Laser processing device and control method

Abstract

A laser processing device 1 comprises a storage unit for storing a balance parameter that is set for each item of information relating to the position of a focal point and that is a correction parameter for correcting a calculation formula in order to generate a second branch pattern for bringing an actual measured output value of each branch light detected by a detecting unit 17 closer to a target output value, and a control unit 9, wherein the control unit 9 is configured to execute: selection processing for selecting a balance parameter to be applied, on the basis of information relating to the positions of a first focal point, a second focal point, and a third focal point; correction processing for correcting the calculation formula on the basis of the selected balance parameter; and display processing for generating a second branch pattern on the basis of the corrected calculation formula, and setting and displaying the generated second branch pattern in a reflection type spatial light modulator 34 for a processing process.

Description

Laser processing apparatus and control method

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

[0002] In Patent Document 1, based on a predetermined calculation algorithm, a branching pattern for branching laser light into a plurality of beams is generated, and a first branching pattern corresponding to the output target value of each laser beam after branching is generated. A first process of setting and displaying the generated first branching pattern on a spatial light modulator, a second process of controlling a light source so that laser light is emitted in a state where the first branching pattern is displayed on the spatial light modulator, and a third process of controlling a detection unit so that reflected light of each laser beam after branching by the first branching pattern is detected. A fourth process of deriving the output measured value of each laser beam after branching based on the detection result by the detection unit and generating a correction parameter for correcting the calculation algorithm, which is a second branching pattern that is a branching pattern for bringing the output measured value closer to the output target value. And a fifth process of correcting the calculation algorithm by the correction parameter, generating a second branching pattern based on the corrected calculation algorithm, and setting and displaying the generated second branching pattern on the spatial light modulator for the processing process. A laser processing apparatus configured to execute the above is disclosed.

[0003] Japanese Patent Application Laid-Open No. 2022-35948

[0004] Here, the correction parameter is appropriately switched and used according to the processing conditions. From the viewpoint of improving the processing quality, it is important to appropriately select the correction parameter.

[0005] The present disclosure has been made in view of the above circumstances, and an object thereof is to provide a laser processing apparatus and a control method capable of appropriately selecting a correction parameter according to processing conditions and improving processing quality.

[0006] A laser processing apparatus according to one aspect of the present disclosure includes: [1] a laser processing apparatus that forms a modified region on an object by irradiating the object with laser light, comprising: a light source that emits laser light; a spatial light modulator that modulates the laser light to branch into multiple beams by setting a branching pattern of the laser light emitted from the light source; a detection unit that detects reflected light of the laser light on the object; a predetermined calculation algorithm for generating a first branching pattern corresponding to the output target value of each branching beam when branching the laser light into three or more branching beams including a first branching beam, a second branching beam, and a third branching beam; and a predetermined calculation algorithm for generating a second branching pattern that brings the measured output value of each branching beam detected by the detection unit closer to the output target value. A laser processing apparatus comprising: a storage unit that stores correction parameters for correcting the beam, which are set for each piece of information relating to the position of the first focal point of the first branched light, the second focal point of the second branched light, and the third focal point of the third branched light; and a control unit, wherein the control unit is configured to perform a selection process to select the correction parameters to apply based on the information relating to the positions of the first focal point, the second focal point, and the third focal point; a correction process to correct the calculation algorithm based on the selected correction parameters; and a display process to generate a second branching pattern based on the corrected calculation algorithm, and to set and display the generated second branching pattern in a spatial light modulator for the processing process.

[0007] In recent years, when splitting laser light into three or more branched beams, there has been a demand to vary the branching amounts (the spacing between each branched beam) as laser power increases. However, when the spacing between each branched beam is varied, a problem arises when processing is performed using correction parameters generated with a common spacing between each branched beam, resulting in a large error (deviation from the target value) in the output value of each laser beam after branching. In this regard, in a laser processing apparatus according to one aspect of this disclosure, correction parameters are stored for each piece of information relating to the position of the first focal point of the first branched beam, the second focal point of the second branched beam, and the third focal point of the third branched beam. Since the correction parameter is selected according to the information relating to the position of each focal point, even when the spacing between each branched beam is varied, an appropriate correction parameter stored in advance can be selected according to the information relating to the position of each focal point. As a result, the second branched pattern after correction by the correction parameter can be appropriately generated, and the output value of the branched beam can be appropriately brought closer to the output target value. As described above, according to one aspect of the present disclosure, the laser processing apparatus can appropriately select correction parameters according to the processing conditions and improve processing quality.

[0008] A laser processing apparatus according to one aspect of the present disclosure may be [2] "the laser processing apparatus according to [1], wherein the memory unit stores a correction parameter for each branching interval difference, which is the difference between the positions of the first and second focusing points and the difference between the positions of the second and third focusing points, and the control unit selects the correction parameter corresponding to the set branching interval difference in the selection process." The inventors have conducted diligent research and have found that if the branching interval difference is common, the calculation algorithm can be corrected with high accuracy using the same correction parameter even if the conditions of the focusing point (branching conditions) are changed. By using the same correction parameter for focusing point conditions where the branching interval difference is common, the calculation algorithm can be appropriately corrected for various branching conditions while keeping the number of stored correction parameters to the minimum necessary.

[0009] A laser processing apparatus according to one aspect of the present disclosure may be [3] "the laser processing apparatus according to [2], wherein the storage unit stores correction parameters for each branching interval difference for each processing direction in the processing process, and the control unit selects the correction parameter corresponding to the set processing direction and branching interval difference in the selection process." For example, if the correction parameter generated in the processing for the forward pass is used in the processing for the return pass, the error in the output value of the branched light (deviation from the target value) becomes large, which is a problem. In this regard, by storing correction parameters for each processing direction (forward pass, return pass), an appropriate correction parameter can be selected according to the processing direction to appropriately generate a second branching pattern, and the output value of the branched light can be appropriately brought closer to the output target value.

[0010] A laser processing apparatus according to one aspect of the present disclosure may be [4] "a laser processing apparatus according to [2] or [3], wherein the storage unit stores correction parameters for each branching interval difference for each output ratio of the first branched light, the second branched light, and the third branched light, and the control unit selects the correction parameter corresponding to the set output ratio and branching interval difference in the selection process." If the conditions for the output ratio of the branched light differ significantly between the time the correction parameter is generated and the time it is used (during processing), the error (deviation from the target value) in the output value of the branched light becomes large, which is a problem. In this regard, by storing correction parameters for each output ratio of the branched light, an appropriate correction parameter can be selected according to the output ratio of the branched light to appropriately generate the second branching pattern, and the output value of the branched light can be appropriately brought closer to the output target value.

[0011] A laser processing apparatus according to one aspect of the present disclosure may be [5] "a laser processing apparatus according to any one of [1] to [4], wherein the control unit is configured to derive a correction parameter for each piece of information relating to the positions of a first focal point, a second focal point, and a third focal point, and to further execute a derivation process to store the derived correction parameters in a storage unit, and in the derivation process, it generates a first branching pattern based on a calculation algorithm, sets and displays the generated first branching pattern in a spatial light modulator, controls the light source so that laser light is emitted when the first branching pattern is displayed in the spatial light modulator, controls the detection unit so that reflected light from each branched light after branching by the first branching pattern is detected, derives an actual output value for each branched light based on the detection result by the detection unit, generates a correction parameter for generating a second branching pattern that brings the actual output value closer to the target output value, and stores in a storage unit information relating the information relating to the positions of the first focal point, the second focal point, and the third focal point and the generated correction parameters." With this configuration, it is possible to appropriately generate and store correction parameters (correction parameters for each piece of information related to the position of each focal point) based on measured values.

[0012] A control method according to one aspect of the present disclosure is [6] "A control method relating to a spatial light modulator that modulates laser light to be divided into multiple parts by setting a branching pattern of laser light emitted from a light source, comprising: a predetermined calculation algorithm for generating a first branching pattern corresponding to the output target value of each branching light when dividing the laser light into three or more branching lights including a first branching light, a second branching light, and a third branching light; and a correction parameter for correcting the calculation algorithm to generate a second branching pattern that brings the measured output value of each detected branching light closer to the output target value, wherein the first branching of the first branching light The control method includes the steps of: selecting a correction parameter to apply based on information relating to the positions of the first focal point, the second focal point of the second branched light, and the third focal point of the third branched light, under the condition that correction parameters set for each piece of information relating to the positions of the light point, the second focal point of the second branched light, and the third focal point of the third branched light are stored in advance; correcting a calculation algorithm based on the selected correction parameter; 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.

[0013] According to this disclosure, it is possible to improve processing quality by appropriately selecting correction parameters according to processing conditions.

[0014] This is a perspective view of the laser processing apparatus of the embodiment. This is a front view of a part of the laser processing apparatus shown in Figure 1. This is a front view of the laser processing head of the laser processing apparatus shown in Figure 1. This is a side view of the laser processing head shown in Figure 3. This is a diagram of the optical system configuration of the laser processing head shown in Figure 3. This is a plan view for explaining multiple modification spots. This is a diagram showing an example of the GUI setting screen. This is a diagram showing an example of the administrator mode of the GUI setting screen. This is a table showing the error between the design value and the measured value for each output ratio when there are two branches. This is a table showing the error between the design value and the measured value for each output ratio when there are three branches. This is a table showing the error between the design value and the measured value for each output ratio when there are four branches. This is a diagram explaining the configuration of vertical branching. This is a table showing the error between the design value and the measured value for each output ratio when balance parameters obtained without vertical branching are applied to processing with vertical branching (VD16). This is a table showing the error between the design value and the measured value for each output ratio when balance parameters obtained with vertical branching (VD16) are applied to processing with vertical branching (VD16). This is a table showing the relationship between the amount of vertical branching and the maximum error. This is a table showing the error between the design value and the measured value at each output ratio when balance parameters are applied to each region. This is a diagram explaining the operation of balance parameters according to branching parameters. This is a diagram explaining the operation of balance parameters according to branching parameters. This is a flowchart explaining the process of generating branching patterns with balance parameters applied. This is a flowchart explaining the process of generating branching patterns with balance parameters applied. This is a diagram explaining the calculation of balance parameters and the correction of calculation formulas using balance parameters. This is a diagram showing the laser beam when there is a three-point branching with vertical branching. This is a table showing the balance parameter calculation conditions and error measurement conditions. This is a table showing the balance parameter calculation conditions and error measurement conditions. This is a diagram explaining forward and return processing. This is a table showing the error in forward processing and the error in return processing. This is a table showing the error in forward processing and the error in return processing. This is a table explaining the branching interval difference and the operation of balance parameters for each processing direction. This is a table showing the error for each output ratio. This is a table explaining aberration correction for each group. This is a flowchart showing an example of the balance parameter operation flow.This is a table explaining the derivation of balance parameters. This is a flowchart showing another example of the balance parameter operation flow. This is a table explaining the derivation of balance parameters.

[0015] Embodiments of the present invention will be described in detail below with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and redundant descriptions are omitted.

[0016] First, let's explain the basic configuration of a laser processing device.

[0017] [Basic Configuration of Laser Processing Apparatus] As shown in Figure 1, the laser processing apparatus 1 comprises a plurality of moving mechanisms 5, 6, a support unit 7, a pair of laser processing heads 10A, 10B, a light source unit 8, and a control unit 9. In the following description, an example with a pair of laser processing heads will be explained, but 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 direction.

[0018] The moving mechanism 5 has a fixed part 51, a moving part 53, and a mounting 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 mounting part 55 is attached to a rail provided on the moving part 53 and can move along the X direction.

[0019] The moving 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, respectively, relative to the device frame 1a.

[0020] The support portion 7 is attached to a rotating shaft provided on the mounting portion 55 of the moving mechanism 5, and can rotate around an axis parallel to the Z direction as its centerline. In other words, the support portion 7 can move along the X and Y directions and can rotate around an axis parallel to the Z direction as its centerline. The support portion 7 supports the object 100, which is, for example, a wafer.

[0021] As shown in Figures 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 irradiates the object 100 supported by the support portion 7 with laser light L1 while facing the support portion 7 in the Z direction. The laser processing head 10B is attached to the mounting portion 66 of the moving mechanism 6. The laser processing head 10B irradiates the object 100 supported by the support portion 7 with laser light L2 while facing the support portion 7 in the Z direction.

[0022] The light source unit 8 has a pair of light sources 81 and 82. Light source 81 outputs laser light L1. The laser light L1 is emitted from the output section 81a of light source 81 and guided to the laser processing head 10A by the optical fiber 2. Light source 82 outputs laser light L2. The laser light L2 is emitted from the output section 82a of light source 82 and guided to the laser processing head 10B by another optical fiber 2.

[0023] The control unit 9 controls each part of the laser processing apparatus 1 (support unit 7, multiple moving mechanisms 5 and 6, a pair of laser processing heads 10A and 10B, and the light source unit 8, etc.). 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 memory, etc., is executed by the processor, and the reading and writing of data in memory and storage, as well as communication by communication devices, are controlled by the processor. In this way, the control unit 9 realizes various functions.

[0024] An example of processing performed by the laser processing apparatus 1 configured as described above will now be explained. This example of processing involves forming modified regions inside a wafer object 100 along multiple grid-like lines in order to cut the object 100 into multiple chips. The laser processing apparatus 1 may also perform a peeling process to remove a portion of the object 100.

[0025] First, the moving mechanism 5 moves the support portion 7, which supports the object 100, along the X and Y directions, respectively, so that the support portion 7 faces the pair of laser processing heads 10A and 10B in the Z direction. Next, the moving mechanism 5 rotates the support portion 7 with an axis parallel to the Z direction as the center line so that multiple lines extending in one direction on the object 100 are aligned along the X direction.

[0026] Next, the moving 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 beam L1 is located on one line extending in one direction. Meanwhile, the moving mechanism 6 moves the laser processing head 10B along the Y direction so that the focal point of the laser beam L2 is located on another line extending in one direction. Next, the moving mechanism 6 moves the laser processing head 10A along the Z direction so that the focal point of the laser beam L1 is located inside the object 100. Meanwhile, the moving mechanism 6 moves the laser processing head 10B along the Z direction so that the focal point of the laser beam L2 is located inside the object 100.

[0027] Next, the light source 81 outputs laser light L1, causing the laser processing head 10A to irradiate the object 100 with the laser light L1, while the light source 82 outputs laser light L2, causing the laser processing head 10B to irradiate the object 100 with the laser light L2. Simultaneously, the moving mechanism 5 moves the support portion 7 along the X direction so that the focal point of the laser light L1 moves relative to one line extending in one direction, and the focal point of the laser light L2 moves relative to another line extending in one direction. In this way, the laser processing apparatus 1 forms modified regions inside the object 100 along each of the multiple lines extending in one direction within the object 100.

[0028] Next, the moving mechanism 5 rotates the support part 7 with an axis parallel to the Z direction as its centerline so that multiple lines extending in one direction and in other directions perpendicular to it in the object 100 are aligned along the X direction.

[0029] Next, the moving mechanism 6 moves the laser processing head 10A along the Y direction so that the focal point of the laser beam L1 is located on a line extending in another direction. Meanwhile, the moving mechanism 6 moves the laser processing head 10B along the Y direction so that the focal point of the laser beam L2 is located on another line extending in another direction. Next, the moving mechanism 6 moves the laser processing head 10A along the Z direction so that the focal point of the laser beam L1 is located inside the object 100. Meanwhile, the moving mechanism 6 moves the laser processing head 10B along the Z direction so that the focal point of the laser beam L2 is located inside the object 100.

[0030] Next, the light source 81 outputs laser light L1, causing the laser processing head 10A to irradiate the object 100 with the laser light L1, while the light source 82 outputs laser light L2, causing the laser processing head 10B to irradiate the object 100 with the laser light L2. At the same time, the moving 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 a modified region inside the object 100 along each of the multiple lines extending in the object 100 in a direction perpendicular to one direction.

[0031] In the example of processing described above, the light source 81 outputs a laser beam L1 that is penetrating to the object 100, for example, by a pulsed oscillation method, and the light source 82 outputs a laser beam L2 that is penetrating to the object 100, for example, by a pulsed oscillation method. When such laser beams are focused into the object 100, the laser beams are particularly absorbed in the part corresponding to the focal point of the laser beams, and a modified region is formed inside the object 100. The modified region is a region in which the density, refractive index, mechanical strength, and other physical properties differ from the surrounding unmodified region. Examples of modified regions include melting regions, crack regions, dielectric breakdown regions, refractive index change regions, etc.

[0032] When a laser beam output by a pulsed oscillation method is irradiated onto the object 100, and the focal point of the laser beam is moved relative to the object 100 along a line set on the object 100, multiple modified spots are formed so as to be lined up in a row along the line. Each modified spot is formed by irradiation with one pulse of laser beam. 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 movement speed of the focal point of the laser beam relative to the object 100 and the repetition frequency of the laser beam. The shape of the set line is not limited to a grid shape, but may be annular, linear, curved, or a combination of at least one of these shapes.

[0033] [Configuration of the laser processing head] As shown in Figures 3 and 4, the laser processing head 10A comprises a housing 11, an incident section 12, an adjustment section 13, and a focusing section 14.

[0034] 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.

[0035] In the laser processing head 10A, the first wall portion 21 is located on the opposite side of the fixed portion 61 of the moving mechanism 6, and the second wall portion 22 is located on the fixed portion 61 side. The third wall portion 23 is located on the mounting portion 65 side of the moving mechanism 6, and the fourth wall portion 24 is located on the opposite side of the mounting portion 65 and on the laser processing head 10B side (see Figure 2). The fifth wall portion 25 is located on the opposite side of the support portion 7, and the sixth wall portion 26 is located on the support portion 7 side.

[0036] The housing 11 is configured such that it can be attached to the mounting portion 65 with the third wall portion 23 positioned on the mounting portion 65 side of the moving mechanism 6. Specifically, it is as follows: The mounting portion 65 has a base plate 65a and a mounting plate 65b. The base plate 65a is attached to a rail provided on the moving portion 63 (see Figure 2). The mounting plate 65b is erected at the end of the base plate 65a on the side of the laser processing head 10B (see Figure 2). The housing 11 is attached to the mounting portion 65 by screwing bolts 28 into the mounting plate 65b via a base 27 with the third wall portion 23 in contact with the mounting plate 65b. The base 27 is provided on the first wall portion 21 and the second wall portion 22, respectively. The housing 11 is detachable from the mounting portion 65.

[0037] The incident part 12 is attached to the fifth wall 25. The incident part 12 causes the laser beam L1 to enter the housing 11. The incident part 12 is offset towards the second wall 22 side (one of the walls) in the X direction and towards the fourth wall 24 side in the Y direction.

[0038] The inlet section 12 is configured to allow connection of the connection end 2a of the optical fiber 2. The connection end 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 does not have an isolator to suppress reflected light. The isolator is provided in the middle of the fiber, on the side of the light source 81 that is closer to the connection end 2a. This allows for miniaturization of the connection end 2a, and consequently, the inlet section 12. An isolator may be provided at the connection end 2a of the optical fiber 2.

[0039] The adjustment unit 13 is located inside the housing 11. The adjustment unit 13 adjusts the laser beam L1 incident from the incident unit 12. Each component of the adjustment unit 13 is attached to an optical base 29 provided inside the housing 11. The optical base 29 is attached to the housing 11 so as to divide the area inside the housing 11 into an area on the third wall 23 side and an area on the fourth wall 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 24 side. Details of each component of the adjustment unit 13 will be described later.

[0040] The light-gathering unit 14 is positioned on the sixth wall 26. Specifically, the light-gathering unit 14 is positioned on the sixth wall 26 with the hole 26a formed in the sixth wall 26 inserted through it (see Figure 5). The light-gathering unit 14 focuses the laser beam L1, which has been adjusted by the adjustment unit 13, and emits it out of the housing 11. In the X direction, the light-gathering unit 14 is biased towards the second wall 22 side (one of the walls), and in the Y direction, it is biased towards the fourth wall 24 side.

[0041] As shown in Figure 5, the adjustment unit 13 includes an attenuator 31, a beam expander 32, and a mirror 33. The incident unit 12, as well as 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 beam expander 32 are positioned 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.

[0042] 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 imaging optical system 35 of the adjustment unit 13, as well as the light focusing unit 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 on silicon (LCOS) spatial light modulator (SLM). 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 the displayed modulation pattern. The reflective spatial light modulator 34 is configured and displays at least a branching pattern for branching the laser light L1 into multiple beams. 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 Figure 6; details will be described later). The imaging optical system 35 constitutes a bilateral telecentric optical system in which the reflective surface 34a of the reflective spatial light modulator 34 and the entrance pupil surface 14a of the light-gathering unit 14 are in an imaging relationship. The imaging optical system 35 is composed of three or more lenses.

[0043] The straight line A1 and the straight line A2 are located on a plane perpendicular to the Y direction. The straight line A1 is located on the side of the second wall portion 22 (one wall portion side) with respect to the straight line A2. In the laser processing head 10A, the laser beam L1 enters the housing 11 from the incident portion 12 and travels on the straight line A1. After being sequentially reflected by the mirror 33 and the reflective spatial light modulator 34, it travels on the straight line A2 and exits the housing 11 from the condensing portion 14. Note that the order of the arrangement of the attenuator 31 and the beam expander 32 may be reversed. Also, the attenuator 31 may be arranged between the mirror 33 and the reflective spatial light modulator 34. Further, the adjustment unit 13 may have other optical components (for example, a steering mirror or the like arranged in front of the beam expander 32).<MASK>[ <MASK>[

[0044] The laser processing head 10A further includes a dichroic mirror 15, a measurement unit 16, a detection unit 17, a drive unit 18, and a circuit unit 19.<MASK>[ <MASK>[

[0045] The dichroic mirror 15 is arranged on the straight line A2 between the imaging optical system 35 and the condensing portion 14. That is, the dichroic mirror 15 is arranged in the housing 11 between the adjustment unit 13 and the condensing portion 14. The dichroic mirror 15 is attached to the optical base 29 on the side of the fourth wall portion 24. The dichroic mirror 15 transmits the laser beam L1. From the viewpoint of suppressing spherical aberration, the dichroic mirror 15 is preferably, for example, a cube type or two plate types arranged to have a torsional relationship.<MASK>[ <MASK>[

[0046] The measurement unit 16 is arranged in the housing 11 on the side of the first wall portion 21 (the side opposite to one wall portion side) with respect to the adjustment unit 13. The measurement unit 16 is attached to the optical base 29 on the side of the fourth wall portion 24. The measurement unit 16 outputs measurement light L10 for measuring the distance between the surface of the object 100 (for example, the surface on the side where the laser beam L1 enters) and the condensing portion 14, and detects the measurement light L10 reflected by the surface of the object 100 via the condensing portion 14. That is, the measurement light L10 output from the measurement unit 16 is irradiated onto the surface of the object 100 via the condensing portion 14, and the measurement light L10 reflected by the surface of the object 100 is detected by the measurement unit 16 via the condensing portion 14.

[0047] More specifically, the measurement light L10 output from the measurement unit 16 is sequentially reflected by the beam splitter 20 and the dichroic mirror 15 attached to the optical base 29 on the fourth wall portion 24 side, and is emitted from the condensing unit 14 to the outside of the housing 11. The measurement light L10 reflected by the surface of the object 100 enters the housing 11 from the condensing unit 14, is sequentially reflected by the dichroic mirror 15 and the beam splitter 20, enters the measurement unit 16, and is detected by the measurement unit 16.

[0048] The detection unit 17 is disposed inside the housing 11 on the side of the first wall portion 21 (the side opposite to one wall portion side) with respect to the adjustment unit 13. The detection unit 17 is attached to the optical base 29 on the fourth wall portion 24 side. The detection unit 17 outputs observation light L20 for observing the surface of the object 100 (for example, the surface on the side where the laser light L1 is incident), and detects the observation light L20 reflected by the surface of the object 100 via the condensing unit 14. That is, the observation light L20 output from the detection unit 17 is irradiated onto the surface of the object 100 via the condensing unit 14, and the observation light L20 reflected by the surface of the object 100 is detected by the detection unit 17 via the condensing unit 14. The detection unit 17 is, for example, a camera that detects (images) the reflected observation light L20.

[0049] 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 condensing unit 14 to the outside of the housing 11. The observation light L20 reflected by the surface of the object 100 enters the housing 11 from the condensing unit 14, is reflected by the dichroic mirror 15, passes through the beam splitter 20, enters the detection unit 17, and is detected by the detection unit 17. The wavelengths of the laser light L1, the measurement light L10, and the observation light L20 are different from each other (at least the center wavelengths of each are shifted from each other).

[0050] Furthermore, the detection unit 17 detects a portion of the laser light L1 reflected from the surface of the object 100 (details will be described later). The portion of the laser light L1 reflected from the surface of the object 100 is the laser light L1 that is reflected in small amounts towards the detection unit 17 by the dichroic mirror 15 from the surface of the object 100.

[0051] The drive unit 18 is attached to the optical base 29 on the fourth wall portion 24 side. The drive unit 18 moves the light-gathering portion 14, which is located on the sixth wall portion 26, along the Z direction, for example, by the driving force of a piezoelectric element.

[0052] The circuit unit 19 is located within the housing 11, on the third wall 23 side relative to the optical base 29. In other words, the circuit unit 19 is located within the housing 11, on the third wall 23 side relative to the adjustment unit 13, measurement unit 16, and 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. For 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 kept constant (i.e., the distance between the surface of the object 100 and the focusing point of the laser beam L1 is kept constant). The housing 11 is provided with a connector (not shown) to which wiring for electrically connecting the circuit unit 19 to the control unit 9 (see Figure 1), etc., is connected.

[0053] The laser processing head 10B, like the laser processing head 10A, comprises a housing 11, an incident section 12, an adjustment section 13, a focusing section 14, a dichroic mirror 15, a measuring section 16, a detection section 17, a drive section 18, and a circuit section 19. However, as shown in Figure 2, the components of the laser processing head 10B are arranged to be symmetrical with the components of the laser processing head 10A with respect to a virtual plane that passes through the midpoint between a pair of mounting sections 65 and 66 and is perpendicular to the Y direction.

[0054] For example, the housing (first housing) 11 of the laser processing head 10A is attached to the mounting portion 65 such 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 such 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.

[0055] The housing 11 of the laser processing head 10B is configured such that it can be attached to the mounting portion 66 with the third wall portion 23 positioned on the mounting portion 66 side. Specifically, it is as follows: 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 movable 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.

[0056] [Laser beam branching] The following describes the branching of laser beam for the purpose of cutting and peeling the target object 100, with reference to Figures 6 to 8. As described above, the laser beam L1 is branched according to the branching pattern set and displayed in the reflective spatial light modulator 34.

[0057] Figure 6 illustrates the multiple modification spots SA when the laser beam L1 is split into four. In the example shown in Figure 6, the laser beam L1 is split so that multiple (four) modification spots SA are formed on the object 100, arranged in a line along an inclined direction C2 that is inclined with respect to the orthogonal direction perpendicular to the processing direction C1. The splitting of the laser beam L1 is achieved by a splitting pattern (modulation pattern) set and displayed on a reflective spatial light modulator 34 (see Figure 5).

[0058] In the illustrated example, the laser beam L1 is split into four, forming four modified spots SA. Of the four split modified spots SA, the distance between adjacent pairs of modified spots SA in the processing direction C1 is the branching pitch BPx, and the distance between them in the direction perpendicular to the processing direction C1 is the branching pitch BPy. For pairs of modified spots SA formed by irradiation with two consecutive pulses of laser beam L1, the distance between them in the processing direction C1 is the pulse pitch PP. The angle between the processing direction C1 and the inclination direction C2 is the branching angle α.

[0059] Figure 7 shows the setting screen of GUI 111 for realizing the branching of the laser beam L1 as shown in Figure 6. GUI 111 functions as an input unit that accepts input from the user. The setting screen of GUI 111 shown in Figure 7 includes a processing condition selection button 211 for selecting processing conditions, a branch count 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 to move to the next processing line after laser processing along one processing line, an image diagram 214 for inputting or displaying the branch count and index, a processing Z height field 215 for inputting the position of the modification 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 the method for switching processing conditions.

[0060] The processing condition selection button 211 allows you 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 will automatically move in the index direction by the amount of the input value. If the number of branches is greater than 1, the laser processing head 10A will automatically move in the index direction by the amount of the index calculated by the following formula: Index = (Number of branches) × Index input value

[0061] The diagram 214 includes an index input value display unit 214a and an output input field 214b for inputting the output of each modification spot SA.

[0062] Figure 8 shows an example of the administrator mode of the GUI 111 settings screen. The settings screen shown in Figure 8 includes a branch direction selection button 221 for selecting the branching 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 column number input field 224 for inputting the number of columns of branch pitch BPx, a branch pitch input field 225 for inputting the branch pitch BPy, an index field 226 for inputting the index, an optical axis image diagram 227 based on the number of branches, a forward / return path selection button 228 for selecting whether the scanning direction of the laser beam L1 is one direction (forward path) or the other direction (return path), and a balance adjustment start button 229 for automatically adjusting the balance of various values.

[0063] [Branching Pattern Correction Processing] In the laser processing apparatus 1 according to this embodiment, prior to the processing process (processing process) that forms a modified region on the object 100, a first branching pattern is generated based on a predetermined calculation formula (calculation algorithm) according to the output ratio (output target value) of each laser beam after branching. With the first branching pattern displayed on the reflective spatial light modulator 34, laser light is emitted onto the object 100, the reflected light of each laser beam after branching according to the first branching pattern is detected, and the measured output value of each laser beam after branching is derived based on the detection result. Balance parameters (correction parameters) related to the generation of a second branching pattern that brings the measured output value closer to the desired output ratio (output target value) are generated. During the processing, the calculation formula is corrected by the above 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.

[0064] Thus, in the laser processing apparatus 1 according to this embodiment, the first branching pattern generated based on a predetermined calculation formula is not used directly during processing. Instead, before processing, the measured output values ​​of each laser beam after branching using the first branching pattern are derived, and balance parameters for generating a second branching pattern are generated to reduce the error between the output setting value based on the assumed output ratio and the measured output value. During processing, the calculation formula is corrected using these balance parameters, and the second branching pattern generated from the corrected calculation formula is used. This allows the output of the branched beam to be appropriately adjusted to a desired value (output ratio), thereby improving processing quality.

[0065] The aforementioned error before correction (the error between the output setting value based on the assumed output ratio and the measured output value) is caused by factors such as the optical characteristics of the spatial light modulator itself, the different transmission regions of each branched light in the lens, or individual differences in optical elements.

[0066] Figure 9 is a table showing the error between the measured value and the design value (ideal output ratio) for each output ratio at two branching points. The left side of Figure 9 shows the error when the first branching pattern described above is used without correction by balance parameters. As shown in the left side of Figure 9, when correction by balance parameters is not performed, for example, when the design value of the output ratio at two branching points is 20:80 the measured value is 9:91 (error 11%), when the design value is 30:70 the measured value is 21:79 (error 9%), when the design value is 40:60 the measured value is 35:65 (error 5%), when the design value is 50:50 the measured value is 51:49 (error 1%), and when the design value is 60:40 the measured value is 65:35 (error 5%). The error is particularly large when the difference in output between the two branched points is large.

[0067] The laser processing apparatus 1 generates balance parameters that bring the measured output value closer to the design value (ideal output ratio) based on error information as shown in the left diagram of Figure 9. These balance parameters correct the calculation formula that generates the branching pattern, enabling the generation of a second branching pattern (a branching pattern that brings the measured output value closer to the design value) using the corrected calculation formula. The right diagram of Figure 9 shows the error when the second branching pattern generated after correction by the balance parameters is used. In the example shown in the right diagram of Figure 9, the error at each output ratio is reduced, and the maximum error is reduced to 3%, because the second branching parameter generated by applying the balance parameters, i.e., by correcting the calculation formula with the balance parameters, is used. Note that Figure 9 shows the error when the first branching pattern is set to a condition without vertical branching, and when the processing process using the second branching pattern is also set to a condition without vertical branching.

[0068] The effect of generating and applying balance parameters is not limited to two-point branching, but is similar for other branching configurations. Figure 10 is a table showing the error between the design value and the measured value for each output ratio in the case of three-point branching. Figure 11 is a table showing the error between the design value and the measured value for each output ratio in the case of four-point branching. As shown in the left figure of Figure 10, if no correction by balance parameters is performed, the maximum error for each output ratio in the case of three-point branching is 8%, but as shown in the right figure of Figure 10, by applying balance parameters, the maximum error for each output ratio in the case of three-point branching is reduced to 3%. Also, as shown in the left figure of Figure 11, if no correction by balance parameters is performed, the maximum error for each output ratio in the case of four-point branching is 9%, but as shown in the right figure of Figure 11, by applying balance parameters, the maximum error for each output ratio in the case of four-point branching is reduced to 3%.

[0069] The laser processing apparatus 1 may generate a first branching pattern that performs vertical branching, which branches the laser beam to different positions in the Z direction (vertical direction), which is the thickness direction of the object 100. Figure 12 is a diagram illustrating the form of vertical branching. Figure 12(a) shows each laser beam when there is three branching without vertical branching, and Figure 12(b) shows each laser beam when there is three branching with vertical branching. In Figures 12(a) and 12(b), the horizontal axis is the processing direction, and the vertical axis is the Z direction (vertical direction). As shown in Figure 12(a), in the state without vertical branching, each of the branched laser beams is irradiated at the same height in the Z direction. On the other hand, as shown in Figure 12(b), in the state with vertical branching, each of the branched laser beams is irradiated at different heights in the Z direction. Note that "Vertical branch VD0" in Figure 12(a) means there is no vertical branch, and "Vertical branch VD16" in Figure 12(b) means there is a vertical branch and the branch pitch in the Z direction is 16μ.

[0070] Figure 13 is a table showing the error between the measured values ​​and the design values ​​for each output ratio at three branching points when balance parameters obtained without vertical branching are applied to machining with vertical branching (VD16). The left side of Figure 13 shows the error when the first branching pattern without vertical branching is used. The right side of Figure 13 shows the error when machining with vertical branching (VD16) is performed using the second branching parameter, which is generated by correcting with balance parameters generated based on the error information for the case without vertical branching as shown in the left side of Figure 13. As described above, in both the processing using the first branching pattern and the machining processing applying the second branching pattern, when vertical branching is absent, the maximum error at three branching points could be reduced to 3%, as shown in the right side of Figure 10. On the other hand, when a balance parameter was generated using a first branching pattern without vertical branching, and a second branching pattern was generated by applying a correction based on this balance parameter, and machining with vertical branching (VD16) was performed using this pattern, the maximum error was 4%, as shown in the right-hand figure of Figure 13. Thus, it is conceivable that if the conditions for balance parameter generation and vertical branching during machining differ from each other, applying the balance parameter may not sufficiently reduce the error between the design value and the measured value.

[0071] Figure 14 is a table showing the error between the measured values ​​and the design values ​​for each output ratio at three branching points when balance parameters obtained with vertical branching (VD16) are applied to machining with vertical branching (VD16). In both the processing using the first branching pattern and the machining processing applying the second branching pattern, by using vertical branching (VD16), the maximum error could be reduced to 3%, as shown in the right-hand figure of Figure 14. In this way, by standardizing the conditions for balance parameter generation and vertical branching in machining, the error between the measured values ​​and the design values ​​can be sufficiently reduced.

[0072] Figure 15 is a table showing the relationship between the amount of vertical branching and the maximum error. In Figure 15, "amount of vertical branching" refers to the amount of vertical branching in the machining process. In Figure 15, "maximum error" refers to the maximum error at a certain output ratio when the vertical branching shown in "amount of vertical branching" is performed using balance parameters generated based on the first branching pattern of VD16. As shown in Figure 16, when balance parameters generated based on the first branching pattern of VD16 are applied, the maximum error is minimized (0.8%) when the branching process of VD16 is performed. Also, as shown in Figure 16, when the branching process of VD2 is performed using balance parameters generated based on the first branching pattern of VD16, the maximum error is also relatively small at 1.4%. Thus, even if the balance parameter generation and the conditions for vertical branching in the machining process do not match, when machining with vertical branching is performed, the error can be reduced by using balance parameters generated under the conditions for vertical branching.

[0073] The laser processing apparatus 1 may generate multiple types of first branching patterns in which the combinations of output ratios (target output values) of each laser beam after branching are different from each other, and generate common balance parameters for these multiple types of first branching patterns. Here, for example, if common balance parameters for each output ratio are generated so as to reduce (for example minimize) the error between the design value and the measured value in region A (the region enclosed by the solid rectangle) shown in the left diagram of Figure 16, then as shown in the left diagram of Figure 16, the error in region A becomes small, less than 1%, but the errors in regions B (the region enclosed by the dashed rectangle) and C (the region enclosed by the dashed rectangle), which are different from region A, become large, ranging from 3% to 6%. Thus, balance parameters generated to reduce the error in a certain region cannot sufficiently reduce the error in regions far from that region.

[0074] Therefore, the laser processing apparatus 1 may group the output ratio (target output value), which is a branching parameter, according to the degree of approximation, and generate a common balance parameter for each group. In other words, the laser processing apparatus 1 may generate a common balance parameter for each group (region) in which the output ratios are similar. The right-hand figure of Figure 16 shows the error in a three-point branching when one common balance parameter is generated for each region A, B, and C. As shown in the right-hand figure of Figure 16, when a common balance parameter is generated for each region A, B, and C, the error between the design value and the measured 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 measured value can be reduced.

[0075] The functions of the control unit 9, which implements the branch pattern correction process described above, will be explained in detail below.

[0076] The control unit 9 is configured to perform the following processes: first process, generating a first branching pattern that splits the laser beam into multiple beams based on a predetermined calculation formula (calculation algorithm), corresponding to the output ratio (target output value) of each laser beam after branching; setting and displaying the generated first branching pattern on the reflective spatial light modulator 34; second process, controlling the light source unit 8 so that the laser beam is emitted when the first branching pattern is displayed on the reflective spatial light modulator 34; third process, controlling the detection unit 17 so that the reflected light of each laser beam after branching by the first branching pattern is detected; fourth process, deriving the measured output value of each laser beam after branching based on the detection result by the detection unit 17, and generating balance parameters (correction parameters) related to the generation of a second branching pattern, which is a correction parameter that corrects the calculation formula and brings the measured output value closer to a desired output ratio (target output value); and fifth process, correcting the calculation formula using the balance parameters, 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.

[0077] In the first process, the control unit 9 determines the output ratio based on the information received on the GUI 111 setting screen (see Figures 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 a first branching pattern corresponding to the output ratio based on a pre-stored calculation formula (calculation algorithm). The control unit 9 may generate multiple types of first branching patterns in which the combination of output ratios of each laser beam after branching is different from each other. The control unit 9 may also generate a first branching pattern that performs vertical branching, which branches the laser beam to different positions in the Z direction (vertical direction), which is the thickness direction of the object 100.

[0078] In the second process, the control unit 9 controls the light source unit 8 so that, when the first branching pattern is displayed on the reflective spatial light modulator 34, the laser light is irradiated to the object 100 at an output (below the modification threshold) such that no modified region is formed on the object 100. Alternatively, the branched laser light may be irradiated to an object other than the object 100 that will be laser processed after the branching pattern correction process (an object for the correction process).

[0079] In the third process, the control unit 9 controls the detection unit 17 so that it is possible to detect (image) the reflected light from each of the branched laser beams on the object 100, at least during the period when each of the branched laser beams is irradiating the object 100. The control unit 9 acquires the image captured by the detection unit 17 from the detection unit 17.

[0080] In the fourth process, the control unit 9 estimates (derives) the measured output value of each laser beam based on the brightness of each point corresponding to each laser beam after branching in the imaging data acquired by the detection unit 17. The control unit 9 generates balance parameters related to the generation of a second branching pattern that brings the measured output value closer to a desired output ratio, as correction parameters to correct the calculation formula. If multiple types of first branching patterns are generated, the control unit 9 generates common correction parameters for at least two of the multiple types of first branching patterns. The control unit 9 may generate common correction parameters for all first branching patterns, or it may group the multiple types of first branching patterns according to the degree of approximation of the branching parameters and generate common balance parameters for each group. Branching parameters include, for example, the number of branches, the output ratio (target output value), the amount of vertical branching, and the individual aberration correction amount. In the example shown in Figure 16, the control unit 9 groups the branching parameters according to the degree of approximation of the output ratio and generates balance parameters for each group of region A, region B, and region C.

[0081] In the fifth process, the control unit 9 performs the following processes: correcting the calculation formula with balance parameters and generating a second branching pattern based on the corrected calculation formula; and setting and displaying the second branching pattern in the reflective spatial light modulator 34 during the processing process. The control unit 9 may also acquire information indicating the branching parameters in the processing process and correct the calculation formula using the balance parameters of the group corresponding to the branching parameters. Figures 17 and 18 illustrate the operation of balance parameters according to branching parameters. For example, the control unit 9 may acquire information indicating the number of branches as information indicating the branching parameters in the processing process based on information received on the setting screen of the GUI 111 (see Figures 7 and 8), identify balance parameters according to the number of branches as shown in Figure 17, and correct the calculation formula using the identified balance parameters. Figure 17 shows that if the number of branches is 2, the balance parameters for 2-point branching are reflected in the calculation formula; if the number of branches is 3, the balance parameters for 3-point branching are reflected in the calculation formula; and if the number of branches is 4, the balance parameters for 4-point branching are reflected in the calculation formula.

[0082] The control unit 9 may, for example, acquire information indicating the output ratio as information indicating branching parameters in the machining process based on the information received on the GUI 111 setting screen (see Figures 7 and 8), identify balance parameters corresponding to the output ratio, and correct the calculation formula using the identified balance parameters. For example, suppose that balance parameters for each of the three regions (region A, region B, and region C) corresponding to the output ratio are generated, as shown in Figure 16. In this case, as shown in Figure 18, the control unit 9 may, for example, reflect the balance parameters of region A (balance parameter list A shown in Figure 18) in the calculation formula when the output ratio is included in region A, and reflect the balance parameters of region B (balance parameter list B shown in Figure 18) in the calculation formula when the output ratio is included in region B.

[0083] Next, the process of generating branch patterns with balance parameters applied will be explained with reference to Figures 19 and 20. Figures 19 and 20 are flowcharts illustrating the process of generating branch patterns with balance parameters applied. Figure 19 shows an example of using one balance parameter, while Figure 20 shows an example of switching between multiple balance parameters.

[0084] As shown in Figure 19, first, a first branch pattern is derived based on the information (design values) received on the GUI 111 settings screen, and this first branch pattern is set and displayed on the reflective spatial light modulator 34 (Step S1: First step).

[0085] Next, the laser beam L1 is emitted from the reflective spatial light modulator 34 displaying the first branching pattern, and the laser beam, which has been branched into multiple beams by the first branching pattern, is irradiated onto the object 100, thus initiating laser irradiation (Step S2: Second step).

[0086] Next, the reflected light from the branched light from the object 100 is detected (imaged) by the detection unit 17 (Step S3: Third step).

[0087] Next, based on the imaging data (results of reflected light detection), the measured output values ​​of each laser beam after branching are derived, and balance parameters are generated from the error between the measured output values ​​and the desired output ratio (target output value, design value) (Step S4: fourth step).

[0088] Finally, the calculation formula is corrected by the balance parameter, a second branching pattern is generated based on the corrected calculation formula, and the generated second branching pattern is set and displayed in the reflective spatial light modulator 34 for the processing process (step S5: fifth step).

[0089] Next, with reference to Figure 20, an example of operating by switching between multiple balance parameters will be described. As shown in Figure 20, the processing in steps S11 to S14 is the same as the processing in steps S1 to S4 in Figure 19. However, in step S14, multiple types of first branch patterns are grouped according to the degree of approximation of the branch parameters, and balance parameters are generated for each group.

[0090] Then, information indicating branching parameters in the machining process (machining conditions) is acquired, and the balance parameters are switched based on the machining conditions (e.g., output ratio) (step S15). In other words, a balance parameter that matches the machining conditions is selected from among multiple balance parameters.

[0091] Finally, the calculation formula is corrected by the selected balance parameters, a second branching pattern is generated based on the corrected calculation formula, and the generated second branching pattern is set and displayed in the reflective spatial light modulator 34 for the processing process.

[0092] The laser processing apparatus 1 according to this embodiment is a laser processing apparatus that forms a modified region on an object 100 by irradiating the object 100 with laser light, and comprises 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 the reflected light of the laser light on the object 100, and a control unit 9. The control unit 9 generates a branching pattern that branches the laser light into multiple parts based on a predetermined calculation formula, and a first branching pattern corresponding to the output target value of each laser light after branching, and sets and displays the generated first branching pattern on the reflective spatial light modulator 34, and when the first branching pattern is displayed on the reflective spatial light modulator 34, The system is configured to perform the following steps: a second process of controlling the light source unit 8 so that laser light is emitted; a third process of controlling the detection unit 17 so that the reflected light of each laser beam after branching according to the first branching pattern is detected; a fourth process of deriving the measured output value of each laser beam after branching based on the detection result by the detection unit 17, and generating balance parameters related to the generation of a second branching pattern, which is a correction parameter that corrects the calculation formula and brings the measured output value closer to the target output value; and a fifth process of correcting the calculation formula using the balance parameters, generating a second branching pattern based on the corrected calculation formula, and setting and displaying the generated second branching pattern in the reflective spatial light modulator 34 for the processing process.

[0093] In the laser processing apparatus 1 according to this embodiment, laser light is emitted while a first branching pattern, generated according to the output target value of each laser beam after branching, is displayed on the reflective spatial light modulator 34. Reflected light from the object 100 is detected, and the measured output value of each laser beam is derived based on the detection result. Then, in this laser processing apparatus 1, a balance parameter for generating a second branching pattern that brings the measured output value closer to the output target value is generated. The second branching pattern is generated by a calculation formula corrected by the balance parameter, and the second branching pattern is displayed on the reflective spatial light modulator 34 for the processing process. With this configuration, a balance parameter is generated for generating a second branching pattern that brings the measured output value, which is estimated with high accuracy based on the actually detected reflected light, closer to the output target value. During the processing process, the calculation formula is corrected by the balance parameter, and a second branching pattern is generated that can bring the output of the branched light closer to the output target value than the first branching parameter, thereby appropriately adjusting the output of the branched light to a desired value. As described above, the laser processing apparatus 1 according to this embodiment can adjust the output of the branched light to a desired value and improve processing quality.

[0094] In the first process, the control unit 9 generates multiple types of first branching patterns in which the combination of output target values ​​for each laser beam after branching is different from each other, and in the fourth process, it may generate a common balance parameter for at least two of the multiple types of first branching patterns. In this way, by generating a common balance parameter for multiple first branching patterns in which the output target value conditions are different from each other, 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 the case in which a balance parameter is generated for each first branching pattern.

[0095] In the fourth process, the control unit 9 may group multiple types of first branching patterns according to the degree of approximation of their balance parameters and generate a common balance parameter for each group. For example, if a single common balance parameter is generated for all first branching patterns, even if the calculation formula is corrected using the generated common balance parameter, the accuracy of all second branching patterns (the accuracy of bringing the output of the branched light closer to the output target value) cannot be sufficiently improved, especially if the first branching patterns have significantly different branching parameters. In this regard, if a common balance parameter is generated for each group of branches with similar branching parameters, that is, if different balance parameters are generated for groups with different branching parameters, the accuracy of the second branching patterns (the accuracy of bringing the output of the branched light closer to the output target value) can be ensured.

[0096] In the fourth processing step, the control unit 9 may group the data according to the degree of approximation of the output target value, which is a branching parameter. This ensures that a common balance parameter is generated for each group whose output target value is similar, thereby guaranteeing the accuracy of the second branching pattern (the accuracy of bringing the output of the branched light closer to the output target value).

[0097] In the fifth process, the control unit 9 may acquire information indicating branching parameters in the machining process and correct the calculation formula using the balance parameters of the group corresponding to the branching parameters. This allows the machining process to be performed by displaying a second branching pattern generated by a calculation formula corrected with balance parameters suitable for the branching parameters in the machining process, thereby improving machining quality.

[0098] The control unit 9 may generate a first branching pattern in the first process that branches the laser beam to different positions in the vertical direction, which is the thickness direction of the object 100. In actual processing, the laser beam may be branched to different positions in the vertical direction (vertical branching). By generating the first branching pattern related to such vertical branching, it is possible to generate balance parameters for generating a second branching pattern that can appropriately bring the output of the branched light in the case of vertical branching closer to the output target value.

[0099] [Calculation formula, balance parameters, and correction of calculation formula] Next, the calculation formula (calculation algorithm), balance parameters, and correction of the calculation formula by the balance parameters will be explained. First, the "predetermined calculation formula (calculation algorithm)" in this embodiment is a calculation formula that generates the first branching pattern, and is a calculation formula that outputs a control voltage to each pixel electrode in order to display the first branching pattern on the reflective spatial light modulator 34, based on information on how to branch the laser light (information that can identify the three-dimensional coordinates of the focal point of each branched light) and the initial target value of the output ratio of each branched light. Furthermore, the "corrected predetermined calculation formula (calculation algorithm)" is a calculation formula that generates the second branching pattern, and is a calculation formula that outputs a control voltage to each pixel electrode in order to display the second branching pattern on the reflective spatial light modulator 34, based on information on how to branch the laser light and the target value of the output ratio of each branched light, which is the initial target value corrected by balance parameters calculated based on measured values. Thus, the initial "predetermined calculation formula (calculation algorithm)" that generates the first branching pattern is corrected to the "corrected predetermined calculation formula (calculation algorithm)" that generates the second branching pattern by correcting the target values ​​of the output ratio of each branched light from the initial target values ​​to the corrected target values. When correcting the target values ​​of the output ratio of each branched light as described above, a balance parameter calculated based on measured values ​​is used.

[0100] Figure 21 illustrates the calculation of balance parameters and the correction of calculation formulas using balance parameters. The calculation of balance parameters and the correction of calculation formulas using balance parameters (i.e., correction of target values) are performed as follows as an example.

[0101] Firstly, as shown in Figure 21, the relationship between the target value and the measured value of the output ratio of each branched light is derived and approximated (fitted) by a function. That is, the processes from the first to the third processes described above are performed while varying the "initial target value of the output ratio of each branched light" for generating the first branching pattern, thereby determining the relationship between the target value and the measured value of the output ratio of each branched light, as shown in Figure 21, and fitting it with a function (for example, a cubic function f(x)).

[0102] Secondly, the following equation (1), which is the inverse function of the cubic function f(x) shown in Figure 21, is derived. In equation (1) below, the coefficients a', b', c', and d' are examples of balance parameters. In other words, deriving an inverse function like equation (1) means calculating (generating) the balance parameters. x: f(-1)(y) = a'y3 + b'y2 + c'y + d' ... (1)

[0103] (1) By substituting the initial target value as the value of y into the inverse function shown in equation (1), an x ​​value is derived such that the measured value y becomes the initial target value, and this x value is taken as the corrected target value. This process corresponds to correcting the calculation formula.

[0104] [Operation of Balance Parameters According to Branching Conditions] Next, the operation of balance parameters according to branching conditions will be explained with reference to Figures 22 to 36.

[0105] Figure 22 shows the laser beam when vertical branching occurs at three points. In Figure 22, the horizontal direction is the processing direction, and the vertical direction is the Z direction (vertical direction). As shown in Figure 22, when vertical branching occurs, the branched light is irradiated at different heights in the Z direction. In the following, the first focal point, which is the lowest (farthest from the light source) in the Z direction, may be described as the lower point X1, the second focal point, which is one position above the lower point X1, as the midpoint X2, and the third focal point, which is the highest (closest to the light source) in the Z direction, as the upper point X3. In addition, the difference (spacing) between the upper point X3 and the midpoint X2 may be described as the upper-midpoint spacing VD1, and the difference (spacing) between the lower point X1 and the midpoint X2 may be described as the mid-lower spacing VD2.

[0106] In a three-point branching system with vertical branching, configurable parameters include, for example, the processing direction, vertical branching amount, Y-shift amount (the shift amount in the Y-direction as described above), power ratio, and spherical aberration (CP) correction value. Among these parameters, conventionally, the vertical branching amount has been set to the same value for the upper-intermediate spacing VD1 and the middle-lower spacing VD2. However, in recent years, with the increase in laser power, there has been a growing demand to set the upper-intermediate spacing VD1 and the middle-lower spacing VD2 to different values. For example, when there are three focusing points, lower point X1, middle point X2, and upper point X3, when processing the middle point X2, it is necessary to bring the middle point X2 closer to the lower point X1 in order to connect it with the upper crack from the modified region of the lower point X1. However, when processing the upper point X3, the upper crack related to the processing of the middle point X2 has extended considerably, so the crack can be connected even if the distance between the upper point X3 and the middle point X2 (upper-intermediate spacing VD1) is widened. Thus, in stealth dicing, processing conditions are often selected where the upper intermediate spacing VD1 > middle and lower spacing VD2, and there is a demand to set the upper intermediate spacing VD1 and the middle and lower spacing VD2 to different values.

[0107] As described above with reference to Figures 13 to 16, even if the conditions for balance parameter generation and vertical branching during machining do not match, if machining with vertical branching is performed, the error in the output ratio relative to the design value can be reduced by using the balance parameters generated under the conditions with vertical branching. However, detailed studies by the inventors have shown that the conditions under which such errors can be reduced are limited to certain conditions. Figure 23 is a table showing the balance parameter calculation (generation) conditions and the error measurement (machining) conditions. As shown in Figure 23(a), let's assume that balance parameter calculation (generation) is performed under the conditions that the upper-intermediate spacing VD1 = 2 μm and the middle-lower spacing VD2 = 2 μm. In this case, as shown in Figure 23(b), even if the processing conditions during machining are different from those used when calculating (generating) the balance parameters, such as when the upper intermediate spacing VD1 = 16 μm and the middle-lower spacing VD2 = 16 μm, if the branch spacing difference, which is the difference between the upper intermediate spacing VD1 and the middle-lower spacing VD2, is the same (in this case, the branch spacing difference is 0 in both cases), the maximum error of the output ratio relative to the design value could be kept to about 3 P (points). Here, P (points) represents the difference in percentage. On the other hand, as shown in Figure 23(c), when the processing conditions are different, such as when the upper intermediate spacing VD1 = 16 μm and the middle-lower spacing VD2 = 20 μm, and the branch spacing difference, which is the difference between the upper intermediate spacing VD1 and the middle-lower spacing VD2, is a different value (in this case, the branch spacing difference is 0 when calculating the balance parameters, and -4 when processing), the maximum error of the output ratio relative to the design value increased to about 10 P. Thus, if the conditions for balance parameter generation and vertical branching during processing do not match, the error in the output ratio can be reduced if the branching interval difference is common to both, but it is considered that the error in the output ratio cannot be sufficiently reduced if the branching interval difference is not common to both.

[0108] As shown in Figure 24(a), when the balance parameters are calculated (generated) under the conditions of upper-intermediate spacing VD1 = 20 μm, middle-lower spacing VD2 = 16 μm, and branch spacing difference 4 μm, as shown in Figure 24(b), the processing conditions are different from those used during balance parameter calculation (generation) except for "Condition 3". However, since the branch spacing difference is set to 4 μm in all cases, the maximum error of the output ratio relative to the design value can be kept to about 1.5 P. Also, as shown in Figure 24(c), when the balance parameters are calculated (generated) under the conditions of upper-intermediate spacing VD1 = 16 μm, middle-lower spacing VD2 = 20 μm, and branch spacing difference -4 μm, as shown in Figure 24(d), the processing conditions are different from those used during balance parameter calculation (generation) except for "Condition 8". However, since the branch spacing difference is set to -4 μm in all cases, the maximum error of the output ratio relative to the design value can be kept to about 2.1 P. On the other hand, as shown in Figure 24(e), when the branching interval difference is set to 2 μm, which is different from the value used when calculating (generating) the balance parameters, the maximum error in the output ratio relative to the design value becomes large at 6.9 P. Therefore, it is preferable that the balance parameters be stored for each branching interval difference and selected according to the conditions of the branching interval difference (details will be described later).

[0109] Furthermore, detailed studies by the inventors revealed that it is necessary to select balance parameters considering whether the laser beam is scanning in the forward or return direction. Figure 25(a) shows forward machining with three branching with vertical branching, and Figure 25(b) shows return machining with three branching with vertical branching. As shown in Figures 25(a) and 25(b), the machining directions of forward and return machining are different. Now, for example, suppose that balance parameters are calculated (generated) under forward machining conditions, and these balance parameters are used during both forward and return machining. In this case, as shown in Figure 26(a), the maximum error of the output ratio relative to the design value in forward machining could be kept to about 3P, but as shown in Figure 26(b), the maximum error of the output ratio relative to the design value in return machining was large, at about 4 percent. The factors that contribute to the large error when the forward and return paths differ include the asymmetry of the LCOS of the reflective spatial light modulator 34, and the asymmetry of the pattern displayed on the LCOS (three-branch pattern, reciprocal switching of X-shift).

[0110] Figure 27(a) is a table showing the maximum error of the output ratio relative to the design value when the balance parameter is calculated (generated) under forward machining conditions and used under forward machining conditions. Figure 27(b) is a table showing the maximum error of the output ratio relative to the design value when the balance parameter is calculated (generated) under return machining conditions and used under return machining conditions. As shown in Figures 27(a) and 27(b), by unifying the forward / return conditions during balance parameter calculation and machining, the maximum error relative to the design value could be reduced to about 3P. From the above, it can be said that it is preferable for the balance parameter to be stored not only for each branching interval difference as described above, but also for each forward / return (i.e., machining direction) and selected according to the branching interval difference and machining direction conditions.

[0111] Figure 28 is a table illustrating the balance parameter operation for each branching interval difference and machining direction. Figure 28(a) is a table illustrating the balance parameter operation for the comparative example. In the balance parameter operation for the comparative example, for example, under the conditions that the branching interval difference is 0 and the machining is performed in the forward direction, only one balance parameter, Parameter 1, is used. In this case, when machining using balance parameter Parameter 1, the error can be kept to 3P or less under the same conditions (branching interval difference 0 and forward direction machining), but the error becomes large at 4P when the branching interval difference is 0 and the machining is performed in the return direction, and the error becomes extremely large at 10P or more under other conditions. For conditions where the error is 10P or more, it is difficult to perform machining using balance parameter Parameter 1 (the use of Parameter 1 is not possible).

[0112] Figure 28(b) is a table illustrating the balance parameter operation according to this embodiment. In the balance parameter operation according to this embodiment, unique balance parameters: Parameters 1 to 10 are used for each combination of branching interval difference and machining direction. As a result, an appropriate balance parameter is selected according to the combination of branching interval difference and machining direction, so that the maximum error of the output ratio relative to the design value can be significantly reduced compared to the comparative example.

[0113] Furthermore, the balance parameters may be stored not only for each branching interval difference and machining direction as described above, but also for each output ratio (more specifically, for each group of similar output ratios), and selected according to the conditions of the branching interval difference, machining direction, and output ratio. As shown in Figure 29(a), there are regions A, B, and C according to the degree of approximation of the output ratio, and the balance parameters are calculated (generated) under the output ratio conditions of region A, and these balance parameters are used not only for region A but also for machining in regions B and C. In this case, the maximum error in region A is about 3P, while the maximum errors in regions B and C are larger, about 6P. In contrast, as shown in Figure 29(b), there are regions A, B, and C according to the degree of approximation of the output ratio, and the balance parameters calculated in region A are used for machining in region A, the balance parameters calculated in region B are used for machining in region B, and the balance parameters calculated in region C are used for machining in region C, in which case the maximum error in each region could be kept to about 3P.

[0114] Furthermore, as shown in Figure 30, the balance parameters may be stored not by output ratio, but by aberration (e.g., spherical aberration CP), or more specifically, by groups of similar spherical aberration CP. Here, we use spherical aberration, but the balance parameters may also be stored for astigmatism, coma aberration, or a combination thereof. As shown in Figure 30, spherical aberration can be applied individually to each branched light.

[0115] The following section will describe in detail the functions of the control unit 9, which enables the operation of balance parameters according to the branching conditions described above.

[0116] The control unit 9 functions as a control unit that controls each part of the laser processing apparatus 1, and also functions as a storage unit that stores calculation formulas (calculation algorithms) and balance parameters for generating branching patterns. In this embodiment, the control unit 9 is described as also functioning as a storage unit that stores balance parameters, etc., but a separate storage unit may be provided in addition to the control unit 9.

[0117] The control unit 9 stores a predetermined calculation formula (calculation algorithm) for generating a first branching pattern corresponding to the output target value of each branching beam when branching the laser beam into three or more branching beams, including a first branching beam, a second branching beam, and a third branching beam (in this example, three branching beams).

[0118] The control unit 9 stores balance parameters used to correct a calculation formula (calculation algorithm) in order to generate a second branching pattern that brings the measured output values ​​of each branched light detected by the detection unit 17 closer to the target output value. The control unit 9 stores balance parameters set for each piece of information relating to the position of the first focal point of the first branched light (for example, the lower point X1 shown in Figure 22), the second focal point of the second branched light (for example, the midpoint X2 shown in Figure 22), and the third focal point of the third branched light (for example, the upper point X3 shown in Figure 22). Specifically, the control unit 9 stores balance parameters for each branching interval difference, which is the difference (interval) between the upper point X3 and the midpoint X2, and the difference (interval) between the lower point X1 and the midpoint X2, which is the difference in branching interval differences. In the following explanation, it will be assumed that the control unit 9 stores balance parameters for each branching interval difference, but for example, balance parameters may be stored for each piece of information indicating the position of each focal point.

[0119] The control unit 9 may store balance parameters for each branching interval difference for each machining direction in the machining process (forward path / return path). The control unit 9 may also store balance parameters for each branching interval difference for each output ratio of the first branching light, the second branching light, and the third branching light (for example, for each region of groups with similar output ratios).

[0120] The control unit 9 is configured to perform selection processing, correction processing, and display processing, assuming that it has stored the balance parameters for each branch interval difference as described above.

[0121] In the selection process, the control unit 9 selects the balance parameters to be applied based on information relating to the positions of the first, second, and third focusing points. Specifically, the control unit 9 identifies the branching interval difference (the difference between the upper-intermediate interval VD1 and the middle-lower interval VD2) set during machining, and selects the balance parameters corresponding to this branching interval difference.

[0122] In the selection process, the control unit 9 may further specify the machining direction set during machining, and select balance parameters corresponding to the machining direction and the difference in branching intervals.

[0123] In the selection process, the control unit 9 may further specify the output ratio of the branched light set during processing and select balance parameters corresponding to the output ratio and the branching interval difference. Specifically, when regions are set for each group with similar output ratios, the control unit 9 may specify the region and select balance parameters corresponding to the region and the branching interval difference.

[0124] The control unit 9 corrects the calculation formula (calculation algorithm) based on the selected balance parameter during the correction process.

[0125] In the display process, the control unit 9 generates a second branching pattern based on the calculation formula (calculation algorithm) corrected in the correction process, and sets the generated second branching pattern in the reflective spatial light modulator 34 for the processing process and displays it.

[0126] The control unit 9 may further perform a derivation process to derive a balance parameter for each piece of information relating to the positions of the first, second, and third focusing points (specifically, for each difference in branch intervals) and store the derived balance parameters. In other words, the control unit 9 may start by deriving the balance parameters.

[0127] The control unit 9 may perform the following actions in the derivation process: generate a first branching pattern based on a calculation formula (calculation algorithm), set and display the generated first branching pattern on the reflective spatial light modulator 34, control the light source unit 8 so that laser light is emitted when the first branching pattern is displayed on the reflective spatial light modulator 34, control the detection unit 17 so that the reflected light of each branched light after branching by the first branching pattern is detected, derive the measured output value of each branched light based on the detection result by the detection unit 17, generate balance parameters for generating a second branching pattern that brings the measured output value closer to the target output value, and store information relating the positions of the first, second, and third focal points (specifically, the difference in branching intervals) to the generated balance parameters.

[0128] Next, we will explain the balance parameter operation flow. Figure 31 is a flowchart showing an example of the balance parameter operation flow, and it is a diagram showing the operation flow when the balance parameter is stored for each branch interval difference and machining direction.

[0129] As shown in Figure 31, a branching pattern (first branching pattern) is generated using a calculation formula based on the design value (target value) of the output, and the output ratio is measured on the actual machine (step S101). Subsequently, balance parameters are derived from the error between the design value and the measured value for each condition (here, the branching interval difference and each machining direction) (step S102).

[0130] Next, the balance parameters for each obtained condition are input into the pattern generation software and managed (step S103). Subsequently, based on the branching interval difference and processing direction (reciprocal information) according to the recipe input into the GUI, the corresponding balance parameters are selected, and the calculation formula is corrected by these balance parameters to generate the second branching pattern (step S104).

[0131] Figure 32 is a diagram illustrating the derivation of balance parameters in the flow shown in Figure 31. As shown in Figure 32(a), the error measurement described above is performed for each combination of branching interval difference and machining direction, and based on the measurement results, balance parameters are derived for each combination of branching interval difference and machining direction, as shown in Figure 32(b).

[0132] Figure 33 is a flowchart showing another example of the balance parameter operation flow, illustrating the operation flow when balance parameters are stored for each region of branching interval, machining direction, and output ratio. As shown in Figure 33, a branching pattern (first branching pattern) is generated using a calculation formula based on the design value (target value) of the output, and the output ratio is measured on the actual machine (step S201). Subsequently, balance parameters are derived from the error between the design value and the measured value for each condition (here, for each region of branching interval difference, machining direction, and output ratio) (step S202).

[0133] Next, the balance parameters for each obtained condition are input into the pattern generation software and managed (step S203). Subsequently, based on the branching interval difference, processing direction (reciprocal information), and output ratio range according to the recipe input into the GUI, the corresponding balance parameters are selected, and the calculation formula is corrected by these balance parameters to generate the second branching pattern (step S204).

[0134] Figure 34 illustrates the derivation of balance parameters in the flow shown in Figure 32. As shown in Figure 34(a), for example, for region A of the output ratio, the above-described error measurement is performed for each combination of branching interval difference and machining direction, and based on the measurement results, as shown in Figure 34(b), balance parameters for each combination of branching interval difference and machining direction related to region A of the output ratio are derived. Similarly, as shown in Figure 34(c), for example, for region B of the output ratio, the above-described error measurement is performed for each combination of branching interval difference and machining direction, and based on the measurement results, as shown in Figure 34(d), balance parameters for each combination of branching interval difference and machining direction related to region B of the output ratio are derived.

[0135] Next, the operation and effects of the laser processing apparatus 1 according to this embodiment will be described.

[0136] The laser processing apparatus 1 according to this embodiment is a laser processing apparatus that forms a modified region on an object 100 by irradiating the object 100 with laser light, and comprises a light source unit 8 that emits laser light, a reflective spatial light modulator 34 that modulates the laser light to branch into multiple beams by setting a branching pattern of the laser light emitted from the light source unit 8, a detection unit 17 that detects the reflected light of the laser light on the object 100, a predetermined calculation formula for generating a first branching pattern according to the output target value of each branching beam when branching the laser light into three or more branching beams including a first branching beam, a second branching beam, and a third branching beam, and a second branching pattern that brings the measured output value of each branching beam detected by the detection unit 17 closer to the output target value. The system includes a storage unit (control unit 9) that stores balance parameters used to correct the calculation formula in order to achieve the first branched light, balance parameters set for each piece of information relating to the position of the first focal point of the first branched light, the second focal point of the second branched light, and the third focal point of the third branched light, and the control unit 9 is configured to perform a selection process to select the balance parameters to apply based on the information relating to the positions of the first focal point, the second focal point, and the third focal point; a correction process to correct the calculation formula based on the selected balance parameters; and a display process to generate a second branching pattern based on the corrected calculation formula, and to set and display the generated second branching pattern in the reflective spatial light modulator 34 for the processing process.

[0137] In recent years, when splitting laser light into three or more branched beams, there has been a demand to vary the branching amounts (the spacing between each branched beam) as laser power increases. However, when the spacing between each branched beam is varied, a problem arises when processing is performed using a balance parameter generated with a common spacing between each branched beam, resulting in a large error (deviation from the target value) in the output value of each laser beam after branching. In this regard, the laser processing apparatus 1 according to this embodiment stores balance parameters for each piece of information relating to the position of the first focal point of the first branched beam, the second focal point of the second branched beam, and the third focal point of the third branched beam. Since the balance parameter is selected according to the information relating to the position of each focal point, even when the spacing between each branched beam is varied, an appropriate balance parameter stored in advance can be selected according to the information relating to the position of each focal point. This makes it possible to appropriately generate a second branching pattern after correction by the balance parameter, and to appropriately bring the output value of the branched beam closer to the output target value. As described above, the laser processing apparatus 1 according to this embodiment can appropriately select balance parameters according to the processing conditions and improve processing quality.

[0138] The laser processing apparatus 1 according to this embodiment stores a balance parameter for each branching interval difference, which is the difference between the positions of the first and second focusing points and the difference between the positions of the second and third focusing points. The control unit 9 may select a balance parameter corresponding to the set branching interval difference during the selection process. The inventors have conducted diligent research and found that if the branching interval difference is common, the calculation formula can be corrected with high accuracy using the same balance parameter even if the conditions of the focusing point (branching conditions) are changed. By using the same balance parameter for focusing point conditions where the branching interval difference is common, the calculation formula can be appropriately corrected for various branching conditions while keeping the number of stored balance parameters to the minimum necessary.

[0139] In this embodiment, the laser processing apparatus 1 stores balance parameters for each branching interval difference for each processing direction in the processing process, and the control unit 9 may select the balance parameter corresponding to the set processing direction and branching interval difference in the selection process. For example, if the balance parameter generated in the processing for the forward pass is used in the processing for the return pass, the error in the output value of the branched light (deviation from the target value) becomes large, which is a problem. In this regard, by storing balance parameters for each processing direction (forward pass, return pass), an appropriate balance parameter can be selected according to the processing direction to appropriately generate the second branching pattern, and the output value of the branched light can be appropriately brought closer to the output target value.

[0140] In this embodiment, the laser processing apparatus 1 stores balance parameters for each branching interval difference for each output ratio of the first branched light, the second branched light, and the third branched light. The control unit 9 may select the balance parameter corresponding to the set output ratio and branching interval difference during the selection process. If the conditions for the output ratio of the branched light differ significantly between the time the balance parameter is generated and the time it is used (during processing), a problem arises in that the error (deviation from the target value) in the output value of the branched light becomes large. In this regard, by storing balance parameters for each output ratio of the branched light, an appropriate balance parameter can be selected according to the output ratio of the branched light to appropriately generate the second branching pattern, and the output value of the branched light can be appropriately brought closer to the output target value.

[0141] 1... Laser processing device, 8... Light source unit, 9... Control unit, 17... Detection unit, 34... Reflective spatial light modulator, 100... Object.

Claims

1. A laser processing apparatus for forming a modified region on an object by irradiating the object with laser light, comprising: a light source that emits the laser light; a spatial light modulator that modulates the laser light to branch into multiple parts by setting a branching pattern of the laser light emitted from the light source; a detection unit that detects the reflected light of the laser light on the object; a predetermined calculation algorithm for generating a first branching pattern corresponding to the output target value of each branching light when branching the laser light into three or more branching lights including a first branching light, a second branching light, and a third branching light; a correction parameter for correcting the calculation algorithm to generate a second branching pattern that brings the measured output value of each branching light detected by the detection unit closer to the output target value, the correction parameter being set for each piece of information relating to the position of the first focal point of the first branching light, the second focal point of the second branching light, and the third focal point of the third branching light; and a control unit, wherein the control unit is: A laser processing apparatus configured to perform: a selection process to select the correction parameters to apply based on information relating to the positions of the first, second, and third focal points; a correction process to correct the calculation algorithm based on the selected correction parameters; and a display process to generate the second branching pattern based on the corrected calculation algorithm, and to set and display the generated second branching pattern in the spatial light modulator for the processing process.

2. The laser processing apparatus according to claim 1, wherein the storage unit stores a correction parameter for each branching interval difference, which is the difference between the positions of the first focusing point and the second focusing point and the difference between the positions of the second focusing point and the third focusing point, and the control unit selects the correction parameter corresponding to the set branching interval difference in the selection process.

3. The laser processing apparatus according to claim 2, wherein the storage unit stores the correction parameters for each branching interval difference for each processing direction in the processing process, and the control unit selects the correction parameters corresponding to the set processing direction and branching interval difference in the selection process.

4. The laser processing apparatus according to claim 2, wherein the storage unit stores the correction parameters for each branching interval difference for each output ratio of the first branched light, the second branched light, and the third branched light, and the control unit selects the correction parameters corresponding to the set output ratio and branching interval difference in the selection process.

5. The control unit is configured to further perform a derivation process which involves deriving the correction parameter for each piece of information relating to the positions of the first, second, and third focal points, and storing the derived correction parameter in the storage unit, wherein the derivation process involves generating the first branching pattern based on the calculation algorithm, setting and displaying the generated first branching pattern on the spatial light modulator, controlling the light source so that the laser light is emitted when the first branching pattern is displayed on the spatial light modulator, controlling the detection unit so that the reflected light of each branched light after branching by the first branching pattern is detected, deriving the measured output value of each branched light based on the detection result by the detection unit, generating the correction parameter for generating the second branching pattern which brings the measured output value closer to the target output value, and storing information in the storage unit which associates the information relating to the positions of the first, second, and third focal points with the generated correction parameter.

6. A control method for a spatial light modulator that modulates a laser beam emitted from a light source to split it into multiple beams by setting a branching pattern of the laser beam, comprising: a predetermined calculation algorithm for generating a first branching pattern corresponding to the output target value of each branching beam when splitting the laser beam into three or more branching beams including a first branching beam, a second branching beam, and a third branching beam; and correction parameters for correcting the calculation algorithm to generate a second branching pattern that brings the measured output value of each detected branching beam closer to the output target value, wherein the correction parameters are set for each piece of information relating to the position of the first focal point of the first branching beam, the second focal point of the second branching beam, and the third focal point of the third branching beam, under the condition that these are stored in advance, the method comprises: selecting the correction parameters to apply based on the information relating to the positions of the first focal point, the second focal point, and the third focal point; and correcting the calculation algorithm based on the selected correction parameters. A control method comprising the steps of generating the second branching pattern based on the corrected calculation algorithm, and setting and displaying the generated second branching pattern in the spatial light modulator for a processing process.

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