JP7730643B2 - Laser processing device and laser processing method - Google Patents

Description

The present invention relates to a laser processing device and a laser processing method.

Patent Document 1 describes a laser processing device equipped with a laser light source, a spatial light modulator, and a focusing correction means different from the spatial light modulator. This type of laser processing device performs operations such as dividing and peeling an object by forming a modified region inside the object (wafer) through irradiation with laser light. The technology described in Patent Document 1 not only forms a modified region inside the object through irradiation with laser light, but also captures an image of a portion of the light reflected from the focusing point, detects the amount of positional deviation of the focusing point based on the image capture result, and adjusts the modulation pattern in the spatial light modulator to minimize the positional deviation.

Patent No. 6620976

In laser processing devices such as those described above, a branching pattern is set in the spatial light modulator so that multiple modified regions are formed simultaneously, and the laser light is branched according to this branching pattern. The branching pattern is set, for example, according to the target output value of each branched laser light. Here, when branching laser light using a spatial light modulator, for example, the output of each branched laser light may not reach the target output value (design value) described above due to the optical characteristics of the spatial light modulator itself, optical characteristics such as different transmission regions of each branched light in the lens, or individual differences in optical elements. This phenomenon is difficult to completely avoid. If the output of each branched laser light does not reach the expected value, the amount of crack extending from the modified region may not be the desired amount, resulting in the target object not being divided or peeled (deteriorating processing quality).

The present invention aims to provide a laser processing device and a laser processing method that can improve processing quality by adjusting the output of branched light to a desired value.

A laser processing device according to one aspect of the present invention is a laser processing device that forms a modified region in an object by irradiating the object with laser light, and includes a light source that emits laser light, a spatial light modulator that modulates the laser light emitted from the light source, a detection unit that detects reflected light of the laser light from the object, and a control unit. The control unit performs a first process of generating a branching pattern that branches the laser light into multiple beams based on a predetermined calculation algorithm, a first branching pattern that corresponds to the output target value of each branched laser beam, setting and displaying the generated first branching pattern on the spatial light modulator, and controlling the light source so that laser light is emitted when the first branching pattern is displayed on the spatial light modulator. a third process of controlling the detection unit so that reflected light of each laser beam after branching by the first branching pattern is detected; a fourth process of deriving an actual output value of each laser beam after branching based on the detection results by the detection unit and generating correction parameters for correcting the calculation algorithm and for generating a second branching pattern, which is a branching pattern that brings the actual output value closer to the output target value; and a fifth process of correcting the calculation algorithm using the correction parameters, generating a second branching pattern based on the corrected calculation algorithm, and setting the generated second branching pattern on a spatial light modulator for use in the processing process and displaying it.

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

In the first process, the control unit may generate multiple types of first branching patterns with different combinations of output target values for each branched laser beam, and in the fourth process, generate common correction parameters for at least two of the multiple types of first branching patterns. In this way, by generating common correction parameters for multiple first branching patterns with different output target value conditions, it becomes possible to generate unique second branching patterns using the same correction parameters, which simplifies the process of generating and managing the correction parameters compared to generating correction parameters for each first branching pattern.

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

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

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

In the first process, the control unit may generate a first branching pattern that branches the laser light to different positions in the vertical direction, which is the thickness direction of the object. During actual processing, the laser light may branch to different positions in the vertical direction (vertical branching). By generating a first branching pattern related to this vertical branching, it is possible to generate correction parameters related to the generation of a second branching pattern that can appropriately bring the output of the branched light when branched vertically closer to the output target value.

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

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

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

In the laser processing method according to the other aspect described above, the second step involves performing a light-shielding output measurement process in which a portion of each split laser beam is blocked by a light-shielding plate while measuring the output with a power meter. In this light-shielding output measurement process, the power meter may measure the output while changing the range of laser beams blocked by the light-shielding plate. In this way, by measuring the output with each power meter while changing the range of laser beams blocked by the light-shielding plate, the output of each split laser beam can be appropriately derived.

According to the present invention, processing quality can be improved by adjusting the output of the branched light to a desired value.

1 is a perspective view of a laser processing apparatus according to an embodiment; FIG. 2 is a front view of a portion of the laser processing apparatus shown in FIG. 1 . FIG. 2 is a front view of a laser processing head of the laser processing apparatus shown in FIG. 1 . FIG. 4 is a side view of the laser processing head shown in FIG. 3 . FIG. 4 is a configuration diagram of an optical system of the laser processing head shown in FIG. 3. FIG. 2 is a plan view illustrating a plurality of modified spots. FIG. 10 is a diagram illustrating an example of a GUI setting screen. FIG. 10 is a diagram illustrating an example of an administrator mode of a GUI setting screen. 10 is a table showing the error of the actual measured value from the design value at each output ratio when branching at two points. 10 is a table showing the error of the actual measured value from the design value at each output ratio when branching at three points. 10 is a table showing the error of the actual measured value from the design value at each output ratio when branching at four points. FIG. 10 is a diagram illustrating a vertical branching mode. 10 is a table showing the error of the actual measured value from the design value at each output ratio when the balance parameters acquired without vertical branching are applied to machining with vertical branching (VD16). 10 is a table showing the error of the actual measured value from the design value at each output ratio when the balance parameters acquired with vertical branching (VD16) are applied to machining with vertical branching (VD16). 10 is a table showing the relationship between the amount of vertical branching and the maximum error. 10 is a table showing the error of the actual measurement value from the design value at each output ratio when a balance parameter is applied to each region. FIG. 10 is a diagram illustrating the operation of balance parameters according to branch parameters. FIG. 10 is a diagram illustrating the operation of balance parameters according to branch parameters. 10 is a flowchart illustrating a process of generating a branch pattern to which a balance parameter is applied. 10 is a flowchart illustrating a process of generating a branch pattern to which a balance parameter is applied. FIG. 10 is a schematic configuration diagram of a laser processing device according to a modified example. 10A and 10B are diagrams illustrating the output derivation of each laser beam after branching using a power meter.

Embodiments of the present invention will now be described in detail with reference to the drawings. Note that identical or equivalent parts in each drawing will be designated by the same reference numerals, and duplicate explanations will be omitted.

First, we will explain the basic configuration of a laser processing device.

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

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

The movement mechanism 6 has a fixed part 61, a pair of moving parts 63 and 64, and a pair of mounting parts 65 and 66. The fixed part 61 is attached to the device frame 1a. Each of the pair of moving parts 63 and 64 is attached to a rail provided on the fixed part 61, and 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 both the Y direction and the Z direction relative to the device frame 1a.

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

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

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

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

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

First, the movement mechanism 5 moves the support unit 7 supporting the object 100 in both the X and Y directions so that the support unit 7 faces the pair of laser processing heads 10A, 10B in the Z direction. Next, the movement mechanism 5 rotates the support unit 7 around an axis parallel to the Z direction so that multiple lines extending in one direction on the object 100 are aligned along the X direction.

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

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

Next, the movement mechanism 5 rotates the support part 7 around an axis parallel to the Z direction as its center line so that multiple lines extending in another direction perpendicular to the one direction on the object 100 are aligned along the X direction.

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

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

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

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

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

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.

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

The housing 11 is configured so that it can be attached to the mounting portion 65 of the movement mechanism 6 with the third wall portion 23 positioned on the mounting portion 65 side. Specifically, 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 movement portion 63 (see Figure 2). The mounting plate 65b is erected at the end of the base plate 65a on the laser processing head 10B side (see Figure 2). The housing 11 is attached to the mounting portion 65 by threading the bolts 28 into the mounting plate 65b via the pedestals 27 with the third wall portion 23 in contact with the mounting plate 65b. The pedestals 27 are provided on both the first wall portion 21 and the second wall portion 22. The housing 11 is detachable from the mounting portion 65.

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

The incident section 12 is configured to allow connection to 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 return light. The isolator is provided midway along the fiber, closer to the light source 81 than the connection end 2a. This allows for the miniaturization of the connection end 2a and, ultimately, the incident section 12. Note that an isolator may also be provided at the connection end 2a of the optical fiber 2.

The adjustment unit 13 is disposed within the housing 11. The adjustment unit 13 adjusts the laser light L1 incident from the incident unit 12. Each component of the adjustment unit 13 is attached to an optical base 29 provided within the housing 11. The optical base 29 is attached to the housing 11 so as to divide the area within the housing 11 into an area on the third wall 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.

The focusing unit 14 is disposed on the sixth wall 26. Specifically, the focusing unit 14 is disposed on the sixth wall 26, inserted through a hole 26a formed in the sixth wall 26 (see Figure 5). The focusing unit 14 focuses the laser light L1 adjusted by the adjustment unit 13 and emits it outside the housing 11. The focusing unit 14 is biased toward the second wall 22 (one of the walls) in the X direction, and toward the fourth wall 24 in the Y direction.

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

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 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 (LCOS: Liquid Crystal on Silicon) 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 a displayed modulation pattern. At least a branching pattern for branching the laser light L1 into multiple beams is set and displayed on the reflective spatial light modulator 34. As a result, the laser light L1 incident on the reflective spatial light modulator 34 is branched into multiple laser beams in the reflective spatial light modulator 34 (see Figure 6; details will be described later). The imaging optical system 35 constitutes a double-telecentric optical system in which the reflecting surface 34a of the reflective spatial light modulator 34 and the entrance pupil plane 14a of the light-collecting unit 14 are in an imaging relationship. The imaging optical system 35 is composed of three or more lenses.

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

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.

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

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

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

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

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 exits the housing 11 from the condenser 14. The observation light L20 reflected from the surface of the object 100 enters the housing 11 from the condenser 14, is reflected by the dichroic mirror 15, passes through the beam splitter 20, and enters the detection unit 17, where it is detected. Note that the wavelengths of the laser light L1, measurement light L10, and observation light L20 are different from one another (at least their respective center wavelengths are shifted from one another).

The detection unit 17 also detects a portion of the laser light L1 reflected by the surface of the object 100 (details will be described later). The portion of the laser light L1 reflected by the surface of the object 100 is the laser light L1 that is reflected by the dichroic mirror 15 in the direction of the detection unit 17, in a small amount.

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 collecting unit 14 arranged on the sixth wall portion 26 along the Z direction, for example, by using the driving force of a piezoelectric element.

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

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

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

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

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

Figure 6 is a diagram illustrating multiple modified spots SA when laser light L1 is split into four. In the example shown in Figure 6, the laser light L1 is split so that multiple (four) modified spots SA are formed on the target object 100, aligned in a tilt direction C2 that is tilted relative to the orthogonal direction perpendicular to the processing direction C1. The splitting of the laser light L1 is achieved by a splitting pattern (modulation pattern) set and displayed on the reflective spatial light modulator 34 (see Figure 5).

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

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

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

The image diagram 214 includes an index input value display section 214a and an output input column 214b for inputting the output of each modified spot SA.

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

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

In this way, with the laser processing device 1 according to this embodiment, the first branching pattern generated based on a predetermined formula is not used as is during processing. Instead, before processing, the actual measured output values of each laser beam after branching when using the first branching pattern are derived, and balance parameters related to generating a second branching pattern that reduces the error between the expected output ratio and the actual measured output values are generated. During processing, the formula is corrected using the balance parameters, and the second branching pattern generated from the corrected formula is used. This allows the output of the branched beam to be appropriately adjusted to the desired value (output ratio), improving processing quality.

The above-mentioned error before correction (the difference between the expected output ratio and the actual measured output value) is caused by, for example, the optical characteristics of the spatial light modulator itself, the optical characteristics of the lens, such as the different transmission areas of each branched light, or individual differences in the optical elements.

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

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

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

The laser processing apparatus 1 may generate a first branching pattern that performs vertical branching, branching the laser light 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 vertical branching. Figure 12(a) shows each laser light when branching at three points without vertical branching, and Figure 12(b) shows each laser light when branching at three points with vertical branching. In Figures 12(a) and 12(b), the horizontal axis represents the processing progress direction, and the vertical axis represents the Z direction (vertical direction). As shown in Figure 12(a), without vertical branching, each branched laser light is irradiated at the same height in the Z direction. On the other hand, as shown in Figure 12(b), with vertical branching, each branched laser light is irradiated at different heights in the Z direction. Note that "Vertical branch VD0" in Figure 12(a) means that there is no vertical branch, and "Vertical branch VD16" in Figure 12(b) means that there is vertical branch and the branch pitch in the Z direction is 16μ.

Figure 13 is a table showing the error of the actual measured value from the design value at each output ratio with three-point branching when balance parameters obtained without vertical branching are applied to processing with vertical branching (VD16). The left diagram of Figure 13 shows the error when the first branching pattern without vertical branching is used. The right diagram of Figure 13 shows the error when processing with vertical branching (VD16) is performed using second branching parameters generated by correction using balance parameters generated based on error information for the case without vertical branching, as shown in the left diagram of Figure 13. As described above, when both processing using the first branching pattern and processing applying the second branching pattern were performed without vertical branching, the maximum error was reduced to 3% with three-point branching, as shown in the right diagram of Figure 10. On the other hand, when balance parameters were generated using a first branch pattern without vertical branching, and corrections were made using those balance parameters to generate a second branch pattern, which was then used to perform machining with vertical branching (VD16), the maximum error was 4%, as shown in the right diagram of Figure 13. As such, when the conditions for balance parameter generation and vertical branching in machining differ, it is thought that applying the balance parameters may not be able to sufficiently reduce the error of the actual measured value from the design value.

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

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

The laser processing apparatus 1 may generate multiple types of first branching patterns with different combinations of output ratios (output target values) for each branched laser beam, and may generate a common balance parameter for the multiple types of first branching patterns. For example, if a common balance parameter for each output ratio is generated to reduce (e.g., minimize) the error of the actual measured value from the design value within region A (the region surrounded by a solid-line rectangle) shown in the left diagram of FIG. 16, as shown in the left diagram of FIG. 16, the error in region A will be reduced to 1% or less, but the errors in region B (the region surrounded by a dash-dotted rectangle) and region C (the region surrounded by a dashed-line rectangle), which are different from region A, will be increased to 3% to 6%. Thus, a balance parameter generated to reduce the error in a certain region cannot sufficiently reduce the error in regions distant from that region.

For this reason, the laser processing device 1 may group the laser beams according to the degree of similarity of the output ratio (output target value), which is a branching parameter, and generate a common balance parameter for each group. In other words, the laser processing device 1 may generate a common balance parameter for each group (region) with similar output ratios. The right diagram in Figure 16 shows the error in a three-point branch when a common balance parameter is generated for each of regions A, B, and C. As shown in the right diagram in Figure 16, when a common balance parameter is generated for each of regions A, B, and C, the error between the design value and the actual 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 actual measured value can be reduced.

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

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

In the first process, the control unit 9 determines the output ratio based on information received on the setting screen of the GUI 111 (see 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 that have different combinations of output ratios of the laser beams after branching. The control unit 9 may also generate a first branching pattern that performs vertical branching, branching the laser beam to different positions in the Z direction (vertical direction), which is the thickness direction of the object 100.

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

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

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

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

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

Next, the process of generating a branch pattern to which balance parameters are applied will be described with reference to Figures 19 and 20. Figures 19 and 20 are flowcharts explaining the process of generating a branch pattern to which balance parameters are applied. Figure 19 shows an example of using one balance parameter, while Figure 20 shows an example of using multiple balance parameters by switching between them.

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

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

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

Next, the actual output value of each branched laser beam is calculated based on the imaging data (detection results of reflected light), and a balance parameter is generated from the error between the actual output value and the desired output ratio (output target value, design value) (Step S4: Fourth Process).

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

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

Then, information indicating the 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, balance parameters that match the machining conditions are selected from multiple balance parameters.

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

Next, we will explain the effects of the laser processing device 1 according to this embodiment.

The laser processing device 1 according to this embodiment is a laser processing device that forms a modified region in an object 100 by irradiating the object 100 with laser light, and is equipped with 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 from the object 100, and a control unit 9. The control unit 9 performs a first process of generating a branching pattern that branches the laser light into multiple beams based on a predetermined formula, a first branching pattern that corresponds to the output target value of each branched laser beam, setting the generated first branching pattern on the reflective spatial light modulator 34 and displaying it, and a second process of displaying the first branching pattern on the reflective spatial light modulator 34 when the first branching pattern is displayed on the reflective spatial light modulator 34. 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 reflected light of each laser light after branching by the first branching pattern is detected; a fourth process of deriving an actual output value of each branched laser light based on the detection results by the detection unit 17 and generating a balance parameter related to generating a second branching pattern, which is a branching pattern that is a correction parameter for correcting the calculation formula and brings the actual output value closer to the output target value; and a fifth process of correcting the calculation formula using the balance parameter, generating a second branching pattern based on the corrected calculation formula, and setting and displaying the generated second branching pattern on the reflective spatial light modulator 34 for the processing process.

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

In the first process, the control unit 9 may generate multiple types of first branching patterns having different combinations of output target values for each branched laser beam, and in the fourth process, 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 having different output target value conditions, it becomes possible to generate unique second branching patterns using the same balance parameter, which simplifies the generation and management of balance parameters compared to generating a balance parameter for each first branching pattern.

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

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

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

In the first process, the control unit 9 may generate a first branching pattern that branches the laser light to different positions in the vertical direction, which is the thickness direction of the object 100. During actual processing, the laser light may be branched to different positions in the vertical direction (vertical branching). By generating a first branching pattern related to this vertical branching, it is possible to generate balance parameters related to the generation of 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.

Although the above describes an embodiment, the present invention is not limited to the above embodiment. For example, a method of measuring the output of each laser beam after branching for generating a balance parameter (correction parameter) has been described in which the reflected light from the target is detected by a detection unit, but the present invention is not limited to this. Specifically, the output of each laser beam after branching for generating a balance parameter may be measured by a power meter. Below, an embodiment using a power meter will be described with reference to Figures 21 and 22.

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

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

The 4f optical system 441 adjusts the wavefront shape of the laser light L modulated by the reflective spatial light modulator 403 and includes a first lens 441a and a second lens 441b. The first lens 441a and the second lens 441b are arranged on the optical path between the reflective spatial light modulator 403 and the focusing optical system 404 such that the optical path distance between the reflective spatial light modulator 403 and the first lens 441a is the first focal length of the first lens 441a, the optical path distance between the focusing optical system 404 and the second lens 441b is the second focal length of the second lens 441b, and the optical path distance between the first lens 441a and the second lens 441b is the sum of the first focal length and the second focal length, forming a double-telecentric optical system. This 4f optical system 441 can prevent the wavefront shape of the laser light L modulated by the reflective spatial light modulator 403 from changing and increasing aberration as it propagates through space.

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

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

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

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

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

The laser processing apparatus 500 may also include, within the housing 431, a surface observation unit 411 for observing the laser light incident surface of the object, and an AF (AutoFocus) unit 412 for fine-tuning the distance between the focusing optical system 404 and the object. The surface observation unit 411 has an observation light source 411a and a detector 411b.

The laser processing apparatus 500 further includes a control unit 450, which is composed of a CPU, ROM, RAM, etc., for controlling the laser processing apparatus 500. This control unit 450 controls the laser light source 402 and adjusts the output and pulse width of the laser light L emitted from the laser light source 402. The control unit 450 also controls the position of the housing 431 and stage (not shown), and the drive of the drive unit 432.

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

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

Figure 22 is a diagram explaining the output derivation of each laser beam after splitting using the power meter 700. Figure 22(a) shows the split light from the reflective spatial light modulator 403 to the power meter 700. Figure 22(b) shows the position of the light shielding plate 420 provided in the Fourier plane (i.e., the plane including the confocal point O).

As shown in Figure 22(a), laser light that passes through the first branching pattern displayed on the liquid crystal layer of the reflective spatial light modulator 403 is branched into multiple beams (three in this case) by the first branching pattern. After branching, each laser beam passes through the first lens 441a and reaches the Fourier plane (the plane including the confocal point O). A light-shielding plate 420 is provided at the Fourier plane. The laser light that diverges through the confocal point O then passes through the second lens 441b and is focused by the focusing optical system 404 onto the power meter 700, which then measures the output (output measurement process when the light is blocked).

In the light-shielded output measurement process, the position of the light-shielded plate 420 provided on the Fourier plane is continuously changed. For example, as shown in FIG. 22(b), in the first step (STEP 1) of the light-shielded output measurement process, the light-shielded plate 420 is positioned so that it does not block any of the split laser beams (-1st order, 0th order, 1st order). In this case, the power meter 700 measures output data P1, which includes the output of all laser beams (-1st order, 0th order, 1st order). In the next step (STEP 2), the light-shielded plate 420 is positioned so that it blocks only the 1st order laser beam of the split laser beams (-1st order, 0th order, 1st order). In this case, the power meter 700 measures output data P2, which includes the output of two laser beams (-1st order, 0th order). In the final step (STEP 3), a light blocking plate 420 is placed at a position where the 0th and 1st order laser beams of the split laser beams (-1st order, 0th order, 1st order) are blocked. In this case, the power meter 700 measures output data P3, which includes the output of one laser beam (-1st order).

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

According to this laser processing method, a laser beam is emitted with a first branching pattern set in the reflective spatial light modulator 403 according to the output target value of each branched laser beam. The laser beam branched by the first branching pattern is measured by the power meter 700, and the actual output value of each branched laser beam is derived based on the measurement results. This laser processing method then generates and outputs balance parameters related to the generation of a second branching pattern that brings the actual output value closer to the output target value. This configuration generates balance parameters for generating a second branching pattern that brings the actual output value measured by the power meter 700 closer to the output target value. By generating balance parameters that bring the actually measured output closer to the target value, the calculation algorithm is corrected during the processing process using the balance parameters, and a second branching pattern is generated that brings the output of the branched beam closer to the output target value than the first branching parameter. This allows the output of the branched beam to be appropriately adjusted to the desired value. As described above, this laser processing method allows the output of the branched beam to be adjusted to the desired value, improving processing quality.

In addition, in the second step, a light-shielding output measurement process is performed in which the power meter 700 measures the output while a portion of each branched laser beam is shielded by the light shielding plate 420. In this light-shielding output measurement process, the power meter 700 measures the output while changing the range of laser beams shielded by the light shielding plate 420. In this way, by measuring the output with the power meter 700 while changing the range of laser beams shielded by the light shielding plate 420, the output of each branched laser beam can be appropriately derived.

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

Claims (7)

A laser processing device that forms a modified region in an object by irradiating the object with laser light,
a light source that emits the laser light;
a spatial light modulator that modulates the laser light emitted from the light source;
a detection unit that detects reflected light of the laser light from the object;
a control unit,
The control unit
a first process of generating a branching pattern for branching the laser beam into a plurality of beams, the first branching pattern corresponding to an output target value of each of the branched laser beams, based on a predetermined calculation algorithm, and setting the generated first branching pattern on the spatial light modulator to display it;
a second process of controlling the light source so that the laser light is emitted in a state in which the first branch pattern is displayed on the spatial light modulator;
a third process of controlling the detection unit so that the reflected light of each laser beam after branching according to the first branching pattern is detected;
a fourth process of deriving an actual output measurement value of each of the branched laser beams based on the detection result by the detection unit, and generating a correction parameter for correcting the calculation algorithm, the correction parameter being related to generation of a second branch pattern that is a branch pattern that brings the actual output value closer to the output target value;
a fifth process of correcting the calculation algorithm using the correction parameters, generating the second branch pattern based on the corrected calculation algorithm, and setting and displaying the generated second branch pattern on the spatial light modulator for a processing process. The control unit
In the first processing, a plurality of types of the first branching patterns are generated, each of which has a different combination of output target values of each of the branched laser beams;
The laser processing device according to claim 1 , wherein the fourth process generates the correction parameter common to at least two of the first branch patterns included in the plurality of types of first branch patterns. The control unit
3. The laser processing device according to claim 2, wherein in the fourth process, the plurality of types of first branch patterns are grouped according to similarity of branch parameters, and the common correction parameters are generated for each group. The control unit
4. The laser processing device according to claim 3, wherein in the fourth process, the grouping is performed according to the degree of approximation of the output target value, which is the branching parameter. The control unit
5. The laser processing device according to claim 3, wherein in the fifth process, information indicating a branching parameter in the processing process is acquired, and the calculation algorithm is corrected using the correction parameter of the group corresponding to the branching parameter. The control unit
6. The laser processing device according to claim 1, wherein in the first process, the first branching pattern is generated to branch the laser light to different positions in a vertical direction, which is a thickness direction of the object. A laser processing method for forming a modified region in an object by irradiating the object with laser light, comprising:
a first step of generating a branching pattern for branching a laser beam into a plurality of beams based on a predetermined calculation algorithm, the first branching pattern corresponding to an output target value of each of the branched laser beams, and setting the generated first branching pattern on a spatial light modulator to display it;
a second step of emitting laser light to the spatial light modulator on which the first branching pattern is displayed, and irradiating the target with the laser light branched into a plurality of beams by the first branching pattern;
a third step of detecting reflected light from the target of each of the split laser beams;
a fourth step of deriving an actual output measurement value of each of the split laser beams based on the detection result of the reflected light, and generating a correction parameter for correcting the calculation algorithm, the correction parameter being related to generation of a second branching pattern that is a branching pattern that brings the actual output value closer to the output target value;
a fifth step of correcting the calculation algorithm using the correction parameters, generating the second branch pattern based on the corrected calculation algorithm, and setting and displaying the generated second branch pattern on the spatial light modulator for a processing process .