Laser processing apparatus and laser processing method

Abstract

To provide a laser processing apparatus and a laser processing method, capable of reducing damage caused by leak light.SOLUTION: An object 11 includes: a first surface 11a to be an incidence surface of laser light L; a second surface 11b on the opposite side to the first surface 11a; and a first area R1 and a second area R2 aligned on the second surface 11b. A line A is set on the object 11 so as to pass between the first area R1 and the second area R2. A control part 6 performs a first irradiation treatment of irradiating the object 11 with the laser light L while relatively moving a condensed spot C1 along the line A in a state of positioning the condensed spot C1 of the laser light L in a Z direction at a first Z position on the second surface 11b side. In the first irradiation treatment, the control part 6 makes a beam shape of the condensed spot C1 in a YZ surface into a tilted shape tilted in the Z direction on a side closer to the first surface 11a than at least a center Ca of the condensed spot C1.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present disclosure relates to a laser processing apparatus and a laser processing method. [Background technology]

[0002] Patent Document 1 describes a laser dicing device. This laser dicing device includes a stage for moving a wafer, a laser head for irradiating the wafer with laser light, and a control unit for controlling each unit. The laser head includes a laser light source for emitting a processing laser light for forming a modified region inside the wafer, a dichroic mirror and a condenser lens arranged in this order on the optical path of the processing laser light, and an AF device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5743123 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, when a modified region is formed inside a wafer by irradiating the wafer with laser light, a part of the laser light may escape from the surface of the wafer opposite to the surface of the wafer where the laser light is incident (so-called leakage light may occur). This leakage light may cause damage to devices and the like formed on the surface of the wafer opposite to the surface of the wafer where the laser light is incident.

[0005] In view of the above, an object of the present disclosure is to provide a laser processing apparatus and a laser processing method that are capable of reducing the effects of damage caused by stray light. [Means for solving the problem]

[0006] The laser processing apparatus according to the present disclosure includes a support section for supporting an object, a light source for outputting laser light, a spatial light modulator for modulating the laser light output from the light source according to a modulation pattern and outputting the modulated laser light, a focusing lens for focusing the laser light output from the spatial light modulator toward the object and forming a focused spot of the laser light on the object, a moving section for moving the focused spot relatively to the object, and a control section for controlling at least the light source, the spatial light modulator, and the moving section, wherein the object includes a first surface which is an incidence surface of the laser light, a second surface opposite to the first surface, and first and second regions arranged on the second surface, and a line for relatively moving the focused spot so as to pass between the first and second regions is provided. a first irradiation process for irradiating the laser light to the object while moving the focused spot relatively along the line in a state in which the focused spot is positioned at a first Z position on the second surface side of the first surface in a Z direction intersecting the first surface and the second surface by controlling the light source, the spatial light modulator, and the moving unit, and in the first irradiation process, the control unit controls the modulation pattern to be displayed on the spatial light modulator so that the beam shape of the focused spot in a YZ plane including a Y direction and a Z direction intersecting the line and the Z direction becomes an inclined shape with respect to the Z direction, at least on the first surface side of the center of the focused spot.

[0007] A laser processing method according to the present disclosure is a laser processing method for irradiating laser light to an object including a first surface, a second surface opposite the first surface, and a first region and a second region arranged along the second surface, with a line set to pass between the first region and the second region, the method including a first irradiation step of irradiating the object with laser light while moving the focused spot relatively along the line with a state in which the focused spot of the laser light is positioned at a first Z position closer to the second surface side than the first surface in a Z direction intersecting the first and second surfaces, wherein at least a portion of the first and second regions on the line side have structures different from each other, and in the first irradiation step, the laser light is modulated so that the beam shape of the focused spot in a YZ plane including a Y direction and a Z direction intersecting the line and the Z direction becomes an inclined shape inclined with respect to the Z direction, at least on the first surface side of the center of the focused spot.

[0008] In this device and method, the laser beam is irradiated onto the object by relatively moving the focused spot of the laser beam along a line set on the object. The object includes a first surface which is the incident surface of the laser beam, a second surface opposite to the first surface, and a first region and a second region arranged along the second surface. The line along which the focused spot is relatively moved is set to pass between the first region and the second region. Then, when irradiating the laser beam, the beam shape of the focused spot in the YZ plane is inclined with respect to the Z direction at least on the first surface side from the center of the focused spot. According to the knowledge of the present inventor, by making the beam shape inclined in this way, it is possible to unevenly distribute damage caused by light leakage according to the inclination direction.

[0009] That is, when the inclination shape of the focused spot in the YZ plane is made to be from the second region to the first region as it goes from the first surface to the second surface, the damage caused by the light leakage can be unevenly distributed to the first region side. On the other hand, when the inclination shape of the focused spot in the YZ plane is made to be from the first region to the second region as it goes from the first surface to the second surface, the damage caused by the light leakage can be unevenly distributed to the second region side. Here, the first region and the second region of the object have different structures from each other at least in a part on the line side. Therefore, according to this device and method, by controlling the inclination direction of the focused spot, it is possible to unevenly distribute the damage caused by the light leakage to the region opposite the region in which the part is relatively vulnerable to the light leakage in the first region and the second region. As a result, according to this device and method, the influence of the damage caused by the light leakage can be reduced.

[0010] In the laser processing apparatus according to the present disclosure, the control unit controls the light source, the spatial light modulator, and the moving unit to execute a second irradiation process in which the laser light is irradiated onto the target while relatively moving the focused spot along the line in a state in which the focused spot is positioned at a second Z position farther from the second surface in the Z direction than the first Z position, and in the second irradiation process, the control unit may control the spatial light modulator to make the beam shape of the focused spot in the YZ plane a non-inclined shape along the Z direction. In this case, at the second Z position which is farther from the second surface on which the first and second regions are arranged and where the influence of light leakage to the second surface side is small, the beam shape of the focused spot of the laser light is made a non-inclined shape along the Z direction, making it possible to suitably extend a crack in the Z direction from the modified region formed near the second Z position.

[0011] In the laser processing device according to the present disclosure, the first region and the second region are each a semiconductor device, and the second region is provided with a wiring portion in a part thereof, and in the first irradiation process, the control unit may control the modulation pattern displayed by the spatial light modulator so that the beam shape of the focused spot in the YZ plane is an inclined shape from the second region toward the first region as it moves from the first surface to the second surface, at least on the first surface side of the center of the focused spot. In general, in semiconductor devices, the wiring portion is easily damaged by the leakage light. Therefore, by controlling the inclined shape as described above, the damage caused by the leakage light is unevenly distributed on the first region side opposite to the second region where the wiring portion is provided, and the influence of the damage caused by the leakage light can be reliably reduced.

[0012] In the laser processing apparatus according to the present disclosure, the second region is an active region, the first region is a region different from the active region, and in the first irradiation process, the control unit may control the modulation pattern displayed by the spatial light modulator so that the beam shape of the focused spot in the YZ plane is an inclined shape from the second region toward the first region as it moves from the first surface to the second surface, at least on the first surface side of the center of the focused spot. In this case, by controlling the inclined shape as described above, damage caused by the escape light can be concentrated on the first surface side opposite the second region, which is the active area, and the influence of damage caused by the escape light can be reliably reduced.

[0013] In the laser processing device according to the present disclosure, the modulation pattern may include a coma aberration pattern for imparting coma aberration to the laser beam, and in the first irradiation process, the control unit may control the coma aberration caused by the coma aberration pattern to make the beam shape an inclined shape. In this way, by controlling the coma aberration imparted to the laser beam, it is possible to control the inclination shape of the focused spot. Effect of the Invention

[0014] According to the present disclosure, it is possible to provide a laser processing apparatus and a laser processing method capable of reducing the influence of damage caused by stray light. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a laser processing device according to one embodiment. [Diagram 2] FIG. 2 is a schematic diagram showing the configuration of the laser irradiation unit shown in FIG. [Diagram 3] FIG. 3 is a schematic diagram showing the 4f lens unit and the like shown in FIG. [Figure 4] FIG. 4 is a schematic diagram showing a cross section of the spatial light modulator shown in FIG. [Diagram 5] FIG. 5 is a diagram showing an example of a target object. [Figure 6] FIG. 6 is a diagram showing a step of a laser processing method according to an embodiment. [Figure 7] FIG. 7 is a diagram showing another step of the laser processing method according to the embodiment. [Figure 8] FIG. 8 is a diagram showing the shape of the focused spot and the influence of leaking light. [Figure 9] FIG. 9 is a diagram showing how the spherical aberration correction pattern is offset. [Figure 10] FIG. 10 is a diagram showing changes in the beam shape when the offset amount of the spherical aberration correction pattern or the level of coma aberration of the coma aberration pattern is changed in multiple steps. [Figure 11] FIG. 11 shows the profile of each focused spot in the XY plane. [Figure 12] FIG. 12 is a photograph showing an example of the processing result according to the level of coma aberration. [Figure 13] FIG. 13 is a diagram showing an example of a modulation pattern. [Figure 14] FIG. 14 is a diagram showing the intensity distribution on the entrance pupil plane of the condenser lens and the beam shape of the condensed spot. [Figure 15] FIG. 15 is a diagram showing the beam shape of the focused spot and the observation results of the intensity distribution of the focused spot. [Figure 16] FIG. 16 is a diagram showing an example of a modulation pattern. [Figure 17] FIG. 17 is a diagram showing another example of an asymmetric modulation pattern. [Figure 18] FIG. 18 is a diagram showing the intensity distribution on the entrance pupil plane of the condenser lens and the beam shape of the condensed spot. [Figure 19] FIG. 19 is a schematic cross-sectional view showing a focused spot according to a modified example. [Figure 20] FIG. 20 is a diagram showing an object according to a modified example. [Figure 21] FIG. 21 is a diagram showing an object according to another modified example. [Figure 22] FIG. 22 is a diagram showing the beam shape of a focused spot. [Diagram 23] FIG. 23 is a diagram showing the beam shape of a focused spot. [Figure 24] FIG. 24 is a diagram for explaining the processing result. [Diagram 25] FIG. 25 is a diagram showing an object according to still another modified example. [Figure 26] FIG. 26 is a diagram for explaining a method for forming an oblique crack. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] An embodiment will be described in detail below with reference to the drawings. In each drawing, the same or corresponding parts are given the same reference numerals, and duplicated explanations may be omitted. In addition, each drawing may show an orthogonal coordinate system defined by an X-axis, a Y-axis, and a Z-axis.

[0017] Fig. 1 is a schematic diagram showing the configuration of a laser processing apparatus according to one embodiment. As shown in Fig. 1, the laser processing apparatus 1 includes a stage (support unit) 2, a laser irradiation unit 3, drive units (movement units) 4 and 5, and a control unit 6. The laser processing apparatus 1 is an apparatus for forming a modified region 12 in an object 11 by irradiating the object 11 with laser light L.

[0018] The stage 2 supports the object 11, for example, by holding a film attached to the object 11. The stage 2 is rotatable about an axis parallel to the Z direction. The stage 2 may be movable along both the X direction and the Y direction. The X direction and the Y direction are a first horizontal direction and a second horizontal direction that intersect (are perpendicular to) each other, and the Z direction is a vertical direction.

[0019] The laser irradiation unit 3 focuses laser light L, which is transparent to the object 11, and irradiates the object 11. When the laser light L is focused inside the object 11 supported by the stage 2, the laser light L is particularly absorbed in a portion corresponding to a focused spot C (for example, a center Ca described later) of the laser light L, and a modified region 12 is formed inside the object 11. The focused spot C, which will be described in detail later, is a position where the beam intensity of the laser light L is highest or a region within a predetermined range from the center of gravity of the beam intensity.

[0020] The modified region 12 is a region that differs from the surrounding non-modified region in terms of density, refractive index, mechanical strength, and other physical properties. Examples of the modified region 12 include a melting treatment region, a crack region, a dielectric breakdown region, and a refractive index change region. The modified region 12 can be formed such that a crack extends from the modified region 12 to the incident side of the laser light L and to the opposite side. Such modified region 12 and cracks are used, for example, to cut the object 11.

[0021] As an example, when the stage 2 is moved along the X direction and the focused spot C is moved along the X direction relative to the object 11, multiple modified spots 12s are formed in a row along the X direction. One modified spot 12s is formed by irradiating one pulse of laser light L. One row of modified regions 12 is a collection of multiple modified spots 12s lined up in a row. Adjacent modified spots 12s may be connected to each other or separated from each other depending on the relative moving speed of the focused spot C with respect to the object 11 and the repetition frequency of the laser light L.

[0022] The driving unit 4 includes a first moving unit 41 that moves the stage 2 in one direction in a plane intersecting (orthogonal) with the Z direction, and a second moving unit 42 that moves the stage 2 in another direction in a plane intersecting (orthogonal) with the Z direction. As an 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 driving unit 4 also rotates the stage 2 around an axis parallel to the Z direction as a rotation axis. The driving unit 5 supports the laser irradiation unit 3. The driving unit 5 moves the laser irradiation unit 3 along the X direction, the Y direction, and the Z direction. When the stage 2 and / or the laser irradiation unit 3 is moved in a state in which the focused spot C of the laser light L is formed, the focused spot C is moved relative to the object 11. That is, the driving units 4 and 5 are moving units that move at least one of the stage 2 and the laser irradiation unit 3 so that the focused spot C of the laser light L moves relative to the object 11.

[0023] The control unit 6 controls the operations of the stage 2, the laser irradiation unit 3, and the driving units 4 and 5. The control unit 6 has a processing unit, a memory unit, and an input receiving unit (not shown). The processing unit is configured as a computer device including a processor, memory, storage, a communication device, etc. In the processing unit, the processor executes software (programs) loaded into the memory, etc., and controls reading and writing of data in the memory and storage, as well as communication by the communication device. The memory unit is, for example, a hard disk, and stores various data. The input receiving unit is an interface unit that displays various information and receives input of various information from the user. The input receiving unit constitutes a GUI (Graphical User Interface).

[0024] FIG. 2 is a schematic diagram showing the configuration of the laser irradiation unit shown in FIG. 1. FIG. 2 shows a virtual line A indicating the planned laser processing. As shown in FIG. 2, the laser irradiation unit 3 has a light source 31, a spatial light modulator 7, a condenser lens 33, and a 4f lens unit 34. The light source 31 outputs the laser light L, for example, by a pulse oscillation method. Note that the laser irradiation unit 3 may be configured not to have the light source 31 and to introduce the laser light L from outside the laser irradiation unit 3. The spatial light modulator 7 modulates the laser light L output from the light source 31. The condenser lens 33 condenses the laser light L modulated by the spatial light modulator 7 and output from the spatial light modulator 7 toward the object 11.

[0025] 3, the 4f lens unit 34 has a pair of lenses 34A, 34B arranged on the optical path of the laser light L traveling from the spatial light modulator 7 to the condenser lens 33. The pair of lenses 34A, 34B configure a double-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 condenser lens 33 are in an imaging relationship. As a result, an image of the laser light L on the modulation surface 7a of the spatial light modulator 7 (an image of the laser light L modulated by the spatial light modulator 7) is transferred (imaged) on the entrance pupil surface 33a of the condenser lens 33. Note that Fs in the figure indicates a Fourier plane.

[0026] 4, the spatial light modulator 7 is a reflective liquid crystal (LCOS: Liquid Crystal on Silicon) spatial light modulator (SLM: Spatial Light Modulator). The spatial light modulator 7 is configured by laminating 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 in this order on a semiconductor substrate 71.

[0027] The semiconductor substrate 71 is, for example, a silicon substrate. The drive circuit layer 72 configures 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, for example, a metal material such as aluminum. A voltage is applied to each pixel electrode 73a by the drive circuit layer 72.

[0028] 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 on the reflective film 74 side, and the alignment film 77 is provided on the surface of the liquid crystal layer 76 opposite the reflective film 74. Each alignment film 75, 77 is formed of, for example, a polymer material such as polyimide, and the contact surface of each alignment film 75, 77 with the liquid crystal layer 76 is subjected to, for example, rubbing treatment. The alignment films 75, 77 align the liquid crystal molecules 76a contained in the liquid crystal layer 76 in a fixed direction.

[0029] 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 and the like sandwiched therebetween. 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 the laser light L.

[0030] In the spatial light modulator 7 configured as 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 the electric field is formed, the arrangement direction of the liquid crystal molecules 76a in the liquid crystal layer 76 changes 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 a state in which the modulation pattern is displayed on the liquid crystal layer 76. The modulation pattern is for modulating the laser light L.

[0031] That is, when the laser light L enters the liquid crystal layer 76 from the outside through the transparent substrate 79 and the transparent conductive film 78 while the modulation pattern is displayed on the liquid crystal layer 76, is reflected by the reflective film 74, and is emitted from the liquid crystal layer 76 to the outside through the transparent conductive film 78 and the transparent substrate 79, the laser light L is modulated according to the modulation pattern displayed on the liquid crystal layer 76. In this way, the spatial light modulator 7 allows modulation of the laser light L (e.g., modulation of the intensity, amplitude, phase, polarization, etc. of the laser light L) by appropriately setting the modulation pattern to be displayed on the liquid crystal layer 76. The modulation surface 7a shown in FIG. 3 is, for example, the liquid crystal layer 76.

[0032] As described above, the laser light L output from the light source 31 is incident on the condenser lens 33 via the spatial light modulator 7 and the 4f lens unit 34, and is focused by the condenser lens 33 inside the target 11, thereby forming the modified region 12 and a crack extending from the modified region 12 in the target 11 at the focused spot C. Furthermore, the control unit 6 controls the drive units 4 and 5 to move the focused spot C relative to the target 11, thereby forming the modified region 12 and the crack along the movement direction of the focused spot C.

[0033] FIG. 5 is a diagram showing an example of an object. FIG. 5(a) is a plan view, and FIG. 5(b) is a cross-sectional view taken along line Vb-Vb in FIG. 5(a). In FIG. 5(b), hatching is omitted (the same applies to each cross-sectional view below). As shown in FIG. 5, the object 11 includes a first surface 11a and a second surface 11b opposite to the first surface 11a. The object 11 is supported by the stage 2 so that the first surface 11a and the second surface 11b intersect (are perpendicular to) the Z direction and so that the first surface 11a faces the laser irradiation unit 3. Therefore, in the object 11, the first surface 11a becomes the incident surface of the laser light L.

[0034] The target object 11 includes a plurality of semiconductor devices 11D arranged two-dimensionally along the second surface 11b. The semiconductor devices 11D include wiring portions W made of, for example, metal. The wiring portions W are arranged on one side (here, the positive side in the Y direction) of one semiconductor device 11D in a plan view. Also, each of the semiconductor devices 11D is arranged in the same direction in a plan view. Therefore, of a pair of semiconductor devices 11D adjacent to each other in the Y direction, one semiconductor device 11D does not have the wiring portion W in a portion P1 facing the other semiconductor device 11D, and the other semiconductor device 11D has the wiring portion W in a portion P2 facing the one semiconductor device 11D.

[0035] Here, one semiconductor device 11D and an area on the second surface 11b where the semiconductor device 11D is provided are referred to as a first region R1, and the other semiconductor device 11D and an area on the second surface 11b where the semiconductor device 11D is provided are referred to as a second region R2. A street region Rs is interposed between the first region R1 and the second region R2, i.e., between the adjacent semiconductor devices 11D. The line A is set in the street region Rs so as to pass between the first region R1 and the second region R2. Therefore, the portions P1 and P2 on the line A side of the first region R1 and the second region R2 have structures different from each other in whether or not they include at least a wiring portion W.

[0036] Laser processing is performed on such an object 11 as follows. FIG. 6 is a diagram showing one step of a laser processing method according to one embodiment. FIG. 6(a) is a plan view, and FIG. 6(b) is a cross-sectional view along line VIb-VIb of FIG. 6(a). As shown in FIG. 6, first, while the laser light L is incident on the object 11 from the first surface 11a side, a focused spot C1 of the laser light L is formed at a first Z position in the Z direction inside the object 11. The first Z position is a position closer to the second surface 11b than the first surface 11a. In this state, the laser light L is irradiated onto the object 11 while the focused spot C1 of the laser light L is relatively moved in the X direction along the line A (step S101: first irradiation step).

[0037] In this step S101, the control unit 6 of the laser processing apparatus 1 controls the light source 31, the spatial light modulator 7, and the driving units 4 and 5 to perform a first irradiation process in which the laser light L is irradiated onto the object 11 while the focused spot C1 is relatively moved along the line A in a state in which the focused spot C1 is positioned at a first Z position closer to the second surface 11b than the first surface 11a in the Z direction. Thus, here, the X direction is set as the processing progress direction FD. As a result, a modified region 12a is formed along the line A inside the object 11 (at the first Z position). This step S101 and the first irradiation process can be performed sequentially for a plurality of lines A.

[0038] FIG. 7 is a diagram showing another step of the laser processing method according to an embodiment. FIG. 7(a) is a plan view, and FIG. 7(b) is a cross-sectional view along line VIIb-VIIb in FIG. 7(a). As shown in FIG. 7, the laser light L is then incident on the object 11 from the first surface 11a side, so that a condensed spot C2 of the laser light L is formed at a second Z position in the Z direction inside the object 11. The second Z position is a position closer to the first surface 11a than the first Z position. In this state, the laser light L is irradiated onto the object 11 while the condensed spot C2 of the laser light L is relatively moved in the X direction along the line A (step S102).

[0039] In this step S102, the control unit 6 of the laser processing apparatus 1 controls the light source 31, the spatial light modulator 7, and the driving units 4 and 5 to perform a second irradiation process in which the laser light L is irradiated onto the object 11 while moving the focused spot C2 relatively along the line A in a state in which the focused spot C2 is positioned at a second Z position in the Z direction that is farther from the second surface 11b than the first Z position. As a result, a modified region 12b is formed inside the object 11 (at the second Z position) along the line A. This step S102 and the second irradiation process can be performed sequentially for multiple lines A.

[0040] In the example of FIG. 7(b), two rows of modified regions 12b are formed closer to the first surface 11a than the modified regions 12a formed near the first Z position. All modified regions 12b are formed near the second Z position closer to the first surface 11a than the first Z position. In this manner, the modified regions 12b can be formed in any number of rows by irradiating the laser light L while positioning the focused spot C2 of the laser light L at two or more second Z positions. In other words, the first Z position is the position in the Z direction where the focused spot C1 is located when forming the modified region 12a closest to the second surface 11b when forming the multiple rows of modified regions 12 aligned in the Z direction.

[0041] Therefore, in step S101 and the first irradiation process, since the laser processing is performed by positioning the focused spot C1 closest to the second surface 11b side among the multiple laser processings, it is highly necessary to consider damage caused by light leaking from the focused spot C1 to the second surface 11b side, i.e., the semiconductor device 11D side. Therefore, in this embodiment, at least in step S101 and the first irradiation process, the shape of the focused spot C1 is made to be inclined. This point will be described in detail below.

[0042] FIG. 8 is a diagram showing the shape of the focused spot and the influence of the light leakage. FIG. 8(a) shows the beam shape of the focused spot C1 in the YZ plane. The Y direction is a direction intersecting (orthogonal to) both the X direction, which is the processing progress direction FD, and the Z direction. As shown in FIG. 8(a), in step S101 and the first irradiation process, the spatial light modulator 7 is used to modulate the laser light L, so that the beam shape of the focused spot C1 in the YZ plane is inclined with respect to the Z direction at least on the first surface 11a side of the center Ca of the focused spot C1. According to the knowledge of the present inventor, when the beam shape is inclined in this way, it is possible to unevenly distribute damage caused by the light leakage according to the inclination direction.

[0043] In this embodiment, the beam shape of the focused spot C1 is inclined toward the negative side of the Y direction with respect to the Z direction on the first surface 11a side from the center Ca, that is, from the second region R2 to the first region R1 as it moves from the first surface 11a to the second surface 11b (as it moves toward the negative side of the Z direction). In addition, in this embodiment, the beam shape of the focused spot C1 is also inclined toward the negative side of the Y direction with respect to the Z direction on the second surface 11b side from the center Ca, that is, from the first region R1 to the second region R2 as it moves from the first surface 11a to the second surface 11b (as it moves toward the negative side of the Z direction). As a result, the beam shape of the focused spot C1 in the YZ plane is an arc shape that is convex toward the positive side of the Y direction as a whole. The beam shape of the focused spot C1 in the YZ plane is the intensity distribution of the laser light L at the focused spot C1 in the YZ plane.

[0044] As shown in (b) of Figure 8, by controlling the inclination shape of the beam shape of the focused spot C1 as described above, the damage caused by the escape light Lt can be concentrated on the first region R1 side opposite the second region R2 in which the wiring part W is provided, and the effect of the escape light Lt on the wiring part W, which is susceptible to damage by the escape light Lt, can be reliably reduced.

[0045] Next, knowledge for making the beam shape of the focused spot C1 in the YZ plane into an inclined shape will be described. First, the definition of the focused spot C1 (the same applies to other focused spots) will be specifically described. Here, the focused spot C1 is an area within a predetermined range from the center Ca (for example, a range of ±25 μm from the center Ca in the Z direction). The center Ca is the position where the beam intensity is highest, or the position of the center of gravity of the beam intensity. The position of the center of gravity of the beam intensity is the position where the center of gravity of the beam intensity is located on the optical axis of the laser light L in a state where modulation is not performed by a modulation pattern that shifts the optical axis of the laser light L, such as a modulation pattern for branching the laser light L.

[0046] The position where the beam intensity is highest and the center of gravity of the beam intensity can be obtained as follows. That is, the laser light L is irradiated onto the object 11 while the output of the laser light L is set to a level (lower than the processing threshold) such that the modified region 12 is not formed on the object 11. At the same time, the reflected light of the laser light L from the surface of the object 11 opposite to the incident surface of the laser light L (here, the second surface 11b) is captured by a camera at a plurality of positions F1 to F7 in the Z direction shown in FIG. 15. This makes it possible to obtain the position where the beam intensity is highest and the center of gravity based on the obtained images. The modified region 12 is formed near this center Ca.

[0047] In order to make the beam shape at the focused spot C1 an inclined shape, there is a method of offsetting the modulation pattern. More specifically, various patterns such as a distortion correction pattern for correcting wavefront distortion, a grating pattern for branching laser light, a slit pattern, an astigmatism pattern, a coma aberration pattern, and a spherical aberration correction pattern are displayed on the spatial light modulator 7 (a pattern in which these are superimposed is displayed). Of these, as shown in Fig. 9, the beam shape at the focused spot C1 can be adjusted by offsetting the spherical aberration correction pattern Ps.

[0048] In the example of Fig. 9, on the modulation plane 7a, the center Pc of the spherical aberration correction pattern Ps is offset by an offset amount Oy1 on the negative side in the Y direction with respect to the center Lc (of the beam spot) of the laser light L. As described above, the modulation plane 7a is transferred to 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 on 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 on the positive side in the Y direction from the center Lc of the laser light L and the center of the entrance pupil plane 33a (which coincides with the center Lc here).

[0049] In this way, by offsetting the spherical aberration correction pattern Ps, the beam shape of the condensed spot C1 of the laser light L is deformed into an arc-shaped inclined shape as shown in FIG. 8(a). Offsetting the spherical aberration correction pattern Ps as described above corresponds to giving coma aberration to the laser light L. Therefore, the beam shape of the condensed spot C1 may be made into an inclined shape by including a coma aberration pattern for giving coma aberration to the laser light L in the modulation pattern of the spatial light modulator 7. That is, the modulation pattern may include a coma aberration pattern for giving coma aberration to the laser light L, and in step S101 and the first irradiation process, the control unit 6 may control the coma aberration due to the coma aberration pattern to make the beam shape into the inclined shape. Note that, as the coma aberration pattern, a pattern equivalent to the ninth term of the Zernike polynomial (Y component of third-order coma aberration) and in which coma aberration occurs in the Y direction may be used.

[0050] Fig. 10 is a diagram showing a change in beam shape when the offset amount of the spherical aberration correction pattern or the level of coma aberration of the coma aberration pattern is changed in multiple stages. "Offset [pixel] SLM plane" in Fig. 10 indicates the offset amount on the modulation surface 7a. Also, "(third-order) coma aberration" indicates the magnitude of third-order coma aberration corresponding to the offset amount of the spherical aberration correction pattern Ps. As described above, here, the sign of the offset amount of the spherical aberration correction pattern Ps on the modulation surface 7a is reversed to the sign of the offset amount of the spherical aberration correction pattern Ps on the entrance pupil surface 33a.

[0051] Also, "BE (μm)" is the correction amount of the spherical aberration correction pattern Ps, "Z [μm]" is the focusing position of the laser light L in the Z direction, and "CP [μm]" is the focusing correction amount. As shown in Fig. 10, by gradually changing the offset amount (of the center Pc) of the spherical aberration correction pattern Ps or by gradually changing the level of coma aberration of the coma aberration pattern, the beam shape of the focused spot C1 can be gradually changed.

[0052] Next, among the multiple focused spots shown in Fig. 10, a focused spot C1a when the coma aberration level is "4", a focused spot C1b when the coma aberration level is "1", and a focused spot C1c when the coma aberration level is "0" (when no coma aberration is applied) will be compared. Fig. 11 shows the profile of each focused spot in the XY plane (at position Qa). As shown in Fig. 11, it can be seen that as the level of coma aberration increases from the focused spot C1c to the focused spot C1a, the beam intensity distribution in the XY plane changes from a uniform state to a biased state.

[0053] Fig. 12 is a photograph showing an example of a processing result according to the level of coma aberration. Fig. 12(a) shows the processing result when the coma aberration level is "4" (focus spot C1a), Fig. 12(b) shows the processing result when the coma aberration level is "1" (focus spot C1b), and Fig. 12(c) shows the processing result when the coma aberration level is "0" (focus spot C1c). In the examples of Fig. 12(a) and (b), the damage Dt caused by the leakage light is definitely concentrated in the first region R1, and no damage Dt occurs in the second region R2.

[0054] On the other hand, in the example of FIG. 12(c), the damage Dt caused by the escaping light Lt is not unevenly distributed, and the damage Dt occurs in both the first region R1 and the second region R2. From this result, it can be understood that the effect of the damage Dt caused by the escaping light Lt can be controlled by making the beam shape of the focused spot C1 an inclined shape as described above. In the example of FIG. 12, the damage Dt is visualized by forming a metal film on the second surface 11b of the object 11 instead of the semiconductor device 11D. Also, the damage Dt is considered to be so-called splash.

[0055] As described above, at least in step S101 and the first irradiation process, the control unit 6 controls the modulation pattern to be displayed on the spatial light modulator 7 so that the beam shape of the focused spot C1 in the YZ plane including the Y and Z directions intersecting the line A and the Z direction becomes an inclined shape inclined with respect to the Z direction at least on the first surface 11a side from the center Ca of the focused spot C1. More specifically, in step S101 and the first irradiation process, the control unit 6 controls the modulation pattern to be displayed on the spatial light modulator 7 so that the beam shape of the focused spot C1 in the YZ plane becomes an inclined shape from the second region R2 toward the first region R1 as it moves from the first surface 11a to the second surface 11b at least on the first surface 11a side from the center Ca of the focused spot C1.

[0056] On the other hand, in step S102 and the second irradiation process, the control unit 6 may control the spatial light modulator 7 so that the beam shape of the focused spot C2 of the laser light L is inclined, as in step S101 and the first irradiation process. However, in step S102 and the second irradiation process, the processing is performed by positioning the focused spot C2 at a second Z position relatively far from the second surface 11b, so there is little need to consider damage caused by light leaking from the focused spot C2 to the second surface 11b side, i.e., the semiconductor device 11D side. Therefore, in this embodiment, in step S102 and the second irradiation process, the control unit 6 controls the spatial light modulator 7 to make the beam shape of the focused spot C2 in the YZ plane a non-inclined shape along the Z direction. The non-inclined focused spot C2 can be formed into a shape like the focused spot C1c by setting the level of coma aberration of the modulation pattern displayed on the spatial light modulator 7 to "0", for example.

[0057] As described above, in the laser processing apparatus 1 and the laser processing method according to the present embodiment, the laser light L is irradiated onto the object 11 by relatively moving the focused spot C of the laser light L along the line A set on the object 11. The object 11 includes a first surface 11a which is an incident surface of the laser light L, a second surface 11b opposite to the first surface 11a, and a first region R1 and a second region R2 arranged along the second surface 11b. The line A for relatively moving the focused spot C is set to pass between the first region R1 and the second region R2. Then, when irradiating the laser light L, the beam shape of the focused spot C1 in the YZ plane is inclined with respect to the Z direction at least on the first surface 11a side from the center Ca of the focused spot C1. By making the beam shape inclined in this way, it is possible to unevenly distribute the damage Dt caused by the escape light Lt according to the inclination direction.

[0058] That is, when the inclination shape of the focused spot C1 in the YZ plane is such that it is directed from the second region R2 to the first region R1 as it moves from the first surface 11a to the second surface 11b, the damage Dt caused by the escaping light Lt can be unevenly distributed on the first region R1 side. On the other hand, when the inclination shape of the focused spot C1 in the YZ plane is such that it is directed from the first region R1 to the second region R2 as it moves from the first surface 11a to the second surface 11b, the damage Dt caused by the escaping light Lt can be unevenly distributed on the second region R2 side.

[0059] Here, the first region R1 and the second region R2 of the object 11 have different structures at least in the line side portions P1, P2. Therefore, according to the laser processing apparatus 1 and the laser processing method of this embodiment, by controlling the inclination direction of the focused spot C1, it is possible to unevenly distribute the damage Dt caused by the stray light Lt in the region opposite to the region in which the portions P1, P2 of the first region R1 and the second region R2 are relatively vulnerable to the stray light Lt. As a result, according to the laser processing apparatus 1 and the laser processing method of this embodiment, it is possible to reduce the influence of the damage Dt caused by the stray light Lt.

[0060] In the laser processing apparatus 1 according to the present embodiment, the control unit 6 controls the light source 31, the spatial light modulator 7, and the driving units 4 and 5 to perform a second irradiation process in which the laser light L is irradiated onto the object 11 while the focused spot C2 is moved relatively along the line A in a state in which the focused spot C2 is positioned at a second Z position farther from the second surface 11b in the Z direction than the first Z position. In the second irradiation process, the control unit 6 controls the spatial light modulator 7 to make the beam shape of the focused spot C2 in the YZ plane a non-inclined shape along the Z direction. In this way, at the second Z position farther from the second surface 11b on which the first region R1 and the second region R2 are arranged and where the influence of the light leakage Lt to the second surface 11b side is small, the beam shape of the focused spot C2 of the laser light L is made a non-inclined shape along the Z direction, so that it is possible to suitably extend a crack (vertical crack) in the Z direction from the modified region 12b formed near the second Z position.

[0061] In the laser processing apparatus 1 according to the present embodiment, the first region R1 and the second region R2 are semiconductor devices 11D, and the second region R2 has a wiring portion W provided in a portion P2. In the first irradiation process, the control unit 6 controls the modulation pattern displayed by the spatial light modulator 7 so that the beam shape of the focused spot C1 in the YZ plane is an inclined shape from the second region R2 toward the first region R1 as it moves from the first surface 11a to the second surface 11b at least on the first surface 11a side of the center Ca of the focused spot C1. In general, in the semiconductor device 11D, the wiring portion W is easily damaged by the leakage light Lt. Therefore, by controlling the inclined shape as described above, the damage Dt caused by the leakage light Lt can be unevenly distributed on the first region R1 side opposite to the second region R2 where the wiring portion W is provided, and the effect of the damage Dt caused by the leakage light Lt can be reliably reduced.

[0062] Furthermore, in the laser processing apparatus 1 according to this embodiment, the modulation pattern includes a coma aberration pattern for imparting coma aberration to the laser light L, and in the first irradiation process, the control unit 6 may control the coma aberration caused by the coma aberration pattern to make the beam shape an inclined shape. In this way, by controlling the coma aberration imparted to the laser light L, it is possible to control the inclined shape of the focused spot C1. [Variations]

[0063] The above embodiment describes an example of the laser processing apparatus and the laser processing method according to the present disclosure. Therefore, the laser processing apparatus and the laser processing method according to the present disclosure can be modified from the above.

[0064] In the above embodiment, when the beam shape of the focused spot C of the laser light L is made to be an inclined shape, the offset of the spherical aberration correction pattern Ps and the coma aberration are utilized. However, the control of the beam shape is not limited to the above example. Next, another example for making the beam shape into an inclined shape will be described. As shown in (a) of FIG. 13, the laser light L may be modulated by a modulation pattern PG1 asymmetric with respect to the axis Ax along the X direction which is the processing progress direction FD, to make the beam shape of the focused spot C into an inclined shape. The modulation pattern PG1 includes a grating pattern Ga on the negative side of the Y direction from the axis Ax along the X direction passing through the center Lc of the beam spot of the laser light L in the Y direction, and includes a non-modulated region Ba on the positive side of the axis Ax in the Y direction. In other words, the modulation pattern PG1 includes a grating pattern Ga only on the negative side of the axis Ax in the Y direction. Note that (b) of FIG. 13 is obtained by inverting the modulation pattern PG1 of (a) of FIG. 13 so as to correspond to the entrance pupil surface 33a of the focusing lens 33.

[0065] Fig. 14(a) shows the intensity distribution of the laser light L on the entrance pupil plane 33a of the focusing lens 33. As shown in Fig. 14(a), by using such a modulation pattern PG1, the portion of the laser light L that is incident on the spatial light modulator 7 and that is modulated by the grating pattern Ga does not enter the entrance pupil plane 33a of the focusing lens 33. As a result, as shown in Fig. 14(b) and Fig. 15, the beam shape of the focused spot C in the YZ plane can be made into an inclined shape whose entirety is inclined in one direction with respect to the Z direction.

[0066] That is, in this case, the beam shape of the focused spot C is inclined toward the negative side of the Y direction with respect to the Z direction on the first surface 11a side from the center Ca of the focused spot C. That is, on the first surface 11a side from the center Ca, the beam shape is inclined from the second region R2 to the first region R1 as it moves from the first surface 11a to the second surface 11b (as it moves toward the negative side of the Z direction). Also, in this case, on the second surface 11b side from the center Ca of the focused spot C, the beam shape is inclined toward the positive side of the Y direction with respect to the Z direction. That is, on the second surface 11b side from the center Ca, the beam shape is also inclined from the second region R2 to the first region R1 as it moves from the first surface 11a to the second surface 11b (as it moves toward the negative side of the Z direction).

[0067] In this case, the damage Dt caused by the stray light Lt is concentrated on the first region R1 side. In contrast, to cause the damage Dt caused by the stray light Lt to be concentrated on the second region R2 side, the positions of the grating pattern Ga and the non-modulated region Ba in the modulation pattern PG1 may be interchanged. Each diagram in FIG. 15(b) shows the intensity distribution in the XY plane of the laser light L at each position F1 to F7 in the Z direction shown in FIG. 15(a), which is an actual observation result by a camera.

[0068] Furthermore, as modulation patterns asymmetric with respect to the axis Ax, modulation patterns PG2, PG3, and PG4 shown in Fig. 16 can also be adopted. The modulation pattern PG2 includes a non-modulation region Ba and a grating pattern Ga arranged in order in a direction away from the axis Ax on the negative side of the axis Ax in the Y direction, and includes a non-modulation region Ba on the positive side of the axis Ax in the Y direction. In other words, the modulation pattern PG2 includes a grating pattern Ga in a part of the region on the negative side of the axis Ax in the Y direction.

[0069] The modulation pattern PG3 includes non-modulated regions Ba and grating patterns Ga arranged in sequence in a direction away from the axis Ax on the negative side of the axis AX in the Y direction, and also includes non-modulated regions Ba and grating patterns Ga arranged in sequence in a direction away from the axis Ax on the positive side of the axis Ax in the Y direction. The modulation pattern PG3 is made asymmetric with respect to the axis Ax by varying the proportions of non-modulated regions Ba and grating patterns Ga between the positive side of the axis Ax in the Y direction and the negative side in the Y direction (by making the non-modulated regions Ba relatively narrower on the negative side in the Y direction).

[0070] The modulation pattern PG4, like the modulation pattern PG2, includes a grating pattern Ga in a part of the region on the negative side of the axis Ax in the Y direction. In the modulation pattern PG4, the region in which the grating pattern Ga is provided is also a part in the X direction. That is, the modulation pattern PG4 includes a non-modulated region Ba, a grating pattern Ga, and a non-modulated region Ba arranged in order in the X direction in the region on the negative side of the axis Ax in the Y direction. Here, the grating pattern Ga is arranged in a region including an axis Ay along the Y direction passing through the center Lc of the beam spot of the laser light L in the X direction.

[0071] Any of the above modulation patterns PG2 to PG4 can make the beam shape of the focused spot C an inclined shape from the second region R2 to the first region R1 as it moves from the first surface 11a to the second surface 11b at least on the first surface 11a side of the center Ca. That is, in order to control the beam shape of the focused spot C to move from the second region R2 to the first region R1 as it moves from the first surface 11a to the second surface 11b at least on the first surface 11a side of the center Ca, an asymmetric modulation pattern such as the modulation patterns PG1 to PG4 or including the grating pattern Ga can be used, not limited to the modulation patterns PG1 to PG4. Then, by exchanging the positions of the grating pattern Ga and the non-modulation region Ba, an inclined shape in the opposite direction can be formed.

[0072] Furthermore, the asymmetric modulation pattern for making the beam shape of the focused spot C into an inclined shape is not limited to one that uses a grating pattern Ga. Fig. 17 is a diagram showing another example of an asymmetric modulation pattern. As shown in Fig. 17(a), the modulation pattern PE includes an elliptical pattern Ew on the negative side of the axis Ax in the Y direction, and includes an elliptical pattern Es on the positive side of the axis Ax in the Y direction. Note that Fig. 17(b) is obtained by inverting the modulation pattern PE in Fig. 17(a) so as to correspond to the entrance pupil surface 33a of the focusing lens 33.

[0073] As shown in FIG. 17(c), both of the elliptical patterns Ew and Es are patterns for making the beam shape of the focused spot C on the XY plane including the X and Y directions into an elliptical shape with the X direction as the longitudinal direction. However, the elliptical patterns Ew and Es have different modulation intensities. More specifically, the modulation intensity by the elliptical pattern Es is made larger than the modulation intensity by the elliptical pattern Ew. That is, the focused spot Cs formed by the laser light L modulated by the elliptical pattern Es is made to have an elliptical shape longer in the X direction than the focused spot Cw formed by the laser light L modulated by the elliptical pattern Ew. Here, a relatively strong elliptical pattern Es is arranged on the negative side of the Y direction from the axis Ax.

[0074] 18(a), by using such a modulation pattern PE, the beam shape of the focused spot C in the YZ plane can be made to be an inclined shape that is inclined to the negative side of the Y direction with respect to the Z direction on the first surface 11a side from the center Ca, that is, an inclined shape from the second region R2 to the first region R1 as it moves from the first surface 11a to the second surface 11b. Particularly in this case, the beam shape of the focused spot C in the YZ plane is inclined to the negative side of the Y direction with respect to the Z direction even on the side opposite to the first surface 11a from the center Ca, that is, an inclined shape from the first region R1 to the second region R2 as it moves from the first surface 11a to the second surface 11b, and becomes an arc shape overall.

[0075] In addition, in the modulation pattern PE, it is also possible to form a tilted shape in the opposite direction by interchanging the elliptical pattern Ew and the elliptical pattern Es. Also, each diagram in Fig. 18(b) shows the intensity distribution in the XY plane of the laser light L at each position H1 to F8 in the Z direction shown in Fig. 18(a), which is an actual observation result by a camera.

[0076] Furthermore, the modulation pattern for making the beam shape of the focused spot C into an inclined shape is not limited to the asymmetric pattern described above. As an example of such a modulation pattern, as shown in FIG. 19, a pattern for modulating the laser light L so as to form focused points CI at multiple positions in the YZ plane E and form a focused spot C having an inclined shape (including the multiple focused points CI) as a whole of the multiple focused points CI can be given. As an example, such a modulation pattern can be formed based on an axicon lens pattern. When such a modulation pattern is used, the modified region 12 itself can also be formed obliquely in the YZ plane.

[0077] In addition, when controlling the beam shape, if the offset of the spherical aberration correction pattern is used, if the coma aberration pattern is used, or if the elliptical pattern is used, processing with high energy is possible compared to when a diffraction grating pattern is used to cut off part of the laser light. Furthermore, these cases are effective when emphasis is placed on the formation of cracks. Furthermore, when the coma aberration pattern is used, it is possible to make only the beam shape of some of the focused spots an inclined shape in the case of multi-focus processing. Furthermore, when the axicon lens pattern is used, it is effective when emphasis is placed on the formation of modified regions compared to other patterns.

[0078] Next, a modified example of the processing object will be described. FIG. 20 is a diagram showing an object according to the modified example. FIG. 20(a) is a plan view, and FIG. 20(b) is a cross-sectional view taken along the line XXb-XXb in FIG. 20(a). In this example, one large-area semiconductor device 11E (e.g., a Si photodiode) is formed on one object 11, and a line A is set along the outer edge of the semiconductor device 11E so as to surround the semiconductor device 11E. Therefore, the second region R2 including the semiconductor device 11E faces the first region R1 in which the semiconductor device 11E is not formed, via the street region Rs in which the line A is set. In this case, the second region R2 is an active region, and the first region R1 is an inactive region different from the active region. The active region is a region including a functional element such as the semiconductor device 11E. The inactive region is a region that does not include a functional element such as the semiconductor device 11E, or a region that includes an element having a certain function, but the element is a test element such as a TEG.

[0079] Therefore, even in this case, the first region R1 and the second region on the line A side have different structures. In this case, it is preferable to distribute the damage Dt caused by the light leakage Lt unevenly on the first region R1 side, not on the second region R2 including the semiconductor device 11E. Therefore, even in this case, as in the above embodiment, at least in step S101 and the first irradiation process, the control unit 6 modulates the laser light L using the spatial light modulator 7, so that the beam shape of the focused spot C1 in the YZ plane is inclined with respect to the Z direction at least on the first surface 11a side of the center Ca of the focused spot C1.

[0080] More specifically, in the step S101 and the first irradiation process, the control unit 6 controls the modulation pattern displayed by the spatial light modulator 7 so that the beam shape of the focused spot C1 in the YZ plane is an inclined shape from the second region R2 to the first region R1 as it moves from the first surface 11a to the second surface 11b at least on the first surface 11a side of the center Ca of the focused spot C1. As a result, the damage Dt caused by the leaking light Lt is unevenly distributed in the first region R1 where the semiconductor device 11E does not exist, and the influence of the damage Dt caused by the leaking light Lt is reduced. Note that in the object 11 of this example, a TEG sensor 11G for characteristic confirmation may be formed around the semiconductor device 11E. In this case, the line A may be set to pass partially between the semiconductor device 11E and the TEG sensor 11G. In this case, the beam shape of the focused spot C1 may also be inclined so that the damage Dt of the leaking light Lt is unevenly distributed on the opposite side to the semiconductor device 11E.

[0081] FIG. 21 is a diagram showing an object according to another modified example. FIG. 21(a) is a plan view, and FIG. 21(b) is a cross-sectional view along line XXIb-XXIb in FIG. 21(a). In this example, a plurality of semiconductor devices 11D are two-dimensionally arranged along the second surface 11b of the object 11, as in the above embodiment, but the interval between adjacent semiconductor devices 11D is wide. For this reason, in this example, two lines A are set in the region between adjacent semiconductor devices 11D (W line processing is performed). Each line A is set biased toward one semiconductor device 11D side from the center of the region between adjacent semiconductor devices 11D.

[0082] Therefore, in this example, a pair of street regions Rs in which a pair of lines A are respectively set are interposed between a pair of second regions R2 including a pair of adjacent semiconductor devices 11D, and one first region R1 (a region in which the semiconductor devices 11D are not formed) is provided between the pair of street regions Rs. Therefore, in this case as well, when focusing on one line A, the structures of parts of the first region R1 and the second region R2 on the line A side are different. In this case as well, the second region R2 is an active region, and the first region R1 is an inactive region different from the active region. And, in this example, when processing any line A, it is desirable to unevenly distribute the damage Dt of the through light Lt on the first region R11 side in which the semiconductor devices 11D are not formed.

[0083] Therefore, in the step S101 and the first irradiation process, when processing the line A on the negative side in the Y direction of the pair of lines A (that is, when the second region R2 is located on the negative side in the Y direction as viewed from the processing progress direction FD (X direction)), the control unit 6 forms the focused spot C11 as shown in FIG. 22. The focused spot C11 is inclined from the second region R2 to the first region R1 on the first surface 11a side from the center Ca as it moves from the first surface 11a to the second surface 11b (as it moves toward the negative side in the Z direction). Note that the focused spot C11 is inclined from the first region R1 to the second region R2 on the second surface 11b side from the center Ca as it moves from the first surface 11a to the second surface 11b (as it moves toward the negative side in the Z direction). As a result, the beam shape of the focused spot C11 in the YZ plane is an arc shape that is convex on the positive side in the Y direction as a whole.

[0084] On the other hand, in the step S101 and the first irradiation process, when processing the line A on the positive side in the Y direction of the pair of lines A (that is, when the second region R2 is located on the positive side in the Y direction as viewed from the processing progress direction FD (X direction)), the control unit 6 forms the focused spot C12 as shown in FIG. 23. The focused spot C12 is inclined from the second region R2 to the first region R1 on the first surface 11a side from the center Ca as it moves from the first surface 11a to the second surface 11b (as it moves toward the negative side in the Z direction). Note that the focused spot C12 is inclined from the first region R1 to the second region R2 on the second surface 11b side from the center Ca as it moves from the first surface 11a to the second surface 11b (as it moves toward the negative side in the Z direction). As a result, the beam shape of the focused spot C12 in the YZ plane is an arc shape that is convex on the negative side in the Y direction as a whole. When forming the focused spots C11 and C12, for example, coma aberration can be utilized.

[0085] As a result, as shown in Fig. 24, in the processing of either of the pair of lines A, the damage Dt of the light leakage Lt is concentrated on the first region R1 side where the semiconductor device 11D is not formed, so that the influence of the damage Dt of the light leakage Lt on the second region R2 side including the semiconductor device 11D can be reduced. Note that, as shown in Fig. 24(b), in the target 11 according to this modification, a structure 11F such as a test chip or a TEG may be formed between adjacent semiconductor devices 11D. In such a case, when the processing proceeding direction FD is at least a direction intersecting the direction in which the structure 11F is interposed between the adjacent semiconductor devices 11D (here, the Y direction), two lines A are set to straddle the structure 11F, and W line processing is performed.

[0086] In this case, similarly to the above example, the region including the structure 11F is defined as the first region R1, and the beam shapes of the focused spots C11 and C12 are controlled so that the damage Dt due to the leakage light Lt is unevenly distributed on the first region R1 side. On the other hand, when the direction intersecting the direction in which the structure 11F is not interposed between the adjacent semiconductor devices 11D (here, the X direction) is defined as the processing proceeding direction FD, the interval between the adjacent semiconductor devices 11D may be narrowed, and processing may be performed along one line A. In this case, the structures of the adjacent semiconductor devices 11D are compared in this direction, and the beam shape of the focused spot C1 is controlled so that the damage Dt due to the leakage light Lt is unevenly distributed on the side opposite to the side having a structure relatively vulnerable to the leakage light Lt.

[0087] FIG. 25 is a diagram showing an object according to yet another modified example. FIG. 25(a) is a plan view, and FIG. 25(b) is a cross-sectional view taken along line XXVb-XXVb in FIG. 25(a). In this example, a line A is set in an annular shape in the object 11 when viewed from the Z direction. The object 11 is also bonded to another wafer 11Z via a device layer 11Q. A trimming process is performed on this object 11. In the trimming process, a laser beam L is irradiated along the line A to form a plurality of rows of modified regions 12a and 12b aligned in the Z direction, a crack (diagonal crack 13a) extending from the modified region 12a, and a crack (vertical crack 13b) extending from the modified region 12b. This removes the annular region outside the line A from the object 11.

[0088] When forming the modified region 12a, step S101 and a first irradiation process are performed. That is, first, the laser light L is incident on the object 11 from the first surface 11a side so that a focused spot C1 of the laser light L is formed at a first Z position in the Z direction inside the object 11 (see FIG. 26). The first Z position is a position closer to the second surface 11b than the first surface 11a, and is a position where the modified region 12a closest to the second surface 11b is formed. In this state, the laser light L is irradiated onto the object 11 while the focused spot C1 of the laser light L is relatively moved along the line A.

[0089] At this time, the control unit 6 controls the modulation pattern to be displayed on the spatial light modulator 7 so that the beam shape of the focused spot C1 in the YZ plane including the Y and Z directions intersecting the line A and the Z direction becomes an inclined shape inclined with respect to the Z direction at least on the first surface 11a side from the center Ca of the focused spot C1. More specifically, in step S101 and the first irradiation process, the control unit 6 controls the modulation pattern to be displayed on the spatial light modulator 7 so that the beam shape of the focused spot C1 in the YZ plane becomes an inclined shape from the second region R2 toward the first region R1 as it moves from the first surface 11a to the second surface 11b at least on the first surface 11a side from the center Ca of the focused spot C1.

[0090] Here, the second region R2 includes an active area inside the device layer 11Q. The first region R1 is a region where the device layer 11Q is not formed (a region outside the device layer 11Q). That is, here again, the second region R2 is an active region, and the first region R1 is an inactive region different from the active region. The active region here is a region inside the device layer 11Q. The inactive region here is a region outside the device layer 11Q. Between the first region R1 and the second region R2, a third region R3 including an inactive area on the outer edge of the device layer 11Q is interposed. At least the line A for forming the modified region 12a is located in this third region R3 when viewed from the Z direction. Therefore, in this example, the structures of the parts of the first region R1 and the second region R2 on the line A side are different. In this example, the damage Dt due to the escape light Lt is concentrated on the first region R1 side opposite to the second region R2 which is the active area of ​​the device layer 11Q.

[0091] Subsequently, in the trimming process, step S102 and the second irradiation process are performed. That is, as shown in FIG. 26, the laser light L is incident on the object 11 from the first surface 11a side, and the focused spot C2 of the laser light L is formed at the second Z position in the Z direction inside the object 11. The second Z position is a position on the first surface 11a side by the shift amount Sz from the first Z position, and is a position for forming the modified region 12b located closest to the modified region 12a. Furthermore, here, the focused spot C2 is set to the second Y position shifted by the shift amount Sy in the Y direction from the first Y position, which is the position of the focused spot C1 in the Y direction.

[0092] Further, in this case, in step S102 and the second irradiation process, the laser light L2 is shaped so that the beam shape of the focused spot C2 is an inclined shape that is inclined in the shift direction (here, the negative side in the Y direction) at least on the first surface 11a side from the center of the focused spot C2. As an example, the beam shape of the focused spot C2 can be the same as that of the focused spot C1. As a result, the oblique crack 13a is formed so as to be inclined in the shift direction of the focused spot C2 in the YZ plane. The oblique crack 13a is formed so as to be inclined toward the outside of the object 11 as it moves from the first surface 11a to the second surface 11b. As a result, it is possible to prevent the crack from extending vertically from the modified region 12 to the second surface 11b side and reaching the device layer 11Q or another wafer 11Z.

[0093] In addition, when forming modified region 12b other than modified region 12b closest to modified region 12a, the beam shape of focused spot C2 can be made non-inclined along the Z direction so that a vertical crack 13b extending along the Z direction is formed.

[0094] As described above, in the trimming process of the object 11, by controlling the beam shape of the focused spot C1 in step S101 and the first irradiation process, it is possible to reduce the effect of damage Dt from the escape light Lt, and also to prevent the formation of an oblique crack 13a toward the second surface 11b, thereby preventing the crack from unintentionally propagating into the device layer 11Q or another wafer 11Z.

[0095] In the above example, the formation of the oblique crack 13a during trimming and the reduction of the effect of the damage Dt of the leakage light Lt are used in combination. However, there is a demand for forming the oblique crack 13a even in processes other than trimming. Therefore, in any case where the oblique crack 13a is formed, the beam shape of the focused spot C1 can be controlled to reduce the effect of the damage Dt of the leakage light Lt. [Explanation of symbols]

[0096] 1...laser processing apparatus, 2...stage (support part), 4, 5...drive part (moving part), 6...control part, 7...spatial light modulator, 11...object, 11a...first surface, 11b...second surface, 31...light source, 33...collecting lens, A...line, C, C1, C2...collecting spot, R1...first region, R2...second region, W...wiring part.

Claims

1. A support portion that supports an object; A light source that outputs laser light; a spatial light modulator for modulating the laser light output from the light source in accordance with a modulation pattern and outputting the modulated laser light; a focusing lens for focusing the laser light output from the spatial light modulator toward the object and forming a focused spot of the laser light on the object; a moving unit for moving the focused spot relative to the object; A control unit that controls at least the light source, the spatial light modulator, and the moving unit; Equipped with the target object includes a first surface that is an incident surface of the laser light, a second surface opposite to the first surface, and a first region and a second region that are arranged on the second surface, and a line that moves the focused spot relatively is set so as to pass between the first region and the second region; At least a portion of the first region and the second region on the line side have different structures from each other, the control unit controls the light source, the spatial light modulator, and the moving unit to execute a first irradiation process in which the laser light is irradiated onto the object while relatively moving the focused spot along the line in a state in which the focused spot is positioned at a first Z position that is closer to the second surface than the first surface in a Z direction intersecting the first surface and the second surface; The line is set to have a circular shape when viewed from the Z direction, In the first irradiation process, the control unit controls the modulation pattern to be displayed on the spatial light modulator so that the beam shape of the focused spot in a YZ plane including the line and the Y and Z directions intersecting with the Z direction has an inclined shape that is inclined with respect to the Z direction toward the outside of the object from the first surface toward the second surface at least on the first surface side of the center of the focused spot. Laser processing equipment.

2. the object is bonded to another wafer via a device layer including the second region; 2. The laser processing apparatus according to claim 1.

3. the control unit controls the light source, the spatial light modulator, and the moving unit to perform a second irradiation process in which the laser light is irradiated onto the object while relatively moving the focused spot along the line in a state in which the focused spot is positioned at a second Z position that is farther away from the second surface in the Z direction than the first Z position; In the second irradiation process, the control unit controls the spatial light modulator to control the modulation pattern to be displayed by the spatial light modulator so that the beam shape of the focused spot in the YZ plane becomes an inclined shape that is inclined with respect to the Z direction so as to move outward from the first surface toward the second surface at least on the first surface side of the center of the focused spot.

3. The laser processing apparatus according to claim 1 or 2.

4. the control unit controls the light source, the spatial light modulator, and the moving unit to perform a second irradiation process in which the laser light is irradiated onto the object while relatively moving the focused spot along the line in a state in which the focused spot is positioned at a second Z position that is farther away from the second surface in the Z direction than the first Z position; In the second irradiation process, the control unit controls the spatial light modulator to make the beam shape of the focused spot in the YZ plane a non-inclined shape along the Z direction.

3. The laser processing apparatus according to claim 1 or 2.

5. A laser processing method for irradiating a laser beam onto an object including a first surface, a second surface opposite to the first surface, and a first region and a second region arranged along the second surface, the object having a line set so as to pass between the first region and the second region, a first irradiation step of irradiating the laser light to the object while relatively moving the focused spot along the line in a state where the focused spot of the laser light is positioned at a first Z position closer to the second surface side than the first surface in a Z direction intersecting the first surface and the second surface, At least a portion of the first region and the second region on the line side have different structures from each other, The line is set to have a circular shape when viewed from the Z direction, In the first irradiation step, the laser light is modulated so that a beam shape of the focused spot in a YZ plane including a Y direction and the Z direction intersecting the line and the Z direction has an inclined shape that is inclined with respect to the Z direction toward the outside of the object as it moves from the first surface to the second surface, at least on the first surface side of the center of the focused spot. Laser processing method.

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