Laser processing apparatus and laser processing method

Abstract

A laser processing apparatus includes: a support unit that supports an object; a light source that emits laser light; a spatial light modulator that modulates the laser light by displaying a modulation pattern; a light condensing unit that condenses the laser light on an object; a drive unit that drives at least one of the support unit and the light collecting unit; and a control unit. The control unit causes a modulation pattern including a trilobal aberration pattern to be displayed on the spatial light modulator such that the beam shape of the laser light at the condensing spot is a beam shape including a central portion and first, second, and third extension portions extending radially from the central portion and having the highest intensity at the central portion. The control unit causes the drive unit to drive at least one of the support unit and the light collecting unit such that the light collecting spot moves relatively along the line.

Description

Technical Field

[0001] The invention relates to a laser processing device and a laser processing method. Background Art

[0002] A laser processing device is known, which includes: a support portion that supports an object; a light source that emits laser light; a spatial light modulator that modulates the laser light emitted from the light source; a focusing portion that focuses the laser light modulated by the spatial light modulator on the object; and an image transfer portion that transfers the image of the laser light in the spatial light modulator to an entrance pupil plane of the focusing portion (for example, refer to Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1; Japanese Patent Application Publication No. 2011-51011 Summary of the invention

[0006] Problems to be solved by the invention

[0007] The laser processing apparatus described above can form a modified region and a crack in an object. Such formation of a modified region and a crack can be applied to various processes such as dicing to divide an object into a plurality of chips and trimming to remove unnecessary parts from the object.

[0008] An object of the present invention is to provide a laser processing device and a laser processing method which can form appropriate modified regions and cracks in an object according to processing.

[0009] Technical means of solving problems

[0010] A laser processing device according to one aspect of the present invention is, [1] "a laser processing device comprising: a support portion that supports an object; a light source that emits laser light; a spatial light modulator that modulates the laser light emitted from the light source by displaying a modulation pattern; a focusing portion that focuses the laser light modulated by the spatial light modulator on the object; a driving portion that drives at least one of the support portion and the focusing portion; and a control portion that controls at least the spatial light modulator and the driving portion, wherein the control portion controls the focusing point of the laser light. The beam shape of the laser beam is a beam shape including a central portion and a first extension portion, a second extension portion, and a third extension portion radially extending from the central portion and having the highest intensity in the central portion, so that a modulation pattern including a trefoil aberration pattern is displayed on a spatial light modulator, and the driving portion drives at least one of the supporting portion and the focusing portion so that the focusing point is relatively moved along a line set on the object while the modulation pattern including the trefoil aberration pattern is displayed on the spatial light modulator.

[0011] In the laser processing device described in [1] above, the beam shape of the laser light at the focal point includes a center portion and a first extension portion, a second extension portion, and a third extension portion radially extending from the center portion, and the focal point moves relatively along a line set on the object in a state where the center portion has the highest intensity. At this time, by adjusting the direction of the beam shape relative to the line, etc., it is possible to adjust the state of at least one of the modified region and the crack formed in the object. Therefore, according to the laser processing device described in [1] above, it is possible to form an appropriate modified region and crack in the object according to the processing.

[0012] The laser processing device according to one aspect of the present invention may also be, [2] "a laser processing device as described in [1] above, wherein, when a modified region is formed in the object along the line, and a crack is formed in the object along a first surface parallel to the incident direction of the laser and the extension direction of the line from the modified region, the control unit displays the modulation pattern including the trefoil aberration pattern on the spatial light modulator in a manner such that the first extension portion is located on the line and the second extension portion is located on one side relative to the line, and the third extension portion is located on the other side relative to the line". According to the laser processing device described in [2], the width of the crack in the incident direction of the laser can be reduced compared to, for example, a case where the modulation pattern does not include the trefoil aberration pattern.

[0013] The laser processing device according to one aspect of the present invention may also be, [3] "a laser processing device as described in [2] above, wherein the control unit displays the modulation pattern including the trefoil aberration pattern on the spatial light modulator in such a manner that the first extension portion is located at the front side of the direction in which the focal light spot moves relatively along the line, and the second extension portion and the third extension portion are located at the rear side of the direction". According to the laser processing device described in [3], not only the width of the crack in the incident direction of the laser light can be reduced, but also the width of the modified area in the incident direction of the laser light can be reduced. In addition, the meandering of the crack relative to the line can be reliably suppressed.

[0014] The laser processing device of one aspect of the present invention may also be, [4] "a laser processing device as described in [3] above, wherein, when the above-mentioned focal point is relatively moved along each of the first line and the second line set as the above-mentioned lines on the above-mentioned object, when the direction of the relative movement of the above-mentioned focal point along the above-mentioned first line is different from the direction of the relative movement of the above-mentioned focal point along the above-mentioned second line, the above-mentioned control unit switches the direction of the above-mentioned modulation pattern including the above-mentioned three-leaf aberration pattern in such a manner that the above-mentioned first extension unit is located in front of the directions in which the above-mentioned focal point moves relative to each of the above-mentioned first line and the above-mentioned second line, and the above-mentioned second extension unit and the above-mentioned third extension unit are located in the rear of the above-mentioned directions". According to the laser processing device described in [4], even when the direction in which the focusing light spot is relatively moved along the first line is different from the direction in which the focusing light spot is relatively moved along the second line, it is possible to easily and reliably achieve a state in which the first extension portion is located in front of the directions in which the focusing light spot is relatively moved along the first line and the second line and the second extension portion and the third extension portion are located in the rear of the directions.

[0015] The laser processing device according to one aspect of the present invention may also be, [5] "a laser processing device as described in any one of [2] to [4] above, wherein the control unit displays the modulation pattern of the trefoil aberration pattern including the first trefoil aberration intensity on the spatial light modulator when the width of at least one of the modified region and the crack in the incident direction of the laser is set to the first width, and displays the modulation pattern of the trefoil aberration pattern including the second trefoil aberration intensity stronger than the first trefoil aberration intensity on the spatial light modulator when the width of at least one of the modified region and the crack in the incident direction of the laser is set to the second width smaller than the first width". According to the laser processing device described in [5], the width of at least one of the modified region and the crack in the incident direction of the laser can be set to an appropriate width according to the processing.

[0016] The laser processing device according to one aspect of the present invention may also be, [6] "a laser processing device as described in [1] above, wherein, when a modified region is formed in the object along the line, and a crack is formed in the object along a second surface inclined relative to a first surface parallel to two directions of the incident direction of the laser and the extension direction of the line from the modified region, when the second surface is inclined in such a manner that a region on the opposite side of the incident side of the laser is located on one side in a direction perpendicular to the first surface, the control unit causes the modulation pattern including the three-leaf aberration pattern to be displayed on the spatial light modulator in such a manner that the first extension portion is located on one side relative to the line, and the second extension portion and the third extension portion are located on the other side relative to the line." According to the laser processing device described in [6], the crack extending from the modified region can be inclined toward a desired side.

[0017] The laser processing device of one aspect of the present invention may also be, [7] "a laser processing device as described in [6] above, wherein, when the above-mentioned focal point is relatively moved along each of the first line and the second line set as the above-mentioned lines on the above-mentioned object, when the direction of the relative movement of the above-mentioned focal point along the above-mentioned first line is different from the direction of the relative movement of the above-mentioned focal point along the above-mentioned second line, the above-mentioned control unit switches the direction of the above-mentioned modulation pattern including the above-mentioned three-leaf aberration pattern in such a manner that the above-mentioned first extension unit is located on the above-mentioned one side relative to each of the above-mentioned first line and the second line, and the above-mentioned second extension unit and the above-mentioned third extension unit are located on the other side relative to each of the above-mentioned first line and the second line." According to the laser processing device described in [7], even when the direction in which the focusing light spot is relatively moved along the first line is different from the direction in which the focusing light spot is relatively moved along the second line, it is possible to easily and reliably achieve a state in which the first extension portion is located on one side relative to each of the first line and the second line, and the second extension portion and the third extension portion are located on the other side relative to each of the first line and the second line.

[0018] The laser processing device of one aspect of the present invention may also be, [8] "a laser processing device as described in [6] or [7] above, wherein the control unit, when setting the angle between the first surface and the second surface to the first angle, causes the modulation pattern of the trefoil aberration pattern including the first trefoil aberration intensity to be displayed on the spatial light modulator, and when setting the angle to a second angle larger than the first angle, causes the modulation pattern of the trefoil aberration pattern including the second trefoil aberration intensity stronger than the first trefoil aberration intensity to be displayed on the spatial light modulator." According to the laser processing device described in [8], the angle of inclination of the crack extending from the modified area can be set to an appropriate angle according to the processing.

[0019] A laser processing method according to one aspect of the present invention is, [9] "a laser processing method is a laser processing method implemented in a laser processing device, the laser processing device comprising: a support portion that supports an object; a light source that emits laser light; a spatial light modulator that modulates the laser light emitted from the light source by displaying a modulation pattern; a focusing portion that focuses the laser light modulated by the spatial light modulator on the object; and a driving portion that drives at least one of the support portion and the focusing portion. The laser processing method comprises: The step of causing a modulation pattern including a trefoil aberration pattern to be displayed on a spatial light modulator in such a manner that a beam shape of the laser beam at the position becomes a beam shape including a central portion and a first extension portion, a second extension portion, and a third extension portion radially extending from the central portion and having the highest intensity at the central portion; and causing the driving portion to drive at least one of the supporting portion and the focusing portion in such a manner that the focusing point is relatively moved along a line set on the object while the modulation pattern including the trefoil aberration pattern is displayed on the spatial light modulator.

[0020] In the laser processing method described in [9] above, the beam shape of the laser light at the focal point includes a center portion and a first extension portion, a second extension portion, and a third extension portion radially extending from the center portion, and the focal point moves relatively along a line set on the object in a state where the center portion has the highest intensity. At this time, by adjusting the direction of the beam shape relative to the line, etc., it is possible to adjust the state of at least one of the modified region and the crack formed in the object. Therefore, according to the laser processing method described in [9] above, it is possible to form an appropriate modified region and crack in the object according to the processing.

[0021] Effects of the Invention

[0022] According to the present invention, it is possible to provide a laser processing apparatus and a laser processing method that can form appropriate modified regions and cracks in an object according to processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a diagram showing the structure of a laser processing device according to one embodiment.

[0024] Figure 2 Yes Display Figure 1 A diagram showing the structure of the irradiation unit.

[0025] Figure 3 Yes Display Figure 2 Diagram of the 4f lens unit shown.

[0026] Figure 4 Yes Display Figure 2 Diagram of the spatial light modulator shown.

[0027] Figure 5 This is a diagram showing an example of a trefoil aberration pattern.

[0028] Figure 6 This is a diagram showing an example of a laser light focusing state and an example of a laser light beam shape at a focusing point.

[0029] Figure 7 FIG. 1 is a diagram showing an example of a beam shape of laser light for each three-leaf aberration pattern intensity.

[0030] Figure 8 FIG. 1 is a diagram showing an example of a beam shape of laser light modulated by a three-leaf aberration pattern.

[0031] Fig. 9 This is a diagram showing an example of the beam shape of laser light modulated by a three-leaf aberration pattern and an astigmatism pattern.

[0032] Fig.10 This is a diagram showing an example of the beam shape of laser light modulated by a three-leaf aberration pattern, an astigmatism pattern, and a spherical aberration pattern.

[0033] Fig.11 FIG. 1 is a diagram showing an example of a beam shape of laser light modulated by a three-leaf aberration pattern.

[0034] Fig.12 This is a diagram showing an example of a laser light focusing state and an example of damage caused by laser light leakage.

[0035] Fig.13 This is a diagram showing a first example of a cut surface of an object for each laser processing condition.

[0036] Fig.14 This is a diagram showing a first example of a cut surface of an object for each laser processing condition.

[0037] Fig.15 It is a graph showing the relationship between the intensity of the trefoil aberration and the widths of the modified region and the cracks.

[0038] Fig.16 This is a diagram showing a second example of a cut surface of an object for each laser processing condition.

[0039] Fig.17 This is a diagram showing a second example of a cut surface of an object for each laser processing condition.

[0040] Fig.18 This is a graph showing the relationship between the intensity of the trefoil aberration and the angle of the crack inclination.

[0041] Fig.19This is a graph showing the relationship between the intensity of the trefoil aberration and the angle of the crack inclination.

[0042] Fig. 20 This is a diagram showing an object to which the first example of the laser processing method is applied.

[0043] Fig.21 This is a diagram showing one step of the first example of the laser processing method.

[0044] Fig. 22 The diagram shows an example of a cross section of an object processed by light leakage damage suppression.

[0045] Fig.23 This is a diagram showing an object to which the second example of the laser processing method is applied.

[0046] Fig.24 This is a diagram showing one step of the second example of the laser processing method. DETAILED DESCRIPTION

[0047] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In each of the drawings, the same or corresponding parts are denoted by the same reference numerals and overlapping descriptions may be omitted.

[0048] [Structure of laser processing device]

[0049] like Figure 1 As shown, the laser processing apparatus 1 includes a support unit 2, an irradiation unit 3, drive units 4 and 5, and a control unit 6. The laser processing apparatus 1 forms a modified region 12 in the object 11 by irradiating the object 11 with laser light L.

[0050] The support part 2 supports the object 11 by holding, for example, a film attached to the object 11. In the present embodiment, the support part 2 can move in each of the X direction and the Y direction, and can rotate about an axis parallel to the Z direction as a rotation axis. As an example, the X direction and the Y direction are the first horizontal direction and the second horizontal direction perpendicular to each other, and the Z direction is a vertical direction.

[0051] The irradiation unit 3 focuses the laser light L having transmittance to the object 11 and irradiates the object 11. In the present embodiment, the irradiation unit 3 is movable along the Z direction. If the laser light L is focused inside the object 11 supported by the support unit 2, the laser light L is particularly absorbed at a portion corresponding to the focused light spot C of the laser light L, and a modified region 12 is formed inside the object 11. The focused light spot C is also referred to as a focused region or a focused point.

[0052] The modified region 12 is a region whose density, refractive index, mechanical strength, and other physical properties are different from those of the surrounding non-modified region. The modified region 12 includes, for example, a melt-processed region, a crack region, an insulation breakdown region, and a refractive index change region. Cracks are formed from the modified region 12 toward the incident side of the laser L and the opposite side thereof. Such modified regions 12 and cracks are used to cut the object 11.

[0053] As an example, if the focused light spot C is relatively moved along a line A set on the object 11 and parallel to the X direction, a plurality of modified light spots 12s are formed along the line A in a manner arranged in a row. One modified light spot 12s is formed by irradiation with one pulse of laser light L. One row of modified regions 12 is a collection of a plurality of modified light spots 12s arranged in a row. Adjacent modified light spots 12s may be connected to each other or separated from each other depending on the relative moving speed of the focused light spot C with respect to the object 11 and the repetition frequency of the laser light L.

[0054] The driving unit 4 supports the supporting unit 2 and drives the supporting unit 2. In the present embodiment, the driving unit 4 moves the supporting unit 2 in each of the X direction and the Y direction, and rotates the supporting unit 2 with an axis parallel to the Z direction as a rotation axis. The driving unit 5 supports the irradiating unit 3 and drives the irradiating unit 3. In the present embodiment, the driving unit 5 moves the irradiating unit 3 in the Z direction. As an example, in the laser processing device 1, the driving unit 4 rotates the supporting unit 2 in such a manner that the line A becomes parallel to the X direction, moves the supporting unit 2 in the Y direction in such a manner that the focused light point C is located on the line A, moves the irradiating unit 3 in the Z direction in such a manner that the focused light point C is located inside the object 11, and further moves the supporting unit 2 in such a manner that the focused light point C is relatively moved along the line A.

[0055] The control unit 6 controls the support unit 2, the irradiation unit 3 and the driving 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, a memory, a storage, and a communication device. In the processing unit, the processor executes software (program) read into the memory, etc., controls the reading and writing of data in the memory and the storage, and the communication using the communication device. The storage unit is, for example, a hard disk, etc., which stores various data. The input receiving unit is an interface unit that displays various data and receives input of various information from the user. The input receiving unit constitutes, for example, a GUI (Graphical User Interface).

[0056] like Figure 2As shown, the irradiation section 3 includes a light source 31, a spatial light modulator 7, a focusing section 33, and a 4f lens unit 34. The light source 31 emits laser light L by, for example, a pulse oscillation method. The spatial light modulator 7 modulates the laser light L emitted from the light source 31 by displaying a modulation pattern. The focusing section 33 is composed of at least one lens, and focuses the laser light L modulated by the spatial light modulator 7 on the object 11. The 4f lens unit 34 transfers the image of the laser light L on the modulation surface of the spatial light modulator 7 to the entrance pupil surface of the focusing section 33. Furthermore, the light source 31 may be arranged outside the irradiation section 3, and the laser light L emitted from the light source 31 may be guided to the irradiation section 3. In addition, the irradiation section 3 may also include other optical systems. As an example, the irradiation section 3 may also include an optical system (such as an attenuator, a beam expander, etc.) arranged on the optical path between the light source 31 and the spatial light modulator 7.

[0057] like Figure 3 As shown, the 4f lens unit 34 has a pair of lenses 34A and 34B. The pair of lenses 34A and 34B are arranged on the optical path of the laser light L traveling from the spatial light modulator 7 to the focusing section 33. The pair of lenses 34A and 34B constitute a two-sided telecentric optical system in which the modulation surface 7a of the spatial light modulator 7 and the entrance pupil surface 33a of the focusing section 33 are in an imaging relationship. As a result, the image of the laser light L on the modulation surface 7a of the spatial light modulator 7 (the image of the laser light L modulated in the spatial light modulator 7) is transferred (imaged) to the entrance pupil surface 33a of the focusing section 33. Furthermore, in Figure 3 In FIG. 1 , f1 and f2 respectively indicate the focal lengths of lenses 34A and 34B, and Fs indicates the Fourier surface.

[0058] like Figure 4 As shown, the spatial light modulator 7 is a spatial light modulator (SLM) of reflective liquid crystal (LCOS: Liquid Crystal on Silicon). The spatial light modulator 7 is composed of a driving circuit layer 72, a pixel electrode layer 73, a reflection film 74, an orientation film 75, a liquid crystal layer 76, an orientation film 77, a transparent conductive film 78 and a transparent substrate 79 stacked on a semiconductor substrate 71 in this order.

[0059] The semiconductor substrate 71 is, for example, a silicon substrate. The driving circuit layer 72 forms 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 metal material such as aluminum. A voltage is applied to each pixel electrode 73a through the driving circuit layer 72.

[0060] The reflective film 74 is, for example, a dielectric multilayer film. The orientation film 75 is provided on the surface of the liquid crystal layer 76 on the reflective film 74 side, and the orientation film 77 is provided on the surface of the liquid crystal layer 76 on the opposite side to the reflective film 74. Each of the orientation films 75 and 77 is formed of a polymer material such as polyimide, and a rubbing treatment is applied to the contact surface of each of the orientation films 75 and 77 with the liquid crystal layer 76. The orientation films 75 and 77 align the liquid crystal molecules 76a contained in the liquid crystal layer 76 in a certain direction.

[0061] The transparent conductive film 78 is provided on the surface of the transparent substrate 79 on the side of the orientation film 77, and is opposite to the pixel electrode layer 73 via the liquid crystal layer 76 and the like. The transparent substrate 79 is, for example, a glass substrate. The transparent conductive film 78 is formed of a light-transmitting and conductive material such as ITO. The transparent substrate 79 and the transparent conductive film 78 allow the laser light L to pass through.

[0062] In the spatial light modulator 7 configured as described above, if a signal for displaying 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 the electric field is formed, the arrangement direction of the liquid crystal molecules 76a in each region corresponding to each pixel electrode 73a in the liquid crystal layer 76 changes, and the refractive index changes in each region corresponding to each pixel electrode 73a. This state is a state in which the spatial light modulator 7 displays a modulation pattern.

[0063] When the spatial light modulator 7 displays the modulation pattern, if the laser light L enters the liquid crystal layer 76 from the outside through the transparent substrate 79 and the transparent conductive film 78, is reflected by the reflective film 74, and is emitted from the liquid crystal layer 76 through the transparent conductive film 78 and the transparent substrate 79 to the outside, the intensity, amplitude, phase, polarization, etc. of the laser light L are modulated according to the modulation pattern displayed on the liquid crystal layer 76. Figure 3 The modulation surface 7 a shown corresponds to the liquid crystal layer 76 .

[0064] [Laser processing method using three-leaf aberration pattern]

[0065] In the laser processing apparatus 1 , the control unit 6 can cause the spatial light modulator 7 to display a modulation pattern including a trefoil aberration pattern. Figure 5 : is a diagram showing an example of a trefoil aberration pattern. Trefoil aberration is one of Zernike's third-order aberrations. Spherical aberration and astigmatism are included in Zernike's second-order aberrations, and coma and trefoil aberration are included in Zernike's third-order aberrations.

[0066] If the laser light L modulated by the spatial light modulator 7 showing the trefoil aberration pattern is focused by the focusing section 33, Figure 6As shown in (a), the laser light L is most concentrated at the focusing point C. At this time, the beam shape 9 of the laser light L at the focusing point C (i.e., “with respect to the optical axis ( Figure 6 The intensity distribution of the laser light L in the plane "a" which is perpendicular to the dashed line (shown in (a) and includes the focused light point C) is as follows Figure 6 As shown in (b), the beam shape includes a center portion 90 and a first extension portion 91, a second extension portion 92, and a third extension portion 93 radially extending from the center portion 90, and has the highest intensity at the center portion 90. As an example, the widths of the first extension portion 91, the second extension portion 92, and the third extension portion 93 decrease as they are farther away from the center portion 90, and the intensities of the first extension portion 91, the second extension portion 92, and the third extension portion 93 decrease as they are farther away from the center portion 90. As an example, the beam shape 9 of the laser light L is a shape in which the sides of a triangle are bent inward.

[0067] Furthermore, the modulation pattern including the trefoil aberration pattern includes, of course, a modulation pattern including only the trefoil aberration pattern and a modulation pattern including the trefoil aberration pattern and other patterns. Even in the case where the modulation pattern includes other patterns than the trefoil aberration pattern, if the laser light L modulated by the spatial light modulator 7 displaying the modulation pattern including the trefoil aberration pattern is focused by the focusing portion 33, the beam shape 9 of the laser light L at the focused light spot C becomes a beam shape including the center portion 90 and the first extended portion 91, the second extended portion 92, and the third extended portion 93 extending radially from the center portion 90, and having the highest intensity at the center portion 90. As an example, if the laser light L modulated by the spatial light modulator 7 displaying a modulation pattern including a three-leaf aberration pattern and an astigmatism pattern is focused through the focusing portion 33, a plurality of focusing spots C appear. However, even in this case, the beam shape 9 of the laser light L at each focusing spot C (in this case, the intensity distribution of the laser light L within the “plane which is perpendicular to the optical axis of the laser light L focused on the focusing spot C and includes the focusing spot C”) becomes a beam shape including a central portion 90 and a first extension portion 91, a second extension portion 92, and a third extension portion 93 which extend radially from the central portion 90 and have the highest intensity at the central portion 90.

[0068] Figure 7 This is a diagram showing an example of the beam shape of laser light L for each trefoil aberration pattern intensity. The absolute value of the trefoil aberration intensity shows the intensity of the trefoil aberration. The larger the absolute value of the trefoil aberration intensity becomes, the stronger the trefoil aberration becomes (therefore, "strong trefoil aberration intensity" means that the absolute value of the trefoil aberration intensity is large). The positive and negative signs of the trefoil aberration intensity show the direction of the trefoil aberration. The direction of the trefoil aberration differs by 180 degrees between the trefoil aberration with a positive sign and the trefoil aberration with a negative sign. Figure 7In FIG. 1 , a camera image captured by a camera is displayed as the beam shape of the laser L.

[0069] like Figure 7 As shown, even when the laser light L is modulated by a three-leaf aberration pattern having an arbitrary three-leaf aberration intensity, the beam shape 9 of the laser light L at the focused light spot C is a beam shape including a central portion 90 and a first extended portion 91, a second extended portion 92, and a third extended portion 93, and having the highest intensity at the central portion 90 (see Figure 6 (b)). At this time, the beam shape of the laser L at the position of -20μm and the beam shape of the laser L at the position of +20μm also become beam shapes having the same shape and direction as the beam shape 9 of the laser L at the focusing point C. It can be seen that the beam shape 9 of the laser L at the focusing point C sometimes appears to be oriented to the opposite sides of the beam shape of the laser L at the position of -20μm and the beam shape of the laser L at the position of +20μm when the camera image is first glanced at, but even in this case, if not only the high-intensity part but also the low-intensity part is included, it is oriented to the same side as these beam shapes. Furthermore, the "-20μm position" is a position separated by 20μm from the focusing point C toward the focusing portion 33 side, and the "+20μm position" is a position separated by 20μm from the focusing point C toward the opposite side of the focusing portion 33.

[0070] Figure 8 : is a diagram showing an example of the beam shape of the laser light L modulated by the three-leaf aberration pattern. Fig. 9 1 is a diagram showing an example of the beam shape of the laser light L modulated by the three-leaf aberration pattern and the astigmatism pattern (that is, the modulation pattern obtained by superimposing them). Fig.10 : is a diagram showing an example of the beam shape of laser light L modulated by a three-leaf aberration pattern, an astigmatism pattern, and a spherical aberration (that is, a modulation pattern after these are superimposed). Figure 8 , Fig. 9 and Fig.10 In FIG. 1 , as the beam shape of the laser light L, a simulated image obtained by simulation and a camera image captured by a camera are displayed. Figure 8 , Fig. 9 and Fig.10 In any case, the trefoil aberration intensity of the trefoil aberration pattern is -0.6.

[0071] like Figure 8 , Fig. 9 and Fig.10 As shown in FIG. 1 , if the laser light L is modulated by a modulation pattern including a three-leaf aberration pattern, the beam shape 9 of the laser light L at the focused light spot C becomes a beam shape including a central portion 90 and a first extension portion 91, a second extension portion 92, and a third extension portion 93, and having the highest intensity at the central portion 90 (see FIG. 1 ). Figure 6 (b)). At this time, the beam shape of the laser L at the position of -20 μm and the beam shape of the laser L at the position of +20 μm also become beam shapes having the same shape and direction as the beam shape 9 of the laser L at the focusing point C. It can be seen that the beam shape 9 of the laser L at the focusing point C sometimes appears to be oriented to the opposite sides when the camera image is first viewed, but even in this case, if not only the high-intensity portion but also the low-intensity portion is included, it is oriented to the same side as these beam shapes.

[0072] Fig.11 : is a diagram showing an example of the beam shape of the laser light L modulated by the trefoil aberration pattern. In this case, the trefoil aberration intensity of the trefoil aberration pattern is -0.5. Fig.11 As shown, the beam shape of the laser light L at the position of -100 μm and the beam shape of the laser light L at the position of +100 μm are beam shapes that are oriented to the opposite side of the beam shape 9 of the laser light L at the focusing point C. Furthermore, the "position of -100 μm" is a position separated by 100 μm from the focusing point C toward the focusing portion 33 side, and the "position of +100 μm" is a position separated by 100 μm from the focusing point C toward the opposite side of the focusing portion 33.

[0073] On the other hand, as described above, the beam shape of the laser light L at the position of -20 μm and the beam shape of the laser light L at the position of +20 μm become beam shapes having the same shape and direction as the beam shape 9 of the laser light L at the focusing point C (see Figure 7 , Figure 8 , Fig. 9 and Fig.10 ). In particular, the beam shape of the laser light L at the position of -20 μm significantly shows the beam shape 9 of the laser light L at the focusing point C compared to the beam shape of the laser light L at the position of +20 μm. Therefore, in the case where the laser light L modulated by the modulation pattern including the trefoil aberration pattern is focused, in order to estimate the beam shape 9 of the laser light L at the focusing point C, the beam shape of the laser light L at the position of -20 μm is photographed by a camera and the camera image is observed.

[0074] In addition, if Fig.12As shown in (a) of FIG. 1 , if a metal film 8 is formed on the second surface 11b of an object 11, which is a silicon wafer, and the first surface 11a of the object 11 is used as the incident surface of the laser light L and the focusing light spot C is aligned at a position 20 to 30 μm from the second surface 11b, that is, at a position inside the object 11, and the laser light L is irradiated to the object 11, then when the laser light L modulated by the modulation pattern including the three-leaf aberration pattern is focused, as shown in FIG. Fig.12 As shown in (b), damage having the same shape and orientation as the beam shape 9 of the laser light L at the focusing point C is formed on the metal film 8. Therefore, in the case where the laser light L modulated by the modulation pattern including the trefoil aberration pattern is focused, in order to estimate the beam shape 9 of the laser light L at the focusing point C, damage is formed on the metal film 8 as described above and the damage is observed.

[0075] Based on the above description, a first example of a modified region and cracks (cracks extending from the modified region when the modified region is formed) formed by a laser processing method using a three-leaf aberration pattern will be described. Fig.13 and Fig.14 1 is a diagram showing a first example of a cross section of an object 11 for each laser processing condition. Fig.13 and Fig.14 The cross section of the object 11 is shown in which "inside the object 11 which is a silicon wafer, two rows of modified regions arranged in the thickness direction of the silicon wafer are formed along the line A, and then the object 11 is cut along the line A by expansion."

[0076] exist Fig.13 and Fig.14 In the condition A, the direction indicated by the arrow on line A is Fig.13 Middle is to the right, Fig.14 The focusing point C is relatively moved (leftward in the figure), and the beam shape 9 of the laser light L at the focusing point C becomes (1) "the central part 90 and the first extension part 91 are located on the line A and the second extension part 92 is located on the first side (on the left side) relative to the line A. Fig.13 The middle is the upper side, Fig.14 The third extension portion 93 is located on the second side (at the bottom) relative to line A. Fig.13 For the lower side, Fig.14 The laser processing conditions are as follows: (1) a state in which the first extension portion 91 is located on the front side of a direction in which the focusing light spot C moves relatively along line A, and (2) a state in which the second extension portion 92 and the third extension portion 93 are located on the rear side of the direction.

[0077] In addition, "condition B" is to follow the "direction indicated by the arrow on line A" (in Fig.13 Middle is to the left, Fig.14The focusing point C is relatively moved (rightward in the figure). At this time, the beam shape 9 of the laser light L at the focusing point C becomes (1) "the central part 90 and the first extension part 91 are located on the line A and the second extension part 92 is located on the second side (at the right side) relative to the line A. Fig.13 The middle is the upper side, Fig.14 The third extension portion 93 is located on the first side (at the bottom) relative to the line A. Fig.13 The middle is the lower side, Fig.14 The laser processing conditions are as follows: (1) a state in which the first extension portion 91 is located on the rear side of the direction in which the focusing light spot C is relatively moved along line A, and (2) a state in which the second extension portion 92 and the third extension portion 93 are located on the front side of the direction.

[0078] Furthermore, the "standard" in the paragraph "Condition A" is a laser processing condition that differs from "Condition A" only in that the modulation pattern does not include a trefoil aberration pattern. In addition, the "standard" in the paragraph "Condition B" is a laser processing condition that differs from "Condition B" only in that the modulation pattern does not include a trefoil aberration pattern.

[0079] For Fig.13 and Fig.14 The state of the cross section of the object 11 shown in FIG. Fig.15 Provide explanation.

[0080] First, if Fig.15 As shown in FIG. 1 , in a case where a modified region 12 is formed in an object 11 along a line A, and a crack 13 is formed in the object 11 along a first plane P1 parallel to two directions, namely, the incident direction of the laser light L (Z direction) and the extension direction of the line A (X direction), from the modified region 12, when the width of the crack 13 in the incident direction of the laser light L is reduced, the first extension portion 91 is located on the line A, the second extension portion 92 is located on one side relative to the line A, and the third extension portion 93 is located on the other side relative to the line A (in Fig.13 and Fig.14 , “Condition A” and “Condition B”), the modulation pattern including the three-leaf aberration pattern can be displayed on the spatial light modulator 7.

[0081] Furthermore, in Fig.13 and Fig.14 On the cut surface of the object 11 shown, the width of the crack in the incident direction of the laser light L becomes smaller, and it can be seen from the fact that a black stripe extending in the left-right direction is formed between two rows of modified regions (black band-shaped regions extending in the left-right direction). This is because when the object 11 is cut by extension when two rows of modified regions are formed, the cracks extending from each modified region are not connected between the modified regions, and black stripes extending in the left-right direction can be formed.

[0082] In addition, if Fig.15 As shown in FIG. 1 , when the modified region 12 is formed in the object 11 along the line A and the crack 13 is formed in the object 11 along the first plane P1, when not only the width of the crack 13 in the incident direction of the laser light L is reduced, but also the width of the modified region 12 in the incident direction of the laser light L is reduced, and the crack 13 is suppressed from meandering relative to the line A, the first extension portion 91 is located on the front side of the direction in which the focused light spot C is relatively moved along the line A, and the second extension portion 92 and the third extension portion 93 are located on the rear side of the direction (in the Fig.13 and Fig.14 In the above example, the modulation pattern including the trefoil aberration pattern is displayed on the spatial light modulator 7. Fig.13 and Fig.14 On the cut surface of the object 11 shown, the meandering of the crack 13 relative to the line A is suppressed, and it can be seen from the black stripes (called twist comb lines) extending in the upward and downward directions from the two rows of modified areas that are less under "Condition A" than under "Standard" and "Condition B".

[0083] Furthermore, in the case where the focal point C is relatively moved along each of the first line and the second line set as the line A on the object 11, when the direction in which the focal point C is relatively moved along the first line is different from the direction in which the focal point C is relatively moved along the second line, the direction of the modulation pattern including the trefoil aberration pattern can be switched in the spatial light modulator 7 in such a manner that the first extension portion 91 is located in front of the directions in which the focal point C is relatively moved along the first line and the second line and the second extension portion 92 and the third extension portion 93 are located in the rear of the directions.

[0084] In addition, if Fig.15 As shown, when the width of at least one of the modified region 12 and the crack 13 in the incident direction (Z direction) of the laser L is set to a first width, a modulation pattern of a trefoil aberration pattern including a first trefoil aberration intensity is displayed on the spatial light modulator 7, and when the width of at least one of the modified region 12 and the crack 13 is set to a second width smaller than the first width, a modulation pattern of a trefoil aberration pattern including a second trefoil aberration intensity stronger than the first trefoil aberration intensity is displayed on the spatial light modulator 7. Fig.15 In the example shown, the widths of the modified region 12 and the cracks 13 in the incident direction of the laser light L become smaller in the second trefoil aberration intensity than in the first trefoil aberration intensity.

[0085] Next, a second example of a modified region and cracks (cracks extending from the modified region when the modified region is formed) formed by the laser processing method using a three-leaf aberration pattern will be described. Fig.16 and Fig.171 is a diagram showing a second example of a cross section of the object 11 for each laser processing condition. Fig.16 and Fig.17 , a cross-section of the object 11 is shown in which "inside the object 11 which is a silicon wafer, two rows of modified regions arranged in the thickness direction of the silicon wafer are formed along the line A, and then the object 11 is cut along the line A by expansion."

[0086] exist Fig.16 and Fig.17 In the condition C, the direction indicated by the arrow on line A is Fig.16 Middle is right, Fig.17 The focusing point C is relatively moved (leftward in the figure), and at this time, the beam shape 9 of the laser light L at the focusing point C becomes (4) "the central part 90 is located on the line A and the first extension part 91 is located on the first side (at the left side) relative to the line A. Fig.16 The middle is the upper side, Fig.17 The second extension portion 92 and the third extension portion 93 are located on the second side (at the bottom) relative to the line A. Fig.16 The middle is the lower side, Fig.17 The laser processing conditions are as follows:

[0087] In addition, "condition D" is to follow the "direction indicated by the arrow on line A" (in Fig.16 To the left, Fig.17 The focusing point C is relatively moved to the right. At this time, the beam shape 9 of the laser light L at the focusing point C becomes (5) "the center portion 90 is located on the line A and the first extension portion 91 is located on the second side (at the right side) relative to the line A. Fig.16 For the upper side, Fig.17 The second extension portion 92 and the third extension portion 93 are located on the first side (at the bottom) relative to the line A. Fig.16 For the lower side, Fig.17 The laser processing conditions are as follows:

[0088] Furthermore, the "standard" in the paragraph "Condition C" is a laser processing condition that differs from "Condition C" only in that the modulation pattern does not include a trefoil aberration pattern. In addition, the "standard" in the paragraph "Condition D" is a laser processing condition that differs from "Condition D" only in that the modulation pattern does not include a trefoil aberration pattern.

[0089] For Fig.16 and Fig.17 The state of the cross section of the object 11 shown in FIG. Fig.18 and Fig.19 Provide explanation.

[0090] First, if Fig.18As shown in FIG. 1 , when a modified region 12 is formed in the object 11 along the line A, and a crack 13 is formed in the object 11 along the second surface P2 inclined with respect to the first surface P1 parallel to both the incident direction of the laser light L (Z direction) and the extending direction of the line A (X direction) from the modified region 12, the region on the opposite side to the incident side of the laser light L is located on one side (in the direction perpendicular to the first surface P1) in the direction (Y direction) perpendicular to the first surface P1. Fig.18 When the second surface P2 is inclined in such a manner that the first extension portion 91 is located on one side (on the left side) relative to the line A, Fig.18 is the left side), and relative to line A, the second extension portion 92 and the third extension portion 93 are located on the other side (at Fig.18 By using the method (as shown on the right side), the modulation pattern including the three-leaf aberration pattern can be displayed on the spatial light modulator 7.

[0091] In addition, if Fig.19 As shown in FIG. 1 , when a modified region 12 is formed in the object 11 along the line A, and a crack 13 is formed in the object 11 along the second surface P2 inclined with respect to the first surface P1 parallel to both the incident direction of the laser light L (Z direction) and the extending direction of the line A (X direction) from the modified region 12, the region on the opposite side to the incident side of the laser light L is located on one side (in the direction perpendicular to the first surface P1) in the direction (Y direction) perpendicular to the first surface P1. Fig.19 When the second surface P2 is inclined in such a manner that the first extension portion 91 is located on the other side (on the right side) relative to the line A, Fig.19 is the right side) and relative to line A, the second extension portion 92 and the third extension portion 93 are located on one side (at Fig.19 By using the method (as shown on the left side), the modulation pattern including the three-leaf aberration pattern can be displayed on the spatial light modulator 7.

[0092] Furthermore, in the case where the focal point C is relatively moved along each of the first line and the second line set as the line A on the object 11, when the direction in which the focal point C is relatively moved along the first line is different from the direction in which the focal point C is relatively moved along the second line, the direction of the modulation pattern including the trefoil aberration pattern is switched in the spatial light modulator 7 in such a manner that the first extension portion 91 is located on one side relative to each of the first line and the second line, and the second extension portion 92 and the third extension portion 93 are located on the other side relative to each of the first line and the second line.

[0093] In addition, if Fig.18 and Fig.19As shown, when the angle between the first surface P1 and the second surface P2 (i.e., the angle on the acute angle side formed by the first surface P1 and the second surface P2) is set to a first angle, a modulation pattern of a trefoil aberration pattern including a first trefoil aberration intensity is displayed on the spatial light modulator 7, and when the angle is set to a second angle larger than the first angle, a modulation pattern of a trefoil aberration pattern including a second trefoil aberration intensity stronger than the first trefoil aberration intensity is displayed on the spatial light modulator 7. Fig.16 and Fig.17 In the cross section of the object 11 shown, the stronger the trefoil aberration intensity becomes, the larger the angle of the crack inclination becomes. This is apparent from the fact that the stronger the trefoil aberration intensity becomes, the larger the black area becomes. Fig.16 and Fig.17 The cross section of the object 11 shown is inclined so that the side where the black area increases is located on the front side of the paper.

[0094] [First example of laser processing method]

[0095] Fig. 20 1 is a diagram showing an object 11 of a first example to which a laser processing method is applied. Fig. 20 As shown, the object 11 is a semiconductor wafer having a first surface 11a and a second surface 11b. As an example, the object 11 includes a silicon wafer and a plurality of functional elements (not shown) formed on the first surface 11a side of the silicon wafer. The plurality of functional elements are arranged in a matrix along the first surface 11a with a notch 11c formed in the object 11 as a reference. Each functional element is, for example, a light-receiving element such as a light-emitting diode, a light-emitting element such as a laser diode, a circuit element such as a memory, etc. Each functional element may be stacked in a three-dimensional manner with a plurality of layers. Furthermore, an orientation plane may be formed in the object 11 instead of the notch 11c.

[0096] The first example of the laser processing method is implemented in the above-mentioned laser processing device 1. In the first example of the laser processing method, Fig. 20 The object 11 shown is cut along a plurality of processing surfaces P10 extending in a grid pattern for each functional element. Each processing surface P10 is a plane perpendicular to the first surface 11a and the second surface 11b. In the first example of the laser processing method, Fig.21 As shown in (a) and (b), when the processing surface P10 is aligned with the first surface P1 which is parallel to two directions, namely the incident direction (Z direction) of the laser L and the extension direction (X direction) of the line A, two rows of modified regions 12 arranged in the thickness direction of the object 11 are formed along the line A inside the object 11.

[0097] In the first example of the laser processing method, a modified region 12 is to be formed in the object 11 along a line A extending in the processing surface P10, and a crack 13 is to be formed in the object 11 along the first surface P1. In addition, in the first example of the laser processing method, since the object 11 is thin, the widths of the modified region 12 and the crack 13 in the incident direction of the laser L are to be reduced and the crack 13 is to be suppressed from meandering relative to the line A.

[0098] Therefore, in the first example of the laser processing method, the control unit 6 causes the spatial light modulator 7 to display a modulation pattern including a trefoil aberration pattern in such a manner that the first extension portion 91 is located on the line A and the second extension portion 92 is located on one side relative to the line A and the third extension portion 93 is located on the other side relative to the line A, and the first extension portion 91 is located on the front side of the direction in which the light-converging spot C is relatively moved along the line A and the second extension portion 92 and the third extension portion 93 are located on the rear side of the direction. At this time, in the case of further reducing the widths of the modified region 12 and the crack 13 in the incident direction of the laser light L, the control unit 6 causes the spatial light modulator 7 to display a modulation pattern including a trefoil aberration pattern with a stronger trefoil aberration intensity. Next, in the state in which the modulation pattern including the trefoil aberration pattern is displayed on the spatial light modulator 7, the control unit 6 causes the drive unit 4 to drive the support unit 2 in such a manner that the light-converging spot C is relatively moved along the line A. After the above steps are performed on all the processed surfaces P10, the dicing tape affixed to the second surface 11b of the object 11 is expanded. Fig. 20 The object 11 shown is cut into sections for each functional element.

[0099] Furthermore, in the first example of the laser processing method, the laser light L may be incident from the first surface 11a side of the object 11, or the laser light L may be incident from the second surface 11b side of the object 11. In addition, a row of modified regions 12 may be formed inside the object 11 along the line A, or three or more rows of modified regions 12 arranged in the thickness direction of the object 11 may be formed inside the object 11 along the line A. In the case where a plurality of rows of modified regions 12 arranged in the thickness direction of the object 11 are formed inside the object 11 along the line A, the laser light L may be modulated by the spatial light modulator 7 in a manner having a plurality of focused light spots C, and a plurality of rows of modified regions 12 may be formed inside the object 11 along the line A by scanning the laser light L once (relative movement of the laser light L along the line A). In addition, during laser processing, a dicing tape may be attached to the first surface 11a or the second surface 11b on the opposite side of the surface on which the laser L is incident, or a dicing tape having transparency to the laser L may be attached to the first surface 11a or the second surface 11b on which the laser L is incident. In addition, after the laser processing and before the dicing tape is expanded, the second surface 11b of the object 11 may be polished to thin the object 11. At this time, the modified region 12 formed on the object 11 may be removed.

[0100] In the first example of the laser processing method, when forming a surface close to the emission side of the laser L (at Fig.21 In the example shown, the modified region 12 (hereinafter referred to as the "first modified region") of the second surface 11b is formed so that the cracks 13 do not reach the surface on the emission side of the laser L from the first modified region. Fig.21In the example shown, when a modified region 12 (hereinafter referred to as "second modified region") is formed between the first surface 11a and the second modified region, a crack 13 is connected between the first modified region and the second modified region, and the crack 13 is made to reach the surface on the emission side of the laser light L from the first modified region (hereinafter referred to as "light leakage damage suppression processing"). In this case, it is preferred that when the first modified region is formed, the control unit 6 displays a modulation pattern including a trefoil aberration pattern on the spatial light modulator 7 in such a manner that the first extension portion 91 is located on the line A and the second extension portion 92 is located on one side relative to the line A, and the third extension portion 93 is located on the other side relative to the line A, and when the second modified region is formed, the control unit 6 displays a modulation pattern not including a trefoil aberration pattern (or a modulation pattern including a trefoil aberration pattern with a weaker trefoil aberration intensity than when the first modified region is formed) on the spatial light modulator 7. According to such a laser processing method, since the scattering of the leakage light of the laser light L is suppressed when forming the first modified region, it is possible to suppress the damage caused by the leakage light on the surface on the emission side of the laser light L. In addition, the quality of the end face can be improved (that is, the unevenness of the cut surface can be reduced), and such an effect can be further improved by suppressing the twist comb pattern using a modulation pattern including a three-leaf aberration pattern.

[0101] Furthermore, when the first modified region is formed, if the control unit 6 displays a modulation pattern including a trefoil aberration pattern on the spatial light modulator 7 in a manner such that the first extension portion 91 is located on the line A and the second extension portion 92 is located on one side relative to the line A and the third extension portion 93 is located on the other side relative to the line A, and the first extension portion 91 is located on the front side of a direction in which the focal light spot C moves relatively along the line A and the second extension portion 92 and the third extension portion 93 are located on the rear side of the direction, then the crack 13 can be more reliably prevented from reaching the surface on the exit side of the laser light L from the first modified region.

[0102] The above-mentioned viewpoint is applicable to the case where "at least one row of first modified regions" and "at least one row of second modified regions" arranged in the thickness direction of the object 11 are formed inside the object 11 along the line A. In this case, the number of rows of the first modified regions and the number of rows of the second modified regions may be the same as or different from each other.

[0103] When a plurality of rows of first modified regions arranged in the thickness direction of the object 11 are formed inside the object 11 along the line A, in order to shorten the time required for laser processing (i.e., for so-called speed-up), the laser light L may be modulated by the spatial light modulator 7 so as to have a plurality of focused light spots C, and a plurality of rows of first modified regions may be formed inside the object 11 along the line A by a single scan of the laser light L. In this case, the control unit 6 may cause the spatial light modulator 7 to display a modulation pattern including a trefoil aberration pattern so that the first extension portion 91 is located on the line A, the second extension portion 92 is located on one side relative to the line A, and the third extension portion 93 is located on the other side relative to the line A. Alternatively, the control unit 6 may display a modulation pattern including a trefoil aberration pattern on the spatial light modulator 7 in such a manner that the first extension portion 91 is located on the line A, the second extension portion 92 is located on one side relative to the line A, and the third extension portion 93 is located on the other side relative to the line A, and the first extension portion 91 is located on the front side of the direction in which the focused light spot C is relatively moved along the line A, and the second extension portion 92 and the third extension portion 93 are located on the rear side of the direction. Of course, a plurality of columns of first modified regions may be formed along the line A in each of a plurality of scans of the laser light L. Furthermore, in the case where a plurality of columns of first modified regions are formed along the line A in the object 11 by a single scan of the laser light L, and in the case where a plurality of columns of first modified regions are formed along the line A in the object 11 by each of a plurality of scans of the laser light L, it is preferable that the cracks extending from the plurality of columns of first modified regions are not connected to each other.

[0104] In addition, when a plurality of rows of second modified regions arranged in the thickness direction of the object 11 are formed along the line A inside the object 11, in order to increase the speed, the laser L may be modulated by the spatial light modulator 7 in a manner having a plurality of focused light spots C, and a plurality of rows of second modified regions may be formed along the line A inside the object 11 by a single scan of the laser L. Of course, when a plurality of rows of second modified regions arranged in the thickness direction of the object 11 are formed along the line A inside the object 11, a plurality of rows of second modified regions may be formed along the line A inside the object 11 by each of a plurality of scans of the laser L. Furthermore, when a plurality of rows of second modified regions are formed along the line A inside the object 11 by a single scan of the laser L, or when a plurality of rows of second modified regions are formed along the line A inside the object 11 by each of a plurality of scans of the laser L, it is preferable that the cracks extending from the plurality of rows of second modified regions are connected to each other.

[0105] Fig. 22 The diagram shows an example of a cross section of the object 11 processed by light leakage damage suppression. Fig. 22The examples of the cross sections shown in (a) and (b) are obtained by forming "three rows of first modified regions" and "three rows of second modified regions" arranged in the thickness direction of the object 11 along the line A inside the object 11. Fig. 22 In either (a) or (b), three rows of first modified regions are formed along line A inside the object 11 by scanning the laser L once, and then three rows of second modified regions are formed along line A inside the object 11 by scanning the laser L once. Fig. 22 In (a), when three rows of first modified regions are formed, a modulation pattern that does not include a trefoil aberration pattern is displayed on the spatial light modulator 7. Fig. 22 In (b), when three rows of first modified regions are formed, the first extension portion 91 may be located on line A, the second extension portion 92 may be located on one side relative to line A, and the third extension portion 93 may be located on the other side relative to line A, and the first extension portion 91 may be located on the front side of the direction in which the focused light point C moves relatively along line A, and the second extension portion 92 and the third extension portion 93 may be located on the rear side of the direction, so that a modulation pattern including a trefoil aberration pattern is displayed on the spatial light modulator 7. As a result, in Fig. 22 In (a), in the region where three rows of the first modified region are formed, twist lines are generated and the extension mode of the cracks is also unstable. Fig. 22 In (b), in the region where three rows of first modified regions are formed, the generation of twist lines is suppressed and the extension mode of cracks is also stable.

[0106] [Second example of laser processing method]

[0107] Fig.23 (a) and (b) are diagrams showing an object 100 of a second example to which the laser processing method is applied. Fig.23 As shown in (a) and (b) of the present invention, the object 100 includes an object 11 and an object 11R which is a component different from the object 11. Each of the objects 11 and 11R is, for example, a silicon wafer. A device layer 110 including a plurality of functional elements (not shown) is formed on the second surface 11b of the object 11. A device layer 110R including a plurality of functional elements (not shown) is formed on one surface of the object 11R. The device layer 110 and the device layer 110R are bonded to each other.

[0108] The second example of the laser processing method is implemented in the above-mentioned laser processing device 1. In the second example of the laser processing method, Fig.23The object 11 shown in (a) and (b) is cut along a processing surface P11, a processing surface P12, and a plurality of processing surfaces P13, respectively, and the outer edge portion of the object 11 is removed (finishing processing). The processing surface P11 is a cylindrical surface having a center line parallel to the Z direction. The processing surface P12 is a truncated cone-shaped tapered surface extending from the end of the processing surface P11 on the device layer 110 side toward the outer edge of the device layer 110R. The plurality of processing surfaces P13 are planes extending from the processing surface P11 toward the outer edge of the object 11. In the second example of the laser processing method, as Fig.24 As shown in (a) and (b) of FIG. 1 , in a state where the processed surface P12 is aligned with the second surface P2 inclined relative to the first surface P1 parallel to both the incident direction of the laser light L (Z direction) and the extending direction of the line A (X direction), in the portion along the processed surface P12 inside the object 11, two rows of modified regions 12 arranged in the thickness direction of the object 11 are formed along the line A. Furthermore, in the second example of the laser processing method, the line A extends in a circular shape within the processed surface P12, but the extending direction of the line A when the line A is a curve refers to the tangent direction of the curve.

[0109] In the second example of the laser processing method, a modified region 12 is formed in the object 11 along a line A extending in the processing surface P12, and a crack 13 is formed in the object 11 along the second surface P2. In addition, in the second example of the laser processing method, the second surface P2 is inclined so that the area on the opposite side of the incident side of the laser light L is located on the outside in the direction (Y direction) perpendicular to the first surface P1.

[0110] Therefore, in the second example of the laser processing method, the control unit 6 causes the spatial light modulator 7 to display a modulation pattern including a trefoil aberration pattern so that the first extension portion 91 is located outside the line A and the second extension portion 92 and the third extension portion 93 are located inside the line A. At this time, in the case where the angle between the first plane P1 and the second plane P2 is to be further increased, the control unit 6 causes the spatial light modulator 7 to display a modulation pattern including a trefoil aberration pattern with a stronger trefoil aberration intensity. Next, in the state where the modulation pattern including the trefoil aberration pattern is displayed on the spatial light modulator 7, the control unit 6 causes the driving unit 4 to drive the supporting unit 2 so that the focused light spot C is relatively moved along the line A. Next, a plurality of modified regions 12 arranged in the thickness direction of the object 11 are formed along the processing plane P11 and the plurality of processing planes P13. After the above steps are performed, the outer edge portion of the object 11 is removed, and further, by grinding the first surface 11 a of the object 11 , the portion where the processed surface P11 is set is removed.

[0111] [Function and Effect]

[0112] In the laser processing apparatus 1 (and the laser processing method implemented in the laser processing apparatus 1), the beam shape 9 of the laser light L at the focused light spot C includes a central portion 90 and a first extension portion 91, a second extension portion 92, and a third extension portion 93 radially extending from the central portion 90, and the focused light spot C moves relatively along a line A set on the object 11 in a state where the central portion 90 has the highest intensity. At this time, by adjusting the direction of the beam shape 9 relative to the line A, etc., it is possible to adjust the state of at least one of the modified region 12 and the crack 13 formed in the object 11. Therefore, according to the laser processing apparatus 1, it is possible to form an appropriate modified region 12 and crack 13 in the object 11 according to the processing.

[0113] In the laser processing apparatus 1, when the modified region 12 is formed on the object 11 along the line A and the cracks 13 are formed on the object 11 from the modified region 12 along the first plane P1 parallel to both the incident direction of the laser light L and the extension direction of the line A, the control unit 6 causes the modulation pattern including the trefoil aberration pattern to be displayed on the spatial light modulator 7 in such a manner that the first extension portion 91 is located on the line A, the second extension portion 92 is located on one side with respect to the line A, and the third extension portion 93 is located on the other side with respect to the line A. Thus, the width of the cracks 13 in the incident direction of the laser light L can be reduced compared to, for example, a case where the modulation pattern does not include the trefoil aberration pattern.

[0114] In the laser processing apparatus 1, the control unit 6 displays a modulation pattern including a trefoil aberration pattern on the spatial light modulator 7 in such a manner that the first extension portion 91 is located at the front side of the direction in which the focused light spot C is relatively moved along the line A, and the second extension portion 92 and the third extension portion 93 are located at the rear side of the direction. Thus, not only the width of the crack 13 in the incident direction of the laser light L but also the width of the modified region 12 in the incident direction of the laser light L can be reduced. In addition, the crack 13 can be reliably prevented from meandering relative to the line A.

[0115] In the laser processing device 1, when the light-converging point C is relatively moved along each of the first line and the second line set as the line A on the object 11, when the direction in which the light-converging point C is relatively moved along the first line is different from the direction in which the light-converging point C is relatively moved along the second line, the control unit 6 switches the direction of the modulation pattern including the trefoil aberration pattern so that the first extension portion 91 is located on the front side of the direction in which the light-converging point C is relatively moved along the first line and the second line, and the second extension portion 92 and the third extension portion 93 are located on the rear side of the direction. Thus, even when the direction in which the light-converging point C is relatively moved along the first line is different from the direction in which the light-converging point C is relatively moved along the second line, it is possible to easily and reliably realize a state in which the first extension portion 91 is located on the front side of the direction in which the light-converging point C is relatively moved along the first line and the second line, and the second extension portion 92 and the third extension portion 93 are located on the rear side of the direction.

[0116] In the laser processing apparatus 1, the control unit 6 displays a modulation pattern of a trefoil aberration pattern including a first trefoil aberration intensity on the spatial light modulator 7 when the width of at least one of the modified region 12 and the crack 13 in the incident direction of the laser light L is set to a first width, and displays a modulation pattern of a trefoil aberration pattern including a second trefoil aberration intensity stronger than the first trefoil aberration intensity on the spatial light modulator 7 when the width of at least one of the modified region 12 and the crack 13 is set to a second width smaller than the first width. Thus, the width of at least one of the modified region 12 and the crack 13 in the incident direction of the laser light L can be set to an appropriate width according to the processing.

[0117] In the laser processing device 1, when the modified region 12 is formed on the object 11 along the line A and the cracks 13 are formed on the object 11 from the modified region 12 along the second surface P2 inclined with respect to the first surface P1 parallel to both the incident direction of the laser light L and the extending direction of the line A, when the second surface P2 is inclined in such a manner that the region on the side opposite to the incident side of the laser light L is located on one side in the direction perpendicular to the first surface P1, the control unit 6 causes the modulation pattern including the trefoil aberration pattern to be displayed on the spatial light modulator 7 in such a manner that the first extension portion 91 is located on one side with respect to the line A and the second extension portion 92 and the third extension portion 93 are located on the other side with respect to the line A. Thus, the cracks 13 extending from the modified region 12 can be inclined toward a desired side.

[0118] In the laser processing apparatus 1, when the light-converging point C is relatively moved along each of the first line and the second line set as the line A on the object 11, when the direction in which the light-converging point C is relatively moved along the first line is different from the direction in which the light-converging point C is relatively moved along the second line, the control unit 6 switches the direction of the modulation pattern including the trefoil aberration pattern so that the first extension portion 91 is located on one side with respect to each of the first line and the second line, and the second extension portion 92 and the third extension portion 93 are located on the other side with respect to each of the first line and the second line. Thus, even when the direction in which the light-converging point C is relatively moved along the first line is different from the direction in which the light-converging point C is relatively moved along the second line, it is possible to easily and reliably realize a state in which the first extension portion 91 is located on one side with respect to each of the first line and the second line, and the second extension portion 92 and the third extension portion 93 are located on the other side with respect to each of the first line and the second line.

[0119] In the laser processing apparatus 1, the control unit 6, when the angle between the first surface P1 and the second surface P2 is set to a first angle, causes the modulation pattern of the trefoil aberration pattern including the first trefoil aberration intensity to be displayed on the spatial light modulator 7, and when the angle is set to a second angle larger than the first angle, causes the modulation pattern of the trefoil aberration pattern including the second trefoil aberration intensity stronger than the first trefoil aberration intensity to be displayed on the spatial light modulator 7. Thus, the angle at which the cracks 13 extending from the modified region 12 are inclined can be set to an appropriate angle according to the processing.

[0120] [Modifications]

[0121] The present invention is not limited to the above-mentioned embodiments. For example, the spatial light modulator 7 is not limited to the reflective type, but may be a transmissive type. In addition, the optical system for transferring the image of the laser light L on the modulation surface 7a of the spatial light modulator 7 to the entrance pupil surface 33a of the focusing section 33 is not limited to the 4f lens unit 34 having a pair of lenses 34A and 34B, but may be an optical system including a first lens system (e.g., a cemented lens, three or more lenses, etc.) on the spatial light modulator 7 side and a second lens system (e.g., a cemented lens, three or more lenses, etc.) on the focusing section 33 side.

[0122] In addition, in the above-mentioned embodiment, the driving unit 4 drives the supporting unit 2, and the driving unit 5 drives the focusing unit 33 by driving the irradiating unit 3, but the driving unit of the present invention is not limited to such a method. As an example, the driving unit 4 may also move the supporting unit 2 in each of the Z direction, the X direction, and the Y direction, and rotate the supporting unit 2 with an axis parallel to the Z direction as the rotation axis. Alternatively, the driving unit 5 may also move the focusing unit 33 in each of the Z direction, the X direction, and the Y direction, and move the focusing unit 33 with an axis parallel to the Z direction as the center line. That is, the driving unit of the present invention may drive at least one of the supporting unit and the focusing unit.

[0123] In the above embodiment, the control unit 6 controls the support unit 2, the irradiation unit 3, and the driving units 4 and 5. However, the control unit of the present invention is not limited to this form. The control unit of the present invention only needs to control at least the spatial light modulator and the driving unit.

[0124] In addition, the laser processing method of displaying a modulation pattern including a three-leaf aberration pattern on the spatial light modulator 7 in a manner such that the first extension portion 91 is located on one side relative to the line A and the second extension portion 92 and the third extension portion 93 are located on the other side relative to the line A is also effective in the case of cutting a wafer into a plurality of quadrangular pyramid-shaped chips, cutting a plurality of circular pyramid-shaped wafers from a wafer, and the like.

[0125] Explanation of symbols

[0126] 1…laser processing device, 2…support portion, 4, 5…driving portion, 6…control portion, 7…spatial light modulator, 9…beam shape, 11…object, 12…modified region, 13…crack, 31…light source, 33…focusing portion, 90…center portion, 91…first extension portion, 92…second extension portion, 93…third extension portion, A…line, C…focusing spot, L…laser, P1…first surface, P2…second surface.

Claims

1. A laser processing device, wherein: have: a supporting portion that supports an object; a light source that emits laser light; a spatial light modulator that modulates the laser light emitted from the light source by displaying a modulation pattern; a light focusing unit for focusing the laser light modulated by the spatial light modulator onto the object; a driving unit configured to drive at least one of the supporting unit and the light focusing unit; and a control unit that controls at least the spatial light modulator and the driving unit, The control unit, causing the spatial light modulator to display a modulation pattern including a trefoil aberration pattern so that the beam shape of the laser light at the focal point of the laser light has a beam shape including a central portion and first, second, and third extended portions radially extending from the central portion, and having the highest intensity at the central portion; The driving unit drives at least one of the supporting unit and the focusing unit so as to relatively move the focused light spot along a line set on the object while the modulation pattern including the trefoil aberration pattern is displayed on the spatial light modulator.

2. The laser processing device according to claim 1, wherein: When a modified region is formed in the object along the line, and a crack is formed in the object from the modified region along a first surface parallel to both the incident direction of the laser light and the extending direction of the line, The control unit displays the modulation pattern including the trefoil aberration pattern on the spatial light modulator so that the first extension portion is located on the line, the second extension portion is located on one side of the line, and the third extension portion is located on the other side of the line.

3. The laser processing device according to claim 2, wherein: The control unit displays the modulation pattern including the trefoil aberration pattern on the spatial light modulator so that the first extension portion is located forward of a direction in which the focused light point moves relatively along the line and the second and third extension portions are located backward of the direction.

4. The laser processing device according to claim 3, wherein: When the light-converging point is relatively moved along each of a first line and a second line set as the lines on the object, if the direction in which the light-converging point is relatively moved along the first line is different from the direction in which the light-converging point is relatively moved along the second line, The control unit switches the direction of the modulation pattern including the trefoil aberration pattern so that the first extension portion is located forward of directions for relatively moving the focused light spot along the first line and the second line, and the second extension portion and the third extension portion are located backward of the directions.

5. The laser processing device according to any one of claims 2 to 4, wherein The control unit, displaying the modulation pattern of the trefoil aberration pattern including a first trefoil aberration intensity on the spatial light modulator when the width of at least one of the modified region and the crack in the incident direction of the laser light is set to a first width; When the at least one width is set to a second width smaller than the first width, the modulation pattern including the trefoil aberration pattern having a second trefoil aberration intensity stronger than the first trefoil aberration intensity is displayed on the spatial light modulator.

6. The laser processing device according to claim 1, wherein: In a case where a modified region is formed in the object along the line, and a crack is formed in the object along a second surface inclined relative to a first surface parallel to both the incident direction of the laser light and the extending direction of the line from the modified region, when the second surface is inclined so that a region on the side opposite to the incident side of the laser light is located on one side in a direction perpendicular to the first surface, The control unit displays the modulation pattern including the trefoil aberration pattern on the spatial light modulator so that the first extension portion is located on one side of the line and the second and third extension portions are located on the other side of the line.

7. The laser processing device according to claim 6, wherein: When the light-converging point is relatively moved along each of a first line and a second line set as the lines on the object, if the direction in which the light-converging point is relatively moved along the first line is different from the direction in which the light-converging point is relatively moved along the second line, The control unit switches the orientation of the modulation pattern including the trefoil aberration pattern so that the first extension portion is located on the one side relative to each of the first line and the second line, and the second extension portion and the third extension portion are located on the other side relative to each of the first line and the second line.

8. The laser processing device according to claim 6 or 7, wherein: The control unit, When the angle between the first surface and the second surface is set to a first angle, the modulation pattern including the trefoil aberration pattern having a first trefoil aberration intensity is displayed on the spatial light modulator; When the angle is set to a second angle larger than the first angle, the modulation pattern including the trefoil aberration pattern having a second trefoil aberration intensity stronger than the first trefoil aberration intensity is displayed on the spatial light modulator.

9. A laser processing method, wherein: It is a laser processing method implemented in a laser processing device. The laser processing device comprises: a supporting portion that supports an object; a light source that emits laser light; a spatial light modulator that modulates the laser light emitted from the light source by displaying a modulation pattern; a light focusing unit for focusing the laser light modulated by the spatial light modulator onto the object; a driving unit that drives at least one of the supporting unit and the focusing unit, The laser processing method comprises: a step of causing the spatial light modulator to display a modulation pattern including a trefoil aberration pattern so that the beam shape of the laser light at the focal point of the laser light has a beam shape including a central portion and first, second, and third extended portions radially extending from the central portion, and having the highest intensity at the central portion; and The step of causing the driving section to drive at least one of the supporting section and the focusing section so as to relatively move the focusing point along a line set on the object while the modulation pattern including the trefoil aberration pattern is displayed on the spatial light modulator.

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