Laser processing method, and laser processing system

Abstract

To provide a laser processing method, and a laser processing system.SOLUTION: A laser processing method is to irradiate a plurality of processing regions which is separated from each other on the surface of a workpiece with a pulse laser beam and form a plurality of recesses. The laser processing method includes: a first step of irradiating different processing regions for each pulse with the pulse laser beam; and a second step of irradiating the different processing regions for each of the pulses with the pulse laser beam so as to overlap a part of an irradiation region of the pulse laser beam in the first step.SELECTED DRAWING: Figure 9

Description

Technical Field

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

Background Art

[0002] In recent years, in semiconductor exposure apparatuses, as semiconductor integrated circuits have been miniaturized and highly integrated, an improvement in resolution has been demanded. For this reason, the wavelength of light emitted from an exposure light source has been shortened. For example, as a gas laser device for exposure, a KrF excimer laser device that outputs laser light with a wavelength of about 246.0 nm and an ArF excimer laser device that outputs laser light with a wavelength of about 193.4 nm are used.

[0003] The spectral linewidth of the spontaneous emission light of a KrF excimer laser device and an ArF excimer laser device is as wide as 350 pm to 400 pm. Therefore, when a projection lens is configured with a material that transmits ultraviolet light such as KrF and ArF laser light, chromatic aberration may occur. As a result, the resolution may decrease. Therefore, it is necessary to narrow the spectral linewidth of the laser light output from the gas laser device to such an extent that chromatic aberration can be ignored. For this reason, a narrowbanding module (Line Narrowing Module: LNM) including a narrowbanding element (etalon, grating, etc.) may be provided in the laser resonator of the gas laser device in order to narrow the spectral linewidth. Hereinafter, a gas laser device whose spectral linewidth is narrowed is referred to as a narrowbanding gas laser device.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

[0005] A laser processing method according to an aspect of the present disclosure is a laser processing method for irradiating a plurality of mutually separated processing regions on the surface of a workpiece with pulsed laser light to form a plurality of recesses, the method comprising: a first step of irradiating the pulsed laser light to different processing regions for each pulse; and a second step of irradiating the pulsed laser light to different processing regions for each pulse so as to overlap a part of the irradiation region of the pulsed laser light in the first step.

[0006] A laser processing system according to an aspect of the present disclosure is a laser processing system for irradiating a plurality of mutually separated processing regions on the surface of a workpiece with pulsed laser light to form a plurality of recesses, the system comprising: a gas laser device that emits pulsed laser light; a moving unit that can move the irradiation region on the surface of the pulsed laser light; and a processor, wherein the processor controls the moving unit and the gas laser device to perform a first control of irradiating the pulsed laser light to different processing regions for each pulse, and a second control of irradiating the pulsed laser light to different processing regions for each pulse so as to overlap a part of the irradiation region of the pulsed laser light in the first control.

Brief Description of the Drawings

[0007] Some embodiments of the present disclosure will be described below by way of example only with reference to the accompanying drawings.

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[0008] 1. Description of the Laser Processing System and Laser Processing Method of the Comparative Example 1.1 Configuration 1.2 Operation 1.3 Problems 2. Description of the Laser Processing System and Laser Processing Method of Embodiment 1 2.1 Configuration 2.2 Operation 2.3 Effects 2.4 Description of the Laser Processing Method of Modification Example 1 of Embodiment 1 2.5 Description of the Laser Processing Method of Modification Example 2 of Embodiment 1 3. Description of the Laser Processing System and Laser Processing Method of Embodiment 2 3.1 Configuration 3.2 Operation 3.3 Effects

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The embodiments described below show some examples of the present disclosure and do not limit the content of the present disclosure. Also, not all of the configurations and operations described in each embodiment are essential as the configurations and operations of the present disclosure. The same reference numerals are assigned to the same components, and duplicate descriptions are omitted.

[0010] 1. Description of the Laser Processing System and Laser Processing Method of the Comparative Example 1.1 Configuration The laser processing system and laser processing method of the comparative example will be described. Note that the comparative example of the present disclosure is a form that the applicant recognizes as being known only to the applicant and is not a known example recognized by the applicant.

[0011] FIG. 1 is a schematic diagram showing an overall schematic configuration example of the laser processing system 10 of this example. The laser processing system 10 of this example mainly includes a gas laser device 100, a laser processing device 300, and an optical path tube PO that connects the gas laser device 100 and the laser processing device 300. Hereinafter, the direction parallel to the optical axis direction of the laser light incident on the workpiece 20 will be described as the Z direction, the first direction orthogonal to the Z direction will be described as the X direction, and the second direction orthogonal to the X direction and the Z direction will be described as the Y direction. The Z direction is also the height direction of the workpiece 20.

[0012] The gas laser device 100 in this example is an ArF excimer laser device that uses a mixed gas containing argon (Ar), fluorine (F2), and neon (Ne). The gas laser device 100 outputs laser light with a central wavelength of approximately 193.4 nm. Note that the gas laser device 100 may be a gas laser device other than an ArF excimer laser device. For example, it may be a KrF excimer laser device that uses a mixed gas containing krypton (Kr), F2, and Ne. In this case, the gas laser device 100 emits laser light with a central wavelength of approximately 246.0 nm. The mixed gas containing Ar, F2, and Ne as the laser medium or the mixed gas containing Kr, F2, and Ne as the laser medium may be referred to as laser gas.

[0013] The gas laser device 100 mainly includes a housing 110, a laser oscillator 130, a monitor module 150, a shutter 170, and a laser processor 190 disposed in the internal space of the housing 110.

[0014] The laser oscillator 130 includes a laser chamber 131, a charger 141, a pulse power module 143, a rear mirror 145, and an output coupling mirror 147. In FIG. 1, the internal configuration of the laser chamber 131 is shown as viewed from a direction substantially perpendicular to the traveling direction of the laser light.

[0015] The laser chamber 131 includes an internal space where light is generated by excitation of the laser medium in the above-mentioned laser gas. The light travels to the windows 139a and 139b, which will be described later. The laser gas is supplied from a laser gas supply source (not shown) to the internal space of the laser chamber 131 through a pipe (not shown). Further, the laser gas in the laser chamber 131 is subjected to a process of removing F2 gas by a halogen filter or the like, and is exhausted to the housing 110 through a pipe (not shown) by an exhaust pump (not shown).

[0016] In the internal space of the laser chamber 131, a pair of electrodes 133a and 133b face each other, and their longitudinal directions are arranged along the light traveling direction. The electrodes 133a and 133b are discharge electrodes for exciting the laser medium by glow discharge. In this example, the electrode 133a is the cathode and the electrode 133b is the anode.

[0017] The electrode 133a is supported by the electrical insulation part 135. The electrical insulation part 135 closes an opening formed in the laser chamber 131. A conductive part (not shown) is embedded in the electrical insulation part 135, and the conductive part applies a high voltage supplied from the pulse power module 143 to the electrode 133a. The electrode 133b is supported by the return plate 137, and the return plate 137 is connected to the inner surface of the laser chamber 131 by wiring (not shown).

[0018] The charger 141 is a DC power supply device that charges a charging capacitor (not shown) in the pulse power module 143 with a predetermined voltage. The pulse power module 143 includes a switch 143a controlled by the laser processor 190. When the switch 143a changes from OFF to ON, the pulse power module 143 generates a pulsed high voltage from the electrical energy held in the charger 141 and applies this high voltage between the electrode 133a and the electrode 133b.

[0019] When a high voltage is applied between the electrode 133a and the electrode 133b, a discharge occurs between the electrode 133a and the electrode 133b. The energy of this discharge excites the laser medium in the laser chamber 131, and the excited laser medium emits light when transitioning to the ground state.

[0020] The laser chamber 131 is provided with windows 139a and 139b. Window 139a is located on one end side in the traveling direction of the laser beam in the laser chamber 131, window 139b is located on the other end side in the traveling direction, and windows 139a and 139b sandwich the space between the electrodes 133a and 133b. Windows 139a and 139b are inclined at a Brewster angle with respect to the traveling direction of the laser beam so that the reflection of the P-polarized light of the laser beam is suppressed. The laser beam oscillated as described later is emitted to the outside of the laser chamber 131 through windows 139a and 139b. Since a pulsed high voltage is applied between the electrodes 133a and 133b by the pulse power module 143 as described above, this laser beam is a pulsed laser beam.

[0021] The rear mirror 145 is disposed in the internal space of a housing 145a connected to one end side of the laser chamber 131, and reflects the laser beam emitted from the window 139a and returns it to the laser chamber 131. The output coupling mirror 147 is disposed in the internal space of an optical path tube 147a connected to the other end side of the laser chamber 131, transmits a part of the laser beam emitted from the window 139b, and reflects the other part of the laser beam back to the internal space of the laser chamber 131. In this way, the rear mirror 145 and the output coupling mirror 147 constitute a Fabry - Perot type laser resonator, and the laser chamber 131 is disposed on the optical path of the laser resonator.

[0022] The monitor module 150 is disposed on the optical path of the laser beam emitted from the output coupling mirror 147. The monitor module 150 includes, for example, a housing 151, a beam splitter 153 and an optical sensor 155 disposed in the internal space of the housing 151. An opening is formed in the housing 151, and through this opening, the internal space of the housing 151 communicates with the internal space of the optical path tube 147a.

[0023] The beam splitter 153 transmits a part of the laser light emitted from the output coupling mirror 147 toward the shutter 170, and reflects the other part of the laser light toward the light receiving surface of the photosensor 155. The photosensor 155 measures the energy E of the laser light incident on the light receiving surface. The photosensor 155 outputs a signal indicating the measured energy E to the laser processor 190.

[0024] The laser processor 190 of the present disclosure is a processing device including a storage device 190a storing a control program and a CPU (Central Processing Unit) 190b executing the control program. The laser processor 190 is specially configured or programmed to execute various processes included in the present disclosure. Further, the laser processor 190 controls the entire gas laser device 100.

[0025] The laser processor 190 transmits and receives various signals to and from the laser processing processor 310 of the laser processing apparatus 300. For example, the laser processor 190 receives from the laser processing processor 310 signals indicating a light emission trigger Tr and a target energy Et, which will be described later. The laser processor 190 controls the charging voltage of the charger 141 based on the energy E and the target energy Et received from the photosensor 155 and the laser processing processor 310. By controlling this charging voltage, the energy of the laser light is controlled. Further, the laser processor 190 transmits an ON or OFF command signal for the switch 143a to the pulse power module 143. Further, the laser processor 190 is electrically connected to the shutter 170 and controls the opening and closing of the shutter 170.

[0026] The laser processor 190 closes the shutter 170 until the difference ΔE between the energy E received from the monitor module 150 and the target energy Et received from the laser processing processor 310 is within the allowable range. When the difference ΔE is within the allowable range, the laser processor 190 transmits a reception preparation completion signal indicating that the reception preparation of the emission trigger Tr is completed to the laser processing processor 310. When receiving the reception preparation completion signal, the laser processing processor 310 transmits a signal indicating the emission trigger Tr to the laser processor 190, and the laser processor 190 opens the shutter 170 upon receiving the signal indicating the emission trigger Tr. The emission trigger Tr is defined by a predetermined repetition frequency f and a predetermined number of pulses P of the laser beam, and is a timing signal for the laser processing processor 310 to cause the laser oscillator 130 to oscillate the laser, and is an external trigger. The repetition frequency f of the laser beam is, for example, 1 kHz or more and 10 kHz or less.

[0027] The shutter 170 is disposed in the optical path of the laser beam that has passed through an opening formed on the side opposite to the side to which the optical path tube 147a in the housing 151 is connected through the beam splitter 153 of the monitor module 150. Further, the shutter 170 is disposed in the internal space of the optical path tube 171, and the optical path tube 171 is connected to the housing 151 so as to surround the opening and communicates with the housing 151. Further, the optical path tube 171 communicates with the laser processing apparatus 300 through the opening of the housing 110 and the optical path tube PO.

[0028] The internal spaces of the optical path tube 171 and the optical path tube 147a, and the internal spaces of the housing 151 and the housing 145a are filled with a purge gas. The purge gas includes an inert gas such as nitrogen (N2). The purge gas is supplied from a purge gas supply source (not shown) through a pipe (not shown) to the internal spaces of the optical path tube 171 and the optical path tube 147a, and the internal spaces of the housing 151 and the housing 145a.

[0029] The laser processing apparatus 300 mainly includes a laser processing processor 310, an optical system 330, a stage 350, a housing 355, and a frame 357. The optical system 330 and the stage 350 are arranged in the internal space of the housing 355. The housing 355 is fixed to the frame 357. An optical path tube PO is connected to the housing 355, and the internal space of the housing 355 communicates with the internal space of the optical path tube PO through an opening formed in the housing 355, and the laser light that has passed through the shutter 170 enters the housing 355.

[0030] The laser processing processor 310 is a processing device that includes a storage device 310a in which a control program is stored and a CPU 310b that executes the control program. The laser processing processor 310 is specially configured or programmed to execute various processes included in the present disclosure. The laser processing processor 310 controls the entire laser processing apparatus 300.

[0031] The optical system 330 includes high-reflection mirrors 331a, 331b, 331c, an attenuator 332, a fly-eye lens 333, a condenser lens 334, a mask 335, and a projection optical system 336. Each component of the optical system 330 is fixed to a holder (not shown) and is arranged at a predetermined position in the housing 355.

[0032] The high-reflection mirrors 331a, 331b, 331c are formed by coating a reflective film that highly reflects laser light on the surface of a transparent substrate made of, for example, synthetic quartz or calcium fluoride. The high-reflection mirror 331a reflects the laser light incident from the gas laser device 100 toward the attenuator 332. The high-reflection mirror 331b reflects the laser light from the attenuator 332 toward the high-reflection mirror 331c. The high-reflection mirror 331c reflects the laser light from the high-reflection mirror 331b toward the fly-eye lens 333.

[0033] The attenuator 332 is disposed on the optical path between the high-reflection mirror 331a and the high-reflection mirror 331b. The attenuator 332 includes, for example, rotary stages 332a, 332b and partial reflection mirrors 332c, 332d fixed to the rotary stages 332a, 332b. Each of the rotary stages 332a, 332b is electrically connected to the laser processing processor 310 and rotates around the Y-axis by a control signal from the laser processing processor 310. When the rotary stages 332a, 332b rotate respectively, the partial reflection mirrors 332c, 332d also rotate respectively. The partial reflection mirrors 332c, 332d are optical elements whose transmittance changes depending on the incident angle of the laser beam Lb to the partial reflection mirrors 332c, 332d. The rotation angle of the partial reflection mirrors 332c, 332d around the Y-axis is adjusted by the rotation of the rotary stages 332a, 332b so that the incident angles of the laser beams coincide with each other and the transmittance of the partial reflection mirrors 332c, 332d becomes the desired transmittance. Thereby, the laser beam from the high-reflection mirror 331a is attenuated to the desired energy and passes through the attenuator 332.

[0034] The fly-eye lens 333 is a lens in which a plurality of lenses are arranged in parallel, for example, in a honeycomb shape, and is also called an integrator lens. The fly-eye lens 333 is arranged so that the focal plane on the exit side of the fly-eye lens 333 coincides with the focal plane on the incident surface side of the condenser lens 334, and emits light so that the energy density of the laser beam incident on the condenser lens 334 becomes uniform.

[0035] The condenser lens 334 is a lens that condenses the laser beam emitted from the fly-eye lens 333, and is arranged so that the focal plane on the exit side of the condenser lens 334 is on the mask 335.

[0036] The mask 335 is, for example, a plate-like member in which a transmission hole through which a part of the laser beam passes is formed and the other part of the laser beam is blocked. In this example, the transmission hole is formed of a rectangular hole, and when the laser beam passes through the transmission hole, the outer shape of the laser beam becomes a rectangular shape elongated in the Y direction.

[0037] The projection optical system 336 includes, for example, a collimator lens 336a and a condenser lens 336b. The collimator lens 336a emits the laser light from the mask 335 as parallel light. The condenser lens 336b condenses the laser light from the collimator lens 336a onto the surface of the workpiece 20.

[0038] The stage 350 is disposed on the bottom surface of the housing 355 and includes a table 351. Also, the stage 350 can move the table 351 in the X direction, Y direction, and Z direction according to a control signal from the laser processing processor 310, and can adjust the position of the table 351 by this movement.

[0039] The table 351 supports the workpiece 20. The main surface of the table 351 is substantially orthogonal to the Z axis and substantially along the XY plane. Therefore, the front and back surfaces of the workpiece 20 are substantially orthogonal to the Z axis and are located substantially along the XY plane. With the above configuration, the stage 350 can move the workpiece 20 via the table 351 so that a plurality of laser lights emitted from the optical system 330 irradiate a desired position of the workpiece 20, and can adjust the position of the workpiece 20. That is, the stage 350 is a moving part that can move the irradiation region on the surface of the workpiece 20 of the laser light in the X direction and Y direction perpendicular to the irradiation direction of the laser light.

[0040] The workpiece 20 is an object on which laser processing is performed by irradiation with laser light. Examples of the workpiece 20 include a light-transmissive plate-like member that becomes an optical waveguide substrate. Examples of the material constituting this plate-like member include polyimide resin and polynorbornene resin.

[0041] During the operation of the laser processing system 10, an inert gas constantly flows through the internal space of the housing 355. This inert gas is, for example, nitrogen gas. The housing 355 is provided with an intake port (not shown) for inhaling the inert gas into the housing 355 and an exhaust port (not shown) for discharging the inert gas from the housing 355 to the outside. An intake pipe and an exhaust pipe (not shown) are connected to the intake port and the exhaust port, respectively. A gas supply source (not shown) for supplying the inert gas is connected to the intake port through a pipe. The inert gas supplied from the intake port also flows into the optical path pipe PO communicating with the housing 355.

[0042] 1.2 Operation Next, the operation of the laser processing system 10 of the comparative example and the laser processing method will be described.

[0043] In the gas laser device 100, before the gas laser device 100 emits a laser beam, the internal spaces of the optical path pipes 147a, 171, PO and the internal spaces of the housings 145a, 151 are filled with a purge gas from a purge gas supply source (not shown). Also, a laser gas is supplied from a laser gas supply source (not shown) to the internal space of the laser chamber 131. Further, in the laser processing device 300, an inert gas such as nitrogen gas flows through the internal space of the housing 355.

[0044] In the laser processing device 300, the workpiece 20 is supported on the table 351. The laser processing processor 310 sets the coordinates X, Y, and Z of the initial irradiation position for irradiating a laser beam to form the processed part on the stage 350. Thereby, the stage 350 moves the table 351 together with the workpiece 20 to the set initial irradiation position. Note that the irradiation position is the position of the center of the irradiation region where the laser beam is irradiated.

[0045] After the table 351 moves, the laser processing processor 310 controls the transmittance of the attenuator 332 of the optical system 330 and the gas laser device 100 so that the laser light irradiated on the workpiece 20 has a desired fluence F required for laser processing. The fluence F is defined as a value obtained by dividing the energy of the laser light by the cross-sectional area of the laser light perpendicular to the optical axis of the laser light.

[0046] The laser processor 190 closes the shutter 170 and drives the charger 141. Also, the laser processor 190 turns on the switch 143a of the pulse power module 143. As a result, the pulse power module 143 applies a pulsed high voltage between the electrode 133a and the electrode 133b from the electrical energy held in the charger 141. Due to this high voltage, a discharge occurs between the electrode 133a and the electrode 133b, and the laser medium contained in the laser gas between the electrode 133a and the electrode 133b is excited, and light is emitted when the laser medium returns to the ground state. Due to this light, light resonates between the rear mirror 145 and the output coupling mirror 147, and the light is amplified each time it passes through the discharge space in the internal space of the laser chamber 131, and laser oscillation occurs. Then, a part of the laser light passes through the output coupling mirror 147 as pulsed laser light and travels to the beam splitter 153.

[0047] A part of the laser light that has traveled to the beam splitter 153 is reflected by the beam splitter 153 and received by the optical sensor 155. The optical sensor 155 measures the energy E of the received laser light and outputs a signal indicating the energy E to the laser processor 190. The laser processor 190 controls the charging voltage so that the difference ΔE between the energy E and the target energy Et is within an allowable range, and after the difference ΔE is within the allowable range, it transmits a reception preparation completion signal indicating that the reception preparation of the emission trigger Tr has been completed to the laser processing processor 310.

[0048] When the laser processing processor 310 receives the reception ready completion signal, it transmits the emission trigger Tr to the laser processor 190. When the laser processor 190 opens the shutter 170 in synchronization with the reception of the emission trigger Tr, the laser light that has passed through the shutter 170 enters the laser processing apparatus 300. This laser light is, for example, pulsed laser light with a center wavelength of 193.4 nm.

[0049] The laser light that has entered the laser processing apparatus 300 is irradiated onto the mask 335 via the high reflection mirror 331a, the attenuator 332, the high reflection mirrors 331b and 331c, the fly-eye lens 333, and the condenser lens 334. At this time, the laser light is Koehler illuminated on the mask 335. In the mask 335, among the laser light, a part of the laser light passes through the through holes and becomes laser light having a rectangular shape elongated in the Y direction, and the other part of the laser light is blocked. The laser light that has passed through the mask 335 is made parallel by the collimator lens 336a of the projection optical system 336 and is focused on the surface of the workpiece 20 by the condenser lens 336b.

[0050] The laser light is irradiated onto the workpiece 20 according to the emission trigger Tr defined by the repetition frequency f and the number of pulses P required for laser processing. Near the surface of the workpiece 20, ablation occurs due to the irradiation of the laser light, and defects are generated. As a result, the processed part is processed on the workpiece 20, and a dent is formed. In this example, a plurality of processed parts separated from each other are processed, and a plurality of dents are formed.

[0051] FIG. 2 is a diagram for explaining the machining sequence on the surface of the workpiece 20. The machining area 21 shown in FIG. 2 is an area where laser light is irradiated for machining. In this example, a plurality of machining areas 21 are arranged side by side in the Y direction with a gap therebetween. The outer shape of the machining area 21 is generally rectangular, including opposite sides facing each other in the X direction and opposite sides facing each other in the Y direction. The width of the machining area 21 in the Y direction is approximately the same as the width of the irradiation area 22 where the laser light is irradiated in one pulse, and the width of the machining area 21 in the X direction is wider than the width of the irradiation area 22 in the X direction and is approximately twice that width. Therefore, by irradiating the laser light a plurality of times, the entire machining area 21 is irradiated with the laser light. In FIG. 2, in order to distinguish the machining area 21 and the irradiation area 22, the irradiation area 22 is hatched with a plurality of dots. Also, the description of some of the machining areas 21 is omitted.

[0052] FIG. 3 is a diagram showing an example of the irradiation area 22 in the first irradiation to the machining area 21, and FIG. 4 is a cross-sectional view showing the state of the workpiece 20 after the first irradiation to the machining area 21. As shown in FIG. 3, in this example, first, the workpiece 20 is moved by the stage 350 so that the irradiation area 22 is along one edge of the machining area 21 in the X direction, and the surface of the workpiece 20 is irradiated with laser light. For this reason, the laser light is irradiated to the irradiation area 22, and as shown in FIG. 4, a recess 25 is formed in the workpiece 20.

[0053] FIG. 5 is a diagram showing an example of the irradiation region 22 in the second irradiation with respect to the processing region 21, and FIG. 6 is a cross-sectional view showing the state of the workpiece 20 after the second irradiation with respect to the processing region 21. After the first irradiation with respect to the processing region 21, as shown in FIG. 5, the workpiece 20 is moved to one side in the X direction by the stage 350, and the surface of the workpiece 20 is irradiated with laser light. The irradiation region 22a of the laser light irradiated at this time overlaps a part of the irradiation region 22 of the laser light irradiated immediately before, and the center 23a of the irradiation region 22a is located on the other side in the X direction from the center 23 of the irradiation region 22. This irradiation region 22a is a region where the irradiation region 22a where the irradiation region 22 overlaps moves in the short side direction of the outer shape of the laser light. Also, the direction from the center 23a of the irradiation region 22a toward the center 23 of the irradiation region 22 where the irradiation region 22a overlaps is the X direction, and the width of the processing region 21 in the X direction is twice the width in the short side direction of the laser light. In FIG. 5, in order to distinguish the irradiation region 22 and the irradiation region 22a, the irradiation region 22 is provided with hatching consisting of a plurality of dots, and the irradiation region 22a is provided with hatching consisting of a plurality of slashes.

[0054] By irradiating the irradiation region 22a with laser light, as shown in FIG. 6, another recess 25 is formed in the workpiece 20. Since the irradiation region 22a overlaps a part of the irradiation region 22 of the laser light irradiated immediately before, a part of the edge of the irradiation region 22 is located within the irradiation region 22a. Corners are more easily processed by laser light than planar parts. For this reason, the corners along the edge of the irradiation region 22 located within the irradiation region 22a are more easily processed than other parts and have a chamfered shape.

[0055] FIG. 7 is a cross-sectional view showing the state of the workpiece 20 after the entire processing area 21 is irradiated with laser light. The movement of the laser light irradiation area 22 and the irradiation of the laser light are repeated until the laser light irradiation area 22 reaches the edge on the other side of the processing area 21 in the X direction, and the entire processing area 21 is irradiated with laser light. In this way, the recess 30 shown in FIG. 7 is formed by forming a plurality of recesses 25. As described above, the corners are more easily processed by the laser light than the planar portions, and the laser light is irradiated multiple times on the portion on the other side in the X direction at the edge of the recess 25. For this reason, the portion on the other side in the X direction of the edge of the recess 30 becomes a generally flat inclined surface 31, and the portion on one side in the X direction of the edge of the recess 30 becomes stepped. The inclined surface 31 is the surface on which the reflective film serving as the micromirror of the optical waveguide substrate is provided. In this example, the recess 30 is not a through hole penetrating to the back surface of the workpiece 20, but it may be a through hole.

[0056] Next, the workpiece 20 is moved by the stage 350 so that the irradiation area 22 is along the edge on one side in the X direction of another processing area 21, and the above-described irradiation of the laser light and the movement of the irradiation area 22 are repeated. In this example, the processing areas 21 irradiated with laser light are changed in order from one side in the Y direction. In this way, a plurality of recesses 30 are formed in the workpiece 20.

[0057] 1.3 Problems In the processing by the laser processing apparatus 300 of the comparative example, since the laser light is repeatedly irradiated so as to overlap a part of the immediately preceding irradiation area 22, the workpiece 20 may be overheated and the workpiece 20 may be deformed by the heat.

[0058] Therefore, in the following embodiments, the laser processing system 10 and the laser processing method capable of suppressing the deformation of the workpiece 20 due to heat are exemplified.

[0059] 2. Description of the Laser Processing System and the Laser Processing Method of Embodiment 1 The laser processing system 10 and the laser processing method according to Embodiment 1 will be described. Note that the same components as those described above are denoted by the same reference numerals, and redundant descriptions are omitted unless otherwise specified.

[0060] 2.1 Configuration FIG. 8 is a schematic diagram showing a schematic configuration example of the laser processing apparatus 300 according to the present embodiment. As shown in FIG. 8, in the laser processing apparatus 300 according to the present embodiment, the arrangements of the fly-eye lens 333, the condenser lens 334, and the mask 335 are different from those in the laser processing apparatus 300 of the comparative example. Further, the laser processing apparatus 300 according to the present embodiment includes galvano scanners 361 and 362 instead of the high-reflection mirror 331c, and includes an fθ lens 370 instead of the projection optical system 336.

[0061] The fly-eye lens 333, the condenser lens 334, and the mask 335 are arranged on the optical path between the attenuator 332 and the high-reflection mirror 331b.

[0062] The galvano scanner 361 includes a drive unit 361a and a mirror 361b attached to the swing axis of the drive unit 361a and swingable around the swing axis. The configuration of the galvano scanner 362 is the same as that of the galvano scanner 361, and the galvano scanner 362 includes a drive unit 362a and a mirror 362b attached to the swing axis of the drive unit 362a and swingable around the swing axis.

[0063] The drive units 361a and 362a are motors or the like and are electrically connected to the laser processing processor 310. The swing speed and swing angle of the swing axes of the drive units 361a and 362a are controlled by control signals from the laser processing processor 310. The swing axis of the drive unit 361a is orthogonal to the swing axis of the drive unit 362a.

[0064] Mirror 361b reflects the laser light from high-reflection mirror 331b toward mirror 362b, and mirror 362b reflects the laser light from mirror 361b toward fθ lens 370. The orientations of mirrors 361b and 362b are adjusted by the swing angles of the respective swing axes of drive units 361a and 362a. The adjustments of the orientations of mirrors 361b and 362b may be synchronized. The speeds of mirrors 361b and 362b during swinging are adjusted by the swing speeds when the swing axes of drive units 361a and 362a swing.

[0065] Galvanometer scanner 361 can change the optical path of the laser light along the X direction by mirror 361b and move the irradiation area 22 of the laser light in the X direction. Galvanometer scanner 362 can change the optical path of the laser light along the Y direction by mirror 362b and move the irradiation area 22 of the laser light in the Y direction. That is, galvanometer scanner 361 is a first moving part that can move the irradiation area 22 of the laser light in the X direction perpendicular to the irradiation direction of the laser light. Also, galvanometer scanner 362 is a second moving part that can move the irradiation area 22 of the laser light in the Y direction perpendicular to the irradiation direction of the laser light. The minimum moving distance of the irradiation area 22 that galvanometer scanner 361 can adjust is approximately the same as the minimum moving distance of the irradiation area 22 that galvanometer scanner 362 can adjust.

[0066] fθ lens 370 is fixed to a holder (not shown) on the optical path between mirror 362b and workpiece 20 and is arranged at a predetermined position within housing 355. The optical axis of fθ lens 370 is along the Z direction. fθ lens 370 focuses the laser light irradiated from galvanometer scanner 362 onto the surface of workpiece 20 along the optical axis of fθ lens 370.

[0067] 2.2 Operation Next, the operation of laser processing processor 310 in this embodiment will be described.

[0068] FIG. 9 is a diagram showing a control flowchart of the laser processing processor 310 of the present embodiment. The control flowchart of the present embodiment includes steps SP11 to SP18, and shows a laser processing method for forming a plurality of recesses 30 in the workpiece 20. Further, FIG. 10 is a diagram for explaining the movement of the irradiation region 22 in the present embodiment.

[0069] In the starting state shown in FIG. 9, the laser processing processor 310 has received a reception ready signal from the laser processor 190, but has not transmitted the emission trigger Tr to the laser processor 190. Therefore, although the laser light is emitted from the laser oscillator 130, the shutter 170 is closed, so that the laser light does not enter the laser processing apparatus 300 from the gas laser apparatus 100. Also, in the starting state, the workpiece 20 is already supported on the table 351.

[0070] (Step SP11) This step is a preparation step before the laser processing apparatus 300 starts actual operation. In this step, the laser processing processor 310 reads parameters from the storage device 310a. The parameters of the present embodiment include the number nmax of processing regions 21, the maximum number mmax of times of irradiating laser light to each processing region 21, the number n, the irradiation number m, and the coordinates Xn,m of the irradiation position for irradiating the laser.

[0071] The machining areas 21 are numbered from 1 to nmax. The number n is the number of the machining area 21, and the initial value of n is 1. In the present embodiment, the numbers increase in order from the machining area 21 located at one end in the Y direction. The irradiation number m is a number indicating the number of times of laser beam irradiation for each machining area 21, and the initial value is 1. The coordinates Xn,m of the irradiation position are the XY coordinates of the irradiation position when the laser beam is irradiated for the m-th time in the machining area 21 with the number n, and are the XY coordinates of the center 23 of the irradiation area 22 at this time. And for each machining area 21, there are mmax coordinates Xn,m of the irradiation positions. In the present embodiment, the irradiation area 22 at the coordinate Xn,1 is along one edge in the X direction of the n-th machining area 21. The coordinate Xn,m moves from one side to the other side along the X direction as m increases. The moving distance of the coordinate Xn,m when m increases by only 1 is constant. And the irradiation area 22 at the coordinate Xn,mmax is along the other edge in the X direction of the n-th machining area 21. Also, the irradiation area 22 at the coordinate Xn,m+1 overlaps a part of the irradiation area 22 at the coordinate Xn,m.

[0072] (Step SP12) This step is a step of moving the irradiation position of the laser beam. In this step, the laser processing processor 310 controls the galvanoscanners 361, 362 so that the coordinates of the irradiation position become Xn,m. When the laser processing processor 310 controls the galvanoscanners 361, 362, it advances the control flow to step SP13.

[0073] (Step SP13) This step is to irradiate the workpiece 20 with laser light only once. In this step, the laser processing processor 310 sends the emission trigger Tr to the laser processor 190 to cause the shutter 170 to open in the laser processor 190. As a result, the laser light enters the laser processing apparatus 300 from the gas laser apparatus 100. The incident laser light travels in the order of the high reflection mirror 331a, the attenuator 332, the fly-eye lens 333, the condenser lens 334, the mask 335, the high reflection mirror 331b, the mirror 361b, the mirror 362b, and the fθ lens 370, and is irradiated onto the workpiece 20. When the workpiece 20 is processed by the irradiation of the laser light and the irradiation of the laser light is performed once, the laser processing processor 310 advances the control flow to step SP14. In this embodiment, the shutter 170 is maintained in the open state until the processing of the workpiece 20 is completed, and the steps performed until returning to this step are performed during the period until the laser light next enters the laser processing apparatus 300 from the gas laser apparatus 100.

[0074] (Step SP14) This step is to vary the next step according to the number n. In this step, when the number n is less than nmax, the laser processing processor 310 advances the control flow to step SP15, and when the number n is greater than or equal to nmax, the laser processing processor 310 advances the control flow to step SP16.

[0075] (Step SP15) This step is to increase the number n by 1. In this step, the laser processing processor 310 rewrites the number n to n + 1 and returns the control flow to step SP12. Therefore, as the first step, a process is performed to move the irradiation area 22 along the arrow a shown in FIG. 10 and irradiate each processing area 21 with laser light once in order from one side in the Y direction. Since the movement of the irradiation area 22 is a movement along the Y direction, in step SP12 when performing these irradiations, the laser processing processor 310 controls the galvanoscanners 361 and 362 so that the orientation of the mirror 361b of the galvanoscanner 361 changes and the orientation of the mirror 362b of the galvanoscanner 362 is maintained. Then, when all the processing areas 21 have been irradiated with laser light once, the control flow proceeds to step SP16.

[0076] (Step SP16) This step is to increase the irradiation number m by 1. In this step, the laser processing processor 310 rewrites the irradiation number m to m + 1 and advances the control flow to step SP17.

[0077] (Step SP17) This step is to vary the next step according to the irradiation number m. In this step, the laser processing processor 310 advances the control flow to step SP18 when the irradiation number m is less than or equal to mmax, and ends the control flow when the irradiation number m is greater than mmax.

[0078] (Step SP18) This step is to set the number n to 1. In this step, the laser processing processor 310 rewrites the number n to 1 and returns the control flow to step SP12. Therefore, when the laser light irradiates all the processing regions 21 once, the irradiation region 22 moves to the processing region 21 located at one end in the Y direction. Then, as the second step, a step of moving the irradiation region 22 along the arrow b shown in FIG. 10 and irradiating each processing region 21 with the laser light once in order from one side in the Y direction is performed. As described above, the irradiation region 22 at the coordinates Xn,m+1 overlaps a part of the irradiation region 22 at the coordinates Xn,m. Therefore, when the irradiation number m is 2 or more, the irradiation region 22 overlaps a part of the irradiation region 22 of the laser light when the irradiation number m is m-1. Therefore, the irradiation region 22 in the second step overlaps a part of the irradiation region 22 of the pulsed laser light in the first step. Also, the irradiation region 22 at the coordinates Xn,m+1 is a region where the irradiation region 22 at the coordinates Xn,m with which it overlaps has moved in the X direction, which is the short side direction of the outer shape of the laser light. Therefore, the irradiation region 22 in the second step is a region where the irradiation region 22 in the first step has moved in the short side direction of the outer shape of the pulsed laser light. That is, in the second step, the laser processing processor 310 controls the galvanometer scanner 361 to position the optical path of the pulsed laser light on the X direction side from the optical path in the first step. Then, until the irradiation number m becomes mmax or more, the movement of the irradiation region 22 and the irradiation of the laser light are repeated, and the recess 30 is formed for each processing region 21.

[0079] In the above control flowchart, when the control flow returns from step SP17 to step SP12 with the irradiation number m being the integer α, the pulsed laser light is irradiated onto different processing regions 21 for each pulse by repeating steps SP12, SP13, SP14, and SP15. Therefore, this repetition of steps SP12, SP13, SP14, and SP15 can be considered as the first step. In this first step, the laser processing processor 310 controls the galvanoscanners 361 and 362 as the moving parts to perform the first control of irradiating the pulsed laser light onto different processing regions 21 for each pulse. When the irradiation of the laser light onto the processing region 21 with the number nmax is completed, the irradiation number m becomes α + 1 in step SP16, and in this state, the control flow returns from step SP17 to step SP12. When the control flow is like this, the pulsed laser light is irradiated onto different regions for each pulse so as to overlap a part of the irradiation region 22 of the pulsed laser light in the first step by repeating steps SP12, SP13, SP14, and SP15. That is, the repetition of steps SP12, SP13, SP14, and SP15 when the control flow returns from step SP17 to step SP12 with the irradiation number m being α + 1 can be considered as the second step. In this second step, the laser processing processor 310 controls the galvanoscanners 361 and 362 as the moving parts to perform the second control of irradiating the pulsed laser light onto different processing regions 21 for each pulse so as to overlap a part of the irradiation region 22 of the pulsed laser light in the first control.

[0080] 2.3 Operation and Effect The laser processing method of this embodiment includes a first step of irradiating pulsed laser light to different processing regions 21 for each pulse, and a second step of irradiating pulsed laser light to different processing regions 21 for each pulse so as to overlap a part of the irradiation region 22 of the pulsed laser light in the first step. Further, in the laser processing system 10 of this embodiment, the laser processing processor 310 performs the above-described first control corresponding to the first step and the above-described second control corresponding to the second step. Therefore, according to the laser processing method and the laser processing system 10 of this embodiment, it is possible to suppress the pulsed laser light from being continuously irradiated to the same processing region 21. Accordingly, compared with the case where the pulsed laser light is continuously irradiated to the same processing region 21, it is possible to suppress the workpiece 20 from being overheated, and it is possible to suppress the deformation of the workpiece 20 due to heat. Further, the time interval for irradiating the pulsed laser light can be shortened, and the time required to form a plurality of recesses 30 in the workpiece 20 can be shortened.

[0081] Further, the laser processing system 10 of this embodiment includes a galvanometer scanner 361 capable of moving the irradiation region 22 of the laser light in the X direction, and a galvanometer scanner 361 capable of moving the irradiation region 22 in the Y direction perpendicular to the X direction. Further, the plurality of processing regions 21 are arranged along the Y direction. Then, the galvanometer scanner 361 moves the irradiation region 22 so that the irradiation region 22 is located within a processing region 21 different from the processing region 21 irradiated with the pulsed laser light in the immediately preceding pulse. The galvanometer scanner 361 can shorten the time required to move the irradiation region 22 compared with the stage 350 that moves the irradiation region 22 by moving the table 351 that supports the workpiece 20. Therefore, according to the laser processing system 10 of this embodiment, the processing time can be reduced compared with the case where the stage 350 moves the irradiation region 22 between different processing regions 21. Note that at least one of the movement of the irradiation region 22 in the X direction and the movement of the irradiation region 22 in the Y direction may be performed by the stage 350. For example, when the movement of the irradiation region 22 in the X direction is performed by the stage 350, in the second step, the laser processing processor 310 controls the stage 350 to position the workpiece 20 on the X direction side from the workpiece 20 in the first step.

[0082] In addition, in the laser processing method of the present embodiment, the plurality of processing regions 21 are arranged in the Y direction, and in the first step and the second step, pulsed laser light is irradiated onto the processing regions 21 in order from one side in the Y direction. Therefore, according to the laser processing method of the present embodiment, the irradiation of the pulsed laser light can be facilitated as compared with the case where the pulsed laser light is not irradiated in the order of the processing regions 21.

[0083] 2.4 Explanation of the laser processing method of Modification Example 1 of Embodiment 1 Next, the laser processing method of Modification Example 1 of the present embodiment will be described. Note that the same components as those described above will be denoted by the same reference numerals, and redundant descriptions will be omitted unless otherwise specified.

[0084] FIG. 11 is a diagram for explaining the movement of the irradiation region 22 in the laser processing method of Modification Example 1. In this modification, the order of the processing regions 21 irradiated with the pulsed laser light in the second step is different from the order of the processing regions 21 irradiated with the pulsed laser light in the second step in Embodiment 1. As shown in FIG. 11, in this modification, as in Embodiment 1, as the first step, the irradiation region 22 is moved along the arrow a, and the laser light is irradiated onto the processing regions 21 one by one in order from one side in the Y direction. Next, the irradiation region 22 moves from one side to the other side in the X direction within the processing region 21 located at the end on the other side in the Y direction. Next, as the second step, the irradiation region 22 is moved along the arrow b, and the laser light is irradiated onto the processing regions 21 one by one in order from the other side in the Y direction.

[0085] Also in this modification, as shown in FIG. 5, the irradiation region 22a in the processing region 21 when the irradiation region 22 moves along the arrow b which is the second step overlaps with a part of the irradiation region 22 of the laser light in the first step that was irradiated immediately before in the processing region 21. Thereafter, until the entire processing region 21 is irradiated with the laser light, such a change in the processing region 21 irradiated with the laser light is repeated.

[0086] Since the laser processing method of this modification example includes the above-described first step and second step in the same manner as the laser processing method of Embodiment 1, it is possible to suppress deformation of the workpiece 20 due to heat and shorten the time required to form a plurality of recesses 30 in the workpiece 20.

[0087] 2.5 Explanation of the Laser Processing Method of Modification Example 2 of Embodiment 1 Next, the laser processing method of Modification Example 2 of the present embodiment will be described. Note that the same components as those described above are denoted by the same reference numerals, and redundant descriptions are omitted unless otherwise specified.

[0088] The laser processing method of this modification example further includes a third step performed between the first step and the second step, and a fourth step performed after the second step.

[0089] FIG. 12 is a diagram for explaining the movement of the irradiation region 22 in the laser processing method of this modification example. As shown in FIG. 12, in this modification example, as in Embodiment 1, as the first step, the irradiation region 22 is moved along the arrow a, and the laser beam is irradiated onto the processing region 21 one by one in order from one side in the Y direction. Next, the irradiation region 22 moves from one side to the other side in the X direction within the processing region 21 located at the end on the other side in the Y direction. Next, as the third step, the irradiation region 22 is moved along the arrow c, and the laser beam is irradiated onto the processing region 21 one by one in order from the other side in the Y direction.

[0090] FIG. 13 is a diagram showing an example of the irradiation region 22 in the second irradiation on the processing region 21 in this modification example. As shown in FIG. 13, the irradiation region 22a in the processing region 21 when the irradiation region 22 moves along the arrow a which is the first step is along the edge on one side in the X direction of the processing region 21. Also, the irradiation region 22c in the processing region 21 when the irradiation region 22 moves along the arrow c which is the third step is along the edge on the other side in the X direction of the processing region 21. In this example, the irradiation region 22a and the irradiation region 22c are in contact without overlapping. Note that in FIG. 13, for clarity, the irradiation regions 22a and 22c are slightly shifted with respect to the processing region 21.

[0091] Next, the irradiation area 22 moves from the other side in the X direction toward the one side within the processing area 21 located at one end in the Y direction. Next, as the second step, the irradiation area 22 is moved along arrow b, and the processing area 21 is irradiated with laser light one by one in order from one side in the Y direction.

[0092] FIG. 14 is a diagram showing an example of the irradiation area 22 in the third irradiation with respect to the processing area 21 in Modification 2. As shown in FIG. 14, the irradiation area 22b in the processing area 21 when the irradiation area 22 moves along arrow b which is the second step overlaps with a part of the irradiation area 22a. The center 23b of the irradiation area 22b is located between the center 23a of the irradiation area 22a and the center 23c of the irradiation area 22c. That is, the center 23c of the irradiation area 22c in the third step is located on the side opposite to the center 23a of the irradiation area 22a in the first step with respect to the center 23b of the irradiation area 22b in the second step. In FIG. 14, for ease of viewing, the irradiation areas 22a, 22b, and 22c are slightly shifted with respect to the processing area 21.

[0093] Next, the irradiation area 22 moves from the one side in the X direction toward the other side within the processing area 21 located at the other end in the Y direction. Next, as the fourth step, the irradiation area 22 is moved along arrow d, and the processing area 21 is irradiated with laser light one by one in order from the other side in the Y direction.

[0094] FIG. 15 is a diagram showing an example of the irradiation area 22 in the fourth irradiation with respect to the processing area 21 in Modification 2. As shown in FIG. 15, the irradiation area 22d in the processing area 21 when the irradiation area 22 moves along arrow d which is the fourth step overlaps with a part of the irradiation area 22c in the third step. The center 23d of the irradiation area 22d in the fourth step is located between the center 23b of the irradiation area 22b in the second step and the center 23c of the irradiation area 22c in the third step. Thereafter, such a change in the processing area 21 irradiated with laser light is repeated. In FIG. 15, for ease of viewing, the irradiation areas 22a, 22b, 22c, and 22d are slightly shifted with respect to the processing area 21.

[0095] Since the laser processing method of this modification includes the above-described first step and second step in the same manner as the laser processing method of Embodiment 1, it is possible to suppress deformation of the workpiece 20 due to heat and shorten the time required to form a plurality of recesses 30 in the workpiece 20. Further, the laser processing method of this modification further includes the above-described third step and fourth step. Therefore, compared with the case where the third step and the fourth step are not provided, in each processing region 21, the region overlapping with the irradiation region 22 irradiated immediately before among the irradiation regions 22 can be reduced. Therefore, deformation of the workpiece 20 due to heat can be further suppressed.

[0096] Note that the order of the processing regions 21 irradiated with the pulsed laser light in the first step, the second step, the third step, and the fourth step may be different from the arrangement order of the processing regions 21.

[0097] 3. Description of the Laser Processing System and Laser Processing Method of Embodiment 2 Next, the laser processing system 10 and the laser processing method of Embodiment 2 will be described. Note that the same components as those described above are denoted by the same reference numerals, and redundant descriptions are omitted unless otherwise specified.

[0098] 3.1 Configuration FIG. 16 is a schematic diagram showing a schematic configuration example of the laser processing apparatus 300 of the present embodiment. As shown in FIG. 16, the laser processing apparatus 300 of the present embodiment is different from the laser processing apparatus 300 of Embodiment 1 in that it further includes a splitting optical system 380, high reflection mirrors 331d, 331e, galvanoscanners 363, 364, and an fθ lens 371.

[0099] The splitting optical system 380 is disposed on the optical path between the mask 335 and the high reflection mirror 331b. The splitting optical system 380 includes, for example, a beam splitter 381, reflects a part of the laser light from the mask 335 toward the high reflection mirror 331d, and transmits the rest. The transmitted light that has passed through the beam splitter 381 is reflected by the high reflection mirror 331b toward the high reflection mirror 331e. In this way, the splitting optical system 380 splits the laser light from the mask 335 into two laser lights La and Lb.

[0100] The configurations of the high-reflection mirrors 331d and 331e are the same as those of the high-reflection mirrors 331a, 331b, and 331c, for example. The high-reflection mirror 331d reflects the laser beam Lb from the beam splitter 381 toward the galvanometer scanner 363, and the high-reflection mirror 331e reflects the laser beam La from the high-reflection mirror 331b toward the galvanometer scanner 361. The mirror 361b of the galvanometer scanner 361 reflects the laser beam La from the high-reflection mirror 331e toward the mirror 362b, and the mirror 362b reflects the laser beam La from the mirror 361b toward the fθ lens 370. That is, the galvanometer scanners 361 and 362 are provided for the laser beam La. The fθ lens 370 focuses the laser beam La irradiated from the galvanometer scanner 362 onto the surface of the workpiece 20 along the optical axis of the fθ lens 370.

[0101] The configurations of the galvanometer scanners 363 and 364 are the same as those of the galvanometer scanner 361, and the galvanometer scanners 363 and 364 include drive units 363a and 364a and mirrors 363b and 364b. The mirror 363b reflects the laser beam Lb from the high-reflection mirror 331d toward the mirror 364b, and the mirror 364b reflects the laser beam Lb from the mirror 363b toward the fθ lens 371. That is, the galvanometer scanners 363 and 364 are provided for the laser beam Lb.

[0102] The galvanometer scanner 363 can move the irradiation region 22 of the laser beam Lb in the X direction by changing the optical path of the laser beam Lb with the mirror 363b. The galvanometer scanner 364 can move the irradiation region 22 of the laser beam Lb in the Y direction by changing the optical path of the laser beam Lb with the mirror 364b. That is, the galvanometer scanner 363 is a first moving unit that can move the irradiation region 22 of the laser beam Lb in the X direction perpendicular to the irradiation direction of the laser beam Lb. Also, the galvanometer scanner 364 is a second moving unit that can move the irradiation region 22 of the laser beam Lb in the Y direction perpendicular to the irradiation direction of the laser beam Lb.

[0103] The configuration of the fθ lens 371 is the same as that of the fθ lens 370, for example. The fθ lens 371 is disposed on the optical path between the mirror 364b and the workpiece 20, and the optical axis of the fθ lens 371 is along the Z direction. The fθ lens 371 condenses the laser beam Lb irradiated from the galvanometer scanner 364 onto the surface of the workpiece 20 along the optical axis of the fθ lens 371.

[0104] FIG. 17 is a view showing the surface of the workpiece 20 of the present embodiment. As shown in FIG. 17, in the present embodiment, a plurality of processing regions 21 are arranged in two rows in the Y direction. The processing regions 21 in one row 26 are regions to be processed by the irradiation of the laser beam La from the fθ lens 370, and the processing regions 21 in the other row 27 are regions to be processed by the irradiation of the laser beam Lb from the fθ lens 371. The number of processing regions 21 in one row is the same as the number of processing regions 21 in the other row.

[0105] 3.2 Operation Next, the operation of the laser processing system 10 and the laser processing method of the present embodiment will be described.

[0106] Similar to the first embodiment, the laser processing processor 310 of the present embodiment controls the galvanometer scanners 361 and 362 to move the irradiation region 22 of the laser beam La from the fθ lens 370, and irradiates the processing region 21 in one row 26 with the laser beam La. The laser beam La is irradiated onto different processing regions 21 for each pulse. Further, the laser processing processor 310 controls the galvanometer scanners 363 and 364 in the same manner as the galvanometer scanners 361 and 362 to move the irradiation region 22 of the laser beam Lb from the fθ lens 371, and irradiates the processing region 21 in the other row 27 with the laser beam Lb. The laser beam Lb is irradiated onto different processing regions 21 for each pulse. The control of the galvanometer scanners 361 and 362 and the control of the galvanometer scanners 363 and 364 are performed synchronously. Further, the laser beams La and Lb are laser beams split by the beam splitting optical system 380. For this reason, the laser beams La and Lb are simultaneously irradiated onto two of the plurality of processing regions 21.

[0107] 3.3 Function and Effect The laser processing method of this embodiment, similar to the laser processing method of Embodiment 1, includes a first step of irradiating pulsed laser light to different processing regions 21 for each pulse, and a second step of irradiating pulsed laser light to different processing regions 21 for each pulse so as to overlap a part of the irradiation region 22 of the pulsed laser light in the first step. Therefore, according to the laser processing method of this embodiment, similar to the laser processing method of Embodiment 1, deformation of the workpiece 20 due to heat can be suppressed, and the time required to form a plurality of recesses 30 in the workpiece 20 can be shortened. Further, in the laser processing method of this embodiment, in the first step and the second step, pulsed laser light is simultaneously irradiated to two of the plurality of processing regions 21. Therefore, according to the laser processing method of this embodiment, the time required to form a plurality of recesses 30 in the workpiece 20 can be made shorter.

[0108] Note that the splitting optical system 380 may split the laser light from the mask 335 into three or more laser lights. In this case, for example, two galvanoscanners are provided for each of the split laser lights. According to such a configuration, in the first step and the second step, pulsed laser light can be simultaneously irradiated to three or more of the plurality of processing regions 21. Note that the number of splits of the laser light is preferably not more than half of the number of the processing regions 21, and preferably, an integral multiple of the number of splits of the laser light is the same as the number of the processing regions 21.

[0109] Further, at least one of the movement of the laser lights La and Lb in the X direction and the movement of the irradiation region 22 in the Y direction may be performed by the stage 350.

[0110] Although the present invention has been described by taking embodiments as examples, the above embodiments can be changed as appropriate. For example, in Embodiment 1, the outer shape of the laser light irradiated to the workpiece 20 was a rectangular shape that was long in the Y direction, but it may be a shape other than the rectangular shape, for example, a circular shape.

[0111] Also, the arrangement direction of the plurality of workpieces 20 is not limited. For example, the plurality of workpieces 20 may be arranged in the X direction. Also, the plurality of workpieces 20 may not be arranged in a predetermined direction.

[0112] The above description is intended as an illustration and not a limitation. Thus, it will be apparent to those skilled in the art that changes may be made to the embodiments of the present disclosure without departing from the scope of the claims. Also, it will be apparent to those skilled in the art that the embodiments of the present disclosure may be used in combination. The terms used throughout this specification and the claims should be construed as "non-limiting" terms unless otherwise specified. For example, terms such as "including", "having", "comprising", "equipped with" should be construed as not excluding the presence of components other than those described. Also, the modifier "one" should be construed to mean "at least one" or "one or more". Also, the term "at least one of A, B, and C" should be construed as "A", "B", "C", "A + B", "A + C", "B + C", or "A + B + C", and further should be construed to include combinations with things other than "A", "B", and "C".

Claims

1. A laser processing method for forming a plurality of recesses by irradiating a plurality of processing regions separated from each other on the surface of a workpiece with pulsed laser light, comprising: a first step of irradiating the pulsed laser light to different ones of the processing regions for each pulse; a second step of irradiating the pulsed laser light to different ones of the processing regions for each pulse so as to overlap a part of the irradiation region of the pulsed laser light in the first step; and a laser processing method.

2. The laser processing method according to claim 1, wherein the plurality of processing regions are arranged in a predetermined direction, in the first step, the pulsed laser light is irradiated to the processing regions in order from one side in the predetermined direction, and in the second step, the pulsed laser light is irradiated to the processing regions in order from the other side in the predetermined direction.

3. The laser processing method according to claim 1, wherein the plurality of processing regions are arranged in a predetermined direction, and in the first step and the second step, the pulsed laser light is irradiated to the processing regions in order from one side in the predetermined direction.

4. The laser processing method according to claim 1, further comprising: a third step of irradiating the pulsed laser light to different ones of the processing regions for each pulse between the first step and the second step; and a fourth step of irradiating the pulsed laser light to different ones of the processing regions for each pulse after the second step, wherein, in each of the processing regions, the center of the irradiation region in the third step is located on the side opposite to the center of the irradiation region in the first step with respect to the center of the irradiation region in the second step, and the center of the irradiation region in the fourth step is located between the center of the irradiation region in the third step and the center of the irradiation region in the second step.

5. The laser processing method according to claim 4, wherein the plurality of processing regions are arranged in a predetermined direction, in the first step and the second step, the pulsed laser light is irradiated to the processing regions in order from one side in the predetermined direction, and in the third step and the fourth step, the pulsed laser light is irradiated to the processing regions in order from the other side in the predetermined direction.

6. The laser processing method according to claim 1, wherein in the first step and the second step, the pulsed laser light is irradiated to two or more of the plurality of processing regions simultaneously.

7. The laser processing method according to claim 1, wherein the workpiece is a light-transmissive plate-like member serving as an optical waveguide substrate.

8. The laser processing method according to claim 7, wherein the material constituting the plate-like member is a polyimide resin or a polynorbornene resin.

9. The laser processing method according to claim 7, wherein a portion on the direction side from the center of the irradiation region in the first step toward the center of the irradiation region in the second step among the edge portions of the recess after the first step and the second step is an inclined surface.

10. The laser processing method according to claim 1, wherein the outer shape of the pulsed laser light is rectangular, the irradiation region in the second step is a region where the irradiation region in the first step has moved in the short side direction of the outer shape of the pulsed laser light.

11. The laser processing method according to claim 10, wherein the width of the processing region in the direction from the center of the irradiation region in the first step toward the center of the irradiation region in the second step is twice the width in the short side direction of the pulsed laser light.

12. A laser processing system for irradiating a plurality of processing regions spaced apart from each other on the surface of a workpiece with pulsed laser light to form a plurality of recesses, comprising: a gas laser device that emits the pulsed laser light; a moving unit capable of moving the irradiation region of the pulsed laser light on the surface; a processor; and wherein the processor performs a first control of controlling the moving unit and the gas laser device to irradiate the pulsed laser light to different processing regions for each pulse; and a second control of controlling the moving unit and the gas laser device to irradiate the pulsed laser light to different processing regions for each pulse so as to overlap a part of the irradiation region of the pulsed laser light in the first control. is performed Laser processing system.

13. The laser processing system according to claim 12, wherein the moving unit includes a first moving unit capable of moving the irradiation region in a first direction and a second moving unit capable of moving the irradiation region in a second direction perpendicular to the first direction.

14. The laser processing system according to claim 13, wherein the first moving unit is a galvanometer scanner that changes the optical path of the pulsed laser light along the first direction, and the processor, in the second control, controls the galvanometer scanner to position the optical path of the pulsed laser light on the first direction side from the optical path in the first control.

15. The laser processing system according to claim 13, wherein The first moving part is a stage including a table that supports the workpiece and is movable in the first direction. In the second control, the processor controls the stage to position the workpiece on the first direction side of the workpiece in the first control. **Claim 16** The laser processing system according to claim 13, The plurality of processing regions are arranged along the second direction. The second moving part is a galvanometer scanner that changes the optical path of the pulsed laser beam along the second direction.

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