Laser processing method and laser processing system

Abstract

The invention provides a laser processing method and a laser processing system. 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 an object to be processed with pulsed laser light includes: a first step of irradiating the pulsed laser light to different processing regions for each pulse; and a second step in which the pulse laser light is irradiated to different processing regions for each pulse so as to overlap with a part of the irradiation region of the pulse laser light in the first step.

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, with the miniaturization and high integration of semiconductor integrated circuits, an improvement in resolution has been required. Therefore, the shortening of the wavelength of light emitted from an exposure light source has been promoted. For example, as a gas laser apparatus for exposure, a KrF excimer laser apparatus that emits laser light with an output wavelength of about 246.0 nm and an ArF excimer laser apparatus that emits laser light with an output wavelength of about 193.4 nm are used.

[0003] The spectral line width of the spontaneous oscillation light of a KrF excimer laser apparatus and an ArF excimer laser apparatus is as wide as 350 pm to 400 pm. Therefore, when a projection lens is made of a material that transmits ultraviolet light such as KrF and ArF lasers, chromatic aberration may occur. As a result, the resolution may be reduced. Therefore, it is necessary to narrow the spectral line width of the laser output from the gas laser apparatus to a level where chromatic aberration can be ignored. Therefore, in the laser resonator of the gas laser apparatus, in order to narrow the spectral line width, a narrowing module (Line Narrowing Module: LNM) including a narrowing element (etalon, grating, etc.) is sometimes provided. Hereinafter, a gas laser apparatus whose spectral line width is narrowed will be referred to as a narrowed gas laser apparatus.

[0004] [Prior Art Documents]

[0005] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2023-022603

[0007] [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-186185

[0008] [Patent Document 3] U.S. Patent Application Publication No. 2002 / 0064345 Summary of the Invention

[0009] A laser processing method according to one aspect of the present disclosure irradiates a plurality of processing regions separated from each other on the surface of a workpiece with pulsed laser light to form a plurality of recesses, wherein the laser processing method includes: 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 in such a manner that a part of the irradiation region of the pulsed laser light in the first step overlaps.

[0010] A laser processing system according to one aspect of the present disclosure irradiates pulsed laser onto a plurality of processing regions separated from each other on the surface of a workpiece to form a plurality of recesses. The laser processing system includes: a gas laser device that emits pulsed laser; a moving unit that can move the irradiation region of the pulsed laser on the surface; and a processor that performs: a first control for controlling the moving unit and the gas laser device to irradiate the pulsed laser onto different processing regions for each pulse; and a second control for controlling the moving unit and the gas laser device to irradiate the pulsed laser onto different processing regions for each pulse in such a manner as to overlap a part of the irradiation region of the pulsed laser in the first control. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Hereinafter, several embodiments of the present disclosure will be described with reference to the drawings only by way of example.

[0012] Figure 1 It is a schematic diagram showing a schematic overall structure example of a laser processing system of a comparative example.

[0013] Figure 2 It is a diagram for explaining the processing order on the surface of the workpiece.

[0014] Figure 3 It is a diagram showing an example of the irradiation region in the first irradiation of the processing region.

[0015] Figure 4 It is a cross-sectional view showing the state of the workpiece after the first irradiation of the processing region.

[0016] Figure 5 It is a diagram showing an example of the irradiation region in the second irradiation of the processing region.

[0017] Figure 6 It is a cross-sectional view showing the state of the workpiece after the second irradiation of the processing region.

[0018] Figure 7 It is a cross-sectional view showing the state of the workpiece after irradiating the entire processing region with laser.

[0019] Figure 8 It is a schematic diagram showing a schematic overall structure example of the laser processing apparatus of Embodiment 1.

[0020] Figure 9 It is a diagram showing the control flow of the laser processing processor of Embodiment 1.

[0021] Figure 10 It is a diagram for explaining the movement of the irradiation region in Embodiment 1.

[0022] Figure 11It is a diagram for explaining the movement of the irradiation area in the laser processing method of Modification 1 of Embodiment 1.

[0023] Figure 12 It is a diagram for explaining the movement of the irradiation area in the laser processing method of Modification 2 of Embodiment 1.

[0024] Figure 13 It is a diagram showing an example of the irradiation area in the second irradiation of the processing area in Modification 2 of Embodiment 1.

[0025] Figure 14 It is a diagram showing an example of the irradiation area in the third irradiation of the processing area in Modification 2 of Embodiment 1.

[0026] Figure 15 It is a diagram showing an example of the irradiation area in the fourth irradiation of the processing area in Modification 2 of Embodiment 1.

[0027] Figure 16 It is a schematic diagram showing a schematic structure example of the laser processing apparatus of Embodiment 2.

[0028] Figure 17 It is a diagram showing the surface of the workpiece of Embodiment 2. Detailed implementation

[0029] 1. Description of the laser processing system and laser processing method of the comparative example

[0030] 1.1 Structure

[0031] 1.2 Operation

[0032] 1.3 Problem

[0033] 2. Description of the laser processing system and laser processing method of Embodiment 1

[0034] 2.1 Structure

[0035] 2.2 Operation

[0036] 2.3 Function and effect

[0037] 2.4 Description of the laser processing method of Modification 1 of Embodiment 1

[0038] 2.5 Description of the laser processing method of Modification 2 of Embodiment 1

[0039] 3. Description of the laser processing system and laser processing method of Embodiment 2

[0040] 3.1 Structure

[0041] 3.2 Operation

[0042] 3.3 Functions and Effects

[0043] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The embodiments described below represent several examples of the present disclosure and do not limit the content of the present disclosure. In addition, the structures and operations described in each embodiment are not necessarily all essential as the structures and operations of the present disclosure. Furthermore, the same reference numerals are assigned to the same components, and repeated descriptions are omitted.

[0044] 1. Description of the Laser Processing System and Laser Processing Method of the Comparative Example

[0045] 1.1 Structure

[0046] The laser processing system and laser processing method of the comparative example will be described. In addition, the comparative example of the present disclosure is a method known only to the applicant, not a publicly known example considered by the applicant.

[0047] Figure 1 It is a schematic diagram showing a schematic structure example of the whole 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 connecting the gas laser device 100 and the laser processing device 300. Hereinafter, the direction parallel to the optical axis direction of the laser incident on the workpiece 20 will be set as the Z direction, the first direction orthogonal to the Z direction will be set as the X direction, and the second direction orthogonal to the X direction and the Z direction will be set as the Y direction for description. The Z direction is also the height direction of the workpiece 20.

[0048] The gas laser device 100 of this example is an ArF excimer laser device using a mixed gas containing argon (Ar), fluorine (F2), and neon (Ne). The gas laser device 100 outputs a laser with a central wavelength of about 193.4 nm. In addition, the gas laser device 100 may also be a gas laser device other than the ArF excimer laser device. For example, it may also be a KrF excimer laser device using a mixed gas containing krypton (Kr), F2, and Ne. In this case, the gas laser device 100 emits a laser with a central wavelength of about 246.0 nm. Sometimes, the mixed gas containing Ar, F2, and Ne as the laser medium and the mixed gas containing Kr, F2, and Ne as the laser medium are called laser gases.

[0049] The gas laser device 100 mainly includes a housing 110, a laser oscillator 130 disposed in the internal space of the housing 110, a monitoring module 150, a diaphragm 170, and a laser processor 190.

[0050] 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 Figure 1 it, the internal structure of the laser chamber 131 is shown as viewed from a direction substantially perpendicular to the traveling direction of the laser.

[0051] The laser chamber 131 includes an internal space that generates light through the excitation of a laser medium in the above-described laser gas. This light travels toward the windows 139a and 139b described later. Laser gas is supplied to the internal space of the laser chamber 131 from a laser gas supply source (not shown) through a pipe (not shown). In addition, the laser gas in the laser chamber 131 is subjected to a process of removing F2 gas by a halogen filter, and is exhausted to the housing 110 by an exhaust pump (not shown) through a pipe (not shown).

[0052] 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 traveling direction of the light. The electrodes 133a and 133b are discharge electrodes for exciting the laser medium through glow discharge. In this example, the electrode 133a is the cathode, and the electrode 133b is the anode.

[0053] The electrode 133a is supported by an electrical insulation part 135. The electrical insulation part 135 plugs 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 a return plate 137, and the return plate 137 is connected to the inner surface of the laser chamber 131 through wiring (not shown).

[0054] The charger 141 is a DC power supply device that charges a charging capacitor (not shown) in the pulse power module 143 with a prescribed voltage. The pulse power module 143 includes a switch 143a controlled by a laser processor 190. When the switch 143a changes from off to on, the pulse power module 143 generates a pulsed high voltage based on the electric energy held in the charger 141, and applies this high voltage between the electrode 133a and the electrode 133b.

[0055] 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 it transitions to the ground state.

[0056] Windows 139a and 139b are provided in the laser chamber 131. Window 139a is located on one end side in the traveling direction of the laser in the laser chamber 131, window 139b is located on the other end side in this traveling direction, and windows 139a and 139b sandwich the space between electrode 133a and electrode 133b. Windows 139a and 139b are inclined at Brewster angles with respect to the traveling direction of the laser to suppress the reflection of the P-polarized light of the laser. The laser oscillated as described later is emitted to the outside of the laser chamber 131 through windows 139a and 139b. As described above, a pulsed high voltage is applied between electrode 133a and electrode 133b by the pulse power supply module 143, so this laser is a pulsed laser.

[0057] The rear mirror 145 is arranged in the internal space of the housing 145a connected to one end side of the laser chamber 131, reflects the laser emitted from window 139a and returns it to the laser chamber 131. The output coupling mirror 147 is arranged in the internal space of the optical path tube 147a connected to the other end side of the laser chamber 131, allows a part of the laser emitted from window 139b to pass through, and reflects the other part of the laser 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 arranged on the optical path of the laser resonator.

[0058] The monitoring module 150 is arranged on the optical path of the laser emitted from the output coupling mirror 147. The monitoring module 150 includes, for example, a housing 151, a beam splitter 153 arranged in the internal space of the housing 151, and a light sensor 155. An opening is formed in the housing 151, and the internal space of the housing 151 communicates with the internal space of the optical path tube 147a through this opening.

[0059] The beam splitter 153 allows a part of the laser emitted from the output coupling mirror 147 to pass through and then directs it toward the diaphragm 170, and reflects the other part of the laser toward the light receiving surface of the light sensor 155. The light sensor 155 measures the energy E of the laser incident on the light receiving surface. The light sensor 155 outputs a signal representing the measured energy E to the laser processor 190.

[0060] 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. In addition, the laser processor 190 controls the entire gas laser device 100.

[0061] 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 signals representing the light emission trigger Tr and the target energy Et (described later) from the laser processing processor 310. The laser processor 190 controls the charging voltage of the charger 141 based on the energy E received from the optical sensor 155 and the target energy Et received from the laser processing processor 310. The energy of the laser is controlled by controlling this charging voltage. In addition, the laser processor 190 sends an instruction signal for turning on or off the switch 143a to the pulse power supply module 143. In addition, the laser processor 190 is electrically connected to the aperture 170 and controls the opening and closing of the aperture 170.

[0062] The laser processor 190 closes the aperture 170 until the difference ΔE between the energy E received from the monitoring module 150 and the target energy Et received from the laser processing processor 310 is within an allowable range. If the difference ΔE is within the allowable range, the laser processor 190 sends a reception ready completion signal to the laser processing processor 310 to notify that the reception preparation for the light emission trigger Tr has been completed. When the laser processing processor 310 receives the reception ready completion signal, it sends a signal representing the light emission trigger Tr to the laser processor 190, and the laser processor 190 opens the aperture 170 when it receives the signal representing the light emission trigger Tr. The light emission trigger Tr is defined by a prescribed repetition frequency f and a prescribed number of pulses P of the laser, and is a timing signal for the laser processing processor 310 to cause the laser oscillator 130 to perform laser oscillation, and is an external trigger. The repetition frequency f of the laser is, for example, 1 kHz or more and 10 kHz or less.

[0063] The aperture 170 is disposed on the optical path of the laser that passes through the beam splitter 153 of the monitoring module 150 and then passes through an opening, and this opening is an opening formed in the housing 151 on the side opposite to the side to which the optical path tube 147a is connected. In addition, the aperture 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 above-mentioned opening and communicates with the housing 151. In addition, the optical path tube 171 communicates with the laser processing apparatus 300 through the above-mentioned opening of the housing 110 and the optical path tube PO.

[0064] The internal spaces of the optical path tube 171 and the optical path tube 147a, the housing 151 and the housing 145a are filled with a purge gas. The purge gas contains an inert gas such as nitrogen (N2). The purge gas is supplied from a purge gas supply source (not shown) to the internal spaces of the optical path tube 171 and the optical path tube 147a, the housing 151 and the housing 145a through a pipe (not shown).

[0065] The laser processing apparatus 300 includes a laser processing processor 310, an optical system 330, a stage 350, a housing 355, and a frame 357 as main components. The optical system 330 and the stage 350 are disposed 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. The laser that has passed through the diaphragm 170 is incident on the housing 355.

[0066] The laser processing processor 310 is a processing device including a storage device 310a that stores a control program and a CPU 310b that executes the control program. The laser processing processor 310 is specifically configured or programmed to execute various processes included in the present disclosure. The laser processing processor 310 controls the entire laser processing apparatus 300.

[0067] The optical system 330 includes high reflectors 331a, 331b, and 331c, an attenuator 332, a fly-eye lens 333, a converging lens 334, a mask 335, and a projection optical system 336. Each component of the optical system 330 is fixed to a holding member (not shown) and is disposed at a predetermined position within the housing 355.

[0068] The high reflectors 331a, 331b, and 331c are formed, for example, by coating a reflective film that highly reflects laser light on the surface of a transparent substrate made of synthetic quartz or calcium fluoride. The high reflector 331a reflects the laser light incident from the gas laser device 100 toward the attenuator 332. The high reflector 331b reflects the laser light from the attenuator 332 toward the high reflector 331c. The high reflector 331c reflects the laser light from the high reflector 331b toward the fly-eye lens 333.

[0069] The attenuator 332 is arranged on the optical path between the high reflector 331a and the high reflector 331b. The attenuator 332 includes, for example, rotary tables 332a, 332b and partial reflectors 332c, 332d fixed to the rotary tables 332a, 332b. Each of the rotary tables 332a, 332b is electrically connected to the laser processing processor 310 and rotates about the Y-axis according to a control signal from the laser processing processor 310. When the rotary tables 332a, 332b rotate respectively, the partial reflectors 332c, 332d also rotate respectively. The partial reflectors 332c, 332d are optical elements whose transmittance varies according to the incident angle of the laser Lb on the partial reflectors 332c, 332d. By rotating the rotary tables 332a, 332b, the rotation angles of the partial reflectors 332c, 332d rotating about the Y-axis are adjusted so that the incident angles of the lasers are the same as each other and the transmittance of the partial reflectors 332c, 332d becomes a desired transmittance. Thereby, the laser from the high reflector 331a is reduced in light intensity to a desired energy and passes through the attenuator 332.

[0070] The fly-eye lens 333 is a lens formed by arranging a plurality of lenses, for example, in a honeycomb pattern, and is also referred to as an integral lens. The fly-eye lens 333 is arranged so that the focal plane on the emission side of the fly-eye lens 333 coincides with the focal plane on the incident surface side of the converging lens 334, and emits light in such a way that the energy density of the laser incident on the converging lens 334 is uniform.

[0071] The converging lens 334 is a lens that converges the laser emitted from the fly-eye lens 333 and is arranged so that the focal plane on the emission side of the converging lens 334 is located on the mask 335.

[0072] The mask 335 is, for example, a plate-like member formed with a through-hole through which a part of the laser passes and blocking the other part of the laser. In this example, the through-hole is formed of a rectangular hole, and by making the laser pass through the through-hole, the outer shape of the laser becomes a long rectangle in the Y direction.

[0073] The projection optical system 336 includes, for example, a collimating lens 336a and a converging lens 336b. The collimating lens 336a emits the laser from the mask 335 as parallel light. The converging lens 336b converges the laser from the collimating lens 336a onto the surface of the workpiece 20.

[0074] The mounting table 350 is arranged on the bottom surface of the housing 355 and includes a worktable 351. In addition, the mounting table 350 can move the worktable 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 worktable 351 by this movement.

[0075] The workbench 351 supports the workpiece 20. The main surface of the workbench 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 arranged substantially along the XY plane. With the above structure, the mounting table 350 can move the workpiece 20 via the workbench 351 to adjust the position of the workpiece 20 so that a plurality of lasers emitted from the optical system 330 irradiate a desired position on the workpiece 20. That is, the mounting table 350 is a moving part that can move the irradiation area of the laser on the surface of the workpiece 20 in the X and Y directions perpendicular to the irradiation direction of the laser.

[0076] The workpiece 20 is an object to be laser-processed by laser irradiation. As the workpiece 20, for example, a light-transmissive plate-like member that becomes an optical waveguide substrate can be cited. As the material constituting the plate-like member, for example, polyimide resin and polynorbornene resin can be cited.

[0077] During the operation of the laser processing system 10, an inert gas always flows in the internal space of the housing 355. This inert gas is, for example, nitrogen. The housing 355 is provided with an intake port (not shown) for sucking 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. 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 tube PO communicating with the housing 355.

[0078] 1.2 Operations

[0079] Next, the operations and laser processing method of the laser processing system 10 of the comparative example will be described.

[0080] In the gas laser device 100, in a state before the gas laser device 100 emits laser light, a purge gas is filled into the internal spaces of the optical path tubes 147a, 171, PO and the internal spaces of the housings 145a, 151 from a purge gas supply source (not shown). In addition, a laser gas is supplied into the internal space of the laser chamber 131 from a laser gas supply source (not shown). In addition, in the laser processing device 300, an inert gas such as nitrogen flows in the internal space of the housing 355.

[0081] In the laser processing apparatus 300, the workpiece 20 is supported on the worktable 351. The laser processing processor 310 sets the coordinates X, Y, and Z of the initial irradiation position for irradiating the laser to form the processed part on the mounting table 350. Thereby, the mounting table 350 moves the worktable 351 together with the workpiece 20 to the set initial irradiation position. In addition, the irradiation position refers to the position of the center of the irradiation area where the laser is irradiated.

[0082] After the worktable 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 irradiated to the workpiece 20 becomes the desired energy density F required for laser processing. The energy density F is defined by the value obtained by dividing the energy of the laser by the cross-sectional area of the laser perpendicular to the optical axis of the laser.

[0083] The laser processor 190 closes the aperture 170 and drives the charger 141. In addition, the laser processor 190 turns on the switch 143a of the pulse power supply module 143. Thereby, the pulse power supply module 143 applies a pulsed high voltage between the electrode 133a and the electrode 133b using the electric energy held in the charger 141. Through this high voltage, a discharge is generated 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 becomes an excited state, and light is emitted when the laser medium returns to the ground state. Through this light, optical resonance occurs 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, causing laser oscillation. Then, a part of the laser passes through the output coupling mirror 147 as pulsed laser light and travels toward the beam splitter 153.

[0084] A part of the laser that travels 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 and outputs a signal representing 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 the allowable range. After the difference ΔE is within the allowable range, the laser processor 190 sends a reception ready completion signal indicating that the reception preparation for the light emission trigger Tr has been completed to the laser processing processor 310.

[0085] When the laser processing processor 310 receives the reception ready completion signal, it sends the light emission trigger Tr to the laser processor 190. When the laser processor 190 opens the aperture 170 in synchronization with the reception of the light emission trigger Tr, the laser that has passed through the aperture 170 enters the laser processing apparatus 300. This laser is, for example, pulsed laser light with a center wavelength of 193.4 nm.

[0086] The laser incident on the laser processing apparatus 300 is irradiated onto the mask 335 via the high reflector 331a, the attenuator 332, the high reflectors 331b and 331c, the fly-eye lens 333, and the condenser lens 334. At this time, the laser is Kohler-illuminated onto the mask 335. In the mask 335, a part of the laser passes through the through-hole and becomes a laser beam having a rectangular shape elongated in the Y direction, and the other part of the laser is blocked. The laser passing through the mask 335 is made parallel by the collimator lens 336a of the projection optical system 336, and is condensed onto the surface of the workpiece 20 by the condenser lens 336b.

[0087] The laser is irradiated onto the workpiece 20 according to the emission trigger Tr specified 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, and defects are generated. Thereby, the processed portion is processed on the workpiece 20 to form a concave portion. In this example, a plurality of processed portions separated from each other are processed to form a plurality of concave portions.

[0088] Figure 2 It is a diagram for explaining the processing sequence on the surface of the workpiece 20. Figure 2 The processing region 21 shown is a region where the laser is irradiated for processing. In this example, a plurality of processing regions 21 are arranged separately from each other in the Y direction. The outer shape of the processing region 21 is a substantially rectangular shape including opposite sides opposed in the X direction and opposite sides opposed in the Y direction. The width of the processing region 21 in the Y direction is substantially the same as the width of the irradiation region 22 where the laser is irradiated with one pulse in the Y direction, and the width of the processing region 21 in the X direction is wider than the width of the irradiation region 22 in the X direction, and is approximately twice that width. Therefore, by irradiating the laser multiple times, the entire processing region 21 is irradiated with the laser. In Figure 2 In order to distinguish the processing region 21 from the irradiation region 22, a shadow composed of a plurality of dots is added to the irradiation region 22. In addition, the description of several processing regions 21 is omitted.

[0089] Figure 3 It is a diagram showing an example of the irradiation region 22 in the first irradiation of the processing region 21, Figure 4 It is a cross-sectional view showing the state of the workpiece 20 after the first irradiation of the processing region 21. As Figure 3 shown, in this example, first, the workpiece 20 is moved by the mounting table 350 so that the irradiation region 22 is along the edge on one side in the X direction of the processing region 21, and the surface of the workpiece 20 is irradiated with the laser. Therefore, the laser is irradiated onto the irradiation region 22, and as Figure 4 shown, a concave portion 25 is formed in the workpiece 20.

[0090] Figure 5FIG. is an example of the irradiation area 22 in the second irradiation of the processing area 21. Figure 6 FIG. is a cross-sectional view showing the state of the workpiece 20 after the second irradiation of the processing area 21. After the first irradiation of the processing area 21, as Figure 5 shown, the workpiece 20 is moved to one side in the X direction by the mounting table 350, and the surface of the workpiece 20 is irradiated with laser light. At this time, the irradiation area 22a of the laser light irradiated overlaps a part of the irradiation area 22 of the laser light irradiated immediately before, and the center 23a of the irradiation area 22a is located on the other side in the X direction than the center 23 of the irradiation area 22. The irradiation area 22a is the area after the irradiation area 22a that overlaps the irradiation area 22 is moved in the short side direction of the outer shape of the laser light. In addition, the direction from the center 23a of the irradiation area 22a to the center 23 of the irradiation area 22 that overlaps the irradiation area 22a is the X direction, and the width of the processing area 21 in this X direction is twice the width in the short side direction of the laser light. In Figure 5 in order to distinguish between the irradiation area 22 and the irradiation area 22a, a shadow composed of a plurality of points is added to the irradiation area 22, and a shadow composed of a plurality of oblique lines is added to the irradiation area 22a.

[0091] By irradiating the irradiation area 22a with laser light, as Figure 6 shown, another recess 25 is formed in the workpiece 20. Since the irradiation area 22a overlaps a part of the irradiation area 22 of the laser light irradiated immediately before, a part of the edge of the irradiation area 22 is located within the irradiation area 22a. The corner part is more easily processed by the laser light than the planar part. Therefore, the corner part along the edge of the irradiation area 22 located within the irradiation area 22a is more easily processed than other parts and becomes a chamfered shape.

[0092] Figure 7 FIG. is a cross-sectional view showing the state of the workpiece 20 after irradiating the entire processing area 21 with laser light. The movement of the irradiation area 22 of the laser light and the irradiation of the laser light are repeated until the irradiation area 22 of the laser light reaches the edge on the other side in the X direction of the processing area 21. In this way, by forming a plurality of recesses 25, the recess 30 as shown in Figure 7 is formed. As described above, the corner part is more easily processed by the laser light than the planar part, and the laser light is irradiated multiple times on the part on the other side in the X direction of the edge of the recess 25. Therefore, the part on the other side in the X direction of the edge of the recess 30 becomes a substantially flat inclined surface 31, and the part on the one side in the X direction of the edge of the recess 30 becomes a stepped shape. The inclined surface 31 is the surface of the optical waveguide substrate provided with the reflective film that becomes the micromirror. In this example, the recess 30 is not a through hole that penetrates to the back surface of the workpiece 20, but it can also be a through hole.

[0093] Next, the workpiece 20 is moved by the mounting table 350 in such a manner that the irradiation region 22 follows the edge on one side in the X direction of the other processing region 21, and the above-described laser irradiation and movement of the irradiation region 22 are repeated. In this example, the processing regions 21 irradiated with the laser are sequentially changed from one side in the Y direction. Thus, a plurality of recesses 30 are formed in the workpiece 20.

[0094] 1.3 Problem

[0095] In the processing performed by the laser processing apparatus 300 of the comparative example, since the process of irradiating the laser in such a manner as to overlap a part of the immediately preceding irradiation region 22 is repeated, the workpiece 20 is overheated, and sometimes the workpiece 20 is deformed due to this heat.

[0096] Therefore, in the following embodiments, a laser processing system 10 and a laser processing method capable of suppressing deformation of the workpiece 20 caused by heat are exemplified.

[0097] 2. Description of the Laser Processing System and Laser Processing Method of Embodiment 1

[0098] The laser processing system 10 and the laser processing method of Embodiment 1 will be described. In addition, the same reference numerals are given to the structures having the same configuration as those described above, and the repeated description is omitted except in special cases.

[0099] 2.1 Structure

[0100] Figure 8 It is a schematic diagram showing a schematic configuration example of the laser processing apparatus 300 of the present embodiment. As Figure 8 shown, in the laser processing apparatus 300 of 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. In addition, the laser processing apparatus 300 of the present embodiment includes Galvano scanners 361 and 362 instead of the high reflector 331c, and includes an fθ lens 370 instead of the projection optical system 336.

[0101] 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 reflector 331b.

[0102] The galvanometer scanner 361 includes a drive unit 361a and a mirror 361b that is mounted on the swing axis of the drive unit 361a and can swing around the swing axis. In addition, the structure of the galvanometer scanner 362 is the same as that of the galvanometer scanner 361. The galvanometer scanner 362 includes a drive unit 362a and a mirror 362b that is mounted on the swing axis of the drive unit 362a and can swing around the swing axis.

[0103] 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 a control signal 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.

[0104] The mirror 361b reflects the laser from the high reflector 331b toward the mirror 362b, and the mirror 362b reflects the laser from the mirror 361b toward the fθ lens 370. The orientations of the mirrors 361b and 362b are adjusted by the swing angles of the swing axes of the drive units 361a and 362a, respectively. The adjustment of the orientations of the mirrors 361b and 362b can also be synchronized. The speeds of the mirrors 361b and 362b during swinging are adjusted by the swing speeds when the swing axes of the drive units 361a and 362a swing.

[0105] The galvanometer scanner 361 changes the optical path of the laser along the X direction through the mirror 361b, and can move the irradiation area 22 of the laser in the X direction. The galvanometer scanner 362 changes the optical path of the laser along the Y direction through the mirror 362b, and can move the irradiation area 22 of the laser in the Y direction. That is, the galvanometer scanner 361 is a first moving unit that can move the irradiation area 22 of the laser in the X direction perpendicular to the irradiation direction of the laser. In addition, the galvanometer scanner 362 is a second moving unit that can move the irradiation area 22 of the laser in the Y direction perpendicular to the irradiation direction of the laser. The minimum moving distance of the irradiation area 22 that the galvanometer scanner 361 can adjust is substantially the same as the minimum moving distance of the irradiation area 22 that the galvanometer scanner 362 can adjust.

[0106] The fθ lens 370 is on the optical path between the mirror 362b and the workpiece 20, is fixed to a holding member (not shown), and is disposed at a specified position in the housing 355. The optical axis of the fθ lens 370 is along the Z direction. The fθ lens 370 condenses the laser irradiated from the galvanometer scanner 362 onto the surface of the workpiece 20 along the optical axis of the fθ lens 370.

[0107] 2.2 Operations

[0108] Next, the operations of the laser processing processor 310 in the present embodiment will be described.

[0109] Figure 9 This is a diagram showing the control flow of the laser processing processor 310 of the present embodiment. The control flow of the present embodiment includes steps SP11 to SP18, representing a laser processing method for forming a plurality of recesses 30 in the workpiece 20. In addition, Figure 10 This is a diagram for explaining the movement of the irradiation area 22 in the present embodiment.

[0110] In Figure 9 In the shown starting state, the laser processing processor 310 has received the reception ready completion signal from the laser processor 190, but has not sent the light emission trigger Tr to the laser processor 190. Therefore, although the laser is emitted from the laser oscillator 130, since the aperture 170 is closed, the laser does not enter the laser processing device 300 from the gas laser device 100. In addition, in the starting state, the workpiece 20 has already been supported on the worktable 351.

[0111] (Step SP11)

[0112] This step is a preparation step before the laser processing device 300 officially operates. 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 areas 21, the maximum number mmax of times of irradiating the laser to each processing area 21, the number n, the irradiation number m, and the coordinates Xn,m of the irradiation position of the irradiated laser.

[0113] The processing areas 21 are assigned numbers from 1 to nmax. The number n is the number of the processing area 21, and the initial value of n is 1. In the present embodiment, the numbers increase in sequence starting from the processing area 21 at one end in the Y direction. The irradiation number m is the number indicating the number of times the laser is irradiated to each processing 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 is irradiated for the m-th time in the n-th processing area 21, and are the XY coordinates of the center 23 of the irradiation area 22 at this time. And for each processing area 21, there are mmax coordinates Xn,m of the irradiation position. In the present embodiment, the irradiation area 22 at the time of the coordinates Xn,1 is along the edge on one side in the X direction of the n-th processing area 21. As m increases, the coordinates Xn,m move from one side to the other side along the X direction. The moving distance of the coordinates Xn,m when m increases by 1 is fixed. Moreover, the irradiation area 22 at the time of the coordinates Xn,mmax is along the edge on the other side in the X direction of the n-th processing area 21. In addition, a part of the irradiation area 22 at the time of the coordinates Xn,m + 1 overlaps with the irradiation area 22 at the time of the coordinates Xn,m.

[0114] (Step SP12)

[0115] This step is to move the irradiation position of the laser. In this step, the laser processing processor 310 controls the galvanometer scanner 361 and the galvanometer scanner 362 so that the coordinates of the irradiation position become the coordinates Xn,m. When the laser processing processor 310 controls the galvanometer scanner 361 and the galvanometer scanner 362, it makes the control flow enter step SP13.

[0116] (Step SP13)

[0117] This step is to irradiate the workpiece 20 with the laser only once. In this step, the laser processing processor 310 sends a light emission trigger Tr to the laser processor 190 to cause the laser processor 190 to open the aperture 170. Thereby, the laser enters the laser processing device 300 from the gas laser device 100. The incident laser travels in the order of the high reflector 331a, the attenuator 332, the fly-eye lens 333, the condenser lens 334, the mask 335, the high reflector 331b, the mirror 361b, the mirror 362b, and the fθ lens 370 and irradiates the workpiece 20. When the workpiece 20 is processed by the irradiation of the laser and the laser is irradiated once, the laser processing processor 310 makes the control flow enter step SP14. In addition, in the present embodiment, the state where the aperture 170 is open is maintained until the processing of the workpiece 20 is completed, and the steps performed before returning to this step are performed during the period before the next laser enters the laser processing device 300 from the gas laser device 100.

[0118] (Step SP14)

[0119] This step is to make the next step different according to the number n. In this step, when the number n is less than nmax, the laser processing processor 310 makes the control flow enter step SP15, and when the number n is equal to or greater than nmax, it makes the control flow enter step SP16.

[0120] (Step SP15)

[0121] This step is to increment 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 process, it is performed along Figure 10The process of moving the irradiation area 22 by the indicated arrow a and irradiating each processing area 21 with laser once in sequence from one side in the Y direction. Since the movement of the irradiation area 22 is along the Y direction, in step SP12 during these irradiations, the laser processing processor 310 controls the galvanometer scanner 361 and the galvanometer scanner 362 to change the orientation of the mirror 361b of the galvanometer scanner 361 while maintaining the orientation of the mirror 362b of the galvanometer scanner 362. Then, when each processing area 21 has been irradiated with laser once, the control flow proceeds to step SP16.

[0122] (Step SP16)

[0123] 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 makes the control flow proceed to step SP17.

[0124] (Step SP17)

[0125] This step is to make the next step different according to the irradiation number m. In this step, when the irradiation number m is less than or equal to mmax, the laser processing processor 310 makes the control flow proceed to step SP18, and when the irradiation number m is greater than mmax, the control flow ends.

[0126] (Step SP18)

[0127] 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 makes the control flow return to step SP12. Therefore, when each of all the processing areas 21 has been irradiated with laser once, the irradiation area 22 moves to the processing area 21 at the end on one side in the Y direction. Then, as the second process, along Figure 10The process of moving the irradiation area 22 by the arrow b shown and irradiating the laser on each processing area 21 once in sequence from one side in the Y direction. As described above, the irradiation area 22 at the coordinates Xn, m + 1 overlaps with a part of the irradiation area 22 at the coordinates Xn, m. Therefore, when the irradiation number m is 2 or more, the irradiation area 22 overlaps with a part of the irradiation area 22 of the laser with the irradiation number m being m - 1. Therefore, the irradiation area 22 in the second process overlaps with a part of the irradiation area 22 of the pulsed laser in the first process. In addition, the irradiation area 22 at the coordinates Xn, m + 1 is the area after the irradiation area 22 at the coordinates Xn, m that overlaps with this irradiation area 22 is moved in the short side direction of the laser profile, i.e., the X direction. Therefore, the irradiation area 22 in the second process is the area after the irradiation area 22 in the first process is moved in the short side direction of the pulsed laser profile. That is, in the second process, the laser processing processor 310 controls the galvanometer scanner 361 to make the optical path of the pulsed laser located at a position on the X direction side compared to the optical path in the first process. Then, the movement of the irradiation area 22 and the irradiation of the laser are repeated until the irradiation number m becomes mmax or more, and recesses 30 are formed in each processing area 21.

[0128] In the above control process, when the control process returns from step SP17 to step SP12 in the state where the irradiation number m is an integer α, through the repetition of steps SP12, SP13, SP14, SP15, the pulsed laser is irradiated onto different processing areas 21 for each pulse. Therefore, the repetition of steps SP12, SP13, SP14, SP15 can be regarded as the first process. In this first process, the laser processing processor 310 controls the galvanometer scanners 361, 362 as the moving parts and performs the first control of irradiating the pulsed laser onto different processing areas 21 for each pulse. When the irradiation of the laser on the processing area 21 with the number nmax ends, in step SP16, the irradiation number m becomes α + 1, and in this state, the control process returns from step SP17 to step SP12. Thus, in the case of the control process, by repeating steps SP12, SP13, SP14, SP15, the pulsed laser is irradiated onto different areas for each pulse in such a way that it overlaps with a part of the irradiation area 22 of the pulsed laser in the first process. That is, the repetition of steps SP12, SP13, SP14, SP15 when the control process returns from step SP17 to step SP12 in the state where the irradiation number m is α + 1 can be regarded as the second process. In this second process, the laser processing processor 310 controls the galvanometer scanner 361 and the galvanometer scanner 362 as the moving parts and performs the second control of irradiating the pulsed laser onto different processing areas 21 for each pulse in such a way that it overlaps with a part of the irradiation area 22 of the pulsed laser in the first control.

[0129] 2.3 Functions and Effects

[0130] The laser processing method of this embodiment includes: a first process of irradiating pulsed laser to different processing regions 21 for each pulse; and a second process of irradiating pulsed laser to different processing regions 21 for each pulse in such a way that a part of the irradiation region 22 of the pulsed laser in the first process overlaps. In addition, in the laser processing system 10 of this embodiment, the laser processing processor 310 performs the above-mentioned first control corresponding to the first process and the above-mentioned second control corresponding to the second process. Therefore, according to the laser processing method and the laser processing system 10 of this embodiment, the situation of continuously irradiating pulsed laser to the same processing region 21 can be suppressed. Therefore, compared with the situation of continuously irradiating pulsed laser to the same processing region 21, overheating of the workpiece 20 can be suppressed, and deformation of the workpiece 20 caused by heat can be suppressed. In addition, the time interval of irradiating pulsed laser can be shortened, and the time spent on forming a plurality of recesses 30 in the workpiece 20 can be shortened.

[0131] In addition, the laser processing system 10 of this embodiment includes: a galvanometer scanner 361 that can move the irradiation region 22 of the laser in the X direction; and a galvanometer scanner 361 that can move the irradiation region 22 in the Y direction perpendicular to the X direction. In addition, a plurality of processing regions 21 are arranged along the Y direction. Moreover, the galvanometer scanner 361 moves the irradiation region 22 so that the irradiation region 22 is located in a processing region 21 different from the processing region 21 irradiated by the immediately preceding pulsed laser. The galvanometer scanner 361 can shorten the time spent on moving the irradiation region 22 compared with the stage 350 that moves the irradiation region 22 by moving the stage 351 that supports the workpiece 20. Therefore, according to the laser processing system 10 of this embodiment, compared with the situation of moving the irradiation region 22 between different processing regions 21 by the stage 350, the time spent on processing can be reduced. In addition, 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 can also 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, the laser processing processor 310 controls the stage 350 in the second process to position the workpiece 20 on the X direction side of the workpiece 20 in the first process.

[0132] In addition, in the laser processing method of the present embodiment, a plurality of processing regions 21 are arranged in the Y direction. In the first process and the second process, pulsed laser is irradiated on the processing regions 21 in sequence from one side in the Y direction. Therefore, according to the laser processing method of the present embodiment, compared with the case where the pulsed laser is not irradiated in the arrangement order of the processing regions 21, the irradiation of the pulsed laser can be made easier.

[0133] 2.4 Explanation of the laser processing method of Modification 1 of Embodiment 1

[0134] Next, the laser processing method of Modification 1 of the present embodiment will be described. In addition, the same reference numerals are given to the structures that are the same as those described above, and repeated descriptions are omitted unless otherwise specified.

[0135] Figure 11 FIG. is a diagram for explaining the movement of the irradiation region 22 in the laser processing method of Modification 1. In this modification, the order of the processing regions 21 irradiated with pulsed laser in the second process is different from the order of the processing regions 21 irradiated with pulsed laser in the second process of Embodiment 1. As Figure 11 shown, in this modification, as in Embodiment 1, as the first process, the irradiation region 22 is moved along the arrow a, and laser is irradiated on each of the processing regions 21 once in sequence from one side in the Y direction. Next, the irradiation region 22 moves from one side in the X direction to the other side within the processing region 21 at the end on the other side in the Y direction. Next, as the second process, the irradiation region 22 is moved along the arrow b, and laser is irradiated on each of the processing regions 21 once in sequence from the other side in the Y direction.

[0136] In this modification, as Figure 5 shown, when the irradiation region 22 moves along the arrow b as the second process, the irradiation region 22a in the processing region 21 also overlaps with a part of the irradiation region 22 of the laser in the first process irradiated immediately before in this processing region 21. After that, such a change of the processing region 21 irradiated with laser is repeated until laser has been irradiated on all of the processing regions 21.

[0137] The laser processing method of this modification also includes the above-mentioned first process and second process as in the laser processing method of Embodiment 1. Therefore, deformation of the workpiece 20 caused by heat can be suppressed, and the time required to form a plurality of recesses 30 in the workpiece 20 can be shortened.

[0138] 2.5 Explanation of the laser processing method of Modification 2 of Embodiment 1

[0139] Next, a laser processing method according to Modification 2 of the present embodiment will be described. In addition, the same reference numerals are assigned to the structures that are the same as those described above, and redundant descriptions are omitted unless otherwise specified.

[0140] The laser processing method of this modification further includes a third process performed between the first process and the second process and a fourth process performed after the second process.

[0141] Figure 12 This is a diagram for explaining the movement of the irradiation area 22 in the laser processing method of this modification. As Figure 12 shown, in this modification, as in the first embodiment, as the first process, the irradiation area 22 is moved along the arrow a, and the laser is irradiated on each of the processing areas 21 once in sequence from one side in the Y direction. Next, the irradiation area 22 moves from one side in the X direction toward the other side within the processing area 21 at the end on the other side in the Y direction. Next, as the third process, the irradiation area 22 is moved along the arrow c, and the laser is irradiated on each of the processing areas 21 once in sequence from the other side in the Y direction.

[0142] Figure 13 This is a diagram showing an example of the irradiation area 22 in the second irradiation of the processing area 21 in this modification. As Figure 13 shown, the irradiation area 22a in the processing area 21 when the irradiation area 22 moves along the arrow a as the first process is along the edge on one side in the X direction of the processing area 21. In addition, the irradiation area 22c in the processing area 21 when the irradiation area 22 moves along the arrow c as the third process is along the edge on the other side in the X direction of the processing area 21. In this example, the irradiation area 22a and the irradiation area 22c are in contact without overlapping. In addition, in Figure 13 for easy observation, the irradiation areas 22a and 22c are slightly offset from the processing area 21.

[0143] Next, the irradiation area 22 moves from the other side in the X direction toward one side within the processing area 21 at the end on one side in the Y direction. Next, as the second process, the irradiation area 22 is moved along the arrow b, and the laser is irradiated on each of the processing areas 21 once in sequence from one side in the Y direction.

[0144] Figure 14 This is a diagram showing an example of the irradiation area 22 in the third irradiation of the processing area 21 in Modification 2. As Figure 14As shown, when the irradiation area 22 moves along arrow b which represents the second process, a part of the irradiation area 22b in the processing area 21 overlaps with 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 process is located on the side opposite to the center 23a of the irradiation area 22a in the first process with respect to the center 23b of the irradiation area 22b in the second process. In addition, in Figure 14 for ease of observation, the irradiation areas 22a, 22b, and 22c are slightly offset with respect to the processing area 21.

[0145] Next, the irradiation area 22 moves from one side in the X direction to the other side within the processing area 21 at the end on the other side in the Y direction. Then, as the fourth process, the irradiation area 22 is moved along arrow d, and the laser is irradiated onto the processing area 21 once in sequence from the other side in the Y direction.

[0146] Figure 15 FIG. is a diagram showing an example of the irradiation area 22 in the fourth irradiation of the processing area 21 in Modification 2. As Figure 15 shown, when the irradiation area 22 moves along arrow d which represents the fourth process, a part of the irradiation area 22d in the processing area 21 overlaps with the irradiation area 22c in the third process. The center 23d of the irradiation area 22d in the fourth process is located between the center 23b of the irradiation area 22b in the second process and the center 23c of the irradiation area 22c in the third process. After that, such a change in the processing area 21 where the laser is irradiated is repeated. In addition, in Figure 15 for ease of observation, the irradiation areas 22a, 22b, 22c, and 22d are slightly offset with respect to the processing area 21.

[0147] The laser processing method of this modification also has the above-mentioned first process and second process in the same way as the laser processing method of Embodiment 1. Therefore, it is possible to suppress the deformation of the workpiece 20 caused by heat and to shorten the time required to form a plurality of recesses 30 in the workpiece 20. In addition, the laser processing method of this modification also has the above-mentioned third process and fourth process. Therefore, compared with the case where the third process and the fourth process are not provided, in each processing area 21, it is possible to reduce the area that overlaps with the irradiation area 22 irradiated immediately before in the irradiation area 22. Therefore, it is possible to further suppress the deformation of the workpiece 20 caused by heat.

[0148] In addition, the order of the processing areas 21 irradiated with the pulsed laser in the first process, the second process, the third process, and the fourth process may also be different from the arrangement order of the processing areas 21.

[0149] 3. Description of the Laser Processing System and Laser Processing Method of Embodiment 2

[0150] Next, the laser processing system 10 and the laser processing method of Embodiment 2 will be described. In addition, the same reference numerals are assigned to the structures having the same configuration as those described above, and the repeated description is omitted unless otherwise specified.

[0151] 3.1 Structure

[0152] Figure 16 is a schematic diagram showing a schematic configuration example of the laser processing apparatus 300 of the present embodiment. As Figure 16 shown, the difference between the laser processing apparatus 300 of the present embodiment and the laser processing apparatus 300 of Embodiment 1 is that it further includes a splitting optical system 380, high reflectors 331d, 331e, galvanometer scanners 363, 364, and an fθ lens 371.

[0153] The splitting optical system 380 is disposed on the optical path between the mask 335 and the high reflector 331b. The splitting optical system 380 includes, for example, a beam splitter 381 that reflects a part of the laser light from the mask 335 toward the high reflector 331d and transmits the remaining part. The transmitted light that has passed through the beam splitter 381 is reflected by the high reflector 331b toward the high reflector 331e. In this way, the splitting optical system 380 splits the laser light from the mask 335 into two laser lights La and Lb.

[0154] The structures of the high reflectors 331d and 331e are the same as those of the high reflectors 331a, 331b, and 331c, for example. The high reflector 331d reflects the laser light Lb from the beam splitter 381 toward the galvanometer scanner 363, and the high reflector 331e reflects the laser light La from the high reflector 331b toward the galvanometer scanner 361. The mirror 361b of the galvanometer scanner 361 reflects the laser light La from the high reflector 331e toward the mirror 362b, and the mirror 362b reflects the laser light La from the mirror 361b toward the fθ lens 370. That is, the galvanometer scanners 361 and 362 are provided for the laser light La. The fθ lens 370 condenses the laser light La irradiated from the galvanometer scanner 362 onto the surface of the workpiece 20 along the optical axis of the fθ lens 370.

[0155] The structures of the galvanometer scanners 363 and 364 are the same as those of the galvanometer scanner 361. The galvanometer scanners 363 and 364 include drive units 363a and 364a and mirrors 363b and 364b. The mirror 363b reflects the laser light Lb from the high reflector 331d toward the mirror 364b, and the mirror 364b reflects the laser light Lb from the mirror 363b toward the fθ lens 371. That is, the galvanometer scanners 363 and 364 are provided for the laser light Lb.

[0156] The galvanometer scanner 363 can change the optical path of the laser Lb through the mirror 363b to move the irradiation area 22 of the laser Lb in the X direction. The galvanometer scanner 364 can change the optical path of the laser Lb through the mirror 364b to move the irradiation area 22 of the laser Lb in the Y direction. That is, the galvanometer scanner 363 is the first moving part that can move the irradiation area 22 of the laser Lb in the X direction perpendicular to the irradiation direction of the laser Lb. In addition, the galvanometer scanner 364 is the second moving part that can move the irradiation area 22 of the laser Lb in the Y direction perpendicular to the irradiation direction of the laser Lb.

[0157] The structure of the fθ lens 371 is the same as that of the fθ lens 370, for example. The fθ lens 371 is arranged 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 Lb irradiated from the galvanometer scanner 364 onto the surface of the workpiece 20 along the optical axis of the fθ lens 371.

[0158] Figure 17 It is a diagram showing the surface of the workpiece 20 of the present embodiment. As Figure 17 shown, in the present embodiment, a plurality of processing areas 21 are arranged in two columns in the Y direction. The processing areas 21 in one column 26 are the areas processed by the irradiation of the laser La from the fθ lens 370, and the processing areas 21 in the other column 27 are the areas processed by the irradiation of the laser Lb from the fθ lens 371. The number of processing areas 21 in one column is the same as the number of processing areas 21 in the other column.

[0159] 3.2 Operation

[0160] Next, the operation of the laser processing system 10 and the laser processing method of the present embodiment will be described.

[0161] The laser processing processor 310 of this embodiment, similar to that of the first embodiment, controls the galvanometric scanners 361 and 362 to move the irradiation area 22 of the laser La from the fθ lens 370, and irradiates the laser La onto the processing areas 21 of one row 26. The laser La is irradiated onto different processing areas 21 for each pulse. In addition, the laser processing processor 310 controls the galvanometric scanners 363 and 364 in the same way as the galvanometric scanners 361 and 362, moves the irradiation area 22 of the laser Lb from the fθ lens 371, and irradiates the laser Lb onto the processing areas 21 of another row 27. The laser Lb is irradiated onto different processing areas 21 for each pulse. The control of the galvanometric scanners 361 and 362 is performed synchronously with the control of the galvanometric scanners 363 and 364. In addition, the lasers La and Lb are the lasers split by the splitting optical system 380. Therefore, the lasers La and Lb are simultaneously irradiated onto two of the plurality of processing areas 21.

[0162] 3.3 Functions and Effects

[0163] Similar to the laser processing method of Embodiment 1, the laser processing method of this embodiment includes: a first step of irradiating pulsed laser onto different processing areas 21 for each pulse; and a second step of irradiating pulsed laser onto different processing areas 21 for each pulse in such a way that a part of the irradiation area 22 of the pulsed laser in the first step overlaps. Therefore, according to the laser processing method of this embodiment, similar to the laser processing method of Embodiment 1, it is possible to suppress the deformation of the workpiece 20 caused by heat and shorten the time required to form a plurality of recesses 30 in the workpiece 20. In addition, in the laser processing method of this embodiment, in the first step and the second step, pulsed laser is simultaneously irradiated onto two of the plurality of processing areas 21. Therefore, according to the laser processing method of this embodiment, it is possible to further shorten the time required to form a plurality of recesses 30 in the workpiece 20.

[0164] In addition, the splitting optical system 380 may also split the laser from the mask 335 into three or more lasers. In this case, for example, two galvanometric scanners are provided for each of the split lasers. According to such a structure, in the first step and the second step, pulsed laser can be simultaneously irradiated onto three or more of the plurality of processing areas 21. In addition, it is preferable that the number of splits of the laser is less than or equal to half of the number of processing areas 21, and an integer multiple of the number of splits of the laser is the same as the number of processing areas 21.

[0165] In addition, at least one of the movement of the lasers La and Lb in the X direction and the movement of the irradiation area 22 in the Y direction may be performed by the stage 350.

[0166] As described above, the present invention has been described by taking the embodiments as examples, but the above embodiments can be appropriately changed. For example, in Embodiment 1, the outer shape of the laser beam irradiated onto the workpiece 20 is a rectangle elongated in the Y direction, but it may be a shape other than a rectangle, for example, it may also be a circle.

[0167] In addition, the arrangement direction of the plurality of workpieces 20 is not limited. For example, the plurality of workpieces 20 may also be arranged in the X direction. In addition, the plurality of workpieces 20 may not be arranged in a specified direction.

[0168] The above description is illustrative rather than restrictive. Therefore, it is obvious to those skilled in the art that the embodiments of the present disclosure can be changed without departing from the claims. In addition, it is obvious to those skilled in the art to use combinations of the embodiments of the present disclosure. Unless otherwise specified, the terms used in this specification and the claims should be interpreted as "non-limiting". For example, terms such as "comprising", "having", "including", and "possessing" should be interpreted as "not excluding the existence of elements other than those described". In addition, the modifier "one" should be interpreted as meaning "at least one" or "one or more". In addition, the term "at least one of A, B, and C" should be interpreted as "A", "B", "C", "A + B", "A + C", "B + C", or "A + B + C", and should also be interpreted as including combinations with things other than "A", "B", and "C".

Claims

1. A laser processing method, comprising: irradiating a plurality of processing areas separated from each other on a surface of a workpiece with a pulsed laser to form a plurality of recesses, wherein: The laser processing method comprises: The first step is to irradiate the pulse laser onto different processing areas according to each pulse; as well as In the second step, the pulse laser is irradiated onto the different processing area for each pulse so as to overlap a part of the irradiation area of ​​the pulse laser in the first step.

2. The laser processing method according to claim 1, wherein: The plurality of processing areas are arranged along a specified direction, In the first step, the pulse laser is sequentially irradiated onto the processing area from one side of the predetermined direction. In the second step, the processing region is irradiated with the pulse laser in sequence from the other side in the predetermined direction.

3. The laser processing method according to claim 1, wherein: The plurality of processing areas are arranged along a specified direction, In the first step and the second step, the pulse laser is irradiated onto the processing area in sequence from one side in the predetermined direction.

4. The laser processing method according to claim 1, wherein: The laser processing method further comprises: a third step between the first step and the second step, in which the pulse laser is irradiated onto a different processing area for each pulse; and In a fourth step after the second step, in the fourth step, the pulse laser is irradiated onto different processing areas according to each pulse, In each of the processing areas, the center of the irradiation area in the third process is located on the side opposite to the center of the irradiation area in the first process than the center of the irradiation area in the second process, and the center of the irradiation area in the fourth process is located between the center of the irradiation area in the third process and the center of the irradiation area in the second process.

5. The laser processing method according to claim 4, wherein: The plurality of processing areas are arranged along a specified direction, In the first step and the second step, the pulse laser is sequentially irradiated onto the processing area from one side of the predetermined direction. In the third step and the fourth step, the pulse laser is irradiated onto the processing region in order from the other side of the predetermined direction.

6. The laser processing method according to claim 1, wherein: In the first step and the second step, two or more of the plurality of processing regions are irradiated with the pulse laser light at the same time.

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

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

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

10. The laser processing method according to claim 1, wherein: The shape of the pulse laser is rectangular. The irradiation region in the second step is a region obtained by moving the irradiation region in the first step in the short-side direction of the outer shape of the pulse laser.

11. The laser processing method according to claim 10, wherein: The width of the processing region in a 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 of the pulse laser in the short side direction.

12. A laser processing system for forming a plurality of recessed portions by irradiating a plurality of processing regions separated from each other on a surface of a workpiece with pulsed laser light, wherein: The laser processing system comprises: a gas laser device that emits the pulse laser; a moving portion capable of moving an irradiation area of ​​the pulse laser on the surface; and processor, The processor performs: A first control is to control the moving part and the gas laser device so as to irradiate the pulse laser to different processing areas for each pulse; as well as The second control controls the moving part and the gas laser device so as to irradiate the pulse laser onto the different processing area for each pulse so as to overlap a part of the irradiation area of ​​the pulse laser in the first control.

13. The laser processing system according to claim 12, wherein: The mobile unit comprises: a first moving portion capable of moving the irradiation area in a first direction; and The second moving part is capable of moving the irradiation area in a second direction perpendicular to the first direction.

14. The laser processing system according to claim 13, wherein: The first moving part is a Galvano scanner that changes the optical path of the pulse laser along the first direction. The processor controls the Galvano scanner in the second control so that the optical path of the pulsed laser light is located closer to the first direction than the optical path in the first control.

15. The laser processing system according to claim 13, wherein: The first moving part is a mounting table including a worktable that supports the workpiece and is movable in the first direction. The processor controls the mounting table in the second control so that the workpiece is located closer to the first direction side than the workpiece in the first control.

16. The laser processing system according to claim 13, wherein: The plurality of processing areas are arranged along the second direction, The second moving unit is a Galvano scanner that changes the optical path of the pulse laser along the second direction.

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