JP7629926B2 - Laser processing device and laser processing method - Google Patents

Description

One aspect of the present disclosure relates to a laser processing apparatus and a laser processing method.

Patent document 1 describes a laser processing device that includes a holding mechanism that holds a workpiece and a laser irradiation mechanism that irradiates the workpiece held by the holding mechanism with laser light. In the laser processing device described in Patent document 1, a laser irradiation mechanism having a focusing lens is fixed to a base, and the holding mechanism moves the workpiece in a direction perpendicular to the optical axis of the focusing lens.

Patent No. 5456510 JP 2020-069530 A

For example, in the manufacturing process of semiconductor devices, a trimming process may be performed to remove the outer edge portion of a semiconductor wafer as an unnecessary portion. However, it has been found that when removing the outer edge portion from an object by relatively moving the focal point of laser light along a line that extends in a ring shape inside the outer edge of the object to form a modified region along the line, the quality of the trimmed surface of the object formed by removing the outer edge portion may be reduced in some places.

On the other hand, according to the inventor's findings, when a crack is extended from the modified region from the laser light incident surface of the object to the opposite surface during trimming, there is a demand for the crack to be extended obliquely so as to be inclined in the thickness direction, rather than extending vertically along the thickness direction of the object. This is to prevent the crack from extending along the thickness direction to another object (e.g., another wafer bonded to the wafer as the object) located directly below the object along the thickness direction when the crack is extended along the thickness direction. In other words, the inventor has gained new findings in the above technical field that there is a demand for making it possible to form an oblique crack while suppressing deterioration in the quality of the trim surface of the object from which the outer edge portion has been removed.

Therefore, one aspect of the present disclosure aims to provide a laser processing apparatus and a laser processing method that are capable of forming an oblique crack while suppressing deterioration in the quality of the trimmed surface of an object from which an outer edge portion has been removed.

The inventors have conducted intensive research to solve the above problems and have come to the following findings. That is, first, when the object is a wafer having a (100) plane as the main surface and a first crystal orientation perpendicular to one (110) plane and a second crystal orientation perpendicular to another (110) plane, the deterioration of the quality of the outer surface can be suppressed by forming the beam shape so that it is inclined with respect to the processing direction so as to approach one of the first and second crystal orientations that has a larger angle with the processing direction (the direction of relative movement of the focusing point) (for example, see Patent Document 2 above).

More specifically, when a crack extending from a modified region is pulled in, for example, a first crystal orientation, the beam is made elongated and its longitudinal direction is not oriented in the direction of processing progress, but is inclined so as to approach a second crystal orientation on the opposite side of the processing progress direction from the first crystal orientation side. This acts to cancel out the crack extension force due to the elongated beam shape against the crack extension force due to the crystal orientation (crystal axis), and it is believed that the crack will extend precisely along the processing progress direction.

Furthermore, if a crack extending from the modified region is pulled in, for example, the second crystal orientation, the beam is made elongated and its longitudinal direction is not oriented in the machining direction, but is inclined relative to the machining direction so as to approach the first crystal orientation on the opposite side to the second crystal orientation. This causes the crack extension force resulting from the elongated beam shape to counteract the crack extension force due to the crystal orientation, and it is believed that the crack will extend precisely along the machining direction BD. As a result, it is believed that deterioration in the quality of the trimmed surface is suppressed.

On the other hand, the inventor of the present invention, through further research based on the above findings, discovered that even when the longitudinal direction of the beam shape is set as described above based on the machining direction and the crystal structure, there is room for further suppression of deterioration in the quality of the trimmed surface, depending on the relationship between the longitudinal direction of the beam shape and the inclination direction of the diagonal crack. In other words, when the longitudinal direction of the beam shape and the inclination direction of the diagonal crack are on the same side of the machining direction, the quality of the trimmed surface is relatively good, whereas when the longitudinal direction of the beam shape and the inclination direction of the diagonal crack are on opposite sides of the machining direction, the quality of the trimmed surface may be relatively poor.

In particular, when the point where the line defining the processing direction intersects with the second crystal orientation at right angles is defined as 0°, the point where the line intersects with the first crystal orientation at right angles is defined as 90°, and the midpoint between 0° and 90° on the line is defined as 45°, if the longitudinal direction of the beam shape and the inclination direction of the diagonal crack are on opposite sides of the processing direction when processing the 45° point, the quality of the trimmed surface is likely to deteriorate. One aspect of the present disclosure has been made based on the above findings.

That is, a laser processing apparatus according to one aspect of the present disclosure is a laser processing apparatus for irradiating a target object with laser light to form a modified region, and includes a support section for supporting the target object, an irradiation section for irradiating the laser light toward the target object supported by the support section, a moving section for moving a focusing region of the laser light relative to the target object, and a control section for controlling the moving section and the irradiation section, and the target object has a crystal structure including a (100) plane, one (110) plane, another (110) plane, a first crystal orientation perpendicular to the one (110) plane, and a second crystal orientation perpendicular to the other (110) plane. The object is supported by the support unit so that the (100) plane is the incident surface of the laser light, and an annular line including an arc-shaped first region and an arc-shaped second region having a boundary between the first region is set on the object when viewed from the Z direction intersecting the incident surface, the irradiation unit has a shaping unit that shapes the laser light so that the light collecting region has a longitudinal direction when viewed from the Z direction, and the control unit controls the irradiation unit and the moving unit to relatively move the light collecting region along the first region of the line, thereby forming a modified region in the object along the first region, and also causes a laser beam to be emitted from the modified region in a direction opposite to the incident surface of the object. A first processing process is performed to form an oblique crack extending obliquely with respect to the Z direction toward the opposite surface on the opposite side, and a second processing process is performed to form a modified region in the object along the second region by relatively moving the light collecting region along the second region of the line by controlling the irradiation unit and the movement unit, and to form an oblique crack extending from the modified region toward the opposite surface. In the first processing process and the second processing process, the control unit controls the forming unit to move the light collecting region in such a way that the longitudinal direction of the light collecting region is aligned with one of the first crystal orientation and the second crystal orientation that has a larger angle with the processing progress direction, which is the movement direction of the light collecting region. By shaping the laser light so that it is inclined toward the processing direction and controlling the moving unit, the forward and reverse processing directions are made the same for the first processing process and the second processing process, the point where the second crystal orientation and the line intersect perpendicularly is set to 0°, the point where the first crystal orientation and the line intersect perpendicularly is set to 90°, and the midpoint on the line between 0° and 90° is set to 45°, and the boundary between the first and second regions is set so that one of the first and second regions, when viewed from the Z direction, includes a point of 45°, which is on the same side as the side along which the diagonal crack extends with respect to the processing direction.

Alternatively, a laser processing method according to one aspect of the present disclosure is a laser processing method for irradiating a target with laser light to form a modified region, comprising: a first processing step of relatively moving a focusing region of the laser light along a first region of a line set on the target, thereby forming a modified region in the target along the first region, and forming an oblique crack extending obliquely from the modified region to an opposite surface of the target opposite to the incident surface of the laser light, with respect to the Z direction, intersecting the incident surface; and a second processing step of relatively moving the focusing region along a second region of the line, thereby forming a modified region in the target along the second region, and forming an oblique crack extending from the modified region to the opposite surface, wherein the target has a crystal structure including a (100) plane, one (110) plane, another (110) plane, a first crystal orientation perpendicular to the one (110) plane, and a second crystal orientation perpendicular to the other (110) plane, and the (100) plane is the incident surface, and the target In the first machining step and the second machining step, a circular line including an arc-shaped first region and an arc-shaped second region having a boundary between the first region and the first region is set as viewed from the Z direction, and the laser light is shaped so that the light collecting region has a longitudinal direction as viewed from the Z direction and the longitudinal direction of the light collecting region is inclined with respect to the processing proceeding direction in a direction approaching one of the first crystal orientation and the second crystal orientation having a larger angle with the processing proceeding direction, which is the moving direction of the light collecting region. In addition, when the forward and reverse directions of the processing are the same in the first forming process and the second forming process, the point where the second crystal orientation and the line intersect perpendicularly is defined as 0°, the point where the first crystal orientation and the line intersect perpendicularly is defined as 90°, and the midpoint on the line between 0° and 90° is defined as 45°, the boundary between the first region and the second region is set so that one of the first region and the second region, when viewed from the Z direction, includes a point of 45° on the same side as the side along which the diagonal crack extends relative to the processing direction.

In these devices and methods, the object has a crystal structure including a (100) plane, one (110) plane, another (110) plane, a first crystal orientation perpendicular to the one (110) plane, and a second crystal orientation perpendicular to the other (110) plane. Here, in the case where a modified region is formed in the object along a first region of the line that moves the focusing region of the laser light relatively (first processing process, first processing step), and in the case where a modified region is formed in the object along a second region of the line (second processing process, second processing step), the laser light is shaped so that the longitudinal direction of the focusing region is inclined with respect to the processing direction in a direction approaching one of the first crystal orientation and the second crystal orientation that has a larger angle with the processing direction. Therefore, as shown in the above findings, deterioration of the quality of the trimmed surface is suppressed.

On the other hand, in these devices and methods, in the first processing process and the second processing process (the same applies to the first processing step and the second processing step (hereinafter the same)), a diagonal crack is formed that extends obliquely in the Z direction (the direction intersecting the incident surface) from the modified area toward the opposite surface of the object opposite the incident surface. Therefore, as shown in the above findings, it is necessary to consider the relationship between the extension direction of this diagonal crack and the longitudinal direction of the focusing area. In particular, when processing a 45° point, if the longitudinal direction of the focusing area and the inclination direction of the diagonal crack are opposite each other with respect to the processing progress direction, a deterioration in the quality of the trimmed surface is likely to occur.

In contrast, in these devices and methods, the boundary between the first and second regions is set so that one of the first and second regions, in which the direction of the longitudinal inclination is the same as the side along which the oblique crack extends relative to the machining direction, includes a 45° point. In other words, the first and second regions, in which machining is performed with the longitudinal direction of the light collection region and the inclination direction of the oblique crack on opposite sides of the machining direction, do not reach the 45° point on the line. Therefore, quality degradation is suppressed. In this way, these devices and methods make it possible to form an oblique crack while suppressing quality degradation of the trim surface of the object.

Furthermore, in these devices and methods, the forward and reverse processing directions are the same for the first processing process and the second processing process. Therefore, compared to switching the forward and reverse processing directions between the first processing process and the second processing process, the time required for accelerating and decelerating the relative movement of the focused area of the laser light is reduced.

In the laser processing device according to one aspect of the present disclosure, one of the first region and the second region may be longer than the other of the first region and the second region. In this manner, the lengths of the first region and the second region may be set to be different.

In a laser processing apparatus according to one aspect of the present disclosure, the object includes a first portion and a second portion arranged in sequence from the opposite side along the Z direction, and the control unit performs a first processing process and a second processing process on the first portion while keeping the forward and reverse directions of the processing progress the same, and performs a separate processing process different from the first processing process and the second processing process on the second portion, and in the separate processing process, the control unit controls the irradiation unit and the moving unit to relatively move the focusing area along the line while keeping the forward and reverse directions of the processing progress the same throughout the entire line, thereby forming a modified area in the object along the line and a crack extending from the modified area along the Z direction. In this case, in the second portion where the crack is formed along the Z direction, the laser processing is performed with the direction of the processing progress the same throughout the entire line. Therefore, the time required for accelerating and decelerating the relative movement of the focusing area of the laser light is reduced compared to the case where the forward and reverse directions of the processing progress are switched between the first and second areas of the line in the second portion.

In the laser processing apparatus according to one aspect of the present disclosure, in the separate processing step, the control unit may control the shaping unit to shape the laser light so that the longitudinal direction of the focused area is aligned with the processing progress direction. In this case, in the second portion that forms a crack along the Z direction, there is no need to shape the laser light so as to change the relationship between the longitudinal direction of the focused area and the processing progress direction between the processing of the first area and the processing of the second area of the line, and therefore the processing of the control unit is simplified.

In a laser processing apparatus according to one aspect of the present disclosure, the object includes a joining region joined to another member, and in the first processing process and the second processing process, the control unit may form an oblique crack that is inclined from an inner position of the joining region toward the outer edge of the joining region as it moves from the incident surface toward the opposite surface. In this case, when a part of the object is removed from the object with the oblique crack as a boundary and the remaining part of the object is left, it is possible to prevent the remaining part of the object from extending outward beyond the joining region with the other member of the object.

In a laser processing apparatus according to one aspect of the present disclosure, in the first processing process and the second processing process, the control unit performs a first formation process in which a first modified region and a crack extending from the first modified region are formed in the target object as a modified region by setting the position of the light collection region in the Z direction to a first Z position and relatively moving the light collection region along the line, and a second formation process in which a second modified region and a crack extending from the second modified region are formed in the target object as a modified region by setting the position of the light collection region in the Z direction to a second Z position that is closer to the incident surface than the first Z position and relatively moving the light collection region along the line. In the first forming process, the control unit sets the position of the light collection area in the Y direction intersecting the processing progress direction and the Z direction to a first Y position, and in the second forming process, the control unit sets the position of the light collection area in the Y direction to a second Y position shifted from the first Y position, and by controlling the shaping unit, the laser light is shaped so that the shape of the light collection area in the YZ plane including the Y direction and the Z direction is an inclined shape that is inclined in the shift direction at least on the incident surface side from the center of the light collection area, thereby forming an oblique crack inclined in the shift direction in the YZ plane. In this way, it is possible to preferably form an oblique crack inclined with respect to the Z direction.

In a laser processing apparatus according to one aspect of the present disclosure, the shaping unit includes a spatial light modulator for shaping the laser light by modulating the laser light according to a modulation pattern, the irradiation unit includes a focusing lens for focusing the laser light from the spatial light modulator toward the target object, and in the second forming process, the control unit may shape the laser light by modulating the laser light so that the shape of the focused region becomes an inclined shape by controlling the modulation pattern displayed on the spatial light modulator. In this case, the laser light can be easily shaped using the spatial light modulator.

In the laser processing apparatus according to one aspect of the present disclosure, the modulation pattern includes a coma aberration pattern for imparting coma aberration to the laser light, and in the second formation process, the control unit may perform a first pattern control for making the shape of the light-collecting region an inclined shape by controlling the magnitude of the coma aberration due to the coma aberration pattern. According to the knowledge of the present inventor, in this case, the shape of the light-collecting region in the YZ plane is formed in an arc shape. That is, in this case, the shape of the light-collecting region is inclined in the shift direction on the incident surface side from the center of the light-collecting region, and is inclined in the opposite direction to the shift direction on the opposite side of the incident surface from the center of the light-collecting region. Even in this case, it is possible to form an oblique crack inclined in the shift direction.

In the laser processing device according to one aspect of the present disclosure, the modulation pattern includes a spherical aberration correction pattern for correcting the spherical aberration of the laser light, and in the second formation process, the control unit may perform second pattern control for making the shape of the light-collecting region an inclined shape by offsetting the center of the spherical aberration correction pattern in the Y direction with respect to the center of the entrance pupil plane of the focusing lens. According to the knowledge of the present inventor, in this case as well, the shape of the light-collecting region in the YZ plane can be formed into an arc shape, as in the case of using a coma aberration pattern, and an oblique crack inclined in the shift direction can be formed.

In the laser processing apparatus according to one aspect of the present disclosure, in the second formation process, the control unit may perform a third pattern control for making the shape of the light-collecting region an inclined shape by causing the spatial light modulator to display a modulation pattern that is asymmetric with respect to an axis along the processing progress direction. According to the knowledge of the present inventor, in this case, the entire shape of the light-collecting region in the YZ plane can be inclined in the shift direction. Even in this case, it is possible to form an oblique crack that is inclined in the shift direction.

In a laser processing device according to one aspect of the present disclosure, the modulation pattern includes an elliptical pattern for forming an elliptical shape with the X direction as the long axis in the X direction in the shape of the focused area in an XY plane including the X direction and the Y direction intersecting the Y direction and the Z direction, and in the second forming process, the control unit may perform a fourth pattern control for forming an inclined shape in the shape of the focused area by displaying the modulation pattern on the spatial light modulator so that the intensity of the elliptical pattern is asymmetric with respect to an axis line along the X direction. According to the knowledge of the inventor, even in this case, the shape of the focused area in the YZ plane can be formed into an arc shape, and an oblique crack inclined in the shift direction can be formed.

In the laser processing apparatus according to one aspect of the present disclosure, in the second formation process, the control unit may perform a fifth pattern control for making the shape of the light-focusing region including the multiple light-focusing points into an inclined shape by displaying a modulation pattern for forming multiple laser light focus points arranged along the shift direction in the YZ plane on the spatial light modulator. According to the knowledge of the present inventor, even in this case, it is possible to form an oblique crack inclined in the shift direction.

According to one aspect of the present disclosure, a laser processing apparatus and a laser processing method can be provided that are capable of forming an oblique crack while suppressing deterioration in the quality of the trimmed surface of an object from which an outer edge portion has been removed.

FIG. 1 is a schematic diagram showing a configuration of a laser processing apparatus according to an embodiment. FIG. 2 is a schematic diagram showing the configuration of the laser irradiation unit shown in FIG. FIG. 3 is a diagram showing the 4f lens unit shown in FIG. FIG. 4 is a diagram showing the spatial light modulator shown in FIG. FIG. 5 is a cross-sectional view of an object for explaining the knowledge of oblique crack formation. FIG. 6 is a cross-sectional view of an object for explaining the knowledge of oblique crack formation. FIG. 7 is a diagram showing the beam shape of the focused region of the laser light. FIG. 8 is a diagram showing the offset of the modulation pattern. FIG. 9 is a cross-sectional photograph showing the state of formation of the diagonal crack. FIG. 10 is a schematic plan view of the object. FIG. 11 is a cross-sectional photograph showing the state of formation of the diagonal crack. FIG. 12 is a cross-sectional photograph showing the state of formation of the diagonal crack. FIG. 13 is a diagram showing an example of a modulation pattern. FIG. 14 is a diagram showing the intensity distribution on the entrance pupil plane of the condenser lens and the beam shape in the condensed region. FIG. 15 is a diagram showing the beam shape in the focused region and the observation results of the intensity distribution in the focused region. FIG. 16 is a diagram showing an example of a modulation pattern. FIG. 17 is a diagram showing another example of an asymmetric modulation pattern. FIG. 18 is a diagram showing the intensity distribution on the entrance pupil plane of the condenser lens and the beam shape in the condensed region. FIG. 19 is a diagram showing an example of a modulation pattern and the formation of a light collecting region. FIG. 20 is a diagram showing an object to be processed. FIG. 21 is a diagram showing an object to be processed. FIG. 22 is a schematic diagram showing the beam shape in the focused region. FIG. 23 is a schematic diagram showing the beam shape in the focused region. FIG. 24 is a diagram showing one step of the trimming process. FIG. 25 is a diagram showing one step of the trimming process. FIG. 26 is a diagram showing one step of the trimming process. FIG. 27 is a diagram showing one step of the trimming process. FIG. 28 is a diagram showing one step of the trimming process. FIG. 29 is a diagram showing one step of the trimming process. FIG. 30 is a diagram showing an object to be laser processed according to one embodiment. FIG. 31 is a cross-sectional view of the object shown in FIG. FIG. 32 is a plan view of the object shown in FIG. FIG. 33 is a cross-sectional photograph showing the processing result. FIG. 34 is a cross-sectional photograph showing the processing result. FIG. 35 is a schematic diagram for explaining the processing test. FIG. 36 is a schematic diagram showing the relationship between the machining direction, the beam shape, and the oblique cracks in the machining test. FIG. 37 is a table showing the results of the machining tests shown in FIGS. FIG. 38 is a table showing the results of the processing test. FIG. 39 is a cross-sectional photograph showing the results of the processing test. FIG. 40 is a diagram showing one step of laser processing according to one embodiment. FIG. 41 is a diagram showing a step of laser processing according to one embodiment. FIG. 42 is a diagram showing one step of laser processing according to one embodiment. FIG. 43 is a diagram showing one step of laser processing according to one embodiment. FIG. 44 is a diagram showing a step of laser processing according to one embodiment. FIG. 45 is a diagram showing a step of laser processing according to one embodiment. FIG. 46 is a diagram showing a step of laser processing according to one embodiment. FIG. 47 is a diagram showing a step of laser processing according to one embodiment. FIG. 48 is a diagram showing an object to be laser processed according to one embodiment. FIG. 49 is a table showing the results of the processing test. FIG. 50 is a table showing the results of the processing test.

An embodiment will be described in detail below with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and 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.
[Outline of laser processing device and laser processing]

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

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.

The 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 the focused area C (e.g., the center Ca described below) of the laser light L, and a modified area 12 is formed inside the object 11. The focused area C, which will be described in detail later, is a position where the beam intensity of the laser light L is highest or an area within a predetermined range from the center of gravity of the beam intensity.

The modified region 12 is a region whose density, refractive index, mechanical strength, and other physical properties are different from those of the surrounding unmodified region. Examples of the modified region 12 include a melting treatment region, a crack region, an insulation 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.

As an example, when the stage 2 is moved along the X direction and the focusing area C is moved along the X direction relative to the object 11, multiple modified spots 12s are formed lined up in a row along the X direction. One modified spot 12s is formed by irradiating one pulse of laser light L. A row of modified areas 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 focusing area C with respect to the object 11 and the repetition frequency of the laser light L.

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

The control unit 6 controls the operation of the stage 2, the irradiation unit 3, and the movement units 4 and 5. The control unit 6 has a processing unit, a memory unit, and an input reception unit (not shown). The processing unit is configured as a computer device including a processor, memory, storage, and a communication device, etc. In the processing unit, the processor executes software (programs) loaded into the memory, etc., and controls the 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 types of data. The input reception unit is an interface unit that displays various types of information and receives input of various types of information from the user. The input reception unit constitutes a GUI (Graphical User Interface).

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

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 constitute 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, 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 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 the Fourier plane.

As shown in Fig. 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 stacking a drive circuit layer 72, a pixel electrode layer 73, a reflective film 74, an alignment film 75, a liquid crystal layer 76, an alignment film 77, a transparent conductive film 78, and a transparent substrate 79 in this order on a semiconductor substrate 71.

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

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, a rubbing treatment. The alignment films 75, 77 align the liquid crystal molecules 76a contained in the liquid crystal layer 76 in a certain direction.

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.

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

That is, when the laser light L is incident on the liquid crystal layer 76 from the outside through the transparent substrate 79 and the transparent conductive film 78 with the modulation pattern displayed on the liquid crystal layer 76, reflected by the reflective film 74, and 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.

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 condensed by the condenser lens 33 inside the object 11, thereby forming the modified region 12 and cracks extending from the modified region 12 in the object 11 in the condensed region C. Furthermore, the control unit 6 controls the moving units 4 and 5 to move the condensed region C relative to the object 11, thereby forming the modified region 12 and cracks along the movement direction of the condensed region C.
[Explanation of findings regarding oblique crack formation]

Here, the direction of relative movement of the focusing area C at this time (machining progress direction) is defined as the X direction. The direction intersecting (orthogonal) with the first surface 11a, which is the incident surface of the laser light L in the object 11, is defined as the Z direction. The direction intersecting (orthogonal) with the X direction and the Z direction is defined as the Y direction. The X direction and the Y direction are directions along the first surface 11a. The Z direction may be defined as the optical axis of the focusing lens 33, the optical axis of the laser light L focused toward the object 11 via the focusing lens 33.

As shown in Figure 5, there is a demand for forming a diagonal crack along a line RA inclined with respect to the Z and Y directions (here, a line RA inclined at a predetermined angle θ from the Y direction) in an intersecting plane (YZ plane S including the Y and Z directions) that intersects with the X direction, which is the processing progress direction. The inventor's findings regarding such diagonal crack formation will be explained with reference to a processing example.

Here, modified regions 12a and 12b are formed as modified region 12. As a result, crack 13a extending from modified region 12a and crack 13b extending from modified region 12b are connected to form crack 13 extending obliquely along line RA. Here, first, as shown in FIG. 6, a focusing region C1 is formed with the first surface 11a of object 11 as the incident surface of laser light L. On the other hand, a focusing region C2 is formed on the first surface 11a side of focusing region C1 with the first surface 11a as the incident surface of laser light L. At this time, focusing region C2 is shifted by distance Sz in the Z direction from focusing region C1, and shifted by distance Sy in the Y direction from focusing region C1. Distance Sz and distance Sy correspond to the inclination of line RA, as an example.

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

In this way, by shifting at least two light collection areas C1 and C2 in the Y direction and tilting the beam shape of at least the light collection area C2 (here, both light collection areas C1 and C2), it is possible to form a crack 13 extending obliquely, as shown in (a) of Fig. 9. Note that, for example, by controlling the modulation pattern of the spatial light modulator 7, the light collection areas C1 and C2 may be simultaneously formed by branching the laser light L to form the modified area 12 and the crack 13 (multi-focus processing), or after forming the modified area 12a and the crack 13a by forming the light collection area C1, the modified area 12b and the crack 13b may be formed by forming the light collection area C2 (single-pass processing).

In addition, by forming another light collection region between light collection region C1 and light collection region C2, as shown in (b) of Figure 9, another modified region 12c can be interposed between modified region 12a and modified region 12b, thereby forming a longer, diagonally extending crack 13.

Next, the knowledge for making the beam shape in the YZ plane S of the light collection area C into an inclined shape will be described. First, the definition of the light collection area C will be specifically described. Here, the light collection area C 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). As described above, 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. The position where the beam intensity is highest or the center of gravity of the beam intensity can be obtained as follows. That is, the laser light L is irradiated to the object 11 in a state where the output of the laser light L is lowered to a degree (lower than the processing threshold) such that the modified area 12 is not formed in 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 number 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.

In order to make the beam shape in the light-collecting region C an inclined shape, there is a method of offsetting the modulation pattern. More specifically, the spatial light modulator 7 displays various patterns such as a distortion correction pattern for correcting wavefront distortion, a grating pattern for branching the laser light, a slit pattern, an astigmatism pattern, a coma aberration pattern, and a spherical aberration correction pattern (a pattern in which these are superimposed is displayed). Of these, as shown in FIG. 8, the beam shape in the light-collecting region C can be adjusted by offsetting the spherical aberration correction pattern Ps.

8, in the modulation plane 7a, the center Pc of the spherical aberration correction pattern Ps is offset by an offset amount Oy1 to the negative side in the Y direction with respect to the center Lc (of the beam spot) of the laser light L. As described above, the modulation plane 7a is transferred to the entrance pupil plane 33a of the focusing lens 33 by the 4f lens unit 34. Therefore, the offset in the modulation plane 7a becomes an offset to the positive side in the Y direction on the entrance pupil plane 33a. That is, on the entrance pupil plane 33a, the center Pc of the spherical aberration correction pattern Ps is offset by an offset amount Oy2 to the positive side in the Y direction from the center Lc of the laser light L and the center of the entrance pupil plane 33a (here, coinciding with the center Lc).

In this way, by offsetting the spherical aberration correction pattern Ps, the beam shape of the focusing area C of the laser light L is deformed into an arc-shaped inclined shape as shown in FIG. 7. Offsetting the spherical aberration correction pattern Ps as described above is equivalent to imparting coma aberration to the laser light L. Therefore, the beam shape of the focusing area C may be made into an inclined shape by including a coma aberration pattern for imparting coma aberration to the laser light L in the modulation pattern of the spatial light modulator 7. Note that as the coma aberration pattern, a pattern equivalent to the ninth term of the Zernike polynomial (the Y component of the third-order coma aberration) and in which coma aberration occurs in the Y direction can be used.

Next, the findings regarding the relationship between the crystallinity of the object 11 and the crack 13 will be described. FIG. 10 is a schematic plan view of the object. Here, the object 11 is a silicon wafer (t 775 μm, <100>, 1 Ω·cm), and a notch 11d is formed. For this object 11, a first processing example in which the X direction, which is the processing progress direction, is aligned with the 0° (110) plane is shown in FIG. 11(a), a second processing example in which the X direction is aligned with 15° is shown in FIG. 11(b), another processing example in which it is aligned with 30° is shown in FIG. 12(a), and a fourth processing example in which it is aligned with the 45° (100) plane is shown in FIG. 12(b). In each processing example, the angle θ of the line RA from the Y direction in the YZ plane S is set to 71°.

In each processing example, the light collection area C1 is moved relatively in the X direction in the first pass to form the modified area 12a and the crack 13a, and then the light collection area C2 is moved relatively in the X direction in the second pass to form the modified area 12b and the crack 13b, in a single pass processing. The processing conditions for the first and second passes are as follows. Note that CP below indicates the strength of the light collection correction, and coma (LBA offset Y) indicates the offset amount of the spherical aberration correction pattern Ps in the Y direction in pixel units of the spatial light modulator 7.

<First pass>
Z direction position: 161μm
CP: -18
Output: 2W
Speed: 530 mm/s
Frequency: 80kHz
Frame (LBA offset Y): -5
Y direction position: 0

<Second pass>
Z direction position: 151μm
CP: -18
Output: 2W
Speed: 530 mm/s
Frequency: 80kHz
Frame (LBA offset Y): -5
Y direction position: 0.014mm

11 and 12, in either case, a crack 13 could be formed along a line RA inclined at 71° to the Y direction. That is, regardless of the influence of the (110) plane, (111) plane, and (100) plane, which are the main cleavage planes in the object 11, that is, regardless of the crystal structure of the object 11, a crack 13 extending obliquely along the desired line RA could be formed.

Note that the control of the beam shape for forming the crack 13 extending obliquely in this manner is not limited to the above example. Next, another example for making the beam shape 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, to make the beam shape of the focused area C 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 area 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 positive side of the axis Ax in the Y direction. Note that (b) of FIG. 13 is a modulation pattern PG1 in (a) of FIG. 13 inverted to correspond to the entrance pupil surface 33a of the focusing lens 33.

Figure 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 Figure 14 (a), by using such a modulation pattern PG1, the portion of the laser light L incident on the spatial light modulator 7 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 Figure 14 (b) and Figure 15, the beam shape of the focusing region C in the YZ plane S can be made into an inclined shape in which the entire beam shape is inclined in one direction with respect to the Z direction.

That is, in this case, the beam shape of the light collection area C is inclined toward the negative Y direction with respect to the Z direction on the first surface 11a side from the center Ca of the light collection area C, and is inclined toward the positive Y direction with respect to the Z direction on the opposite side of the first surface 11a from the center Ca of the light collection area C. Note that 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), and is the actual observation result by a camera. Even when the beam shape of the light collection area C is controlled in this way, a crack 13 extending obliquely can be formed, as in the above example.

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

The modulation pattern PG3 includes non-modulated regions Ba and grating patterns Ga arranged in sequence 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 away from the axis Ax on the positive side of the axis Ax in the Y direction. The modulation pattern PG3 is 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 of the Y direction (by making the non-modulated regions Ba relatively narrower on the negative side of the Y direction).

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

With any of the above modulation patterns PG2 to PG4, the beam shape of the light collection area C 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 at least on the first surface 11a side from the center Ca. In other words, in order to control the beam shape of the light collection area C to be inclined to the negative side of the Y direction with respect to the Z direction at least on the first surface 11a side from the center Ca, it is possible to use an asymmetric modulation pattern such as modulation patterns PG1 to PG4 or including a grating pattern Ga, not limited to modulation patterns PG1 to PG4.

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

As shown in FIG. 17(c), the elliptical patterns Ew and Es are both patterns for making the beam shape of the focusing area C in the XY plane including the X and Y directions an elliptical shape with the X direction as the longitudinal direction. However, the modulation strength is different between the elliptical patterns Ew and Es. More specifically, the modulation strength by the elliptical pattern Es is made greater than the modulation strength by the elliptical pattern Ew. That is, the focusing area 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 focusing area 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.

As shown in FIG. 18(a), by using such a modulation pattern PE, the beam shape of the focusing area C in the YZ plane S can be made to be an inclined shape that is inclined to the negative Y direction with respect to the Z direction on the first surface 11a side from the center Ca. In particular, in this case, the beam shape of the focusing area C in the YZ plane S is inclined to the negative Y direction with respect to the Z direction even on the side opposite the first surface 11a from the center Ca, and becomes an arc shape overall. Note that 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), and is the actual observation result by a camera.

Furthermore, the modulation pattern for making the beam shape of the focusing area C into an inclined shape is not limited to the above asymmetric pattern. As an example, as shown in FIG. 19, such a modulation pattern may be a pattern for modulating the laser light L so that the focusing points CI are formed at multiple positions in the YZ plane S to form the focusing area C having an inclined shape (including the multiple focusing points CI) as a whole of the multiple focusing points CI. 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 area 12 itself can also be formed obliquely in the YZ plane S. Therefore, in this case, an oblique crack 13 can be formed accurately according to the desired inclination. On the other hand, when such a modulation pattern is used, the length of the crack 13 tends to be shorter than the other examples described above. Therefore, by using various modulation patterns according to requirements, desired processing is possible.

The focal point CI is, for example, a point at which unmodulated laser light is focused. As described above, according to the inventor's findings, by shifting at least two modified regions 12a, 12b in the Y direction and the Z direction in the YZ plane S and by making the beam shape of the focal region C in the YZ plane S an inclined shape, it is possible to form a crack 13 that extends obliquely so as to be inclined in the Y direction with respect to the Z direction.

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 a part of the focusing area an inclined shape in the case of multi-focus processing. Furthermore, when the axicon lens pattern is used, the use of other patterns is effective compared to other patterns when emphasis is placed on the formation of a modified area.
[Example of trimming]

Next, an example of trimming will be described. Trimming is a process for removing unnecessary parts of the object 11. Trimming includes a laser processing method for forming a modified region 12 in the object 11 by irradiating the object 11 with laser light L by aligning the focusing region with the object 11. The object 11 includes, for example, a semiconductor wafer formed in a disk shape. The object is not particularly limited, and may be formed of various materials and may have various shapes. A functional element (not shown) is formed on the second surface 11b of the object 11. The functional element is, for example, a light receiving element such as a photodiode, a light emitting element such as a laser diode, a circuit element such as a memory, etc.

20 and 21 are diagrams showing an object to be processed. As shown in FIGS. 20 and 21, an effective area R and a removal area E are set in the object 11. The effective area R is a portion corresponding to the semiconductor device to be acquired. The effective area R here is a disk-shaped portion including the central portion when the object 11 is viewed from the thickness direction. The removal area E is a region outside the effective area R in the object 11. The removal area E is the outer edge portion of the object 11 other than the effective area R. The removal area E here is an annular portion surrounding the effective area R. The removal area E includes the peripheral portion (bevel portion of the outer edge) when the object 11 is viewed from the thickness direction. The effective area R and the removal area E can be set in the control unit 6. The effective area R and the removal area E may be specified by coordinates.

The stage 2 is a support on which the object 11 is placed. In this embodiment, the object 11 is placed on the stage 2 with the first surface 11a of the object 11 facing upward, which is the laser light incident surface side (with the second surface 11b facing downward, which is the stage 2 side). The stage 2 has a rotation axis Cx provided at its center. The rotation axis Cx is an axis that extends along the Z direction. The stage 2 is rotatable around the rotation axis Cx. The stage 2 is rotationally driven by the driving force of a known driving device such as a motor.

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

As described above, the irradiation unit 3 includes a spatial light modulator 7. The spatial light modulator 7 constitutes a shaping unit that shapes the shape of the focusing area C in a plane perpendicular to the optical axis of the laser light L (i.e., the shape of the focusing area C when viewed from the Z direction) (hereinafter also referred to as the "beam shape"). The spatial light modulator 7 can shape the laser light L so that the beam shape when viewed from the Z direction has a longitudinal direction. For example, the spatial light modulator 7 shapes the beam shape into an elliptical shape by displaying a modulation pattern that makes the beam shape an elliptical shape.

The beam shape is not limited to an ellipse, and may be an elongated shape. The beam shape may be a flattened circle, an ellipse, or a track shape. The beam shape may be an elongated triangle, a rectangle, or a polygon. The modulation pattern of the spatial light modulator 7 that realizes such a beam shape may include at least one of a slit pattern and an astigmatism pattern. In addition, when the laser light L has multiple focusing areas C due to astigmatism or the like, the shape of the focusing area C that is the most upstream in the optical path of the laser light L among the multiple focusing areas C is the beam shape of this embodiment (the same applies to other laser lights). The longitudinal direction here is the major axis direction of the ellipse shape related to the beam shape, and is also referred to as the major axis direction of the ellipse.

The beam shape is not limited to the shape of the focal point, but may be the shape near the focal point, and may be the shape of a part of the focal area C. For example, in the case of laser light L having astigmatism, as shown in FIG. 22(a), the beam shape has a longitudinal direction NH in the region on the laser light incident surface side near the focal point. In the beam intensity distribution within the plane of the beam shape in FIG. 22(a) (within the plane at the Z-direction position on the laser light incident surface side near the focal point), the distribution has a strong intensity in the longitudinal direction NH, and the direction of strong beam intensity coincides with the longitudinal direction NH.

In the case of laser light L having astigmatism, as shown in FIG. 22(c), in the region on the opposite side of the laser light incident surface near the focal point, the beam shape has a longitudinal direction NH0 perpendicular to the longitudinal direction NH of the region on the laser light incident surface side (see FIG. 22(a)). In the beam intensity distribution in the plane of the beam shape in FIG. 22(c) (in the plane at the Z-direction position on the opposite side of the laser light incident surface near the focal point), the distribution has a strong intensity in the longitudinal direction NH0, and the direction of strong beam intensity coincides with the longitudinal direction NH0. In the case of laser light L having astigmatism, as shown in FIG. 22(b), in the region between the laser light incident surface side and its opposite side near the focal point, the focal region C does not have a longitudinal direction and is circular.

In the case of laser light L having such astigmatism, the focusing region C targeted by this embodiment includes the region on the laser light incident surface side near the focusing point, and the beam shape targeted by this embodiment is the beam shape shown in (a) of Figure 22.

By adjusting the modulation pattern of the spatial light modulator 7, the position in the focusing region C where the beam shape shown in FIG. 22(a) is obtained can be controlled as desired. For example, the beam shape shown in FIG. 22(a) can be controlled in the region on the opposite side of the laser light incidence surface near the focusing point. Also, for example, the beam shape shown in FIG. 22(a) can be controlled in the region between the laser light incidence surface side and the opposite side near the focusing point. The position of the part of the focusing region C is not particularly limited, and may be any position between the laser light incidence surface of the object 11 and its opposite surface.

For example, when a slit or elliptical optical system using modulation pattern control and/or a mechanical mechanism is used, the beam shape has a longitudinal direction NH in the region on the laser light incidence surface side near the focal point, as shown in (a) of Figure 23. The beam intensity distribution in the plane of the beam shape in (a) of Figure 23 (in the plane at the Z-direction position on the laser light incidence surface side near the focal point) is a distribution with strong intensity in the longitudinal direction NH, and the direction of strong beam intensity coincides with the longitudinal direction NH.

When a slit or elliptical optical system is used, as shown in FIG. 23(c), in the region on the opposite side of the laser light incident surface near the focal point, the beam shape has the same longitudinal direction NH as the longitudinal direction NH of the region on the laser light incident surface side (see FIG. 22(a)). In the beam intensity distribution in the plane of the beam shape in FIG. 23(c) (in the plane at the Z-direction position on the opposite side of the laser light incident surface near the focal point), the distribution has a strong intensity in the longitudinal direction NH, and the direction of strong beam intensity coincides with the longitudinal direction NH. When a slit or elliptical optical system is used, as shown in FIG. 23(b), at the focal point, the beam shape has a longitudinal direction NH0 perpendicular to the longitudinal direction NH of the region on the laser light incident surface side (see FIG. 23(a)). In the beam intensity distribution within the plane of the beam shape in FIG. 23(b) (within the plane at the Z-direction position of the focal point), the distribution has a strong intensity in the longitudinal direction NH0, and the direction of strong beam intensity coincides with the longitudinal direction NH0.

When such a slit or elliptical optical system is used, the beam shape other than the focal point has a longitudinal direction, and the beam shape other than the focal point is the beam shape that is the subject of this embodiment. That is, a part of the focal region C that is the subject of this embodiment includes the region on the laser light incidence surface side near the focal point, and the beam shape that is the subject of this embodiment is the beam shape shown in (a) of FIG.

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

The control unit 6 rotates the stage 2 while positioning the focusing area C at a position along the line A (the periphery of the effective area R) on the object 11, and controls the start and stop of irradiation of the laser light L in the irradiation unit 3 based on the θ information, thereby performing peripheral processing to form a modified area along the periphery of the effective area R.

The control unit 6 performs a removal process to form a modified area in the removal area E by irradiating the laser light L onto the removal area E without rotating the stage 2 and moving the focus area C of the laser light L.

The control unit 6 controls at least one of the rotation of the stage 2, the irradiation of the laser light L from the irradiation unit 3, and the movement of the focusing area C so that the pitch (the distance between adjacent modification spots in the processing direction) of the multiple modification spots contained in the modification area is constant.

The control unit 6 acquires the reference position (position in the 0° direction) in the rotational direction of the object 11 and the diameter of the object 11 from an image captured by an alignment camera (not shown). The control unit 6 controls the movement of the irradiation unit 3 so that the irradiation unit 3 can move along the X direction to the rotation axis Cx of the stage 2.

Next, an example of trimming processing will be described. First, the object 11 is placed on the stage 2 so that the first surface 11a is the incident surface of the laser light L. The second surface 11b side of the object 11 on which the functional element is mounted is protected by a support substrate or tape material adhered thereto.

Next, trimming is performed. In trimming, the control unit 6 performs edge processing. Specifically, as shown in FIG. 24(a), while rotating the stage 2 at a constant speed, the start and stop of irradiation of the laser light L in the irradiation unit 3 is controlled based on the θ information with the focusing area C positioned along the edge of the effective area R in the target object 11. This forms a modified area 12 along the line A (edge of the effective area R) as shown in FIG. 24(b) and FIG. 24(c). The formed modified area 12 includes a modified spot and a crack extending from the modified spot.

In the trimming process, the control unit 6 executes the removal process. Specifically, as shown in (a) of FIG. 25, without rotating the stage 2, the laser light L is irradiated in the removal area E, and the irradiation unit 3 is moved along the X direction to move the focusing area C of the laser light L relative to the object 11 in the X direction. After rotating the stage 2 by 90°, the laser light L is irradiated in the removal area E, and the irradiation unit 3 is moved along the X direction to move the focusing area C of the laser light L relative to the object 11 in the X direction.

As a result, as shown in (b) of FIG. 25, a modified region 12 is formed along a line extending to divide the removal region E into four equal parts when viewed from the Z direction. The formed modified region 12 includes a modified spot and a crack extending from the modified spot. This crack may reach at least one of the first surface 11a and the second surface 11b, or may not reach at least one of the first surface 11a and the second surface 11b. Thereafter, as shown in (a) and (b) of FIG. 26, the removal region E is removed with the modified region 12 as a boundary, for example, by using a jig or air. As a result, a semiconductor device 11K is formed from the target object 11.

26(c), the peeled surface 11c of the semiconductor device 11K is subjected to finish grinding or polishing with an abrasive material KM such as a grindstone. If the object 11 is peeled off by etching, the polishing can be simplified. As a result of the above, the semiconductor device 11M is obtained.

Next, the trimming process will be described in more detail. As shown in FIG. 27, the object 11 has a plate shape. The object 11 has a crystal structure including a (100) plane, one (110) plane, another (110) plane, a first crystal orientation K1 perpendicular to the one (110) plane, and a second crystal orientation K2 perpendicular to the other (110) plane. The first surface 11a of the object 11 is a (100) plane. The object 11 is supported on the stage 2 so that the (100) plane (i.e., the first surface 11a) is the incident surface of the laser light L. The object 11 is, for example, a silicon wafer made of silicon. The (110) plane is a cleavage plane. The first crystal orientation K1 and the second crystal orientation K2 are cleavage directions, that is, directions in which cracks are most likely to extend in the object 11. The first crystal orientation K1 and the second crystal orientation K2 are perpendicular to each other.

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

Line A is set on the object 11 as a planned trimming line. Line A is a line planned for forming the modified region 12. Line A extends in a ring shape inside the outer edge of the object 11. Line A here extends in a circular shape. Line A is set on the boundary between the effective region R and the removal region E of the object 11. Line A can be set in the control unit 6. Line A is a virtual line, but may also be an actually drawn line. Line A may also be specified by coordinates.

The control unit 6 acquires object information regarding the object 11. The object information includes, for example, information regarding the crystal orientation (first crystal orientation K1 and second crystal orientation K2) of the object 11, and alignment information regarding the position of the object 11 in the 0° direction and the diameter of the object 11. The control unit 6 can acquire the object information based on an image captured by an alignment camera, and input by user operation or external communication, etc.

The control unit 6 also acquires line information regarding the line A. The line information includes information about the line A and information about the direction of movement (also called the "processing progress direction") when the light collection area C is moved relatively along the line A. For example, the processing progress direction is the tangent direction of the line A that passes through the light collection area C located on the line A. The control unit 6 can acquire the line information based on input from a user's operation or external communication, etc.

Furthermore, the control unit 6 determines the longitudinal direction orientation when the focusing area C is moved relatively along the line A based on the acquired object information and line information so that the longitudinal direction of the beam shape intersects with the processing progress direction. Specifically, the control unit 6 determines the orientation of the longitudinal direction NH to a first orientation and a second orientation based on the object information and line information. The first orientation is the longitudinal direction orientation of the beam shape when the focusing area C is moved relatively along the first area A1 of the line A. The second orientation is the longitudinal direction orientation of the beam shape when the focusing area C is moved relatively along the second area A2 of the line A. Hereinafter, the "longitudinal direction orientation of the beam shape" is also simply referred to as the "orientation of the beam shape."

The first region A1 is an arc-shaped region, and as an example, when the point where the second crystal orientation K2 and line A intersect perpendicularly is defined as 0°, the point where the first crystal orientation K1 and line A intersect perpendicularly is defined as 90°, and the midpoint on line A between 0° and 90° is defined as 45°, the first region A1 includes the regions from 0° to 45°, 90° to 135°, 180° to 225°, and 270° to 315°, and the second region A2 is an arc-shaped region, and includes the regions from 45° to 90°, 135° to 180°, 225° to 270°, and 315° to 360°. In this case, the 45° and 225° points are points where the third crystal orientation K3 perpendicular to the (100) plane and the line A intersect at right angles, and the 135° and 315° points are points where the fourth crystal orientation K4 perpendicular to the (100) plane and the line A intersect at right angles.

In this way, the line A includes a plurality of first regions A1 and a plurality of second regions A2 arranged alternately at 45° in a counterclockwise direction. However, the above-mentioned angle range of the first region A1 and the second region A2 can be arbitrarily changed depending on where the 0° point is set. For example, if the point where the first crystal orientation K1 and the line A intersect perpendicularly is set to 0° (if the above-mentioned 90° point is set to 0°), the first region A1 and the second region A2 are in an angle range rotated by 90° from the above-mentioned angle range. In addition, if the 0° point is set as described above, the 315° point, which is a point rotated by 45° clockwise from the 0° point, can also be referred to as the -45° point. Furthermore, the point at the boundary (for example, 45°) between the first region A1 and the second region A2 may be included in either one of the first region A1 and the second region A2, or may be included in both.

The first region A1 includes a region where the processing angle described below is 0° or more and 45° or less, or -90° or more and -45° or less, when the light collection region C is moved relatively along the line A. The second region A2 includes a region where the processing angle described below is 45° or more and less than 90°, or -45° or more and less than 0°, when the light collection region C is moved relatively along the line A.

As shown in FIG. 28B, the processing angle α is the angle of the processing direction ND relative to the first crystal orientation K1. The processing angle α is a positive angle when viewed from the Z direction intersecting with the first surface 11a, which is the incident surface of the laser light L, and a negative angle when viewed from the Z direction in the counterclockwise direction. The processing angle α can be obtained based on the θ information of the stage 2, the object information, and the line information. When the light collection area C is moved relatively along the first area A1, for example, the processing angle α can be recognized as being 0° or more and 45° or less, or -90° or more and -45° or less. When the light collection area C is moved relatively along the second area A2, for example, the processing angle α can be recognized as being 45° or more and 90° or less, or -45° or more and 0° or less.

The first and second orientations are inclined with respect to the processing direction ND so as to approach one of the first crystal orientation K1 and the second crystal orientation K2 that has a larger angle (the one that is further away) with respect to the processing direction ND.

When the processing angle α is between 0° and 90°, the first and second orientations are as follows: The first orientation is the direction in which the longitudinal direction NH is inclined with respect to the processing direction ND toward the side approaching the second crystal orientation K2. The second orientation is the direction in which the longitudinal direction NH is inclined with respect to the processing direction ND toward the side approaching the first crystal orientation K1. The first orientation is, for example, a direction inclined by 10° to 35° from the processing direction ND toward the side approaching the second crystal orientation K2. The second orientation is, for example, a direction inclined by 10° to 35° from the processing direction ND toward the side approaching the first crystal orientation K1.

The first orientation is the orientation of the focusing area C when the beam angle β is +10° to +35°. The second orientation is the orientation of the focusing area C when the beam angle β is -35° to -10°. The beam angle β is the angle between the processing progress direction ND and the longitudinal direction NH. When viewed from the Z direction intersecting the first surface 11a, which is the incident surface of the laser light L, the angle heading counterclockwise is considered to be a positive angle, and the angle heading clockwise is considered to be a negative angle. The beam angle β can be obtained based on the orientation of the focusing area C and the processing progress direction ND.

The control unit 6 controls the start and stop of laser processing of the target object 11. The control unit 6 executes a first processing process in which the light collection area C is moved relatively along the first area A1 of the line A to form the modified area 12, and the formation of the modified area 12 in areas other than the first area A1 of the line A is stopped. The control unit 6 executes a second processing process in which the light collection area C is moved relatively along the second area A2 of the line A to form the modified area 12, and the formation of the modified area 12 in areas other than the second area A2 of the line A is stopped.

The control unit 6 can switch between forming the modified region 12 and stopping the formation as follows. For example, in the irradiation unit 3, the start and stop (ON/OFF) of the irradiation (output) of the laser light L can be switched to switch between forming the modified region 12 and stopping the formation. Specifically, when the laser oscillator is composed of a solid-state laser, the start and stop of the irradiation of the laser light L is switched at high speed by switching ON/OFF of a Q switch (AOM (acousto-optical modulator), EOM (electro-optical modulator), etc.) provided in the resonator. When the laser oscillator is composed of a fiber laser, the start and stop of the irradiation of the laser light L is switched at high speed by switching ON/OFF of the output of the semiconductor laser that constitutes the seed laser and the amplifier (excitation) laser. When the laser oscillator uses an external modulation element, the ON/OFF of the irradiation of the laser light L is switched at high speed by switching ON/OFF of an external modulation element (AOM, EOM, etc.) provided outside the resonator.

Alternatively, the control unit 6 may switch between forming the modified region 12 and stopping the formation as follows. For example, a mechanical mechanism such as a shutter may be controlled to open and close the optical path of the laser light L, thereby switching between forming the modified region 12 and stopping the formation. The formation of the modified region 12 may be stopped by switching the laser light L to CW light (continuous wave). The formation of the modified region 12 may be stopped by displaying a pattern (e.g., a pear-skin pattern that scatters the laser) that makes the focusing state of the laser light L in a state where it cannot be modified on the liquid crystal layer 76 of the spatial light modulator 7. The formation of the modified region 12 may be stopped by controlling an output adjustment unit such as an attenuator to reduce the output of the laser light L so that the modified region 12 cannot be formed. The formation of the modified region 12 may be stopped by switching the polarization direction. The formation of the modified region 12 may be stopped by scattering (scattering) the laser light L in a direction other than the optical axis and cutting it.

The control unit 6 adjusts the orientation of the light collection area C by controlling the spatial light modulator 7. When performing the first processing process, the control unit 6 adjusts the orientation of the light collection area C to a first orientation. When performing the second processing process, the control unit 6 adjusts the orientation of the light collection area C to a second orientation. As an example, the control unit 6 adjusts the longitudinal direction NH of the light collection area C so that it changes within a range of ±35° with respect to the processing progress direction ND.

The above-mentioned laser processing apparatus 1 performs the following trimming processing.

In the trimming process, first, the stage 2 is rotated and the irradiation unit 3 on which the camera is mounted is moved along the X and Y directions so that the alignment camera is positioned directly above the alignment target 11n of the object 11 and the camera is focused on the alignment target 11n.

Next, an image is captured by an alignment camera. The position of the object 11 in the 0° direction is acquired based on the image captured by the camera. The control unit 6 acquires object information and line information based on the image captured by the camera and input by user operation or external communication, etc. The object information includes alignment information related to the position and diameter of the object 11 in the 0° direction. As described above, since the alignment object 11n has a certain relationship in the θ direction with respect to the position in the 0° direction, the position in the 0° direction can be acquired by obtaining the position of the alignment object 11n from the captured image. The diameter of the object 11 can be acquired based on the image captured by the camera. The diameter of the object 11 may be set by input from the user.

Next, based on the acquired object information and line information, the control unit 6 determines a first orientation and a second orientation as the orientation of the longitudinal direction NH of the light collection area C when the light collection area C is moved relatively along the line A.

Next, the stage 2 is rotated to position the object 11 in the 0° direction. In the X direction, the irradiation unit 3 is moved along the X and Y directions so that the light collection area C is located at a predetermined trimming position. For example, the predetermined trimming position is a predetermined position on the line A on the object 11.

Next, rotation of stage 2 is started. Tracking of first surface 11a is started by a distance measurement sensor (not shown). Before the distance measurement sensor starts tracking, it is confirmed in advance that the position of light collection area C is within the range measurable by the distance measurement sensor. When the rotation speed of stage 2 becomes constant (uniform speed), irradiation of laser light L by irradiation unit 3 is started.

By switching the irradiation of the laser light L on and off by the control unit 6 while rotating the stage 2, the light collection area C is moved relatively along the first area A1 of the line A to form the modified area 12, as shown in (a) of Figure 28, and the formation of the modified area 12 in areas other than the first area A1 of the line A is stopped (first processing step). As shown in (b) of Figure 28, when the first processing step is performed, the control unit 6 adjusts the orientation of the light collection area C so that it has the first orientation. In other words, the orientation of the light collection area C in the first processing step is fixed in the first orientation.

Next, while rotating the stage 2, the control unit 6 switches the irradiation of the laser light L on and off, thereby moving the light collection area C relatively along the second area A2 of the line A to form the modified area 12, as shown in (a) of Figure 29, and stopping the formation of the modified area 12 in areas other than the first area A1 of the line A (second processing step). As shown in (b) of Figure 29, when performing the second processing step, the control unit 6 adjusts the orientation of the light collection area C so that it has the second orientation. In other words, the orientation of the light collection area C in the second processing step is fixed in the second orientation.

The above-described first and second processing steps are repeatedly performed by changing the position of the trimming predetermined position in the Z direction. As a result, inside the target object 11, a plurality of rows of modified regions 12 are formed in the Z direction along the peripheral line A of the effective region R.
[First embodiment of laser processing]

The above describes findings regarding the formation of diagonal cracks and an example of trimming processing. Here, an embodiment of laser processing in which diagonal cracks are formed during trimming processing will be described. Figure 30 is a diagram showing an object to be laser processed in one embodiment. (a) of Figure 30 is a plan view, and (b) of Figure 30 is a side view. Figure 31 is a cross-sectional view of the object shown in Figure 30.

30 and 31, the object 100 includes the object 11 described above and an object 11R which is a separate member from the object 11. The object 11R is, for example, a silicon wafer. The object 11 includes a device layer 110 which includes a plurality of functional elements and is formed on the second surface 11b. The object 11R includes a device layer 110R which includes a plurality of functional elements and is formed on the first surface 11Ra of the object 11R. The object 11 and the object 11R are bonded together by arranging the device layer 110 and the device layer 110R so as to face each other and joining them together, thereby constituting the object 100.

Here, a modified region 12 and a crack 13 extending from the modified region 12 are formed in the object 11, and a trimming process is performed to cut off a removal region E of the object 11 with the modified region 12 and the crack 13 as boundaries. More specifically, the object 11 includes a first portion 15A and a second portion 15B arranged in order from the second surface 11b (opposite surface) side opposite to the first surface 11a which is the incident surface of the laser light L. In the first portion 15A, the modified region 12 is formed so as to form a crack 13 extending obliquely with respect to the Z direction (hereinafter, sometimes referred to as a "diagonal crack"), and in the second portion 15B, the modified region 12 is formed so as to form a crack 13 extending along the Z direction (hereinafter, sometimes referred to as a "vertical crack"). Note that the line R1 in FIG. 31 indicates a line on which a diagonal crack is to be formed, and the line R2 indicates a line on which a vertical crack is to be formed.

Therefore, at least when processing the first portion 15A, the above-mentioned trimming process and the process for generating the oblique crack are used in combination. That is, when processing the first portion 15A, the beam shape is shaped so that the longitudinal direction NH is inclined with respect to the processing direction ND so as to approach one of the first crystal orientation K1 and the second crystal orientation K2 that has a larger angle with the processing direction ND, and the modified region 12 and the crack 13 are formed along the line A, and the crack 13 becomes an oblique crack.

More specifically, when processing the first area A1 of the line A, the laser light L is shaped to have a focusing area C of a first shape Q1 in a first orientation as shown in (b) of Fig. 28, and when processing the second area A2 of the line A, the laser light L is shaped to have a focusing area C of a second shape Q2 in a second orientation as shown in (b) of Fig. 29. The following processing test was carried out for such processing.

Figure 32 is a plan view of the object shown in Figure 30. As shown in Figure 32, here, for the second region A2 of the line A from the 0° point, which is the intersection point of the line A and the second crystal orientation K2, to the -45° point, which is the intersection point of the line A and the fourth crystal orientation K4, the processing was actually performed in each case of moving the light collection region C relatively with the processing progress direction ND as the forward direction ND1, and moving the light collection region C relatively with the processing progress direction ND as the reverse direction ND2, and the cross-section was observed. Here, in order to process the second region A2, the light collection region C is made to have the second shape Q2 shown in Figure 29 (b). Also, the direction CD in which the oblique crack extends is the direction from the center side of the object 11 toward the outside (see Figure 29 (b)).

Therefore, as shown in (b) of Figure 29, when the processing direction ND is the forward direction ND1, the inclination direction of the longitudinal direction NH of the light collection area C relative to the processing direction ND and the direction CD in which the diagonal crack extends are on the same side, while when the processing direction ND is the reverse direction ND2 (when the direction of the arrow of the processing direction ND is reversed), the inclination direction of the longitudinal direction NH relative to the processing direction ND and the direction CD in which the diagonal crack extends are on opposite sides to each other. Note that the forward direction ND1 is the counterclockwise direction, and the reverse direction ND2 is the clockwise direction.

Figures 33 and 34 are cross-sectional photographs showing the results of processing. Figure 33 shows the results of processing in the forward direction ND1, with (a) to (d) being cross-sectional photographs at the points of 0°, -15°, -30°, and -45°, respectively. Figure 34 shows the results of processing in the reverse direction ND2, with (a) to (d) being cross-sectional photographs at the points of 0°, -15°, -30°, and -45°, respectively.

As shown in Figures 33 and 34, good machining results were obtained from 0° to -45° when machining in the forward direction ND1, where the direction of the longitudinal direction NH and the direction of the diagonal cracks CD are on the same side of the machining direction ND. However, when machining in the reverse direction ND2, where the direction of the longitudinal direction NH and the direction of the diagonal cracks CD are on the opposite side of the machining direction ND, irregularities FN reaching the underside were generated at the -45° point (Figure 34 (d)), and a deterioration in quality was confirmed. From this, it was understood that the relationship between the direction of the inclination of the longitudinal direction NH with respect to the machining direction ND and the direction of the diagonal cracks CD with respect to the machining direction ND affects the machining quality. Based on this understanding, another machining test was conducted.

Figure 35 is a schematic diagram for explaining the processing test. Figure 36 is a schematic diagram showing the relationship between the processing direction, the beam shape, and the oblique crack in the processing test. As shown in Figures 35 and 36, in this processing test, the direction that is 45° to the (110) plane when viewed from the Z direction is the processing direction ND, and for each of the forward direction ND1 and the reverse direction ND2, processing was performed when the direction CD in which the oblique crack extends was the forward direction CD1 and the reverse direction CD2. That is, for a total of four combinations, two combinations in the forward and reverse directions of the processing direction ND and two combinations in the forward and reverse directions of the direction CD in which the oblique crack extends, processing was performed when the beam shape of the focused area C was the first shape Q1 and the second shape Q2 (a total of eight processings).

Figure 37 is a table showing the results of the machining tests shown in Figures 35 and 36. As shown in Figure 37, for a total of eight machining methods, when the direction CD in which the diagonal crack extends was set to the forward direction CD1, good machining results ("A" in the table in Figure 37) were obtained when the beam shape of the focusing area C was set to the second shape Q2 and the machining direction ND was set to the forward direction ND1, and when the beam shape of the focusing area C was set to the first shape Q1 and the machining direction ND was set to the reverse direction ND2.

In addition, for a total of eight types of processing, when the direction CD of the oblique crack was set to the reverse direction CD2, good processing results were obtained when the beam shape of the focusing area C was set to the first shape Q1 and the processing direction ND was set to the forward direction ND1, and when the beam shape of the focusing area C was set to the second shape Q2 and the processing direction ND was set to the reverse direction ND2. From this, it was found that when processing a point at least at 45°, good processing results can be obtained when the forward/reverse of the processing direction ND is adjusted and the inclination direction of the longitudinal direction NH of the focusing area C relative to the processing direction ND and the direction CD of the oblique crack are on the same side.

Note that, if the point where the second crystal orientation K2 and line A intersect perpendicularly is taken as 0°, the 45° point is the point where the third crystal orientation K3, which is perpendicular to the (100) plane, intersects perpendicularly to line A, and is equivalent to the -45° point where the fourth crystal orientation K4, which is also perpendicular to the (100) plane, intersects perpendicularly to line A.

Based on the above findings, further processing tests were performed. FIG. 38 is a table showing the results of the processing tests. Among the conditions shown in the table of FIG. 38, good processing results (rating "A" or rating "B" in the table of FIG. 38) were obtained under conditions IR1 and IR2 in which the beam shape in the first region A1 was the first shape Q1 and the beam shape in the second region A2 was the second shape Q2, and the inclination direction of the longitudinal direction NH of the light-collecting region C with respect to the processing progress direction ND and the direction CD in which the oblique crack extends were on the same side. The ratings shown in FIG. 38 are in the order of "A", "B", "C", "D", and "E" (i.e., "A" is the best and "E" is the worst).

Condition IR1 is a condition in which the processing direction ND is the forward direction ND1 for the second region A2 from the point of 0° to the point of -45° when the point where the first crystal orientation K1 and the line A intersect is 0°, and the beam shape of the light collection region C is the second shape Q2. Condition IR2 is a condition in which the processing direction ND is the reverse direction ND2 for the first region A1 from the point of -45° to the point of -90° when the point where the first crystal orientation K1 and the line A intersect is 0°, and the beam shape of the light collection region C is the first shape Q1.

On the other hand, among the conditions shown in the table of FIG. 38, under the condition that the beam shape is the first shape Q1 in the first region A1 and the condition that the beam shape is the second shape Q2 in the second region A2, the results of the conditions IR3 and IR4, in which the inclination direction of the longitudinal direction NH of the light collection region C with respect to the processing direction ND is not on the same side as the direction CD in which the oblique crack extends, were inferior to those of the conditions IR1 and IR2, but generally good results were obtained except at -45°. On the other hand, among the conditions shown in the table of FIG. 38, under the condition IR5, in which the beam shape is the second shape Q2 in the first region A1, and the condition IR6, in which the beam shape is the first shape Q1 in the second region A2, good results were generally not obtained regardless of the forward or reverse direction of the processing direction ND.

Note that (a) of FIG. 39 is an example of a cross-sectional photograph corresponding to the rating "E" in the table of FIG. 38, (b) of FIG. 39 is an example of a cross-sectional photograph corresponding to the rating "D" in the table of FIG. 38, (c) of FIG. 39 is an example of a cross-sectional photograph corresponding to the rating "C" in the table of FIG. 38, (d) of FIG. 39 is an example of a cross-sectional photograph corresponding to the rating "B" in the table of FIG. 38, and (e) of FIG. 39 is an example of a cross-sectional photograph corresponding to the rating "A" in the table of FIG. 38. As shown in FIG. 39, the ratings "A" and "B" indicate good processing results in which no irregularities are formed that reach the underside. Furthermore, the rating "C" indicates a generally good result, although there is a small amount of irregularities that reach the underside. On the other hand, the ratings "D" and "E" indicate a relatively large amount of irregularities that reach the underside, indicating poor results.

The results of the processing tests shown in Figures 38 and 39 confirmed the correctness of the findings obtained from the results of the processing tests shown in Figure 37.

In this embodiment, laser processing is performed based on the above findings. Here, first, the first portion 15A (see FIG. 31) of the object 11 is processed. That is, while rotating the stage 2, the control unit 6 switches the irradiation of the laser light L on and off, so that the light collection area C is moved relatively along the first area A1 of the line A to form the modified area 12, as shown in FIG. 40(a), and the formation of the modified area 12 in the area (second area A2) other than the first area A1 of the line A is stopped (first processing).

As shown in (b) of Figure 40, in the first processing, the rotation direction of the stage 2 is controlled under the control of the moving unit 4 of the control unit 6, so that the processing progress direction ND is set to the reverse direction ND2. Also, in the first processing, since the processing is of the first area A1, the spatial light modulator 7 shapes the laser light L under the control of the control unit 6, so that the beam shape of the focused area C is set to the first shape Q1. Furthermore, here, the direction CD in which the oblique crack extends is set to the positive direction CD1 so that it inclines from the center of the object 11 toward the outside with respect to the Z direction as it approaches the second surface 11b (see Figure 31).

Here, the method of forming the oblique crack will be specifically described. That is, in the first processing, as shown in FIG. 41, the position of the light collection area C1 in the Z direction intersecting with the first surface 11a, which is the incident surface of the laser light L1 in the object 11, is set to the first Z position Z1, and the light collection area C1 is moved relatively along the line A (X direction) to form the modified area (first modified area) 12a and the crack (first crack) 13a extending from the modified area 12a in the object 11 (first formation). In this first formation, the position of the light collection area C1 in the Y direction, which is along the first surface 11a and intersects with the X direction, is set to the first Y position Y1.

In the first processing, the position of the focusing area C2 of the laser light L2 in the Z direction is set to a second Z position Z2 closer to the first surface 11a (incident surface) than the first Z position Z1 of the focusing area C1 in the first formation, while the focusing area C2 is moved relatively along the line A (X direction) to form the modified area 12b (second modified area) and the crack (second crack) 13b extending from the modified area 12b (second formation). In this second formation, the position of the focusing area C2 in the Y direction is set to a second Y position Y2 shifted from the first Y position Y1 of the focusing area C1. In the second formation, the laser light L2 is modulated so that the beam shape of the focusing area C2 in the YZ plane S including the Y direction and the Z direction becomes an inclined shape that is inclined in the direction of the shift at least on the first surface 11a side from the center of the focusing area C2 (the beam shape of the focusing area C2 when viewed from the Z direction is the first shape Q1). As a result, the crack 13 is formed so as to be inclined in the direction of the shift in the YZ plane S. The control of the beam shape in the YZ plane S is as explained in the knowledge regarding the oblique crack above.

In addition, here, in the first formation, as in the second formation, the laser light L1 is modulated so that the beam shape of the focusing area C1 in the YZ plane S including the Y direction and the Z direction becomes an inclined shape that is inclined in the direction of the shift at least on the first surface 11a side from the center of the focusing area C1 (in this case, the beam shape of the focusing area C1 when viewed from the Z direction is the first shape Q1). As a result, as shown in (b) of FIG. 41, in the first area A1 of the line A, the crack 13a and the crack 13b are connected, and a crack 13 (diagonal crack 13F) that extends diagonally across the modified areas 12a and 12b is formed. The diagonal crack 13F may or may not reach the second surface 11b of the object 11 (can be set appropriately according to the required processing mode).

The laser beams L1 and L2 can be generated by splitting the laser beam L into two, for example, by modulating the laser beam L by displaying a pattern for splitting the laser beam L on the spatial light modulator 7. In this case, the first formation and the second formation are performed simultaneously. However, the laser beams L1 and L2 may be different laser beams, in which case the first formation and the second formation are performed at different times. The focusing areas C1 and C2 are focusing areas of the laser beams L1 and L2, respectively, which correspond to the focusing area C of the laser beam L.

On the other hand, in this embodiment, while rotating the stage 2, the control unit 6 switches the irradiation of the laser light L on and off, thereby relatively moving the focusing area C along the second area A2 of the line A to form the modified area 12, as shown in (a) of Figure 42, and stopping the formation of the modified area 12 in the area (first area A1) other than the second area A2 of the line A (second processing).

As shown in (b) of FIG. 42, in the second processing, the rotation direction of the stage 2 is controlled under the control of the moving unit 4 of the control unit 6, so that the processing direction ND is set to the forward direction ND1. That is, between the first processing and the second processing, the forward/reverse processing direction ND (whether it is the forward direction ND1 or the reverse direction ND2) is switched. In addition, since the second processing is processing of the second area A2, the spatial light modulator 7 shapes the laser light L under the control of the control unit 6, so that the beam shape of the focused area C is set to the second shape Q2. Furthermore, here, the direction CD in which the oblique crack extends is set to the forward direction CD1 so that it inclines from the center of the object 11 toward the outside with respect to the Z direction as it approaches the second surface 11b (see FIG. 31).

Here, the method of forming the oblique crack will be specifically described. That is, in the second processing, as shown in (a) of FIG. 43, the position of the light collection area C1 in the Z direction intersecting with the first surface 11a, which is the incident surface of the laser light L1 in the object 11, is set to the first Z position Z1, while the light collection area C1 is moved relatively along the line A (X direction), to form the modified area (first modified area) 12a and the crack (first crack) 13a extending from the modified area 12a in the object 11 (first formation). In this first formation, the position of the light collection area C1 in the Y direction, which is along the first surface 11a and intersects with the X direction, is set to the first Y position Y1.

In the second formation, the position of the focusing region C2 of the laser light L2 in the Z direction is set to a second Z position Z2 closer to the first surface 11a (incident surface) than the first Z position Z1 of the focusing region C1 in the first formation, while the focusing region C2 is moved relatively along the line A (X direction) to form the modified region 12b (second modified region) and the crack (second crack) 13b extending from the modified region 12b (second formation). In this second formation, the position of the focusing region C2 in the Y direction is set to a second Y position Y2 shifted from the first Y position Y1 of the focusing region C1. In the second formation, the laser light L2 is modulated so that the beam shape of the focusing region C2 in the YZ plane S including the Y direction and the Z direction becomes an inclined shape that is inclined in the direction of the shift at least on the first surface 11a side from the center of the focusing region C2 (the beam shape of the focusing region C2 when viewed from the Z direction is the second shape Q2). As a result, a crack 13 is formed in the YZ plane S so as to be inclined in the direction of the shift.

In addition, here, in the first formation, as in the second formation, the laser light L1 is modulated so that the beam shape of the focusing area C1 in the YZ plane S including the Y direction and the Z direction becomes an inclined shape that is inclined in the direction of the shift at least on the first surface 11a side from the center of the focusing area C1 (in this case, the beam shape of the focusing area C1 when viewed from the Z direction is the second shape Q2). As a result, as shown in (b) of FIG. 43, in the second area A2 of the line A, the crack 13a and the crack 13b are connected, and a crack 13 (diagonal crack 13F) that extends diagonally across the modified areas 12a and 12b is formed. The crack 13 may or may not reach the second surface 11b of the object 11 (can be set appropriately according to the required processing mode). The modulation pattern for making the beam shape into an inclined shape is as described above.

That is, the modulation pattern here includes a coma aberration pattern for imparting coma aberration to the laser light L, and at least in the second formation, the control unit 6 can perform the first pattern control for making the beam shape of the light collection area C2 an inclined shape by controlling the magnitude of coma aberration due to the coma aberration pattern. As described above, imparting coma aberration to the laser light L is synonymous with offsetting the spherical aberration correction pattern.

Therefore, the modulation pattern here includes a spherical aberration correction pattern Ps for correcting the spherical aberration of the laser light L, and at least in the second formation, the control unit 6 may perform second pattern control to make the beam shape of the focusing region C2 an inclined shape by offsetting the center Pc of the spherical aberration correction pattern Ps in the Y direction relative to the center of the entrance pupil surface 33a of the focusing lens 33.

Alternatively, in the second formation, the control unit 6 may perform a third pattern control to make the beam shape in the light collection region C2 an inclined shape by causing the spatial light modulator 7 to display a modulation pattern asymmetric with respect to the axis Ax along the X direction. The modulation pattern asymmetric with respect to the axis Ax may be a modulation pattern PG1 to PG4 including a grating pattern Ga, or a modulation pattern PE including elliptical patterns Es and Ew (or may include both).

That is, the modulation pattern here includes elliptical patterns Es, Ew for making the beam shape of the focusing area C in the XY plane an elliptical shape with the X direction as the longitudinal direction, and in the second formation, the control unit 6 may perform a fourth pattern control for making the beam shape of the focusing area C2 an inclined shape by displaying the modulation pattern PE on the spatial light modulator 7 so that the intensity of the elliptical patterns Es, Ew is asymmetric with respect to the axis Ax along the X direction.

Furthermore, in the second formation, the control unit 6 may perform a fifth pattern control to make the beam shape of the light collection area C an inclined shape by causing the spatial light modulator 7 to display a modulation pattern (e.g., the above-mentioned axicon lens pattern PA) for forming a plurality of light collection areas C arranged along the shift direction in the YZ plane S. The above various patterns may be arbitrarily combined and superimposed. In other words, the control unit 6 can execute the first pattern control to the fifth pattern control in any combination.

The first and second formations may be performed simultaneously (multifocal processing) or sequentially (single-pass processing). That is, the control unit 6 may perform the first formation, for example, for the first region A1 of the line A, and then perform the second formation. Alternatively, the control unit 6 may perform the first and second formations simultaneously, for example, for the first region A1 of the line A set on the object 11, by causing the spatial light modulator 7 to display a modulation pattern including a branching pattern for branching the laser light L into laser light L1 and L2.

Next, in this embodiment, the second portion 15B of the object 11 (see FIG. 31) is processed. In the second portion 15B, it is not necessary to form an oblique crack, and a vertical crack is formed here. Therefore, the second portion 15B is processed by a process similar to the trimming process described above to form the modified regions 12c, 12d and the cracks (vertical cracks) 13c, 13d extending therefrom (see FIG. 45). In this case, in the second portion 15B, the first process and the second process are performed without switching the forward and reverse of the processing progress direction ND between the first region A1 and the second region A2.

However, in the above-mentioned trimming process, in order to suppress deterioration of the quality of the trimmed surface, the beam shape is set to the first shape Q1 when processing the first area A1 (first process), and the beam shape is set to the second shape Q2 when processing the second area A2 (second process). However, in the second part 15B, the longitudinal direction NH of the light-focusing area C is set to be along the processing progress direction ND (not inclined relative to the processing progress direction ND), and the light-focusing area C may be moved relative to the line A continuously throughout the entire line A without turning on and off the irradiation of the laser light L at the boundary between the first area A1 and the second area A2 to form the modified areas 12c, 12d and the cracks 13c, 13d. In other words, in the second part 15B, a process different from the first process and the second process can also be performed. Alternatively, in the second portion 15B, without switching the processing progression direction ND, a first Z processing may be performed in which the light collection area C is moved relatively along the first area A1 of the line A to form modified areas 12c, 12d along the first area A1 and cracks 13c, 13d extending from the modified areas 12c, 12d in the Z direction, and a second Z processing may be performed in which the light collection area C is moved relatively along the second area A2 of the line A to form modified areas 12c, 12d along the second area A2 and cracks 13c, 13d extending from the modified areas 12c, 12d in the Z direction, as separate processes. In this case, in the first Z processing and the second Z processing, similarly to the first processing and the second processing, the laser light L can be shaped so that the focusing area C has a longitudinal direction NH when viewed from the Z direction, and so that the longitudinal direction NH is inclined with respect to the processing progress direction NDD in a direction approaching one of the first crystal orientation K1 and the second crystal orientation K2 which has a larger angle with the processing progress direction ND.

By the above processing, as shown in Figures 44 and 45, the modified region 12 and the crack 13 are formed in the object 11 over the entire line A and over almost the entire Z direction. In particular, as shown in Figure 45, in the first portion 15A, as it moves from the first surface 11a to the second surface 11b of the object 11, the cracks 13a and 13b are formed, which are inclined from the inner position of the bonding region between the device layer 110 of the object 11 and the device layer 110R of the object 11R toward the outer edge 110e of the bonding region. In addition, the cracks 13c and 13d may be disconnected and not continuous, or may be continuous. Furthermore, the cracks 13b and 13c may be disconnected and not continuous, or may be continuous.

Then, the removal process is performed in the same manner as the trimming process described above. Specifically, without rotating the stage 2, the laser light L is irradiated in the removal area E, and the irradiation unit 3 is moved along the X direction, so that the focusing area C of the laser light L moves in the X direction relative to the object 11. After rotating the stage 2 by 90°, the laser light L is irradiated in the removal area E, and the irradiation unit 3 is moved in the X direction along the X direction, so that the focusing area C of the laser light L moves in the X direction relative to the object 11.

As a result, as shown in Fig. 46, a modified region 12 and a crack 13 extending from the modified region 12 are formed along a line extending to divide the removal region E into four equal parts when viewed from the Z direction. Then, as shown in Fig. 47(a), the removal region E is removed with, for example, a jig or air, with the modified region 12 as the boundary. As a result, a semiconductor device 11K is formed from the object 11, and an object 100K including the semiconductor device 11K is obtained.

Next, the semiconductor device 11K is ground from the first surface 11a side. Here, the second portion 15B is removed and a part of the first portion 15A is also removed. The part of the first portion 15A that is removed is the part where the modified regions 12a, 12b are formed. Therefore, the remaining part of the first portion 15A does not include the modified regions 12a, 12b. When the object 11 is peeled off by etching, the polishing can be simplified. As a result of the above, the semiconductor device 11M is formed and the object 100M including the semiconductor device 11M is obtained.

The above laser processing according to the present embodiment will be described as the configuration of the laser processing device 1. That is, the laser processing device 1 is for irradiating the object 11 with laser light L (laser light L1, L2) to form the modified region 12, and includes at least a stage 2 for supporting the object 11, an irradiation unit 3 for irradiating the laser light L toward the object 11 supported by the stage 2, movement units 4, 5 for moving the focusing area C (focusing areas C1, C2) of the laser light L relative to the object 11, and a control unit 6 for controlling the movement units 4, 5 and the irradiation unit 3. The irradiation unit 3 has a spatial light modulator 7 that shapes the laser light L so that the focusing area C has a longitudinal direction NH when viewed from the Z direction.

The control unit 6 then controls the irradiation unit 3 and the moving units 4 and 5 to relatively move the light collection area C (light collection areas C1 and C2) along the first area A1 of the line A, thereby performing a first processing process (the above-mentioned first processing) in which a modified area 12 (modified areas 12a and 12b) is formed in the object 11 along the first area A1, and an oblique crack 13F extends obliquely in the Z direction from the modified area 12 toward the second surface 11b opposite to the first surface 11a, which is the incident surface of the object 11.

Furthermore, the control unit 6 controls the irradiation unit 3 and the moving units 4 and 5 to relatively move the light collection area C (light collection areas C1, C2) along the second area A2 of the line A, thereby performing a second processing process (the above-mentioned second processing) in which a modified area 12 (modified areas 12a, 12b) is formed in the object 11 along the second area A2 and an oblique crack 13F (cracks 13a, 13b) extending from the modified area 12 toward the second surface 11b.

In the first and second processing processes, the control unit 6 controls the spatial light modulator 7 to shape the laser light L so that the focusing area C has a longitudinal direction NH when viewed from the Z direction, and the longitudinal direction NH of the focusing area C is inclined with respect to the processing progress direction ND, which is the movement direction of the focusing area C, toward one of the first crystal orientation K1 and the second crystal orientation K2 that has a larger angle with the processing progress direction ND, which is the movement direction of the focusing area C. In the first and second processing processes, the control unit 6 controls the movement units 4 and 5 to switch the forward and reverse of the processing progress direction ND between the first and second processing processes so that the inclination direction of the longitudinal direction NH is on the same side as the direction in which the oblique crack 13F extends with respect to the processing progress direction ND when viewed from the Z direction.

Next, the laser processing according to the present embodiment will be described as a step of the laser processing method. That is, the laser processing method according to the present embodiment is for forming a modified region 12 by irradiating the object 11 with laser light L (laser light L1, L2), and has a first processing step (above-mentioned first processing) in which a modified region 12 (modified region 12a, 12b) is formed in the object 11 along the first region A1 by relatively moving the focusing region C (focusing regions C1, C2) along the first region A1 of the line A set on the object 11, and an oblique crack 13F (crack 13a, 13b) extending obliquely in the Z direction from the modified region 12 toward the second surface 11b opposite to the first surface 11a, which is the incident surface of the object 11.

In addition, the laser processing method according to this embodiment includes a second processing step (the above-mentioned second processing) in which the focusing area C (focus areas C1, C2) is moved relatively along the second area A2 of the line A to form a modified area 12 (modified areas 12a, 12b) in the object 11 along the second area A2, and also form an oblique crack 13F (cracks 13a, 13b) extending from the modified area 12 toward the second surface 11b.

In the first and second processing steps, the laser light L is shaped so that the focusing area C has a longitudinal direction NH when viewed from the Z direction, and the longitudinal direction NH of the focusing area C is inclined with respect to the processing direction ND, which is the movement direction of the focusing area C, toward one of the first crystal orientation K1 and the second crystal orientation K2 that has a larger angle with the processing direction ND. In the first and second processing steps, the direction of inclination of the longitudinal direction NH is switched between the first and second processing steps so that, when viewed from the Z direction, the direction of inclination of the longitudinal direction NH is on the same side as the direction in which the oblique crack 13F extends with respect to the processing direction ND.

As described above, in the laser processing apparatus 1 and the laser processing method according to the present embodiment, the object 11 has a crystal structure including a (100) plane, one (110) plane, another (110) plane, a first crystal orientation K1 perpendicular to the one (110) plane, and a second crystal orientation K2 perpendicular to the other (110) plane. Here, in the case where the modified region 12 is formed in the object 11 along the first region A1 of the line A that moves the focusing region C of the laser light L relatively (first processing process, first processing step), and in the case where the modified region 12 is formed in the object 11 along the second region A2 of the line A (second processing process, second processing step), the laser light L is shaped so that the longitudinal direction NH of the focusing region C is inclined with respect to the processing direction ND in a direction approaching one of the first crystal orientation K1 and the second crystal orientation K2 that has a larger angle with the processing direction ND. This prevents deterioration in the quality of the trimmed surface.

On the other hand, in the laser processing apparatus 1 and the laser processing method according to this embodiment, in the first processing process and the second processing process (the same applies to the first processing step and the second processing step (hereinafter)), a diagonal crack 13F is formed that extends diagonally from the modified region 12 toward the second surface 11b of the object 11 in the Z direction (the direction intersecting the incident surface). Therefore, it is necessary to consider the relationship between the extension direction of this diagonal crack 13F and the direction of the longitudinal direction NH of the focusing region C. Then, in the laser processing apparatus 1 and the laser processing method according to this embodiment, the forward and reverse of the processing progress direction ND is switched between the first processing process and the second processing process so that, when viewed from the Z direction, the inclination direction of the longitudinal direction NH of the focusing region C is the same side as the side on which the diagonal crack 13F extends with respect to the processing progress direction ND.

As a result, in both the first region A1 and the second region A2, the direction of inclination of the longitudinal direction NH of the focusing region C relative to the processing progress direction ND and the side to which the oblique crack 13F extends are the same. Therefore, the relationship between the direction of the longitudinal direction NH of the focusing region C and the direction of inclination of the oblique crack 13F is a combination that provides relatively good quality, and quality degradation is suppressed. In this way, according to the laser processing device 1 and laser processing method of this embodiment, it is possible to form an oblique crack while suppressing quality degradation of the trimmed surface of the object 11.

In addition, in the laser processing device 1 according to the present embodiment, the target object 11 includes a first portion 15A and a second portion 15B arranged in sequence from the second surface 11b side along the Z direction. The control unit 6 performs the first processing process and the second processing process on the first portion 15A while switching the processing progress direction ND between forward and reverse, and performs the first processing process and the second processing process on the second portion 15B without switching the processing progress direction ND, and may form the modified region 12 (modified region 12c, 12d) and the crack 13 (crack 13c, 13d) extending from the modified region 12 along the Z direction on the second portion 15B. In this case, in the second portion 15B that forms the crack 13 along the Z direction, the processing progress direction ND is not switched between forward and reverse between the first processing process and the second processing process. Therefore, compared to switching the processing progress direction ND between forward and reverse between the first processing process and the second processing process, the time required for accelerating and decelerating the relative movement of the focused area C of the laser light L is reduced.

Alternatively, in the laser processing device 1 according to the present embodiment, the control unit 6 may perform the first processing process and the second processing process on the first portion 15A while switching the forward and reverse of the processing progress direction ND, and may perform a different processing process (different processing) different from the first processing process and the second processing process on the second portion 15B. In the different processing process, the control unit 6 may control the irradiation unit 3 and the moving units 4 and 5 to relatively move the focusing area C along the line A while keeping the forward and reverse of the processing progress direction ND the same throughout the line A, thereby forming a modified area 12 in the object 11 along the line A and a crack 13 extending from the modified area 12 along the Z direction. In this case, the time required for accelerating and decelerating the relative movement of the focusing area C of the laser light L is reduced compared to the case where the forward and reverse of the processing progress direction ND is switched between the first area A1 and the second area A2 of the line A in the second portion 15B.

In addition, in the laser processing device 1 according to this embodiment, in the separate processing, the control unit 6 may control the spatial light modulator 7 to shape the laser light L so that the focusing area C has a longitudinal direction NH when viewed from the Z direction, and so that the longitudinal direction NH of the focusing area C is along the processing progress direction ND. In this case, in the second portion 15B that forms the crack 13 along the Z direction, the processing of the control unit 6 is simplified compared to the case where the laser light L is shaped so that the inclination of the focusing area C of the laser light L changes between processing the first area A1 and the second area A2 of the line A.

In addition, in the laser processing device 1 according to this embodiment, the object 11 includes a joining region joined to another member (object 11R), and in the first processing process and the second processing process, the control unit 6 may form an oblique crack 13F that is inclined from an inner position of the joining region toward the outer edge 11e of the joining region as it moves from the first surface 11a to the second surface 11b. In this case, when a part of the object 11 is removed from the object 11 with the oblique crack 13F as a boundary and the remaining part of the object 11 is left, it is possible to prevent the remaining part of the object 11 from extending outward beyond the joining region of the object 11 with the other member.

In addition, in the laser processing apparatus 1 according to this embodiment, in the first processing process and the second processing process, the control unit 6 can execute a first formation process (first formation described above) in which the modified area 12a and cracks 13a extending from the modified area 12a are formed in the object 11 by setting the position of the light collection area C1 in the Z direction to a first Z position Z1 and relatively moving the light collection area C1 along the line A, and a second formation process (second formation described above) in which the modified area 12b and cracks 13b extending from the modified area 12b are formed in the object 11 by setting the position of the light collection area C2 in the Z direction to a second Z position Z2 that is closer to the first surface 11a than the first Z position Z1 and relatively moving the light collection area C2 along the line A.

In the first forming process, the control unit 6 sets the position of the light collection area C1 in the Y direction intersecting the processing progress direction ND and the Z direction to the first Y position Y1, and in the second forming process, the control unit 6 sets the position of the light collection area C2 in the Y direction to the second Y position Y2 shifted from the first Y position Y1, and by controlling the spatial light modulator 7, the shape of the light collection area C2 in the YZ plane S including the Y direction and the Z direction is shaped so that the laser light L2 is inclined in the shift direction at least on the first surface 11a side from the center of the light collection area C2, thereby forming the crack 13b so that it is inclined in the shift direction in the YZ plane S. In this way, it is possible to preferably form an oblique crack inclined with respect to the Z direction.

In addition, in the laser processing device 1 according to this embodiment, the irradiation unit 3 includes a focusing lens 33 for focusing the laser light L from the spatial light modulator 7 toward the target object 11, and in the second formation process, the control unit 6 may shape the laser light L by modulating the laser light L so that the shape of the focused area C becomes an inclined shape by controlling the modulation pattern displayed on the spatial light modulator 7. In this case, the laser light L can be easily shaped using the spatial light modulator 7.

At this time, in the laser processing device 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 second formation process, the control unit 6 may perform a first pattern control for making the shape of the light-collecting region C an inclined shape by controlling the magnitude of the coma aberration due to the coma aberration pattern. According to the knowledge of the inventor, in this case, the shape of the light-collecting region C in the YZ plane S is formed in an arc shape. That is, in this case, the shape of the light-collecting region C is inclined in the shift direction on the first surface 11a (incident surface) side from the center Ca of the light-collecting region C, and is inclined in the opposite direction to the shift direction on the opposite side to the incident surface from the center Ca of the light-collecting region C. Even in this case, it is possible to form an oblique crack 13F inclined in the shift direction.

In addition, in the laser processing apparatus 1 according to this embodiment, the object 11 includes a first portion 15A and a second portion 15B arranged in sequence from the second surface 11b side along the Z direction. The control unit 6 may perform a first processing process and a second processing process on the first portion 15A while switching the processing progress direction ND between forward and reverse, and may perform, as additional processes, a first Z processing process (the above-mentioned first Z processing) on the second portion 15B without switching the processing progress direction ND by controlling the irradiation unit 3 and the moving units 4, 5 to relatively move the light collection area C along the first area A1 of the line A, thereby forming a modified area 12 in the object 11 along the first area A1 and forming a crack 13 extending from the modified area 12 in the Z direction, and a second Z processing process (the above-mentioned second processing) by controlling the irradiation unit 3 and the moving units 4, 5 to relatively move the light collection area C along the second area A2 of the line A, thereby forming a modified area 12 in the object 11 along the second area A2 and forming a crack 13 extending from the modified area 12 in the Z direction. In this case, for the second portion 15B, the longitudinal direction NH of the focusing area C in the first area A1 and the second area A2 is set according to the processing progress direction ND, while the time required for accelerating and decelerating the relative movement of the focusing area C of the laser light L is reduced compared to the case where the processing progress direction ND is switched between forward and reverse in the first area A1 and the second area A2.

In addition, in the laser processing device 1 according to this embodiment, the modulation pattern includes a spherical aberration correction pattern for correcting the spherical aberration of the laser light L, and in the second formation process, the control unit 6 may perform second pattern control for making the shape of the light-collecting region C an inclined shape by offsetting the center of the spherical aberration correction pattern Ps in the Y direction relative to the center of the entrance pupil surface 33a of the focusing lens 33. According to the knowledge of the inventor, in this case as well, the shape of the light-collecting region C in the YZ plane S can be formed into an arc shape, as in the case of using a coma aberration pattern, and an oblique crack 13F inclined in the shift direction can be formed.

In addition, in the laser processing apparatus 1 according to this embodiment, in the second formation process, the control unit 6 may perform a third pattern control to make the shape of the light collection area C an inclined shape by causing the spatial light modulator 7 to display a modulation pattern that is asymmetric with respect to an axis along the processing progress direction ND. According to the knowledge of the inventor, in this case, the entire shape of the light collection area C in the YZ plane S can be inclined in the shift direction. Even in this case, it is possible to form an oblique crack 13F that is inclined in the shift direction.

In addition, in the laser processing device 1 according to this embodiment, the modulation pattern includes an elliptical pattern for making the shape of the light collection area C in the XY plane including the X and Y directions intersecting the Y and Z directions into an elliptical shape with the X direction as the long side, and in the second formation process, the control unit 6 may perform a fourth pattern control for making the beam shape into an inclined shape by displaying the modulation pattern on the spatial light modulator 7 so that the intensity of the elliptical pattern is asymmetric with respect to the axis line along the X direction. According to the knowledge of the inventor, even in this case, the shape of the light collection area C in the YZ plane S can be formed into an arc shape, and an oblique crack 13F inclined in the shift direction can be formed.

In the laser processing apparatus 1 according to the present embodiment, in the second forming process, the control unit 6 may perform a fifth pattern control for making the shape of the light focusing region C including the plurality of light focusing points CI an inclined shape by causing the spatial light modulator 7 to display a modulation pattern for forming the plurality of light focusing points CI of the laser light L arranged along the shift direction in the YZ plane S. According to the knowledge of the present inventor, even in this case, it is possible to form the oblique crack 13F inclined in the shift direction.
[Second embodiment of laser processing]

Next, another embodiment of laser processing in which an oblique crack is formed during trimming processing will be described. Figure 48 is a diagram showing an object of laser processing according to one embodiment. As shown in Figure 48, the object of laser processing according to this embodiment is object 11 that is bonded to object 11R to form object 100, similar to the first embodiment. However, in this embodiment, the angular range of first area A1 and second area A2 on line A is different from that in the first embodiment.

In the first embodiment, as an example, the boundary between the first region A1 and the second region A2 was set at a point of 45° or -45° where quality degradation of the trimmed surface is likely to occur. This was based on the knowledge that, even at points of 45° and -45° where quality degradation is likely to occur, quality degradation can be suppressed by adjusting the direction of advancement of the machining ND and setting the direction of inclination of the longitudinal direction NH of the light collection region C relative to the machining direction ND when machining points of 45° and -45° to the same side as the direction in which the oblique crack 13F extends.

On the other hand, as shown in the table in Figure 38, for example, when the processing direction ND during processing of the first area A1 and the second area A2 are both set to the forward direction ND1 (see the first and third tables from the top), a decrease in quality is observed at the -45° point when the beam shape of the focusing area C is set to the first shape Q1 (see the third table from the top), but good quality is obtained when the beam shape is set to the second shape Q2 (see the first table from the top), and good quality is still obtained at the -50° point.

Therefore, even if the processing direction ND during processing of the first area A1 and the second area A2 is unified to the forward direction ND1, good processing quality can be obtained over the entire angle range by setting the beam shape of the focusing area C to the second shape Q2 during processing in the angle range of about 0° to -50°, and setting the beam shape of the focusing area C to the first shape Q1 during processing in the angle range of about -50° to -90°. In fact, referring to the table in Figure 49, it can be seen that good processing quality can be obtained over the entire angle range by using condition IR7 and condition IR8 in combination.

Furthermore, for example, when the processing direction ND during processing of the first area A1 and the second area A2 is both the reverse direction ND2 (see the second and fourth tables from the top), in contrast to the example of the forward direction D1, at the -45° point, when the beam shape of the focusing area C is the second shape Q2 (see the second table from the top), a decrease in quality is observed, whereas when it is the first shape Q1 (see the fourth table from the top), good quality is obtained, and good quality is still obtained even at the -40° point.

Therefore, even if the processing direction ND during processing of the first area A1 and the second area A2 is unified to the reverse direction ND2, good processing quality can be obtained over the entire angle range if the beam shape of the focusing area C is the second shape Q2 during processing in the angle range of about 0° to -40°, and the beam shape of the focusing area C is the first shape Q1 during processing in the angle range of about -40° to -90°. In fact, referring to the table in Figure 50, it can be seen that good processing quality can be obtained over the entire angle range by using condition IR9 and condition IR10 in combination.

In other words, assuming that the laser light L is shaped so that the longitudinal direction NH of the focusing area C is inclined with respect to the processing direction ND in a direction approaching one of the first crystal orientation K1 and the second crystal orientation K2 that has a larger angle with the processing direction ND, and the processing direction of the first area A1 (the first processing described above) and the processing direction of the second area A2 (the second processing described above) are in the same order, if the boundary between the first area A1 and the second area A2 is set so that one of the first area A1 and the second area A2, where the inclination direction of the longitudinal direction NH is on the same side as the side along which the oblique crack 13F extends with respect to the processing direction ND, includes a 45° point (a -45° point in the above example), good processing quality can be obtained over the entire angle range.

The laser processing according to this embodiment is performed based on the above findings. That is, in the laser processing according to this embodiment, as shown in FIG. 48, the boundary Ks between the first region A1 and the second region A2 is set so that the inclination direction of the longitudinal direction NH is on the same side as the side on which the oblique crack 13F extends with respect to the processing progress direction ND, and includes a point of 45° (a point of -45° in the above example). In the illustrated example, the processing progress direction ND is the forward direction ND1, and the boundary Ks is set so that the second region A2 includes a point of 45°.

In particular, in this embodiment, the first region A1 is reduced by about 5° to an arc of about 40° from 0° to about 40°, and the second region A2 is expanded by about 5° to an arc of about 50° from 40° to about 90°, so that the second region A2 is longer than the first region A1 by about 10°. The machining of the first region A1 and the second region A2 is performed in the same manner as the first machining and second machining (and the first formation and second formation) described above, except that the machining progress direction ND is unified to the forward direction ND1 (or the reverse direction ND2).

The above laser processing according to the present embodiment will be described as the configuration of the laser processing device 1. That is, the laser processing device 1 is for irradiating the object 11 with laser light L (laser light L1, L2) to form the modified region 12, and includes at least a stage 2 for supporting the object 11, an irradiation unit 3 for irradiating the laser light L toward the object 11 supported by the stage 2, movement units 4, 5 for moving the focusing area C (focusing areas C1, C2) of the laser light L relative to the object 11, and a control unit 6 for controlling the movement units 4, 5 and the irradiation unit 3. The irradiation unit 3 has a spatial light modulator 7 that shapes the laser light L so that the focusing area C has a longitudinal direction NH when viewed from the Z direction.

The control unit 6 then controls the irradiation unit 3 and the moving units 4 and 5 to relatively move the light collection area C (light collection areas C1 and C2) along the first area A1 of the line A, thereby performing a first processing process (the above-mentioned first processing) in which a modified area 12 (modified areas 12a and 12b) is formed in the object 11 along the first area A1, and an oblique crack 13F (cracks 13a and 13b) extending obliquely in the Z direction from the modified area 12 toward the second surface 11b opposite to the first surface 11a, which is the incident surface of the object 11.

Furthermore, the control unit 6 controls the irradiation unit 3 and the moving units 4 and 5 to relatively move the light collection area C (light collection areas C1, C2) along the second area A2 of the line A, thereby performing a second processing process (the above-mentioned second processing) in which a modified area 12 (modified areas 12a, 12b) is formed in the object 11 along the second area A2 and an oblique crack 13F (cracks 13a, 13b) extending from the modified area 12 toward the second surface 11b.

In the first and second processing processes, the control unit 6 controls the spatial light modulator 7 to shape the laser light L so that the longitudinal direction NH of the focusing area C is inclined with respect to the processing progress direction ND, which is the movement direction of the focusing area C, toward one of the first crystal orientation K1 and the second crystal orientation K2 that has a larger angle with the processing progress direction ND, and the forward and reverse directions of the processing progress direction ND are the same in the first and second processing processes.

Then, when the point where the second crystal orientation K2 and line A intersect perpendicularly is defined as 0°, the point where the first crystal orientation K1 and line A intersect perpendicularly is defined as 90°, and the midpoint on line A between 0° and 90° is defined as 45°, the boundary Ks between the first region A1 and the second region A2 is set so that one of the first region A1 and the second region A2 includes a point of 45° where, when viewed from the Z direction, the inclination direction of the longitudinal direction NH is on the same side as the side along which the diagonal crack 13F extends with respect to the processing progress direction ND.

Next, the laser processing according to the present embodiment will be described as a step of the laser processing method. That is, the laser processing method according to the present embodiment is for forming a modified region 12 by irradiating the object 11 with laser light L (laser light L1, L2), and has a first processing step (above-mentioned first processing) in which a modified region 12 (modified region 12a, 12b) is formed in the object 11 along the first region A1 by relatively moving the focusing region C (focusing regions C1, C2) along the first region A1 of the line A set on the object 11, and an oblique crack 13F (crack 13a, 13b) extending obliquely in the Z direction from the modified region 12 toward the second surface 11b opposite to the first surface 11a, which is the incident surface of the object 11.

In addition, the laser processing method according to this embodiment includes a second processing step (the above-mentioned second processing) in which the focusing area C (focus areas C1, C2) is moved relatively along the second area A2 of the line A to form a modified area 12 (modified areas 12a, 12b) in the object 11 along the second area A2, and also form an oblique crack 13F (cracks 13a, 13b) extending from the modified area 12 toward the second surface 11b.

In the first and second processing steps, the laser light L is shaped so that the focusing area C has a longitudinal direction NH when viewed from the Z direction, and so that the longitudinal direction NH of the focusing area C is inclined with respect to the processing direction ND in a direction approaching one of the first crystal orientation K1 and the second crystal orientation K2 that has a larger angle with the processing direction ND, which is the direction of movement of the focusing area C, and the forward and reverse directions of the processing direction ND are the same in the first and second processing steps.

Then, when the point where the second crystal orientation K2 and line A intersect perpendicularly is defined as 0°, the point where the first crystal orientation K1 and line A intersect perpendicularly is defined as 90°, and the midpoint on line A between 0° and 90° is defined as 45°, the boundary Ks between the first region A1 and the second region A2 is set so that one of the first region A1 and the second region A2 includes a point of 45° where, when viewed from the Z direction, the inclination direction of the longitudinal direction NH is on the same side as the side along which the diagonal crack 13F extends with respect to the processing progress direction ND.

As described above, in the laser processing apparatus 1 and the laser processing method according to the present embodiment, the object 11 has a crystal structure including a (100) plane, one (110) plane, another (110) plane, a first crystal orientation K1 perpendicular to the one (110) plane, and a second crystal orientation K2 perpendicular to the other (110) plane. Here, in the case where the modified region 12 is formed in the object 11 along the first region A1 of the line A that moves the focusing region C of the laser light L relatively (first processing process, first processing step), and in the case where the modified region 12 is formed in the object 11 along the second region A2 of the line A (second processing process, second processing step), the laser light L is shaped so that the longitudinal direction NH of the focusing region C is inclined with respect to the processing direction ND in a direction approaching one of the first crystal orientation K1 and the second crystal orientation K2 that has a larger angle with the processing direction ND. Therefore, as shown by the above findings, deterioration in the quality of the trimmed surface is suppressed.

On the other hand, in the laser processing apparatus 1 and the laser processing method according to this embodiment, in the first processing process and the second processing process (the same applies to the first processing step and the second processing step (hereinafter the same)), a diagonal crack 13F is formed that extends obliquely in the Z direction (direction intersecting the incident surface) from the modified region 12 toward the second surface 11b (opposite surface) opposite the first surface 11a (incident surface) of the object 11. Therefore, it is necessary to consider the relationship between the extension direction of the diagonal crack 13F and the direction of the longitudinal direction NH of the focusing region C. In particular, when processing a 45° point, if the direction of the longitudinal direction NH of the focusing region C and the inclination direction of the diagonal crack 13F are opposite to each other with respect to the processing progress direction ND, a deterioration in the quality of the trimmed surface is likely to occur.

In contrast, in the laser processing device 1 and the laser processing method according to the present embodiment, the boundary Ks between the first region A1 and the second region A2 is set so that one of the first region A1 and the second region A2, in which the inclination direction of the longitudinal direction NH of the first region A1 and the second region A2 is on the same side as the side on which the oblique crack 13F extends with respect to the processing progress direction ND, includes a 45° point. In other words, the first region A1 and the second region A2, in which the direction of the longitudinal direction NH of the light collection region C and the inclination direction of the oblique crack 13F are on opposite sides to the processing progress direction ND, do not reach the 45° point on the line A. Therefore, quality degradation is suppressed. In this way, according to the laser processing device 1 and the laser processing method according to the present embodiment, it is possible to form the oblique crack 13F while suppressing quality degradation of the trimmed surface of the object 11.

Furthermore, in the laser processing apparatus 1 and the laser processing method according to this embodiment, the forward and reverse directions of the processing progress direction ND are the same in the first processing process and the second processing process. Therefore, compared to the case where the forward and reverse directions of the processing progress direction ND are switched between the first processing process and the second processing process, the time required for accelerating and decelerating the relative movement of the focusing area C of the laser light L is reduced.

In addition, in the laser processing device 1 according to this embodiment, the first region A1 and the second region A2, which has the inclination direction of the longitudinal direction NH on the same side as the side on which the oblique crack 13F extends with respect to the processing progress direction ND as viewed from the Z direction, may be longer than the other region. In this way, the lengths of the first region A1 and the second region A2 may be set to be different.

In addition, in the laser processing device 1 according to the present embodiment, the control unit 6 may perform the first processing process and the second processing process on the first portion 15A while keeping the forward and reverse directions of the processing progress direction ND the same, and may perform a different processing process (different processing) different from the first processing process and the second processing process on the second portion 15B. In the different processing process, the control unit 6 may control the irradiation unit 3 and the moving units 4 and 5 to relatively move the focusing area C along the line A while keeping the forward and reverse directions of the processing progress direction ND the same throughout the entire line A, thereby forming a modified area 12 in the object 11 along the line A and a crack 13 extending from the modified area 12 along the Z direction. In this case, the time required for accelerating and decelerating the relative movement of the focusing area C of the laser light L is reduced compared to the case where the forward and reverse directions of the processing progress direction ND are switched between the first area A1 and the second area A2 of the line A in the second portion 15B.

In addition, in the laser processing device 1 according to this embodiment, in the separate processing, the control unit 6 may control the spatial light modulator 7 to shape the laser light L so that the focusing area C has a longitudinal direction NH when viewed from the Z direction, and so that the longitudinal direction NH of the focusing area C is along the processing progress direction ND. In this case, in the second portion 15B that forms the crack 13 along the Z direction, the processing of the control unit 6 is simplified compared to the case where the laser light L is shaped so that the inclination of the focusing area C of the laser light L changes between processing the first area A1 and the second area A2 of the line A.

In addition, in the laser processing apparatus 1 according to this embodiment, as separate processing processes, the following may be executed as separate processing processes: a first Z processing process (above-mentioned first Z processing) in which the light collection area C is moved relatively along the first area A1 of the line A by controlling the irradiation unit 3 and the moving units 4, 5 without switching the processing progression direction ND for the second portion 15B, thereby forming a modified area 12 in the object 11 along the first area A1 and forming a crack 13 extending from the modified area 12 in the Z direction; and a second Z processing process (above-mentioned second processing) in which the light collection area C is moved relatively along the second area A2 of the line A by controlling the irradiation unit 3 and the moving units 4, 5, thereby forming a modified area 12 in the object 11 along the second area A2 and forming a crack 13 extending from the modified area 12 in the Z direction. In this case, for the second portion 15B, the longitudinal direction NH of the focusing area C in the first area A1 and the second area A2 is set according to the processing progress direction ND, while the time required for accelerating and decelerating the relative movement of the focusing area C of the laser light L is reduced compared to when the processing progress direction ND is switched between forward and reverse in the first area A1 and the second area A2.

In addition, in the laser processing device 1 according to this embodiment, the object 11 includes a joining region joined to another member (object 11R), and in the first processing process and the second processing process, the control unit 6 may form an oblique crack 13F that is inclined from an inner position of the joining region toward the outer edge 11e of the joining region as it moves from the first surface 11a to the second surface 11b. In this case, when a part of the object 11 is removed from the object 11 with the oblique crack 13F as a boundary and the remaining part of the object 11 is left, it is possible to prevent the remaining part of the object 11 from extending outward beyond the joining region of the object 11 with the other member.

In addition, in the laser processing apparatus 1 according to this embodiment, in the first processing process and the second processing process, the control unit 6 can execute a first formation process (first formation described above) in which the modified area 12a and cracks 13a extending from the modified area 12a are formed in the object 11 by setting the position of the light collection area C1 in the Z direction to a first Z position Z1 and relatively moving the light collection area C1 along the line A, and a second formation process (second formation described above) in which the modified area 12b and cracks 13b extending from the modified area 12b are formed in the object 11 by setting the position of the light collection area C2 in the Z direction to a second Z position Z2 that is closer to the first surface 11a than the first Z position Z1 and relatively moving the light collection area C2 along the line A.

In the first formation process, the control unit 6 sets the position of the light collection area C1 in the Y direction intersecting the processing progress direction ND and the Z direction to the first Y position Y1, and in the second formation process, the control unit 6 sets the position of the light collection area C2 in the Y direction to the second Y position Y2 shifted from the first Y position Y1, and by controlling the spatial light modulator 7, the shape of the light collection area C2 in the YZ plane S including the Y direction and the Z direction is shaped so that the laser light L2 is inclined in the shift direction at least on the first surface 11a side from the center of the light collection area C2, thereby forming the oblique crack 13F so that it is inclined in the shift direction in the YZ plane S. In this way, it is possible to preferably form an oblique crack inclined with respect to the Z direction.

In addition, in the laser processing device 1 according to this embodiment, the irradiation unit 3 includes a focusing lens 33 for focusing the laser light L from the spatial light modulator 7 toward the target object 11, and in the second formation process, the control unit 6 may shape the laser light L by modulating the laser light L so that the shape of the focused area C becomes an inclined shape by controlling the modulation pattern displayed on the spatial light modulator 7. In this case, the laser light L can be easily shaped using the spatial light modulator 7.

At this time, in the laser processing device 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 second formation process, the control unit 6 may perform a first pattern control for making the shape of the light-collecting region C an inclined shape by controlling the magnitude of the coma aberration due to the coma aberration pattern. According to the knowledge of the inventor, in this case, the shape of the light-collecting region C in the YZ plane S is formed in an arc shape. That is, in this case, the shape of the light-collecting region C is inclined in the shift direction on the first surface 11a (incident surface) side from the center Ca of the light-collecting region C, and is inclined in the opposite direction to the shift direction on the opposite side to the incident surface from the center Ca of the light-collecting region C. Even in this case, it is possible to form an oblique crack 13F inclined in the shift direction.

In addition, in the laser processing device 1 according to this embodiment, the modulation pattern includes a spherical aberration correction pattern for correcting the spherical aberration of the laser light L, and in the second formation process, the control unit 6 may perform second pattern control for making the shape of the light-collecting region C an inclined shape by offsetting the center of the spherical aberration correction pattern Ps in the Y direction relative to the center of the entrance pupil surface 33a of the focusing lens 33. According to the knowledge of the inventor, in this case as well, the shape of the light-collecting region C in the YZ plane S can be formed into an arc shape, as in the case of using a coma aberration pattern, and an oblique crack 13F inclined in the shift direction can be formed.

In addition, in the laser processing apparatus 1 according to this embodiment, in the second formation process, the control unit 6 may perform a third pattern control to make the shape of the light collection area C an inclined shape by causing the spatial light modulator 7 to display a modulation pattern that is asymmetric with respect to an axis along the processing progress direction ND. According to the knowledge of the inventor, in this case, the entire shape of the light collection area C in the YZ plane S can be inclined in the shift direction. Even in this case, it is possible to form an oblique crack 13F that is inclined in the shift direction.

In addition, in the laser processing device 1 according to this embodiment, the modulation pattern includes an elliptical pattern for making the shape of the light collection area C in the XY plane including the X and Y directions intersecting the Y and Z directions into an elliptical shape with the X direction as the long side, and in the second formation process, the control unit 6 may perform a fourth pattern control for making the beam shape into an inclined shape by displaying the modulation pattern on the spatial light modulator 7 so that the intensity of the elliptical pattern is asymmetric with respect to the axis line along the X direction. According to the knowledge of the inventor, even in this case, the shape of the light collection area C in the YZ plane S can be formed into an arc shape, and an oblique crack 13F inclined in the shift direction can be formed.

In the laser processing apparatus 1 according to the present embodiment, in the second forming process, the control unit 6 may perform a fifth pattern control for making the shape of the light focusing region C including the plurality of light focusing points CI an inclined shape by causing the spatial light modulator 7 to display a modulation pattern for forming the plurality of light focusing points CI of the laser light L arranged along the shift direction in the YZ plane S. According to the knowledge of the present inventor, even in this case, it is possible to form the oblique crack 13F inclined in the shift direction.
[Modification]

The above describes one embodiment of a laser processing apparatus and a laser processing method, but one aspect of the present disclosure is not limited to the above embodiment and may be modified.

For example, in the above example, an object 100 (bonded wafer) was given, which is formed by bonding objects 11 and 11R together, but the object of laser processing is not limited to such bonded wafers, and may be an object such as a single wafer.

In the example shown in FIG. 45, two modified regions 12a, 12b are formed in the first portion 15A using two focusing regions C1, C2. In this case, when forming the oblique crack 13F, the beam shape in at least the YZ plane S of the focusing region C2 closer to the first surface 11a is controlled. However, when forming multiple sets of modified regions 12a, 12b in the first portion 15A, it is sufficient to control the beam shape in at least the YZ plane S of the focusing region C2 closer to the first surface 11a when forming the modified region 12a, 12b closest to the second surface 11b (target object 11R).

In the above embodiment, a vertical crack is formed in the second portion 15B of the object 11. However, an oblique crack may be formed in the second portion 15B of the object 11 in the same manner as in the first portion 15A.

In addition, in the laser processing according to the first embodiment, the first processing, which is the processing of the first area A1 of the line A, and the second processing, which is the processing of the second area A2, are set on the GUI to switch at 45° intervals, such as 0°, 45°, and 90°, and the actual laser is turned on and off at the same angles. However, in an actual device, there is a delay in turning the laser on and off, which may be several hundred msec behind the setting. In other words, it is not limited to the case where the laser is turned on and off strictly at the boundary between the first area A1 and the second area A2.

In addition, in order to reduce the amount of deviation in the formation position of the modified region 12 due to the above-mentioned causes, the control unit 6 may have a correction parameter that corrects the delay time of turning the laser on and off in advance and turns the laser on and off earlier. In this case, the deviation in the formation position of the modified region 12 can be suppressed to within 1 mm. As an example, if the target object 11 is a 12-inch wafer, the circumference is approximately 942 mm, which is about 2.617 mm per degree, so the deviation in this case is kept within 1°.

As shown in the results of Figure 38, etc., it is confirmed that there is a processing quality margin of about ±5° at the switching point between the first area A1 and the second area A2. Therefore, the switching point may be intentionally shifted within the quality margin, such as 45°±5°, 45°±5°, or 90°±5°.

In the above embodiment, the modified region 12 is formed to have a ring shape when viewed from the Z direction, for example, by turning the laser ON and OFF, but strictly speaking, the modified region 12 may overlap partially (for example, by several hundred μm) at the position where the laser is turned ON and OFF, or conversely, there may be a region where the modified region 12 is not formed (for example, by several hundred μm). To prevent quality deterioration due to such influences, multiple stages may be processed by forming oblique cracks and having the effects of the first and second processes described above.

In addition, in actual processing, a run-up distance is necessary before the speed of relative movement of the focusing area C becomes constant, so switching between the forward direction ND1 and the reverse direction ND2 includes the run-up. The laser is turned OFF during the run-up, and once the speed becomes constant, the laser is turned ON at the switching point. The number of rotations during the run-up depends on the performance of the device. Also, with regard to the autofocus, it can be adjusted so that it tracks from the run-up and no overshoot occurs when forming the modified area.

Furthermore, the second embodiment is the same as the above example in terms of switching accuracy, but as for switching points such as 45° and 135°, as shown in the table of FIG. 49, switching is not performed at least at the -45° point, and switching is centered around the -50° point (in the example of the table of FIG. 50, switching is centered around the -40° point). In this case, the allowable margin of deviation is, for example, about ±2°, but depending on the beam shape (further increasing the ellipticity), it may be possible to increase it to, for example, about ±4°. On the other hand, the switching points of 0° and 90° do not need to be shifted, but may be shifted within a range of, for example, about ±4° according to the margin of quality.

A laser processing apparatus and a laser processing method are provided that are capable of forming oblique cracks while suppressing deterioration in the quality of the trim surface of an object from which the outer edge has been removed.

1...laser processing device, 2...stage (support part), 3...irradiation part, 4, 5...movement part, 6...control part, 7...spatial light modulator, 11...object, 11a...first surface (incident surface), 11b...second surface (opposite surface), 12, 12a, 12b...modified area, 13, 13a, 13b...crack, 13F...oblique crack, 33...collecting lens, A1...first area, A2...second area, K1...first crystal orientation, K2...second crystal orientation, L...laser light, C, C1, C2...collecting area, ND...processing progress direction.

Claims (13)

A laser processing apparatus for irradiating a target object with laser light to form a modified region,
A support portion for supporting the object;
an irradiation unit for irradiating the laser light toward the object supported by the support unit;
a moving unit for moving a focused region of the laser light relative to the object;
A control unit for controlling the moving unit and the irradiation unit;
Equipped with
the target object has a crystal structure including a (100) plane, one (110) plane, another (110) plane, a first crystal orientation perpendicular to the one (110) plane, and a second crystal orientation perpendicular to the other (110) plane, and is supported by the support so that the (100) plane is an incident plane of the laser light;
a ring-shaped line including an arc-shaped first region and an arc-shaped second region having a boundary with the first region is set on the object when viewed from a Z direction intersecting the incident surface;
The irradiation unit has a shaping unit that shapes the laser light so that the light collection area has a longitudinal direction when viewed from the Z direction,
The control unit is
a first processing step of controlling the irradiation unit and the moving unit to relatively move the light collecting region along the first region of the line, thereby forming the modified region in the object along the first region and forming an oblique crack extending obliquely with respect to the Z direction from the modified region toward an opposite surface of the object opposite to the incident surface;
a second processing step of controlling the irradiation unit and the moving unit to relatively move the light collecting area along the second area of the line, thereby forming the modified area in the object along the second area and forming the oblique crack extending from the modified area toward the opposite surface;
Run
In the first processing process and the second processing process, the control unit controls the shaping unit to shape the laser light so that the longitudinal direction of the light-collecting region is inclined with respect to the processing proceeding direction in a direction approaching one of the first crystal orientation and the second crystal orientation that has a larger angle with the processing proceeding direction, which is the movement direction of the light-collecting region, and controls the movement unit to make the forward and reverse directions of the processing proceeding direction the same in the first processing process and the second processing process;
When a point where the second crystal orientation and the line intersect perpendicularly is defined as 0°, a point where the first crystal orientation and the line intersect perpendicularly is defined as 90°, and a point midway between the 0° and the 90° on the line is defined as 45°, the boundary between the first region and the second region is set so that one of the first region and the second region, which is on the same side as the side on which the oblique crack extends with respect to the processing progress direction as viewed from the Z direction, includes the 45° point.
Laser processing equipment. the one of the first region and the second region is longer than the other of the first region and the second region;
2. The laser processing apparatus according to claim 1. The object includes a first portion and a second portion arranged in order from the opposite surface side along the Z direction,
The control unit executes the first processing process and the second processing process on the first portion while keeping the forward and reverse of the processing progress direction the same, and executes a separate processing process different from the first processing process and the second processing process on the second portion,
In the separate processing, the control unit controls the irradiation unit and the moving unit to relatively move the light collecting area along the line while keeping the forward and reverse directions of the processing progress the same throughout the line, thereby forming the modified area and a crack extending from the modified area along the Z direction in the target object along the line.
3. The laser processing apparatus according to claim 1 or 2. In the separate processing, the control unit controls the shaping unit to shape the laser beam so that the longitudinal direction of the light collecting region is aligned with the processing proceeding direction.
The laser processing apparatus according to claim 3. the object includes a joining region joined to another member,
In the first processing process and the second processing process, the control unit forms the oblique crack inclined from an inner position of the bonding region toward an outer edge of the bonding region as it moves from the incident surface toward the opposite surface.
The laser processing device according to any one of claims 1 to 4. In the first processing process and the second processing process, the control unit:
a first forming process for forming a first modified region as the modified region and a crack extending from the first modified region in the object by relatively moving the light collecting region along the line while setting a position of the light collecting region in the Z direction at a first Z position;
a second forming process is performed to form a second modified region as the modified region and a crack extending from the second modified region by relatively moving the light collecting region along the line while setting a position of the light collecting region in the Z direction at a second Z position closer to the incident surface than the first Z position;
In the first forming process, the control unit sets a position of the light collection area in a Y direction intersecting the processing progress direction and the Z direction to a first Y position,
In the second formation process, the control unit sets the position of the light collection area in the Y direction to a second Y position shifted from the first Y position, and forms the oblique crack so as to be inclined in the shift direction in the YZ plane by controlling the shaping unit so that the shape of the light collection area in the YZ plane including the Y direction and the Z direction is an inclined shape that is inclined in the shift direction at least on the incident surface side from the center of the light collection area.
The laser processing device according to any one of claims 1 to 5. the shaping unit includes a spatial light modulator for shaping the laser light by modulating the laser light in accordance with a modulation pattern;
the irradiation unit includes a condenser lens for condensing the laser light from the spatial light modulator toward the object,
In the second formation process, the control unit shapes the laser light by modulating the laser light so that the shape of the light collection area becomes the inclined shape by controlling the modulation pattern displayed on the spatial light modulator.
The laser processing apparatus according to claim 6. the modulation pattern includes a coma aberration pattern for imparting coma aberration to the laser light,
In the second formation process, the control unit performs a first pattern control for forming the shape of the light collection region into the inclined shape by controlling a magnitude of the coma aberration caused by the coma aberration pattern.
The laser processing apparatus according to claim 7. the modulation pattern includes a spherical aberration correction pattern for correcting spherical aberration of the laser beam,
In the second formation process, the control unit performs a second pattern control for making the shape of the light collection region into the inclined shape by offsetting the center of the spherical aberration correction pattern in the Y direction with respect to the center of the entrance pupil plane of the condensing lens.
9. The laser processing apparatus according to claim 7 or 8. In the second forming process, the control unit performs a third pattern control for making the shape of the light collection region into the inclined shape by causing the spatial light modulator to display the modulation pattern asymmetric with respect to an axis along the processing progress direction.
The laser processing apparatus according to any one of claims 7 to 9. the modulation pattern includes an elliptical pattern for making the shape of the light collection region in an XY plane including an X direction and the Y direction intersecting the Y direction and the Z direction into an elliptical shape with the X direction as a longitudinal direction,
In the second formation process, the control unit performs a fourth pattern control to cause the spatial light modulator to display the modulation pattern so that the intensity of the elliptical pattern is asymmetric with respect to an axis line along the X direction, thereby forming the shape of the light collection region into the inclined shape.
The laser processing apparatus according to any one of claims 7 to 10. In the second formation process, the control unit performs a fifth pattern control to make the shape of the light collection region including the plurality of light collection points the inclined shape by causing the spatial light modulator to display the modulation pattern for forming a plurality of light collection points of the laser light arranged along the shift direction in the YZ plane.
The laser processing apparatus according to any one of claims 7 to 11. A laser processing method for forming a modified region by irradiating a target object with laser light, comprising:
a first processing step of forming the modified region in the object along a first region of a line set on the object by relatively moving a focusing region of the laser light along the first region, and forming an oblique crack extending obliquely from the modified region toward an opposite surface of the object opposite to the incident surface of the laser light with respect to a Z direction intersecting the incident surface;
a second processing step of forming the modified region in the object along the second region by relatively moving the light collecting region along the second region of the line, and forming the oblique crack extending from the modified region toward the opposite surface;
Equipped with
the object has a crystal structure including a (100) plane, one (110) plane, another (110) plane, a first crystal orientation perpendicular to the one (110) plane, and a second crystal orientation perpendicular to the other (110) plane, and the (100) plane is the incident plane;
When viewed from the Z direction, the target object has an annular line including an arc-shaped first region and an arc-shaped second region having a boundary between the first region,
In the first processing step and the second processing step,
The laser beam is shaped so that the focusing region has a longitudinal direction when viewed from the Z direction, and the longitudinal direction of the focusing region is inclined with respect to the processing proceeding direction in a direction approaching one of the first crystal orientation and the second crystal orientation, which has a larger angle with the processing proceeding direction that is the moving direction of the focusing region, and the forward and reverse directions of the processing proceeding direction are the same in the first processing step and the second processing step;
When a point where the second crystal orientation and the line intersect perpendicularly is defined as 0°, a point where the first crystal orientation and the line intersect perpendicularly is defined as 90°, and a point midway between the 0° and the 90° on the line is defined as 45°, the boundary between the first region and the second region is set so that one of the first region and the second region, which is on the same side as the side on which the oblique crack extends with respect to the processing progress direction as viewed from the Z direction, includes the 45° point.
Laser processing method.

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