Laser processing apparatus and laser processing method

Abstract

A laser processing device for forming a modified region by irradiating an object with laser light, the laser processing device being provided with: a support unit for supporting the object; an irradiation unit for irradiating the laser light to the object supported by the support unit; a displacement information acquisition unit that irradiates a laser beam for measurement onto a laser beam incident surface of the object supported by the support unit, and acquires first displacement information corresponding to the displacement of the incident surface by receiving reflected light of the laser beam for measurement on the incident surface; a movement mechanism for moving the focal point of the laser light and the irradiation region of the measurement laser light relative to the object; and a control unit for scanning the laser light and the measurement laser light on the object by controlling the movement mechanism.

Description

Technical Field

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

[0002] Patent Document 1 (Japanese Patent Application Publication No. 2009-113068) describes a laser processing device. This laser processing device includes a worktable that supports an object to be processed, a laser light source that emits laser light through a lens, an AF (Auto Focus) unit, and a drive unit. The AF unit emits AF laser light and receives reflected light from the AF laser light, thereby obtaining a displacement signal related to the displacement of a reflective surface. Furthermore, the AF unit inputs a voltage signal to the drive unit such that the displacement signal becomes a reference displacement signal, thereby driving the lens along the optical axis. This drives the lens (i.e., the focal point of the laser light formed by the lens) to track the displacement of the reflective surface. Summary of the Invention

[0003] However, in the aforementioned technical field, when the laser incident surface of an object includes two-dimensionally arranged device regions and street regions passing between adjacent device regions, laser light may be scanned across the street regions to form a modified region on the object. In such cases, the aforementioned AF laser is also scanned across the street regions to obtain the displacement of the street regions. This allows the laser light to be scanned while the laser's focal point tracks the displacement of the street regions.

[0004] At this time, for example, if the spot diameter on the incident surface of the AF laser is larger than the width of the cutting path area, a portion of the AF laser will also irradiate the device area. Alternatively, even if the spot diameter on the incident surface of the AF laser is smaller than the width of the cutting path area, for example, when scanning the AF laser closer to the device area than the center of the cutting path area, a portion of the AF laser will also irradiate the device area. In the case where the AF laser also irradiates the device area like this, the displacement signal obtained based on the reflected light of the AF laser contains a lot of noise caused by the influence of the device area (such as occlusion and reflection). Therefore, the displacement signal becomes a waveform different from the actual displacement of the incident surface in the cutting path area, and the accuracy of tracking the laser focal point based on the displacement signal may be reduced.

[0005] Therefore, an object of the present disclosure is to provide a laser processing apparatus and a laser processing method capable of suppressing a decrease in the tracking accuracy of a laser beam.

[0006] The laser processing device disclosed in the present invention is [1] "a laser processing device, which is a laser processing device for irradiating a target with a laser to form a modified area, comprising: a support portion for supporting the target; an irradiation portion for irradiating the target supported by the support portion with the laser; a displacement information acquisition portion for irradiating a measuring laser on an incident surface of the laser of the target supported by the support portion, and receiving reflected light of the measuring laser on the incident surface, thereby acquiring first displacement information corresponding to the displacement of the incident surface; a moving mechanism for causing a focal point of the laser in the target and an irradiation area of ​​the measuring laser to move relative to the target; and a control portion for controlling the moving mechanism to scan the target with the laser and the measuring laser on the target, wherein, when viewed from a direction intersecting the incident surface, the incident surface of the target includes: a plurality of device areas arranged along a first direction and a second direction intersecting each other; a plurality of first cutting road areas extending along the first direction. and a plurality of second cutting road areas extending along the second direction and being areas between the device areas adjacent to each other along the first direction, the control unit implements the following processing: a first acquisition processing, wherein the displacement information acquisition unit acquires the first displacement information in the first cutting road area by scanning the measuring laser on the first cutting road area; a second acquisition processing, wherein a plurality of intersection point information corresponding to the intersection points of the first cutting road area and the second cutting road area are extracted from the first displacement information acquired by the first acquisition processing, and the extracted plurality of intersection point information are interpolated in the first direction, thereby acquiring second displacement information corresponding to the displacement of the first cutting road area; and a first processing processing, wherein the position of the focal point in the direction intersecting the incident surface is adjusted based on the second displacement information, while the laser is scanned on the first cutting road area, thereby forming the modified area on the object.

[0007] The laser processing method disclosed herein is [8] "a laser processing method, which is a laser processing method for forming a modified region by irradiating a laser on an object, comprising: a first acquisition step, wherein a measuring laser is irradiated on an incident surface of the laser on the object, and reflected light of the measuring laser on the incident surface is received, thereby obtaining first displacement information corresponding to the displacement of the incident surface; a second acquisition step, wherein second displacement information is obtained based on the first displacement information; and a processing step, wherein the modified region is formed on the object by scanning the laser on the object. In the laser processing method, when viewed from a direction intersecting the incident surface, the incident surface of the object includes: a plurality of device regions arranged along first and second directions intersecting each other; a plurality of first cutting road regions extending along the first direction and being regions between the device regions adjacent to each other along the second direction. ; and a plurality of second cutting road areas, which extend along the second direction and are areas between the device areas adjacent along the first direction, and: in the first acquisition process, the first displacement information in the first cutting road area is acquired by scanning the measuring laser on the first cutting road area; in the second acquisition process, a plurality of intersection point information corresponding to the intersection points of the first cutting road area and the second cutting road area are extracted from the first displacement information acquired by the first acquisition process, and the extracted plurality of intersection point information are interpolated in the first direction, thereby acquiring second displacement information corresponding to the displacement of the first cutting road area; in the processing process, the position of the focal point in the direction intersecting the incident surface is adjusted based on the second displacement information, while the laser is scanned on the first cutting road area, thereby forming the modified area on the object. "

[0008] In this laser processing device and method, a measuring laser is irradiated onto the laser incident surface of an object, and reflected light from the measuring laser on the incident surface is received, thereby acquiring first displacement information corresponding to the displacement of the incident surface. Based on this first displacement information, the laser can be scanned while the laser's focal point tracks the displacement of the incident surface. Specifically, the object includes, on the laser incident surface, a plurality of device regions arranged along intersecting first and second directions; a plurality of first scribe regions extending along the first direction as regions between the device regions; and a plurality of second scribe regions extending along the second direction as regions between the device regions. Furthermore, when acquiring the first displacement information, the measuring laser is scanned across the first scribe regions. Consequently, the measurement laser may also irradiate the device regions, potentially increasing noise in the first displacement information.

[0009] In this regard, in this laser processing apparatus and method, multiple intersection point information corresponding to the intersections of the first and second street regions is extracted from the first displacement information. This extracted intersection point information is interpolated to obtain second displacement information corresponding to the displacement of the first street region. The laser is then scanned across the first street region while adjusting the position of the focal point in a direction intersecting the incident surface based on this second displacement information, thereby forming a modified region on the object.

[0010] At the intersection of the first cutting path area and the second cutting path area, there is no device area in the width direction of the first cutting path area, that is, the second direction (that is, the second cutting path area extends in the second direction), so the measuring laser is not easy to irradiate the device area compared with the area outside the intersection of the first cutting path area. Therefore, in the intersection information corresponding to the intersection in the first displacement information, the noise caused by the measuring laser irradiating the device area is relatively small. Therefore, in the second displacement information obtained by interpolating the multiple intersection information in the first displacement information in the first direction, the influence of noise is small, and the actual displacement of the first cutting path area can be more accurately reflected. Thus, when a modified area is formed on the object, by utilizing the second displacement information, the tracking accuracy of the focal point of the laser in the direction intersecting the incident surface can be suppressed.

[0011] The laser processing device disclosed in the present invention may also be, [2] "a laser processing device as described in [1] above, wherein the width of the first cutting path area in the second direction is narrower than the size of the spot of the measuring laser on the incident surface". In this case, as described above, a portion of the measuring laser is easily irradiated to the device area. Therefore, in the area other than the intersection of the first cutting path area and the second cutting path area, the influence of the noise of the first displacement information becomes greater. Therefore, it is more advantageous to use the second displacement information obtained by interpolating the intersection information with relatively less noise in the first displacement information.

[0012] The laser processing device disclosed in the present invention may also be, [3] "a laser processing device as described in [1] or [2] above, wherein, in the first acquisition process and the first processing process, the control unit scans the measuring laser and the laser at a position closer to one side in the second direction than the center of the first cutting path area in the second direction". In this case, as described above, a part of the measuring laser is also likely to irradiate the device area. Therefore, in the area other than the intersection of the first cutting path area and the second cutting path area, the influence of the noise of the first displacement information becomes greater. Therefore, it is more advantageous to use the second displacement information obtained by interpolating the intersection information with relatively less noise in the first displacement information.

[0013] The laser processing device disclosed in the present invention may also be, [4] "a laser processing device as described in any one of [1] to [3] above, wherein, in the second acquisition process, the control unit estimates the position of the intersection point with the second cutting path area in the first cutting path area based on the concave-convex shape of the waveform of the first displacement information, and extracts the intersection point information from the first displacement information based on the estimated position". In this case, for example, it is not necessary to calculate the position of the intersection point with the second cutting path area in the first cutting path area based on the pattern of the incident surface of the object.

[0014] The laser processing device disclosed herein may also be, [5] "the laser processing device as described in [4] above, wherein, in the second acquisition process, the control unit estimates the protruding portion of the concave-convex shape of the waveform of the first displacement information as the position of the intersection with the second cutting path area in the first cutting path area." In this case, the intersection information can be more reliably extracted from the first displacement information based on the concave-convex shape of the waveform of the first displacement information.

[0015] The laser processing device disclosed in the present invention may also be, [6] "a laser processing device as described in any one of [1] to [3] above, wherein, in the second acquisition process, the control unit calculates the position of the intersection of the first cutting path area with the second cutting path area based on pattern information of the pattern including the first cutting path area and the second cutting path area on the incident surface, and extracts the intersection information from the first displacement information based on the calculated position". In this case, when extracting the intersection information from the first displacement information, it is not necessary to estimate the position of the intersection of the first cutting path area with the second cutting path area. Thus, the intersection information can be extracted more reliably and in a short time.

[0016] Here, after the measurement laser and laser scanning are completed for all first cutting street areas, multiple first displacement information corresponding to the displacements of each of the first cutting street areas can be obtained. The multiple first displacement information respectively includes intersection information corresponding to the intersections of the first cutting street area and the second cutting street area. Therefore, when the laser is scanned for the second cutting street area, the new displacement information obtained by interpolating the intersection information in the second direction can also be considered. In this case, it is not necessary to scan the second cutting street area with the measurement laser when the laser is scanned for the second cutting street area, which is advantageous in this regard.

[0017] On the other hand, after laser scanning of the first street area completes and a modified area is formed on the object, deformation, such as warping, may occur in the object. In this case, the interpolation of the intersection information contained in the first displacement information obtained by operating the measuring laser on the first street area may not reflect the actual displacement of the second street area, including deformation of the object caused by the formation of the modified area. To address this issue, the laser processing apparatus disclosed herein may have the following configuration.

[0018] That is, the laser processing device disclosed in the present invention may also be, [7] "a laser processing device as described in any one of [1] to [6] above, wherein the control unit implements the following processing: a third acquisition processing, wherein the displacement information acquisition unit acquires the first displacement information in the second cutting road area by scanning the measuring laser on the second cutting road area; a fourth acquisition processing, wherein a plurality of intersection point information corresponding to the intersection of the second cutting road area and the first cutting road area is extracted from the first displacement information acquired by the third acquisition processing, and the extracted plurality of intersection point information is interpolated in the second direction, thereby acquiring third displacement information corresponding to the displacement of the second cutting road area; and a second processing processing, wherein the position of the focal point in the direction intersecting the incident surface is adjusted based on the third displacement information while scanning the laser on the second cutting road area, thereby forming the modified area on the object".

[0019] In this case, when the second street area is scanned with a laser, similar to the first street area, the measuring laser is scanned across the second street area to obtain first displacement information corresponding to the displacement of the second street area. Intersection point information is then extracted from this first displacement information, and the extracted intersection point information is interpolated in the second direction to obtain third displacement information that more accurately reflects the actual displacement of the second street area. This allows for more reliable suppression of any reduction in tracking accuracy of the laser's focal point in directions intersecting the incident surface when the second street area is scanned with a laser.

[0020] Effects of the Invention

[0021] According to the present disclosure, it is possible to provide a laser processing apparatus and a laser processing method capable of suppressing a decrease in tracking accuracy of a laser beam. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a perspective view showing a laser processing apparatus according to an embodiment.

[0023] Figure 2This is a perspective view of an object mounted on a support table of a laser processing apparatus according to an embodiment.

[0024] Figure 3 It is along Figure 1 Cross-sectional view of the XY plane.

[0025] Figure 4 It is a perspective view showing a part of a laser output unit and a laser focusing unit of a laser processing device according to an embodiment.

[0026] Figure 5 It is along Figure 1 Cross-sectional view of the XY plane.

[0027] Figure 6 It is along Figure 5 Cross-sectional view along line VI-VI.

[0028] Figure 7 It is along Figure 6 Cross-sectional view along line VII-VII.

[0029] Figure 8 It is a front view showing a schematic configuration of a heteroaxial distance measuring sensor according to the embodiment.

[0030] Figure 9 This is a diagram showing a state in which the markings on the reticle are in focus in an image of the laser incident surface captured by the observation camera of the embodiment.

[0031] Figure 10 It will Figure 2 A schematic diagram showing an enlarged portion of the object shown.

[0032] Figure 11 : is a graph showing an example of first displacement information obtained by the heteroaxial distance measuring sensor.

[0033] Figure 12 Flowchart showing the laser processing method according to this embodiment.

[0034] Figure 13 Yes Figure 12 A diagram showing one process step of the laser processing method.

[0035] Figure 14 Yes Figure 12 A diagram showing one process step of the laser processing method.

[0036] Figure 15 Yes Figure 12 A diagram showing one process step of the laser processing method.

[0037] Figure 16 : is a graph showing an example of the first displacement information, the intersection information, and the second displacement information.

[0038] Figure 17 This is a graph showing another example of the first displacement information.

[0039] Figure 18 This is a graph showing another example of the first displacement information.

[0040] Figure 19 Yes Figure 12 A diagram showing one process step of the laser processing method.

[0041] Figure 20 This is a diagram showing one step of laser processing of the second scribe line region.

[0042] Figure 21 : is a graph showing an example of the first displacement information and the third displacement information.

[0043] Figure 22 It is a diagram showing a state of laser processing according to a modified example.

[0044] Figure 23 It is a figure which shows the object of a modification example. DETAILED DESCRIPTION

[0045] Below, a laser processing apparatus and a laser processing method according to one embodiment are described with reference to the accompanying drawings. In the various figures, identical or corresponding elements are sometimes denoted by the same reference numerals, and duplicate descriptions are omitted. Furthermore, in the various figures, an orthogonal coordinate system including an X-axis, a Y-axis perpendicular to the X-axis, and a Z-axis perpendicular to the X-axis and Y-axis is sometimes shown. For example, the X-axis and Y-axis directions are horizontal, and the Z-axis direction is vertical.

[0046] like Figure 1 As shown, in the laser processing device 200, a modified region is formed on the object 1 by irradiating the object 1 with laser light. As the object 1, a plate-shaped member (e.g., substrate, wafer, etc.) including a semiconductor substrate formed of a semiconductor material, a piezoelectric substrate formed of a piezoelectric material, etc. is used. Figure 2 As shown, a line to cut 5 is defined within object 1 for cutting object 1. Line to cut 5 is a virtual line extending linearly. To form a modified region within object 1, a laser is moved relative to line to cut 5 while aligning the focal point (at least a portion of the focal region) with the interior of object 1. Consequently, a modified region is formed within object 1 along line to cut 5.

[0047] The predetermined cutting line 5 is not limited to a straight line, but can be a curved line, a three-dimensional shape composed of a combination of these, or a shape specified by coordinates. The predetermined cutting line 5 is not limited to a virtual line, but can be a line actually drawn on the front of the object 1. The modified area can be formed continuously or intermittently. The modified area can be in the form of a column or a point. In short, the modified area can be formed at least inside the object 1. In addition, cracks are sometimes formed starting from the modified area, and the cracks and the modified area can be exposed on the outer surface (front, back or peripheral surface) of the object 1. The laser incident surface when forming the modified area is not limited to the front of the object 1, but can also be the back of the object 1.

[0048] A modified region refers to a region where the density, refractive index, mechanical strength, or other physical properties are different from those of the surrounding region. Examples of modified regions include melt-treated regions (meaning at least one of a region that is temporarily melted and then solidified, a region in a molten state, and a region in a state from melting to resolidification), crack regions, dielectric breakdown regions, and refractive index change regions. There are also regions where these regions exist in a mixed state. Modified regions include regions where the density of the modified region in the material of object 1 has changed compared to the density of the non-modified region, and regions where lattice defects have been formed. In the case where the material of object 1 is single crystal silicon, the modified region can also be said to be a high dislocation density region.

[0049] For the melt-processed region, the refractive index change region, the region where the density of the modified region has changed compared to the density of the non-modified region, and the region where lattice defects are formed, there is a case where cracks (cracks, microcracks) are further included in the interior of these regions and at the interface between the modified region and the non-modified region. The included cracks may be formed over the entire surface of the modified region, only in a part, or in multiple parts. Object 1 includes a substrate composed of a crystalline material having a crystal structure. For example, object 1 includes a substrate formed of at least any one of gallium nitride (GaN), silicon (Si), silicon carbide (SiC), LiTaO3, and sapphire (Al2O3). In other words, object 1 includes, for example, a gallium nitride substrate, a silicon substrate, a SiC substrate, a LiTaO3 substrate, or a sapphire substrate. The crystal material may be any one of an anisotropic crystal and an isotropic crystal. In addition, object 1 may include a substrate composed of an amorphous material having an amorphous structure (amorphous structure), for example, a glass substrate.

[0050] In an embodiment, a modified area can be formed by forming a plurality of modified points (processing marks) along the predetermined cutting line 5. In this case, a plurality of modified points are concentrated to form a modified area. A modified point refers to a modified portion formed by irradiation of one pulse of a pulsed laser (i.e., one pulse of laser irradiation: laser shot). As modified points, crack points, melting processing points or refractive index change points, or modified points in which at least one of them is mixed, etc. can be listed. Regarding the modified points, their size and the length of the cracks generated can be appropriately controlled while considering the required cutting accuracy, the required flatness of the cut surface, the thickness, type, crystal orientation, etc. of the object 1. In an embodiment, the modified points can be formed into a modified area along the predetermined cutting line 5.

[0051] like Figure 1 As shown, the laser processing apparatus 200 includes an apparatus frame 210, a first moving mechanism (moving mechanism) 220, a support table (support unit) 230, and a second moving mechanism (moving mechanism) 240. Furthermore, the laser processing apparatus 200 includes a laser output unit 300, a laser focusing unit (irradiation unit) 400, and a control unit 500.

[0052] The first moving mechanism 220 is mounted on the device frame 210. The first moving mechanism 220 includes a first rail unit 221, a second rail unit 222, and a movable base 223. The first rail unit 221 is mounted on the device frame 210. The first rail unit 221 is provided with a pair of rails 221a and 221b extending along the Y-axis direction. The second rail unit 222 is mounted on the pair of rails 221a and 221b of the first rail unit 221 so as to be movable along the Y-axis direction. The second rail unit 222 is provided with a pair of rails 222a and 222b extending along the X-axis direction. The movable base 223 is mounted on the pair of rails 222a and 222b of the second rail unit 222 so as to be movable along the X-axis direction. The movable base 223 is rotatable about an axis parallel to the Z-axis direction.

[0053] The support table 230 is mounted on the movable base 223. The support table 230 supports the object 1. Figure 2In the example shown, object 1 is an object having a plurality of functional elements (e.g., light-receiving elements such as photodiodes, light-emitting elements such as laser diodes, or circuit elements formed as circuits) formed in a matrix on the front side of a substrate made of a semiconductor material such as silicon. When object 1 is supported on support table 230, for example, back surface 1b of object 1, opposite to front surface 1a (the surface facing the plurality of functional elements), is attached to film 12 extending over annular frame 11. Support table 230 holds frame 11 with a clamp and supports object 1 by adsorbing film 12 using a vacuum chuck. On support table 230, a plurality of parallel lines to cut 5a and a plurality of parallel lines to cut 5b are arranged in a grid pattern on object 1 so as to pass between adjacent functional elements.

[0054] like Figure 1 As shown, the support table 230 is movable along the Y-axis direction by the second rail unit 222 operating in the first moving mechanism 220. Furthermore, the support table 230 is movable along the X-axis direction by the movable base 223 operating in the first moving mechanism 220. Furthermore, the support table 230 is rotated about an axis parallel to the Z-axis direction by the movable base 223 operating in the first moving mechanism 220. Thus, the support table 230 is mounted on the device frame 210 so as to be movable along the X-axis and Y-axis directions and rotatable about an axis parallel to the Z-axis direction.

[0055] The laser output unit 300 is mounted on the device frame 210. The laser focusing unit 400 is mounted on the device frame 210 via the second moving mechanism 240. The laser focusing unit 400 is moved along the Z-axis direction (the optical axis direction of the focusing lens unit 430, described later) by the operation of the second moving mechanism 240. Thus, the laser focusing unit 400 is mounted on the device frame 210 so as to be movable along the Z-axis direction relative to the laser output unit 300.

[0056] The control unit 500 is composed of a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc. The control unit 500 controls the operation of each unit of the laser processing apparatus 200. Details of the processing performed by the control unit 500 will be described later.

[0057] In the laser processing apparatus 200, for example, as described below, a modified region is formed within the object 1 along the respective planned cutting lines 5a and 5b. First, the object 1 is supported on a support table 230 so that the front surface 1a of the object 1 serves as the incident surface for the laser beam. Each planned cutting line 5a of the object 1 is aligned parallel to the X-axis. Alignment (so-called height setting) is performed, namely, the Z-axis position of the condensing lens unit 430 (described later) relative to the incident surface is aligned with a reference position. The laser focusing unit 400 is moved in the Z-axis direction by the second moving mechanism 240 so that the focal point of the laser beam L is located within the object 1 at a predetermined distance from the incident surface. While maintaining a constant distance between the incident surface and the focal point of the laser beam L, the focal point of the laser beam L is relatively moved along each planned cutting line 5a. Thus, a modified region is formed within the object 1 along each planned cutting line 5a. The incident surface is not limited to the front surface 1a; the rear surface 1b may also be used.

[0058] When the formation of the modified region along each planned cutting line 5a is completed, the support table 230 is rotated by the first moving mechanism 220 so that each planned cutting line 5b of the object 1 is aligned with a direction parallel to the X-axis. The height is set. The laser focusing unit 400 is moved by the second moving mechanism 240 so that the focal point of the laser light L is located within the object 1 at a predetermined distance from the laser incident surface. While maintaining the distance between the laser incident surface and the focal point of the laser light L constant, the focal point of the laser light L is relatively moved along each planned cutting line 5b. Thus, a modified region is formed within the object 1 along each planned cutting line 5b.

[0059] Thus, in the laser processing apparatus 200, the direction parallel to the X-axis direction serves as the processing direction (the scanning direction of the laser light L). Furthermore, the relative movement of the focal point of the laser light L along each planned cutting line 5a and the relative movement of the focal point of the laser light L along each planned cutting line 5b is achieved by moving the support table 230 in the X-axis direction using the first moving mechanism 220. Furthermore, the relative movement of the focal point of the laser light L between each planned cutting line 5a and the relative movement of the focal point of the laser light L between each planned cutting line 5b is achieved by moving the support table 230 in the Y-axis direction using the first moving mechanism 220.

[0060] like Figure 3 As shown, the laser output unit 300 includes a mounting base 301, a cover 302, and a plurality of reflective mirrors 303 and 304. Furthermore, the laser output unit 300 includes a laser oscillator (laser light source) 310, a shutter 320, a λ / 2 wave plate unit (output adjustment unit, polarization direction adjustment unit) 330, a polarizing plate unit (output adjustment unit, polarization direction adjustment unit) 340, a beam expander (laser parallelization unit) 350, and a reflective mirror unit 360.

[0061] The mounting base 301 supports a plurality of reflecting mirrors 303, 304, a laser oscillator 310, a shutter 320, a λ / 2 wave plate unit 330, a polarizing plate unit 340, a beam expander 350, and a reflecting mirror unit 360. The plurality of reflecting mirrors 303, 304, the laser oscillator 310, the shutter 320, the λ / 2 wave plate unit 330, the polarizing plate unit 340, the beam expander 350, and the reflecting mirror unit 360 are mounted on the main surface 301a of the mounting base 301. The mounting base 301 is a plate-shaped member that can be mounted relative to the device frame 210 (see FIG. Figure 1 The laser output unit 300 is mounted on the device frame 210 via the mounting base 301. That is, the laser output unit 300 is detachable relative to the device frame 210.

[0062] The cover 302 covers the plurality of mirrors 303 and 304, the laser oscillator 310, the shutter 320, the λ / 2 wave plate unit 330, the polarizing plate unit 340, the beam expander 350, and the mirror unit 360 on the main surface 301a of the mounting base 301. The cover 302 is attachable to and detachable from the mounting base 301.

[0063] The laser oscillator 310 pulses linearly polarized laser light L along the X-axis direction. The wavelength of the laser light L emitted from the laser oscillator 310 is included in any one of the wavelength bands of 500 to 550 nm, 1000 to 1150 nm, or 1300 to 1400 nm. The laser light L in the wavelength band of 500 to 550 nm is suitable for internal absorption laser processing of substrates made of sapphire, for example. The laser light L in the wavelength bands of 1000 to 1150 nm and 1300 to 1400 nm is suitable for internal absorption laser processing of substrates made of silicon, for example. The polarization direction of the laser light L emitted from the laser oscillator 310 is, for example, parallel to the Y-axis direction. The laser light L emitted from the laser oscillator 310 is reflected by the reflector 303 and enters the shutter 320 along the Y-axis direction.

[0064] In the laser oscillator 310, the output of the laser L is switched on / off as described below. In the case where the laser oscillator 310 is composed of a solid-state laser, the output of the laser L is switched on / off at high speed by switching on / off the Q switch (AOM (acousto-optic modulator), EOM (electro-optic modulator), etc.) provided in the resonator. In the case where the laser oscillator 310 is composed of a fiber laser, the output of the laser L is switched on / off at high speed by switching on / off the output of the semiconductor laser constituting the seed laser and the amplification (excitation) laser. In the case where the laser oscillator 310 uses an external modulation element, the output of the laser L is switched on / off at high speed by switching on / off the external modulation element (AOM, EOM, etc.) provided outside the resonator.

[0065] Shutter 320 mechanically opens and closes the optical path of laser light L. As described above, the on / off switching of the output of laser light L from laser output section 300 is implemented by the on / off switching of the output of laser light L from laser oscillator 310. However, by providing shutter 320, it is possible to prevent, for example, unintended emission of laser light L from laser output section 300. After passing through shutter 320, laser light L is reflected by reflective mirror 304 and sequentially enters λ / 2 wave plate unit 330 and polarizing plate unit 340 along the X-axis direction.

[0066] The λ / 2 wave plate unit 330 and the polarizing plate unit 340 function as an output adjustment unit that adjusts the output (light intensity) of the laser light L. Furthermore, the λ / 2 wave plate unit 330 and the polarizing plate unit 340 function as a polarization direction adjustment unit that adjusts the polarization direction of the laser light L. These details will be described later. After sequentially passing through the λ / 2 wave plate unit 330 and the polarizing plate unit 340, the laser light L enters the beam expander 350 along the X-axis direction.

[0067] The beam expander 350 collimates the laser light L while adjusting the diameter of the laser light L. The laser light L having passed through the beam expander 350 enters the mirror unit 360 along the X-axis direction.

[0068] The reflector unit 360 has a support base 361 and a plurality of reflectors 362 and 363. The support base 361 supports the plurality of reflectors 362 and 363. The support base 361 is mounted on the mounting base 301 in such a manner that the position thereof can be adjusted along the X-axis direction and the Y-axis direction. The reflector 362 reflects the laser light L after passing through the beam expander 350 in the Y-axis direction. The reflector 362 is mounted on the support base 361 in such a manner that the angle of the reflector surface thereof can be adjusted, for example, around an axis parallel to the Z-axis. The reflector 363 reflects the laser light L reflected by the reflector 362 in the Z-axis direction. The reflector 363 is mounted on the support base 361 in such a manner that the angle of the reflector surface thereof can be adjusted, for example, around an axis parallel to the X-axis and the position thereof can be adjusted along the Y-axis direction. The laser light L reflected by the reflector 363 passes through the opening 361a formed in the support base 361 and is incident on the laser focusing portion 400 (see Figure 1). That is, the emission direction of the laser light L from the laser output unit 300 is aligned with the movement direction of the laser focusing unit 400. As described above, each of the reflectors 362 and 363 has a mechanism for adjusting the angle of the reflective surface. In the reflector unit 360, by adjusting the position of the support base 361 relative to the mounting base 301, adjusting the position of the reflector 363 relative to the support base 361, and adjusting the angle of the reflective surface of each of the reflectors 362 and 363, the position and angle of the optical axis of the laser light L emitted from the laser output unit 300 are aligned with those of the laser focusing unit 400. In other words, the multiple reflectors 362 and 363 are configured to adjust the optical axis of the laser light L emitted from the laser output unit 300.

[0069] like Figure 4 As shown, the laser focusing unit 400 has a housing 401. The housing 401 is in the shape of a rectangular parallelepiped with the Y-axis direction as the long side direction. The second moving mechanism 240 (see Figure 5 and Figure 7 A cylindrical light incident portion 401a is provided in the housing 401 so as to face the opening 361a of the reflector unit 360 in the Z-axis direction. The light incident portion 401a allows the laser light L emitted from the laser output unit 300 to enter the housing 401. The reflector unit 360 and the light incident portion 401a are spaced apart from each other at a distance sufficient to prevent contact when the laser focusing unit 400 is moved in the Z-axis direction by the second moving mechanism 240.

[0070] like Figure 5 and Figure 6 As shown, the laser focusing unit 400 includes a reflective mirror 402 and a dichroic mirror 403. Furthermore, the laser focusing unit 400 includes a reflective spatial light modulator (SLM) 410, a 4f lens unit 420, a focusing lens unit 430, a drive mechanism 440, and a pair of off-axis distance measurement sensors (displacement information acquisition unit) 450. The laser focusing unit 400 irradiates the object 1 with laser light L via the focusing lens unit 430.

[0071] The reflector 402 is mounted on the bottom surface 401b of the housing 401 so as to oppose the light incident portion 401a in the Z-axis direction. The reflector 402 reflects the laser light L incident on the housing 401 via the light incident portion 401a in a direction parallel to the XY plane. The laser light L, collimated by the beam expander 350 of the laser output unit 300, enters the reflector 402 along the Z-axis direction. In other words, the laser light L enters the reflector 402 as parallel light along the Z-axis direction. Therefore, even if the laser focusing unit 400 is moved along the Z-axis direction by the second moving mechanism 240, the state of the laser light L incident on the reflector 402 along the Z-axis direction can be maintained constant. The laser light L reflected by the reflector 402 enters the reflective spatial light modulator 410.

[0072] The reflective spatial light modulator 410 is mounted at the end 401c of the housing 401 in the Y-axis direction, with its reflective surface 410a facing the interior of the housing 401. The reflective spatial light modulator 410 is, for example, a reflective liquid crystal (LCOS: Liquid Crystal on Silicon) spatial light modulator (SLM), which modulates the laser light L while reflecting it in the Y-axis direction. The laser light L modulated and reflected by the reflective spatial light modulator 410 enters the 4f lens unit 420 along the Y-axis direction. Here, in a plane parallel to the XY plane, the angle α formed between the optical axis of the laser light L entering the reflective spatial light modulator 410 and the optical axis of the laser light L emitted from the reflective spatial light modulator 410 is an acute angle (e.g., 10 to 60°). In other words, the laser light L is reflected at an acute angle along the XY plane by the reflective spatial light modulator 410. This is to suppress the incident angle and reflection angle of the laser light L to suppress a decrease in diffraction efficiency and to fully demonstrate the performance of the reflective spatial light modulator 410 .

[0073] The 4f lens unit 420 includes a holder 421, a lens 422 on the reflective spatial light modulator 410 side, a lens 423 on the condenser lens unit 430 side, and a slit assembly 424. The holder 421 holds the pair of lenses 422, 423 and the slit assembly 424. The holder 421 maintains a constant positional relationship between the pair of lenses 422, 423 and the slit assembly 424 along the optical axis of the laser light L. The pair of lenses 422, 423 constitute a bilateral telecentric optical system, in which the reflection surface 410a of the reflective spatial light modulator 410 and the entrance pupil plane 430a of the condenser lens unit 430 are in an imaging relationship. Consequently, the image of the laser light L on the reflection surface 410a of the reflective spatial light modulator 410 (the image of the laser light L modulated by the reflective spatial light modulator 410) is transferred (imaged) onto the entrance pupil plane 430a of the condenser lens unit 430. A slit 424a is formed in the slit member 424. The slit 424a is located between the lens 422 and the lens 423, and is located near the focal plane of the lens 422. Unnecessary portions of the laser light L modulated and reflected by the reflective spatial light modulator 410 are blocked by the slit member 424. The laser light L, after passing through the 4f lens unit 420, is incident on the dichroic mirror 403 along the Y-axis direction.

[0074] The dichroic mirror 403 reflects most (e.g., 95-99.5%) of the laser light L along the Z-axis direction and transmits a portion (e.g., 0.5-5%) of the laser light L along the Y-axis direction. Most of the laser light L is reflected at right angles along the ZX plane by the dichroic mirror 403. After being reflected by the dichroic mirror 403, the laser light L is incident on the condenser lens unit 430 along the Z-axis direction.

[0075] The condenser lens unit 430 is attached to the end 401d (the end opposite to the end 401c) of the housing 401 in the Y-axis direction via a drive mechanism 440. The condenser lens unit 430 includes a holder 431 and a plurality of condenser lenses 432. The holder 431 holds the plurality of condenser lenses 432. The plurality of condenser lenses 432 focus on the object 1 (see FIG. 1 ) supported on the support table 230. Figure 1 ) converges the laser light L. The driving mechanism 440 moves the condensing lens unit 430 along the Z-axis direction by the driving force of the piezoelectric element.

[0076] The off-axis distance measuring sensor 450 is mounted on the end portion 401d of the housing 401 so as to be located on both sides of the condenser lens unit 430 in the X-axis direction. The off-axis distance measuring sensor 450 uses a first measuring laser (measuring laser) to obtain the image of the object 1 (see FIG. 1 ). Figure 1 ) of the incident surface of the laser beam. The off-axis distance measuring sensor 450 measures the object 1 (see Figure 1 ) emits a first measuring laser beam from an incident surface of the object 1 and receives the first measuring laser beam reflected by the incident surface, thereby acquiring first displacement information corresponding to the displacement of the incident surface of the object 1. Furthermore, the off-axis distance measurement sensor 450 can utilize a sensor using a triangulation method, a laser confocal method, a white light confocal method, a spectroscopic interferometry method, an astigmatism method, or the like.

[0077] The laser focusing unit 400 includes a beam splitter 461, a pair of lenses 462 and 463, and a camera 464 for monitoring the intensity distribution of the laser light L. The beam splitter 461 splits the laser light L after passing through the dichroic mirror 403 into a reflected component and a transmitted component. The laser light L reflected by the beam splitter 461 is incident on the pair of lenses 462 and 463 and the camera 464 in sequence along the Z-axis direction. The pair of lenses 462 and 463 constitute a bilateral telecentric optical system, in which the entrance pupil plane 430a of the focusing lens unit 430 and the imaging plane of the camera 464 are in an imaging relationship. As a result, the image of the laser light L at the entrance pupil plane 430a of the focusing lens unit 430 is transferred (imaged) onto the imaging plane of the camera 464. As described above, the image of the laser light L at the entrance pupil plane 430a of the focusing lens unit 430 is the image of the laser light L modulated by the reflective spatial light modulator 410. Therefore, in the laser processing apparatus 200 , the operating state of the reflective spatial light modulator 410 can be grasped by monitoring the imaging results of the camera 464 .

[0078] The laser focusing unit 400 also includes a beam splitter 471, a lens 472, and a camera 473 for monitoring the optical axis position of the laser light L. The beam splitter 471 splits the laser light L, which has passed through the beam splitter 461, into a reflected component and a transmitted component. The laser light L reflected by the beam splitter 471 is incident on the lens 472 and the camera 473 in sequence along the Z-axis direction. The lens 472 focuses the incident laser light L onto the imaging surface of the camera 473.

[0079] Multiple beam splitters 461 and 471 are disposed within a cylindrical body 404 extending from an end 401d of the housing 401 along the Y-axis direction. A pair of lenses 462 and 463 are disposed within a cylindrical body 405, which is disposed upright on the cylindrical body 404 along the Z-axis direction. A camera 464 is disposed at the end of the cylindrical body 405. A lens 472 is disposed within a cylindrical body 406, which is disposed upright on the cylindrical body 404 along the Z-axis direction. A camera 473 is disposed at the end of the cylindrical body 406. The cylindrical bodies 405 and 406 are disposed side by side in the Y-axis direction. Furthermore, the laser light L transmitted through the beam splitter 471 may be absorbed by a damper or the like disposed at the end of the cylindrical body 404, or may be used for an appropriate purpose.

[0080] like Figure 6 and Figure 7As shown, the laser focusing section 400 has a visible light source 481, a plurality of lenses 482, a graticule 483, a reflector 484, a semi-transparent mirror 485, a beam splitter 486, a lens 487, an observation camera (camera section) 488 and a coaxial ranging sensor 460. The visible light source 481 emits visible light V along the Z-axis direction. The plurality of lenses 482 parallelize the visible light V emitted from the visible light source 481. The graticule 483 assigns a mark to the visible light V. The reflector 484 reflects the visible light V parallelized by the plurality of lenses 482 in the X-axis direction. The semi-transparent mirror 485 splits the visible light V reflected by the reflector 484 into a reflection component and a transmission component. The visible light V reflected by the semi-transparent mirror 485 passes through the beam splitter 486 and the color separation mirror 403 in sequence along the Z-axis direction, and is irradiated onto the object 1 supported on the support table 230 via the focusing lens unit 430 (refer to Figure 1 ).

[0081] Visible light V irradiated on object 1 is reflected by the laser incident surface of object 1, enters dichroic mirror 403 via condensing lens unit 430, and then transmits dichroic mirror 403 along the Z-axis direction. Beam splitter 486 splits visible light V after passing through dichroic mirror 403 into a reflected component and a transmitted component. Furthermore, beam splitter 486 reflects the second measuring laser light L2 and its reflected light L2R, described later. Visible light V after passing through beam splitter 486 passes through semi-transparent mirror 485 and sequentially enters lens 487 and observation camera 488 along the Z-axis direction. Lens 487 focuses the incident visible light V onto the imaging surface of observation camera 488. Observation camera 488 images the laser incident surface of object 1. Observation camera 488 receives visible light V that enters the laser incident surface via graticule 483 and is reflected by the laser incident surface. In the laser processing apparatus 200 , the state of the object 1 can be grasped by observing the imaging results of the observation camera 488 .

[0082] Reflecting mirror 484, half-mirror 485, and beam splitter 486 are arranged within a holder 407 mounted on end 401d of housing 401. Multiple lenses 482 and reticle 483 are arranged within a cylindrical body 408, which is erected on holder 407 along the Z-axis direction. Visible light source 481 is arranged at the end of cylindrical body 408. Lens 487 is arranged within a cylindrical body 409, which is erected on holder 407 along the Z-axis direction. Observation camera 488 is arranged at the end of cylindrical body 409. Cylindrical bodies 408 and 409 are arranged side by side in the X-axis direction. Furthermore, visible light V that passes through half-mirror 485 in the X-axis direction and that is reflected in the X-axis direction by beam splitter 486 can be absorbed by a damper or the like provided on the wall of holder 407, or can be used for other purposes as appropriate.

[0083] The coaxial distance measuring sensor 460 (displacement information acquisition unit) is mounted on the side surface of the holder 407. The coaxial distance measuring sensor 460 measures the object 1 (see Figure 1 ) emits second measuring laser light L2 (measuring laser light) from the laser incident surface of the coaxial distance measuring sensor 460. Reflected light L2R of the second measuring laser light L2, after being reflected by the laser incident surface, is detected, thereby acquiring first displacement information corresponding to the displacement of the laser incident surface of the object 1. The second measuring laser light L2 emitted from the coaxial distance measuring sensor 460 is reflected by the beam splitter 486, passes through the dichroic mirror 403, and is guided to the condensing lens unit 430. There, it is reflected by the laser incident surface near the focal point of the condensing lens unit 430. This reflected light L2R returns to the coaxial distance measuring sensor 460 along a path opposite to that of the second measuring laser light L2. The coaxial distance measuring sensor 460 utilizes the fact that the state of the reflected light L2R changes depending on the position of the laser incident surface relative to the condensing lens unit 430 to acquire first displacement information of the object 1. For example, a sensor employing an astigmatic method or the like can be used as the coaxial distance measuring sensor 460.

[0084] like Figure 8 As shown, the off-axis distance measuring sensor 450 includes a light emitting element 451 such as a laser diode that emits a first measuring laser light L1, and a linear photodiode array (light receiving element array) 453 that receives the first measuring laser light L1 after being reflected on the laser incident surface of the object 1. The off-axis distance measuring sensor 450 is a triangulation distance measuring sensor that uses a triangulation distance measuring method. Here, the laser incident surface is the front surface 1a of the object 1 (see FIG. 1 ). Figure 2 ).

[0085] In heteroaxial ranging sensor 450, first measuring laser light L1 is emitted from light emitting element 451 in a direction oblique to the Z-axis. The emitted first measuring laser light L1 is focused toward object 1 by lens 452 and reflected by the laser incident surface. The reflected first measuring laser light L1 travels in a direction oblique to the Z-axis, is focused toward linear photodiode array 453 by lens 454, and is received at spot position SP of linear photodiode array 453.

[0086] The received position in the linear photodiode array 453, namely the spot position SP (hereinafter referred to as "spot position SP"), has a unique relationship with the displacement of the laser incident surface. Thus, the off-axis ranging sensor 450 obtains spot position information (light receiving position information) corresponding to the spot position (light receiving position) SP as first displacement information. Multiple linear photodiode arrays 453 may also be provided.

[0087] The control unit 500 performs a first alignment process, in which the second moving mechanism 240 is actuated based on the image capture results of the observation camera 488, thereby moving the laser focusing unit 400 in the Z-axis direction so that the Z-axis position of the focusing lens unit 430 (focusing lens 432) relative to the laser incident surface is aligned with the initial height position. When the focusing lens unit 430 is aligned with the initial height position through the first alignment process, the control unit 500 records information regarding the initial spot position SP0, i.e., the spot position SP obtained by the off-axis ranging sensor 450, in the storage unit of the control unit 500 as initial spot position information.

[0088] The initial height position is the position of the condenser lens unit 430 in the Z-axis direction when the mark of the reticle 483 is focused on the image of the laser incident surface captured by the observation camera 488 (hereinafter also referred to as the "reticle focus position") (see Figure 9 Here, the optical system is adjusted so that the markings on reticle 483 are in focus with the laser incident surface. That is, the reticle focus position is the position where the markings on reticle 483 are in focus with the laser incident surface. In other words, the reticle focus position is the position of condenser lens unit 430 in the Z-axis direction when the focus of condenser lens unit 430 is aligned with the laser incident surface.

[0089] Furthermore, if the optical system is adjusted so that the markings on reticle 483 are focused at a height position spaced a predetermined distance from the laser incident surface, rather than at the laser incident surface, the focused position of the markings on reticle 483 is not at the laser incident surface, but at the height position spaced a predetermined distance from the laser incident surface. If, as a result of the first alignment process performed by control unit 500, the focused state of the markings on reticle 483 cannot be recognized in the image of the laser incident surface captured by observation camera 488, "unprocessable determination processing" is executed to determine that object 1 is unprocessable.

[0090] The control unit 500 performs a light reception amount adjustment process, in which the inter-axial distance measurement sensor 450 is adjusted so that the light reception amount in the linear photodiode array 453 is equal to or greater than a threshold value. Examples of adjustments to the inter-axial distance measurement sensor 450 include increasing at least one of gain and exposure time, and increasing the output of the light emitting element 451.

[0091] Next, an example of laser processing performed in the above-mentioned laser processing apparatus 200 will be described. Figure 10 It will Figure 2 A schematic diagram showing a portion of the object shown in FIG. Figure 10 As shown in FIG. 1 , the object 1 is supported on the support table 230 in a state where the planned cutting line 5a is parallel to the X-axis direction (first processing state). Figure 20As shown in FIG. 2 , the cutting plan line 5b may be supported on the support table 230 in a state (second processing state) parallel to the X-axis direction. Figure 10 As shown, the front surface 1a of the object 1 that is the incident surface of the laser light L includes a device region DR corresponding to the functional element. The device region DR is two-dimensionally arranged along the X-axis direction and the Y-axis direction according to the arrangement of the functional elements.

[0092] In addition, the front surface 1a in the first processing state includes: a plurality of first cutting street regions SR1 extending along the X-axis direction (the first direction in the first processing state) and being regions between adjacent device regions DR along the Y-axis direction (the second direction in the first processing state); and a plurality of second cutting street regions SR2 extending along the Y-axis direction and being regions between adjacent device regions DR along the X-axis direction. In this example, the predetermined cutting line 5a of the scanning laser L is set at the center of the first cutting street region SR1, and the other predetermined cutting line 5b of the scanning laser L is set at the center of the second cutting street region SR2. Here, the case of scanning the laser L in the first cutting street region SR1 and using the off-axis distance measurement sensor 450 is first described.

[0093] In this case, in order to obtain first displacement information corresponding to the Z-axis displacement of the front surface 1a in the first cut street area SR1 (i.e., first displacement information indicating the Z-axis displacement of the first cut street area SR1), the first measuring laser light L1 of the off-axis ranging sensor 450 also scans the first cut street area SR1. Here, the width of the first cut street area SR1 in the Y-axis direction is narrower than the spot size of the first measuring laser light L1 on the front surface 1a. The spot size of the first measuring laser light L1 on the front surface 1a refers to, for example, the spot diameter of the first measuring laser light L1 on the front surface 1a when the laser focusing unit 400 is moved in the Z-axis direction by the second moving mechanism 240, and the focal point of the laser light L is aligned with the desired processing position in the Z-axis direction within the object 1.

[0094] Figure 11 : is a graph showing an example of first displacement information obtained by a different-axis distance measuring sensor. Figure 11 In each graph, the horizontal axis represents time (ie, position in the X-axis direction), and the vertical axis represents a voltage value indicating displacement. Figure 11 (a) shows the first displacement information DSa when the width of the first scribe line region SR1 is 15 μm and the spot diameter of the first measuring laser light L1 is 20 μm. Figure 11 (b) shows the first displacement information DSb when the width of the first scribe line region SR1 is 15 μm and the spot diameter of the first measuring laser light L1 is 15 μm. Figure 11(c) shows the first displacement information DSc when the width of the first scribe line region SR1 is 15 μm and the spot diameter of the first measuring laser light L1 is 10 μm.

[0095] Figure 11 The first displacement information DSc shown in (c) is a case where the spot diameter of the first measuring laser light L1 is smaller than the width of the first scribe line region SR1. Therefore, it can be considered that the noise caused by the first measuring laser light L1 irradiating the device region DR is relatively small, and the actual displacement of the first scribe line region SR1 can be more accurately represented. Figure 11 The first displacement information DSa shown in (a) is a case where the width of the first cutting path area SR1 is narrower than the spot diameter of the first measuring laser L1. Therefore, when the first measuring laser L1 is scanned on the first cutting path area SR1, a portion of the first measuring laser L1 is also irradiated to the device area DR. Therefore, it contains more noise caused by the influence of the device area DR (such as obstruction and reflection).

[0096] Therefore, in this case, the waveform of the first displacement information DSa becomes a waveform different from the actual displacement of the front surface 1a in the first scribe line region SR1, and the tracking accuracy of the focal point of the laser light L based on the first displacement information DSa may be reduced. Therefore, in the laser processing of this embodiment, such a reduction in the tracking accuracy of the focal point of the laser light L is suppressed. Figure 11 The first displacement information DSb shown in (b) has less noise than the first displacement information DSa, and its waveform is close to that of the first displacement information DSc.

[0097] Figure 12 Flowchart showing the laser processing method according to this embodiment. Figure 12 Each step of the laser processing method shown corresponds to each process performed by the control unit 500 (that is, each operation of the laser processing apparatus 200 ).

[0098] like Figure 12 As shown, here, first, the control unit 500 registers the pattern of the incident surface of the laser light L, i.e., the front surface 1a, of the object 1 (step S101). Next, the control unit 500 calculates the positions of the scanning laser light L and the first measuring laser light L1 based on the pattern registered in step S101 (step S102). Here, the position of the first scribe line region SR1 is calculated.

[0099] Next, the control unit 500 controls the off-axis distance measuring sensor 450 to obtain first displacement information corresponding to the displacement of the first scribe line region SR1 (step S103, first obtaining step). More specifically, Figure 13 and Figure 14As shown, in step S103, the control unit 500 first controls the first moving mechanism 220 to rotate the support table 230 to establish a first processing state. In this state, the first scribe line region SR1 (i.e., the planned cutting line 5a) calculated in step S102 is parallel to the X-axis direction. In this state, the control unit 500 positions the spot of the first measuring laser light L1 within the first scribe line region SR1.

[0100] Afterwards, the control unit 500 controls the off-axis distance measuring sensor 450 to irradiate the first measuring laser light L1, while controlling the first moving mechanism 220 to move the support table 230 along the X-axis direction. Thus, the control unit 500 scans the first cutting street area SR1 with the first measuring laser light L1. As a result, the off-axis distance measuring sensor 450 receives the reflected light on the front surface 1a of the first measuring laser light L1, and can obtain the first displacement information DS1 (refer to FIG. 1 ) indicating the displacement of the front surface 1a in the first cutting street area SR1. Figure 15 (a)).

[0101] Thus, the control unit 500 performs a first acquisition process in step S103, wherein the first measuring laser light L1 is scanned across the first scribe line region SR1, causing the off-axis ranging sensor 450 to acquire first displacement information DS1 within the first scribe line region SR1. Here, the first moving mechanism 220 is a moving mechanism that moves the irradiation area (beam spot) of the first measuring laser light L1 on the front surface 1a of the object 1 relative to the object 1.

[0102] The first scribe line region SR1 includes intersections CR with the second scribe line region SR2. Therefore, the first displacement information DS1 obtained here includes a plurality of intersection information corresponding to the intersections CR appearing at predetermined intervals (intervals between device regions DR in the X-axis direction) in the first scribe line region SR1. Figure 15 (a) shows the first displacement information DS1 obtained in step S103.

[0103] In the next step, the control unit 500 analyzes the first displacement information D1 obtained in step S103 (step S104, the second acquisition step). More specifically, in step S104, the control unit 500 first estimates the position of the intersection CR of the first cutting street area SR1 and the second cutting street area SR2 based on the concave-convex shape of the waveform of the first displacement information D1. The concave-convex shape of the waveform of the first displacement information DS1 has a tendency to protrude at the intersection CR and form a protrusion P. Therefore, here, as shown in FIG. Figure 15As shown in (b), the control unit 500 estimates the protrusion P of the concave-convex shape of the waveform of the first displacement information DS1 as the location of the intersection CR. The control unit 500 also extracts the displacement value (height in the Z-axis direction) at the estimated location of the intersection CR from the first displacement information DS1, i.e., the intersection information.

[0104] Then, if Figure 15 As shown in (c), the control unit 500 interpolates the intersection information extracted in step S104 in the X-axis direction (for example, linear interpolation), thereby acquiring the second displacement information DS2 from the first displacement information DS1 (step S105, second acquisition step).

[0105] Thus, in steps S104 and S105, the second displacement information DS2 is obtained based on the first displacement information DS1 obtained in step S103. That is, the control unit 500 performs a second acquisition process in steps S104 and S105, wherein a plurality of intersection point information corresponding to the intersection points CR of the first scribe line region SR1 and the second scribe line region SR2 is extracted from the first displacement information DS1 obtained in step S103, and the extracted plurality of intersection point information is interpolated in the X-axis direction (the first direction in the first processing state), thereby obtaining the second displacement information DS2 corresponding to the displacement of the first scribe line region SR1.

[0106] Figure 16 : is a graph showing an example of the first displacement information, the intersection information, and the second displacement information. Figure 16 (a) is a graph showing an example of the first displacement information DS1 obtained in step S103. Figure 16 (b) is a diagram showing an example of the intersection information DS1c extracted in step S104. Figure 16 (c) is a graph showing a comparison between the second displacement information DS2 acquired in step S105 and the first displacement information DSc when the spot diameter of the first measuring laser light L1 is smaller than the width of the first scribe line region SR1.

[0107] like Figure 16 As shown, the first displacement information DS1 contains a significant amount of noise caused by a portion of the first measuring laser light L1 irradiating the device region DR. In contrast, the second displacement information DS2, obtained by interpolating the intersection information DS1c, is sufficiently consistent with the first displacement information DSc, which is believed to more accurately represent the actual displacement of the first scribe line region SR1. In other words, it can be considered that the second displacement information DS2 more accurately reflects the actual displacement of the first scribe line region SR1 than the first displacement information DS1.

[0108] In addition, if Figure 17As shown, the pitch Pc (period) of the intersection points CR in the first displacement information DS1 varies according to the chip size of the object 1, that is, the size of the device region DR. Figure 15 In the example of FIG. 1 , the protrusion P indicating the intersection CR in the first displacement information DS1 is shown to be protruding toward the lower side (the side where the displacement becomes smaller), but Figure 18 As shown, there is a case where the protrusion P indicating the intersection CR in the first displacement information DS1 protrudes upward (toward a side where the displacement becomes larger).

[0109] In the following process, Figure 19 As shown, the control unit 500 performs tracking processing with the laser light L based on the second displacement information (process S106, processing process). More specifically, in process S106, the state is set such that the focal point of the laser light L is located in the first scribe line region SR1, where the second displacement information DS2 was obtained in processes S104 and S105. In this state, the control unit 500 controls the laser output unit 300 and the laser focusing unit 400 to irradiate the laser light L, while simultaneously controlling the first moving mechanism 220 to move the support stage 230 along the X-axis direction. This scans the laser light L across the first scribe line region SR1.

[0110] At this time, the control unit 500 controls the drive mechanism 440 to move the focusing lens unit 430 along the Z-axis direction based on the second displacement information DS2 (i.e., according to the displacement of the first scribe line region SR1 in the Z-axis direction), thereby maintaining a constant distance between the focal point of the laser light L and the front surface 1a of the object 1. Thus, laser processing of the object 1 is performed by irradiating the object 1 with the laser light L along the planned cutting line 5a set in the first scribe line region SR1 and tracking the displacement of the front surface 1a. As a result, a modified region is formed in the object 1 along the planned cutting line 5a in the first scribe line region SR1, completing the series of steps.

[0111] Thus, in step S106, the laser beam L is scanned across the object 1, thereby forming a modified region in the object 1. Specifically, in step S106, the control unit 500 performs a first processing operation in which the laser beam L is scanned across the first scribe line region SR1 while adjusting the position of the focal point of the laser beam L in the Z-axis direction intersecting the front surface 1a, the incident surface of the laser beam L, on the object 1 based on the second displacement information, thereby forming a modified region in the object 1. Here, the first moving mechanism 220 and the drive mechanism 440 are moving mechanisms that cause the focal point of the laser beam L to move relative to the object 1.

[0112] Furthermore, in this embodiment, the scanning of the first measuring laser light L1 in step S103 and the scanning of the laser light L in step S106 are partially repeated. Specifically, since the off-axis distance measuring sensor 450 is used in step S103, the off-axis distance measuring sensor 450 is arranged so as to precede the laser focusing unit 400 in the scanning direction (X-axis direction) of the first measuring laser light L1 and the laser light L, and the scanning of the first measuring laser light L1 is started in this state.

[0113] Thus, first displacement information DS1 is sequentially acquired, and the control unit 500 analyzes the sequentially acquired first displacement information DS1 to sequentially generate second displacement information DS2. The control unit 500 then adjusts the position of the focal point of the subsequent laser light L based on the sequentially generated second displacement information DS2 while scanning the laser light L. In this manner, tracking processing can be performed while acquiring information indicating the displacement of the first scribe line region SR1.

[0114] By performing the above-described steps S103 to S106 on all the first scribe line regions SR1 , the formation of the modified regions along all the lines to cut 5 a is completed.

[0115] As described above, in the laser processing apparatus 200 and laser processing method of this embodiment, the off-axis ranging sensor 450 irradiates the first measuring laser light L1 onto the front surface 1a of the object 1, which is the incident surface of the laser light, and receives the reflected light of the first measuring laser light L1 from the front surface 1a, thereby obtaining first displacement information DS1 corresponding to the displacement of the front surface 1a. Thus, the laser light L can be scanned while the focal point of the laser light L tracks the displacement of the front surface 1a based on this first displacement information DS1.

[0116] In particular, the object 1 includes, on its front surface 1a, a plurality of device regions DR arranged along intersecting X- and Y-axis directions; a plurality of first scribe street regions SR1 extending along the X-axis between the device regions DR; and a plurality of second scribe street regions SR2 extending along the Y-axis between the device regions DR. Furthermore, when acquiring first displacement information DS1, the first measuring laser light L1 is scanned across the first scribe street regions SR1. Consequently, the first measuring laser light L1 may also irradiate the device regions DR, potentially increasing noise in the first displacement information DS1.

[0117] In this regard, in the laser processing apparatus 200 and laser processing method of this embodiment, multiple intersection point information DS1c corresponding to the intersection points CR between the first scribe line region SR1 and the second scribe line region SR2 are extracted from the first displacement information DS1. This extracted multiple intersection point information DS1c is interpolated to obtain second displacement information DS2 corresponding to the displacement of the first scribe line region SR1. Then, based on this second displacement information DS2, the laser beam L is scanned across the first scribe line region SR1 while adjusting the position of the focal point of the laser beam L in the Z-axis direction intersecting the front surface 1a. This forms a modified region on the object 1.

[0118] At the intersection CR between the first scribe street region SR1 and the second scribe street region SR2, there is no device region DR in the width direction of the first scribe street region SR1, i.e., in the Y-axis direction (i.e., the second scribe street region SR2 extends in the Y-axis direction). Therefore, the first measuring laser light L1 is less likely to irradiate the device region DR than in areas other than the intersection CR of the first scribe street region SR1. Consequently, in the intersection information DS1c corresponding to the intersection CR in the first displacement information DS1, the noise caused by the first measuring laser light L1 irradiating the device region DR is relatively small.

[0119] Therefore, the second displacement information DS2, obtained by interpolating the plurality of intersection point information DS1c in the first displacement information DS1 in the X-axis direction, is less affected by noise and more accurately reflects the actual displacement of the first scribe line region SR1. Consequently, when forming a modified region on the object 1, utilizing this second displacement information DS2 can suppress a decrease in the tracking accuracy of the focal point of the laser light L in the Z-axis direction.

[0120] In particular, in this embodiment, the width of the first scribe street region SR1 in the Y-axis direction is narrower than the spot diameter of the first measurement laser light L1 on the front surface 1a. Therefore, as described above, a portion of the first measurement laser light L1 is more likely to irradiate the device region DR. Consequently, the influence of noise in the first displacement information DS1 is greater in areas other than the intersection CR of the first scribe street region SR1 with the second scribe street region SR2. Therefore, using the second displacement information DS2, obtained by interpolating the relatively less noisy intersection information DS1c within the first displacement information DS1, is more advantageous.

[0121] Furthermore, in the laser processing apparatus 200 of this embodiment, in step S104 (second acquisition processing), the control unit 500 estimates the position of the intersection point CR between the first street region SR1 and the second street region SR2 based on the concavo-convex shape of the waveform of the first displacement information DS1, and extracts the intersection point information DS1c from the first displacement information DS1 based on the estimated position. Therefore, for example, it is not necessary to calculate the position of the intersection point CR between the first street region SR1 and the second street region SR2 based on the pattern of the front surface 1a of the object 1.

[0122] Furthermore, in the laser processing apparatus 200 of this embodiment, the control unit 500 can estimate, in step S104 (second acquisition processing), the protruding portion P of the concavo-convex shape of the waveform of the first displacement information DS1 as the position of the intersection CR between the first scribe line region SR1 and the second scribe line region SR2. Therefore, based on the concavo-convex shape of the waveform of the first displacement information DS1, the intersection point information DS1c can be more reliably extracted from the first displacement information DS1.

[0123] Here, after the laser processing in all the first scribe line regions SR1 (ie, all the planned cutting lines 5a) is completed, Figure 20 and Figure 21 In this case, the control unit 500 first controls the first moving mechanism 220 to rotate the support table 230 to set the second processing state. In this state, the second scribe line SR2 (i.e., the planned cutting line 5b) calculated in step S102 is parallel to the X-axis direction.

[0124] The control unit 500 then performs steps S103 to S106 on the second street region SR2. Consequently, a modified region is formed along the planned cutting line 5b in the second street region SR2 on the object 1. Furthermore, the width of the second street region SR in the direction in which the second street region SR2 extends is also narrower than the spot diameter of the first measuring laser light L1 on the front surface 1a.

[0125] In this way, the control unit 500 can perform the third acquisition process (step S103 ) in which the first measuring laser light L1 is scanned on the second street region SR2 to cause the heteroaxial distance measuring sensor 450 to acquire the first displacement information DS1 in the second street region SR2 .

[0126] In addition, the control unit 500 can implement a fourth acquisition process (steps S104 and S105), wherein a plurality of intersection information DS1c corresponding to the intersection CR of the second cutting road area SR2 and the first cutting road area SR1 is extracted from the first displacement information DS1 obtained by the third acquisition process, and the plurality of intersection information DS1c extracted are interpolated in the X-axis direction (the second direction in the second processing state), thereby obtaining third displacement information DS3 corresponding to the displacement of the second cutting road area SR2 (refer to Figure 21 (c)).

[0127] Furthermore, the control unit 500 is capable of performing a second processing (process S106), wherein the position of the focal point of the laser L in the Z-axis direction intersecting the incident surface of the laser L of the object 1, i.e., the front surface 1a, is adjusted based on the third displacement information DS3, while scanning the laser L on the second cutting path area SR2, thereby forming a modified area in the object 1.

[0128] In this case, when the second cut street region SR2 is scanned with laser light L, similarly to the case of the first cut street region SR1, the first measuring laser light L1 is scanned across the second cut street region SR2 to obtain first displacement information DS1 corresponding to the displacement of the second cut street region SR2. Then, intersection point information DS1c is extracted from this first displacement information DS1, and the extracted intersection point information DS1c is interpolated in the X-axis direction to obtain third displacement information DS3 that more accurately reflects the actual displacement of the second cut street region SR2. Consequently, when the second cut street region SR2 is scanned with laser light L, it is possible to more reliably suppress a decrease in the tracking accuracy of the focal point of laser light L in the Z-axis direction, which intersects the front surface 1a of the object 1, the incident surface of laser light L.

[0129] The above embodiment illustrates one aspect of the laser processing apparatus and laser processing method disclosed herein. The laser processing apparatus and laser processing method disclosed herein are not limited to the above embodiment and can be modified arbitrarily. Next, a modification example will be described.

[0130] In the above embodiment, the case where the width of the first scribe line region SR1 (and the second scribe line region SR2) is narrower than the spot size of the first measuring laser light L1 on the front surface 1a of the object 1 is exemplified. Figure 22 As shown, the size of the spot of the first measuring laser light L1 on the front surface 1 a of the object 1 may be smaller than the width of the first scribe line region SR1 (and the second scribe line region SR2 ).

[0131] exist Figure 22In the example shown in FIG1 , two parallel lines to cut 5a are defined for a first scribe line region SR1 (i.e., double-line processing is performed). Furthermore, each line to cut 5a is offset to one side or the other in the Y-axis direction relative to the center of the first scribe line region SR1. In step S106, the laser beam L is scanned along these lines to cut 5a across the first scribe line region SR1.

[0132] Therefore, the position at which the off-axis ranging sensor 450 acquires the first displacement information DS1 also becomes a position closer to one side or the other in the Y-axis direction than the center of the first scribe line region SR1. In other words, in step S103, the spot of the first measuring laser light L1 is aligned closer to one side or the other in the Y-axis direction than the center of the first scribe line region SR1. Therefore, as described above, even if the spot size of the first measuring laser light L1 on the front surface 1a of the object 1 is smaller than the width of the first scribe line region SR1, a portion of the first measuring laser light L1 may still irradiate the device region DR.

[0133] Therefore, in this case, similar to the above-mentioned embodiment, multiple intersection point information DS1c corresponding to the intersection point Cr between the first cutting road area SR1 and the second cutting road area SR2 are extracted from the first displacement information DS1 obtained in process S103, and the extracted multiple intersection point information DS1c are interpolated in the X-axis direction to obtain the second displacement information DS2, and tracking processing using the second displacement information DS2 can be performed.

[0134] As described above, in the laser processing apparatus 200, during the first acquisition process (step S103) and the first processing process (step S106), the control unit 500 can scan the first measuring laser light L1 and the laser light L at a position closer to one side (or the other side) in the Y-axis direction than the center of the first scribe line region SR1 in the Y-axis direction. In this case, the influence of noise in the first displacement information DS1 may be greater in the region other than the intersection CR with the second scribe line region SR2 in the first scribe line region SR1. Therefore, it is more advantageous to use the second displacement information DS2 obtained by interpolating the intersection point information DS1c, which has relatively less noise in the first displacement information DS1.

[0135] On the other hand, Figure 23 As shown, multiple structures T (e.g., metal pads or resin films) with different reflectivities may be formed in the first scribe line region SR1 (or the second scribe line region SR2). In this case, the amount of light reflected by the first measuring laser light L1 varies depending on the reflectivity of each structure T, making it difficult to obtain first displacement information DS1 that accurately reflects the displacement of the first scribe line region SR1.

[0136] Therefore, in this case, the control unit 500 may extract displacement information at a position corresponding to a specific structure T having the same reflectivity from the first displacement information DS1 obtained by scanning the first measuring laser light L1 across the first scribe line region SR1, and interpolate the extracted displacement information in the X-axis direction to obtain second displacement information DS2 that more accurately reflects the actual displacement of the first scribe line region SR1. In this case, the structure T for which the displacement information is to be extracted may be the structure T located at the intersection of the first scribe line region SR1 and the second scribe line region SR2.

[0137] In this case, the width of the first scribe line region SR1 (or the second scribe line region SR2) may be narrower or wider than the spot size of the first measuring laser light L1. However, when the width of the first scribe line region SR1 (or the second scribe line region SR2) is narrower than the spot size of the first measuring laser light L1, as described above, it is effective to extract displacement information (i.e., intersection information DS1c) for the structure T formed at the intersection CR between the first scribe line region SR1 and the second scribe line region SR2.

[0138] Furthermore, in the above embodiment, an off-axis distance measuring sensor 450 is used as the displacement information acquisition unit for acquiring the first displacement information DS1. However, in the laser processing apparatus 200, a coaxial distance measuring sensor 460 can also be used as the displacement information acquisition unit for acquiring the first displacement information DS1. In this case, the optical axis of the second measuring laser light L2 from the coaxial distance measuring sensor 460 is coaxial with the optical axis of the processing laser light L. This makes it difficult to partially overlap steps S103 and S106 as in the above embodiment. In other words, it is difficult to sequentially acquire the first displacement information DS1 (i.e., the second displacement information DS2) by first using the second measuring laser light L2 while performing processing using the subsequent laser light L.

[0139] Therefore, in this case, the control unit 500 first performs steps S103 to S105 on at least one first scribe area SR1, thereby acquiring first displacement information DS1 and second displacement information DS2 corresponding to the displacement of the first scribe area SR1. The control unit 500 then performs step S106 on the first scribe area SR1 for which the second displacement information DS2 has been acquired, thereby performing tracking processing. This achieves the same effect as when using the off-axis distance measurement sensor 450.

[0140] In addition, when using the coaxial ranging sensor 460, the size of the spot of the second measuring laser L2 on the front surface 1a refers to, for example, the spot diameter of the second measuring laser L2 on the front surface 1a at the position in the Z-axis direction of the focusing lens unit 430 (i.e., the focusing position of the graticule) when the mark of the graticule 483 is focused on the image of the laser incident surface taken by the observation camera 488.

[0141] Furthermore, in the above embodiment, the control unit 500 estimates the position of the intersection point CR based on the concavo-convex shape of the waveform of the first displacement information DS1 in steps S104 and S105, and extracts the intersection point information DS1c from the first displacement information DS1 based on the estimated position. However, in the laser processing apparatus 200, the control unit 500 may also calculate the position of the intersection point CR based on the pattern of the front surface 1a of the object 1 registered in step S101.

[0142] That is, in the second acquisition process (steps S104 and S105), the control unit 500 may calculate the position of the intersection point CR between the first cut street region SR1 and the second cut street region SR2 based on the pattern information including the patterns of the first cut street region SR1 and the second cut street region SR2 on the front surface 1a, and extract the intersection point information DS1c from the first displacement information DS1 based on the calculated position. In this case, when extracting the intersection point information DS1c from the first displacement information DS1, it is not necessary to estimate the position of the intersection point CR between the first cut street region SR1 and the second cut street region SR2. Thus, the intersection point information DS1c can be extracted more reliably and in a shorter time.

[0143] [Explanation of Reference Numerals]

[0144] 1…object, 1a…front surface (incident surface), 200…laser processing device, 220…first moving mechanism (moving mechanism), 230…support table (support portion), 400…laser focusing portion (irradiation portion), 440…driving mechanism (moving mechanism), 450…heteroaxial distance measuring sensor (displacement information acquisition portion), 460…coaxial distance measuring sensor (displacement information acquisition portion), 500…control portion, L…laser, L1…first measuring laser (measuring laser), L2…second measuring laser (measuring laser), SR1…first cutting path region, SR2…second cutting path region, CR…intersection, DS1…first displacement information, DS1c…intersection information, DS2…second displacement information, P…protrusion.

Claims

1. A laser processing device, wherein: It is a laser processing device for irradiating an object with laser light to form a modified area. have: a supporting portion for supporting the object; an irradiation unit configured to irradiate the object supported by the support unit with the laser beam; a displacement information acquiring unit configured to irradiate a surface of the object supported by the supporting unit with a measuring laser beam and receive reflected light of the measuring laser beam from the incident surface to thereby acquire first displacement information corresponding to a displacement of the incident surface; a moving mechanism for moving the focal point of the laser light and the irradiation area of ​​the measuring laser light relative to the object; and a control unit configured to control the moving mechanism so that the laser light and the measuring laser light scan the object, in, When viewed from a direction intersecting the incident surface, the incident surface of the object includes: a plurality of device regions arranged along a first direction and a second direction intersecting each other; a plurality of first scribe line regions extending along the first direction and being regions between the device regions adjacent to each other along the second direction; and a plurality of second scribe line regions extending along the second direction and being regions between the device regions adjacent to each other along the first direction; The control unit performs the following processing: a first acquisition process, wherein the displacement information acquisition unit acquires the first displacement information in the first scribe line area by scanning the measuring laser beam across the first scribe line area; a second acquisition process, wherein a plurality of intersection point information corresponding to intersection points of the first cutting street area and the second cutting street area is extracted from the first displacement information obtained by the first acquisition process, and the plurality of intersection point information extracted is interpolated in the first direction to thereby obtain second displacement information corresponding to the displacement of the first cutting street area; and The first processing comprises scanning the laser beam over the first street region while adjusting the position of the focal point in a direction intersecting the incident surface based on the second displacement information, thereby forming the modified region on the object.

2. The laser processing device according to claim 1, wherein: The width of the first scribe line region in the second direction is narrower than the size of the spot of the measuring laser light on the incident surface.

3. The laser processing device according to claim 1 or 2, wherein: In the first acquisition process and the first processing process, the control unit scans the measuring laser light and the laser light at a position closer to one side in the second direction than the center of the first scribe line area in the second direction.

4. The laser processing device according to any one of claims 1 to 3, wherein In the second acquisition process, the control unit estimates the position of the intersection between the first street area and the second street area based on the concavo-convex shape of the waveform of the first displacement information, and extracts the intersection information from the first displacement information based on the estimated position.

5. The laser processing device according to claim 4, wherein: In the second acquisition process, the control unit estimates a protruding portion of the concavo-convex shape of the waveform of the first displacement information as a position of an intersection of the first street region and the second street region.

6. The laser processing device according to any one of claims 1 to 3, wherein In the second acquisition process, the control unit calculates the position of the intersection of the first cutting path area and the second cutting path area based on the pattern information of the pattern including the first cutting path area and the second cutting path area on the incident surface, and extracts the intersection information from the first displacement information based on the calculated position.

7. The laser processing device according to any one of claims 1 to 6, wherein The control unit performs the following processing: a third acquisition process, wherein the displacement information acquisition unit acquires the first displacement information in the second street area by scanning the measuring laser beam across the second street area; a fourth acquisition process, wherein a plurality of intersection point information corresponding to intersection points of the second cutting street area and the first cutting street area is extracted from the first displacement information obtained by the third acquisition process, and the extracted plurality of intersection point information is interpolated in the second direction to thereby obtain third displacement information corresponding to the displacement of the second cutting street area; and The second processing comprises scanning the laser beam over the second street region while adjusting the position of the focal point in a direction intersecting the incident surface based on the third displacement information, thereby forming the modified region on the object.

8. A laser processing method, wherein: It is a laser processing method for irradiating an object with laser light to form a modified area. have: a first acquisition step of irradiating a surface of the object for incident light with a measuring laser beam and receiving reflected light of the measuring laser beam from the incident surface to thereby acquire first displacement information corresponding to a displacement of the incident surface; a second obtaining step of obtaining second displacement information based on the first displacement information; and a processing step, wherein the modified region is formed on the object by scanning the laser beam on the object, in, When viewed from a direction intersecting the incident surface, the incident surface of the object includes: a plurality of device regions arranged along a first direction and a second direction intersecting each other; a plurality of first scribe line regions extending along the first direction and being regions between the device regions adjacent to each other along the second direction; and a plurality of second scribe line regions extending along the second direction and being regions between the device regions adjacent to each other along the first direction; and, In the first acquisition step, the first displacement information in the first scribe line area is acquired by scanning the measuring laser beam on the first scribe line area. In the second acquisition process, a plurality of intersection point information corresponding to the intersection points of the first cutting road area and the second cutting road area are extracted from the first displacement information obtained by the first acquisition process, and the extracted plurality of intersection point information are interpolated in the first direction, thereby obtaining second displacement information corresponding to the displacement of the first cutting road area. In the processing step, the laser beam is scanned over the first street region while adjusting the position of the focal point in a direction intersecting the incident surface based on the second displacement information, thereby forming the modified region on the object.

Images