Laser processing apparatus and laser processing method

Abstract

To provide a laser processing apparatus and a laser processing method capable of suppressing a decrease in tracking accuracy of laser light.SOLUTION: A control part 500 performs: a first acquisition process of acquiring first displacement information DS1 in a first street region SR1 by scanning the first street region SR1 with first measurement laser light L1; a second acquisition process of extracting a plurality of pieces of intersection information DS1c corresponding to an intersection CR from the first displacement information DS1 and interpolating the extracted plurality of pieces of intersection information DS1c in an X-axis direction to acquire second displacement information DS2 according to the displacement of a first street region SR1; and a first processing process of scanning the first street region SR1 with laser light L while adjusting a position of a condensing point in a Z-axis direction based on the second displacement information DS2.SELECTED DRAWING: Figure 16

Description

[Technical Field]

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

[0002] Patent Document 1 describes a laser processing device. This laser processing device includes a stage 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 of the AF laser light to obtain a displacement signal related to the displacement of the reflecting surface. The AF unit also inputs a voltage signal to the drive unit so 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 follow the displacement of the reflecting surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-113068 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above technical field, there are cases where the laser light incident surface of an object includes two-dimensionally arranged device regions and street regions that pass between adjacent device regions, and the laser light is scanned over the street regions to form modified regions in the object. In this case, the AF laser light is also scanned over the street regions to obtain the displacement of the street regions. This makes it possible to scan the laser light while causing the focal point of the laser light to follow the displacement of the street regions.

[0005] In this case, for example, if the spot diameter of the AF laser light on the incident surface is larger than the width of the street area, part of the AF laser light will also be irradiated onto the device area. Alternatively, even if the spot diameter of the AF laser light on the incident surface is smaller than the width of the street area, for example, when scanning with the AF laser light on the device area side of the center of the street area, part of the AF laser light will also be irradiated onto the device area. In such cases, when the AF laser light is also irradiated onto the device area, the displacement signal acquired based on the reflected light of the AF laser light will contain a lot of noise due to the influence of the device area (e.g., occlusion or reflection). Therefore, the waveform of the displacement signal will differ from the actual displacement of the incident surface in the street area, which may reduce the accuracy of tracking the focal point of the laser light based on the displacement signal.

[0006] Therefore, an object of the present invention is to provide a laser processing apparatus and a laser processing method that can suppress a decrease in the tracking accuracy of laser light. [Means for solving the problem]

[0007] a displacement information acquiring unit that acquires first displacement information according to a displacement of the incident surface by irradiating a laser beam onto the object supported by the support unit with a measurement laser beam and receiving reflected light of the measurement laser beam from the incident surface; a movement mechanism that moves a focusing point of the laser beam on the object and an irradiation area of ​​the measurement laser beam relative to the object; and a control unit that controls the movement mechanism to scan the laser beam and the measurement laser beam over the object, wherein when viewed from a direction intersecting the incident surface, the incident surface of the object is defined by a plurality of device regions arranged along a first direction and a second direction intersecting each other, and a region between the device regions adjacent to each other along the second direction, a plurality of first street regions extending along the first direction; and a plurality of second street regions extending along the second direction, which are regions between the device regions adjacent to each other along the first direction, wherein the control unit performs a first acquisition process to cause the displacement information acquisition unit to acquire the first displacement information in the first street regions by scanning the measurement laser light over the first street regions; a second acquisition process to extract, from the first displacement information acquired in the first acquisition process, a plurality of intersection information corresponding to intersections between the first street regions and the second street regions and interpolate the extracted plurality of intersection information in the first direction to acquire second displacement information corresponding to the displacement of the first street regions; and a first processing process to form the modified region in the object by scanning the laser light over the first street regions while adjusting the position of the focal point in a direction intersecting the incident plane based on the second displacement information.

[0008] The laser processing method according to the present invention is [8] "a laser processing method for irradiating a laser beam onto an object to form a modified region, the method comprising: a first acquisition step of irradiating a laser beam incident surface of the object with a measurement laser beam and receiving reflected light of the measurement laser beam from the incident surface to acquire first displacement information corresponding to a displacement of the incident surface; a second acquisition step of acquiring second displacement information based on the first displacement information; and a processing step of scanning the object with the laser beam to form the modified region in the object, wherein, when viewed from a direction intersecting the incident surface, the incident surface of the object is formed into a plurality of device regions arranged along a first direction and a second direction intersecting each other, a region between the device regions adjacent along the second direction, the region including a plurality of first street regions extending along the first direction, and a region between the device regions adjacent along the first direction. and a plurality of second street areas extending along the second direction, the first acquisition step comprising scanning the measurement laser light over the first street areas to acquire the first displacement information in the first street areas; the second acquisition step comprising extracting, from the first displacement information acquired in the first acquisition step, pieces of intersection information corresponding to intersections between the first street area and the second street area, and interpolating the extracted pieces of intersection information in the first direction to acquire second displacement information corresponding to displacements of the first street areas; and the processing step comprising scanning the laser light over the first street areas while adjusting the position of a focal point of the laser light in a direction intersecting the incident plane based on the second displacement information, thereby forming the modified area in the object.

[0009] In this laser processing apparatus and method, a measurement laser beam is irradiated onto a laser beam incident surface of an object, and the reflected light of the measurement laser beam is received at the incident surface, thereby acquiring first displacement information corresponding to the displacement of the incident surface. Therefore, based on this first displacement information, it is possible to scan the laser beam while causing the focal point of the laser beam to follow the displacement of the incident surface. In particular, the object here includes, on the laser beam incident surface, a plurality of device regions arranged along a first direction and a second direction that intersect with each other, a plurality of first street regions between the device regions that extend along the first direction, and a plurality of second street regions between the device regions that extend along the second direction. When acquiring the first displacement information, the measurement laser beam is scanned over the first street regions. Therefore, there is a risk of increased noise in the first displacement information due to the measurement laser beam also being irradiated onto the device regions.

[0010] In contrast, in this laser processing device and laser processing method, multiple pieces of intersection information corresponding to the intersections between the first street area and the second street area are extracted from the first displacement information, and the extracted multiple pieces of intersection information are interpolated to obtain second displacement information corresponding to the displacement of the first street area. Then, based on the second displacement information, the laser beam is scanned over the first street area while adjusting the position of the focal point in a direction intersecting the incident plane, thereby forming a modified area in the target object.

[0011] At the intersections of the first and second street regions, there is no device region in the second direction, which is the width direction of the first street region (i.e., the second street region extends in the second direction). Therefore, the measurement laser light is less likely to irradiate the device region compared to regions other than the intersections of the first street region. Therefore, the intersection information corresponding to the intersection in the first displacement information has relatively little noise caused by the measurement laser light being irradiated onto the device region. Therefore, the second displacement information obtained by interpolating multiple intersection information in the first displacement information in the first direction is less affected by noise and more accurately reflects the actual displacement of the first street region. Therefore, when forming a modified region in an object, by using this second displacement information, it is possible to suppress a decrease in the tracking accuracy of the focal point of the laser light in the direction intersecting the incident surface.

[0012] The laser processing apparatus according to the present invention may be [2] "the laser processing apparatus according to the above [1], in which the width of the first street region in the second direction is narrower than the size of the spot of the measurement laser light on the incident surface." In this case, as described above, a portion of the measurement laser light is more likely to be irradiated onto the device region. Therefore, the influence of noise in the first displacement information becomes greater in regions of the first street region other than the intersections with the second street region. Therefore, it is more advantageous to use second displacement information obtained by interpolating intersection information with relatively less noise from the first displacement information.

[0013] The laser processing device according to the present invention may be [3] "the laser processing device according to the above [1] or [2], wherein the control unit, in the first acquisition process and the first processing process, scans the measurement laser light and the laser light on one side of the center of the first street area in the second direction." In this case, too, as described above, a portion of the measurement laser light is likely to be irradiated onto the device area. Therefore, the influence of noise in the first displacement information becomes greater in areas of the first street area other than the intersections with the second street area. Therefore, it is more advantageous to use second displacement information obtained by interpolating intersection information with relatively less noise from the first displacement information.

[0014] The laser processing device according to the present invention may be [4] "the laser processing device according to any one of the above [1] to [3], wherein the control unit, in the second acquisition process, 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." In this case, it is not necessary to determine the position of the intersection between the first street area and the second street area based on, for example, the pattern of the incident surface of the object.

[0015] The laser processing device according to the present invention may be [5] "the laser processing device according to the above [4], wherein the control unit, in the second acquisition process, estimates a protruding portion of the uneven shape of the waveform of the first displacement information as the position of an intersection between the first street area and the second street area." In this case, the intersection information can be extracted more reliably from the first displacement information based on the uneven shape of the waveform of the first displacement information.

[0016] The laser processing apparatus according to the present invention may be [6] "the laser processing apparatus according to any one of [1] to [3] above, wherein, in the second acquisition process, the control unit determines the position of the intersection between the first street area and the second street area based on pattern information including patterns of the first street area and the second street area on the incident surface, and extracts the intersection information from the first displacement information based on the determined 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 between the first street area and the second street area. Therefore, it is possible to extract the intersection information more reliably and in a shorter time.

[0017] Here, after scanning of all first street areas with the measurement laser light and the laser light is completed, multiple pieces of first displacement information corresponding to the respective displacements of all first street areas are obtained. Each of the multiple pieces of first displacement information includes intersection information corresponding to the intersection between the first street area and the second street area. Therefore, when scanning the second street area with the laser light, it is possible to use new displacement information obtained by interpolating the intersection information in the second direction. In this case, there is an advantage in that scanning the second street area with the measurement laser light is not required when scanning the second street area with the laser light.

[0018] On the other hand, when the scanning of the first street region with the laser light is completed and a modified region is formed in the object, there is a risk that deformation such as warping may occur in the object. In this case, the interpolation of intersection information included in the first displacement information already acquired by operating the measurement laser on the first street region may not reflect the actual displacement of the second street region, including the deformation of the object caused by the formation of the modified region. Therefore, the laser processing device according to the present invention may have the following configuration.

[0019] That is, the laser processing apparatus of the present invention may be [7] "a laser processing apparatus described in any of [1] to [6] above, wherein the control unit performs a third acquisition process in which the control unit causes the displacement information acquisition unit to acquire the first displacement information in the second street area by scanning the measurement laser light over the second street area; a fourth acquisition process in which the control unit extracts, from the first displacement information acquired in the third acquisition process, a plurality of intersection information corresponding to intersections between the second street area and the first street area and interpolates the extracted plurality of intersection information in the second direction to acquire third displacement information corresponding to the displacement of the second street area; and a second processing process in which the control unit forms the modified area on the object by scanning the laser light over the second street area while adjusting the position of the focal point in a direction intersecting the incident plane based on the third displacement information."

[0020] In this case, when scanning the second street area with the laser light, the second street area is scanned with the measurement laser light in the same manner as the first street area, thereby obtaining first displacement information corresponding to the displacement of the second street area. Then, intersection information is extracted from the first displacement information, and the extracted intersection information is interpolated in the second direction to obtain third displacement information that more accurately reflects the actual displacement of the second street area. Therefore, even when scanning the second street area with the laser light, it is possible to more reliably prevent a decrease in the tracking accuracy of the focal point of the laser light in the direction intersecting the incident plane. [Effects of the Invention]

[0021] According to the present invention, it is possible to provide a laser processing apparatus and a laser processing method that can suppress a decrease in the tracking accuracy of laser light. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a perspective view showing a laser processing device according to an embodiment. [Figure 2]FIG. 2 is a perspective view of an object attached to a support base of the laser processing apparatus according to the embodiment. [Figure 3] FIG. 3 is a cross-sectional view taken along the XY plane of FIG. [Figure 4] FIG. 4 is a perspective view showing a part of a laser output unit and a laser focusing unit of the laser processing device according to the embodiment. [Figure 5] FIG. 5 is a cross-sectional view taken along the XY plane of FIG. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. [Figure 8] FIG. 8 is a front view showing a schematic configuration of the different-axis distance measuring sensor according to the embodiment. [Figure 9] FIG. 9 is a diagram showing a state in which the reticle marks are in focus in an image of the laser light incident surface captured by an observation camera according to the embodiment. [Figure 10] FIG. 10 is a schematic diagram showing an enlarged portion of the object shown in FIG. [Figure 11] FIG. 11 is a graph showing an example of the first displacement information acquired by the other-axis distance measuring sensor. [Figure 12] FIG. 12 is a flowchart showing the laser processing method according to this embodiment. [Figure 13] FIG. 13 is a diagram showing one step of the laser processing method shown in FIG. [Figure 14] FIG. 14 is a diagram showing one step of the laser processing method shown in FIG. [Figure 15] FIG. 15 is a diagram showing one step of the laser processing method shown in FIG. [Figure 16] FIG. 16 is a graph showing an example of the first displacement information, the intersection information, and the second displacement information. [Figure 17] FIG. 17 is a graph showing another example of the first displacement information. [Figure 18] FIG. 18 is a graph showing yet another example of the first displacement information. [Figure 19] FIG. 19 is a diagram showing one step of the laser processing method shown in FIG. [Figure 20] FIG. 20 is a diagram showing one step of laser processing of the second street region. [Figure 21] FIG. 21 is a graph showing an example of the first displacement information and the third displacement information. [Figure 22] FIG. 22 is a diagram showing the state of laser processing according to the modified example. [Figure 23] FIG. 23 is a diagram showing an object according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0023] A laser processing apparatus and a laser processing method according to one embodiment will be described below with reference to the drawings. In each drawing, the same or corresponding elements are denoted by the same reference numerals, and redundant explanations may be omitted. Each drawing may also show 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. As an example, the X-axis and Y-axis directions are horizontal, and the Z-axis direction is vertical.

[0024] As shown in FIG. 1, the laser processing apparatus 200 forms a modified region in the object 1 by irradiating the object 1 with laser light. The object 1 is a plate-like member (e.g., a substrate, a wafer, etc.) including a semiconductor substrate made of a semiconductor material or a piezoelectric substrate made of a piezoelectric material. As shown in FIG. 2, a line to cut 5 for cutting the object 1 is set on the object 1. The line to cut 5 is a virtual line extending linearly. When forming a modified region inside the object 1, the laser light is moved relatively along the line to cut 5 while the focal point (at least a part of the focal region) is aligned inside the object 1. As a result, a modified region is formed in the object 1 along the line to cut 5.

[0025] The lines 5 to cut are not limited to straight lines but may be curved lines, may be three-dimensional lines that combine these, or may be coordinate-specified lines. The lines 5 to cut are not limited to imaginary lines but may be lines that are actually drawn on the surface of the object 1. The modified regions may be formed continuously or intermittently. The modified regions may be in the form of rows or dots, and the point is that the modified regions only need to be formed inside the object 1. In addition, cracks may be formed starting from the modified regions, and the cracks and modified regions may be exposed on the outer surface (front surface, back surface, or outer peripheral surface) of the object 1. The laser light incident surface when forming the modified regions is not limited to the front surface of the object 1, but may also be the back surface of the object 1.

[0026] A modified region is a region in which the density, refractive index, mechanical strength, or other physical properties are different from those of the surrounding area. Examples of modified regions include melt-processed regions (meaning at least one of a region that has been melted and then re-solidified, a region in a molten state, and a region in the process of re-solidifying from a melt), crack regions, dielectric breakdown regions, and refractive index change regions, as well as mixtures of these. Modified regions include regions in the material of object 1 where the density of the modified region has changed compared to the density of a non-modified region, and regions where lattice defects have formed. When the material of object 1 is single-crystal silicon, the modified region can also be referred to as a high-dislocation density region.

[0027] 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 unmodified region, and the region where lattice defects have formed may further contain cracks (fractures, microcracks) within these regions or at the interface between the modified region and the unmodified region. The contained cracks may extend across the entire modified region, or may form in only a portion or multiple portions. The object 1 includes a substrate made of a crystalline material having a crystalline structure. For example, the object 1 includes a substrate made of at least one of gallium nitride (GaN), silicon (Si), silicon carbide (SiC), LiTaO3, and sapphire (Al2O3). In other words, the object 1 includes, for example, a gallium nitride substrate, a silicon substrate, a SiC substrate, a LiTaO3 substrate, or a sapphire substrate. The crystalline material may be either an anisotropic crystal or an isotropic crystal. Furthermore, the object 1 may include a substrate made of a non-crystalline material having a non-crystalline structure (amorphous structure), and may include, for example, a glass substrate.

[0028] In an embodiment, a modified region can be formed by forming a plurality of modified spots (processing marks) along the line to cut 5. In this case, a plurality of modified spots gather to form a modified region. A modified spot is a modified portion formed by one pulse of pulsed laser light (i.e., one pulse of laser irradiation: laser shot). Examples of modified spots include crack spots, melting spots, refractive index change spots, or a mixture of at least one of these. The size of the modified spots and the length of the cracks that occur can be appropriately controlled taking into account the required cutting accuracy, the required flatness of the cut surface, the thickness, type, and crystal orientation of the object 1, etc. In an embodiment, modified spots can be formed as modified regions along the line to cut 5.

[0029] 1, 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.

[0030] The first movement mechanism 220 is attached to the device frame 210. The first movement mechanism 220 has a first rail unit 221, a second rail unit 222, and a movable base 223. The first rail unit 221 is attached to the device frame 210. The first rail unit 221 is provided with a pair of rails 221a, 221b extending along the Y-axis direction. The second rail unit 222 is attached to the pair of rails 221a, 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, 222b extending along the X-axis direction. The movable base 223 is attached to the pair of rails 222a, 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.

[0031] The support table 230 is attached to the movable base 223. The support table 230 supports the target object 1. In the example shown in FIG. 2, the target object 1 is, for example, a substrate made of a semiconductor material such as silicon, on the surface of which a plurality of functional elements (light-receiving elements such as photodiodes, light-emitting elements such as laser diodes, or circuit elements formed as a circuit, etc.) are formed in a matrix. When the target object 1 is supported on the support table 230, for example, the back surface 1b of the target object 1, opposite to the front surface 1a (the surface on which the plurality of functional elements are located) is attached to a film 12 attached to an annular frame 11. The support table 230 supports the target object 1 by holding the frame 11 with a clamp and adsorbing the film 12 with a vacuum chuck table. On the support table 230, a plurality of parallel cutting lines 5a and a plurality of parallel cutting lines 5b are set in a grid pattern on the target object 1 so as to pass between adjacent functional elements.

[0032] 1, the support base 230 is moved along the Y-axis direction by operation of the second rail unit 222 in the first movement mechanism 220. The support base 230 is moved along the X-axis direction by operation of the movable base 223 in the first movement mechanism 220. The support base 230 is further rotated about an axis parallel to the Z-axis direction by operation of the movable base 223 in the first movement mechanism 220. In this way, the support base 230 is attached to the apparatus frame 210 so as to be movable along the X-axis direction and the Y-axis direction and rotatable about an axis parallel to the Z-axis direction.

[0033] The laser output unit 300 is attached to the device frame 210. The laser focusing unit 400 is attached to the device frame 210 via a second movement mechanism 240. The laser focusing unit 400 is moved along the Z-axis direction (the optical axis direction of the focusing lens unit 430, which will be described later) by operation of the second movement mechanism 240. In this way, the laser focusing unit 400 is attached to the device frame 210 so as to be movable along the Z-axis direction relative to the laser output unit 300.

[0034] The control unit 500 is configured with 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 part of the laser processing apparatus 200. The processing by the control unit 500 will be described in detail later.

[0035] In the laser processing apparatus 200, modified regions are formed inside the object 1 along each of the lines to cut 5a, 5b, for example, as follows. First, the object 1 is supported on the support table 230 so that the front surface 1a of the object 1 is the incident surface of the laser light, and each of the lines to cut 5a of the object 1 is aligned parallel to the X-axis direction. Alignment (so-called height setting) is performed to align the position of the focusing lens unit 430 (described below) in the Z-axis direction with the incident surface to a reference position. The second moving mechanism 240 moves the laser focusing unit 400 in the Z-axis direction so that the focal point of the laser light L inside the object 1 is located a predetermined distance away from the incident surface. While maintaining a constant distance between the incident surface and the focal point of the laser light L, the focal point of the laser light L is moved relatively along each of the lines to cut 5a. This forms modified regions inside the object 1 along each of the lines to cut 5a. The incident surface is not limited to the front surface 1a and may be the back surface 1b.

[0036] When the formation of the modified regions along each of the lines to cut 5a has been completed, the support table 230 is rotated by the first moving mechanism 220, and each of the lines to cut 5b on the object 1 is aligned parallel to the X-axis direction. The height is set. The second moving mechanism 240 moves the laser focusing unit 400 so that the focal point of the laser light L inside the object 1 is located at a predetermined distance from the laser light incident surface. While maintaining a constant distance between the laser light incident surface and the focal point of the laser light L, the focal point of the laser light L is moved relatively along each of the lines to cut 5b. This forms modified regions inside the object 1 along each of the lines to cut 5b.

[0037] As described above, in the laser processing device 200, the direction parallel to the X-axis direction is set as the processing direction (the scanning direction of the laser light L). The relative movement of the focal point of the laser light L along each of the lines to cut 5a and the relative movement of the focal point of the laser light L along each of the lines to cut 5b is achieved by moving the support table 230 along the X-axis direction by the first moving mechanism 220. The relative movement of the focal point of the laser light L between each of the lines to cut 5a and the relative movement of the focal point of the laser light L between each of the lines to cut 5b is achieved by moving the support table 230 along the Y-axis direction by the first moving mechanism 220.

[0038] 3, the laser output unit 300 includes a mounting base 301, a cover 302, and a plurality of mirrors 303 and 304. The laser output unit 300 further 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 polarizer unit (output adjustment unit, polarization direction adjustment unit) 340, a beam expander (laser light collimator) 350, and a mirror unit 360.

[0039] The mounting base 301 supports a plurality of 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 mirror unit 360. The plurality of 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 mirror unit 360 are attached to a main surface 301a of the mounting base 301. The mounting base 301 is a plate-shaped member, and is detachable from the device frame 210 (see FIG. 1 ). The laser output unit 300 is attached to the device frame 210 via the mounting base 301. That is, the laser output unit 300 is detachable from the device frame 210.

[0040] 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 detachable from the mounting base 301.

[0041] 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 within 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, for example, sapphire. The laser light L in each of the wavelength bands of 1000 to 1150 nm and 1300 to 1400 nm is suitable for internal absorption laser processing of substrates made of, for example, silicon. 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 mirror 303 and enters the shutter 320 along the Y-axis direction.

[0042] In the laser oscillator 310, the output of the laser light L is switched on / off as follows: When the laser oscillator 310 is configured with a solid-state laser, the output of the laser light L is switched on / off at high speed by switching on / off a Q switch (such as an AOM (acousto-optic modulator) or an EOM (electro-optic modulator)) provided in the resonator. When the laser oscillator 310 is configured with a fiber laser, the output of the laser light L is switched on / off at high speed by switching on / off the outputs of semiconductor lasers that constitute the seed laser and amplifier (excitation) laser. When the laser oscillator 310 uses an external modulation element, the output of the laser light L is switched on / off at high speed by switching on / off an external modulation element (such as an AOM or EOM) provided outside the resonator.

[0043] The shutter 320 uses a mechanical mechanism to open and close the optical path of the laser light L. As described above, the output of the laser light L from the laser output unit 300 is switched on and off by switching on and off the output of the laser light L in the laser oscillator 310, but the provision of the shutter 320 prevents, for example, the laser light L from being accidentally emitted from the laser output unit 300. The laser light L that passes through the shutter 320 is reflected by the mirror 304 and sequentially enters the λ / 2 wave plate unit 330 and the polarizing plate unit 340 along the X-axis direction.

[0044] 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. In addition, 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 will be described in detail later. The laser light L that has passed through the λ / 2 wave plate unit 330 and the polarizing plate unit 340 in sequence is incident on the beam expander 350 along the X-axis direction.

[0045] The beam expander 350 adjusts the diameter of the laser light L and collimates the laser light L. The laser light L that has passed through the beam expander 350 is incident on the mirror unit 360 along the X-axis direction.

[0046] The mirror unit 360 has a support base 361 and multiple mirrors 362 and 363. The support base 361 supports the multiple mirrors 362 and 363. The support base 361 is attached to the mounting base 301 so that its position is adjustable along the X-axis and Y-axis directions. The mirror 362 reflects the laser light L that has passed through the beam expander 350 in the Y-axis direction. The mirror 362 is attached to the support base 361 so that the angle of its reflective surface is adjustable, for example, around an axis parallel to the Z-axis. The mirror 363 reflects the laser light L reflected by the mirror 362 in the Z-axis direction. The mirror 363 is attached to the support base 361 so that the angle of its reflective surface is adjustable, for example, around an axis parallel to the X-axis and its position is adjustable along the Y-axis direction. The laser light L reflected by the mirror 363 passes through an opening 361a formed in the support base 361 and enters the laser focusing unit 400 (see FIG. 1) along the Z-axis direction. In other words, the emission direction of the laser light L from the laser output unit 300 coincides with the movement direction of the laser focusing unit 400. As described above, each mirror 362, 363 has a mechanism for adjusting the angle of the reflecting surface. In the mirror unit 360, the position of the support base 361 relative to the mounting base 301, the position of the mirror 363 relative to the support base 361, and the angle of the reflecting surface of each mirror 362, 363 are adjusted, so that the position and angle of the optical axis of the laser light L emitted from the laser output unit 300 are aligned with the laser focusing unit 400. In other words, the multiple mirrors 362, 363 are configured to adjust the optical axis of the laser light L emitted from the laser output unit 300.

[0047] As shown in FIG. 4, the laser focusing unit 400 has a housing 401. The housing 401 has a rectangular parallelepiped shape with the Y-axis direction as the longitudinal direction. A second movement mechanism 240 is attached to one side surface 401e of the housing 401 (see FIGS. 5 and 7). A cylindrical light incident portion 401a is provided in the housing 401 so as to face the opening 361a of the mirror unit 360 in the Z-axis direction. The light incident portion 401a causes the laser light L emitted from the laser output unit 300 to enter the housing 401. The mirror unit 360 and the light incident portion 401a are spaced apart from each other by a distance that prevents them from coming into contact with each other when the laser focusing unit 400 is moved along the Z-axis direction by the second movement mechanism 240.

[0048] 5 and 6, the laser focusing unit 400 has a mirror 402 and a dichroic mirror 403. Furthermore, the laser focusing unit 400 has a reflective spatial light modulator (spatial light modulator) 410, a 4f lens unit 420, a focusing lens unit 430, a drive mechanism 440, and a pair of separate axis distance measuring sensors (displacement information acquisition units) 450. The laser focusing unit 400 irradiates the target 1 with laser light L via the focusing lens unit 430.

[0049] The mirror 402 is attached to the bottom surface 401b of the housing 401 so as to face the light incident unit 401a in the Z-axis direction. The mirror 402 reflects the laser light L that enters the housing 401 through the light incident unit 401a in a direction parallel to the XY plane. The laser light L that has been collimated by the beam expander 350 of the laser output unit 300 is incident on the mirror 402 along the Z-axis direction. That is, the laser light L is incident on the mirror 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 movement mechanism 240, the state of the laser light L that enters the mirror 402 along the Z-axis direction is maintained constant. The laser light L reflected by the mirror 402 is incident on the reflective spatial light modulator 410.

[0050] The reflective spatial light modulator 410 is attached to an end 401c of the housing 401 in the Y-axis direction, with a reflective surface 410a facing the inside of the housing 401. The reflective spatial light modulator 410 is, for example, a reflective liquid crystal on silicon (LCOS) spatial light modulator (SLM), and reflects the laser light L in the Y-axis direction while modulating the laser light L. The laser light L modulated and reflected by the reflective spatial light modulator 410 is incident on 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 (for example, 10 to 60°). That is, 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 prevent a decrease in diffraction efficiency, and to allow the reflective spatial light modulator 410 to fully exhibit its performance.

[0051] The 4f lens unit 420 has 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 member 424. The holder 421 holds the pair of lenses 422, 423 and the slit member 424. The holder 421 maintains a constant positional relationship between the pair of lenses 422, 423 and the slit member 424 in the direction along the optical axis of the laser light L. The pair of lenses 422, 423 configure a double-telecentric optical system in which a reflecting surface 410a of the reflective spatial light modulator 410 and an entrance pupil plane 430a of the condenser lens unit 430 are in an imaging relationship. As a result, an image of the laser light L on the reflecting surface 410a of the reflective spatial light modulator 410 (an image of the laser light L modulated by the reflective spatial light modulator 410) is transferred (imaged) on an 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, near the focal plane of the lens 422. An unnecessary portion of the laser light L that has been modulated and reflected by the reflective spatial light modulator 410 is blocked by the slit member 424. The laser light L that has passed through the 4f lens unit 420 is incident on the dichroic mirror 403 along the Y-axis direction.

[0052] Dichroic mirror 403 reflects most of the laser light L (e.g., 95 to 99.5%) in the Z-axis direction and transmits a portion of the laser light L (e.g., 0.5 to 5%) along the Y-axis direction. Most of the laser light L is reflected at a right angle along the ZX plane by dichroic mirror 403. The laser light L reflected by dichroic mirror 403 enters condenser lens unit 430 along the Z-axis direction.

[0053] Condenser lens unit 430 is attached to end 401d of housing 401 in the Y-axis direction (the end opposite end 401c) via drive mechanism 440. Condenser lens unit 430 has a holder 431 and a plurality of condenser lenses 432. Holder 431 holds the plurality of condenser lenses 432. The plurality of condenser lenses 432 condense laser light L onto target object 1 (see FIG. 1) supported by support base 230. Drive mechanism 440 moves condenser lens unit 430 along the Z-axis direction using the driving force of a piezoelectric element.

[0054] The separate-axis distance measuring sensor 450 is attached to the end 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 separate-axis distance measuring sensor 450 uses a first measurement laser beam (measurement laser beam) to acquire first displacement information that changes according to the displacement of the incident surface of the laser beam of the object 1 (see FIG. 1). The separate-axis distance measuring sensor 450 emits the first measurement laser beam to the incident surface of the object 1 (see FIG. 1) supported by the support base 230, and receives the first measurement laser beam reflected by the incident surface, thereby acquiring the first displacement information according to the displacement of the incident surface of the object 1. Note that the separate-axis distance measuring sensor 450 can be a sensor using a triangulation method, a laser confocal method, a white light confocal method, a spectral interference method, an astigmatism method, or the like.

[0055] The laser focusing unit 400 has 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 that has passed through the dichroic mirror 403 into a reflected component and a transmitted component. The laser light L reflected by the beam splitter 461 is sequentially incident on the pair of lenses 462 and 463 and the camera 464 along the Z-axis direction. The pair of lenses 462 and 463 form a double-telecentric optical system in which an entrance pupil plane 430a of the focusing lens unit 430 and an imaging plane of the camera 464 are in an imaging relationship. As a result, the image of the laser light L on the entrance pupil plane 430a of the focusing lens unit 430 is transferred (imaged) on the imaging plane of the camera 464. As described above, the image of the laser light L on the entrance pupil plane 430a of the condenser lens unit 430 is an image of the laser light L modulated by the reflective spatial light modulator 410. Therefore, in the laser processing apparatus 200, by monitoring the imaging results by the camera 464, the operating state of the reflective spatial light modulator 410 can be grasped.

[0056] Furthermore, the laser focusing unit 400 has 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 separates the laser light L that 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 sequentially incident on the lens 472 and the camera 473 along the Z-axis direction. The lens 472 focuses the incident laser light L on the imaging surface of the camera 473.

[0057] The multiple beam splitters 461, 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, 463 are disposed within a cylindrical body 405 erected on the cylindrical body 404 along the Z-axis direction, and a camera 464 is disposed at the end of the cylindrical body 405. The lens 472 is disposed within a cylindrical body 406 erected on the cylindrical body 404 along the Z-axis direction, and 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. The laser light L transmitted through the beam splitter 471 may be absorbed by a damper or the like provided at the end of the cylindrical body 404, or may be used for an appropriate purpose.

[0058] 6 and 7, the laser focusing unit 400 includes a visible light source 481, multiple lenses 482, a reticle 483, a mirror 484, a half mirror 485, a beam splitter 486, a lens 487, an observation camera (imaging unit) 488, and a coaxial distance measuring sensor 460. The visible light source 481 emits visible light V along the Z-axis direction. The multiple lenses 482 collimate the visible light V emitted from the visible light source 481. The reticle 483 imparts a mark to the visible light V. The mirror 484 reflects the visible light V collimated by the multiple lenses 482 in the X-axis direction. The half mirror 485 separates the visible light V reflected by the mirror 484 into a reflected component and a transmitted component. The visible light V reflected by the half mirror 485 passes through the beam splitter 486 and the dichroic mirror 403 sequentially along the Z-axis direction, and is irradiated onto the object 1 (see Figure 1) supported on the support stand 230 via the focusing lens unit 430.

[0059] The visible light V irradiated onto the object 1 is reflected by the laser light incident surface of the object 1, enters the dichroic mirror 403 via the condenser lens unit 430, and transmits through the dichroic mirror 403 along the Z-axis direction. The beam splitter 486 separates the visible light V transmitted through the dichroic mirror 403 into a reflected component and a transmitted component. The beam splitter 486 also reflects a second measurement laser beam L2 and its reflected light L2R (described below). The visible light V transmitted through the beam splitter 486 passes through a half mirror 485 and sequentially enters a lens 487 and an observation camera 488 along the Z-axis direction. The lens 487 condenses the incident visible light V onto the imaging surface of the observation camera 488. The observation camera 488 captures an image of the laser light incident surface of the object 1. Observation camera 488 receives visible light V that is incident on the laser light incident surface through reticle 483 and reflected by the laser light incident surface. In laser processing apparatus 200, the state of object 1 can be grasped by observing the imaging results by observation camera 488.

[0060] The mirror 484, the half mirror 485, and the beam splitter 486 are disposed in a holder 407 attached to the end 401d of the housing 401. The plurality of lenses 482 and the reticle 483 are disposed in a cylinder 408 erected on the holder 407 along the Z-axis direction, and the visible light source 481 is disposed at the end of the cylinder 408. The lens 487 is disposed in a cylinder 409 erected on the holder 407 along the Z-axis direction, and the observation camera 488 is disposed at the end of the cylinder 409. The cylinders 408 and 409 are arranged side by side in the X-axis direction. Note that the visible light V transmitted through the half mirror 485 along the X-axis direction and the visible light V reflected in the X-axis direction by the beam splitter 486 may be absorbed by a damper or the like provided on the wall of the holder 407, or may be used for an appropriate purpose.

[0061] The coaxial distance measuring sensor 460 (displacement information acquisition unit) is attached to the side of the holder 407. The coaxial distance measuring sensor 460 emits a second measurement laser beam L2 (measurement laser beam) toward the laser beam incident surface of the object 1 (see FIG. 1) supported by the support base 230, and detects reflected light L2R of the second measurement laser beam L2 reflected by the laser beam incident surface to acquire first displacement information corresponding to the displacement of the laser beam incident surface of the object 1. The second measurement laser beam 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 condenser lens unit 430, where it is reflected by the laser beam incident surface near the focal point of the condenser lens unit 430. The reflected light L2R returns to the coaxial distance measuring sensor 460 via a path opposite to that of the second measurement laser beam L2. The coaxial distance measuring sensor 460 acquires first displacement information of the target object 1 by utilizing the fact that the state of the reflected light L2R changes depending on the position of the laser light incident surface relative to the condenser lens unit 430. For example, the coaxial distance measuring sensor 460 can be an astigmatism type sensor or the like.

[0062] 8, the separate-axis distance measuring sensor 450 includes a light-emitting element 451, such as a laser diode, that emits a first measurement laser beam L1, and a linear photodiode array (light-receiving element array) 453 that receives the first measurement laser beam L1 reflected by the laser beam incident surface of the object 1. The separate-axis distance measuring sensor 450 is a triangulation sensor that uses a triangulation method. The laser beam incident surface here is the surface 1a of the object 1 (see FIG. 2).

[0063] In the separate-axis distance measuring sensor 450, a first measurement laser beam L1 is emitted from a light-emitting element 451 in a direction inclined with respect to the Z-axis direction. The emitted first measurement laser beam L1 is focused toward the object 1 via a lens 452 and reflected by the laser beam incident surface. The reflected first measurement laser beam L1 travels in a direction inclined with respect to the Z-axis direction, is focused toward a linear photodiode array 453 via a lens 454, and is received at a spot position SP of the linear photodiode array 453.

[0064] A spot position SP (hereinafter simply referred to as "spot position SP"), which is the position of light reception on the linear photodiode array 453, has a unique relationship with the displacement of the laser light incident surface. As a result, the separate axis distance measuring sensor 450 acquires spot position information (light reception position information) corresponding to the spot position (light reception position) SP as first displacement information. A plurality of linear photodiode arrays 453 may be provided.

[0065] Based on the imaging result by the observation camera 488, the control unit 500 operates the second moving mechanism 240 to move the laser focusing unit 400 in the Z-axis direction, and executes a first alignment process to align the position of the focusing lens unit 430 (focusing lens 432) in the Z-axis direction with respect to the laser light incident surface to an initial height position. When the control unit 500 aligns the focusing lens unit 430 to the initial height position by the first alignment process, the control unit 500 records information on the initial spot position SP0, which is the spot position SP acquired by the separate-axis distance measuring sensor 450, in the storage unit of the control unit 500 as initial spot position information.

[0066] 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 in focus on the image of the laser light incident surface captured by the observation camera 488 (hereinafter also referred to as the "reticle focus position") (see FIG. 9). Here, the optical system is adjusted so that the mark of the reticle 483 is in focus on the laser light incident surface. In other words, the reticle focus position is the position of the condenser lens unit 430 in the Z-axis direction when the focal point of the condenser lens unit 430 is aligned with the laser light incident surface.

[0067] Note that, when the optical system is adjusted so that the focus of the mark on the reticle 483 is not on the laser light incident surface but at a height position a predetermined distance away from the laser light incident surface, the position at which the mark on the reticle 483 is in focus is not on the laser light incident surface but at that height position a predetermined distance away from the laser light incident surface. If, as a result of executing the first positioning process, the control unit 500 cannot recognize a state in which the mark on the reticle 483 is in focus on the image of the laser light incident surface captured by the observation camera 488, the control unit 500 executes a process that determines that the target object 1 cannot be processed.

[0068] The control unit 500 executes a light-receiving amount adjustment process to adjust the separate-axis distance measuring sensor 450 so that the amount of light received by the linear photodiode array 453 is equal to or greater than a threshold. Examples of adjustments to the separate-axis distance measuring sensor 450 include increasing at least one of the gain and the exposure time, and increasing the output of the light-emitting element 451.

[0069] Next, an example of laser processing performed by the above-mentioned laser processing apparatus 200 will be described. FIG. 10 is a schematic diagram showing an enlarged portion of the object shown in FIG. 2. As shown in FIG. 10, the object 1 is supported by the support table 230 in a state where the lines to cut 5a are parallel to the X-axis direction (first processing state). On the other hand, as shown in FIG. 20, the object 1 may be supported by the support table 230 in a state where the lines to cut 5b are parallel to the X-axis direction (second processing state). As shown in FIG. 10, the surface 1a of the object 1, which is the incident surface of the laser light L, includes device regions DR corresponding to functional elements. The device regions DR are arranged two-dimensionally along the X-axis direction and the Y-axis direction in accordance with the arrangement of the functional elements.

[0070] Furthermore, in the first processing state, the surface 1a includes a plurality of first street regions SR1 which are regions between adjacent device regions DR along the Y-axis direction (second direction in the first processing state) and extend along the X-axis direction (first direction in the first processing state), and a plurality of second street regions SR2 which are regions between adjacent device regions DR along the X-axis direction and extend along the Y-axis direction. In this example, the line to cut 5a along which the laser light L is scanned is set at the center of the first street region SR1, and another line to cut 5b along which the laser light L is scanned is set at the center of the second street region SR2. Here, first, a case will be described in which the laser light L is scanned over the first street region SR1 and the separate axis distance measuring sensor 450 is used.

[0071] In this case, in order to obtain first displacement information corresponding to the displacement of the surface 1 a in the Z-axis direction in the first street region SR1 (i.e., first displacement information indicating the displacement of the first street region SR1 in the Z-axis direction), the first measurement laser beam L1 is also scanned over the first street region SR1 by the separate axis distance measuring sensor 450. Here, the width of the first street region SR1 in the Y-axis direction is narrower than the spot size of the first measurement laser beam L1 on the surface 1 a. The spot size of the first measurement laser beam L1 on the surface 1 a refers to the spot diameter of the first measurement laser beam L1 on the surface 1 a when, for example, the laser focusing unit 400 is moved along the Z-axis direction by the second moving mechanism 240 to align the focusing point of the laser beam L with a desired processing position inside the target object 1 in the Z-axis direction.

[0072] FIG. 11 is a graph showing an example of first displacement information acquired by the other-axis distance measuring sensor. In each graph in FIG. 11, the horizontal axis represents time (i.e., position in the X-axis direction) and the vertical axis represents voltage values ​​indicating displacement. (a) of FIG. 11 shows first displacement information DSa when the width of the first street region SR1 is 15 μm and the spot diameter of the first measurement laser beam L1 is 20 μm. (b) of FIG. 11 shows first displacement information DSb when the width of the first street region SR1 is 15 μm and the spot diameter of the first measurement laser beam L1 is 15 μm. (c) of FIG. 11 shows first displacement information DSc when the width of the first street region SR1 is 15 μm and the spot diameter of the first measurement laser beam L1 is 10 μm.

[0073] 11(c) is the case where the spot diameter of the first measurement laser beam L1 is smaller than the width of the first street region SR1, so it is considered that the first displacement information DSc contains relatively little noise caused by the first measurement laser beam L1 being irradiated onto the device region DR and more accurately represents the actual displacement of the first street region SR1. In contrast, the first displacement information DSa shown in FIG. 11(a) is the case where the width of the first street region SR1 is narrower than the spot diameter of the first measurement laser beam L1, so that when the first street region SR1 is scanned with the first measurement laser beam L1, part of the first measurement laser beam L1 is also irradiated onto the device region DR, and therefore contains a lot of noise due to the influence of the device region DR (for example, shielding or reflection).

[0074] Therefore, in this case, the waveform of the first displacement information DSa will differ from the actual displacement of the surface 1a in the first street region SR1, which may reduce the accuracy of tracking the focal point of the laser light L based on the first displacement information DSa. Therefore, the laser processing according to this embodiment suppresses such a reduction in the accuracy of tracking the focal point of the laser light L. Note that the first displacement information DSb shown in FIG. 11(b) has less noise than the first displacement information DSa, and its waveform is closer to that of the first displacement information DSc.

[0075] Fig. 12 is a flowchart showing the laser processing method according to this embodiment. Each step of the laser processing method shown in Fig. 12 corresponds to each process performed by the control unit 500 (i.e., each operation of the laser processing apparatus 200).

[0076] 12, first, the control unit 500 registers a pattern of the surface 1a of the object 1, which is the incident surface of the laser light L (step S101). Next, the control unit 500 determines positions to scan with the laser light L and the first measurement laser light L1 based on the pattern registered in step S101 (step S102). Here, the position of the first street region SR1 is determined.

[0077] Next, the control unit 500 controls the other-axis distance measuring sensor 450 to acquire first displacement information corresponding to the displacement of the first street region SR1 (step S103, first acquisition step). More specifically, as shown in Figures 13 and 14, in step S103, the control unit 500 first controls the first moving mechanism 220 to rotate the support base 230, thereby establishing a first processing state in which the first street region SR1 (i.e., the line to cut 5a) determined in step S102 is parallel to the X-axis direction. In this state, the control unit 500 positions the spot of the first measurement laser beam L1 in the first street region SR1.

[0078] Thereafter, the control unit 500 controls the separate-axis distance measuring sensor 450 to irradiate the first measurement laser beam L1, while controlling the first moving mechanism 220 to move the support base 230 along the X-axis direction. This causes the control unit 500 to scan the first street region SR1 with the first measurement laser beam L1. As a result, the separate-axis distance measuring sensor 450 receives the first measurement laser beam L1 reflected from the surface 1a, thereby obtaining first displacement information DS1 (see FIG. 15(a)) indicating the displacement of the surface 1a in the first street region SR1.

[0079] In this way, in step S103, the control unit 500 performs a first acquisition process in which the separate axis distance measuring sensor 450 acquires first displacement information DS1 in the first street area SR1 by scanning the first measurement laser light L1 over the first street area SR1. Here, the first moving mechanism 220 is a moving mechanism that moves the irradiation area (spot) of the first measurement laser light L1 on the surface 1a of the object 1 relative to the object 1.

[0080] The first street region SR1 includes an intersection CR with the second street region SR2. Therefore, the first displacement information DS1 acquired here includes multiple intersection information corresponding to the intersections CR that appear in the first street region SR1 at a predetermined pitch (the spacing between device regions DR in the X-axis direction). Figure 15(a) shows the first displacement information DS1 acquired in step S103.

[0081] In the next step, the control unit 500 analyzes the first displacement information D1 acquired in step S103 (step S104, second acquisition step). More specifically, in step S104, the control unit 500 first estimates the position of the intersection CR between the first street region SR1 and the second street region SR2 based on the concave and convex shape of the waveform of the first displacement information D1. The concave and convex shape of the waveform of the first displacement information DS1 tends to protrude at the intersection CR, forming a protrusion P. Therefore, here, as shown in FIG. 15(b), the control unit 500 estimates the protrusion P of the concave and convex shape of the waveform of the first displacement information DS1 as the position of the intersection CR. At the same time, the control unit 500 extracts intersection information, which is the displacement value (height in the Z-axis direction) at the estimated position of the intersection CR, from the first displacement information DS1.

[0082] Next, as shown in (c) of Figure 15, the control unit 500 interpolates (e.g., linearly interpolates) the intersection information extracted in step S104 in the X-axis direction to obtain second displacement information DS2 from the first displacement information DS1 (step S105, second acquisition step).

[0083] In this way, in steps S104 and S105, the second displacement information DS2 is acquired based on the first displacement information DS1 acquired in step S103. That is, in steps S104 and S105, the control unit 500 extracts, from the first displacement information DS1 acquired in step S103, a plurality of pieces of intersection information corresponding to the intersection CR between the first street region SR1 and the second street region SR2, and interpolates the extracted plurality of pieces of intersection information in the X-axis direction (the first direction in the first processing state), thereby performing a second acquisition process to acquire second displacement information DS2 corresponding to the displacement of the first street region SR1.

[0084] Fig. 16 is a graph showing an example of the first displacement information, intersection information, and second displacement information. Fig. 16(a) shows an example of the first displacement information DS1 acquired in step S103, Fig. 16(b) shows an example of the intersection information DS1c extracted in step S104, and Fig. 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 measurement laser beam L1 is smaller than the width of the first street region SR1.

[0085] 16, the first displacement information DS1 contains a lot of noise caused by part of the first measurement laser light L1 being irradiated onto the device region DR, whereas the second displacement information DS2 obtained by interpolating the intersection information DS1c sufficiently matches the first displacement information DSc, which is considered to more accurately represent the actual displacement of the first street region SR1. In other words, the second displacement information DS2 is considered to more accurately reflect the actual displacement of the first street region SR1 than the first displacement information DS1.

[0086] 17, the pitch Pc (period) of the intersections CR in the first displacement information DS1 changes depending on the chip size of the object 1, i.e., the size of the device region DR. In addition, the example in Fig. 15 illustrates a case where the protrusions P indicating the intersections CR in the first displacement information DS1 are convex downward (toward the smaller displacement), but as shown in Fig. 18, there are also cases where the protrusions P indicating the intersections CR in the first displacement information DS1 are convex upward (toward the larger displacement).

[0087] 19, the control unit 500 performs follow-up processing of the laser light L based on the second displacement information (step S106, processing step). More specifically, in step S106, the focus point of the laser light L is positioned in the first street region SR1 for which the second displacement information DS2 has been acquired in steps 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 controlling the first moving mechanism 220 to move the support base 230 along the X-axis direction. This causes the laser light L to scan the first street region SR1.

[0088] At this time, the control unit 500 controls the drive mechanism 440 to move the condenser lens unit 430 along the Z-axis based on the second displacement information DS2 (i.e., in accordance with the displacement of the first street region SR1 in the Z-axis direction), thereby maintaining a constant distance between the focal point of the laser light L and the surface 1a of the object 1. This allows laser processing of the object 1 to be performed by irradiating the laser light L along the line to cut 5a set in the first street region SR1 and following the displacement of the surface 1a. As a result, a modified region is formed in the object 1 along the line to cut 5a in the first street region SR1, and the series of processes is completed.

[0089] In this way, in step S106, the target object 1 is scanned with the laser light L to form a modified region in the target object 1. That is, in step S106, the control unit 500 performs a first processing process to form a modified region in the target object 1 by scanning the first street region SR1 with the laser light L while adjusting the position of the focal point of the laser light L in the Z-axis direction that intersects with the surface 1a, which is the incident surface of the laser light L of the target object 1, based on the second displacement information. Here, the first moving mechanism 220 and the driving mechanism 440 are moving mechanisms that move the focal point of the laser light L relative to the target object 1.

[0090] In this embodiment, the scanning with the first measurement laser light L1 in step S103 and the scanning with the laser light L in step S106 are performed in a partially overlapping manner. That is, since the separate-axis distance measuring sensor 450 is used in step S103, the scanning with the first measurement laser light L1 is started in a state where the separate-axis distance measuring sensor 450 is positioned ahead of the laser focusing unit 400 in the scanning direction (X-axis direction) of the first measurement laser light L1 and the laser light L.

[0091] As a result, the 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. Then, based on the sequentially generated second displacement information DS2, the control unit 500 performs scanning with the laser light L while adjusting the position of the focal point of the following laser light L. This makes it possible to perform follow-up processing while acquiring information indicating the displacement of the first street region SR1.

[0092] By performing the above steps S103 to S106 on all of the first street regions SR1, the formation of modified regions along all of the lines to cut 5a is completed.

[0093] As described above, in the laser processing apparatus 200 and the laser processing method according to this embodiment, the separate-axis distance measuring sensor 450 irradiates the surface 1a, which is the laser light incident surface of the object 1, with the first measurement laser beam L1 and receives the reflected light of the first measurement laser beam L1 from the surface 1a, thereby acquiring first displacement information DS1 according to the displacement of the surface 1a. Therefore, based on this first displacement information DS1, it is possible to scan the laser beam L while causing the focal point of the laser beam L to follow the displacement of the surface 1a.

[0094] In particular, the object 1 includes, on its surface 1a, a plurality of device regions DR arranged along the X-axis and Y-axis directions that intersect with each other, a plurality of first street regions SR1 that are regions between the device regions DR and extend along the X-axis direction, and a plurality of second street regions SR2 that are regions between the device regions DR and extend along the Y-axis direction. When acquiring the first displacement information DS1, the first street region SR1 is scanned with a first measurement laser beam L1. Therefore, there is a risk that noise in the first displacement information DS1 will increase due to the first measurement laser beam L1 also being irradiated onto the device regions DR.

[0095] In contrast, in the laser processing apparatus 200 and laser processing method according to this embodiment, multiple pieces of intersection information DS1c corresponding to the intersections CR between the first street region SR1 and the second street region SR2 are extracted from the first displacement information DS1, and second displacement information DS2 corresponding to the displacement of the first street region SR1 is acquired by interpolating the extracted multiple pieces of intersection information DS1c. Then, based on the second displacement information DS2, the laser light L is scanned over the first street region SR1 while adjusting the position of the focal point of the laser light L in the Z-axis direction intersecting with the surface 1a, thereby forming a modified region in the target object 1.

[0096] At the intersection CR between the first street region SR1 and the second street region SR2, there is no device region DR in the Y-axis direction, which is the width direction of the first street region SR1 (i.e., the second street region SR2 extends in the Y-axis direction), so the first measurement laser beam L1 is less likely to be irradiated onto the device region DR than in regions of the first street region SR1 other than the intersection CR. Therefore, the intersection information DS1c corresponding to the intersection CR in the first displacement information DS1 contains relatively little noise caused by the first measurement laser beam L1 being irradiated onto the device region DR.

[0097] Therefore, the second displacement information DS2 obtained by interpolating the multiple intersection 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 street region SR1. Therefore, by using this second displacement information DS2 when forming a modified region in the target object 1, it is possible to suppress a decrease in the tracking accuracy of the focal point of the laser light L in the Z-axis direction.

[0098] In particular, in this embodiment, the width of the first street region SR1 in the Y-axis direction is narrower than the spot diameter of the first measurement laser beam L1 on the surface 1a. Therefore, as described above, a portion of the first measurement laser beam L1 is more likely to be irradiated onto the device region DR. Therefore, the influence of noise in the first displacement information DS1 becomes greater in the region of the first street region SR1 other than the intersection CR with the second street region SR2. Therefore, it is more advantageous to use the second displacement information DS2 obtained by interpolating the intersection information DS1c, which has relatively less noise, from the first displacement information DS1.

[0099] Furthermore, in the laser processing apparatus 200 according to this embodiment, the control unit 500 estimates the position of the intersection CR between the first street region SR1 and the second street region SR2 based on the concave-convex shape of the waveform of the first displacement information DS1 in step S104 (second acquisition process), and extracts intersection information DS1c from the first displacement information DS1 based on the estimated position. Therefore, it is not necessary to determine the position of the intersection CR between the first street region SR1 and the second street region SR2 based on, for example, the pattern of the surface 1a of the object 1.

[0100] Furthermore, in the laser processing apparatus 200 according to this embodiment, the control unit 500 can estimate, in step S104 (second acquisition process), the protrusions P of the concave-convex shape of the waveform of the first displacement information DS1 as the positions of the intersections CR between the first street region SR1 and the second street region SR2. Therefore, the intersection information DS1c can be extracted more reliably from the first displacement information DS1 based on the concave-convex shape of the waveform of the first displacement information DS1.

[0101] Here, after laser processing of all first street regions SR1 (i.e., all lines to cut 5a) is completed, laser processing of second street regions SR2 can be performed as shown in Figures 20 and 21. In this case, the control unit 500 first controls the first moving mechanism 220 to rotate the support table 230, thereby establishing a second processing state in which the second street regions SR2 (i.e., lines to cut 5b) determined in step S102 are parallel to the X-axis direction.

[0102] Thereafter, the control unit 500 performs steps S103 to S106 on the second street region SR2. As a result, a modified region is formed in the object 1 along the line to cut 5b in the second street region SR2. Note that here, the width of the second street region SR in the extension direction of the second street region SR2 is also narrower than the spot diameter of the first measurement laser beam L1 on the surface 1a.

[0103] In this way, the control unit 500 can perform a third acquisition process (step S103) in which the separate axis ranging sensor 450 acquires first displacement information DS1 in the second street area SR2 by scanning the first measurement laser light L1 over the second street area SR2.

[0104] In addition, the control unit 500 can perform a fourth acquisition process (steps S104, S105) in which it extracts multiple pieces of intersection information DS1c corresponding to the intersection CR between the second street area SR2 and the first street area SR1 from the first displacement information DS1 acquired in the third acquisition process, and interpolates the extracted multiple pieces of intersection information DS1c in the X-axis direction (the second direction in the second processing state) to acquire third displacement information DS3 (see (c) of Figure 21) corresponding to the displacement of the second street area SR2.

[0105] Furthermore, the control unit 500 can perform a second processing process (step S106) to form a modified area on the object 1 by scanning the laser light L over the second street area SR2 while adjusting the position of the focal point of the laser light L in the Z-axis direction that intersects with the surface 1a, which is the incident surface of the laser light L of the object 1, based on the third displacement information DS3.

[0106] In this case, when scanning the second street region SR2 with the laser light L, the first measurement laser light L1 is scanned over the second street region SR2 in the same manner as in the first street region SR1, thereby acquiring first displacement information DS1 corresponding to the displacement of the second street region SR2. Then, intersection information DS1c is extracted from the first displacement information DS1, and the extracted intersection information DS1c is interpolated in the X-axis direction to acquire third displacement information DS3 that more accurately reflects the actual displacement of the second street region SR2. Therefore, even when scanning the second street region SR2 with the laser light L, it is possible to more reliably suppress a decrease in the tracking accuracy of the focal point of the laser light L in the Z-axis direction that intersects with the surface 1a, which is the incident surface of the laser light L of the object 1.

[0107] The above embodiment has described one aspect of the laser processing apparatus and laser processing method according to the present invention. Therefore, the laser processing apparatus and laser processing method according to the present invention are not limited to the above embodiment and can be modified as desired. Next, modified examples will be described.

[0108] In the above embodiment, the case has been exemplified where the width of the first street region SR1 (and the second street region SR2) is narrower than the size of the spot of the first measurement laser beam L1 on the surface 1a of the object 1. However, as shown in FIG. 22 , the size of the spot of the first measurement laser beam L1 on the surface 1a of the object 1 may be smaller than the width of the first street region SR1 (and the second street region SR2).

[0109] 22, two parallel lines to cut 5a are set in one first street region SR1 (i.e., two-line processing is performed). Each of the lines to cut 5a is offset to one side or the other in the Y-axis direction from the center of the first street region SR1 in the Y-axis direction. In step S106, the first street region SR1 is scanned with laser light L along these lines to cut 5a.

[0110] Therefore, the position at which the separate-axis distance measuring sensor 450 acquires the first displacement information DS1 is also on one side or the other side of the center of the first street region SR1 in the Y-axis direction. In other words, in step S103, the spot of the first measurement laser beam L1 is aligned on one side or the other side of the center of the first street region SR1 in the Y-axis direction. Therefore, as described above, even if the size of the spot of the first measurement laser beam L1 on the surface 1a of the object 1 is smaller than the width of the first street region SR1, there is a risk that part of the first measurement laser beam L1 will be irradiated onto the device region DR.

[0111] Therefore, in this case as well, as in the above embodiment, multiple pieces of intersection information DS1c corresponding to the intersection Cr between the first street area SR1 and the second street area SR2 are extracted from the first displacement information DS1 obtained in step S103, and the extracted multiple pieces of intersection information DS1c are interpolated in the X-axis direction to obtain second displacement information DS2, and tracking processing can be performed using the second displacement information DS2.

[0112] As described above, in the laser processing apparatus 200, the control unit 500 can scan the first measurement laser beam L1 and the laser beam L on one side (or the other side) of the center of the first street region SR1 in the Y-axis direction in the first acquisition process (step S103) and the first processing process (step S106). In this case, since the influence of noise in the first displacement information DS1 may be large in areas in the first street region SR1 other than the intersections CR with the second street region SR2, it is more advantageous to use the second displacement information DS2 obtained by interpolating intersection information DS1c, which has relatively little noise, from the first displacement information DS1.

[0113] 23, there are cases where a plurality of structures T (e.g., metal pads or resin films) with different reflectivities are formed in the first street region SR1 (or the second street region SR2). In this case, the amount of reflected light of the first measurement laser beam L1 varies depending on the reflectivity of each structure T, which may make it difficult to acquire first displacement information DS1 that accurately reflects the displacement of the first street region SR1.

[0114] Therefore, in this case, the control unit 500 may extract displacement information at positions corresponding to specific structures T with the same reflectance from the first displacement information DS1 acquired by scanning the first street region SR1 with the first measurement laser light L1, and may interpolate the extracted displacement information in the X-axis direction to acquire second displacement information DS2 that more accurately reflects the actual displacement of the first street region SR1. In this case, the structure T located at the intersection of the first street region SR1 and the second street region SR2 may be selected as the structure T from which displacement information is extracted.

[0115] In this case, the width of the first street region SR1 (or the second street region SR2) may be narrower or wider than the spot size of the first measurement laser beam L1. However, when the width of the first street region SR1 (or the second street region SR2) is narrower than the spot size of the first measurement laser beam L1, it is effective to extract displacement information (i.e., intersection information DS1c) for the structure T formed at the intersection CR of the first street region SR1 and the second street region SR2, as described above.

[0116] Furthermore, in the above embodiment, the separate-axis distance measuring sensor 450 is used as the displacement information acquiring unit for acquiring the first displacement information DS1. However, in the laser processing apparatus 200, the coaxial distance measuring sensor 460 may be used as the displacement information acquiring unit for acquiring the first displacement information DS1. In this case, the optical axis of the second measurement laser beam L2 from the coaxial distance measuring sensor 460 and the optical axis of the processing laser beam L are coaxial. Therefore, it becomes difficult to perform step S103 and step S106 in a partially overlapping manner, as in the above embodiment, by sequentially acquiring the first displacement information DS1 (i.e., the second displacement information DS2) with the second measurement laser beam L2 leading the way while performing processing with the trailing laser beam L.

[0117] Therefore, in this case, the control unit 500 first performs steps S103 to S105 on at least one first street region SR1 to complete acquisition of first displacement information DS1 and second displacement information DS2 corresponding to the displacement of the first street region SR1. Thereafter, the control unit 500 performs step S106 on the first street region SR1 for which second displacement information DS2 has been acquired, thereby performing follow-up processing. This makes it possible to achieve the same effect as when the separate-axis distance measuring sensor 450 is used.

[0118] When using the coaxial distance measuring sensor 460, the size of the spot on the surface 1a of the second measurement laser light L2 is, for example, the spot diameter on the surface 1a of the second measurement laser light L2 at the Z-axis position of the focusing lens unit 430 (i.e., the reticle focus position) when the mark on the reticle 483 is in focus on the image of the laser light incident surface captured by the observation camera 488.

[0119] Furthermore, in the above embodiment, the control unit 500 estimates the position of the intersection CR based on the concave and convex shape of the waveform of the first displacement information DS1 in steps S104 and S105, and extracts the intersection 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 determine the position of the intersection CR based on the pattern of the surface 1a of the target object 1 registered in step S101.

[0120] That is, in the second acquisition process (steps S104 and S105), the control unit 500 may determine the position of the intersection CR between the first street area SR1 and the second street area SR2 based on pattern information including the patterns of the first street area SR1 and the second street area SR2 on the surface 1a, and extract the intersection information DS1c from the first displacement information DS1 based on the determined position. In this case, when extracting the intersection information DS1c from the first displacement information DS1, it is not necessary to estimate the position of the intersection CR between the first street area SR1 and the second street area SR2. Therefore, the intersection information DS1c can be extracted more reliably and in a shorter time. [Explanation of symbols]

[0121] 1...object, 1a...surface (incident surface), 200...laser processing device, 220...first moving mechanism (moving mechanism), 230...support table (supporting section), 400...laser focusing section (irradiation section), 440...driving mechanism (moving mechanism), 450...separate axis ranging sensor (displacement information acquiring section), 460...coaxial ranging sensor (displacement information acquiring section), 500...control section, L...laser light, L1...first measurement laser light (measurement laser light), L2...second measurement laser light (measurement laser light), SR1...first street area, SR2...second street area, CR...intersection, DS1...first displacement information, DS1c...intersection information, DS2...second displacement information, P...protrusion.

Claims

1. A laser processing device for irradiating a target with laser light to form a modified region, a support portion for supporting the object; an irradiation unit for irradiating the laser light onto the object supported by the support unit; a displacement information acquiring unit that irradiates a measurement laser beam onto an incident surface of the laser beam of the object supported by the support unit and receives reflected light of the measurement laser beam from the incident surface, thereby acquiring 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 measurement laser light relative to the object; a control unit for controlling the moving mechanism to scan the laser light and the measurement laser light over the object; Equipped with When viewed from a direction intersecting the incident plane, the incident plane of the object is: a plurality of device regions arranged along a first direction and a second direction that intersect with each other; a plurality of first street regions extending along the first direction, the first street regions being regions between the device regions adjacent to each other along the second direction; a plurality of second street regions extending along the second direction, the second street regions being regions between the device regions adjacent to each other along the first direction; Including, The control unit a first acquisition process for causing the displacement information acquisition unit to acquire the first displacement information in the first street area by scanning the measurement laser light over the first street area; a second acquisition process for extracting, from the first displacement information acquired in the first acquisition process, a plurality of pieces of intersection information corresponding to intersections between the first street area and the second street area, and interpolating the extracted plurality of pieces of intersection information in the first direction to acquire second displacement information corresponding to the displacement of the first street area; a first processing process of forming the modified region in the object by scanning the laser light over the first street region while adjusting the position of the light focusing point in a direction intersecting the incident plane based on the second displacement information; To carry out Laser processing equipment.

2. a width of the first street region in the second direction is narrower than a size of a spot of the measurement laser light on the incident surface; The laser processing device according to claim 1 .

3. the control unit, in the first acquisition process and the first processing process, scans the measurement laser light and the laser light on one side in the second direction of a center of the first street region in the second direction. The laser processing device according to claim 1 .

4. In the second acquisition process, the control unit estimates a position of an intersection between the first street area and the second street area based on a concave-convex shape of a waveform of the first displacement information, and extracts the intersection information from the first displacement information based on the estimated position. The laser processing device according to claim 1 .

5. the control unit, in the second acquisition process, estimates a protruding portion of an uneven shape of the waveform of the first displacement information as a position of an intersection of the first street area with the second street area. The laser processing device according to claim 4.

6. the control unit, in the second acquisition process, determines a position of an intersection between the first street area and the second street area based on pattern information including patterns of the first street area and the second street area on the incident surface, and extracts the intersection information from the first displacement information based on the determined position. The laser processing device according to claim 1 .

7. The control unit a third acquisition process of causing the displacement information acquisition unit to acquire the first displacement information in the second street area by scanning the measurement laser light over the second street area; a fourth acquisition process for extracting, from the first displacement information acquired in the third acquisition process, a plurality of pieces of intersection information corresponding to intersections between the second street area and the first street area, and interpolating the extracted plurality of pieces of intersection information in the second direction to acquire third displacement information corresponding to the displacement of the second street area; a second processing process of forming the modified region in the object by scanning the laser light over the second street region while adjusting the position of the light focusing point in a direction intersecting the incident plane based on the third displacement information; To carry out The laser processing device according to any one of claims 1 to 6.

8. A laser processing method for forming a modified region by irradiating a target with laser light, comprising: a first acquisition step of irradiating a measurement laser beam onto an incident surface of the laser beam of the object and receiving reflected light of the measurement laser beam from the incident surface, thereby acquiring first displacement information corresponding to a displacement of the incident surface; a second acquisition step of acquiring second displacement information based on the first displacement information; a processing step of forming the modified region in the object by scanning the laser light over the object; Equipped with When viewed from a direction intersecting the incident plane, the incident plane of the object is: a plurality of device regions arranged along a first direction and a second direction that intersect with each other; a plurality of first street regions extending along the first direction, the first street regions being regions between the device regions adjacent to each other along the second direction; a plurality of second street regions extending along the second direction, the second street regions being regions between the device regions adjacent to each other along the first direction; Including, in the first acquisition step, the first displacement information in the first street area is acquired by scanning the measurement laser light over the first street area; In the second acquisition step, a plurality of pieces of intersection information corresponding to intersections between the first street area and the second street area are extracted from the first displacement information acquired in the first acquisition step, and second displacement information corresponding to the displacement of the first street area is acquired by interpolating the extracted plurality of pieces of intersection information in the first direction; In the processing step, the modified region is formed in the object by scanning the laser light over the first street region while adjusting the position of a focal point of the laser light in a direction intersecting the incident surface based on the second displacement information. Laser processing method.

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