Patent Application
20250199416
The present application claims the benefit of Japanese Patent Application No. 2023-212513, filed on Dec. 15, 2023, the entire contents of which are hereby incorporated by reference.
The present disclosure relates to a laser processing system and a laser processing method.
In recent years, a semiconductor exposure apparatus is required to improve the resolution thereof as semiconductor integrated circuits are increasingly miniaturized and highly integrated. To this end, reduction in the wavelength of light emitted from a light source for exposure is underway. For example, a KrF excimer laser apparatus, which outputs laser light having a wavelength of about 246.0 nm, and an ArF excimer laser apparatus, which outputs laser light having a wavelength of about 193.4 nm, are used as a gas laser apparatus for exposure.
The light from spontaneously oscillating KrF and ArF excimer laser apparatuses has a wide spectral linewidth ranging from 350 pm to 400 pm. A projection lens made of a material that transmits ultraviolet light, such as KrF and ArF laser light, therefore produces chromatic aberrations in some cases. As a result, the resolution of the projection lens may decrease. To avoid the decrease in the resolution, the spectral linewidth of the laser light output from the gas laser apparatus needs to be narrow enough to make the chromatic aberrations negligible. To this end, a line narrowing module (LNM) including a line narrowing element (such as etalon or grating) is provided in some cases in a laser resonator of the gas laser apparatus to narrow the spectral linewidth. A gas laser apparatus providing a narrowed spectral linewidth is hereinafter referred to as a narrowed-line gas laser apparatus.
[PTL 1] JP-A-2004-230441
[PTL 2] U.S. Patent application Publication No. 2002/0064345
A laser processing system according to an aspect of the present disclosure may be a laser processing system for forming plural recesses by radiating pulse laser light to plural processing receiving regions separate from each other in a first direction on a surface of a workpiece, the system including a gas laser apparatus configured to output the pulse laser light, a mover configured to move a radiation receiving region on the surface that is irradiated with the pulse laser light in the first direction, and a first galvanometric scanner configured to change an optical path of the pulse laser light to move the radiation receiving region in the first direction, the mover moving the radiation receiving region in such a way that the moved radiation receiving region overlaps with a part of the radiation receiving region irradiated with the pulse laser light immediately before, and the first galvanometric scanner moving the radiation receiving region in such a way that the moved radiation receiving region is located within the processing receiving region different from the processing receiving region irradiated with the pulse laser light immediately before.
A laser processing method according to another aspect of the present disclosure may be a laser processing method for forming plural recesses by radiating pulse laser light to plural processing receiving regions separate from each other in a first direction on a surface of a workpiece, the method including a first process of causing a mover configured to move in the first direction a radiation receiving region on the surface that is irradiated with the pulse laser light to move the radiation receiving region in such a way that the moved radiation receiving region overlaps with a part of the radiation receiving region irradiated with the pulse laser light immediately before within the processing receiving region irradiated with the pulse laser light immediately before, and a second process of causing a first galvanometric scanner configured to change an optical path of the pulse laser light to move the radiation receiving region in the first direction to move the radiation receiving region in such a way that the moved radiation receiving region is located within the processing receiving region different from the processing receiving region irradiated with the pulse laser light immediately before.
Embodiments of the present disclosure will be described below only by way of example with reference to the accompanying drawings.
Embodiments of the present disclosure will be described below in detail with reference to the drawings. The embodiments described below show some examples of the present disclosure and are not intended to limit the content of the present disclosure. Furthermore, all configurations and operations described in the embodiments are not necessarily essential as configurations and operations in the present disclosure. The same component has the same reference character, and no redundant description of the same component will be made.
A laser processing system and a laser processing method according to Comparative Example will be described. Comparative Example in the present disclosure is a form that the applicant is aware of as known only by the applicant, and is not a publicly known example that the applicant is self-aware of.
The gas laser apparatus 100 according to the present example is an ArF excimer laser apparatus using a mixture gas containing argon (Ar), fluorine (F2), and neon (Ne). The gas laser apparatus 100 outputs laser light having a center wavelength of about 193.4 nm. Note that the gas laser apparatus 100 may instead be a gas laser apparatus other than the ArF excimer laser apparatus, for example, a KrF excimer laser apparatus using a mixture gas containing krypton (Kr), F2, and Ne. In this case, the gas laser apparatus 100 outputs laser light having a center wavelength of about 246.0 nm. The mixture gas containing Ar, F2, and Ne and the mixture gas containing Kr, F2, and Ne, the constituent elements in each of the mixture gases forming a laser medium, are each called a laser gas in some cases.
The gas laser apparatus 100 primarily includes an enclosure 110, a laser oscillator 130, a monitor module 150, a shutter 170, and a laser processor 190, the latter four components of which are arranged in the internal space of the enclosure 110.
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.
The laser chamber 131 has an internal space where the laser medium in the laser gas described above is excited to generate light. The light travels to windows 139a and 139b, which will be described later. The laser gas is supplied to the internal space of the laser chamber 131 from a laser gas supply source that is not shown via a pipe that is not shown. The laser gas in the laser chamber 131 is caused to flow through a halogen filter that removes the F2 gas from the laser gas and otherwise processed, and the removed F2 gas is exhausted by an exhaust pump that is not shown into the enclosure 110 through a pipe that is not shown.
A pair of electrodes 133a and 133b are arranged so as to face each other in the internal space of the laser chamber 131, and the longitudinal direction of the electrodes 133a and 133b extends along the traveling direction of the light. The electrodes 133a and 133b are discharge electrodes that produce glow discharge to excite the laser medium. In the present example, the electrode 133a is the cathode, and the electrode 133b is the anode.
The electrode 133a is supported by an electrical insulator 135. The electrical insulator 135 closes an opening formed in the laser chamber 131. Electrical conductors that are not shown are embedded in the electrical insulator 135, and the electrical conductors apply 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 via wiring that is not shown.
The charger 141 is a DC power supply that supplies a predetermined voltage to charge a charging capacitor that is not shown but is provided in the pulse power module 143. The pulse power module 143 includes a switch 143a controlled by the laser processor 190. When the switch 143a is changed from the turned-off state to the turned-on state, the pulse power module 143 generates a high pulse voltage from the electrical energy held in the charger 141 and applies the high voltage to the space between the electrodes 133a and 133b.
When the high voltage is applied to the space between the electrodes 133a and 133b, discharge occurs between the electrodes 133a and 133b. The energy of the discharge excites the laser medium in the laser chamber 131, and the excited laser medium emits light when transitioning to the ground state.
The laser chamber 131 is provided with the windows 139a and 139b. The window 139a is located at one end of the laser chamber 131 in the traveling direction of the laser light, and the window 139b is located at the other end in the traveling direction, so that the windows 139a and 139b sandwich the space between the electrodes 133a and 133b. The windows 139a and 139b each incline with respect to the traveling direction of the laser light by Brewster's angle, and therefore suppress reflection of a P-polarized component of the laser light. The laser light as a result of laser oscillation that will be described later exits out of the laser chamber 131 via the windows 139a and 139b. Since the high pulse voltage is applied to the space between the electrodes 133a and 133b by the pulse power module 143 as described above, the laser light is pulse laser light.
The rear mirror 145 is disposed in the internal space of an enclosure 145a connected to the one end of the laser chamber 131, and reflects the laser light output via the window 139a back 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 of the laser chamber 131, transmits part of the laser light output via the window 139b, and reflects the other part of the laser light back into the internal space of the laser chamber 131. The rear mirror 145 and the output coupling mirror 147 thus constitute a Fabry-Perot laser resonator, and the laser chamber 131 is disposed in the optical path of the laser resonator.
The monitor module 150 is disposed in the optical path of the laser light output via the output coupling mirror 147. The monitor module 150 includes, for example, an enclosure 151, a beam splitter 153, and a photosensor 155, the latter two components of which are disposed in the internal space of the enclosure 151. An opening is formed in the enclosure 151, and the internal space of the enclosure 151 communicates with the internal space of the optical path tube 147a via the opening.
The beam splitter 153 transmits part of the laser light output via 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 energy E of the laser light incident on the light receiving surface. The photosensor 155 outputs a signal representing the measured energy E to the laser processor 190.
The laser processor 190 in the present disclosure is a processing apparatus including a storage 190a, which stores a control program, and a CPU (central processing unit) 190b, which executes the control program. The laser processor 190 is particularly configured or programmed to perform a variety of types of processing described in the present disclosure. The laser processor 190 controls the entire gas laser apparatus 100.
The laser processor 190 transmits and receives a variety of signals to and from a laser processing processor 310 of the laser processing apparatus 300. For example, the laser processor 190 receives from the laser processing processor 310 a signal representing a light emission trigger Tr, which will be described later, target energy Et, which will be described later, and other pieces of information. The laser processor 190 controls a charging voltage applied to the charger 141 based on the energy E received from the photosensor 155 and the target energy Et received from the laser processing processor 310. Controlling the charging voltage controls the energy of the laser light. The laser processor 190 also transmits a command signal that turns on or off the switch 143a to the pulse power module 143. Furthermore, the laser processor 190 is electrically connected to the shutter 170 and controls opening and closing of the shutter 170.
The laser processor 190 closes the shutter 170 until a difference ΔE between the energy E received from the monitor module 150 and the target energy Et received from the laser processing processor 310 falls within an allowable range. When the difference ΔE falls within the allowable range, the laser processor 190 transmits a reception preparation completion signal indicating that the laser processor 190 is ready to receive the light emission trigger Tr to the laser processing processor 310. Upon reception of the reception preparation completion signal, the laser processing processor 310 transmits a signal representing the light emission trigger Tr to the laser processor 190, and upon reception of the signal representing the light emission trigger Tr, the laser processor 190 opens the shutter 170. The light emission trigger Tr is a timing signal or an external trigger that is specified by a predetermined repetition frequency f of the laser light and a predetermined number of pulses P, and in response to the light emission trigger Tr, the laser processing processor 310 causes the laser oscillator 130 to undergo laser oscillation. The repetition frequency f of the laser light is, for example, higher than or equal to 1 kHz but lower than or equal to 10 kHz.
The shutter 170 is disposed in the optical path of the laser light having passed through the beam splitter 153 of the monitor module 150 and having passed through an opening of the enclosure 151 that is formed on the side thereof opposite from the side to which the optical path tube 147a is connected. The shutter 170 is also disposed in the internal space of an optical path tube 171, and the optical path tube 171 is connected to the enclosure 151 so as to surround the opening mentioned above, and communicates with the enclosure 151. The optical path tube 171 further communicates with the laser processing apparatus 300 via the above-mentioned opening of the enclosure 110 and the optical path tube PO.
The internal spaces of the optical path tubes 171 and 147a, and the internal spaces of the enclosures 151 and 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 that is not shown into the internal spaces of the optical path tubes 171 and 147a and the internal spaces of the enclosures 151 and 145a through a pipe that is not shown.
The laser processing apparatus 300 includes the laser processing processor 310, an optical system 330, a stage 350, an enclosure 355, and a frame 357 as primary components. The optical system 330 and the stage 350 are disposed in the internal space of the enclosure 355. The enclosure 355 is fixed to the frame 357. The optical path tube PO is connected to the enclosure 355, and the internal space of the enclosure 355 communicates with the internal space of the optical path tube PO via an opening formed in the enclosure 355, so that the laser light having passed through the region from which the shutter 170 has been retracted enters the enclosure 355.
The laser processing processor 310 is a processing apparatus including a storage 310a, which stores a control program, and a CPU 310b, which executes the control program. The laser processing processor 310 is particularly configured or programmed to perform a variety of types of processing described in the present disclosure. The laser processing processor 310 controls the entire laser processing apparatus 300.
The optical system 330 includes highly reflective mirrors 331a, 331b, and 331c, an attenuator 332, a fly-eye lens 333, a condenser lens 334, a mask 335, and a projection optical system 336. Each of the components of the optical system 330 is fixed to a holder that is not shown, and is disposed at a predetermined position in the enclosure 355.
The highly reflective mirrors 331a, 331b, and 331c are each formed, for example, of a transparent substrate made of synthetic quartz or calcium fluoride and having a surface coated with a reflective film that reflects the laser light at high reflectance. The highly reflective mirror 331a reflects the laser light incident from the gas laser apparatus 100 toward the attenuator 332. The highly reflective mirror 331b reflects the laser light from the attenuator 332 toward the highly reflective mirror 331c. The highly reflective mirror 331c reflects the laser light from the highly reflective mirror 331b toward the fly-eye lens 333.
The attenuator 332 is disposed in the optical path between the highly reflective mirror 331a and the highly reflective mirror 331b. The attenuator 332 includes, for example, rotary stages 332a and 332b, and partially reflective mirrors 332c and 332d fixed to the rotary stages 332a and 332b, respectively. Each of the rotary stages 332a and 332b is electrically connected to the laser processing processor 310, and rotates around the Y-axis in accordance with a control signal from the laser processing processor 310. When the rotary stages 332a and 332b rotate, the partially reflective mirrors 332c and 332d also rotate, respectively. The partially reflective mirrors 332c and 332d are optical elements having transmittance that changes in accordance with the angles of incidence of the laser light incident on the partially reflective mirrors 332c and 332d. The angles of rotation of the partially reflective mirrors 332c and 332d around the Y-axis are so adjusted by the rotation of the rotary stages 332a and 332b that the angles of incidence of the laser light incident on the partially reflective mirrors 332c and 332d coincide with each other and the transmittance of the partially reflective mirrors 332c and 332d have desired transmittance. The laser light from the highly reflective mirror 331a is therefore attenuated so as to have desired energy and passes through the attenuator 332.
The fly-eye lens 333 is a lens including plural lenses juxtaposed, for example, in a honeycomb shape, and is also called an optical integration lens. The fly-eye lens 333 is so disposed that the light-exiting-side focal plane of the fly-eye lens 333 coincides with the light-incident-side focal plane of the condenser lens 334, so that the fly-eye lens 333 outputs the laser light in such a way that the laser light incident on the condenser lens 334 has a uniform energy density.
The condenser lens 334 is a lens that collects the laser light output from the fly-eye lens 333, and is so disposed that the light-exiting-side focal plane of the condenser lens 334 coincides with the upper surface of the mask 335.
The mask 335 is, for example, a plate-shaped member that has a transmission hole through which part of the laser light passes and blocks the other part of the laser light. In the present example, the transmission hole is formed of a rectangular hole, and the laser light having passed through the transmission hole has a rectangular outer shape elongated in the Y direction.
The projection optical system 336 includes, for example, a collimator lens 336a and a light collecting lens 336b. The collimator lens 336a outputs the laser light from the mask 335 as parallelized light. The light collecting lens 336b collects the laser light from the collimator lens 336a and brings the collected laser light into focus at the surface of the workpiece 20.
The stage 350 is disposed at the bottom surface of the enclosure 355 and includes a table 351. The stage 350 can move the table 351 in the X, Y, and Z directions in response to a control signal from the laser processing processor 310, and adjust the position of the table 351 through the movement.
The table 351 supports the workpiece 20. The principal surface of the table 351 is substantially perpendicular to the Z-axis and substantially extends along the XY plane. The front and rear surfaces of the workpiece 20 are therefore substantially perpendicular to the Z-axis and located substantially along the XY plane. The thus configured stage 350 can move the workpiece 20 via the table 351 to adjust the position of the workpiece 20 in such a way that the workpiece 20 is irradiated at a desired position with plural pulses of the laser light output from the optical system 330. That is, the stage 350 is a mover that can move a radiation receiving region on the surface of the workpiece 20 that is irradiated with the laser light in the X and Y directions perpendicular to the direction in which the laser light is radiated.
The workpiece 20 is a target object that undergoes laser processing through the radiation of the laser light. The workpiece 20 may, for example, be a light-transmissive, plate-shaped member that eventually forms an optical waveguide substrate. Examples of the material of which the plate-shaped member is made may include polyimide resin and polynorbornene resin.
An inert gas constantly flows in the internal space of the enclosure 355 during the period for which the laser processing system 10 is in operation. The inert gas is, for example, a nitrogen gas. The enclosure 355 is provided with a suction port which is not shown but via which the inert gas is sucked into the enclosure 355, and a discharge port which is not shown but via which the inert gas is discharged out of the enclosure 355. An intake pipe and a discharge pipe that are not shown are connected to the suction port and the discharge port, respectively. A gas supply source that is not shown but supplies the inert gas is connected to the suction port via a pipe. The inert gas supplied via the suction port also flows through the optical path pipe PO, which communicates with the enclosure 355.
The operation of the laser processing system 10 and the laser processing method according to Comparative Example will next be described.
In the gas laser apparatus 100, before the gas laser apparatus 100 outputs the laser light, the internal spaces of the optical path tubes 147a, 171, and PO and the internal spaces of the enclosures 145a and 151 are filled with the purge gas from the purge gas supply source, which is not shown. The laser gas is supplied from the laser gas supply source, which is not shown, into the internal space of the laser chamber 131. In the laser processing apparatus 300, the inert gas such as a nitrogen gas flows in the internal space of the enclosure 355.
In the laser processing apparatus 300, the workpiece 20 is supported by the upper surface of the table 351. The laser processing processor 310 sets the following coordinates to the stage 350: the coordinates X, Y, and Z of an initial radiation receiving position to which the laser light is radiated to form a processing receiving portion. The stage 350 thus moves the table 351 along with the workpiece 20 to the set initial radiation receiving position. Note that the radiation receiving position is the position of the center of the radiation receiving region irradiated with the laser light.
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 apparatus 100 in such a way that the laser light to be radiated to the workpiece 20 has a desired fluence F necessary for the laser processing. The fluence F is defined as the value as a result of division of the energy of the laser light by the cross-sectional area of the laser light that is perpendicular to the optical axis of the laser light.
The laser processor 190 closes the shutter 170 and drives the charger 141. The laser processor 190 turns on the switch 143a of the pulse power module 143. The pulse power module 143 thus applies the high pulse voltage derived from the electrical energy held in the charger 141 to the space between the electrodes 133a and 133b. The high voltage causes discharge to occur between the electrodes 133a and 133b, and the laser medium contained in the laser gas between the electrodes 133a and 133b is excited, and when the laser medium returns to the ground state, the laser medium emits light. The light resonates between the rear mirror 145 and the output coupling mirror 147, and the light is amplified whenever passing through the discharge space in the internal space of the laser chamber 131, resulting in laser oscillation. Part of the laser light then passes as the pulse laser light through the output coupling mirror 147 and travels to the beam splitter 153.
Part of the laser light having traveled to the beam splitter 153 is reflected off the beam splitter 153 and received by the photosensor 155. The photosensor 155 measures the energy E of the received laser light and outputs the signal representing the measured energy E to the laser processor 190. The laser processor 190 controls the charging voltage in such a way that the difference ΔE between the energy E and the target energy Et falls within the allowable range, and after the difference ΔE falls within the allowable range, the laser processor 190 transmits the reception preparation completion signal, which indicates that the laser processor 190 is ready to receive the light emission trigger Tr, to the laser processing processor 310.
Upon reception of the reception preparation completion signal, the laser processing processor 310 transmits the light emission trigger Tr to the laser processor 190. When the laser processor 190 opens the shutter 170 in synchronization with the reception of the light emission trigger Tr, the laser light having passed through the region from which the shutter 170 has been retracted enters the laser processing apparatus 300. The laser light is, for example, the pulse laser light having the center wavelength of 193.4 nm.
The laser light having entered the laser processing apparatus 300 is radiated to the mask 335 via the highly reflective mirror 331a, the attenuator 332, the highly reflective mirrors 331b and 331c, the fly-eye lens 333, and the condenser lens 334. At this point in time, the laser light is radiated onto the mask 335 in the form of Koehler illumination. At the mask 335, part of the laser light passes through the transmission hole, which shapes the laser light in a rectangular outer shape elongated in the Y direction, and the other part of the laser light is blocked. The laser light having passed through the mask 335 is parallelized by the collimator lens 336a of the projection optical system 336, and is focused at the surface of the workpiece 20 by the light collecting lens 336b.
The laser light is radiated to the workpiece 20 in accordance with the light emission trigger Tr specified by the repetition frequency f and the number of pulses P both required for the laser processing. The laser light radiation causes ablation in the vicinity of the surface of the workpiece 20, which produces defects. The workpiece 20 is thus processed at the processing receiving portion, so that a recess is formed. In the present example, plural processing receiving portions separate from each other are processed, so that plural recesses are formed.
The processing receiving regions 21 in the present example each have a substantially quadrangular outer shape having opposite sides facing each other in the X direction and opposite sides facing each other in the Y direction. The width of each of the processing receiving regions 21 in the Y direction is approximately equal to the width of a radiation receiving region 22 in the Y direction, which is irradiated with the laser light in one pulse, and the width of each of the processing receiving regions 21 in the X direction is greater than the width of the radiation receiving region 22 in the X direction, approximately twice the width of the latter. Radiating the laser light multiple times therefore causes the entirety of each of the processing receiving regions 21 to be irradiated with the laser light. In
Radiating the laser light to the radiation receiving region 22a forms another recess 25 in the workpiece 20, as shown in
The workpiece 20 is then so moved by the stage 350 that the radiation receiving region 22 abuts the edge of another processing receiving region 21 on one side in the X direction, and the radiation of the laser light and the movement of the radiation receiving region 22 described above are repeated. In the present example, the processing receiving region 21 irradiated with the laser light is changed to another along the line indicated by an arrow a, an arrow b, and an arrow c in this order shown in
The travel distance of the radiation receiving region 22 between different processing receiving regions 21 is longer than the travel distance of the radiation receiving region 22 within a single processing receiving region 21. It therefore takes a long period to move the radiation receiving region 22 between the processing receiving regions 21, resulting in a long processing period.
To address the problem described above, a laser processing system 10 and a laser processing method that can shorten the processing period will be described by way of example in the following embodiments.
The laser processing system 10 and the laser processing method according to a first embodiment will be described. The same components as those described above have the same reference characters, and duplicate description of the same components will be omitted unless otherwise particularly described.
The fly-eye lens 333, the condenser lens 334, and the mask 335 are arranged in the optical path between the attenuator 332 and the highly reflective mirror 331b.
The galvanometric scanner 361 includes a driver 361a and a mirror 361b, which is attached to a swing shaft of the driver 361a and is swingable around the swing shaft. The galvanometric scanner 362 has a configuration that is the same as the configuration of the galvanometric scanner 361, and includes a driver 362a and a mirror 362b, which is attached to a swing shaft of the driver 362a and is swingable around the swing shaft.
The drivers 361a and 362a are, for example, motors, and are electrically connected to the laser processing processor 310. The swing speeds and swing angles of the swing shafts of the drivers 361a and 362a are controlled by control signals from the laser processing processor 310. The swing shaft of the driver 361a is perpendicular to the swing shaft of the driver 362a.
The mirror 361b reflects the laser light from the highly reflective mirror 331b toward the mirror 362b, and the mirror 362b reflects the laser light 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 respective swing shafts of the drivers 361a and 362a. The orientations of the mirrors 361b and 362b may be adjusted in synchronization with each other. The speeds of the swinging mirrors 361b and 362b are adjusted by the swing speeds of the swinging swing shafts of the drivers 361a and 362a.
The galvanometric scanner 361 can change the optical path of the laser light along the X direction with the aid of the mirror 361b to move the radiation receiving region 22 irradiated with the laser light in the X direction. The galvanometric scanner 362 can change the optical path of the laser light along the Y direction with the aid of the mirror 362b to move the radiation receiving region 22 irradiated with the laser light in the Y direction. That is, the galvanometric scanner 361 is a mover that can move the radiation receiving region 22 irradiated with the laser light in the X direction perpendicular to the laser light radiation direction. The galvanometric scanner 362 is a mover that can move the radiation receiving region 22 irradiated with the laser light in the Y direction perpendicular to the laser light radiation direction. The minimum travel distance of the radiation receiving region 22 that can be adjusted by the galvanometric scanner 361 is approximately equal to the minimum travel distance of the radiation receiving region 22 that can be adjusted by the galvanometric scanner 362. It is preferable that the minimum travel distance of the radiation receiving region 22 in the X direction that can be adjusted by the stage 350 is shorter than the minimum travel distance of the radiation receiving region 22 that can be adjusted by the galvanometric scanner 361. It is further preferable that the minimum travel distance of the radiation receiving region 22 in the Y direction that can be adjusted by the stage 350 is shorter than the minimum travel distance of the radiation receiving region 22 that can be adjusted by the galvanometric scanner 362. Note that the relationship described above between the former and latter minimum travel distance in terms of magnitude is not limited to a specific relationship.
The fθ lens 370 is fixed to a holder that is not shown in the optical path between the mirror 362b and the workpiece 20, and is disposed at a predetermined position in the enclosure 355. The optical axis of the fθ lens 370 extends along the Z direction. The fθ lens 370 collects the laser light radiated from the galvanometric scanner 362 and brings the collected laser light into focus at the surface of the workpiece 20 along the optical axis of the fθ lens 370.
The operation of the laser processing processor 310 in the present embodiment will next be described.
In the starting state shown in
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 310a. The parameters in the present embodiment include the number nmax of processing receiving regions 21, the maximum number of times mmax each of the processing receiving regions 21 is irradiated with the laser light, the number n, and the coordinates of each of the processing receiving regions 21.
The processing receiving regions 21 are numbered from 1 to nmax. The number n is the number of the processing receiving regions 21, and the initial value of n is one. In the present embodiment, the number successively increases along the line indicated by the arrow a, the arrow b, and the arrow c in this order shown in
This step is the step of moving the table 351 of the stage 350. In this step, the laser processing processor 310 controls the stage 350 in such a way that the table 351 moves at a constant speed from the other side to the one side in the X direction. The control described above continues until step SP16. After starting the control, the laser processing processor 310 proceeds to step SP13 in the control flowchart.
This step is the step of moving a radiation receiving position irradiated with the laser light. In this step, the laser processing processor 310 controls the galvanometric scanners 361 and 362 in such a way that the coordinates of the radiation receiving position become the coordinates of the processing receiving region 21 having the number n. The coordinates of the radiation receiving position are the XY coordinates of the center 23 of the radiation receiving region 22 irradiated with the laser light. After moving the radiation receiving position, the laser processing processor 310 proceeds to step SP14 in the control flowchart.
This step is the step of irradiating the workpiece 20 with the laser light for a predetermined period. In this step, the laser processing processor 310 transmits the light emission trigger Tr to the laser processor 190 to cause the laser processor 190 to open the shutter 170. The laser light thus enters the laser processing apparatus 300 from the gas laser apparatus 100. The laser light having entered the laser processing apparatus 300 sequentially travels via the highly reflective mirror 331a, the attenuator 332, the condenser lens 334 the mask 335, the highly reflective mirror 331b, the mirror 361b, the mirror 362b, and the fθ lens 370, and is radiated to the workpiece 20. The workpiece 20 is processed by the laser light radiated thereto. During this step, since the table 351 moves at a constant speed from the other side to the one side in the X direction, the workpiece 20 also moves at the constant speed from the other side to the one side in the X direction. The radiation receiving region 22 therefore moves toward the other side in the X direction as the time elapses. In the present embodiment, the period for which the laser light is radiated is so adjusted that the radiation receiving region 22 overlaps a part of the radiation receiving region 22 irradiated with the laser light immediately before, and that the mmax-th radiation receiving region 22 abuts the edge of the processing receiving region 21 on the other side in the X direction. The stage 350 therefore moves the radiation receiving region 22 in such a way that the moved radiation receiving region 22 overlaps with a part of the radiation receiving region 22 irradiated with the laser light immediately before. The movement described above is a first process of causing the stage 350 capable of moving the radiation receiving region 22 in the X direction to move the radiation receiving region 22 so as to overlap with a part of the radiation receiving region 22 irradiated with the laser light immediately before, and the first process and the laser light radiation are repeated. Radiating the laser light mmax times causes the entire processing receiving region 21 to be irradiated with the laser light, and the recess 30 is formed in the processing receiving region 21. After performing the mmax-th laser light radiation, the laser processing processor 310 proceeds to step SP15 in the control flowchart.
This step is the step of incrementing the number n by one. In this step, the laser processing processor 310 rewrites the number n to n+1 and proceeds to step SP16 in the control flowchart.
This step is the step of selecting the following step from different steps in accordance with the number n. In this step, the laser processing processor 310 returns to step SP13 in the control flowchart when the number n is smaller than or equal to nmax, and proceeds to step SP17 in the control flowchart when the number n is greater than nmax. When there is a processing receiving region 21 that has not been irradiated with the laser light, the galvanometric scanners 361 and 362 move the radiation receiving region 22 in such a way that the moved radiation receiving region 22 is located within a processing receiving region 21 different from the processing receiving region 21 irradiated with the laser light immediately before. The movement of the radiation receiving region 22 between the processing receiving regions 21 is performed along the line indicated by the arrow a, the arrow b, and the arrow c in this order shown in
This step is the step of stopping the movement of the table 351 of the stage 350. This step is carried out when the number n is greater than nmax in step SP15, and is carried out after all the processing receiving regions 21 are irradiated with the laser light. In this step, the laser processing processor 310 controls the stage 350 to stop the movement of the table 351. The recesses 30 are formed in all the processing receiving regions 21, and the processing of the workpiece 20 is completed.
The laser processing method according to the present embodiment includes the first and second processes. In the first process, the stage 350 capable of moving the radiation receiving region 22 in the X direction moves the radiation receiving region 22 so as to overlap with a part of the radiation receiving region 22 irradiated with the pulse laser light immediately before. In the second process, the galvanometric scanner 361 capable of moving the radiation receiving region 22 in the X direction moves the radiation receiving region 22 in such a way that the moved radiation receiving region 22 is located within a processing receiving region 21 different from the processing receiving region 21 irradiated with the pulse laser light immediately before. In the laser processing system 10 according to the present embodiment, the stage 350 moves the radiation receiving region 22 in such a way that the moved radiation receiving region 22 overlaps with a part of the radiation receiving region 22 irradiated with the pulse laser light immediately before. The galvanometric scanner 361 moves the radiation receiving region 22 in such a way that the moved radiation receiving region 22 is located within a processing receiving region 21 different from the processing receiving region 21 irradiated with the pulse laser light immediately before. The galvanometric scanner 361, which changes the optical path of the pulse laser light to move the radiation receiving region 22, can reduce the period required to move the radiation receiving region 22 as compared with the stage 350, which moves the table 351, which supports the workpiece 20, to move the radiation receiving region 22. The laser processing method and the laser processing system 10 according to the present embodiment can therefore shorten the processing period as compared with the case where the stage 350 moves the radiation receiving region 22 between different processing receiving regions 21.
Furthermore, the laser processing method and the laser processing system 10 according to the present embodiment allow the galvanometric scanner 361 to move the radiation receiving region 22 between the processing receiving regions 21 separate from each other in the X direction even when the workpiece 20 is moved by the stage 350 in the X direction.
In the laser processing method and the laser processing system 10 according to the present embodiment, the two processing receiving regions 21 in each of the sets 26, which each include processing receiving regions 21, are separate from each other in the X direction. The direction in which the radiation receiving region 22 moves in each of the processing receiving regions 21 is the direction from one side toward the other side in the X direction. The inclining surface 31 of the recess 30 formed in each of the processing receiving regions 21 therefore inclines so as to approach the surface of the workpiece 20 as extending from the one side toward the other side in the X direction. The laser processing method and the laser processing system 10 according to the present embodiment are therefore particularly useful to manufacture an optical waveguide substrate in which micromirrors inclining as described above are arranged in the X direction.
The laser processing system 10 according to the present embodiment further includes the galvanometric scanner 362, which can move the radiation receiving region 22 in the Y direction perpendicular to the X direction. Therefore, even when the stage 350 moves the workpiece 20 in the X direction, the galvanometric scanners 361 and 362 can move the radiation receiving region 22 between the processing receiving regions 21 located at positions different from each other in the Y direction.
In the laser processing method according to the present embodiment, the stage 350 moves the workpiece 20 at a constant speed in the X direction until the processing of all the processing receiving regions 21 is completed. In the second process described above, however, the stage 350 may not move the workpiece 20 in the X direction. Furthermore, the order of processing receiving regions 21 to be irradiated with the laser light is not limited to a specific order.
The laser processing system 10 and the laser processing method according to a second embodiment will next be described. The same components as those described above have the same reference characters, and duplicate description of the same components will be omitted unless otherwise particularly described.
The galvanometric scanner 363 is disposed in the optical path between the mask 335 and the galvanometric scanner 361, and located upstream from the galvanometric scanner 361 in the traveling direction of the laser light. The galvanometric scanner 363 includes a driver 363a and a mirror 363b, which is attached to a swing shaft of the driver 363a and is swingable around the swing shaft. The driver 363a can change the orientation of the mirror 363b as the driver 361a of the galvanometric scanner 361. The mirror 363b reflects the laser light from the mask 335 toward the mirror 361b of galvanometric scanner 361. The mirror 361b reflects the laser light from the mirror 363b toward the mirror 362b of the galvanometric scanner 362, and the mirror 362b reflects the laser light from the mirror 361b toward the fθ lens 370. The fθ lens 370 collects the laser light radiated from the galvanometric scanner 362 and brings the collected laser light into focus at the surface of the workpiece 20 along the optical axis of the fθ lens 370.
The galvanometric scanner 363 can change the optical path of the laser light along the X direction with the aid of the mirror 363b to move the radiation receiving region 22 irradiated with the laser light in the X direction. That is, the galvanometric scanner 363 is a mover that can move the radiation receiving region 22 irradiated with the laser light in the X direction. It is preferable that the minimum travel distance of the radiation receiving region 22 that can be adjusted by the galvanometric scanner 363 is shorter than the minimum travel distance of the radiation receiving region 22 that can be adjusted by the galvanometric scanner 361.
The operation of the laser processing processor 310 in the present embodiment will next be described.
This step is a step performed when the coordinates of the radiation receiving position become the coordinates of the processing receiving region 21 having the number n, and is the step of causing the galvanometric scanner 363 to move the radiation receiving region 22 in the X direction. The radiation receiving region 22 at the start of this step therefore abuts the edge of the processing receiving region 21 having the number n on one side in the X direction. In this step, the laser processing processor 310 controls the galvanometric scanner 363 in such a way that the radiation receiving region 22 moves at a constant speed from the one side toward the other side in the X direction. The control described above continues until step SP23. After starting the control, the laser processing processor 310 proceeds to step SP22 in the control flowchart.
This step is the step of irradiating the workpiece 20 with the laser light for the predetermined period, as step SP14 in the first embodiment. In this step, the laser processing processor 310 transmits the light emission trigger Tr to radiate the laser light onto the workpiece 20. In this step, the radiation receiving region 22 moves toward the other side in the X direction as the time elapses. In the present embodiment, the period for which the laser light is radiated is so adjusted that the radiation receiving region 22 overlaps a part of the radiation receiving region 22 irradiated with the laser light immediately before, and that the mmax-th radiation receiving region 22 abuts the edge of the processing receiving region 21 on the other side in the X direction, as in the step SP14 in the first embodiment. The galvanometric scanner 363 therefore moves the radiation receiving region 22 in such a way that the moved radiation receiving region 22 overlaps with a part of the radiation receiving region 22 irradiated with the laser light immediately before. The movement described above is the first process of causing the galvanometric scanner 363 capable of moving the radiation receiving region 22 in the X direction to move the radiation receiving region 22 so as to overlap with a part of the radiation receiving region 22 irradiated with the laser light immediately before. Radiating the laser light mmax times causes the entire processing receiving region 21 to be irradiated with the laser light, and the recess 30 is formed in the processing receiving region 21. After performing the mmax-th laser light radiation, the laser processing processor 310 proceeds to step SP23 in the control flowchart.
This step is the step of causing the galvanometric scanner 363 to stop moving the radiation receiving region 22 in the X direction. In this step, the laser processing processor 310 controls the galvanometric scanner 363 to stop moving the radiation receiving region 22. After stopping the movement of the radiation receiving region 22, the laser processing processor 310 proceeds to step SP15 in the control flowchart.
The laser processing method and the laser processing system 10 according to the present embodiment can shorten the processing period as compared with the case where the stage 350 moves the radiation receiving region 22 between different processing receiving regions 21, as the laser processing method and the laser processing system 10 according to the first embodiment. Furthermore, in the laser processing method and the laser processing system 10 according to the present embodiment, the galvanometric scanner 363 moves the radiation receiving region 22 in the X direction within each of the processing receiving regions 21, and the galvanometric scanner 361 moves the radiation receiving region 22 between the processing receiving regions 21 separate from each other in the X direction. The minimum travel distance of the radiation receiving region 22 moved by the galvanometric scanner 363, which moves the radiation receiving region 22 within each of the processing receiving regions 21, can therefore be smaller than in the case where the radiation receiving region 22 is moved by the single galvanometric scanner 361, so that the processing receiving region 21 can be processed with improved accuracy.
In the laser processing method according to the present embodiment, the galvanometric scanner 363 moves the radiation receiving region 22 in the X direction within each of the processing receiving regions 21, and the galvanometric scanners 361 and 362 move the radiation receiving region 22 between the processing receiving regions 21. The workpiece 20 can therefore be processed without moving the workpiece 20. For example, as compared with the case where the radiation receiving region 22 is moved between the processing receiving regions 21 while the workpiece 20 is moved at a constant speed in the X direction, the radiation receiving region 22 can be moved between the processing receiving regions 21 without synchronization with the movement of the workpiece 20, so that the processing accuracy can be improved.
The travel distance of the radiation receiving region 22 in the X direction in each of the processing receiving regions 21 is shorter than the travel distance of the radiation receiving region 22 between the processing receiving regions 21. The maximum amount of change in the optical path of the laser light caused by the galvanometric scanner 363 is therefore smaller than the maximum amount of change in the optical path of the laser light caused by the galvanometric scanner 361. In the present embodiment, since the galvanometric scanner 363 is located upstream from the galvanometric scanner 361 in the traveling direction of the laser light, the laser light is readily incident on the galvanometric scanner 361.
Note that the galvanometric scanner 363 may be located downstream from the galvanometric scanner 361 in the traveling direction of the laser light. Furthermore, in the present embodiment, since the workpiece 20 is not moved by the stage 350, the stage 350 may have a configuration in which the table 351 does not move.
The laser processing system 10 and the laser processing method according to a third embodiment will next be described. The same components as those described above have the same reference characters, and duplicate description of the same components will be omitted unless otherwise particularly described.
The dividing optical system 380 is disposed in the optical path between the mask 335 and the highly reflective mirror 331d. The dividing optical system 380 includes, for example, a beam splitter 381, reflects part of the laser light from the mask 335 toward the galvanometric scanner 366, and transmits the remainder of the laser light. The dividing optical system 380 thus divides the laser light from the mask 335 into two types of laser light, laser light La and laser light Lb.
The configuration of the highly reflective mirror 331d is, for example, the same as the configuration of the highly reflective mirrors 331a, 331b, and 331c. The highly reflective mirror 331d reflects the laser light La having passed through the beam splitter 381 toward the galvanometric scanner 363. The mirror 363b of the galvanometric scanner 363 reflects the laser light La from the highly reflective mirror 331d toward the mirror 361b, and the mirror 361b reflects the laser light La from the mirror 363b toward the mirror 362b. The mirror 362b reflects the laser light La from the mirror 361b toward the fθ lens 370. That is, the galvanometric scanners 361, 362, and 363 are provided for the laser light La. The fθ lens 370 collects the laser light La radiated from the galvanometric scanner 362 and brings the collected laser light La into focus at the surface of the workpiece 20 along the optical axis of the fθ lens 370.
The configuration of the galvanometric scanners 364, 365, and 366 is the same as the configuration of the galvanometric scanners 361, 362, and 363, and the galvanometric scanners 364, 365, and 366 include drivers 364a, 365a, and 366a and mirrors 364b, 365b, and 366b. The mirror 366b reflects the laser light Lb reflected off the beam splitter 381 toward the mirror 364b, and the mirror 364b reflects the laser light Lb from the mirror 366b toward the mirror 365b. The mirror 365b reflects the laser light Lb from the mirror 364b toward the fθ lens 371. That is, the galvanometric scanners 364, 365, and 366 are provided for the laser light Lb.
The galvanometric scanner 364 can change the optical path of the laser light Lb along the X direction with the aid of the mirror 364b to move the radiation receiving region 22 irradiated with the laser light Lb in the X direction. The galvanometric scanner 366 can change the optical path of the laser light Lb along the X direction with the aid of the mirror 366b to move the radiation receiving region 22 irradiated with the laser light Lb in the X direction. That is, the galvanometric scanners 364 and 366 are each a mover that can move the radiation receiving region 22 irradiated with the laser light Lb in the X direction. The galvanometric scanner 365 can change the optical path of the laser light Lb along the Y direction with the aid of the mirror 365b to move the radiation receiving region 22 irradiated with the laser light Lb in the Y direction. That is, the galvanometric scanner 365 is a mover that can move the radiation receiving region 22 irradiated with the laser light Lb in the Y direction.
The configuration of the fθ lens 371 is the same, for example, as that of the fθ lens 370. The fθ lens 371 is disposed in the optical path between the mirror 365b and the workpiece 20, and the optical axis of the fθ lens 371 extends along the Z direction. The fθ lens 371 collects the laser light Lb radiated from the galvanometric scanner 365 and brings the collected laser light Lb into focus at the surface of the workpiece 20 along the optical axis of the fθ lens 371.
In the present embodiment, out of the plural processing receiving regions 21 shown in
The operation of the laser processing processor 310 in the present embodiment will next be described.
The flowchart of the control performed by the laser processing processor 310 in the present embodiment is the same as the control flowchart in the second embodiment shown in
In the present embodiment, the number nmax of processing receiving regions 21, the number n, and the coordinates of each of the processing receiving regions 21 are set for each of the sets 26 of processing receiving regions 21. The number nmax of processing receiving regions 21 and the maximum number of times mmax the processing receiving regions 21 is irradiated with the laser light are the same in both the sets 26 of processing receiving regions 21.
In this step in the present embodiment, the laser processing processor 310 controls the galvanometric scanners 361 and 362 in such a way that the coordinates of the radiation receiving position irradiated with the laser light La become the coordinates of the processing receiving region 21 having the number n. The laser processing processor 310 controls the galvanometric scanners 364 and 365 in such a way that the coordinates of the radiation receiving position irradiated with the laser light Lb become the coordinates of the processing receiving region 21 having the number n. After moving the radiation receiving position, the laser processing processor 310 proceeds to step SP21 in the control flowchart.
In this step in the present embodiment, the laser processing processor 310 controls the galvanometric scanner 363 in such a way that the radiation receiving region 22 irradiated with the laser light La moves at a constant speed from the one side toward the other side in the X direction. The laser processing processor 310 controls the galvanometric scanner 366 in such a way that the radiation receiving region 22 irradiated with the laser light Lb moves at the constant speed from the one side toward the other side in the X direction. The control described above continues until step SP23. After starting the control described above, the laser processing processor 310 proceeds to step SP22 in the control flowchart.
In this step in the present embodiment, the laser processing processor 310 transmits the light emission trigger Tr to radiate the laser light La and the laser light Lb onto the workpiece 20, as in step SP22 in the second embodiment. The laser processing apparatus 300 in the present embodiment includes the dividing optical system 380. Therefore, the laser light La and the laser light Lb, into which the original laser light is divided by the dividing optical system 380, are simultaneously radiated to two of the plural processing receiving regions 21, and the simultaneous radiation for the predetermined period is repeated. In this step, the radiation receiving region 22 irradiated with the laser light La and the radiation receiving region 22 irradiated with the laser light Lb move toward the other side in the X direction as the time elapses. The period for which the laser light La and the laser light Lb are radiated is adjusted as in step SP22 in the second embodiment. Therefore, the radiation receiving region 22 irradiated with the laser light La overlaps with a part of the radiation receiving region 22 irradiated with the laser light La immediately before, and the radiation receiving region 22 irradiated with the laser light Lb overlaps with a part of the radiation receiving region 22 irradiated with the laser light Lb immediately before. The radiation receiving region 22 irradiated with the mmax-th laser light La abuts the edge of the processing receiving region 21 on the other side in the X direction, and the radiation receiving region 22 irradiated with the mmax-th laser light Lb abuts the edge of the processing receiving region 21 on the other side in the X direction. That is, the galvanometric scanners 363 and 366 move the radiation receiving regions 22 irradiated with the laser light La and the laser light Lb in such a way that the moved radiation receiving regions 22 overlap with parts of the radiation receiving regions 22 irradiated with the laser light La and the laser light Lb immediately before. The movement described above is the same as that in the first process described in the second embodiment. After radiating the mmax-th laser light La and laser light Lb, the laser processing processor 310 proceeds to step SP23 in the control flowchart.
In this step in the present embodiment, the laser processing processor 310 controls the galvanometric scanners 363 and 366 to stop moving the radiation receiving regions 22 irradiated with the laser light La and the laser light Lb. After stopping the movement described above, the laser processing processor 310 proceeds to step SP15 in the control flowchart.
The laser processing method and the laser processing system 10 according to the present embodiment can shorten the processing period as compared with the case where the stage 350 moves the radiation receiving region 22 between different processing receiving regions 21, as the laser processing method and the laser processing system 10 according to the first embodiment.
In the laser processing method according to the present embodiment, two of the plural processing receiving regions 21 are simultaneously irradiated with the pulse laser light. The laser processing method according to the present embodiment can therefore further shorten the processing period.
Note that the dividing optical system 380 may divide the laser light from the mask 335 into three or more types of laser light, and in this case, for example, three galvanometric scanners are provided for each of the three or more types of laser light into which the optical laser light is divided. In the configuration described above, three or more of the plural processing receiving regions 21 can be simultaneously irradiated with the pulse laser light. Note that it is preferable that the number of types of laser light into which the original laser light is divided is smaller than or equal to half the number of processing receiving regions 21, and that the number of processing receiving regions 21 is an integral multiple of the number of types of laser light into which the original laser light is divided.
The laser processing apparatus 300 may not include the galvanometric scanner 363 or 366. In this case, for example, the stage 350 moves the radiation receiving region 22 within each of the processing receiving regions 21 in the X direction.
The present disclosure has been described above with reference to the embodiments by way of example, and the embodiments described above can be modified as appropriate. For example, the laser light radiated to the workpiece 20 has a rectangular outer shape elongated in the Y direction, and may instead have a shape other than a rectangular shape, for example, a circular shape.
The laser processing apparatus 300 may not include the fθ lens 370 or 371.
The description above is intended to be illustrative and the present disclosure is not limited thereto. Therefore, it would be obvious to those skilled in the art that various modifications to the embodiments of the present disclosure would be possible without departing from the spirit and the scope of the appended claims. Further, it would be also obvious for those skilled in the art that embodiments of the present disclosure would be appropriately combined. The terms used throughout the present specification and the appended claims should be interpreted as non-limiting terms. For example, terms such as “comprise”, “include”, “have”, and “contain” should not be interpreted to be exclusive of other structural elements. Further, indefinite articles “a/an” described in the present specification and the appended claims should be interpreted to mean “at least one” or “one or more.” Further, “at least one of A, B, and C” should be interpreted to mean any of A, B, C, A+B, A+C, B+C, and A+B+C as well as to include combinations of any thereof and any other than A, B, and C.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-212513 | Dec 2023 | JP | national |
