Laser processing device and laser processing method

Abstract

To improve a processing quality by adjusting an output of a branched beam into a desired value.SOLUTION: A laser processing device 1 is configured to execute: first processing for generating a first branching pattern on the basis of a predetermined calculation formula and making a reflection-type spatial beam modulator 34 display the generated first branching pattern; second processing for controlling a beam source unit 8 so that a laser beam is emitted; third processing for controlling a detecting part 17 so that a reflected beam of each laser beam branched by the first branching pattern is detected; fourth processing for deriving an actual output measured value of each branched laser beam and creating a balance parameter relating to a creation of a second branching pattern which is a branching pattern in which the actual output measured value is made to approach an output target value; and fifth processing for correcting a calculation formula by the balance parameter, creating the second branching pattern on the basis of the corrected calculation formula, setting the pattern on the reflection-type spatial beam modulator 34 as the pattern for processing, and making the modulator display the pattern.SELECTED DRAWING: Figure 1

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 that includes a laser light source, a spatial light modulator, and a focusing correction means different from the spatial light modulator. This laser processing device divides and peels off an object (wafer) by forming a modified region inside the object by irradiating it with laser light. The technology described in Patent Document 1 forms a modified region inside the object by irradiating it with laser light, captures an image of a portion of the light reflected from the focusing point, detects the amount of positional deviation of the focusing point based on the image capture result, and adjusts the modulation pattern in the spatial light modulator to reduce the positional deviation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6620976 Summary of the Invention [Problem to be solved by the invention]

[0004] In the laser processing apparatus described above, a branching pattern may be set in the spatial light modulator so that multiple modified regions are formed simultaneously, and the laser beam may be branched according to the branching pattern. The branching pattern may be set, for example, according to the target output value of each branched laser beam. Here, when branching laser beams using a spatial light modulator, for example, the output of each branched laser beam may not reach the target output value (design value) described above due to the influence of the optical characteristics of the spatial light modulator itself, the optical characteristics of the lenses where the transmission regions of each branched beam differ from each other, or individual differences in optical elements. It is difficult to completely avoid this phenomenon. If the output of each branched laser beam does not reach the expected value, the crack extending from the modified region may not be the desired crack size, resulting in the object not being divided or peeled (deteriorating processing quality).

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a laser processing apparatus and a laser processing method that can improve processing quality by adjusting the output of branched light to a desired value. [Means for solving the problem]

[0006] A laser processing apparatus according to one aspect of the present invention is a laser processing apparatus for forming a modified region in an object by irradiating the object with laser light, the laser processing apparatus comprising: a light source for emitting laser light; a spatial light modulator for modulating the laser light emitted from the light source; a detection unit for detecting reflected light of the laser light from the object; and a control unit, wherein the control unit performs a first process of generating a branch pattern for branching the laser light into a plurality of beams based on a predetermined calculation algorithm, the first branch pattern being in accordance with an output target value of each of the branched laser beams, setting the generated first branch pattern on the spatial light modulator and displaying it; and controlling the light source so that the laser light is emitted in a state in which the first branch pattern is displayed on the spatial light modulator. a third process of controlling the detection unit so that reflected light of each laser beam after branching by the first branching pattern is detected; a fourth process of deriving an actual output value of each laser beam after branching based on the detection results by the detection unit and generating correction parameters for correcting the calculation algorithm, which are correction parameters related to generating a second branching pattern, which is a branching pattern that brings the actual output value closer to the output target value; and a fifth process of correcting the calculation algorithm using the correction parameters, generating a second branching pattern based on the corrected calculation algorithm, and setting and displaying the generated second branching pattern on a spatial light modulator for the processing process.

[0007] In a laser processing apparatus according to one aspect of the present invention, a laser beam is emitted while a first branching pattern generated according to the output target value of each branched laser beam is displayed on a spatial light modulator. Reflected light from an object is detected, and actual measured output values ​​of each laser beam are derived based on the detection results. Then, in this laser processing apparatus, correction parameters for generating a second branching pattern that brings the actual measured output values ​​closer to the output target values ​​are generated. A calculation algorithm corrected using the correction parameters generates the second branching pattern, and the second branching pattern is displayed on the spatial light modulator for the processing process. With this configuration, correction parameters are generated for generating a second branching pattern that brings the actual measured output value, estimated with high accuracy based on the actually detected reflected light, closer to the output target value. During the processing process, the calculation algorithm is corrected using the correction parameters to generate a second branching pattern that brings the output of the branched beam closer to the output target value than the first branching parameter, thereby appropriately adjusting the output of the branched beam to a desired value. As described above, the laser processing apparatus according to one aspect of the present invention can adjust the output of the branched beam to a desired value and improve processing quality.

[0008] The control unit may generate, in the first process, a plurality of types of first branching patterns each having a different combination of output target values ​​for each branched laser beam, and may generate, in the fourth process, a common correction parameter for at least two of the plurality of types of first branching patterns. In this way, by generating a common correction parameter for a plurality of first branching patterns each having a different output target value condition, it becomes possible to generate unique second branching patterns using the same correction parameter, and it is possible to simplify the process of generating and managing the correction parameter compared to when a correction parameter is generated for each first branching pattern.

[0009] In the fourth process, the control unit may group the multiple types of first branching patterns according to the degree of similarity of their branching parameters and generate a common correction parameter for each group. For example, if one common correction parameter is generated for all first branching patterns, and first branching patterns whose branching parameters are significantly different from one another are included, correcting the calculation algorithm using the generated common correction parameter may not sufficiently improve the accuracy of all second branching patterns (the accuracy of bringing the output of branched light closer to the output target value). In this regard, by generating a common correction parameter for each group whose branching parameters are similar, i.e., by generating different correction parameters for groups whose branching parameters are not similar, the accuracy of the second branching patterns (the accuracy of bringing the output of branched light closer to the output target value) can be ensured.

[0010] In the fourth process, the control unit may perform grouping according to the degree of approximation of the output target value, which is the branching parameter. This allows a common correction parameter to be generated for each group whose output target value is similar, thereby ensuring the accuracy of the second branching pattern (the accuracy of bringing the output of branched light closer to the output target value).

[0011] In the fifth process, the control unit may acquire information indicating branch parameters in the machining process and correct the calculation algorithm using correction parameters of the group corresponding to the branch parameters. This allows the machining process to be performed while displaying the second branch pattern generated by the calculation algorithm corrected using correction parameters suitable for the branch parameters in the machining process, thereby improving machining quality.

[0012] In the first process, the control unit may generate a first branching pattern that branches the laser beam to different positions in a vertical direction, which is the thickness direction of the object. During actual processing, the laser beam may be branched to different positions in the vertical direction (vertical branching), and by generating the first branching pattern related to the vertical branching, it is possible to generate correction parameters related to generation of a second branching pattern that can appropriately bring the output of the branched beam in the case of vertical branching closer to the output target value.

[0013] A laser processing method according to one embodiment of the present invention is a laser processing method for forming a modified region in an object by irradiating the object with laser light, and includes the following steps: a first step of generating a branch pattern that branches laser light into multiple beams based on a predetermined calculation algorithm, a first branch pattern corresponding to an output target value of each branched laser light, and setting and displaying the generated first branch pattern on a spatial light modulator; a second step of emitting laser light to the spatial light modulator on which the first branch pattern is displayed, and irradiating the object with the laser light branched into multiple beams by the first branch pattern; a third step of detecting reflected light of each branched laser light from the object; a fourth step of deriving an actual output measured value of each branched laser light based on the detection results of the reflected light, and generating correction parameters for correcting the calculation algorithm, the correction parameters being related to generating a second branch pattern, which is a branch pattern that brings the actual output value closer to the output target value; and a fifth step of correcting the calculation algorithm using the correction parameters, generating a second branch pattern based on the corrected calculation algorithm, and setting and displaying the generated second branch pattern on the spatial light modulator for the processing process.

[0014] A laser processing method according to another aspect of the present invention includes a first step of generating a first branching pattern that branches laser light into multiple beams based on a predetermined calculation algorithm, the first branching pattern corresponding to the output target value of each laser light after branching, and setting and displaying the generated first branching pattern on a spatial light modulator; a second step of emitting laser light to the spatial light modulator on which the first branching pattern is displayed, and measuring the laser light branched into multiple beams by the first branching pattern with a power meter to derive actual measured output values ​​of each laser light after branching; and a third step of generating and outputting correction parameters for correcting the calculation algorithm, the correction parameters being related to the generation of a second branching pattern that is a branching pattern that brings the actual measured output value closer to the output target value.

[0015] In a laser processing method according to another aspect of the present invention, a first branching pattern, set according to the output target value of each branched laser beam, is set in a spatial light modulator, and a laser beam is emitted. The laser beams branched by the first branching pattern are measured by a power meter, and actual output values ​​of each branched laser beam are derived based on the measurement results. In this laser processing method, correction parameters for generating a second branching pattern that brings the actual output value closer to the output target value are generated and output. With this configuration, correction parameters are generated for generating a second branching pattern that brings the actual output value measured by the power meter closer to the output target value. By generating the correction parameters so that the actually measured output approaches the target value, the calculation algorithm is corrected using the correction parameters during the processing process, and a second branching pattern is generated that brings the output of the branched beam closer to the output target value than the first branching parameter, thereby appropriately adjusting the output of the branched beam to a desired value. As described above, the laser processing method according to one aspect of the present invention can adjust the output of the branched beam to a desired value and improve processing quality.

[0016] In the laser processing method according to the above-described other aspect, the second step may include performing a light-shielding output measurement process in which the output of each of the split laser beams is measured with a power meter while a part of the split laser beams is shielded with a light shielding plate, and in the light-shielding output measurement process, the output of each of the split laser beams is measured with the power meter while changing the range of the laser beams shielded by the light shielding plate. In this way, the output of each of the split laser beams is measured with the power meter while changing the range of the laser beams shielded by the light shielding plate, so that the output of each of the split laser beams can be appropriately derived. [Effects of the Invention]

[0017] According to the present invention, the output of the branched light can be adjusted to a desired value, thereby improving the processing quality. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a perspective view of a laser processing apparatus according to an embodiment; [Figure 2] FIG. 2 is a front view of a portion of the laser processing apparatus shown in FIG. [Figure 3] 2 is a front view of a laser processing head of the laser processing apparatus shown in FIG. 1. [Figure 4] FIG. 4 is a side view of the laser processing head shown in FIG. 3. [Figure 5] FIG. 4 is a configuration diagram of an optical system of the laser processing head shown in FIG. 3. [Figure 6] FIG. 2 is a plan view illustrating a plurality of modified spots. [Figure 7] FIG. 10 is a diagram illustrating an example of a GUI setting screen. [Figure 8] FIG. 10 is a diagram illustrating an example of an administrator mode of a GUI setting screen. [Figure 9] 10 is a table showing the error of the actual measured value from the design value at each output ratio when branching at two points. [Figure 10] 10 is a table showing the error of the actual measured value from the design value at each output ratio when branching at three points. [Figure 11] 10 is a table showing the error of the actual measured value from the design value at each output ratio when branching at four points. [Figure 12] FIG. 10 is a diagram illustrating a vertical branching mode. [Figure 13] 10 is a table showing the error of the actual measured value from the design value at each output ratio when the balance parameters obtained without vertical branching are applied to machining with vertical branching (VD16). [Figure 14] 10 is a table showing the error of the actual measured value from the design value at each output ratio when the balance parameters acquired with vertical branching (VD16) are applied to machining with vertical branching (VD16). [Figure 15] 10 is a table showing the relationship between the amount of vertical branching and the maximum error. [Figure 16] 10 is a table showing the error of the actual measurement value from the design value at each output ratio when a balance parameter is applied to each region. [Figure 17] FIG. 10 is a diagram illustrating the operation of balance parameters according to branch parameters. [Figure 18] FIG. 10 is a diagram illustrating the operation of balance parameters according to branch parameters. [Figure 19] 10 is a flowchart illustrating a process of generating a branch pattern to which a balance parameter is applied. [Figure 20] 10 is a flowchart illustrating a process of generating a branch pattern to which a balance parameter is applied. [Figure 21] FIG. 10 is a schematic configuration diagram of a laser processing device according to a modified example. [Figure 22] 10A and 10B are diagrams illustrating the output derivation of each laser beam after branching using a power meter. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and duplicated explanations will be omitted.

[0020] First, the basic configuration of the laser processing device will be described.

[0021] [Basic configuration of laser processing equipment] As shown in FIG. 1, the laser processing apparatus 1 includes multiple movement mechanisms 5 and 6, a support unit 7, a pair of laser processing heads 10A and 10B, a light source unit 8, and a control unit 9. While the following describes an example in which there is a pair of laser processing heads, there may be only one laser processing head. Hereinafter, the first direction will be referred to as the X direction, the second direction perpendicular to the first direction as the Y direction, and the third direction perpendicular to the first and second directions as the Z direction. In this embodiment, the X and Y directions are horizontal directions, and the Z direction is vertical.

[0022] The movement mechanism 5 has a fixed part 51, a moving part 53, and an attachment part 55. The fixed part 51 is attached to the device frame 1a. The moving part 53 is attached to a rail provided on the fixed part 51 and can move along the Y direction. The attachment part 55 is attached to a rail provided on the moving part 53 and can move along the X direction.

[0023] The movement mechanism 6 has a fixed part 61, a pair of moving parts 63 and 64, and a pair of mounting parts 65 and 66. The fixed part 61 is attached to the device frame 1a. Each of the pair of moving parts 63 and 64 is attached to a rail provided on the fixed part 61, and each can move independently along the Y direction. The mounting part 65 is attached to a rail provided on the moving part 63, and can move along the Z direction. The mounting part 66 is attached to a rail provided on the moving part 64, and can move along the Z direction. In other words, each of the pair of mounting parts 65 and 66 can move along the Y direction and the Z direction relative to the device frame 1a.

[0024] The support unit 7 is attached to a rotation shaft provided on the mounting unit 55 of the movement mechanism 5, and can rotate around an axis parallel to the Z direction as a center line. In other words, the support unit 7 can move along both the X direction and the Y direction, and can rotate around an axis parallel to the Z direction as a center line. The support unit 7 supports the object 100. The object 100 is, for example, a wafer.

[0025] 1 and 2, the laser processing head 10A is attached to the mounting portion 65 of the moving mechanism 6. The laser processing head 10A faces the support portion 7 in the Z direction and irradiates the object 100 supported by the support portion 7 with laser light L1. The laser processing head 10B is attached to the mounting portion 66 of the moving mechanism 6. The laser processing head 10B faces the support portion 7 in the Z direction and irradiates the object 100 supported by the support portion 7 with laser light L2.

[0026] The light source unit 8 has a pair of light sources 81, 82. The light source 81 outputs laser light L1. The laser light L1 is emitted from an emission portion 81a of the light source 81 and guided to the laser processing head 10A by an optical fiber 2. The light source 82 outputs laser light L2. The laser light L2 is emitted from an emission portion 82a of the light source 82 and guided to the laser processing head 10B by another optical fiber 2.

[0027] The control unit 9 controls each part of the laser processing device 1 (such as the support unit 7, the multiple movement mechanisms 5 and 6, the pair of laser processing heads 10A and 10B, and the light source unit 8). The control unit 9 is configured as a computer device including a processor, memory, storage, and communication devices. In the control unit 9, software (programs) loaded into the memory, etc., are executed by the processor, and the processor controls the reading and writing of data in the memory and storage, as well as communication by the communication devices. In this way, the control unit 9 realizes various functions.

[0028] An example of processing using the laser processing apparatus 1 configured as above will be described. This example of processing is to form modified regions inside the object 100, which is a wafer, along multiple lines set in a grid pattern in order to cut the object 100 into multiple chips. Note that the laser processing apparatus 1 may also perform peeling processing, which peels off a portion of the object 100.

[0029] First, the movement mechanism 5 moves the support part 7 along each of the X and Y directions so that the support part 7 supporting the target object 100 faces the pair of laser processing heads 10A, 10B in the Z direction. Next, the movement mechanism 5 rotates the support part 7 about an axis parallel to the Z direction as the center line so that multiple lines extending in one direction on the target object 100 are aligned along the X direction.

[0030] Next, the movement mechanism 6 moves the laser processing head 10A along the Y direction so that the focal point (part of the focal area) of the laser light L1 is located on one line extending in one direction. Meanwhile, the movement mechanism 6 moves the laser processing head 10B along the Y direction so that the focal point of the laser light L2 is located on another line extending in one direction. Next, the movement mechanism 6 moves the laser processing head 10A along the Z direction so that the focal point of the laser light L1 is located inside the object 100. Meanwhile, the movement mechanism 6 moves the laser processing head 10B along the Z direction so that the focal point of the laser light L2 is located inside the object 100.

[0031] Next, the light source 81 outputs laser light L1 and the laser processing head 10A irradiates the object 100 with the laser light L1, and at the same time, the light source 82 outputs laser light L2 and the laser processing head 10B irradiates the object 100 with the laser light L2. At the same time, the movement mechanism 5 moves the support part 7 along the X direction so that the focal point of the laser light L1 moves relatively along one line extending in one direction and the focal point of the laser light L2 moves relatively along another line extending in the same direction. In this way, the laser processing apparatus 1 forms modified regions inside the object 100 along each of a plurality of lines extending in one direction on the object 100.

[0032] Next, the movement mechanism 5 rotates the support part 7 about an axis parallel to the Z direction as the center line so that a plurality of lines extending in another direction perpendicular to the one direction on the target object 100 are aligned along the X direction.

[0033] Next, the movement mechanism 6 moves the laser processing head 10A along the Y direction so that the focal point of the laser light L1 is located on one line extending in the other direction. Meanwhile, the movement mechanism 6 moves the laser processing head 10B along the Y direction so that the focal point of the laser light L2 is located on another line extending in the other direction. Next, the movement mechanism 6 moves the laser processing head 10A along the Z direction so that the focal point of the laser light L1 is located inside the object 100. Meanwhile, the movement mechanism 6 moves the laser processing head 10B along the Z direction so that the focal point of the laser light L2 is located inside the object 100.

[0034] Next, the light source 81 outputs laser light L1 and the laser processing head 10A irradiates the object 100 with the laser light L1, and at the same time, the light source 82 outputs laser light L2 and the laser processing head 10B irradiates the object 100 with the laser light L2. At the same time, the movement mechanism 5 moves the support part 7 along the X direction so that the focal point of the laser light L1 moves relatively along one line extending in the other direction and the focal point of the laser light L2 moves relatively along another line extending in the other direction. In this way, the laser processing apparatus 1 forms modified regions inside the object 100 along each of a plurality of lines extending in the other direction perpendicular to the one direction in the object 100.

[0035] In the example of the processing described above, the light source 81 outputs laser light L1, which is transparent to the object 100, for example, by pulse oscillation, and the light source 82 outputs laser light L2, which is transparent to the object 100, for example, by pulse oscillation. When such laser light is focused inside the object 100, the laser light is particularly absorbed in the portion corresponding to the focal point of the laser light, forming a modified region inside the object 100. The modified region is a region whose density, refractive index, mechanical strength, and other physical properties differ from those of the surrounding unmodified region. Examples of modified regions include a melt-treated region, a crack region, a dielectric breakdown region, and a refractive index change region.

[0036] When laser light output by a pulse oscillation method is irradiated onto the object 100 and the focal point of the laser light is moved relatively along a line set on the object 100, multiple modified spots are formed lined up in a row along the line. One modified spot is formed by irradiating one pulse of laser light. A row of modified regions is a collection of multiple modified spots lined up in a row. Adjacent modified spots may be connected to each other or separated from each other depending on the relative moving speed of the focal point of the laser light with respect to the object 100 and the repetition frequency of the laser light. The shape of the set line is not limited to a lattice shape, but may be circular, linear, curved, or a combination of at least any of these.

[0037] [Laser processing head configuration] As shown in FIGS. 3 and 4, the laser processing head 10A includes a housing 11, an incident section 12, an adjustment section 13, and a focusing section .

[0038] The housing 11 has a first wall portion 21 and a second wall portion 22, a third wall portion 23 and a fourth wall portion 24, and a fifth wall portion 25 and a sixth wall portion 26. The first wall portion 21 and the second wall portion 22 face each other in the X direction. The third wall portion 23 and the fourth wall portion 24 face each other in the Y direction. The fifth wall portion 25 and the sixth wall portion 26 face each other in the Z direction.

[0039] In the laser processing head 10A, the first wall 21 is located on the opposite side from the fixed portion 61 of the moving mechanism 6, and the second wall 22 is located on the fixed portion 61 side. The third wall 23 is located on the mounting portion 65 side of the moving mechanism 6, and the fourth wall 24 is located on the laser processing head 10B side opposite the mounting portion 65 (see FIG. 2). The fifth wall 25 is located on the opposite side from the support portion 7, and the sixth wall 26 is located on the support portion 7 side.

[0040] The housing 11 is configured so that the housing 11 can be attached to the attachment portion 65 with the third wall portion 23 disposed on the attachment portion 65 side of the movement mechanism 6. Specifically, the attachment portion 65 has a base plate 65a and an attachment plate 65b. The base plate 65a is attached to a rail provided on the movement portion 63 (see FIG. 2). The attachment plate 65b is erected at the end of the base plate 65a on the laser processing head 10B side (see FIG. 2). The housing 11 is attached to the attachment portion 65 by screwing the bolts 28 into the attachment plate 65b via the pedestals 27 with the third wall portion 23 in contact with the attachment plate 65b. The pedestals 27 are provided on each of the first wall portion 21 and the second wall portion 22. The housing 11 is detachable from the attachment portion 65.

[0041] Incident portion 12 is attached to fifth wall portion 25. Incident portion 12 causes laser light L1 to enter housing 11. Incident portion 12 is biased toward second wall portion 22 (one of the walls) in the X direction, and toward fourth wall portion 24 in the Y direction.

[0042] The incident portion 12 is configured so that a connection end portion 2a of the optical fiber 2 can be connected thereto. The connection end portion 2a of the optical fiber 2 is provided with a collimator lens that collimates the laser light L1 emitted from the output end of the fiber, and is not provided with an isolator that suppresses return light. The isolator is provided midway along the fiber, closer to the light source 81 than the connection end portion 2a. This allows for a reduction in the size of the connection end portion 2a, and therefore the size of the incident portion 12. Note that an isolator may be provided at the connection end portion 2a of the optical fiber 2.

[0043] The adjustment unit 13 is disposed within the housing 11. The adjustment unit 13 adjusts the laser light L1 incident from the incident unit 12. Each component of the adjustment unit 13 is attached to an optical base 29 provided within the housing 11. The optical base 29 is attached to the housing 11 so as to divide the area within the housing 11 into an area on the third wall portion 23 side and an area on the fourth wall portion 24 side. The optical base 29 is integrated with the housing 11. Each component of the adjustment unit 13 is attached to the optical base 29 on the fourth wall portion 24 side. Details of each component of the adjustment unit 13 will be described later.

[0044] The light collecting unit 14 is disposed on the sixth wall portion 26. Specifically, the light collecting unit 14 is disposed on the sixth wall portion 26 in a state where it is inserted through a hole 26a formed in the sixth wall portion 26 (see FIG. 5). The light collecting unit 14 collects the laser light L1 adjusted by the adjustment unit 13 and emits the laser light L1 to the outside of the housing 11. The light collecting unit 14 is biased toward the second wall portion 22 side (one of the wall portions) in the X direction, and biased toward the fourth wall portion 24 side in the Y direction.

[0045] 5, the adjustment unit 13 has an attenuator 31, a beam expander 32, and a mirror 33. The incident unit 12, and the attenuator 31, beam expander 32, and mirror 33 of the adjustment unit 13 are arranged on a straight line (first straight line) A1 extending along the Z direction. The attenuator 31 and the beam expander 32 are arranged on the straight line A1 between the incident unit 12 and the mirror 33. The attenuator 31 adjusts the output of the laser light L1 incident from the incident unit 12. The beam expander 32 expands the diameter of the laser light L1 whose output has been adjusted by the attenuator 31. The mirror 33 reflects the laser light L1 whose diameter has been expanded by the beam expander 32.

[0046] The adjustment unit 13 further includes a reflective spatial light modulator 34 and an imaging optical system 35. The reflective spatial light modulator 34 and the imaging optical system 35 of the adjustment unit 13, and the condenser 14 are arranged on a straight line (second straight line) A2 extending along the Z direction. The reflective spatial light modulator 34 is, for example, a reflective liquid crystal (LCOS: Liquid Crystal on Silicon) spatial light modulator (SLM: Spatial Light Modulator). The reflective spatial light modulator 34 modulates the laser light L1 reflected by the mirror 33. The reflective spatial light modulator 34 modulates the laser light L1 according to a displayed modulation pattern. At least a branching pattern for branching the laser light L1 into multiple beams is set and displayed on the reflective spatial light modulator 34. As a result, the laser light L1 incident on the reflective spatial light modulator 34 is branched into multiple laser beams in the reflective spatial light modulator 34 (see FIG. 6 , which will be described in detail later). The imaging optical system 35 constitutes a double-telecentric optical system in which the reflecting surface 34a of the reflective spatial light modulator 34 and the entrance pupil plane 14a of the light-collecting unit 14 are in an imaging relationship. The imaging optical system 35 is made up of three or more lenses.

[0047] The straight lines A1 and A2 are located on a plane perpendicular to the Y direction. The straight line A1 is located on the second wall 22 side (one of the walls) with respect to the straight line A2. In the laser processing head 10A, the laser light L1 enters the housing 11 from the incident unit 12, travels along the straight line A1, is reflected sequentially by the mirror 33 and the reflective spatial light modulator 34, travels along the straight line A2, and is emitted from the focusing unit 14 to the outside of the housing 11. The arrangement order of the attenuator 31 and the beam expander 32 may be reversed. The attenuator 31 may be disposed between the mirror 33 and the reflective spatial light modulator 34. The adjustment unit 13 may also include other optical components (for example, a steering mirror disposed in front of the beam expander 32).

[0048] The laser processing head 10A further includes a dichroic mirror 15, a measuring unit 16, a detecting unit 17, a driving unit 18, and a circuit unit 19.

[0049] The dichroic mirror 15 is disposed on the straight line A2 between the imaging optical system 35 and the condenser 14. That is, the dichroic mirror 15 is disposed within the housing 11 between the adjustment unit 13 and the condenser 14. The dichroic mirror 15 is attached to the optical base 29 on the side of the fourth wall 24. The dichroic mirror 15 transmits the laser light L1. From the viewpoint of suppressing astigmatism, the dichroic mirror 15 is preferably, for example, a cube type or a type of two plates arranged to have a twisted relationship.

[0050] The measurement unit 16 is disposed within the housing 11 on the first wall 21 side (opposite the one wall side) of the adjustment unit 13. The measurement unit 16 is attached to the optical base 29 on the fourth wall 24 side. The measurement unit 16 outputs measurement light L10 for measuring the distance between the surface of the object 100 (for example, the surface on which the laser light L1 is incident) and the condenser 14, and detects the measurement light L10 reflected from the surface of the object 100 via the condenser 14. That is, the measurement light L10 output from the measurement unit 16 is irradiated onto the surface of the object 100 via the condenser 14, and the measurement light L10 reflected from the surface of the object 100 is detected by the measurement unit 16 via the condenser 14.

[0051] More specifically, the measurement light L10 output from the measurement unit 16 is reflected in turn by the beam splitter 20 and the dichroic mirror 15 attached to the optical base 29 on the fourth wall 24 side, and is emitted from the light collecting unit 14 to the outside of the housing 11. The measurement light L10 reflected on the surface of the object 100 enters the housing 11 from the light collecting unit 14, is reflected in turn by the dichroic mirror 15 and the beam splitter 20, enters the measurement unit 16, and is detected by the measurement unit 16.

[0052] The detection unit 17 is disposed within the housing 11 on the first wall 21 side (opposite the one wall side) of the adjustment unit 13. The detection unit 17 is attached to the optical base 29 on the fourth wall 24 side. The detection unit 17 outputs observation light L20 for observing the surface of the object 100 (e.g., the surface on which the laser light L1 is incident) and detects the observation light L20 reflected from the surface of the object 100 via the condenser 14. That is, the observation light L20 output from the detection unit 17 is irradiated onto the surface of the object 100 via the condenser 14, and the observation light L20 reflected from the surface of the object 100 is detected by the detection unit 17 via the condenser 14. The detection unit 17 is, for example, a camera that detects (captures) the reflected observation light L20.

[0053] More specifically, the observation light L20 output from the detection unit 17 passes through the beam splitter 20, is reflected by the dichroic mirror 15, and is emitted from the condenser 14 to the outside of the housing 11. The observation light L20 reflected from the surface of the object 100 enters the housing 11 from the condenser 14, is reflected by the dichroic mirror 15, passes through the beam splitter 20, and is incident on the detection unit 17, where it is detected. The wavelengths of the laser light L1, the measurement light L10, and the observation light L20 are different from one another (at least their respective center wavelengths are shifted from one another).

[0054] Furthermore, the detection unit 17 detects a portion of the laser light L1 reflected by the surface of the object 100 (details will be described later). The portion of the laser light L1 reflected by the surface of the object 100 is a small amount of the laser light L1 reflected by the dichroic mirror 15 toward the detection unit 17, out of the laser light L1 reflected by the surface of the object 100.

[0055] The driving unit 18 is attached to the optical base 29 on the side of the fourth wall portion 24. The driving unit 18 moves the light collecting unit 14 arranged on the sixth wall portion 26 along the Z direction by, for example, the driving force of a piezoelectric element.

[0056] The circuit unit 19 is disposed within the housing 11 on the third wall 23 side relative to the optical base 29. That is, the circuit unit 19 is disposed within the housing 11 on the third wall 23 side relative to the adjustment unit 13, the measurement unit 16, and the detection unit 17. The circuit unit 19 is, for example, a plurality of circuit boards. The circuit unit 19 processes the signal output from the measurement unit 16 and the signal input to the reflective spatial light modulator 34. The circuit unit 19 controls the drive unit 18 based on the signal output from the measurement unit 16. As an example, the circuit unit 19 controls the drive unit 18 based on the signal output from the measurement unit 16 so that the distance between the surface of the object 100 and the focusing unit 14 is maintained constant (i.e., so that the distance between the surface of the object 100 and the focusing point of the laser light L1 is maintained constant). The housing 11 is provided with a connector (not shown) to which wiring is connected for electrically connecting the circuit unit 19 to the control unit 9 (see FIG. 1 ) and the like.

[0057] Like the laser processing head 10A, the laser processing head 10B includes a housing 11, an incident section 12, an adjustment section 13, a focusing section 14, a dichroic mirror 15, a measurement section 16, a detection section 17, a drive section 18, and a circuit section 19. However, as shown in Fig. 2, the components of the laser processing head 10B are arranged so as to have a plane-symmetric relationship with the components of the laser processing head 10A with respect to an imaginary plane that passes through the midpoint between the pair of mounting sections 65, 66 and is perpendicular to the Y direction.

[0058] For example, the housing (first housing) 11 of the laser processing head 10A is attached to the mounting portion 65 so that the fourth wall portion 24 is located on the laser processing head 10B side relative to the third wall portion 23 and the sixth wall portion 26 is located on the support portion 7 side relative to the fifth wall portion 25. In contrast, the housing (second housing) 11 of the laser processing head 10B is attached to the mounting portion 66 so that the fourth wall portion 24 is located on the laser processing head 10A side relative to the third wall portion 23 and the sixth wall portion 26 is located on the support portion 7 side relative to the fifth wall portion 25.

[0059] The housing 11 of the laser processing head 10B is configured so that the housing 11 is attached to the mounting portion 66 with the third wall portion 23 disposed on the mounting portion 66 side. Specifically, the mounting portion 66 has a base plate 66a and a mounting plate 66b. The base plate 66a is attached to a rail provided on the moving portion 63. The mounting plate 66b is erected at the end of the base plate 66a on the laser processing head 10A side. The housing 11 of the laser processing head 10B is attached to the mounting portion 66 with the third wall portion 23 in contact with the mounting plate 66b. The housing 11 of the laser processing head 10B is detachable from the mounting portion 66.

[0060] [Branching of laser light] 6 to 8, the branching of the laser beam for the purpose of cutting, peeling, etc. of the object 100 will be described below. As described above, the laser beam L1 is branched according to the branching pattern set and displayed on the reflective spatial light modulator 34.

[0061] Fig. 6 is a diagram illustrating multiple modified spots SA when the laser beam L1 is split into four. In the example shown in Fig. 6, the laser beam L1 is split so that multiple (four) modified spots SA are formed on the target object 100, aligned along an inclined direction C2 that is inclined with respect to an orthogonal direction perpendicular to the processing progression direction C1. The splitting of the laser beam L1 is achieved by a splitting pattern (modulation pattern) that is set and displayed on the reflective spatial light modulator 34 (see Fig. 5).

[0062] In the illustrated example, the laser beam L1 is branched into four, forming four modified spots SA. For adjacent pairs of the four branched modified spots SA, the spacing in the processing progress direction C1 is the branch pitch BPx, and the spacing in the direction perpendicular to the processing progress direction C1 is the branch pitch BPy. For a pair of modified spots SA formed by irradiating two consecutive pulses of laser beam L1, the spacing in the processing progress direction C1 is the pulse pitch PP. The angle between the processing progress direction C1 and the tilt direction C2 is the branch angle α.

[0063] 7 is a setting screen of the GUI 111 for realizing the branching of the laser beam L1 as shown in FIG. 6. The GUI 111 functions as an input unit for accepting input from a user. The setting screen of the GUI 111 shown in FIG. 7 includes a processing condition selection button 211 for selecting processing conditions, a branch number field 212 for inputting or selecting the number of branches of the laser beam L1, an index field 213 for inputting an index which is the distance traveled to the next processing line after laser processing along one processing line, an image 214 for inputting or displaying the number of branches and the index, a processing Z height field 215 for inputting the position of the modified spot SA in the Z direction, a processing speed field 216 for inputting the processing speed, and a condition switching method button 217 for selecting a processing condition switching method.

[0064] The processing condition selection button 211 allows the user to select specific processing conditions from multiple options. According to the index field 213, if the number of branches is 1, the laser processing head 10A is automatically moved in the index direction by the input value. If the number of branches is greater than 1, the laser processing head 10A is automatically moved in the index direction by an index based on the following formula: Index = (number of branches) x index input value

[0065] The image diagram 214 includes a display section 214a for displaying index input values, and an output input column 214b for inputting the output of each modified spot SA.

[0066] Fig. 8 is a diagram showing an example of the administrator mode of the setting screen of the GUI 111. The setting screen shown in Fig. 8 includes a branch direction selection button 221 for selecting the branch direction of the laser beam L1, a branch number field 222 for inputting or selecting the number of branches of the laser beam L1, a branch pitch input field 223 for inputting the branch pitch BPx, a branch pitch row number input field 224 for inputting the number of rows of the branch pitch BPx, a branch pitch input field 225 for inputting the branch pitch BPy, an index field 226 for inputting an index, an optical axis image 227 based on the number of branches, an outward / return path selection button 228 for selecting whether the scanning direction of the laser beam L1 is one direction (outward path) or the other direction (return path), and a balance adjustment start button 229 for automatically adjusting the balance of various numerical values.

[0067] [Branch pattern correction processing] In the laser processing apparatus 1 according to this embodiment, prior to performing a processing operation (process) for forming a modified region on the target object 100, a first branching pattern corresponding to the output ratio (output target value) of each branched laser beam is generated based on a predetermined calculation formula (calculation algorithm), laser beam is emitted to the target object 100 with the first branching pattern displayed on the reflective spatial light modulator 34, reflected light of each branched laser beam by the first branching pattern is detected, actual output values ​​of each branched laser beam are derived based on the detection results, and balance parameters (correction parameters) related to the generation of a second branching pattern that brings the actual output values ​​closer to the desired output ratio (output target value) are generated. Then, during processing, the calculation formula is corrected by the balance parameters in the laser processing apparatus 1, a second branching pattern is generated based on the corrected calculation formula, and the second branching pattern is set and displayed on the reflective spatial light modulator 34 for processing.

[0068] In this way, in the laser processing device 1 according to this embodiment, the first branching pattern generated based on a predetermined calculation formula is not used as is during processing, but rather, before processing, the actual measured output values ​​of each laser beam after branching when the first branching pattern is used are derived, and balance parameters related to generating a second branching pattern that reduces the error between the expected output ratio and the actual measured output value are generated, and during processing, the calculation formula is corrected using the balance parameters, and the second branching pattern generated from the corrected calculation formula is used. This makes it possible to appropriately adjust the output of the branched beam to a desired value (output ratio) and improve processing quality.

[0069] The above-mentioned error before correction (the error between the assumed output ratio and the actual measured output value) is caused by, for example, the optical characteristics of the spatial light modulator itself, the optical characteristics of the lens in which the transmission areas of the branched lights are different from each other, or the influence of individual differences in optical elements.

[0070] 9 is a table showing the error of the actual measured value from the design value (ideal output ratio) for each output ratio when branching at two points. The left diagram of FIG. 9 shows the error when the first branching pattern described above is used without performing correction using the balance parameter. As shown in the left diagram of FIG. 9, when correction using the balance parameter is not performed, the error is particularly large when the difference in output between the two branched points is large, for example, when the design value of the output ratio at branching at two points is 20:80, the actual measured value is 9:91 (error 11%), when the design value is 30:70, the actual measured value is 21:79 (error 9%), when the design value is 40:60, the actual measured value is 35:65 (error 5%), when the design value is 50:50, the actual measured value is 51:49 (error 1%), and when the design value is 60:40, the actual measured value is 65:35 (error 5%).

[0071] The laser processing apparatus 1 generates balance parameters that bring the actual output value closer to the design value (ideal output ratio) based on error information such as that shown in the left diagram of FIG. 9. The balance parameters correct the calculation formula for generating the branch pattern, enabling the generation of a second branch pattern (a branch pattern that brings the actual output value closer to the design value) using the corrected calculation formula. The right diagram of FIG. 9 shows the error when the second branch pattern generated after correction using the balance parameters is used. In the example shown in the right diagram of FIG. 9, the application of the balance parameters, i.e., the use of the second branch parameters generated by correcting the calculation formula using the balance parameters, reduces the error at each output ratio, with the maximum error being reduced to 3%. Note that FIG. 9 also shows the error when the first branch pattern is set to a condition without vertical branching and when the processing using the second branch pattern is also set to a condition without vertical branching.

[0072] The effect of generating and applying balance parameters is not limited to two-point branching, but is similar for other numbers of branches. FIG. 10 is a table showing the error of the actual measured value from the design value for each output ratio when there are three branching points. FIG. 11 is a table showing the error of the actual measured value from the design value for each output ratio when there are four branching points. As shown in the left diagram of FIG. 10, when no correction using the balance parameters is performed, the maximum error for each output ratio when there are three branching points is 8%. However, as shown in the right diagram of FIG. 10, by applying the balance parameters, the maximum error for each output ratio when there are three branching points is reduced to 3%. Furthermore, as shown in the left diagram of FIG. 11, when no correction using the balance parameters is performed, the maximum error for each output ratio when there are four branching points is 9%. However, as shown in the right diagram of FIG. 11, by applying the balance parameters, the maximum error for each output ratio when there are four branching points is reduced to 3%.

[0073] The laser processing apparatus 1 may generate a first branching pattern that performs vertical branching, in which the laser beam is branched to different positions in the Z direction (vertical direction), which is the thickness direction of the target object 100. FIG. 12 is a diagram illustrating the vertical branching. FIG. 12(a) shows each laser beam when branched into three points without vertical branching, and FIG. 12(b) shows each laser beam when branched into three points with vertical branching. In FIGS. 12(a) and 12(b), the horizontal axis represents the processing progress direction, and the vertical axis represents the Z direction (vertical direction). As shown in FIG. 12(a), in a state without vertical branching, each branched laser beam is irradiated at the same height in the Z direction. On the other hand, as shown in FIG. 12(b), in a state with vertical branching, each branched laser beam is irradiated at different heights in the Z direction. Note that "vertical branch VD0" in FIG. 12(a) means that there is no vertical branch, and "vertical branch VD16" in FIG. 12(b) means that there is vertical branch and the branch pitch in the Z direction is 16 μm.

[0074] FIG. 13 is a table showing the error of the actual measured value from the design value at each output ratio with three branching points when the balance parameters acquired without vertical branching are applied to machining with vertical branching (VD16). The left diagram of FIG. 13 shows the error when the first branching pattern without vertical branching is used. The right diagram of FIG. 13 shows the error when machining with vertical branching (VD16) is performed using the second branching parameters generated by correction using the balance parameters generated based on the error information for the case without vertical branching as shown in the left diagram of FIG. 13. As described above, when both the processing using the first branching pattern and the processing using the second branching pattern were performed without vertical branching, the maximum error was reduced to 3% with three branching points, as shown in the right diagram of FIG. 10. On the other hand, when balance parameters were generated using a first branch pattern without vertical branching, and correction using the balance parameters was performed to generate a second branch pattern, and machining with vertical branching (VD16) was performed using the second branch pattern, the maximum error was 4%, as shown in the right diagram of Fig. 13. In this way, if the conditions for balance parameter generation and vertical branching in machining are different from each other, it is thought that applying the balance parameters may not be able to sufficiently reduce the error of the actual measured value from the design value.

[0075] Figure 14 is a table showing the error of the actual measured value from the design value at each output ratio with three branching points when the balance parameters acquired with vertical branching (VD16) are applied to machining with vertical branching (VD16). By using vertical branching (VD16) for both the processing using the first branching pattern and the machining processing using the second branching pattern, the maximum error was reduced to 3%, as shown in the right diagram of Figure 14. In this way, by standardizing the conditions for balance parameter generation and vertical branching for machining, the error of the actual measured value from the design value can be sufficiently reduced.

[0076] FIG. 15 is a table showing the relationship between the vertical branching amount and the maximum error. The "vertical branching amount" in FIG. 15 refers to the vertical branching amount in the processing. The "maximum error" in FIG. 15 refers to the maximum error at a certain output ratio when balance parameters generated based on the first branching pattern of VD16 are applied and the vertical branching processing indicated by the "vertical branching amount" is performed. As shown in FIG. 16, when the balance parameters generated based on the first branching pattern of VD16 are applied and the branching processing of VD16 is performed, the maximum error is the smallest (0.8%). Also, as shown in FIG. 16, when the balance parameters generated based on the first branching pattern of VD16 are applied and the branching processing of VD2 is performed, the maximum error is relatively small at 1.4%. Thus, even if the vertical branching conditions for balance parameter generation and processing do not match, when processing with vertical branching is performed, the error can be reduced by using balance parameters generated under the conditions with vertical branching.

[0077] The laser processing apparatus 1 may generate a plurality of types of first branch patterns each having a different combination of output ratios (output target values) of the branched laser beams, and generate a common balance parameter for the plurality of types of first branch patterns. Here, for example, if a common balance parameter for each output ratio is generated so as to reduce (e.g., minimize) the error of the actual measurement value from the design value in region A (region surrounded by a solid-line rectangle) shown in the left diagram of FIG. 16, as shown in the left diagram of FIG. 16, the error in region A will be small, at 1% or less, but the errors in region B (region surrounded by a dash-dotted-line rectangle) and region C (region surrounded by a dashed-line rectangle), which are different from region A, will be large, at 3% to 6%. Thus, a balance parameter generated to reduce the error in a certain region cannot sufficiently reduce the error in regions distant from the region.

[0078] For this reason, the laser processing apparatus 1 may group the laser beams according to the degree of similarity of the output ratio (output target value), which is a branching parameter, and generate a common balance parameter for each group. That is, the laser processing apparatus 1 may generate a common balance parameter for each group (region) whose output ratios are similar. The right diagram of FIG. 16 shows the error in a three-point branch when a common balance parameter is generated for each of the regions A, B, and C. As shown in the right diagram of FIG. 16, when a common balance parameter is generated for each of the regions A, B, and C, the error between the design value and the actual measurement value can be reduced to about 1% for all output ratios. In this way, by switching the balance parameter depending on the output ratio used during processing, the error between the design value and the actual measurement value can be reduced.

[0079] The following describes in detail the functions of the control unit 9 that realize the branch pattern correction process described above.

[0080] The control unit 9 is configured to execute the following steps: a first process of generating a first branching pattern that branches laser light into multiple beams based on a predetermined calculation formula (calculation algorithm), the first branching pattern corresponding to the output ratio (output target value) of each laser beam after branching, and setting the generated first branching pattern on the reflective spatial light modulator 34 and displaying it; a second process of controlling the light source unit 8 so that laser light is emitted while the first branching pattern is displayed on the reflective spatial light modulator 34; a third process of controlling the detection unit 17 so that reflected light of each laser beam after branching by the first branching pattern is detected; a fourth process of deriving an actual output measurement value of each laser beam after branching based on the detection result by the detection unit 17, and generating a balance parameter (correction parameter) related to the generation of the second branching pattern, which is a branching pattern that is a correction parameter for correcting the calculation formula and brings the actual output measurement value closer to the desired output ratio (output target value); and a fifth process of correcting the calculation formula using the balance parameter, generating a second branching pattern based on the corrected calculation formula, and setting the generated second branching pattern on the reflective spatial light modulator 34 for the processing process and displaying it.

[0081] In the first process, the control unit 9 determines the output ratio based on information received on the setting screen of the GUI 111 (see FIGS. 7 and 8), and sets a first branching pattern corresponding to the determined output ratio in the reflective spatial light modulator 34. The control unit 9 generates the first branching pattern corresponding to the output ratio based on a calculation formula (calculation algorithm) stored in advance. The control unit 9 may generate multiple types of first branching patterns that have different combinations of output ratios of the laser beams after branching. The control unit 9 may also generate a first branching pattern that performs vertical branching, branching the laser beam to different positions in the Z direction (vertical direction), which is the thickness direction of the object 100.

[0082] In the second process, the control unit 9 controls the light source unit 8 so that, for example, the laser light is irradiated with an output (less than the modification threshold) that does not form a modified region on the object 100, while the first branching pattern is displayed on the reflective spatial light modulator 34. Note that the branched laser light may be irradiated onto an object (object for correction process) other than the object 100 to be laser processed after the branching pattern correction process.

[0083] In the third process, the control unit 9 controls the detection unit 17 so as to enable detection (imaging) of the reflected light of each branched laser light from the object 100 at least during the period in which each branched laser light is irradiated onto the object 100. The control unit 9 acquires from the detection unit 17 the image captured by the detection unit 17.

[0084] In the fourth process, the control unit 9 estimates (derives) the actual output value of each laser beam based on, for example, the luminance of each point corresponding to each branched laser beam in the imaging data acquired by the detection unit 17. The control unit 9 generates balance parameters for generating a second branching pattern that brings the actual output value closer to a desired output ratio as correction parameters for correcting the calculation formula. When multiple types of first branching patterns have been generated, the control unit 9 generates common correction parameters for at least two first branching patterns included in the multiple types of first branching patterns. The control unit 9 may generate common correction parameters for all first branching patterns, or may group the multiple types of first branching patterns according to the degree of similarity of the branching parameters and generate common balance parameters for each group. Examples of branching parameters include the number of branches, the output ratio (output target value), the amount of vertical branching, and the amount of individual aberration correction. In the example shown in FIG. 16, the control unit 9 groups the multiple types of first branching patterns according to the degree of similarity of the output ratio, which is the branching parameter, and generates balance parameters for each group of region A, region B, and region C.

[0085] In the fifth process, the control unit 9 executes a process of correcting the calculation formula with the balance parameter and generating a second branch pattern based on the corrected calculation formula, and a process of setting and displaying the second branch pattern on the reflective spatial light modulator 34 during the machining process. The control unit 9 may acquire information indicating the branch parameters in the machining process and correct the calculation formula using the balance parameters of the group corresponding to the branch parameters. FIGS. 17 and 18 are diagrams illustrating the operation of balance parameters according to branch parameters. For example, the control unit 9 may acquire information indicating the number of branches as information indicating the branch parameters in the machining process based on information received on the setting screen of the GUI 111 (see FIGS. 7 and 8). As shown in FIG. 17, the control unit 9 may specify a balance parameter according to the number of branches and correct the calculation formula using the specified balance parameter. FIG. 17 shows that when the number of branches is two, a two-point branch balance parameter is reflected in the calculation formula; when the number of branches is three, a three-point branch balance parameter is reflected in the calculation formula; and when the number of branches is four, a four-point branch balance parameter is reflected in the calculation formula.

[0086] The control unit 9 may acquire information indicating an output ratio as information indicating branch parameters in the machining process based on information received on a setting screen of the GUI 111 (see FIGS. 7 and 8), identify balance parameters corresponding to the output ratio, and correct the calculation formula using the identified balance parameters. For example, assume that balance parameters for three regions (region A, region B, and region C) corresponding to the output ratios are generated as shown in FIG. 16. In this case, as shown in FIG. 18, the control unit 9 reflects the balance parameters for region A (balance parameter list A shown in FIG. 18) in the calculation formula when the output ratio is to be included in region A, and reflects the balance parameters for region B (balance parameter list B shown in FIG. 18) in the calculation formula when the output ratio is to be included in region B.

[0087] Next, a process for generating a branch pattern to which a balance parameter is applied will be described with reference to Fig. 19 and Fig. 20. Fig. 19 and Fig. 20 are flowcharts for explaining a process for generating a branch pattern to which a balance parameter is applied. Fig. 19 shows an example in which one balance parameter is used, and Fig. 20 shows an example in which multiple balance parameters are used by switching between them.

[0088] As shown in FIG. 19, first, a first branch pattern is derived based on information (design values) received on the setting screen of GUI 111, and the first branch pattern is set and displayed on the reflective spatial light modulator 34 (step S1: first process).

[0089] Next, laser light L1 is emitted to the reflective spatial light modulator 34 on which the first branching pattern is displayed, and the laser light branched into multiple beams by the first branching pattern is irradiated onto the target object 100, thereby starting laser irradiation (step S2: second process).

[0090] Next, the reflected light of the branched light from the object 100 is detected (imaged) by the detection unit 17 (step S3: third step).

[0091] Next, based on the imaging data (detection results of reflected light), the actual output value of each laser light after branching is derived, and a balance parameter is generated from the error between the actual output value and the desired output ratio (output target value, design value) (step S4: fourth process).

[0092] Finally, the calculation formula is corrected using the balance parameters, a second branch pattern is generated based on the corrected calculation formula, and the generated second branch pattern is set and displayed on the reflective spatial light modulator 34 for the processing process (step S5: fifth step).

[0093] Next, an example of switching between multiple balance parameters will be described with reference to Fig. 20. As shown in Fig. 20, the processes of steps S11 to S14 are the same as the processes of steps S1 to S4 in Fig. 19. However, in step S14, multiple types of first branch patterns are grouped according to the degree of similarity of the branch parameters, and a balance parameter is generated for each group.

[0094] Then, information (machining conditions) indicating branching parameters in the machining process is acquired, and the balance parameters are switched based on the machining conditions (e.g., output ratio) (step S15). That is, balance parameters that match the machining conditions are selected from the plurality of balance parameters.

[0095] Finally, the calculation formula is corrected using the selected balance parameters, a second branch pattern is generated based on the corrected calculation formula, and the generated second branch pattern is set and displayed on the reflective spatial light modulator 34 for the processing process.

[0096] Next, the effects of the laser processing device 1 according to this embodiment will be described.

[0097] The laser processing apparatus 1 according to this embodiment is a laser processing apparatus that forms a modified region in the object 100 by irradiating the object 100 with laser light, and includes a light source unit 8 that emits laser light, a reflective spatial light modulator 34 that modulates the laser light emitted from the light source unit 8, a detection unit 17 that detects reflected light of the laser light from the object 100, and a control unit 9. The control unit 9 performs a first process of generating a branch pattern that branches the laser light into a plurality of beams based on a predetermined calculation formula, a first branch pattern that corresponds to an output target value of each branched laser beam, and setting and displaying the generated first branch pattern on the reflective spatial light modulator 34; and a second process of displaying the first branch pattern on the reflective spatial light modulator 34 when the first branch pattern is displayed on the reflective spatial light modulator 34. a third process of controlling the detection unit 17 so that reflected light of each laser beam after branching by the first branching pattern is detected; a fourth process of deriving an actual output measurement value of each laser beam after branching based on the detection result by the detection unit 17 and generating a balance parameter related to generation of a second branching pattern, which is a branching pattern that is a correction parameter for correcting a calculation formula and brings the actual output value closer to an output target value; and a fifth process of correcting the calculation formula using the balance parameter, generating a second branching pattern based on the corrected calculation formula, and setting and displaying the generated second branching pattern on the reflective spatial light modulator 34 for the processing process.

[0098] In the laser processing apparatus 1 according to this embodiment, a laser beam is emitted with a first branching pattern generated according to the output target value of each branched laser beam displayed on the reflective spatial light modulator 34. Reflected light from the target object 100 is detected, and the actual output value of each laser beam is calculated based on the detection results. Then, in the laser processing apparatus 1, balance parameters are generated for generating a second branching pattern that brings the actual output value closer to the output target value. The second branching pattern is generated using a formula corrected using the balance parameters, and the second branching pattern is displayed on the reflective spatial light modulator 34 for the processing process. This configuration generates balance parameters for generating a second branching pattern that brings the actual output value, estimated with high accuracy based on the actually detected reflected light, closer to the output target value. During the processing process, the formula is corrected using the balance parameters to generate a second branching pattern that brings the output of the branched beam closer to the output target value than the first branching parameter. This allows the output of the branched beam to be appropriately adjusted to a desired value. As described above, the laser processing apparatus 1 according to this embodiment can adjust the output of the branched beam to a desired value and improve processing quality.

[0099] The control unit 9 may generate, in the first process, a plurality of types of first branching patterns each having a different combination of output target values ​​for each branched laser beam, and may generate, in the fourth process, a common balance parameter for at least two of the plurality of types of first branching patterns. In this way, by generating a common balance parameter for a plurality of first branching patterns each having a different output target value condition, it becomes possible to generate unique second branching patterns using the same balance parameter, and the generation process and management of the balance parameter can be simplified compared to when a balance parameter is generated for each first branching pattern.

[0100] In the fourth process, the control unit 9 may group the multiple types of first branching patterns according to the similarity of their balance parameters and generate a common balance parameter for each group. For example, if one common balance parameter is generated for all first branching patterns, and first branching patterns whose branching parameters are significantly different from one another are included, correcting the calculation formula using the generated common balance parameter may not sufficiently improve the accuracy of all second branching patterns (the accuracy of bringing the output of branched light closer to the output target value). In this regard, by generating a common balance parameter for each group whose branching parameters are similar, i.e., by generating different balance parameters for groups whose branching parameters are not similar, the accuracy of the second branching patterns (the accuracy of bringing the output of branched light closer to the output target value) can be ensured.

[0101] In the fourth process, the control unit 9 may perform grouping according to the degree of approximation of the output target value, which is the branching parameter. This generates a common balance parameter for each group whose output target value is similar, thereby ensuring the accuracy of the second branching pattern (the accuracy of bringing the output of branched light closer to the output target value).

[0102] In the fifth process, the control unit 9 may acquire information indicating branch parameters in the machining process and correct the calculation formula using balance parameters of the group corresponding to the branch parameters. This allows the machining process to be performed while displaying the second branch pattern generated using the calculation formula corrected using balance parameters suitable for the branch parameters in the machining process, thereby improving the machining quality.

[0103] In the first process, the control unit 9 may generate a first branching pattern that branches the laser beam to different positions in the vertical direction, which is the thickness direction of the target object 100. During actual processing, the laser beam may be branched to different positions in the vertical direction (vertical branching), and by generating the first branching pattern related to the vertical branching, it is possible to generate a balance parameter related to generation of a second branching pattern that can appropriately bring the output of the branched beam in the case of vertical branching close to the output target value.

[0104] Although the embodiments have been described above, the present invention is not limited to the above embodiments. For example, as a method for measuring the output of each laser beam after branching for generating a balance parameter (correction parameter), a method for detecting reflected light from an object using a detection unit has been described, but the present invention is not limited to this. Specifically, the output of each laser beam after branching for generating a balance parameter may be measured by a power meter. Below, an embodiment using a power meter will be described with reference to FIGS. 21 and 22.

[0105] FIG. 21 is a schematic diagram of a laser processing apparatus 500 according to a modified example. As shown in FIG. 21, the laser processing apparatus 500 includes a laser light source 402, a reflective spatial light modulator 403, a 4f optical system 441, a light shielding plate 420, and a focusing optical system 404 in a housing 431. The laser processing apparatus 500 forms a modified region in an object by focusing laser light L on the object. Here, it is assumed that the balance parameter is generated during manufacturing or adjustment of the laser processing apparatus 500, and the object to be processed is not set on a stage (not shown). A power meter 700 for measuring the laser intensity is installed below the focusing optical system 404 (for example, placed on the stage (not shown)). The balance parameter is generated based on the laser light output measurement results obtained by the power meter 700 (details will be described later).

[0106] The laser light source 402 is fixed with screws or the like to a top plate 436 of the housing 431 so as to emit laser light L in the horizontal direction. The reflective spatial light modulator 403 modulates the laser light L emitted from the laser light source 402, and modulates the laser light L incident from the horizontal direction and reflects it obliquely upward relative to the horizontal direction.

[0107] The 4f optical system 441 adjusts the wavefront shape of the laser light L modulated by the reflective spatial light modulator 403, and has a first lens 441a and a second lens 441b. The first lens 441a and the second lens 441b are arranged on the optical path between the reflective spatial light modulator 403 and the condensing optical system 404 so that the distance of the optical path between the reflective spatial light modulator 403 and the first lens 441a is a first focal length of the first lens 441a, the distance of the optical path between the condensing optical system 404 and the second lens 441b is a second focal length of the second lens 441b, the distance of the optical path between the first lens 441a and the second lens 441b is the sum of the first focal length and the second focal length, and the first lens 441a and the second lens 441b form a double-telecentric optical system. According to this 4f optical system 441, it is possible to suppress the laser light L modulated by the reflective spatial light modulator 403 from changing its wavefront shape due to spatial propagation, and from increasing aberration.

[0108] The light-shielding plate 420 is an aperture member having an opening 420a that passes a first processing light and a second processing light, which will be described later. The light-shielding plate 420 is provided on a Fourier plane (i.e., a plane including the confocal point O) between the first lens 441a and the second lens 441b. As will be described later, the power meter 700 measures the output of the branched light while changing the range of the laser light L that is blocked by the light-shielding plate 420. Note that the position where the light-shielding plate 420 cuts off the laser light L does not necessarily have to be the position where the light-convergence point is most focused, as long as it is near the Fourier plane.

[0109] The focusing optical system 404 focuses the laser light L emitted by the laser light source 402 and modulated by the reflective spatial light modulator 403 onto the power meter 700. The focusing optical system 404 includes a plurality of lenses, and is installed on a bottom plate 433 of a housing 431 via a drive unit 432 including a piezoelectric element or the like.

[0110] In the laser processing apparatus 500 configured as described above, the laser light L emitted from the laser light source 402 travels horizontally within the housing 431, is reflected downward by the mirror 405a, and the light intensity is adjusted by the attenuator 407. Then, the laser light L is reflected horizontally by the mirror 405b, and the intensity distribution of the laser light L is homogenized by the beam homogenizer 460 before it enters the reflective spatial light modulator 403.

[0111] The laser light L incident on the reflective spatial light modulator 403 passes through a branching pattern, which is a modulation pattern displayed on the liquid crystal layer, and is modulated (branched) according to the modulation pattern. Such a modulation pattern (branching pattern) is generated by the control unit 450 according to the output target value of each branched laser light. Each branched laser light is then reflected upward by the mirror 406a, has its polarization direction changed by the λ / 2 wave plate 428, is reflected horizontally by the mirror 406b, and enters the 4f optical system 441.

[0112] The wavefront shape of the laser light L incident on the 4f optical system 441 is adjusted so that the laser light L enters the focusing optical system 404 as parallel light. Specifically, each branched laser light L passes through the first lens 441a and is converged, reflected downward by the mirror 419, diverges via the confocal point O, and passes through the second lens 441b and is converged again to become parallel light. The laser light L then passes through the dichroic mirrors 410 and 438 in order, enters the focusing optical system 404, and is focused on the power meter 700 by the focusing optical system 404.

[0113] The laser processing apparatus 500 may include a surface observation unit 411 for observing the laser light incident surface of the object, and an AF (AutoFocus) unit 412 for finely adjusting the distance between the focusing optical system 404 and the object, in the housing 431. The surface observation unit 411 has an observation light source 411a and a detector 411b.

[0114] Furthermore, the laser processing apparatus 500 is provided with a control unit 450 including a CPU, a ROM, a RAM, etc. for controlling the laser processing apparatus 500. This control unit 450 controls the laser light source 402 and adjusts the output power, pulse width, etc. of the laser light L emitted from the laser light source 402. The control unit 450 also controls the positions of the housing 431 and the stage (not shown), and the driving of the driving unit 432.

[0115] Furthermore, the control unit 450 applies a predetermined voltage to each pixel electrode in the reflective spatial light modulator 403 to display a predetermined modulation pattern (branching pattern) on the liquid crystal layer, thereby modulating (branching) the laser light L as desired in the reflective spatial light modulator 403. Here, the modulation pattern displayed on the liquid crystal layer is generated in advance and stored in the control unit 450. This modulation pattern includes an individual difference correction pattern for correcting individual differences occurring in the laser processing apparatus 500 (for example, distortion occurring in the liquid crystal layer of the reflective spatial light modulator 403), a spherical aberration correction pattern for correcting spherical aberration, etc.

[0116] The laser processing method performed in the laser processing apparatus 500 configured as described above includes a first step of generating a first branching pattern that branches laser light into multiple beams based on a predetermined calculation algorithm, the first branching pattern corresponding to the output target value of each laser light after branching, and setting and displaying the generated first branching pattern on the reflective spatial light modulator 403; a second step of emitting laser light to the reflective spatial light modulator 403 on which the first branching pattern is displayed, and measuring the laser light branched into multiple beams by the first branching pattern with a power meter 700 to derive the actual output value of each laser light after branching; and a third step of generating and outputting a balance parameter related to the generation of the second branching pattern, which is a correction parameter that corrects the calculation algorithm and is a branching pattern that brings the actual output value closer to the output target value. In the second step, a process of measuring the output power during shading is carried out in which a portion of each laser beam after branching is shaded by the shading plate 420 and the output power is measured by the power meter 700. In this process of measuring the output power during shading, the range of the laser beam shaded by the shading plate 420 is changed and the output power is measured by the power meter 700.

[0117] Fig. 22 is a diagram illustrating the output derivation of each laser beam after branching using the power meter 700. Fig. 22(a) shows the branched beam from the reflective spatial light modulator 403 to the power meter 700. Fig. 22(b) shows the position of the light shielding plate 420 provided on the Fourier plane (i.e., the plane including the confocal point O).

[0118] 22(a), the laser light transmitted through the first branching pattern displayed on the liquid crystal layer of the reflective spatial light modulator 403 is branched into multiple beams (three beams in this example) by the first branching pattern. Each branched laser light passes through the first lens 441a and reaches the Fourier plane (a plane including the confocal point O). A light shielding plate 420 is provided on the Fourier plane. The laser light diverging through the confocal point O passes through the second lens 441b and is focused on the power meter 700 by the focusing optical system 404, and the power meter 700 performs output measurement (output measurement processing when the light is blocked).

[0119] Here, in the light-shielded output measurement process, the position of the light-shielded light shielding plate 420 provided on the Fourier plane is continuously changed. For example, as shown in FIG. 22(b), in the first step (STEP 1) of the light-shielded output measurement process, the light-shielded light shielding plate 420 is placed at a position where it does not shield any of the split laser beams (-1st order, 0th order, 1st order). In this case, the power meter 700 measures output data P1 including the outputs of all the laser beams (-1st order, 0th order, 1st order). In the next step (STEP 2), the light-shielded light shielding plate 420 is placed at a position where it shields only the 1st order laser beam among the split laser beams (-1st order, 0th order, 1st order). In this case, the power meter 700 measures output data P2 including the outputs of the two laser beams (-1st order, 0th order). In the final step (STEP 3), the light blocking plate 420 is placed at a position where the 0th and 1st order laser beams out of the branched laser beams (-1st order, 0th order, 1st order) are blocked. In this case, the power meter 700 measures output data P3 including the output of one laser beam (-1st order).

[0120] In this way, by performing measurement with power meter 700 while blocking part of the laser light with light blocking plate 420, it is possible to derive the actual output value of each laser light after branching, since the output ratio of -1st order laser light among all laser lights (-1st order, 0th order, 1st order) is P3 / P1, the output ratio of 0th order laser light is (P2-P3) / P1, and the output ratio of +1st order laser light is (P1-P2) / P1. Note that changing the position of light blocking plate 420 may be performed manually or automatically under the control of control unit 450.

[0121] According to this laser processing method, a laser beam is emitted in a state in which a first branching pattern set according to the output target value of each branched laser beam is set in the reflective spatial light modulator 403. The laser beams branched by the first branching pattern are measured by the power meter 700, and the actual output value of each branched laser beam is derived based on the measurement result. Then, in this laser processing method, a balance parameter related to generation of a second branching pattern that brings the actual output value closer to the output target value is generated and output. According to this configuration, a balance parameter for generating a second branching pattern that brings the actual output value actually measured by the power meter 700 closer to the output target value is generated. In this way, by generating a balance parameter that brings the actually measured output closer to the target value, the calculation algorithm is corrected during the processing process using the balance parameter, and a second branching pattern is generated that can bring the output of the branched beam closer to the output target value than the first branching parameter, thereby appropriately adjusting the output of the branched beam to a desired value. As described above, according to this laser processing method, the output of the branched beam can be adjusted to a desired value, improving processing quality.

[0122] In the second step, an output measurement process during light blocking is performed in which the power meter 700 measures the output while blocking a portion of each of the split laser beams with the light blocking plate 420, and in this output measurement process during light blocking, the power meter 700 measures the output while changing the range of the laser beam blocked by the light blocking plate 420. In this way, the output is measured by the power meter 700 while changing the range of the laser beam blocked by the light blocking plate 420, so that the output of each of the split laser beams can be appropriately derived. [Explanation of symbols]

[0123] 1...laser processing device, 8...light source unit, 9,450...control unit, 17...detection unit, 34,403...reflective spatial light modulator, 100...object, 420...light shielding plate, 700...power meter

Claims

1. A laser processing device that forms a modified region in an object by irradiating the object with laser light, a light source that emits the laser light; a spatial light modulator that modulates the laser light emitted from the light source; a detection unit that detects reflected light of the laser light from the object; a control unit, The control unit a first process of generating a branching pattern for branching the laser beam into a plurality of beams, the first branching pattern corresponding to an output target value of each of the branched laser beams, based on a predetermined calculation algorithm, and setting the generated first branching pattern on the spatial light modulator to display it; a second process of controlling the light source so that the laser light is emitted in a state in which the first branch pattern is displayed on the spatial light modulator; a third process of controlling the detection unit so that the reflected light of each laser beam after branching according to the first branching pattern is detected; a fourth process of deriving an actual output measurement value of each of the branched laser beams based on the detection result by the detection unit, and generating a correction parameter for correcting the calculation algorithm, the correction parameter being related to generation of a second branch pattern that is a branch pattern that brings the actual output value closer to the output target value; a fifth process of correcting the calculation algorithm using the correction parameters, generating the second branch pattern based on the corrected calculation algorithm, and setting and displaying the generated second branch pattern on the spatial light modulator for a processing process.

2. The control unit In the first processing, a plurality of types of the first branching patterns are generated, each of which has a different combination of output target values ​​of each of the branched laser beams; The laser processing device according to claim 1 , wherein the fourth process generates the correction parameter common to at least two of the first branch patterns included in the plurality of types of first branch patterns.

3. The control unit 3. The laser processing device according to claim 2, wherein in the fourth process, the plurality of types of first branch patterns are grouped according to similarity of branch parameters, and the common correction parameters are generated for each group.

4. The control unit 4. The laser processing device according to claim 3, wherein in the fourth process, the grouping is performed according to the degree of approximation of the output target value, which is the branching parameter.

5. The control unit 5. The laser processing device according to claim 3, wherein in the fifth process, information indicating a branching parameter in the processing process is acquired, and the calculation algorithm is corrected using the correction parameter of the group corresponding to the branching parameter.

6. The control unit The laser processing device according to any one of claims 1 to 5, wherein in the first process, the first branching pattern is generated to branch the laser light to different positions in a vertical direction, which is a thickness direction of the object.

7. A laser processing method for forming a modified region in an object by irradiating the object with laser light, comprising: a first step of generating a branching pattern for branching a laser beam into a plurality of beams based on a predetermined calculation algorithm, the first branching pattern corresponding to an output target value of each of the branched laser beams, and setting the generated first branching pattern on a spatial light modulator to display it; a second step of emitting laser light to the spatial light modulator on which the first branching pattern is displayed, and irradiating the target with the laser light branched into a plurality of beams by the first branching pattern; a third step of detecting reflected light from the target of each of the split laser beams; a fourth step of deriving an actual output measurement value of each of the split laser beams based on the detection result of the reflected light, and generating a correction parameter for correcting the calculation algorithm, the correction parameter being related to generation of a second branching pattern that is a branching pattern that brings the actual output value closer to the output target value; a fifth step of correcting the calculation algorithm using the correction parameters, generating the second branch pattern based on the corrected calculation algorithm, and setting and displaying the generated second branch pattern on the spatial light modulator for a processing process.

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