of the focusing region C (at least focusing region C2) within the YZ plane S is made into an inclined shape that is inclined in the direction of shift with respect to the Z direction (here, the negative side of the Y direction) at least on the side of the first plane 11a from the center Ca of the focusing region C. In the example in Figure 7, the beam is inclined on the negative side of the Y direction with respect to the Z direction on the side of the first plane 11a from the center Ca, and also on the side opposite the first plane 11a from the center Ca, and is an arc shape that is inclined on the negative side of the Y direction with respect to the Z direction. The beam shape of the focusing region C within the YZ plane S is the intensity distribution of the laser light L in the focusing region C within the YZ plane S.

[0041] In this way, by shifting at least two focusing regions C1 and C2 in the Y direction and making the beam shape of at least focusing region C2 (in this case both focusing regions C1 and C2) inclined, a crack 13 extending diagonally can be formed as shown in Figure 9(a). Alternatively, for example, the laser beam L may be split by controlling the modulation pattern of the spatial light modulator 7 to simultaneously form focusing regions C1 and C2 and create the modified region 12 and crack 13 (multifocal processing), or the modified region 12a and crack 13a may be formed by forming focusing region C1, and then the modified region 12b and crack 13b may be formed by forming focusing region C2 (single-pass processing). Furthermore, by forming another focusing region between focusing region C1 and focusing region C2, another modified region 12c may be interposed between modified region 12a and modified region 12b, as shown in Figure 9(b), to create a longer, diagonally extending crack 13.

[0042] Next, we will explain the knowledge required to make the beam shape of the focusing region C in the YZ plane S inclined shape. First, we will specifically explain the definition of the focusing region C. Here, the focusing region C is the region within a predetermined range from the center Ca (for example, a range of ±25 μm from the center Ca in the Z direction). As mentioned above, the center Ca is the position where the beam intensity is highest, or the centroid of the beam intensity. The centroid of the beam intensity is the position where the centroid of the beam intensity is located on the optical axis of the laser beam L when modulation is not performed by a modulation pattern that shifts the optical axis of the laser beam L, such as a modulation pattern for splitting the laser beam L.

[0043] To make the beam shape in the focusing region C tilted, one method is to offset the modulation pattern. More specifically, the spatial light modulator 7 displays various patterns such as a distortion correction pattern for correcting wavefront distortion, a grating pattern for splitting the laser beam, a slit pattern, an astigmatism pattern, a coma aberration pattern, and a spherical aberration correction pattern (a pattern in which these are superimposed is displayed). Of these, as shown in Figure 8, the beam shape in the focusing region C can be adjusted by offsetting the spherical aberration correction pattern Ps.

[0044] In the example of FIG. 8, on the modulation plane 7a, the center Pc of the spherical aberration correction pattern Ps is offset by an offset amount Oy1 to the negative side in the Y direction with respect to the center Lc of the laser beam L (of the beam spot). As described above, the modulation plane 7a is imaged onto the entrance pupil plane 33a of the condenser lens 33 by the 4f lens unit 34. Therefore, the offset on the modulation plane 7a becomes an offset to the positive side in the Y direction on the entrance pupil plane 33a. That is, on the entrance pupil plane 33a, the center Pc of the spherical aberration correction pattern Ps is offset by an offset amount Oy2 to the positive side in the Y direction from the center Lc of the laser beam L and the center of the entrance pupil plane 33a (which coincides with the center Lc here).

[0045] By offsetting the spherical aberration correction pattern Ps in this way, the beam shape of the condensing region C of the laser beam L is deformed into an arc-shaped inclined shape as shown in FIG. 7. Offsetting the spherical aberration correction pattern Ps as described above is equivalent to imparting coma aberration to the laser beam L. Therefore, by including a coma aberration pattern for imparting coma aberration to the laser beam L in the modulation pattern of the spatial light modulator 7, the beam shape of the condensing region C may be an inclined shape. Note that as the coma aberration pattern, a pattern corresponding to the 9th term of the Zernike polynomial (the Y component of the third-order coma aberration) and generating coma aberration in the Y direction can be used.

[0046] [Example of Trimming Process] Subsequently, an example of the trimming process will be described. The trimming process is a process of removing unnecessary portions from the object 11. The trimming process includes a laser processing method in which the laser beam L is irradiated onto the object 11 with the condensing region aligned therewith, thereby forming a modified region 12 in the object 11. The object 11 includes, for example, a semiconductor wafer formed in a disk shape. The object is not particularly limited and may be formed of various materials or may have various shapes. A functional element (not shown) is formed on the second surface 11b, which is the opposite surface of the object 11 to the laser beam incident surface. The functional element is, for example, a light receiving element such as a photodiode, a light emitting element such as a laser diode, a circuit element such as a memory, or the like.

[0047] FIGS. 10, 11(a) and 11(b) are views showing the object 11. As shown in FIGS. 10, 11(a) and 11(b), an effective region R and a removal region E are set in the object 11. The effective region R is a portion corresponding to the semiconductor device to be obtained. The effective region R here is a disk-shaped portion including the central portion when the object 11 is viewed from the thickness direction. The removal region E is a region outside the effective region R in the object 11. The removal region E is an outer edge portion other than the effective region R in the object 11. The removal region E here is an annular portion surrounding the effective region R. The removal region E includes a peripheral portion (bevel portion of the outer edge) when the object 11 is viewed from the thickness direction. The setting of the effective region R and the removal region E can be performed in the control unit 6. The effective region R and the removal region E may be specified by coordinates.

[0048] The stage 2 is a support portion on which the object 11 is placed. In the stage 2 of the present embodiment, the object 11 is placed in a state where the first surface 11a of the object 11 is on the upper side, which is the laser beam incident surface side (the second surface 11b is on the lower side, which is the stage 2 side). The stage 2 has a rotation axis Cx provided at its center. The rotation axis Cx is an axis extending along the Z direction. The stage 2 is rotatable about the rotation axis Cx. The stage 2 is rotationally driven by the driving force of a known driving device such as a motor.

[0049] The irradiation unit 3 irradiates the object 11 placed on the stage 2 with laser light L along the Z direction, forming a modified region inside the object 11. The irradiation unit 3 is attached to the moving unit 5. The irradiation unit 3 is linearly movable in the Z direction by the driving force of a known drive device such as a motor. The irradiation unit 3 is linearly movable in the X and Y directions by the driving force of a known drive device such as a motor.

[0050] As described above, the irradiation unit 3 is equipped with a spatial light modulator 7. The spatial light modulator 7 constitutes a shaping unit that shapes the shape of the focusing region C in a plane perpendicular to the optical axis of the laser beam L (i.e., the shape of the focusing region C when viewed from the Z direction) (hereinafter also referred to as the "beam shape"). The spatial light modulator 7 can shape the laser beam L such that the beam shape has a longitudinal direction when viewed from the Z direction, and that this longitudinal direction intersects the processing direction. For example, the spatial light modulator 7 shapes the beam shape into an elliptical shape by displaying a modulation pattern that makes the beam shape elliptical.

[0051] The beam shape is not limited to an elliptical shape, but can be any elongated shape. The beam shape may be a flattened circle, an oval, or a track shape. The beam shape may be an elongated triangle, rectangle, or polygon. The modulation pattern of the spatial light modulator 7 that realizes such a beam shape may include at least one of a slit pattern and an astigmatism pattern. If the laser light L has multiple focusing regions C due to astigmatism or the like, the shape of the focusing region C furthest upstream in the optical path of the laser light L is the beam shape of this embodiment (the same applies to other laser lights). The longitudinal direction here is the major axis direction of the elliptical shape related to the beam shape, and is also called the elliptical major axis direction.

[0052] The beam shape is not limited to the shape of the focal point, but may also be the shape near the focal point; in short, it should be the shape of a part of the focal region C. For example, in the case of a laser beam L with astigmatism, as shown in Figure 12(a), the beam shape has a longitudinal direction NH in the region on the laser beam incident surface side near the focal point. In the beam intensity distribution within the plane of the beam shape in Figure 12(a) (within the plane at the Z-direction position on the laser beam incident surface side near the focal point), the distribution has a strong intensity in the longitudinal direction NH, and the direction of strong beam intensity coincides with the longitudinal direction NH.

[0053] In the case of a laser beam L with astigmatism, as shown in Figure 12(c), in the region on the opposite side of the laser beam incident surface near the focal point, the beam shape has a longitudinal direction NH0 perpendicular to the longitudinal direction NH of the region on the laser beam incident surface side (see Figure 12(a)). In the beam intensity distribution within the plane of the beam shape in Figure 12(c) (within the plane at the Z-direction position on the opposite side of the laser beam incident surface near the focal point), the distribution has a strong intensity in the longitudinal direction NH0, and the direction of strong beam intensity coincides with the longitudinal direction NH0. In the case of a laser beam L with astigmatism, as shown in Figure 12(b), in the region between the laser beam incident surface side and the opposite side near the focal point, the focal region C is circular and does not have a longitudinal direction.

[0054] In the case of a laser beam L having such astigmatism, the focusing region C targeted by this embodiment includes the region on the laser beam incident surface side near the focusing point, and the beam shape targeted by this embodiment is the beam shape shown in Figure 12(a).

[0055] Furthermore, by adjusting the modulation pattern of the spatial light modulator 7, the position in the focusing region C where the beam shape shown in Figure 12(a) is obtained can be controlled as desired. For example, it can be controlled so that the beam shape shown in Figure 12(a) is obtained in the region on the opposite side of the laser light incident surface near the focusing point. Alternatively, for example, it can be controlled so that the beam shape shown in Figure 12(a) is obtained in the region between the laser light incident surface and the opposite side near the focusing point. The position of a part of the focusing region C is not particularly limited and can be any position between the laser light incident surface and the opposite surface of the object 11.

[0056] Furthermore, for example, when a modulation pattern is controlled and / or a slit or elliptical optical system is used by a mechanical mechanism, as shown in Figure 13(a), the beam shape has a longitudinal direction NH in the region on the laser light incident surface side near the focal point. In the beam intensity distribution within the plane of the beam shape in Figure 13(a) (within the plane at the Z-direction position on the laser light incident surface side near the focal point), the distribution has a strong intensity in the longitudinal direction NH, and the direction of strong beam intensity coincides with the longitudinal direction NH.

[0057] When a slit or elliptical optical system is used, as shown in Figure 13(c), in the region on the opposite side of the laser beam incident surface near the focal point, the beam shape has the same longitudinal direction NH as the region on the laser beam incident surface side (see Figure 12(a)). In the beam intensity distribution within the plane of the beam shape in Figure 13(c) (in the plane at the Z-direction position on the opposite side of the laser beam incident surface near the focal point), the distribution has a strong intensity in the longitudinal direction NH, and the direction of strong beam intensity coincides with the longitudinal direction NH. When a slit or elliptical optical system is used, as shown in Figure 13(b), at the focal point, the beam shape has a longitudinal direction NH0 perpendicular to the longitudinal direction NH of the region on the laser beam incident surface side (see Figure 13(a)). In the beam intensity distribution within the plane of the beam shape in Figure 13(b) (in the plane at the Z-direction position of the focal point), the distribution has a strong intensity in the longitudinal direction NH0, and the direction of strong beam intensity coincides with the longitudinal direction NH0.

[0058] When such a slit or elliptical optical system is used, the beam shape other than the focal point has a longitudinal direction, and the beam shape other than the focal point is the beam shape targeted by this embodiment. That is, a part of the focal region C targeted by this embodiment includes the region on the laser light incident surface side near the focal point, and the beam shape targeted by this embodiment is the beam shape shown in Figure 13(a).

[0059] In the trimming process, the control unit 6 controls the rotation of the stage 2, the irradiation of laser light L from the irradiation unit 3, the beam shape, and the movement of the focusing area C. The control unit 6 can perform various controls based on rotation information (hereinafter also referred to as "θ information") related to the amount of rotation of the stage 2. The θ information may be obtained from the drive amount of the drive device that rotates the stage 2, or it may be obtained by a separate sensor or the like. The θ information can be obtained by various known methods. The θ information here includes the rotation angle based on the state when the object 11 is located in the 0° direction.

[0060] The control unit 6 rotates the stage 2 and positions the focusing area C along line A (the periphery of the effective area R) on the object 11. Based on θ information, it controls the start and stop of irradiation of the laser beam L from the irradiation unit 3 to perform peripheral processing to form a modified area along the periphery of the effective area R. Without rotating the stage 2, the control unit 6 irradiates the removal area E with the laser beam L and moves the focusing area C of the laser beam L to perform removal processing to form a modified area in the removal area E. The control unit 6 controls at least one of the rotation of the stage 2, the irradiation of the laser beam L from the irradiation unit 3, and the movement of the focusing area C so that the pitch of the multiple modified spots included in the modified area (the distance between adjacent modified spots in the processing direction) remains constant. The control unit 6 obtains the reference position (position in the 0° direction) of the object 11 in the rotation direction and the diameter of the object 11 from the image captured by the alignment camera (not shown). The control unit 6 controls the movement of the irradiation unit 3 so that it can move along the X direction up to the rotation axis Cx of the stage 2.

[0061] Next, an example of trimming will be described. First, the object 11 is placed on the stage 2 so that the first surface 11a becomes the incident surface of the laser beam L. The second surface 11b of the object 11, on which the functional elements are mounted, is protected by being adhered to a support substrate or tape material.

[0062] Next, trimming is performed. In trimming, the control unit 6 performs peripheral edge processing. Specifically, as shown in Figure 14(a), while rotating the stage 2 at a constant speed, the focusing area C is positioned along the periphery of the effective area R on the object 11, and the start and stop of irradiation of the laser beam L in the irradiation unit 3 is controlled based on θ information. As a result, as shown in Figures 14(b) and 14(c), a modified area 12 is formed along line A (periphery of the effective area R). The formed modified area 12 includes modified spots and cracks extending from the modified spots.

[0063] In the trimming process, the control unit 6 performs the removal process. Specifically, as shown in Figure 15(a), without rotating the stage 2, the laser beam L is irradiated in the removal area E, and the irradiation unit 3 is moved along the X direction, so that the focusing area C of the laser beam L is moved relative to the object 11 in the X direction. After rotating the stage 2 by 90°, the laser beam L is irradiated in the removal area E, and the irradiation unit 3 is moved along the X direction, so that the focusing area C of the laser beam L is moved relative to the object 11 in the X direction.

[0064] As a result, as shown in Figure 15(b), a modified region 12 is formed along lines extending in the Z direction to divide the removal region E into four equal parts. The formed modified region 12 includes modified spots and cracks extending from the modified spots. These cracks may reach at least one of the first surface 11a and the second surface 11b, or they may not reach at least one of the first surface 11a and the second surface 11b. Subsequently, as shown in Figures 16(a) and 16(b), the removal region E is removed using, for example, a jig or air, with the modified region 12 as the boundary. This forms a semiconductor device 11K from the object 11. Next, as shown in Figure 16(c), the first surface 11a of the semiconductor device 11K is ground to an arbitrary thickness. As a result, a semiconductor device 11M is obtained.

[0065] Next, the trimming process will be explained in more detail. As shown in Figure 17, the object 11 is plate-shaped. The object 11 has a crystal structure that includes a (100) plane, one (110) plane, another (110) plane, a first crystal orientation K1 perpendicular to one (110) plane, and a second crystal orientation K2 perpendicular to the other (110) plane. The first plane 11a of the object 11 is the (100) plane. The object 11 is supported on the stage 2 such that the (100) plane (i.e., the first plane 11a) is the incident plane of the laser beam L. The object 11 is, for example, a silicon wafer made of silicon. The (110) plane is a cleavage plane. The first crystal orientation K1 and the second crystal orientation K2 are the directions in which cracks are most likely to extend in the cleavage direction, i.e., the Z direction. The first crystal orientation K1 and the second crystal orientation K2 are orthogonal to each other.

[0066] The object 11 is provided with an alignment target 11n. For example, the alignment target 11n has a certain relationship with respect to the position of the object 11 in the 0° direction in the θ direction (the rotation direction around the rotation axis Cx of the stage 2). The position in the 0° direction is the reference position of the object 11 in the θ direction. For example, the alignment target 11n is a notch formed on the outer edge. Note that the alignment target 11n is not particularly limited and may be an orientation flat of the object 11 or a pattern of a functional element. In the illustrated example, the alignment target 11n is provided at the position of the object 11 in the 0° direction. In other words, the alignment target 11n is provided at a position where the outer edge of the object 11 and the second crystal orientation K2 are perpendicular.

[0067] A line A is set on the object 11 as a trimming line. Line A is the line where the modified region 12 is to be formed. Line A extends in an annular shape inside the outer edge of the object 11. Here, line A extends in an annular shape. Line A is set at the boundary between the effective region R and the removal region E of the object 11. The setting of line A can be done in the control unit 6. Line A is a virtual line, but it may also be an actually drawn line. Line A may also be specified by coordinates. Line A is a line set on the virtual surface M0, which will be described later.

[0068] The control unit 6 acquires object information relating to the object 11. The object information includes, for example, information relating to the crystal orientation of the object 11 (first crystal orientation K1 and second crystal orientation K2), and alignment information relating to the position of the object 11 in the 0° direction and the diameter of the object 11. The control unit 6 can acquire object information based on images captured by the alignment camera, as well as input from user operation or external communication.

[0069] Furthermore, the control unit 6 acquires line information related to line A. The line information includes information about line A, and information regarding the direction of movement (also called the "processing direction") when the light-gathering region C is moved relative to line A. For example, the processing direction is the tangential direction of line A passing through the light-gathering region C located on line A. The control unit 6 can acquire line information based on user operation or input from external communication, etc.

[0070] Furthermore, based on the acquired object information and line information, the control unit 6 determines the orientation of the longitudinal direction when the focusing region C is moved relatively along line A such that the longitudinal direction of the beam shape intersects the processing direction. Specifically, based on the object information and line information, the control unit 6 determines the orientation of the longitudinal direction NH into a first orientation and a second orientation. The first orientation is the longitudinal direction of the beam shape when the focusing region C is moved relatively along the first region A1 of line A. The second orientation is the longitudinal direction of the beam shape when the focusing region C is moved relatively along the second region A2 of line A. Hereinafter, "longitudinal direction of the beam shape" will also be simply referred to as "orientation of the beam shape".

[0071] The first region A1 is an arc-shaped region, and for example, when the point where the second crystal orientation K2 and line A intersect is 0°, the point where the first crystal orientation K1 and line A intersect is 90°, and the point midway between 0° and 90° on line A is 45°, it includes the region from 0° to 45°, the region from 90° to 135°, the region from 180° to 225°, and the region from 270° to 315°. The second region A2 is an arc-shaped region, and includes the region from 45° to 90°, the region from 135° to 180°, the region from 225° to 270°, and the region from 315° to 360°. In this case, the 45° point and the 225° point are the points where the third crystal orientation K3, which is perpendicular to the (100) plane, intersects with line A, and the 135° point and the 315° point are the points where the fourth crystal orientation K4, which is perpendicular to the (100) plane, intersects with line A.

[0072] Thus, line A includes a plurality of first regions A1 and a plurality of second regions A2 arranged alternately at 45° intervals counterclockwise. However, the above angular range of the first regions A1 and second regions A2 can be arbitrarily changed depending on where the 0° point is set. For example, if the point where the first crystal orientation K1 and line A are orthogonal is set to 0° (i.e., the 90° point is set to 0°), then the angular range of the first regions A1 and second regions A2 will be rotated by 90° from the above angular range. Also, if the 0° point is set as described above, the point at 315°, which is rotated by 45° clockwise from the 0° point, can be rephrased as the -45° point. Furthermore, the boundary point between the first region A1 and the second region A2 (e.g., 45°) may be included in either the first region A1 or the second region A2, or in both.

[0073] The first region A1 includes a region where, when the focusing region C is moved relatively along line A, the processing angle described later is between 0° and 45°, or between -90° and -45°. The second region A2 includes a region where, when the focusing region C is moved relatively along line A, the processing angle described later is between 45° and less than 90°, or between -45° and less than 0°.

[0074] As shown in Figure 18(b), the processing angle α is the angle of the processing direction ND with respect to the first crystal orientation K1. The processing angle α is defined as a positive angle when viewed from the Z direction intersecting the first surface 11a, which is the incident surface of the laser beam L, with counterclockwise angles being positive and clockwise angles being negative. The processing angle α can be obtained based on the θ information, object information, and line information of stage 2. When the focusing area C is moved relatively along the first region A1, for example, the processing angle α can be recognized as being between 0° and 45° or between -90° and -45°. When the focusing area C is moved relatively along the second region A2, for example, the processing angle α can be recognized as being between 45° and 90° or between -45° and 0°.

[0075] The first and second orientations are directions that are inclined with respect to the machining direction ND, such that they approach the direction with the larger angle (the one that is further away) between the first crystal orientation K1 and the second crystal orientation K2 and the machining direction ND.

[0076] The first and second orientations are as follows when the machining angle α is 0° or more and 90° or less. The first orientation is the direction in which the longitudinal direction NH is inclined with respect to the machining direction ND toward the side approaching the second crystal orientation K2. The second orientation is the direction in which the longitudinal direction NH is inclined with respect to the machining direction ND toward the side approaching the first crystal orientation K1. For example, the first orientation is the direction inclined 10° to 35° toward the side approaching the second crystal orientation K2 from the machining direction ND. For example, the second orientation is the direction inclined 10° to 35° toward the side approaching the first crystal orientation K1 from the machining direction ND.

[0077] The first orientation is the orientation of the focusing region C when the beam angle β is between +10° and +35°. The second orientation is the orientation of the focusing region C when the beam angle β is between -35° and -10°. The beam angle β is the angle between the processing direction ND and the longitudinal direction NH. The beam angle β is defined as a positive angle when viewed from the Z direction intersecting the first surface 11a, which is the incident surface of the laser beam L, and a negative angle when viewed counterclockwise. The beam angle β can be obtained based on the orientation of the focusing region C and the processing direction ND.

[0078] The control unit 6 controls the start and stop of laser processing on the object 11. The control unit 6 performs a first processing operation in which it moves the focusing area C relatively along the first area A1 of line A to form a modified area 12, and stops the formation of modified areas 12 in areas other than the first area A1 of line A. The control unit 6 performs a second processing operation in which it moves the focusing area C relatively along the second area A2 of line A to form a modified area 12, and stops the formation of modified areas 12 in areas other than the second area A2 of line A.

[0079] The control unit 6 can switch the formation and cessation of the modified region 12 as follows. For example, the irradiation unit 3 can switch the formation and cessation of the formation of the modified region 12 by switching the start and stop (ON / OFF) of the irradiation (output) of the laser light L. Specifically, if the laser oscillator is composed of a solid-state laser, the start and stop of the irradiation of the laser light L can be switched at high speed by switching the ON / OFF of a Q switch (AOM (acousto-optic modulator), EOM (electro-optic modulator), etc.) provided in the resonator. If the laser oscillator is composed of a fiber laser, the start and stop of the irradiation of the laser light L can be switched at high speed by switching the ON / OFF of the output of the semiconductor lasers constituting the seed laser and amplifier (excitation) laser. If the laser oscillator uses an external modulation element, the ON / OFF of the irradiation of the laser light L can be switched at high speed by switching the ON / OFF of an external modulation element (AOM, EOM, etc.) provided outside the resonator.

[0080] Alternatively, the control unit 6 may switch between forming and stopping the modified region 12 as follows: For example, the optical path of the laser beam L may be opened and closed by controlling a mechanical mechanism such as a shutter, thereby switching between forming and stopping the modified region 12. The formation of the modified region 12 may be stopped by switching the laser beam L to CW light (continuous wave). The formation of the modified region 12 may be stopped by displaying a pattern (for example, a textured pattern that causes laser scattering) on ​​the liquid crystal layer 76 of the spatial light modulator 7 that prevents the focusing state of the laser beam L from being modified. The formation of the modified region 12 may be stopped by controlling an output adjustment unit such as an attenuator to reduce the output of the laser beam L to a level that prevents the formation of the modified region 12. The formation of the modified region 12 may be stopped by switching the polarization direction. The formation of the modified region 12 may be stopped by scattering (skipping) the laser beam L in a direction other than the optical axis.

[0081] The control unit 6 adjusts the orientation of the focusing region C by controlling the spatial light modulator 7. When executing the first processing process, the control unit 6 adjusts the orientation of the focusing region C to be in the first orientation. When executing the second processing process, the control unit 6 adjusts the orientation of the focusing region C to be in the second orientation. As an example, the control unit 6 adjusts the longitudinal direction NH of the focusing region C so that it changes within a range of ±35° with respect to the processing direction ND.

[0082] The laser processing apparatus 1 described above performs the following trimming process. First, the stage 2 is rotated and the irradiation unit 3 on which the camera is mounted is moved along the X and Y directions so that the alignment camera is positioned directly above the alignment target 11n of the object 11 and the camera is in focus on the alignment target 11n.

[0083] Next, imaging is performed using an alignment camera. Based on the image captured by the camera, the position of the object 11 in the 0° direction is obtained. The control unit 6 acquires object information and line information based on the image captured by the camera, as well as input from user operation or external communication. The object information includes alignment information regarding the position and diameter of the object 11 in the 0° direction. As described above, since the alignment target 11n has a certain relationship in the θ direction with respect to the position in the 0° direction, the position in the 0° direction can be obtained by obtaining the position of the alignment target 11n from the image captured. The diameter of the object 11 can be obtained based on the image captured by the camera. The diameter of the object 11 may be set by user input.

[0084] Next, based on the acquired object information and line information, the control unit 6 determines a first and second orientation as the longitudinal direction NH of the focusing area C when moving the focusing area C relatively along line A. Then, the stage 2 is rotated to position the object 11 at the 0° direction. The irradiation unit 3 is moved along the X and Y directions so that the focusing area C is positioned at a predetermined trimming position in the X direction. For example, the predetermined trimming position is a predetermined position on line A on the object 11.

[0085] Next, the rotation of stage 2 is started. Tracking of the first surface 11a by a distance measuring sensor (not shown) is started. Before starting tracking by the distance measuring sensor, it is confirmed in advance that the position of the focusing area C is within the range of measurement possible by the distance measuring sensor. When the rotation speed of stage 2 becomes constant (uniform speed), irradiation of laser light L by the irradiation unit 3 is started. While rotating stage 2, the control unit 6 switches the irradiation of laser light L ON / OFF, so that the focusing area C is moved relatively along the first area A1 of line A to form a modified area 12, as shown in Figure 18(a), and the formation of modified areas 12 in areas of line A other than the first area A1 is stopped (first area processing step). As shown in Figure 18(b), when the first area processing step is performed, the control unit 6 adjusts the orientation of the focusing area C to be in the first orientation. In other words, the orientation of the focusing area C in the first area processing step is fixed in the first orientation.

[0086] Next, while rotating stage 2, the control unit 6 switches the irradiation of laser light L ON / OFF, so that the focusing region C is moved relatively along the second region A2 of line A, as shown in Figure 19(a), to form a modified region 12, and the formation of modified regions 12 in areas of line A other than the second region A2 is stopped (second region processing step). As shown in Figure 19(b), when the second region processing step is performed, the control unit 6 adjusts the orientation of the focusing region C so that it is in the second orientation. In other words, the orientation of the focusing region C in the second region processing step is fixed in the second orientation. The first and second region processing steps described above are repeated by changing the position in the Z direction of the trimming predetermined position. As a result, multiple rows of modified regions 12 are formed in the Z direction along line A at the periphery of the effective region R inside the object 11.

[0087] [First Embodiment] The first embodiment will now be described. In the first embodiment, similar to the laser processing described above, the laser beam L is shaped so that the beam shape has a longitudinal direction and this longitudinal direction intersects the processing direction. Specifically, in the first embodiment, the first and second region processing steps, in which the orientation of the beam shape is the first and second orientations, are repeated by changing the position in the Z direction of the predetermined trimming position. In the following description, this point will be omitted as appropriate.

[0088] Figure 20 shows a laser-processed object 100 according to the first embodiment. Figure 20(a) is a plan view, and Figure 20(b) is a side view. As shown in Figures 20(a) and 20(b), the object 100 is a so-called bonded wafer and includes the object 11 described above and an object (another object) 11R which is a separate component from object 11. Object 11R is, for example, a silicon wafer. Object 11 includes a plurality of functional elements and includes a device layer 110 formed on the second surface 11b. Object 11R includes a plurality of functional elements and includes a device layer 110R formed on the first surface 11Ra of object 11R. Object 11 and object 11R are bonded together by arranging the device layer 110 and the device layer 110R so that they face each other and joining them together, thus constituting the object 100. The surface on which the device layer 110 and the device layer 110R are bonded together is called the bonding surface.

[0089] A virtual surface M0 is set on the object 11. The virtual surface M0 includes a first planned surface M1 which is set to be an annular shape with the Z direction as its axis, a second planned surface M2 which is set to be an annular shape with the Z direction as its axis and is continuous with the laser light incident surface side of the first planned surface M1, and a third planned surface M3 which is set to be an annular shape with the Z direction as its axis and is continuous with the laser light incident surface side of the second planned surface M2.

[0090] As shown in Figure 21(a), the first to third planned formation surfaces M1 to M3 are surfaces where the modified region 12 and cracks extending from the modified region 12 are planned to form. In other words, the modified region 12 and cracks are planned to form along the first to third planned formation surfaces M1 to M3. The first to third planned formation surfaces M1 to M3 are coaxial, annular, hypothetical surfaces. The line A described above is set on the first to third planned formation surfaces M1 to M3. In other words, line A is set along the first to third planned formation surfaces M1 to M3.

[0091] The first planned surface to be formed M1 is a surface that constitutes the circumferential surface of a frustoconical shape. In the illustrated example, the first planned surface to be formed M1 is set on the part of the object 11 on the side of the second surface 11b. The second planned surface to be formed M2 is a surface that constitutes the circumferential surface of a frustoconical shape. In the illustrated example, the second planned surface to be formed M2 is set on the object 11 closer to the second surface 11b than the center in the Z direction. The third planned surface to be formed M3 is a surface that is aligned with the Z direction and is cylindrical. In the illustrated example, the third planned surface to be formed M3 is set on the part of the object 11 from the center in the Z direction to the first surface 11a. The third planned surface to be formed M3 is also set at the boundary between the effective area R and the removal area E of the object 11.

[0092] The virtual plane M0 can be set in the control unit 6. Information regarding the virtual plane M0 may be recorded in the control unit 6. Information regarding the virtual plane M0 can be obtained based on user operation or input from external communication. The virtual plane M0 may be specified by coordinates.

[0093] The inclination angle θ2 of the second planned surface M2 with respect to the Z direction is greater than the inclination angle θ1 of the first planned surface M1 with respect to the Z direction. In other words, the inclination angle θ1 of the first planned surface M1 with respect to the Z direction is smaller than the inclination angle θ2 of the second planned surface M2 with respect to the Z direction. That is, the first planned surface M1 extends more linearly in the Z direction than the second planned surface M2. The second planned surface M2 bends and extends from the end of the first planned surface M1 toward the first surface 11a, so as to bend inward toward the object 11 (towards the center of the object 11). As an example, the inclination angle θ2 of the second planned surface M2 with respect to the Z direction may be 1.5 times or more greater than the inclination angle of the first planned surface M1 with respect to the Z direction.

[0094] The control unit 6 performs a first processing process, which involves laser processing along the first planned surface M1; a second processing process, which involves laser processing along the second planned surface M2; and a third processing process, which involves laser processing along the third planned surface M3.

[0095] In the first processing step, laser processing is performed under first processing conditions with the aim of forming a modified region 12 and ensuring that the cracks 13 extending from the modified region 12 follow the first planned surface M1. In the second processing step, laser processing is performed under second processing conditions with the aim of forming a modified region 12 and ensuring that the cracks 13 extending from the modified region 12 follow the second planned surface M2. In the third processing step, laser processing is performed under third processing conditions with the aim of forming a modified region 12 and ensuring that the cracks extending from the modified region 12 follow the third planned surface M3.

[0096] The first processing condition is for extending a crack from the modified region 12 along the first planned surface M1. The first processing condition is for forming the oblique crack along the first planned surface M1. The second processing condition is for extending a crack from the modified region 12 along the second planned surface M2. The second processing condition is for forming the oblique crack along the second planned surface M2. The first and second processing conditions are for imparting coma aberration to the laser beam L. The second processing condition is for imposing a stronger coma aberration on the laser beam L compared to the first processing condition. The third processing condition is for extending a crack from the modified region 12 along the third planned surface M3. The third processing condition is a normal laser processing condition for forming a crack along the third planned surface M3. The third processing condition is for not imparting coma aberration to the laser beam L.

[0097] In the first, second, and third processing steps, the laser beam L is modulated according to the modulation pattern. The first processing condition is one in which a first modulation pattern is used as the modulation pattern, which imparts a first coma aberration to the laser beam L. The second processing condition is one in which a second modulation pattern is used as the modulation pattern, which imparts a second coma aberration to the laser beam L that is stronger than the intensity of the first coma aberration. The first and second modulation patterns are modulation patterns that include the above coma aberration patterns. The third processing condition is one in which a third modulation pattern is used as the modulation pattern, which does not include the coma aberration pattern.

[0098] Next, a method for manufacturing a semiconductor device, including a laser processing method according to the first embodiment, will be described. In the following description, explanations similar to those given above regarding the laser processing will be omitted.

[0099] As a trimming process, laser processing is performed along the first planned surface M1 using the laser processing device 1 (first processing step). Specifically, as shown in Figure 21(b), laser processing is performed under first processing conditions along the first planned surface M1 to form a modified region 12A and oblique cracks 13A extending from the modified region 12A. In the illustrated example, a row of modified regions 12A in the Z direction is formed on the object 11 along the first planned surface M1. Also in the illustrated example, the oblique cracks 13A extend to the second surface 11b of the object 11.

[0100] Next, as a trimming process, laser processing is performed along the second planned surface M2 using the laser processing device 1 (second processing step). Specifically, as shown in Figure 22(a), laser processing is performed under second processing conditions along the second planned surface M2 to form modified regions 12B and oblique cracks 13B extending from the modified regions 12B. In the illustrated example, two rows of modified regions 12B are formed on the object 11 along the second planned surface M2 in the Z direction.

[0101] Next, as a trimming process, laser processing is performed along the third planned surface M3 using the laser processing device 1 (third processing step). Specifically, as shown in Figure 22(b), laser processing is performed under the third processing conditions along the third planned surface M3 to form a modified region 12C and a crack 13C extending from the modified region 12C along the Z direction. In the illustrated example, two rows of modified regions 12C are formed on the object 11 along the second planned surface M2 in the Z direction. The crack 13C reaches the first surface 11a of the object 11.

[0102] Next, external stress is applied to the object 11, cutting the object 11 with the modified region 12 and cracks 13 extending across the virtual surface M0 as the boundary, and peeling off at least a portion of the peripheral portion (removal region E) of the object 11 (peeling step). Subsequently, as shown in Figure 23, a grinding device 50 such as a grinder is used to grind and remove the grinding region from the first surface 11a to a predetermined depth on the object 11 (removal step). This obtains the semiconductor device 11M. The grinding region is the area on the object 11 from the laser beam incident surface to a depth including the second planned formation surface M2. The removal of the object 11 in the removal step is not limited to being achieved by grinding using the grinding device 50, but may also be achieved by slicing using laser light.

[0103] After the removal process, the semiconductor device 11M (object 11 after the removal process) is divided into multiple chips (division process). In the division process, any method can be used to divide (cut) the semiconductor device 11M, such as laser dicing, blade dicing, and plasma dicing. This completes the manufacturing method of the semiconductor device.

[0104] As described above, in the laser processing method and laser processing apparatus 1, the laser beam L is shaped such that, when viewed from the Z direction, the focusing region of the laser beam L has a longitudinal direction, and this longitudinal direction intersects with the processing direction ND (see Figures 18 and 19). This makes it possible to suppress the occurrence of twisted hackles on the cut surface, even if there is a discrepancy between the cleavage direction of the object 11 and the cutting direction of the object 11. Furthermore, since the first and second planned formation surfaces M1 and M2 are inclined with respect to the Z direction, oblique cracks 13A and 13B can be formed from the modified regions 12A and 12B by performing laser processing along the first and second planned formation surfaces M1 and M2. For example, stress distribution in the refraction portion between oblique crack 13A and oblique crack 13B, and stress distribution in the refraction portion between oblique crack 13B and crack 13C can suppress the extension of the crack 13, thereby preventing the crack 13 from extending to another object 11R.

[0105] Here, it is found that if the inclination angle θ1 of the first planned formation surface M1 is the same as or greater than the inclination angle θ2 of the second planned formation surface M2 (i.e., if the inclination angle of the oblique crack 13A with respect to the Z direction is large), the above effect of suppressing the occurrence of twisted hackle is weakened, and a situation in which twisted hackle is likely to occur may arise. Therefore, in this embodiment, when the crack 13 is formed along the first and second planned formation surfaces M1 and M2, by making the inclination angle θ2 of the second planned formation surface M2 with respect to the Z direction larger than the inclination angle θ1 of the first planned formation surface M1 with respect to the Z direction, it is possible to suppress the weakening of the effect of suppressing the occurrence of twisted hackle, and the effect can be fully exerted. Accordingly, according to this embodiment, it is possible to suppress the extension of the crack 13 to another object 11R and to suppress the deterioration of the quality of the cut surface.

[0106] Furthermore, observations of the object 11 after laser processing in this embodiment revealed that the generation of twisted hackles was suppressed compared to the object 11 after laser processing when the inclination angle θ1 was the same as the inclination angle θ2 (i.e., the first and second planned formation surfaces M1 and M2 were on the same surface), and when the inclination angle θ1 was greater than or equal to the inclination angle θ2.

[0107] In the laser processing method, the second processing conditions of the second processing step are conditions in which the intensity of coma aberration applied to the laser beam L is stronger than that of the first processing conditions of the first processing step. In this case, it is possible to specifically realize laser processing that forms an oblique crack 13A along the first planned surface M1 and laser processing that forms an oblique crack 13B along the second planned surface M2.

[0108] In the laser processing method, the first processing condition uses a first modulation pattern, and the second processing condition uses a second modulation pattern that imparts a second coma aberration to the laser light L that is stronger than the intensity of the first coma aberration imparted to the laser light L by the first modulation pattern. In this case, the first and second coma aberrations can be imparted to the laser light L by utilizing the modulation patterns.

[0109] In the laser processing method, the virtual surface M0 is a surface along the Z direction and further includes a third planned surface M3 that is continuous with the laser light incident surface side of the second planned surface M2. The laser processing method further includes a third processing step of performing laser processing along the third planned surface M3. In this case, the third processing step can form a modified region 12C and a crack 13C along the Z direction so as to be continuous with the oblique crack 13B along the second planned surface M2. In this case, the removal of the grinding region (object to be removed) in the removal step becomes easier.

[0110] In the laser processing method, the object 11 has a crystal structure that includes a (100) plane, one (110) plane, another (110) plane, a first crystal orientation K1 perpendicular to the one (110) plane, and a second crystal orientation K2 perpendicular to the other (110) plane, with the (100) plane being the laser beam incident plane. The object 11 has an annular line A set on it that includes an arc-shaped first region A1 and an arc-shaped second region A2 having a boundary with respect to the first region A1, as viewed from the Z direction. In the first and second processing steps, the laser beam L is shaped such that the longitudinal direction of the focusing region C is inclined with respect to the processing direction in a direction that approaches the larger of the angles between the first crystal orientation K1 and the second crystal orientation K2 and the processing direction ND.

[0111] In this case, when a crack 13 extending from the modified region 12 is pulled, for example, towards the first crystal orientation K1, the longitudinal direction of the beam shape is not aligned with the direction of processing, but is tilted to approach the second crystal orientation K2, which is on the opposite side of the first crystal orientation K1 relative to the direction of processing. This causes the crack propagation force due to the elongated beam shape to counteract the crack propagation force due to the crystal orientation (crystal axis), allowing the crack 13 to grow precisely along the direction of processing. Similarly, when a crack 13 extending from the modified region 12 is pulled, for example, towards the second crystal orientation K2, the longitudinal direction of the beam shape is not aligned with the direction of processing, but is tilted to approach the first crystal orientation K1, which is on the opposite side of the second crystal orientation K2 relative to the direction of processing. This causes the crack propagation force due to the elongated beam shape to counteract the crack propagation force due to the crystal orientation, allowing the crack 13 to grow precisely along the direction of processing. Therefore, it becomes possible to suppress the deterioration of the quality of the cut surface.

[0112] The laser processing method includes a removal step that removes at least the grinding area of ​​the object 11. In this case, the removal step can remove the portion of the object that includes the oblique crack 13B along the second planned surface M2.

[0113] In the laser processing method, in the first processing step, a row of modified regions 12A is formed on the object 11 along the first planned formation surface M1. In this case, efficient laser processing is possible in the first processing step. Furthermore, it is possible to improve the cycle while maintaining the effect of suppressing the generation of twisted hackles. In addition, in the first processing step, multiple rows of modified regions 12A may be formed along the first planned formation surface M1.

[0114] The method for manufacturing a semiconductor device comprises the first and second processing steps described above, a peeling step in which the object 11 is peeled off along a virtual surface M0 after the first and second processing steps, and a division step in which the object 11 (semiconductor device 11M) is divided into a plurality of chips after the peeling step. In this case as well, since the laser processing method described above is performed, the above-mentioned effects are achieved, which include suppressing the propagation of cracks 13 to another object 11R and suppressing the deterioration of the quality of the cut surface.

[0115] Figure 24 shows the relationship between coma intensity, which is the intensity of coma aberration applied to the laser beam L, and the inclination angle of the oblique crack 13B. The photograph in Figure 24 shows a longitudinal cross-section of the object 11 after laser processing. The straight line shown in the photograph indicates the direction of extension of the oblique crack 13B. As shown in Figure 24, it can be found that the stronger the coma intensity under laser processing conditions, the larger the inclination angle of the oblique crack 13B with respect to the Z direction. In this embodiment, processing conditions are set using this finding.

[0116] In this embodiment, a coma aberration pattern is used as the modulation pattern to impart coma aberration to the laser beam L. However, as described above, coma aberration may also be imparted to the laser beam L by offsetting the modulation pattern. Figure 25 shows the relationship between the offset of the modulation pattern, the inclination angle of the crack 13, and the strength of the coma aberration. Regarding the offset of the modulation pattern, 0 indicates that the center position of the modulation pattern and the center position of the objective lens pupil coincide. The greater the value greater than or less than 0, the further the center position of the modulation pattern and the center position of the objective lens pupil are. The inclination angle of the crack 13 is the inclination angle of the crack 13 with respect to the Z direction. The strength of the coma aberration is the strength of the coma aberration imparted to the laser beam L.

[0117] As shown in Figure 25, the smaller the offset deviation becomes than 0, the more the crack 13 extends to the upper left in the figure (see arrow in the figure) and the greater its inclination angle. The larger the offset deviation becomes than 0, the more the crack 13 extends to the upper right in the figure (see arrow in the figure) and the greater its inclination angle. The smaller the offset deviation becomes than 0, and the larger the offset deviation becomes than 0, the stronger the coma aberration becomes. In this embodiment, coma aberration may be introduced into the laser beam L by offsetting the modulation pattern, utilizing these findings.

[0118] Incidentally, for example, when laser processing is performed on object 11 of object 100, which is a bonded wafer as described above, in the first processing step (first processing treatment), if a weakening region exists on the second surface 11b to which the end of the oblique crack 13A reaches, the oblique crack 13A may be pulled towards the weakening region, and the end of the oblique crack 13A may extend toward the weakening region. In this case, the end of the oblique crack 13A may end up deviating from the first planned formation surface M1. Also, when laser processing is performed on object 11, depending on the condition of the bonded surface, the end of the oblique crack 13A may end up deviating from the first planned formation surface M1. Even in the first processing step in these cases, if the laser processing is performed under first processing conditions that cause the crack 13 to extend from the modified region 12 along the first planned formation surface M1, the crack 13 may end up deviating from the first planned formation surface M1, but this is still included in the first processing step of this embodiment.

[0119] [Second Embodiment] The second embodiment will now be described. In the following, the differences from the first embodiment described above will be explained, and redundant explanations will be omitted.

[0120] As shown in Figure 26(a), the virtual surface M0 of the second embodiment differs from the first embodiment in that it includes a first planned surface M11 that is aligned with the Z direction instead of the first planned surface M1 (see Figure 21(a)). The first planned surface M11 is the surface on which the modified region 12 and the cracks 13 extending from the modified region 12 are planned to be formed. The first planned surface M11 is a virtual annular surface. The first planned surface M11 is a cylindrical surface. The first planned surface M11 is a surface that is aligned with the Z direction. In the virtual surface M0 of the second embodiment as well, the inclination angle θ2 on which the second planned surface M2 is inclined with respect to the Z direction is larger than the inclination angle (=0°) on which the first planned surface M1 is inclined with respect to the Z direction.

[0121] The first processing condition is a normal laser processing condition aimed at forming a crack 13 along the first planned surface M11. The first processing condition is a processing condition that does not impart coma aberration to the laser beam L. The first processing condition is a condition in which a modulation pattern that does not include a coma aberration pattern is used as the modulation pattern.

[0122] In the laser processing method according to the second embodiment, as a trimming process, laser processing is performed along the first to third planned formation surfaces M1 to M3 (first to third processing steps). As a result, modified regions 12A to 12C and cracks 13A to 13C are formed on the object 11, as shown in Figure 26(b). In the first processing step, laser processing is performed along the first planned formation surface M1 under first processing conditions, which are normal laser processing conditions and do not impart coma aberration to the laser beam L, thereby forming the modified region 12A and the cracks 13A extending from the modified region 12A along the Z direction.

[0123] As described above, in this embodiment as well, the above-mentioned effects are achieved, such as suppressing the propagation of the crack 13 to another object 11R and suppressing the deterioration of the quality of the cut surface. Furthermore, in the laser processing method according to this embodiment, the first planned surface M11 is a surface that is aligned in the Z direction. In this case, the crack 13A can be formed along the Z direction by the first processing step. In this case, it is also possible to further suppress the occurrence of twisted hackles.

[0124] [Modifications] The embodiments described above are not limited to the embodiments and modifications described above.

[0125] In the above embodiment, the method for forming the oblique cracks 13A and 13B is not limited to the above, and various other methods may be employed. For example, as a method for forming the oblique cracks 13A and 13B, for example, an asymmetric pattern with a profile that is asymmetrical left to right (or asymmetrical up to down) may be used for the modulation pattern that modulates the laser light L, or an elliptical beam forming pattern in which the ellipticity is changed left to right (or up to down) may be used for forming an elliptical beam with an elliptical beam shape. In addition, for example, as a method for forming the oblique cracks 13A and 13B, a method utilizing an intensity gradient using a long pattern may be used, or a method that adds Trefoil aberration to the modulation pattern may be used.

[0126] In the above embodiment, the removal process involved grinding and removing the material from the laser beam incident surface to a depth including the second planned formation surface M2, but the embodiment is not limited to this. For example, in the removal process, the removal process may involve grinding and removing the material from the laser beam incident surface to a depth including the modified region 12A formed along the first planned formation surface M1, as the grinding region.

[0127] In the above embodiments and modifications, the order of the first processing step, the second processing step, and the third processing step may be arbitrary (not in any particular order). The components in the above embodiments and modifications are not limited to the materials and shapes described above, and various materials and shapes can be applied. Furthermore, the components in the above embodiments and modifications can be arbitrarily applied to the components in other embodiments or modifications. In the above, the term "match" includes not only perfect matches but also approximate matches that allow for measurement errors and manufacturing errors.

[0128] 1...Laser processing device, 2...Stage (support unit), 3...Irradiation unit, 4, 5...Moving unit, 6...Control unit, 7...Spatial light modulator (forming unit), 11...Object, 11a...First surface (laser light incident surface), 11b...Second surface (opposite surface), 11R...Another object, 12, 12A, 12B, 12C...Modification region, 13, 13C...Crack, 13A, 13B...Oblique crack (crack), A1...First region, A2...Second region, C, C1, C2...Focusing region, K1...First crystal orientation, K2...Second crystal orientation, L...Laser light, M0...Virtual plane, M1, M11...First planned formation surface, M2...Second planned formation surface, ND...Processing direction, θ1, θ2...Inclination angle.

Claims

1. A laser processing method for forming a modified region on an object by performing laser processing by irradiating the object with laser light along a virtual surface set on the object, wherein the virtual surface includes a first planned formation surface set to be an annular shape with the Z direction as its axial direction intersecting the laser light incident surface of the object, and a second planned formation surface set to be an annular shape with the Z direction as its axial direction and continuous with the laser light incident surface side of the first planned formation surface, comprising: a first processing step of performing laser processing along the first planned formation surface, and a second processing step of performing laser processing along the second planned formation surface, wherein in the first and second processing steps, the laser light is shaped such that the focusing region of the laser light has a longitudinal direction when viewed from the Z direction, and the longitudinal direction intersects with the processing progress direction which is the direction of movement of the focusing region, and in the first processing step, laser processing is performed under first processing conditions for extending a crack from the modified region along the first planned formation surface. In the second processing step, laser processing is performed under second processing conditions to extend a crack from the modified region along the second planned surface to be formed, and the inclination angle of the second planned surface to be formed with respect to the Z direction is larger than the inclination angle of the first planned surface to be formed with respect to the Z direction.

2. The laser processing method according to claim 1, wherein the second processing condition is a condition in which the intensity of coma aberration imparted to the laser light is stronger than that of the first processing condition.

3. The laser processing method according to claim 2, wherein in the first and second processing steps, the laser light is modulated according to a modulation pattern, the first processing condition uses a first modulation pattern as the modulation pattern, and the second processing condition uses a second modulation pattern that imparts a second coma aberration to the laser light that is stronger than the intensity of the first coma aberration that the first modulation pattern imparts to the laser light.

4. The laser processing method according to any one of claims 1 to 3, wherein the first surface to be formed is a surface along the Z direction.

5. The laser processing method according to any one of claims 1 to 4, wherein the virtual surface further includes a third surface to be formed which is a surface along the Z direction and continuous with the laser light incident surface side of the second surface to be formed, and further comprises a third processing step of performing laser processing along the third surface to be formed.

6. The object has a crystal structure including a (100) plane, a (110) plane, another (110) plane, a first crystal orientation perpendicular to the first (110) plane, and a second crystal orientation perpendicular to the other (110) plane, wherein the (100) plane is the laser beam incident plane, and the object has an annular line set on it, which includes an arc-shaped first region and an arc-shaped second region having a boundary with the first region when viewed from the Z direction, and comprises a first region processing step of forming the modified region on the object along the first region by relatively moving the focusing region along the first region of the line, and a second region processing step of forming the modified region on the object along the second region by relatively moving the focusing region along the second region of the line, and in the first and second region processing steps, The laser processing method according to any one of claims 1 to 5, wherein the laser beam is shaped such that the longitudinal direction of the focusing region is inclined with respect to the processing direction in a direction that approaches the one with the larger angle between the first crystal orientation and the processing direction, among the first and second crystal orientations.

7. The laser processing method according to any one of claims 1 to 6, comprising a removal step of removing at least a region from the laser beam incident surface to a depth including the second planned formation surface in the object.

8. The laser processing method according to any one of claims 1 to 7, wherein in the first processing step, a row of the modified regions is formed on the object along the first planned surface for formation.

9. A method for manufacturing a semiconductor device, comprising: the first and second processing steps included in the laser processing method according to any one of claims 1 to 8; a peeling step performed after the first and second processing steps, in which the object is peeled off along the virtual surface; and a splitting step performed after the peeling step, in which the object is divided into a plurality of chips.

10. A laser processing apparatus for forming a modified region on an object by performing laser processing by irradiating the object with laser light along a virtual surface set on the object, comprising: a support unit for supporting the object; an irradiation unit for irradiating the object supported by the support unit with laser light; a movement unit for moving the laser light focusing region relative to the object; and a control unit for controlling the movement unit and the irradiation unit, wherein the virtual surface includes a first planned formation surface set to be an annular shape with the Z direction as its axial direction intersecting the laser light incident surface of the object, and a second planned formation surface set to be an annular shape with the Z direction as its axial direction and continuous with the laser light incident surface side of the first planned formation surface, the irradiation unit has a forming unit for shaping the laser light such that the focusing region of the laser light has a longitudinal direction when viewed from the Z direction, and the longitudinal direction intersects with the processing progress direction which is the direction of movement of the focusing region, and the control unit performs a first processing process for performing laser processing along the first planned formation surface, and a second processing process for performing laser processing along the second planned formation surface. A laser processing apparatus comprising: a first processing process in which laser processing is performed under first processing conditions such that cracks extending from the modified region are aligned with the first planned formation surface; a second processing process in which laser processing is performed under second processing conditions such that cracks extending from the modified region are aligned with the second planned formation surface; and the inclination angle of the second planned formation surface with respect to the Z direction is greater than the inclination angle of the first planned formation surface with respect to the Z direction.

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