Laser processing apparatus and laser processing method

Abstract

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

Description

Technical Field

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

Background Art

[0002] Patent Document 1 describes a laser dicing apparatus. This laser dicing apparatus includes a stage for moving a wafer, a laser head for irradiating the wafer with laser light, and a control unit for controlling each part. The laser head has a laser light source that emits processing laser light for forming a modified region inside the wafer, a dichroic mirror and a condenser lens that are sequentially arranged on the optical path of the processing laser light, and an AF device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, when irradiating a wafer with laser light to form a modified region inside the wafer, part of the laser light may escape from the surface of the wafer opposite to the laser light incident surface (so-called escape light may occur). This escape light may cause damage to devices or the like formed on the surface of the wafer opposite to the laser light incident surface.

[0005] Therefore, an object of the present disclosure is to provide a laser processing apparatus and a laser processing method capable of reducing the influence of damage caused by escape light.

Means for Solving the Problems

[0006] The laser processing apparatus according to the present disclosure includes a support unit that supports an object, a light source that outputs laser light, a spatial light modulator that modulates and outputs the laser light output from the light source according to a modulation pattern, a condenser lens that condenses the laser light output from the spatial light modulator toward the object to form a condensed spot of the laser light on the object, a moving unit that relatively moves the condensed spot with respect to the object, and a control unit that controls at least the light source, the spatial light modulator, and the moving unit. The object includes a first surface that serves as an incident surface of the laser light, a second surface on the opposite side of the first surface, and a first region and a second region arranged on the second surface. A line is set for relatively moving the condensed spot so as to pass between the first region and the second region. At least a part of the line side of the first region and the second region has a different structure from each other. The control unit irradiates the object with laser light while relatively moving the condensed spot along the line in a state where the condensed spot is positioned at a first Z position on the second surface side of the first surface in the Z direction intersecting the first surface and the second surface, and in the first irradiation process, the control unit controls the modulation pattern to be displayed on the spatial light modulator such that the beam shape of the condensed spot in the YZ plane including the Y direction and the Z direction intersecting the line and the Z direction is an inclined shape inclined with respect to the Z direction at least on the first surface side of the center of the condensed spot.

[0007] The laser processing method according to the present disclosure includes a first surface, a second surface on the opposite side of the first surface, and a first region and a second region arranged along the second surface. The laser processing method irradiates a target object with a laser beam such that a line is set to pass between the first region and the second region. In the Z direction intersecting the first surface and the second surface, in a state where the condensing spot of the laser beam is positioned at a first Z position on the second surface side rather than the first surface, a first irradiation step of irradiating the target object with the laser beam while relatively moving the condensing spot along the line is provided. At least a part of the line side of the first region and the second region has different structures from each other. In the first irradiation step, the laser beam is modulated such that the beam shape of the condensing spot in the YZ plane including the Y direction and the Z direction intersecting the line and the Z direction becomes an inclined shape inclined with respect to the Z direction at least on the first surface side of the center of the condensing spot.

[0008] In this apparatus and method, the target object is irradiated with the laser beam by relatively moving the condensing spot of the laser beam along the line set on the target object. The target object includes a first surface that is the incident surface of the laser beam, a second surface on the opposite side of the first surface, and a first region and a second region arranged along the second surface. The line for relatively moving the condensing spot is set to pass between the first region and the second region. When irradiating the laser beam, the beam shape of the condensing spot in the YZ plane is made to be an inclined shape with respect to the Z direction at least on the first surface side of the center of the condensing spot. According to the findings of the present inventor, when the beam shape is made into an inclined shape in this way, it is possible to distribute the damage caused by the transmitted light according to the inclined direction.

[0009] That is, when the inclination shape of the condensing spot in the YZ plane is set to be from the second region to the first region as going from the first surface to the second surface, the damage caused by the leakage light can be unevenly distributed to the first region side. On the other hand, when the inclination shape of the condensing spot in the YZ plane is set to be from the first region to the second region as going from the first surface to the second surface, the damage caused by the leakage light can be unevenly distributed to the second region side. Here, the first region and the second region of the object have different structures from each other at least in a part on the line side. Therefore, according to this apparatus and method, by controlling the inclination direction of the condensing spot, it is possible to unevenly distribute the damage of the leakage light to the region opposite to the region where this part is a structure relatively vulnerable to the leakage light among the first region and the second region. Thereby, according to this apparatus and method, it is possible to reduce the influence of the damage caused by the leakage light.

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

[0011] In the laser processing apparatus according to the present disclosure, the first region and the second region are each a semiconductor device. The second region is provided with a wiring portion in a part. In the first irradiation process, the control unit may control the modulation pattern displayed on the spatial light modulator so that the beam shape of the condensing spot in the YZ plane has an inclined shape from the second region toward the first region as it goes from the first surface to the second surface, at least on the first surface side of the center of the condensing spot. Generally, in a semiconductor device, the wiring portion is likely to be damaged by the escape light. Therefore, by controlling the inclined shape as described above, if the damage by the escape light is unevenly distributed on the first region side opposite to the second region provided with the wiring portion, the influence of the damage by the escape light can be surely reduced.

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

[0013] In the laser processing apparatus according to the present disclosure, the modulation pattern includes a coma aberration pattern for imparting coma aberration to the laser light. In the first irradiation process, the control unit may control the beam shape to be an inclined shape by controlling the coma aberration caused by the coma aberration pattern. In this way, by controlling the coma aberration imparted to the laser light, the inclined shape of the condensing spot can be controlled.

Effects of the Invention

[0014] According to the present disclosure, a laser processing apparatus and a laser processing method capable of reducing the influence of damage by escape light can be provided.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

Figure 22

Figure 23

Figure 24

Figure 25

Figure 26

[0016] Hereinafter, an embodiment will be described in detail with reference to the drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals, and redundant descriptions may be omitted. In addition, each figure may show an orthogonal coordinate system defined by the X-axis, Y-axis, and Z-axis.

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

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

[0019] The laser irradiation unit 3 condenses the laser beam L having transmissivity with respect to the object 11 and irradiates the object 11. When the laser beam L is condensed inside the object 11 supported by the stage 2, the laser beam L is particularly absorbed in a portion corresponding to the condensing spot C (for example, the center Ca described later) of the laser beam L, and the modified region 12 is formed inside the object 11. Note that the condensing spot C is a region within a predetermined range from the position where the beam intensity of the laser beam L is the highest or the center of gravity position of the beam intensity, although a detailed description will be given later.

[0020] The modified region 12 is a region where the 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 insulating breakdown region, a refractive index change region, and the like. The modified region 12 can be formed such that cracks extend from the modified region 12 to the incident side and the opposite side of the laser beam L. Such a modified region 12 and cracks are used, for example, for cutting the object 11.

[0021] As an example, when the stage 2 is moved along the X direction and the condensing spot C is relatively moved along the X direction with respect to the object 11, a plurality of modified spots 12s are formed to be arranged in a line along the X direction. One modified spot 12s is formed by irradiation of one pulse of the laser beam L. The modified region 12 in a line is a collection of a plurality of modified spots 12s arranged in a line. Adjacent modified spots 12s may be connected to each other or separated from each other depending on the relative movement speed of the condensing spot C with respect to the object 11 and the repetition frequency of the laser beam L.

[0022] The driving unit 4 includes a first moving unit 41 that moves the stage 2 in one direction within a plane intersecting (orthogonal) to the Z direction, and a second moving unit 42 that moves the stage 2 in another direction within 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. Also, the driving unit 4 rotates the stage 2 about an axis parallel to the Z direction as the rotation axis. The driving unit 5 supports the laser irradiation unit 3. The driving unit 5 moves the laser irradiation unit 3 along the X direction, Y direction, and Z direction. By moving the stage 2 and / or the laser irradiation unit 3 in a state where the condensing spot C of the laser beam L is formed, the condensing spot C is relatively moved with respect to the object 11. That is, the driving units 4 and 5 are moving units that move at least one of the stage 2 and the laser irradiation unit 3 so that the condensing spot C of the laser beam L moves relatively with respect to the object 11.

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

[0024] FIG. 2 is a schematic diagram showing the configuration of the laser irradiation unit shown in FIG. 1. FIG. 2 shows a virtual line A indicating the plan for laser processing. As shown in FIG. 2, the laser irradiation unit 3 includes a light source 31, a spatial light modulator 7, a condenser lens 33, and a 4f lens unit 34. The light source 31 outputs a laser beam L, for example, by a pulse oscillation method. Note that the laser irradiation unit 3 may be configured to introduce the laser beam L from outside the laser irradiation unit 3 without having the light source 31. The spatial light modulator 7 modulates the laser beam L output from the light source 31. The condenser lens 33 condenses the laser beam L, which has been modulated by the spatial light modulator 7 and output from the spatial light modulator 7, toward the object 11.

[0025] As shown in FIG. 3, the 4f lens unit 34 includes a pair of lenses 34A and 34B arranged on the optical path of the laser beam L traveling from the spatial light modulator 7 toward the condenser lens 33. The pair of lenses 34A and 34B constitutes a bilateral telecentric optical system in which the modulation plane 7a of the spatial light modulator 7 and the entrance pupil plane (pupil plane) 33a of the condenser lens 33 are in an imaging relationship. Thereby, the image of the laser beam L on the modulation plane 7a of the spatial light modulator 7 (the image of the laser beam L modulated by the spatial light modulator 7) is transferred (imaged) onto the entrance pupil plane 33a of the condenser lens 33. Note that Fs in the figure indicates the Fourier plane.

[0026] As shown in FIG. 4, the spatial light modulator 7 is a spatial light modulator (SLM) of a reflective liquid crystal (LCOS: Liquid Crystal on Silicon). The spatial light modulator 7 is configured by laminating a drive circuit layer 72, a pixel electrode layer 73, a reflective film 74, an alignment film 75, a liquid crystal layer 76, an alignment film 77, a transparent conductive film 78, and a transparent substrate 79 in this order on a semiconductor substrate 71.

[0027] The semiconductor substrate 71 is, for example, a silicon substrate. The drive circuit layer 72 forms an active matrix circuit on the semiconductor substrate 71. The pixel electrode layer 73 includes a plurality of pixel electrodes 73a arranged in a matrix along the surface of the semiconductor substrate 71. Each pixel electrode 73a is formed of a metal material such as aluminum, for example. A voltage is applied to each pixel electrode 73a by the drive circuit layer 72.

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

[0029] The transparent conductive film 78 is provided on the surface of the transparent substrate 79 on the side of the alignment film 77, and faces the pixel electrode layer 73 with the liquid crystal layer 76 and the like interposed therebetween. The transparent substrate 79 is, for example, a glass substrate. The transparent conductive film 78 is formed of a light-transmissive and conductive material such as ITO, for example. The transparent substrate 79 and the transparent conductive film 78 transmit the laser beam L.

[0030] 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 the electric field is formed, in the liquid crystal layer 76, the alignment direction of the liquid crystal molecules 76a changes for each region corresponding to each pixel electrode 73a, and the refractive index changes for each region corresponding to each pixel electrode 73a. This state is a state in which the modulation pattern is displayed on the liquid crystal layer 76. The modulation pattern is for modulating the laser beam L.

[0031] That is, in a state where a modulation pattern is displayed on the liquid crystal layer 76, the laser beam L is incident on the liquid crystal layer 76 from the outside through the transparent substrate 79 and the transparent conductive film 78, reflected by the reflection film 74, and emitted from the liquid crystal layer 76 to the outside through the transparent conductive film 78 and the transparent substrate 79. Then, according to the modulation pattern displayed on the liquid crystal layer 76, the laser beam L is modulated. Thus, according to the spatial light modulator 7, by appropriately setting the modulation pattern to be displayed on the liquid crystal layer 76, modulation of the laser beam L (for example, modulation of the intensity, amplitude, phase, polarization, etc. of the laser beam L) is possible. Note that the modulation surface 7a shown in FIG. 3 is, for example, the liquid crystal layer 76.

[0032] As described above, the laser beam L output from the light source 31 is incident on the condenser lens 33 through the spatial light modulator 7 and the 4f lens unit 34, and is condensed into the object 11 by the condenser lens 33. As a result, a modified region 12 and cracks extending from the modified region 12 are formed in the object 11 at the condensed spot C. Further, by the control unit 6 controlling the drive units 4 and 5, the condensed spot C is relatively moved with respect to the object 11, so that the modified region 12 and the cracks are formed along the moving direction of the condensed spot C.

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

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

[0035] Here, one semiconductor device 11D and the area on the second surface 11b where the semiconductor device 11D is provided are referred to as a first region R1, and the other semiconductor device 11D and the area on the second surface 11b where the semiconductor device 11D is provided are referred to as a second region R2. Also, a street region Rs is interposed between the first region R1 and the second region R2, that is, between the adjacent semiconductor devices 11D. The line A is set in the street region Rs so as to pass between the first region R1 and the second region R2. Therefore, portions P1 and P2 on the line A side of the first region R1 and the second region R2 have different structures from each other in terms of whether they include at least the wiring portion W.

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

[0037] As the laser processing apparatus 1, in this step S101, the control unit 6 controls the light source 31, the spatial light modulator 7, and the drive units 4 and 5, so that in a state where the condensing spot C1 is positioned at the first Z position on the side of the second surface 11b rather than the first surface 11a in the Z direction, a first irradiation process is executed in which the object 11 is irradiated with the laser beam L while relatively moving the condensing spot C1 along line A. Thus, here, the X direction is taken as the processing progress direction FD. As a result, a modified region 12a is formed along line A inside the object 11 (at the first Z position). This step S101 and the first irradiation process can be sequentially performed for a plurality of lines A.

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

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

[0040] In the example of FIG. 7(b), a state is shown in which two rows of modified regions 12b are formed on the first surface 11a side rather than the modified region 12a formed near the first Z position. Each of the modified regions 12b is formed near the second Z position on the first surface 11a side rather than the first Z position. In this way, the modified regions 12b can be formed in any number of rows by irradiating the laser light L while positioning the condensing spot C2 of the laser light L at two or more second Z positions. In other words, the first Z position is the position in the Z direction where the condensing spot C1 is positioned when forming the modified region 12a on the second surface 11b side most when forming a plurality of rows of modified regions 12 arranged in the Z direction.

[0041] Therefore, in the step S101 and the first irradiation process, since the processing is performed with the condensing spot C1 positioned on the second surface 11b side most among a plurality of laser processing operations, it is highly necessary to consider the damage caused by the leakage light from the condensing spot C1 to the second surface 11b side, that is, the semiconductor device 11D side. Therefore, in the present embodiment, at least in the step S101 and the first irradiation process, the shape of the condensing spot C1 is made an inclined shape. Subsequently, this point will be described in detail.

[0042] FIG. 8 is a diagram showing the shape of the condensing spot and the influence of the outgoing light. FIG. 8(a) shows the beam shape of the condensing spot C1 in the YZ plane. The Y direction is a direction that intersects (is orthogonal to) both the X direction, which is the processing progress direction FD, and the Z direction. As shown in FIG. 8(a), in the process S101 and the first irradiation process, by modulating the laser beam L using the spatial light modulator 7, the beam shape of the condensing spot C1 in the YZ plane is made into an inclined shape that is inclined with respect to the Z direction, at least on the first surface 11a side of the center Ca of the condensing spot C1. According to the findings of the present inventor, when the beam shape is made into such an inclined shape, it is possible to unevenly distribute the damage caused by the outgoing light according to the inclination direction.

[0043] In the present embodiment, the beam shape of the condensing spot C1 is inclined in the negative Y direction with respect to the Z direction on the first surface 11a side of the center Ca, that is, as it goes from the first surface 11a to the second surface 11b (as it goes in the negative Z direction), it is inclined from the second region R2 to the first region R1. Further, in the present embodiment, the beam shape of the condensing spot C1 is also inclined in the negative Y direction with respect to the Z direction on the second surface 11b side of the center Ca, that is, as it goes from the first surface 11a to the second surface 11b (as it goes in the negative Z direction), it is inclined from the first region R1 to the second region R2. Thereby, the beam shape of the condensing spot C1 in the YZ plane is made into an arc shape that is convex on the positive Y direction as a whole. Note that the beam shape of the condensing spot C1 in the YZ plane is the intensity distribution of the laser beam L at the condensing spot C1 in the YZ plane.

[0044] As shown in FIG. 8(b), by controlling the inclined shape of the beam shape of the condensing spot C1 as described above, if the damage caused by the outgoing light Lt is unevenly distributed on the first region R1 side opposite to the second region R2 where the wiring portion W is provided, it is possible to surely reduce the influence of the outgoing light Lt on the wiring portion W that is easily damaged by the outgoing light Lt.

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

[0046] The position where the beam intensity is the highest and the centroid of the beam intensity can be obtained as follows. That is, the laser beam L is irradiated onto the object 11 with the output of the laser beam L lowered to such an extent (lower than the processing threshold value) that the reforming region 12 is not formed on the object 11. At the same time, the reflected light of the laser beam L from the surface (here, the second surface 11b) on the side opposite to the incident surface of the laser beam L on the object 11 is imaged by a camera at a plurality of positions F1 to F7 in the Z direction shown in FIG. 15, for example. Thereby, the position where the beam intensity is the highest and the centroid can be obtained based on the obtained image. Note that the reforming region 12 is formed near this center Ca.

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

[0048] In the example of Fig. 9, on the modulation surface 7a, the center Pc of the spherical aberration correction pattern Ps is offset by an offset amount Oy1 to the negative side in the Y direction with respect to the center Lc of the laser beam L (of the beam spot). As described above, the modulation surface 7a is imaged onto the entrance pupil surface 33a of the condenser lens 33 by the 4f lens unit 34. Therefore, the offset on the modulation surface 7a becomes an offset to the positive side in the Y direction on the entrance pupil surface 33a. That is, on the entrance pupil surface 33a, the center Pc of the spherical aberration correction pattern Ps is offset by an offset amount Oy2 to the positive side in the Y direction from the center Lc of the laser beam L and the center of the entrance pupil surface 33a (which coincides with the center Lc here).

[0049] In this way, by offsetting the spherical aberration correction pattern Ps, the beam shape of the condensing spot C1 of the laser beam L is deformed into an arcuate inclined shape as shown in Fig. 8(a). Offsetting the spherical aberration correction pattern Ps as described above is equivalent to imparting coma aberration to the laser beam L. Therefore, by including a coma aberration pattern for imparting coma aberration to the laser beam L in the modulation pattern of the spatial light modulator 7, the beam shape of the condensing spot C1 may be an inclined shape. That is, the modulation pattern includes a coma aberration pattern for imparting coma aberration to the laser beam L, and in step S101 and the first irradiation process, the control unit 6 may control the coma aberration by the coma aberration pattern to make the beam shape the inclined shape. Note that as the coma aberration pattern, a pattern corresponding to the 9th term of the Zernike polynomial (the Y component of the third-order coma aberration), which generates coma aberration in the Y direction, can be used.

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

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

[0052] Subsequently, among the plurality of focused spots shown in FIG. 10, the focused spot C1a when the level of coma aberration is "4", the focused spot C1b when the level of coma aberration is "1", and the focused spot C1c when the level of coma aberration is "0" (when no coma aberration is applied) are compared. FIG. 11 shows the profiles in the XY plane (at the position Qa) of each focused spot. As shown in FIG. 11, it can be understood that from the focused spot C1c to the focused spot C1a, as the level of coma aberration increases, the beam intensity distribution changes from a uniform state to a non-uniform state in the XY plane.

[0053] FIG. 12 is a photograph showing an example of a processing result according to the level of coma aberration. (a) of FIG. 12 shows the processing result when the level of coma aberration is "4" (condensing spot C1a), (b) of FIG. 12 shows the processing result when the level of coma aberration is "1" (condensing spot C1b), and (c) of FIG. 12 shows the processing result when the level of coma aberration is "0" (condensing spot C1c). In the examples of (a) and (b) of FIG. 12, the damage Dt due to the missing light is surely unevenly distributed in the first region R1, and no damage Dt occurs in the second region R2.

[0054] On the other hand, in the example of (c) of FIG. 12, uneven distribution of the damage Dt due to the missing light Lt is not observed, and the damage Dt occurs in both the first region R1 and the second region R2. From this result as well, it is understood that by making the beam shape of the condensing spot C1 an inclined shape as described above, the influence of the damage Dt due to the missing light Lt can be controlled. In the example of FIG. 12, a metal film is formed on the second surface 11b of the object 11 instead of the semiconductor device 11D to visualize the damage Dt. Also, the damage Dt is considered to be a so-called splash.

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

[0056] On the other hand, regarding the process S102 and the second irradiation process as well, the control unit 6 may control the spatial light modulator 7 so that the beam shape of the condensing spot C2 of the laser beam L becomes an inclined shape, similar to the process S101 and the first irradiation process. However, in the process S102 and the second irradiation process, since the processing is performed with the condensing spot C2 positioned at the second Z position relatively far from the second surface 11b, there is a low necessity to consider the damage caused by the leakage light from the condensing spot C2 to the second surface 11b side, that is, the semiconductor device 11D side. Therefore, in the present embodiment, in the process S102 and the second irradiation process, the control unit 6 controls the spatial light modulator 7 so that the beam shape of the condensing spot C2 in the YZ plane becomes a non-inclined shape along the Z direction. As an example, the non-inclined shaped condensing spot C2 can be formed in a shape similar to the condensing spot C1c by setting the level of the coma aberration of the modulation pattern displayed on the spatial light modulator 7 to "0".

[0057] As described above, in the laser processing apparatus 1 and the laser processing method according to the present embodiment, the laser beam L is irradiated onto the object 11 by relatively moving the condensing spot C of the laser beam L along the line A set on the object 11. The object 11 includes a first surface 11a that serves as an incident surface of the laser beam L, a second surface 11b on the opposite side of the first surface 11a, and a first region R1 and a second region R2 arranged along the second surface 11b. The line A along which the condensing spot C is relatively moved is set to pass between the first region R1 and the second region R2. And when irradiating the laser beam L, the beam shape of the condensing spot C1 in the YZ plane is made to be an inclined shape with respect to the Z direction at least on the first surface 11a side of the center Ca of the condensing spot C1. When the beam shape is made into an inclined shape in this way, it is possible to make the damage Dt caused by the leakage light Lt unevenly distributed according to the inclined direction.

[0058] That is, when the inclination shape of the condensing spot C1 in the YZ plane is made to go from the second region R2 to the first region R1 as going from the first surface 11a to the second surface 11b, the damage Dt caused by the leakage light Lt can be unevenly distributed to the first region R1 side. On the other hand, when the inclination shape of the condensing spot C1 in the YZ plane is made to go from the first region R1 to the second region R2 as going from the first surface 11a to the second surface 11b, the damage Dt caused by the leakage light Lt can be unevenly distributed to the second region R2 side.

[0059] Here, the first region R1 and the second region R2 of the object 11 have different structures from each other at least in a part P1, P2 on the line side. Therefore, according to the laser processing apparatus 1 and the laser processing method according to the present embodiment, by controlling the inclination direction of the condensing spot C1, among the first region R1 and the second region R2, the damage Dt of the leakage light Lt is unevenly distributed to the region opposite to the region where the part P1, P2 is a structure relatively vulnerable to the leakage light Lt. Thereby, according to the laser processing apparatus 1 and the laser processing method according to the present embodiment, it is possible to reduce the influence of the damage Dt caused by the leakage light Lt.

[0060] Further, in the laser processing apparatus 1 according to the present embodiment, the control unit 6 controls the light source 31, the spatial light modulator 7, and the drive units 4, 5 to move the condensing spot C2 along the line A while the condensing spot C2 is positioned at a second Z position farther from the second surface 11b than the first Z position in the Z direction, and executes a second irradiation process of irradiating the object 11 with the laser light L. In the second irradiation process, the control unit 6 makes the beam shape of the condensing spot C2 in the YZ plane a non-inclined shape along the Z direction by controlling the spatial light modulator 7. In this way, at the second Z position, which is farther from the second surface 11b where the first region R1 and the second region R2 are arranged and where the influence of the leakage light Lt to the second surface 11b side is small, by making the beam shape of the condensing spot C2 of the laser light L a non-inclined shape along the Z direction, it is possible to suitably extend cracks (vertical cracks) in the Z direction from the modified region 12b formed near the second Z position.

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

[0062] Furthermore, in the laser processing apparatus 1 according to the present embodiment, the modulation pattern includes a coma aberration pattern for imparting coma aberration to the laser beam L, and in the first irradiation process, the control unit 6 may control the beam shape to be an inclined shape by controlling the coma aberration caused by the coma aberration pattern. Thus, by controlling the coma aberration imparted to the laser beam L, the inclined shape of the condensing spot C1 can be controlled. [Modification Example]

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

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

[0065] FIG. 14(a) shows the intensity distribution of the laser beam L on the entrance pupil plane 33a of the condenser lens 33. As shown in FIG. 14(a), by using such a modulation pattern PG1, the portion of the laser beam 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 condenser lens 33. As a result, as shown in FIGS. 14(b) and 15, the beam shape of the condensing spot C in the YZ plane can be made an inclined shape in which the whole is inclined in one direction with respect to the Z direction.

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

[0067] Note that in this case, the damage Dt caused by the leakage light Lt will be unevenly distributed on the first region R1 side. On the other hand, when making the damage Dt caused by the leakage light Lt unevenly distributed on the second region R2 side, in the modulation pattern PG1, the positions of the grating pattern Ga and the non-modulated region Ba may be interchanged. Also, each diagram of FIG. 15(b) shows the intensity distribution in the XY plane of the laser beam L at each position F1 to F7 in the Z direction shown in FIG. 15(a), and is the actual observation result by the camera.

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

[0069] The modulation pattern PG3 includes an unmodulated region Ba and a grating pattern Ga that are arranged in order in a direction away from the axis Ax on the negative side in the Y direction with respect to the axis AX, and also includes an unmodulated region Ba and a grating pattern Ga that are arranged in order in a direction away from the axis Ax on the positive side in the Y direction with respect to the axis Ax. In the modulation pattern PG3, the ratios of the unmodulated region Ba and the grating pattern Ga are made different between the positive side and the negative side in the Y direction with respect to the axis Ax (by relatively narrowing the unmodulated region Ba on the negative side in the Y direction), so that it is asymmetric with respect to the axis Ax.

[0070] The modulation pattern PG4 includes a grating pattern Ga in a part of the region on the negative side in the Y direction with respect to the axis Ax, similar to the modulation pattern PG2. In the modulation pattern PG4, further, with respect to the X direction, the region where the grating pattern Ga is provided is made a part. That is, in the modulation pattern PG4, in the region on the negative side in the Y direction with respect to the axis Ax, it includes an unmodulated region Ba, a grating pattern Ga, and an unmodulated region Ba arranged in order in the X direction. Here, the grating pattern Ga is arranged in a region including an axis Ay along the Y direction passing through the center Lc of the beam spot of the laser beam L in the X direction.

[0071] With any of the above modulation patterns PG2 to PG4, the beam shape of the condensing spot C can be made into an inclined shape that goes from the second region R2 to the first region R1 from the first surface 11a toward the second surface 11b at least on the first surface 11a side with respect to the center Ca. That is, in order to control the beam shape of the condensing spot C to go from the second region R2 to the first region R1 from the first surface 11a toward the second surface 11b at least on the first surface 11a side with respect to the center Ca, an asymmetric modulation pattern including a grating pattern Ga, such as the modulation patterns PG1 to PG4, or not limited to the modulation patterns PG1 to PG4, can be used. And by swapping the positions of the grating pattern Ga and the unmodulated region Ba, an inclined shape in the opposite direction can also be formed.

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

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

[0074] As shown in FIG. 18(a), by using such a modulation pattern PE, the beam shape of the condensing spot C in the YZ plane can be made an inclined shape that inclines to the negative side in the Y direction with respect to the Z direction on the side of the first surface 11a from the center Ca, that is, an inclined shape that goes from the second region R2 to the first region R1 as going from the first surface 11a to the second surface 11b. In particular, in this case, the beam shape of the condensing spot C in the YZ plane also inclines to the negative side in the Y direction with respect to the Z direction on the side opposite to the first surface 11a from the center Ca, that is, an inclined shape that goes from the first region R1 to the second region R2 as going from the first surface 11a to the second surface 11b, and becomes an arc shape as a whole.

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

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

[0077] In controlling the beam shape, when using the offset of the spherical aberration correction pattern, when using the coma aberration pattern, and when using the elliptical pattern, compared with the case of cutting a part of the laser beam using the diffraction grating pattern, processing with high energy becomes possible. Also, in these cases, it is effective when emphasizing the formation of cracks. When using the coma aberration pattern, in the case of multi-focus processing, it is possible to make the beam shape of only some of the condensing spots an inclined shape. Further, when using the axicon lens pattern, it is effective when emphasizing the formation of the modified region compared with other patterns.

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

[0079] Therefore, also in this case, a part of the first region R1 and the line A side of the second region have different structures from each other. And in this case, it is desirable to concentrate the damage Dt caused by the leakage light Lt on the first region R1 side rather than the second region R2 including the semiconductor device 11E. Therefore, also in this case, similar to the above-described embodiment, at least in step S101 and the first irradiation process, the control unit 6 modulates the laser beam L using the spatial light modulator 7, so that the beam shape of the condensing spot C1 in the YZ plane is inclined with respect to the Z direction at least on the first surface 11a side of the center Ca of the condensing spot C1.

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

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

[0082] Therefore, in this example, between a pair of second regions R2 each including a pair of adjacent semiconductor devices 11D, a pair of street regions Rs in which each of the pair of lines A is set are interposed, and one first region R1 (a region where the semiconductor device 11D is not formed) is provided between the pair of street regions Rs. Therefore, also in this case, when focusing on one line A, the structures of the first region R1 and a part of the second region R2 on the line A side are different. Also in this case, the second region R2 is an active region, and the first region R1 is a non-active region different from the active region. And in this example, it is desirable to unevenly distribute the damage Dt of the leakage light Lt to the first region R11 side where the semiconductor device 11D is not formed during the processing of any of the lines A.

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

[0084] On one hand, in step S101 and the first irradiation process, when processing the line A on the positive Y-direction side of the pair of lines A (that is, when the second region R2 is located on the positive Y-direction side as viewed from the processing progress direction FD (X-direction)), as shown in FIG. 23, the control unit 6 forms a condensing spot C12. In the condensing spot C12, on the side of the first surface 11a from its center Ca, as going from the first surface 11a to the second surface 11b (as going in the negative Z-direction), it is inclined so as to go from the second region R2 to the first region R1. Note that in the condensing spot C12, on the side of the second surface 11b from the center Ca, as going from the first surface 11a to the second surface 11b (as going in the negative Z-direction), it is inclined so as to go from the first region R1 to the second region R2. Thereby, the beam shape of the condensing spot C12 in the YZ plane is, as a whole, an arc shape convex on the negative Y-direction side. When forming the condensing spots C11 and C12, for example, it is possible to utilize coma aberration.

[0085] As described above, as shown in FIG. 24, in the processing of any of the pair of lines A, by unevenly distributing the damage Dt of the leakage light Lt to the side of the first region R1 where the semiconductor device 11D is not formed, it is possible to reduce the influence of the damage Dt of the leakage light Lt on the side of the second region R2 including the semiconductor device 11D. Note that as shown in FIG. 24(b), in the object 11 according to this modification example, a structure 11F such as a test chip or TEG may be formed between adjacent semiconductor devices 11D. In such a case, at least when the processing progress direction FD is set to the direction intersecting the direction (here, the Y-direction) in which the structure 11F is interposed between adjacent semiconductor devices 11D, two lines A are set so as to straddle the structure 11F, and the W-line processing is performed.

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

[0087] FIG. 25 is a diagram showing an object according to still another modified example. FIG. 25(a) is a plan view, and FIG. 25(b) is a cross-sectional view taken along line XXVb-XXVb of FIG. 25(a). In this example, a line A is set in an annular shape as viewed from the Z direction in the object 11. Further, the object 11 is joined to another wafer 11Z via a device layer 11Q. Trimming processing is performed on this object 11. In the trimming processing, by irradiating the laser beam L along the line A, a plurality of modified regions 12a and 12b arranged in the Z direction, a crack (oblique crack 13a) extending from the modified region 12a, and a crack (vertical crack 13b) extending from the modified region 12b are formed. Thereby, the annular region outside the line A is removed from the object 11.

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

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

[0090] Here, the second region R2 includes the active area inside the device layer 11Q. The first region R1 is a region where the device layer 11Q is not formed (a region outside the device layer 11Q). That is, also here, the second region R2 is the active region, and the first region R1 is a non-active region different from the active region. The active region here is the region inside the device layer 11Q. The non-active region here is the region outside the device layer 11Q. A third region R3 including the non-active area at the outer edge of the device layer 11Q is interposed between the first region R1 and the second region R2. At least the line A for forming the reformed region 12a is located in this third region R3 as viewed from the Z direction. Therefore, also in this example, the structures of a part of the first region R1 and the second region R2 on the line A side are different. And in this example, the damage Dt of the leakage light Lt is unevenly distributed on the first region R1 side opposite to the second region R2 which is the active area of the device layer 11Q.

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

[0092] Furthermore, here, in process S102 and the second irradiation process, the laser beam L2 is shaped such that the beam shape of the condensing spot C2 has an inclined shape inclined in the shifting direction (here, the negative Y direction) at least on the first surface 11a side from the center of the condensing spot C2. As an example, the beam shape of the condensing spot C2 can be the same as that of the condensing spot C1. Thereby, an oblique crack 13a is formed so as to be inclined in the shifting direction of the condensing spot C2 in the YZ plane. The oblique crack 13a is formed to be inclined outward of the object 11 as it goes from the first surface 11a to the second surface 11b. Thereby, it is suppressed that a crack extends vertically from the modified region 12 to the second surface 11b side and reaches the device layer 11Q or another wafer 11Z.

[0093] Note that when forming those other than the modified region 12b on the most modified region 12a side among the modified regions 12b, the beam shape of the condensing spot C2 can be set to a non-inclined shape along the Z direction so that a vertical crack 13b extending along the Z direction is formed.

[0094] As described above, also for the trimming process of the object 11, by controlling the beam shape of the condensing spot C1 in process S101 and the first irradiation process, it is possible to reduce the influence of the damage Dt of the leakage light Lt, and to form the oblique crack 13a toward the second surface 11b side to suppress the unintentional progression of the crack to the device layer 11Q or another wafer 11Z.

[0095] In the above example, the case where the formation of the diagonal crack 13a during trimming and the reduction of the influence of the damage Dt of the missing light Lt are used in combination has been described. However, even in cases other than trimming, there is a requirement to form the diagonal crack 13a. Therefore, in any case where the diagonal crack 13a is formed, the beam shape of the condensing spot C1 can be controlled in order to reduce the influence of the damage Dt of the missing light Lt.

Explanation of reference numerals

[0096] 1... Laser processing apparatus, 2... Stage (support part), 4, 5... Driving part (moving part), 6... Control part, 7... Spatial light modulator, 11... Object, 11a... First surface, 11b... Second surface, 31... Light source, 33... Condensing lens, A... Line, C, C1, C2... Condensing spots, R1... First region, R2... Second region, W... Wiring part.

Claims

1. a support part for supporting an object; a light source for outputting laser light; a spatial light modulator for modulating and outputting the laser light output from the light source according to a modulation pattern; a condenser lens for condensing the laser light output from the spatial light modulator toward the object and forming a condensed spot of the laser light on the object; a moving part for relatively moving the condensed spot with respect to the object; a control part for controlling at least the light source, the spatial light modulator, and the moving part; comprising; the object includes a first surface that is an incident surface of the laser light, a second surface opposite to the first surface, and a first region and a second region arranged on the second surface, and a line is set for relatively moving the condensed spot so as to pass between the first region and the second region, at least a part of at least the line side of the first region and the second region has different structures from each other; the control part controls the light source, the spatial light modulator, and the moving part to irradiate the object with the laser light while relatively moving the condensed spot along the line in a state where the condensed spot is positioned at a first Z position on the second surface side of the first surface with respect to the Z direction intersecting the first surface and the second surface; the line is set in an annular shape when viewed from the Z direction; in the first irradiation process, the control part controls the modulation pattern to be displayed on the spatial light modulator so that the beam shape of the condensed spot in the YZ plane including the Y direction and the Z direction intersecting the line and the Z direction is inclined with respect to the Z direction so as to face outward of the object from the first surface toward the second surface at least on the first surface side of the center of the condensed spot; a laser processing apparatus.

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

3. the control part controls the light source, the spatial light modulator, and the moving part to execute a second irradiation process of irradiating the object with the laser light while relatively moving the condensed spot along the line in a state where the condensed spot is positioned at a second Z position farther from the second surface than the first Z position with respect to the Z direction; In the second irradiation process, the control unit controls the modulation pattern displayed on the spatial light modulator so that the beam shape of the condensing spot in the YZ plane is an inclined shape inclined with respect to the Z direction so as to face outward from the first surface toward the second surface at least on the first surface side of the center of the condensing spot. The laser processing apparatus according to claim 1 or 2.

4. The control unit executes a second irradiation process of irradiating the object with the laser light while relatively moving the condensing spot along the line in a state where the condensing spot is positioned at a second Z position farther from the second surface than the first Z position in the Z direction by controlling the light source, the spatial light modulator, and the moving unit. In the second irradiation process, the control unit makes the beam shape of the condensing spot in the YZ plane a non-inclined shape along the Z direction by controlling the spatial light modulator. The laser processing apparatus according to claim 1 or 2.

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

Images