JP5909352B2 - Pulse laser processing apparatus and pulse laser processing method - Google Patents

Description

  The present invention relates to a pulse laser processing apparatus and a pulse laser processing method for processing a workpiece surface with a pulse laser beam.

  In recent years, flat panel displays (FPDs) such as liquid crystal panels, for example, have been required to have a member that has been subjected to high-precision microfabrication on a large area, for example, on the order of μm or less, with an increase in size. . Various studies have been made on microfabrication of large roll molds for sheet creation, molds having fine shapes for blind grooves and deep microlenses, difficult-to-cut materials, etc., which are difficult to produce by conventional machining.

  On the other hand, it is known that, for example, a fine pattern of 1 μm or less can be easily formed on a metal surface by ablation processing using an ultrashort pulse laser beam having a pulse width of the order of picoseconds (ps) or less. And so far, various methods have been proposed for techniques for processing the surface of a workpiece made of a polymer material containing a resin, a semiconductor material, a glass material, a metal material, etc. by this ultrashort pulse laser processing ( For example, see Patent Document 1).

In pulse laser processing, when fine processing is performed on a material, the surface of the workpiece is irradiated by irradiating a laser beam pulse with a high peak power density (for example, about 100 MW / cm ² or more) focused on a minute spot. Adopt processing method by ablation (transpiration) to be removed. However, scattered workpiece residues (hereinafter also referred to as debris) are generated, and the processing quality deteriorates.

  Conventionally, in order to remove debris, for example, assistance with air or an inert gas, evacuation of a processing site, and the like are performed. Alternatively, the debris may be removed using a laser annealing apparatus different from the processing. However, there are problems such as removal efficiency and equipment costs, and sufficient effects are not obtained.

  In pulse laser processing, a diffractive optical component is provided in the optical path between the galvano mirror that forms the optical path that guides the output light from the laser oscillator to the workpiece and the laser oscillator, and the laser light is branched to process the laser light. A method of irradiating an object is disclosed (Patent Document 2).

Japanese Patent No. 4612733 Japanese Patent No. 4218209

  In view of the above circumstances, the present invention provides a pulse laser machining apparatus and a pulse laser machining method that can perform debris removal of a workpiece at a low cost in a short time by simultaneously processing and cleaning the workpiece. The purpose is to provide.

A pulse laser processing apparatus according to an aspect of the present invention uses a reference clock oscillation circuit that generates a clock signal, and the passage and blocking of a first pulse laser beam for processing a workpiece synchronized with the clock signal as the clock signal. A first pulse picker that switches in synchronization; a second pulse picker that switches between passage and blocking of a second pulse laser beam for cleaning a workpiece synchronized with the clock signal in synchronization with the clock signal; A first pulse picker controller for controlling the first pulse picker based on the number of light pulses of the first pulse laser beam; and the first pulse based on the number of light pulses of the second pulse laser beam. independently of the picker and a second pulse picker control unit for controlling the second pulse picker, a subsequent stage of the first pulse picker A first attenuator for adjusting the output of the first pulse laser beam, and a second attenuator for adjusting the output of the second pulse laser beam provided after the second pulse picker, A multiplexer that is provided downstream of the first attenuator and the second attenuator and multiplexes the first pulse laser beam and the second pulse laser beam to generate a combined pulse laser beam; A laser beam scanner that scans the combined pulse laser beam only in a one-dimensional direction in synchronization with the clock signal, and a stage that can place a workpiece and moves in a direction orthogonal to the one-dimensional direction. And the multiplexer separates the optical axis of the first pulse laser beam and the optical axis of the second pulse laser beam in a direction perpendicular to the one-dimensional direction. Multiplexes in the state, characterized by lower than the energy density of the first pulse laser beam on the workpiece an energy density of the second pulse laser beam on the workpiece.

  In the apparatus of the above aspect, it is preferable that the stage moves in a direction orthogonal to the one-dimensional direction based on a scanning angle signal from the laser beam scanner.

  In the apparatus of the above aspect, a laser oscillator that emits a basic pulse laser beam synchronized with the clock signal, and a demultiplexer that demultiplexes the basic pulse laser beam into the first pulse laser beam and the second pulse laser beam. It is desirable to further comprise a vessel.

  In the apparatus of the above aspect, the apparatus further comprises: a first beam shaper that shapes the shape of the first pulse laser beam; and a second beam shaper that shapes the shape of the second pulse laser beam. It is preferable that the second beam shaper includes a beam diameter changing unit that makes a beam diameter of the second pulse laser beam variable.

  In the apparatus of the above aspect, an input unit for inputting machining data of a workpiece, a machining pattern generation unit for converting the machining data into a machining pattern, and a first sub machining pattern for machining the workpiece pattern And a machining pattern dividing unit that divides the workpiece into a second sub machining pattern for cleaning the workpiece, wherein the first pulse picker control unit is configured to use the first pulse based on the first sub machining pattern. It is preferable that the picker is controlled, and the second pulse picker control unit controls the second pulse picker based on the second sub machining pattern.

  In the apparatus of the above aspect, the first and second sub-machining patterns are preferably machining tables described by the number of light pulses of a pulse laser beam.

  In the apparatus of the above aspect, it is preferable that the laser beam scanner is constituted by a galvanometer scanner, and the pulse picker is constituted by an acousto-optic element (AOM) or an electro-optic element (EOM).

According to another aspect of the present invention, there is provided a pulse laser processing method, wherein a workpiece is placed on a stage, a clock signal is generated, and an optical pulse of a first pulse laser beam for processing the workpiece synchronized with the clock signal. Based on the number of pulses, switching between irradiation and non-irradiation of the first pulse laser beam in synchronization with the clock signal, and based on the number of light pulses of the second pulse laser beam for workpiece cleaning synchronized with the clock signal Independently of irradiation and non-irradiation of the first pulse laser beam, the irradiation and non-irradiation of the second pulse laser beam are switched in synchronization with the clock signal, and the first pulse laser beam and the second irradiation are switched. Are combined with the pulse laser beam to generate a combined pulse laser beam, and the combined pulse laser beam is synchronized with the clock signal on the surface of the workpiece. After scanning in the one-dimensional direction by the beam scanner and scanning the combined pulse laser beam in the one-dimensional direction, the stage is moved in a direction orthogonal to the one-dimensional direction, and further synchronized with the clock signal. A pulsed laser processing method for scanning the combined pulsed laser beam in the one-dimensional direction, wherein the first pulsed laser beam and the second pulsed laser beam have their respective optical axes in the one-dimensional direction. And the energy density of the second pulse laser beam on the workpiece is made lower than the energy density of the first pulse laser beam on the workpiece. The workpiece is processed by the first pulse laser beam, and the workpiece is cleaned by the second pulse laser beam. And wherein the Ukoto.

  In the method of the above aspect, it is preferable that the stage moves in a direction orthogonal to the one-dimensional direction based on a scanning angle signal from the laser beam scanner.

  In the method of the above aspect, it is preferable that a beam diameter of the second pulse laser beam is larger than a beam diameter of the first pulse laser beam.

  According to the present invention, there is provided a pulse laser processing apparatus and a pulse laser processing method capable of performing debris removal of a workpiece at a low cost in a short time by simultaneously processing and cleaning the workpiece. It becomes possible.

It is a block diagram of the pulse laser processing apparatus of an embodiment. It is explanatory drawing of the laser beam scanner using the galvanometer scanner of embodiment. It is explanatory drawing of the scanning of the laser beam scanner of the pulse laser processing apparatus of embodiment. It is a figure which shows the specific example of the table which is an example of the definition format of the 1st or 2nd sub process pattern of embodiment. It is a signal waveform diagram explaining timing control of the pulse laser processing apparatus of an embodiment. It is a signal waveform diagram explaining timing control of the pulse laser processing apparatus of an embodiment. It is a signal waveform diagram explaining the timing control of the pulse picker operation of the pulse laser processing apparatus of the embodiment. It is a schematic diagram explaining the process of the to-be-processed object by embodiment. It is a figure which shows one processing example by the pulse laser processing apparatus of embodiment. It is a figure which shows the scanning of the specific one-dimensional direction in the process of FIG. It is a figure which shows the two-dimensional process about the specific layer in the process of FIG.

  Hereinafter, a pulse laser processing apparatus and a pulse laser processing method according to embodiments of the present invention will be described with reference to the drawings.

  In this specification, “in the front stage” and “in the rear stage” of a certain member is a concept based on the traveling direction of the laser beam. Therefore, a member on the side of the laser beam traveling direction with respect to a certain member is a “rear stage” member.

  The pulse laser processing apparatus of the present embodiment synchronizes the reference clock oscillation circuit for generating the clock signal and the passage and blocking of the first pulse laser beam for processing the workpiece synchronized with the clock signal in synchronization with the clock signal. A first pulse picker for switching, a second pulse picker for switching the passage and blocking of a second pulse laser beam for workpiece cleaning synchronized with the clock signal in synchronization with the clock signal, and the first pulse laser beam A first pulse picker controller for controlling the first pulse picker based on the number of optical pulses of the second pulse picker, and a second pulse picker for controlling the second pulse picker based on the number of optical pulses of the second pulse laser beam A control unit, and a first attenuator that is provided after the first pulse picker and adjusts the output of the first pulse laser beam; A second attenuator provided after the second pulse picker for adjusting the output of the second pulse laser beam; a second attenuator provided after the first attenuator and the second attenuator; A multiplexer that combines the second pulse laser beam to generate a combined pulse laser beam, a laser beam scanner that scans the combined pulse laser beam in only one dimension in synchronization with the clock signal, and a workpiece A stage on which an object can be placed and moves in a direction orthogonal to the one-dimensional direction. Then, the multiplexer multiplexes in a state where the optical axis of the first pulse laser beam and the optical axis of the second pulse laser beam are separated in a direction orthogonal to the one-dimensional direction, and the second on the workpiece. The energy density of the pulse laser beam is made lower than the energy density of the first pulse laser beam on the workpiece.

  The pulse laser processing apparatus of the present embodiment individually controls on / off of a workpiece processing pulse laser beam and a cleaning pulse laser beam synchronized with the same clock signal. The two pulsed laser beams can be combined and irradiated onto the workpiece while their optical axes are separated in a direction perpendicular to the scanning direction. With this configuration, it is possible to simultaneously process the workpiece and clean the debris generated by this processing. Therefore, debris removal of the workpiece can be realized in a short time and at low cost.

  The pulse laser processing apparatus of the present embodiment directly or indirectly synchronizes the pulse of the laser oscillator, the passage and blocking of the pulse laser beam, and the scanning of the laser beam scanner with the same reference clock signal. In this way, the positioning accuracy of the irradiation spot of the pulse laser beam is improved by maintaining the synchronization between the laser system and the beam scanning system.

  Further, it is possible to control the passage and blocking of the pulse laser beam based on the number of light pulses of the pulse laser beam. As a result, it becomes easy to maintain the synchronization of the pulse of the laser oscillator, the passage and block of the pulse laser beam, and the scanning of the laser beam scanner. Further, the configuration of the control circuit can be simplified.

  The pulse laser processing apparatus according to the present embodiment further improves the positioning accuracy of the irradiation spot of the pulse laser beam, and easily realizes stable fine processing and cleaning of a large-sized workpiece surface and their speeding up.

  In addition, high-quality products that can selectively clean the surface of the workpiece near the processing pattern range with high accuracy can be obtained at low cost by performing processing and cleaning with two combined pulsed laser beams. It can be manufactured.

  FIG. 1 is a configuration diagram of a pulse laser processing apparatus according to the present embodiment. The pulse laser processing apparatus 10 includes, as main components, a processing data input unit 11, a laser oscillator 12, a duplexer 38, a first pulse picker 14a, a second pulse picker 14b, a first beam shaper 16a, Second beam shaper 16b, first attenuator 17a, second attenuator 17b, multiplexer 40, laser beam scanner 18, XY stage unit 20, first pulse picker control unit 22a, second pulse picker control A section 22b, a processing pattern dividing section 50, and a processing control section 24 are provided. The processing control unit 24 includes a reference clock oscillation circuit 26 that generates a desired clock signal S1 and a processing pattern generation unit 54.

  In the reference clock oscillation circuit 26, a reference clock signal S1 is generated.

  The laser oscillator 12 is configured to emit a basic pulse laser beam PL synchronized with the reference clock signal S1. The laser oscillator 12 desirably oscillates a ps (picosecond) laser beam or fs (femtosecond) laser beam which is an ultrashort pulse.

  Here, the laser wavelength emitted from the laser oscillator 12 is selected in consideration of the light absorptivity, light reflectance, etc. of the workpiece. For example, in the case of a workpiece made of a metal material including Cu, Ni, difficult-to-cut material SKD11, or diamond-like carbon (DLC), use the second harmonic (wavelength: 532 nm) of an Nd: YAG laser. Is desirable.

  The demultiplexer 38 demultiplexes the basic pulse laser beam PL into a first pulse laser beam PL1a for processing and a second pulse laser beam PL1b for cleaning. The duplexer 38 includes, for example, a first mirror 38a and a second mirror 38b. The first mirror 38a is, for example, a half mirror, and the second mirror 38b is, for example, a folding mirror. The first mirror 38a is, for example, a half mirror having a transmittance of 50% and a reflectance of 50%.

  The first pulse picker 14 a is provided in the optical path after the laser oscillator 12 and the demultiplexer 38 and before the laser beam scanner 18. And, it is configured to switch between processing and non-processing of the workpiece (workpiece W) by switching between passage and blocking (on / off) of the first pulse laser beam PL1a in synchronization with the reference clock signal S1. In this way, the first pulse laser beam PL1a becomes the first modulated pulse laser beam PL2a which is controlled to be turned on / off for the processing of the workpiece by the operation of the first pulse picker 14a.

  The first pulse picker 14a is preferably composed of an acousto-optic element (AOM), for example. Further, for example, a Raman diffraction type electro-optic element (EOM) may be used.

  The first beam shaper 16a turns the incident first pulse laser beam PL2a into a first pulse laser beam PL3a shaped into a desired shape. For example, a beam expander that expands the beam diameter at a constant magnification. Further, for example, an optical element such as a homogenizer for making the light intensity distribution in the beam cross section uniform may be provided. Further, for example, an element that makes the beam cross section circular or an optical element that makes the beam circularly polarized light may be provided.

  The first attenuator 17a is provided after the first pulse picker 14a, adjusts the output of the first pulse laser beam PL3a, and emits it as the first pulse laser beam PL4a. For example, the first attenuator 17a monitors the output of the first pulse laser beam PL4a with a beam sampler, and adjusts the first pulse laser beam PL3a to a desired output with a controller based on the monitoring result of the beam sampler. 1 pulse laser beam PL4a.

  The second pulse picker 14 b is provided in the optical path after the laser oscillator 12 and the duplexer 38 and before the laser beam scanner 18. Then, the presence or absence of cleaning of the workpiece (workpiece W) is switched by switching the passage and blocking (on / off) of the second pulse laser beam PL1b in synchronization with the reference clock signal S1. As described above, the second pulse laser beam PL1b becomes the second modulated pulse laser beam PL2b, which is controlled to be turned on / off for cleaning the workpiece by the operation of the second pulse picker 14b.

  The second pulse picker 14b is preferably composed of an acousto-optic element (AOM), for example. Further, for example, a Raman diffraction type electro-optic element (EOM) may be used.

  The second beam shaper 16b turns the incident second pulse laser beam PL2b into a second pulse laser beam PL3b shaped into a desired shape. For example, a beam expander that expands the beam diameter at a constant magnification. Further, for example, an optical element such as a homogenizer for making the light intensity distribution in the beam cross section uniform may be provided. Further, for example, an element that makes the beam cross section circular or an optical element that makes the beam circularly polarized light may be provided.

  The second beam shaper 16b preferably includes a half-wave plate that rotates the plane of polarization by 90 degrees. By providing the half-wave plate, the polarization plane of the second pulse laser beam PL3b is rotated by 90 degrees with respect to the polarization plane of the first pulse laser beam PL3a. For this reason, it is possible to suppress mutual interference when combined later, and to realize higher-precision processing and cleaning.

  Moreover, it is desirable that the second beam shaper 16b for shaping the second pulse laser beam for cleaning the workpiece includes a beam diameter changing unit that makes the beam diameter of the second pulse laser beam variable. The beam diameter changing unit is, for example, a beam expander.

  In this embodiment mode, the energy density of the second pulse laser beam on the workpiece is set to the energy density of the first pulse laser beam on the workpiece so that the workpiece is not damaged during cleaning. Lower than. For example, the energy density of the beam on the workpiece can be reduced by making the beam diameter larger than that of the first pulse laser beam at the beam diameter changing unit.

  The second attenuator 17b is provided after the second pulse picker 14b, adjusts the output of the second pulse laser beam PL3b, and emits the second pulse laser beam PL4b. For example, the second attenuator 17b monitors the output of the second pulse laser beam PL4b with a beam sampler, and adjusts the second pulse laser beam PL3b to a desired output with a controller based on the monitoring result of the beam sampler. 2 pulse laser beam PL4b.

  By adjusting the output of the first pulse laser beam or the second pulse laser beam with the first attenuator 17a and the second attenuator 17b, the energy density of the second pulse laser beam on the workpiece is adjusted. It becomes possible to make it lower than the energy density of the 1st pulse laser beam on a workpiece.

  The multiplexer 40 includes, for example, a first mirror 40a and a second mirror 40b. The first mirror 40a is, for example, a folding mirror, and the second mirror 40b is, for example, a half mirror. The first mirror 40a is held by, for example, a holder having a drive system using a piezo element, and enables fine position adjustment.

  The multiplexer 40 adjusts the first mirror 40a so that the optical axis of the first pulse laser beam PL4a and the optical axis of the second pulse laser beam PL4b are orthogonal to the scanning direction on the workpiece. Are combined in a separated state to generate a combined pulse laser beam (parallel combined pulse laser beam) PL5.

  In this way, by patterning two series of pulsed laser beams that are independently controlled to be turned on / off in a separated state to generate a parallel multiplexed pulsed laser beam, pattern processing of the workpiece can be performed with the same scanning. And cleaning can be performed simultaneously.

  The laser beam scanner 18 is configured to scan the combined pulsed laser beam PL5 only in the one-dimensional direction in synchronization with the reference clock signal S1. In this way, by scanning the combined pulse laser beam PL5 in synchronization with the reference clock signal S1, the positioning accuracy of the irradiation spot of the pulse laser beam is improved. In FIG. 1, the scan command signal S2 is synchronized with the reference clock signal S1.

  In addition, it is possible to improve the positioning accuracy of the irradiation spot of the pulse laser beam by performing scanning only in the one-dimensional direction. This is because a laser beam scanner that scans in a two-dimensional direction is structurally deteriorated with respect to a laser beam scanner that scans only in a one-dimensional direction.

  As the laser beam scanner 18, for example, a galvanometer scanner provided with a uniaxial scan mirror can be cited.

  FIG. 2 is an explanatory diagram of a laser beam scanner using a galvanometer scanner.

  The galvanometer scanner has a uniaxial scan mirror 28, a galvanometer 30, and a laser beam scanner controller 32. Here, the galvanometer 30 is provided with a scanning mirror rotation drive mechanism such as servo control by feedback from the scanning angle sensor 36, for example.

  A scanning command signal S2 synchronized with the clock signal S1 is sent from the processing control unit 24. The galvanometer 30 is configured to be driven and controlled by a driving signal S3 from the laser beam scanner control unit 32 based on the scanning command signal S2. The galvanometer scanner scans the combined pulsed laser beam PL5 totally reflected by the uniaxial scanning mirror 28 according to the rotational movement (swinging) of the scanning mirror as indicated by the arrow in FIG.

  The laser beam scanner 18 is provided with a scanning angle sensor 36. In the case of a galvanometer scanner, the rotation position of the single-axis scan mirror 28 is detected by a rotary encoder or the like. Then, the scanning angle sensor 36 sends the detected scanning angle detection signal S4 to the laser beam scanner control unit 32 and is used for driving control of the galvanometer 30. Further, the laser beam scanner control unit 32 transmits a scanning angle signal S5 to the processing control unit 24 based on the scanning angle detection signal S4.

  Then, the parallel combined pulse laser beam PL5 reflected by the uniaxial scanning mirror 28 passes through the fθ lens 34 and is scanned in parallel in a one-dimensional direction at a constant speed V, for example, parallel to an image height H = fθ. The combined pulse laser beam PL6 is obtained. The parallel combined pulse laser beam PL6 is projected onto the workpiece W as irradiation pulse light for finely processing the surface of the workpiece W held on the XY stage unit 20.

  The parallel combined pulse laser beam PL6 is a pulse laser beam in a state where the two pulse laser beams are separated from each other by a distance “Ly”, for example, in a direction orthogonal to the one-dimensional direction that is the scanning direction.

  In addition to the galvanometer scanner, for example, a polygon scanner, a piezo scanner, a resonant scanner, or the like can be applied to the laser beam scanner 18.

  In any of the above laser beam scanners, it is important from the viewpoint of improving the processing accuracy that the laser beam scanner is configured to be controlled so as to ensure a constant scanning speed V within a processing range.

  FIG. 3 is a diagram for explaining scanning of the laser beam scanner of the pulse laser processing apparatus according to the present embodiment. As shown in FIG. 3, the position range corresponding to the scan end position from the scan start position in the scan angle range of the scan mirror includes an acceleration period, a stable region, and a deceleration period. In order to increase the processing accuracy, it is important that the apparatus is configured to control the scanning speed V to be constant within a stable range including the actual processing range.

  The XY stage unit 20 can place the workpiece W and can freely move in the XY direction including the direction orthogonal to the one-dimensional direction in which the pulse laser beam is scanned, its drive mechanism unit, and the XY stage. For example, a position sensor having a laser interferometer for measuring the position is provided. Here, the XY stage can be moved continuously or stepped in a two-dimensional wide range, for example, a distance range in the X direction and Y direction of about 1 m. And it is comprised so that the positioning accuracy and movement error may become the high precision of the range of a submicron.

  In the machining data input unit 11, machining data of a workpiece is input. The machining data includes, for example, designation of a three-dimensional shape, dimensions, number of shapes, arrangement, workpiece material name, workpiece dimensions, and the like. The designation of the three-dimensional shape is performed by, for example, bitmap format data in which the processed shape of the workpiece is included as color data. The processed data input unit 11 is, for example, a storage medium for storing processed data, for example, a storage medium reading device such as a semiconductor memory or a DVD (Digital Video Disk).

  The processing control unit 24 integrates and controls the processing by the pulse laser processing apparatus based on the processing data input from the processing data input unit 11. The processing control unit 24 includes a reference clock oscillation circuit 26 that generates a reference clock signal S1.

  Further, the machining control unit 24 includes a machining pattern generation unit 54 that converts the machining data input from the machining data input unit 11 into a machining pattern of parameter data in accordance with actual machining. The machining data is analyzed by the machining data analysis unit of the machining pattern generation unit 54. The processing amount of the unit light pulse can be obtained empirically from conditions such as the operation of the laser oscillator used for processing, the irradiation pulse energy, which is the beam scanning condition, the beam spot diameter, the repetition frequency, the scanning speed, and the stage feed amount. .

  Based on the above conditions, the three-dimensional shape is further decomposed into a two-dimensional layer and converted into two-dimensional data based on bitmap data for each layer. This two-dimensional data is converted into pulse picker operation data (number of machining pulses, number of non-machining pulses, number of standby length pulses).

  Further, the machining pattern generation unit 54 defines an area that needs to be cleaned from the two-dimensional data, and the operation data of the pulse picker (number of machining (cleaning) pulses, number of non-machining (non-cleaning) pulses, number of standby length pulses) Convert to

  The processing pattern generated by the processing pattern generation unit 54 is, for example, a processing table in which the standby length, processing length (cleaning length), and non-processing length (non-cleaning length) for each scan of the laser beam are described in units of pulses. Is

  The processing pattern dividing unit 50 has a function of dividing the processing pattern generated by the processing pattern generation unit 54 into a first sub processing pattern for processing a workpiece and a second sub processing pattern for cleaning. The first sub-machining pattern is used to generate the first pulse laser beam PL2a from the first pulse laser beam PL1a. Further, the second sub-machining pattern is used to generate the second pulse laser beam PL2b from the second pulse laser beam PL1b.

  The first sub machining pattern is, for example, a machining table in which the standby length, machining length, and non-machining length for each scan of the laser beam are described in units of the number of pulses of the first pulse laser beam PL1a. The second sub-processing pattern is, for example, a cleaning table in which the standby length, cleaning length, and non-cleaning length for each scan of the laser beam are described in units of the number of pulses of the second pulse laser beam PL1b.

  FIG. 4 is a diagram showing a specific example of the processing / cleaning table which is an example of the definition format of the first or second sub-processing pattern. A certain layer processing / cleaning table is shown. As shown in FIG. 4, the processing / cleaning table describes, for example, a standby length, a processing length (or cleaning length), and a non-processing length (or non-cleaning length) based on the number of light pulses of the pulse laser beam. To do. In FIG. 4, the stage feed (μm) is a movement distance moved in the Y direction orthogonal to the X direction by the XY stage unit after the scanning in the X direction by the laser beam scanner 18 is completed.

  The first sub machining pattern is transferred to the first pulse picker control unit 22a and used for controlling the first pulse picker 14a. Further, the second sub machining pattern is transferred to the second pulse picker control unit 22b and used for controlling the second pulse picker 14b.

  The processing control unit 24 and the processing pattern division unit 50 are hardware such as a microcomputer (MCU), a microprocessor (MPU), a digital signal processor (DSP), a semiconductor memory, a circuit board, or the like made of a semiconductor integrated circuit. And a combination of software.

  Next, a pulse laser processing method using the pulse laser processing apparatus 10 will be described. In this pulse laser processing method, a workpiece (work) is placed on a stage, a clock signal is generated, and based on the number of optical pulses of a first pulse laser beam for processing a workpiece synchronized with the clock signal, Switching between irradiation and non-irradiation of the first pulse laser beam in synchronization with the clock signal, and in synchronization with the clock signal based on the number of light pulses of the second pulse laser beam for workpiece cleaning synchronized with the clock signal Switching between irradiation and non-irradiation of the second pulse laser beam, the first pulse laser beam and the second pulse laser beam are combined to generate a combined pulse laser beam, and combined on the workpiece surface. The pulsed laser beam is scanned in a one-dimensional direction by a laser beam scanner in synchronization with a clock signal, and the combined pulsed laser beam is scanned in a one-dimensional direction. And moving the stage in a direction orthogonal to the direction, which is further pulsed laser processing method for synchronously scanning the combined pulsed laser beam in the one-dimensional direction to the clock signal. Then, the first pulse laser beam and the second pulse laser beam are combined with each optical axis being separated in a direction orthogonal to the one-dimensional direction, and the second pulse laser beam on the work piece. Is made lower than the energy density of the first pulse laser beam on the workpiece, the workpiece is processed by the first pulse laser beam, and the workpiece is cleaned by the second pulse laser beam. Do.

  5 and 6 are signal waveform diagrams illustrating timing control of the pulse laser processing apparatus according to the present embodiment. When machining the workpiece W placed on the stage, the laser oscillator 12 operates autonomously with most of the laser oscillation controlled by a built-in control unit. However, as shown in FIG. 5, the pulse oscillation timing is controlled by the reference clock signal S1 having the cycle Tp generated by the reference clock oscillation circuit.

  In this way, the first pulse laser beam PL1a for processing synchronized with the reference clock signal S1 and the second pulse laser beam PL1b for cleaning are generated.

  The first pulse laser beam PL1a and the second pulse laser beam PL1b are combined by the combiner 40, thereby generating a parallel combined pulse laser beam PL5.

  The laser beam scanner 18 starts scanning at the scanning start position (scanning origin) shown in FIG. 3 based on the scanning start signal S11. At this time, as shown in FIG. 5, the laser beam scanner 18 receives an instruction from a scanning command signal S2 having a cycle Ts generated by the processing control unit 24 in synchronization with the rising (or falling) of the reference clock signal S1. . The laser beam scanner control unit 32 controls driving of the galvanometer 30 based on the scanning command signal S2.

  As described above, the laser beam scanner 18 scans the pulse laser beam in a one-dimensional direction in synchronization with the reference clock signal S1. At this time, a pattern is processed on the surface of the workpiece W by switching between irradiation and non-irradiation of the pulse laser beam. Or, perform cleaning. Note that the scan command signal S2 conforms to the XY2-100 protocol, and follows an absolute scan angle command based on the position of the scan angle “0 degree” of the galvanometer 30 at, for example, 100 kHz (Ts = 10 μsec).

  After scanning the combined pulsed laser beam PL6 in the one-dimensional direction, the stage is moved in a direction orthogonal to the one-dimensional direction, and the combined pulsed laser beam S6 is moved in the one-dimensional direction in synchronization with the reference clock signal S1. Scan in the direction. In this way, the scanning of the pulse laser beam in the one-dimensional direction and the movement of the stage are alternately performed in the direction orthogonal to the one-dimensional direction.

  Here, the scanning angle signal S5 from the laser beam scanner 18 instructs the movement timing of the XY stage unit. Assuming that the one-dimensional scanning direction of the laser beam scanner 18 is the X-axis direction, step movement or continuous movement of a predetermined width in the Y-axis direction is performed according to the movement timing. Thereafter, the pulse laser beam is scanned in the X direction.

  Here, in the acceleration period of FIG. 3, the laser beam scanner 18 is controlled by the scanning command signal S2 so that the scanning speed becomes a stable scanning speed V at an early stage. It is empirically clear that the reproducibility of the scanning angle of the uniaxial scanning mirror 28 under the optimum condition is about 10 μrad / pp in the stable region. This value becomes a scanning position reproducibility of 1 μm / pp when an fθ lens having a focal length of 100 mm is used.

  However, the repeated stability of the scanning speed V during the acceleration period deteriorates to about 10 times in the long-term scanning. For this reason, the position of the processing origin in FIG. 3 may vary from scan to scan. Therefore, a synchronization angle (θsy) for synchronizing the oscillation of the pulse laser beam and the beam scanning is set in a sufficiently stable region after the end of the acceleration period. The scanning angle range until reaching a sufficiently stable region is, for example, about 2.3 degrees to 3.4 degrees when an fθ lens having an acceleration period of 1 msec to 1.5 msec and a focal length of 100 mm is used.

Then, as shown in FIG. 6, the scanning angle sensor 36 detects this synchronization angle as a synchronization angle detection signal S12. Then, a phase difference θi between the scan command signal S2 corresponding to the scanning angle theta ₀ from the scanning start position in detecting the synchronization angle. Then, based on this phase difference θ _i , the distance to the processing origin with respect to the scanning command signal S2 is corrected.

As the correction value of the distance to the processing origin, the first scanning (i = 1) at the time of processing is stored as a reference correction value. Then, each time scanning from the n-th scanning start position where i = n thereafter, the difference between the phase difference θ _n and the phase difference θ ₁ is processed for the scanning command signal S2 for the first scanning of the n-th scanning. The distance correction value to the origin is used. The determined distance correction value, the scanning command signal to the scanning angle theta ₀ from the scanning start position: By giving the (S2 absolute scanning angle command) after the scanning command signal (S2), machining origin position is corrected. In this way, even if the scanning speed varies during the acceleration period of the laser beam scanner 18, it is possible to match the processing origin positions during the first scan and the n-th scan.

  As described above, after scanning the parallel multiplexed pulse laser beam PL6 in the one-dimensional direction, the stage is moved in the direction orthogonal to the one-dimensional direction, and further, the parallel multiplexed pulse is synchronized with the reference clock signal S1. In the case where the laser beam PL6 is scanned in the one-dimensional direction, the machining origin position for each scan is matched, and the machining accuracy is improved.

  When the parallel combined pulse laser beam PL6 is scanned in the one-dimensional direction, irradiation and non-irradiation of the parallel combined pulse laser beam PL6 are switched in synchronization with the reference clock signal S1 based on the number of optical pulses. . Irradiation and non-irradiation of the pulse laser beam are performed using the first and second pulse pickers 14a and 14b.

  FIG. 7 is a signal waveform diagram illustrating timing control of the pulse picker operation of the pulse laser processing apparatus according to the present embodiment. A machining pattern signal S7 generated from the machining data and managed by the number of light pulses, for example, is output from the machining pattern generation unit 54.

As shown in FIG. 7, the first pulse laser beam PL1a from the reference clock signal S1 periods Tp and t ₁ delay shutoff / passage is controlled on the basis of the first pulse picker drive signal S6a. The scanning of the laser beam scanner 18 is synchronized with the blocking / passing of the first pulse laser beam by synchronizing the generation timing of the scanning command signal S2 with the reference clock signal S1.

For example, the first pulse picker driving signal S6a samples the first machining pattern signal S7a generated by the machining pattern dividing unit 54 from the machining pattern signal S7 at the rising edge of the reference clock signal S1. The rises in t ₂ hours delay from the rise of one clock of the first clock signal S1a. After the number of clocks corresponding to the number of desired pulses, the state in which the first processing pattern signal S7a becomes inactive sampled at the rising edge of the reference clock signal S1, falls with a delay t ₃ hours.

Then, by the first pulse picker drive signal S6a, the operation of the first pulse picker 14a occurs after a delay time _{t 4} and _{t 5} elapses. By the operation of the first pulse picker 14a, the first pulse laser beam PL1a is extracted as the first modulated pulse laser beam PL2a.

Similarly, the second pulse laser beam PL1b from the reference clock signal S1 periods Tp and t ₁ delay shutoff / passage is controlled based on the second pulse picker drive signal S6b. Note that the scanning of the laser beam scanner 18 is synchronized with the blocking / passing of the second pulse laser beam by synchronizing the generation timing of the scanning command signal S2 with the reference clock signal S1.

For example, the second pulse picker drive signal S6b samples the second machining pattern signal S7b generated by the machining pattern dividing unit 54 from the machining pattern signal S7 at the rising edge of the reference clock signal S1. Then, it rises from the rising one clock of the reference signal S1 with a delay t ₂ hours. After the number of clocks corresponding to the number of required pulses, a state where the second processing pattern signal S7b becomes inactive sampled at the rising edge of the reference signal S1, it falls with a delay t ₃ hours.

Then, by the second pulse picker drive signal S6b, the operation of the second pulse picker 14b occurs after a delay time _{t 4} and _{t 5} elapses. By the operation of the second pulse picker 14b, the second pulse laser beam PL1b is extracted as the second modulated pulse laser beam PL2b.

  The first modulated pulse laser beam PL2a and the second modulated pulse laser beam PL2b are multiplexed by the multiplexer 40 (FIG. 1), thereby generating a parallel multiplexed pulse laser beam PL5 synchronized with the reference clock signal S1. Then, by scanning with the laser beam scanner 18 synchronized with the reference clock signal S1, the two pulsed laser beams are irradiated to the workpiece as a parallel combined pulsed laser beam PL6 separated by a distance “Ly” in a direction orthogonal to the scanning direction. Will be.

  FIG. 8 is a schematic diagram for explaining processing and cleaning of a workpiece according to the present embodiment. As shown in FIG. 8, each of the first and second modulated pulse laser beams PL2a and PL2b generated by the first and second pulse picker operations is obtained by the first and second beam shapers. Shaped into shape. For example, the beam diameter of the second modulated pulse laser beam is adjusted to be larger than the beam diameter of the first modulated pulse laser beam.

  Irradiation / non-irradiation (ON / OFF) of the first and second modulated pulse laser beams PL2a and PL2b is controlled independently of each other. Further, the two outputs are adjusted by the first and second attenuators, for example, adjusted so that the second pulse laser beam is smaller than the first pulse laser beam, and are combined by the multiplexer 40. .

  The combined pulsed laser beam PL5 generated in this way is two parallel pulsed laser beams separated by a distance “Ly” perpendicular to the scanning direction on the workpiece. Then, for example, the second pulse on the workpiece is controlled by the control of the beam diameter by the first or second beam shaper and the control of the laser output by the control of the first or second attenuator as described above. The energy density of the laser beam is set lower than the energy density of the first pulse laser beam on the workpiece.

  With the second pulse laser beam for cleaning, debris generated by the processing by the first pulse laser beam is removed from the surface of the workpiece by laser annealing.

  Here, it is desirable that the energy density of the second pulse laser beam for cleaning is set to a limit at which the shape of the workpiece does not change. This is for suppressing deformation of the pattern due to cleaning.

  Then, as shown in FIG. 8, irradiation / non-irradiation (on / off) of the first and second pulse laser beams is controlled independently, so that the pattern of the workpiece can be obtained by one scan. Processing and cleaning of the surface of the workpiece can be performed simultaneously.

  The parallel combined pulse laser beam PL5 is irradiated to a predetermined position of the workpiece W by scanning in the X-axis direction by the laser beam scanner and movement of the workpiece W position in the Y-axis direction by the XY stage unit 20 to be processed. Fine processing and cleaning of the surface of the object W can be performed with high accuracy.

  Next, pulse picker operation data for each layer, that is, the number of processing (cleaning) pulses, the number of non-processing (non-cleaning) pulses, and the number of standby length pulses will be described. FIG. 9 is a diagram showing an example of processing by the pulse laser processing apparatus of the present embodiment. FIG. 10 is a diagram showing scanning in a specific one-dimensional direction in the processing of FIG. FIG. 11 is a diagram showing two-dimensional processing for a specific layer in the processing of FIG.

As shown in FIG. 9, for example, at intervals of _{X 1} to X-axis direction, the X-axis direction length 5 * Xp (Xp pulse interval), Y-axis direction length 3 * Yp (Yp pulse interval) Suppose that three pockets of depth Dp are formed. The length and spacing X ₁ pocket machining pulses is controlled by the non-processing pulses.

Further, at intervals of Y ₁ to Y-axis direction, and it is formed by three in the X direction. In this processing example, a total of nine pockets are formed.

  FIG. 10 shows a pulse irradiation pattern in one one-dimensional scanning. Two pulsed laser beams combined by scanning with a single laser beam scanner, that is, a first modulated pulsed laser beam for processing and a cleaning at a distance of “Ly” in a direction perpendicular to the scanning direction. Irradiation is performed by two beams of the second modulated pulse laser beam for use.

  Hereinafter, the irradiation conditions of the two beams will be described with specific examples.

Here, for the first pulse laser beam,
Beam spot diameter: D1 / e ² μm
Repetition frequency: F KHz
If scanning is performed under the following processing conditions:
Machining speed: V m / sec
When the beam irradiation position is shifted by 1 / n of the spot diameter (n is referred to as a beam irradiation movement ratio),
V = D1 / e ² × F × 10 ³ / n
It becomes.

For example, when processing Cu,
Beam spot diameter: D1 / e ² = 16 μm
Repetition frequency: F = 500KHz
Beam irradiation movement ratio: n = 2
If scanning is performed under the following processing conditions:
Processing speed: V = 4.0 m / sec
It becomes the condition of.

Also, the irradiation pulse energy Ep is
When Ep = 1 μJ / pulse, a processing depth of “0.1 μm” can be obtained, and the irradiation pulse energy density at that time is
Irradiation pulse energy density = 0.86 × Ep / A1 / e ²
Than,
Irradiation pulse energy density = 0.43 J / cm ²
It becomes.

In the case of the cleaning process using the second pulse laser beam, if the beam irradiation movement ratio is the same as that for pattern shape processing using the first pulse laser beam, the irradiation pulse energy density used for cleaning is the irradiation used for pattern shape processing. The beam spot diameter for annealing is set to about “1/10 to 1/15” of the pulse energy density,
1.2 to 1.5 × (“Y-axis shape machining travel distance”)
The cleaning process beam spot diameter and the cleaning process line unit corresponding to the N value are set.

  For example, under the above processing conditions, if the Y-axis shape processing movement distance is matched when the beam irradiation movement ratio n = 2, beam irradiation is performed every 8 μm in both the X-axis and Y-axis directions.

Here, when N = 2, the beam spot diameter for annealing is “19 to 24 μm”, and the cleaning processing unit in the Y-axis direction is 16 μm. The beam spot diameter for the cleaning process is determined in consideration of the irradiation pulse energy density.
Cleaning processing beam spot diameter: 20 μm
Irradiation pulse energy density: 0.027 J / cm ²
Set the conditions.

  Further, Lx is added to the cleaning processing range in the scanning direction from the pattern shape processing range. Further, after scanning the pattern processing end line (the twelfth scan in FIG. 9), only the cleaning process is performed in the “Ly” section for the cleaning process.

  “Lx” is an integral multiple of scanning, and “Ly” is an integral multiple of the cleaning processing unit in the Y-axis direction.

  When the line scan in the specific X direction is completed by the laser beam scanner 18 scanned only in the one-dimensional direction, the stage is moved in the Y direction orthogonal to the X direction, and further the X direction scan is performed by the laser beam scanner 18. I do. That is, the workpiece is processed by alternately repeating the scanning in the one-dimensional direction of the combined pulse laser beam by the laser beam scanner 18 and the movement of the stage in the direction orthogonal to the one-dimensional direction following this scanning.

  In this way, two-dimensional processing and cleaning for a specific layer as shown in FIG. 11 are performed. Further, two-dimensional processing is performed on another layer generated by layer decomposition by the same method as shown in FIG. Such processing for each layer is repeated to finally complete the three-dimensional pocket processing as shown in FIG.

  The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In the pulse laser processing apparatus, the pulse laser processing method, etc., the description of the parts that are not directly necessary for the explanation of the present invention is omitted, but the required pulse laser processing apparatus and the pulse laser processing method should be appropriately selected and used. Can do. In addition, all pulse laser processing apparatuses and pulse laser processing methods that include the elements of the present invention and that can be appropriately modified by those skilled in the art are included in the scope of the present invention.

  Further, for example, in the embodiment, the case of processing a pocket has been described as an example. However, the present invention is not limited to these shapes. For example, a dimple for a microlens mold and a rib for electronic paper are manufactured. It may be a pulse laser processing apparatus or a pulse laser processing method for processing a conical shape, an arbitrary shape such as a triangular pyramid, a square pyramid, a V groove, a concave groove, an R groove, or a combination thereof.

  Moreover, although Cu material was demonstrated to the example as a to-be-processed object, materials, such as metal materials, such as Ni material and SKD11, DLC material, a polymeric material, a semiconductor material, and a glass material, can also be used.

Further, the laser oscillator is not limited to the YAG laser, but is a single wavelength band laser such as a second harmonic (wavelength: 532 nm) of other Nd: YVO ₄ laser suitable for processing a workpiece. Or you may output a multiple wavelength band laser.

  In the embodiment, the case where the number of laser oscillators is one and the first pulse laser beam and the second pulse laser beam are generated by demultiplexing has been described as an example. This configuration is desirable from the viewpoint of simplifying the device configuration and reducing the device cost. However, in order to increase the output or optimize the output of each pulse laser beam, a configuration including two laser oscillators may be used.

DESCRIPTION OF SYMBOLS 10 Pulse laser processing apparatus 11 Processing data input part 12 Laser oscillator 14a 1st pulse picker 14b 2nd pulse picker 17a 1st attenuator 17b 2nd attenuator 18 Laser beam scanner 20 XY stage part 22a 1st pulse picker control Unit 22b second pulse picker control unit 24 processing control unit 26 reference clock oscillation circuit 38 duplexer 40 multiplexer 50 processing pattern division unit 52 frequency divider 54 processing pattern generation unit

Claims (10)

A reference clock oscillation circuit for generating a clock signal;
A first pulse picker that switches between passing and blocking a first pulse laser beam for processing a workpiece in synchronization with the clock signal in synchronization with the clock signal;
A second pulse picker that switches between passing and blocking a second pulse laser beam for cleaning a workpiece synchronized with the clock signal in synchronization with the clock signal;
A first pulse picker controller that controls the first pulse picker based on the number of light pulses of the first pulse laser beam;
A second pulse picker controller for controlling the second pulse picker independently of the first pulse picker based on the number of optical pulses of the second pulse laser beam;
A first attenuator provided at a subsequent stage of the first pulse picker and for adjusting an output of the first pulse laser beam;
A second attenuator provided at a subsequent stage of the second pulse picker and for adjusting an output of the second pulse laser beam;
A multiplexer provided at a stage subsequent to the first attenuator and the second attenuator, for combining the first pulse laser beam and the second pulse laser beam to generate a combined pulse laser beam;
A laser beam scanner that scans the combined pulsed laser beam only in a one-dimensional direction in synchronization with the clock signal;
A stage on which a workpiece can be placed and moves in a direction perpendicular to the one-dimensional direction;
With
The multiplexer multiplexes in a state where the optical axis of the first pulse laser beam and the optical axis of the second pulse laser beam are separated in a direction perpendicular to the one-dimensional direction;
A pulse laser processing apparatus, wherein an energy density of the second pulse laser beam on the workpiece is set lower than an energy density of the first pulse laser beam on the workpiece.   The pulse laser processing apparatus according to claim 1, wherein the stage moves in a direction orthogonal to the one-dimensional direction based on a scanning angle signal from the laser beam scanner. A laser oscillator that emits a basic pulse laser beam synchronized with the clock signal; a duplexer that demultiplexes the basic pulse laser beam into the first pulse laser beam and the second pulse laser beam;
The pulse laser processing apparatus according to claim 1, further comprising: A first beam shaper that shapes the shape of the first pulsed laser beam; a second beam shaper that shapes the shape of the second pulsed laser beam;
Further comprising
4. The pulse laser processing apparatus according to claim 1, wherein the second beam shaper includes a beam diameter changing unit that changes a beam diameter of the second pulse laser beam. 5. An input unit for inputting machining data of the workpiece;
A machining pattern generator for converting the machining data into a machining pattern;
A processing pattern dividing unit that divides the processing pattern into a first sub-processing pattern for processing a workpiece and a second sub-processing pattern for cleaning the workpiece;
The first pulse picker control unit controls the first pulse picker based on the first sub-machining pattern;
5. The pulse laser processing according to claim 1, wherein the second pulse picker control unit controls the second pulse picker based on the second sub-processing pattern. 6. apparatus.   6. The pulse laser machining apparatus according to claim 5, wherein the first and second sub machining patterns are machining tables described by the number of light pulses of a pulse laser beam.   7. The laser beam scanner is constituted by a galvanometer scanner, and the pulse picker is constituted by an acousto-optic element (AOM) or an electro-optic element (EOM). The pulse laser processing apparatus described in 1. Place the work piece on the stage,
Generate a clock signal,
Based on the number of light pulses of the first pulse laser beam for processing a workpiece synchronized with the clock signal, switching between irradiation and non-irradiation of the first pulse laser beam in synchronization with the clock signal,
Based on the number of optical pulses of the second pulse laser beam for cleaning the workpiece synchronized with the clock signal, the first pulse laser beam is irradiated and not irradiated independently of the first pulse laser beam in synchronization with the clock signal. Switch between irradiation and non-irradiation of 2 pulse laser beam,
Combining the first pulse laser beam and the second pulse laser beam to generate a combined pulse laser beam;
The combined pulse laser beam is scanned on the workpiece surface in a one-dimensional direction by a laser beam scanner in synchronization with the clock signal,
After scanning the combined pulsed laser beam in the one-dimensional direction, the stage is moved in a direction orthogonal to the one-dimensional direction, and the combined pulsed laser beam is moved in the one-dimensional direction in synchronization with the clock signal. A pulse laser processing method for scanning in a direction,
The first pulse laser beam and the second pulse laser beam are combined with each optical axis being separated in a direction perpendicular to the one-dimensional direction,
An energy density of the second pulsed laser beam on the workpiece is lower than an energy density of the first pulsed laser beam on the workpiece;
A pulse laser processing method comprising: processing the workpiece with the first pulse laser beam; and cleaning the workpiece with the second pulse laser beam.   9. The pulse laser processing method according to claim 8, wherein the stage moves in a direction orthogonal to the one-dimensional direction based on a scanning angle signal from the laser beam scanner. The pulse laser processing method according to claim 9, wherein a beam diameter of the second pulse laser beam is made larger than a beam diameter of the first pulse laser beam.

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