Laser processing apparatus, methods of operating the same, and methods of processing workpieces using the same

Abstract

To provide methods of forming vias in workpieces such as printed circuit boards.SOLUTION: Some embodiments relate to techniques for indirectly ablating a region of an electrical conductor structure of a printed circuit board by spatially distributing laser energy throughout the region of the electrical conductor structure before the electrical conductor structure is indirectly ablated. Other embodiments relate to techniques for temporally dividing laser pulses and modulating the optical power within laser pulses, and the like.SELECTED DRAWING: Figure 1

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 859,572, filed June 10, 2019, U.S. Provisional Patent Application No. 62 / 930,287, filed November 4, 2019, U.S. Provisional Patent Application No. 62 / 970,648, filed February 5, 2020, and U.S. Provisional Patent Application No. 63 / 026,564, filed May 18, 2020, each of which is incorporated by reference in its entirety. BACKGROUND

[0002] I.Technical field SUMMARY OF THE DISCLOSURE Embodiments of the present invention relate to an apparatus and method for laser processing a workpiece.

[0003] II. Description of Related Art Laser processes are often used to form blind and through vias (typically less than 150 μm in diameter) in workpieces such as printed circuit boards (both different types of rigid and flexible). Laser processes that may be used to form vias are the so-called "punch" process, the "trepan" process, or a combination of these. During a punch process, a laser energy beam is directed at a workpiece that is held stationary while the via is formed. In contrast, during a trepan process, the laser energy beam is moved relative to the workpiece to form the via. Traditionally, during a trepan process, the laser energy beam is moved to scan a helical or circular pattern over a spot that is projected on the workpiece by the laser energy beam. Overview

[0004] One embodiment may be characterized as a method of forming a feature in a workpiece including a first structure and a second structure, the feature including an opening formed in the first structure. In the method, a laser energy beam may be scanned onto the workpiece such that the laser energy beam is incident on the first structure and sequentially irradiates a plurality of spatially distinct spots in a scan pattern with the laser energy. The scanning may include: a) irradiating at least two of the plurality of spatially distinct spot locations with the laser energy to distribute the laser energy within a region of the workpiece where the feature is to be formed; and b) after a), irradiating at least two of the plurality of spatially distinct spot locations with the laser energy to indirectly ablate the first structure within the region to form the opening.

[0005] Another embodiment may be characterized as an apparatus for forming a feature in a workpiece including a first structure and a second structure. The feature includes an opening formed in the first structure. The apparatus may include a laser source capable of generating a beam of laser energy propagating along a beam path incident on the first structure of the workpiece, a positioner capable of deflecting the beam path, and a controller communicatively coupled to the positioner. The controller may be configured to control operation of the positioner to perform the scanning process described in the paragraph above.

[0006] Yet another embodiment may be characterized as an apparatus including a laser source, an acousto-optic deflector (AOD) system, and a controller. The laser source is capable of generating a laser energy beam having at least one laser pulse, the laser energy beam being capable of propagating along a beam path to a workpiece. The AOD system is capable of deflecting the beam path and includes a first AOD capable of deflecting the beam path along a first axis in response to an applied first RF signal. The controller is communicatively coupled to the AOD system and configured to control operation of the AOD system, whereby a frequency of the first RF signal is varied at least twice to temporally split a common laser pulse incident on the AOD system into a plurality of pulse slices, the frequency of the first RF signal being varied at a rate of 20 kHz or greater.

[0007] Yet another embodiment may be characterized as an apparatus including a laser source, a first scan head having a scan lens, a second scan head having a scan lens, a positioner, and a controller. The laser source is capable of generating a laser energy beam having at least one laser pulse, the laser energy beam being capable of propagating to a workpiece along a beam path. The positioner is capable of selectively deflecting the beam path between the first scan head and the second. The controller is communicatively coupled to the positioner and configured to control operation of the positioner to temporally split a common laser pulse incident on the positioner into a plurality of pulse slices including a first set of pulse slices and a second set of pulse slices. The controller is further configured to control operation of the positioner to deflect the first pulse slice set to the first scan head and the second pulse slice set to the second scan head, wherein at least one pulse slice in the second pulse slice set is temporally between two consecutive pulse slices in the first pulse slice set. [Brief description of the drawings]

[0008] [Figure 1] 1 and 31 are schematic diagrams showing a laser processing apparatus according to an embodiment of the present invention. [Diagram 2] FIG. 2 illustrates a schematic of a multi-axis AOD system that may be incorporated into the first positioner in one embodiment. [Diagram 3-4] 3 and 4 are schematic diagrams illustrating an approach for performing pulse slicing in one embodiment. [Diagram 5] FIG. 5 is a cross-sectional view that illustrates a schematic diagram of an embodiment of a workpiece that can be machined by a laser machining apparatus. [Figure 6-7] 6 and 7 are cross-sectional schematic diagrams illustrating embodiments of features that may be formed in the workpiece described with respect to FIG. 5 using a laser processing apparatus. [Figure 8-22] Figures 8 to 22 and 24(a) are diagrams showing example embodiments of scan patterns in which a process spot irradiated by a laser energy beam irradiated onto a workpiece as described in relation to Figure 5 is scanned to form features as described in relation to Figures 6 and 7. [Figure 23] Figures 23, 24(b), 25, and 26 are micrographs of blind vias formed in a workpiece (e.g., as shown in Figure 6) when scanning a process spot along the scan patterns shown in Figures 14, 24(a), 16, and 15, respectively. In Figures 23 and 24(b), the blind vias have a diameter d of about 100 μm. In Figure 25, the blind vias have a diameter d of about 75 μm. In Figure 26, the blind vias each have a diameter d of about 180 μm. [Figure 24(a)] Figures 8 to 22 and 24(a) are diagrams showing example embodiments of scan patterns in which a process spot irradiated by a laser energy beam irradiated onto a workpiece as described in relation to Figure 5 is scanned to form features as described in relation to Figures 6 and 7. [Figure 24(b)]Figures 23, 24(b), 25, and 26 are micrographs of blind vias formed in a workpiece (e.g., as shown in Figure 6) when scanning a process spot along the scan patterns shown in Figures 14, 24(a), 16, and 15, respectively. In Figures 23 and 24(b), the blind vias have a diameter d of about 100 μm. In Figure 25, the blind vias have a diameter d of about 75 μm. In Figure 26, the blind vias each have a diameter d of about 180 μm. [Diagram 25] Figures 23, 24(b), 25, and 26 are micrographs of blind vias formed in a workpiece (e.g., as shown in Figure 6) when scanning a process spot along the scan patterns shown in Figures 14, 24(a), 16, and 15, respectively. In Figures 23 and 24(b), the blind vias have a diameter d of about 100 μm. In Figure 25, the blind vias have a diameter d of about 75 μm. In Figure 26, the blind vias each have a diameter d of about 180 μm. [Figure 26] Figures 23, 24(b), 25, and 26 are micrographs of blind vias formed in a workpiece (e.g., as shown in Figure 6) when scanning a process spot along the scan patterns shown in Figures 14, 24(a), 16, and 15, respectively. In Figures 23 and 24(b), the blind vias have a diameter d of about 100 μm. In Figure 25, the blind vias have a diameter d of about 75 μm. In Figure 26, the blind vias each have a diameter d of about 180 μm. [Figure 27] FIG. 27 is a schematic plan view of the shape of a via opening formed by scanning the process spot along the second type scan pattern. [Figure 28] FIG. 28 is a diagram illustrating an exemplary circular arrangement of spot positions that, when scanned with a laser energy beam, produces vias having elliptical openings as shown illustratively in FIG. [Figure 29] FIG. 29 is a diagram illustrating an exemplary elliptical arrangement of spot positions that, when scanned with a laser energy beam, produces vias having an opening shape that is more circular than the opening shape shown in FIG. 27 . [Diagram 30] FIG. 30 is a set of diagrams illustrating an approach for pulse slicing during the formation of blind vias in one embodiment. [Diagram 31] 1 and 31 are schematic diagrams showing a laser processing apparatus according to an embodiment of the present invention. [Figure 32-45] 32-45 are diagrams illustrating an approach for pulse slicing during the formation of various features in one embodiment. [Figure 46] 46, 48 and 49 are photomicrographs of via openings formed in one embodiment of the present invention. [Figure 47] 47, 50 and 51 show an approach for forming a via having an opening similar to that shown in FIG. [Figure 48] 46, 48 and 49 are photomicrographs of via openings formed in one embodiment of the present invention. [Figure 49] 46, 48 and 49 are photomicrographs of via openings formed in one embodiment of the present invention. [Figure 50] 47, 50 and 51 show an approach for forming a via having an opening similar to that shown in FIG. [Figure 51] 47, 50 and 51 show an approach for forming a via having an opening similar to that shown in FIG. Detailed Description

[0009] Hereinafter, examples of embodiments will be described with reference to the accompanying drawings. Unless explicitly stated, in the drawings, the sizes, positions, etc. of components, features, elements, etc. and the distances therebetween are not necessarily to scale and are exaggerated for ease of understanding. Like numbers refer to like elements throughout the drawings. Thus, the same or similar numbers may be described with reference to other drawings even if they are not mentioned or described in the corresponding drawings. Also, elements without reference numbers may be described with reference to other drawings.

[0010] The terms used in the specification are for the purpose of describing certain exemplary embodiments only and are not intended to be limiting. Unless otherwise defined, all terms (including technical and scientific terms) used in this specification have the same meaning as commonly understood by one of ordinary skill in the art. As used herein, the singular is intended to include the plural unless the content clearly indicates otherwise. Furthermore, it should be understood that the terms "comprises" and / or "comprising", when used herein, specify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Unless otherwise indicated, when a range of values ​​is described, the range includes the upper and lower limits as well as any subranges between the upper and lower limits of the range. Unless otherwise indicated, terms such as "first" and "second" are only used to distinguish elements from one another. For example, one node can be referred to as a "first node" and similarly another node can be referred to as a "second node" or vice versa.

[0011] Unless otherwise indicated, "about," "around," and the like mean that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and / or larger or smaller, as appropriate, or to reflect tolerances, conversion factors, rounding, measurement errors, and the like, and other factors known to those of skill in the art. Spatially relative terms such as "lower," "below," "lower side," "upper," and "above" may be used herein for ease of description in describing the relationship of an element or feature to another element or feature, as depicted in the figures. It should be understood that the spatially relative terms are intended to include different orientations in addition to those depicted in the figures. For example, an element described as being "lower" or "below" another element or feature would be oriented "above" the other element or feature if the object in the figure were inverted. Thus, the exemplary term "lower" may include both an upper and lower orientation. If the object is otherwise oriented (e.g., rotated 90 degrees or at another orientation), the spatially relative descriptors used herein may be interpreted accordingly.

[0012] Section headings used herein, unless specifically noted, are for organizational purposes only and should not be construed as limiting the subject matter described. It will be understood that many different forms, embodiments, and combinations are possible without departing from the spirit and teachings of the present disclosure, and the present disclosure should not be construed as being limited to the example embodiments described herein. Rather, these examples and embodiments are provided so that this disclosure will be complete and all-inclusive, and will fully convey the scope of the disclosure to those skilled in the art.

[0013] I. Overview DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments described herein generally relate to methods and apparatus for laser processing (or more simply, "machining") a workpiece. Generally, processing is accomplished in whole or in part by applying laser radiation to the workpiece to heat, melt, vaporize, ablate, scratch, bleach, polish, roughen, carbonize, foam, or otherwise modify one or more characteristics or properties (e.g., chemical composition, atomic structure, ionic structure, molecular structure, electronic structure, microstructure, nanostructure, density, viscosity, refractive index, magnetic permeability, dielectric constant, texture, color, hardness, transmissivity to electromagnetic radiation, etc., or any combination thereof) of one or more materials forming the workpiece. The material being processed may be external to the workpiece prior to or during processing, or may be entirely internal to the workpiece (i.e., not external to the workpiece) prior to or during processing.

[0014] Specific examples of processes that may be performed by the disclosed laser processing apparatus include drilling vias or forming other holes, which are described in more detail below. It will be understood that the embodiments described herein may be extended to perform or facilitate cutting, punching, welding, scribing, engraving, marking (e.g., surface marking, sub-surface marking, etc.), laser-induced forward transfer, cleaning, bleaching, repair of bright pixels (e.g., color filter darkening, OLED material modification, etc.), film removal, surface texturing (e.g., roughening, smoothing, etc.), or the like, or any combination thereof. Thus, one or more features that may be formed on or in a workpiece as a result of processing may include openings, slots, vias or other holes, grooves, trenches, scribe lines, kerfs, recesses, conductive traces, ohmic contacts, resistive patterns, human readable or machine readable indicia (e.g., comprising one or more areas in or on a workpiece having one or more visually or texturally distinct characteristics), or the like, or any combination thereof. Apertures, slots, vias, holes, etc. features may have any suitable or desirable shape in a top view (e.g., circular, oval, square, rectangular, triangular, tubular, or the like, or any combination thereof). Furthermore, openings, slots, vias, holes, etc. features may extend completely through the workpiece (e.g., to form so-called "through vias", "through holes", etc.) or may extend only partially through the workpiece (to form so-called "blind vias", "blind holes", etc.).

[0015] The workpieces that may be processed may be generally characterized as being formed from one or more metals, polymers, ceramics, composites, or any combination thereof (e.g., whether alloys, compounds, mixtures, solutions, composites, etc.). Examples of workpieces specifically mentioned herein include printed circuit board (PCB) panels (also referred to herein as "PCB panels"), PCBs, flexible printed circuits (FPCs), integrated circuits (ICs), and integrated circuit packages (ICPs). However, light emitting diodes (LEDs), LED packages, semiconductor wafers, electronic or optical device substrates (e.g., Al2O3, AlN, BeO, Cu, GaAS, GaN, Ge, InP, Si, SiO2, SiC, Si 1-x Ge x or any combination thereof or any combination of alloys thereof), lead frames, lead frame blanks, plastics, unstrengthened glass, heat strengthened glass, chemically strengthened glass (e.g., via an ion exchange process), formed from quartz, sapphire, plastic, silicon, or the like, components of electronic displays (e.g., TFTs, color filters, organic light emitting diode (OLED) arrays, quantum dot LED arrays, or the like, or substrates formed with any combination thereof), lenses, mirrors, screen protectors, turbine blades, powders, films, foils, plates, molds (e.g., It will be appreciated that other types of workpieces, such as molds, patterns for injection molding or investment casting processes, textiles (woven fabrics, felt, etc.), surgical instruments, medical implants, packaged products, shoes, bicycles, automobiles, automobile or aviation parts (e.g., frames, body panels, etc.), appliances (e.g., microwave ovens, ovens, refrigerators, etc.), device housings (e.g., for watches, computers, smartphones, tablet computers, wearable electronic devices, etc., or any combination thereof), may also be beneficially machined.

[0016] Thus, materials that may be processed include one or more metals, such as Al, Ag, Au, Cu, Fe, In, Mg, Pt, Sn, Ti, and the like, or any combination thereof (e.g., whether alloyed, composite, etc.), conductive metal oxides (e.g., ITO, etc.), transparent conductive polymers, ceramics, waxes, resins, inorganic dielectric materials (e.g., used in interlayer dielectric structures, such as silicon oxide, silicon nitride, silicon oxynitride, and the like, or any combination thereof), low-k dielectric materials (methyl silsesquioxane (MSQ), hydrogen silsesquioxane (HSQ), fluorinated tetraethyl orthosilicate (FTEOS), and the like, or any combination thereof), organic dielectric materials (e.g., SILK, benzocyclobutene, Nautilus (all manufactured by Dow), polyfluorotetraethylene (manufactured by DuPont), FLARE (Allied and the like, or any combination thereof), fiberglass, polymeric materials (polyamide, polyimide, polyester, polyacetal, polycarbonate, modified polyphenylene ether, polybutylene terephthalate, polyphenylene sulfide, polyethersulfone, polyetherimide, polyetheretherketone, liquid crystal polymer, acrylonitrile butadiene styrene, or any compound, composite, or alloy thereof), leather, paper, construction materials (e.g., Ajinomoto Build-up Film, also known as "ABF"), fiberglass reinforced epoxy laminates (e.g., FR4), prepregs, solder resists, and the like, or any composite, laminate, or other combination thereof.

[0017] II. System Overview FIG. 1 is a schematic diagram of a laser processing apparatus according to an embodiment of the present invention.

[0018] 1, a laser processing apparatus 100 (also referred to herein simply as "the apparatus") for processing a workpiece 102 can be characterized as including a laser source 104 generating a beam of laser energy, a first positioner 106, a second positioner 108, a third positioner 110, and a scan lens 112. It should be noted that each of the second positioner 108, the third positioner 110, and the scan lens 112 are optional and may be omitted from the apparatus 100. The scan lens 112 and the second positioner 108 can be integrated into a common housing or "scan head" 120, if desired.

[0019] As described in more detail below, the first positioner 106 is capable of diffracting the laser energy beam in order to deflect the beam path 114 to one of the second positioners 108. As used herein, the term "beam path" refers to the path traversed by laser energy in the laser energy beam as it propagates from the laser source 104 to the scan lens 112. In deflecting the beam path 114 to the second positioner 108, the beam path 114 can be deflected at any angle (e.g., measured relative to the beam path 114 entering the first positioner 106) within a first angular range (also referred to herein as the "primary angular range 116").

[0020] The second positioner 108 may diffract, reflect, refract, or the like, or any combination thereof, of the laser energy beam generated by the laser source 104 and deflected by the first positioner 106 (i.e., to “deflect” the laser energy beam) to deflect the beam path 114 to the scan lens 112. In deflecting the beam path 114 to the scan lens 112, the second positioner 108 may deflect the beam path 114 by any angle (e.g., measured relative to the optical axis of the scan lens 112) within a second angular range (also referred to herein as a “secondary angular range 118”).

[0021] The laser energy deflected by the scan lens 112 is typically focused by the scan lens 112 to impinge on the workpiece 102 and transmitted to propagate along the beam axis. The laser energy impinging on the workpiece 102 can be characterized as having a Gaussian spatial intensity profile or a non-Gaussian (or "shaped") spatial intensity profile (e.g., a "top hat" spatial intensity profile, a super-Gaussian spatial intensity profile, etc.).

[0022] As used herein, the term "spot size" refers to the diameter or maximum spatial width of the laser energy beam impinging on a region of the workpiece 102 that is at least partially processed by the impinging laser energy beam at a location where the beam axis intersects the region (also called a "process spot," "spot location," or simply a "spot"). For purposes of this description, spot size refers to the distance from the beam axis where the optical intensity is 1 / e of the optical intensity at the beam axis. 2The spot size of the laser energy beam is measured as the radial or transverse distance down to the beam waist. Generally, the spot size of the laser energy beam is smallest at the beam waist. When applied to the workpiece 102, the laser energy in the beam can be characterized as striking the workpiece 102 with a spot size ranging from 2 μm to 200 μm. However, it will be understood that the spot size can be less than 2 μm or greater than 200 μm. Thus, the laser energy beam applied to the workpiece 102 can have a spot size greater than, less than, or equal to 2 μm, 3 μm, 5 μm, 7 μm, 10 μm, 15 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 80 μm, 100 μm, 150 μm, 200 μm, etc., or any value between these values.

[0023] The apparatus 100 may also include one or more other optical components (e.g., beam traps, beam expanders, beam shapers, beam splitters, apertures, filters, collimators, lenses, mirrors, prisms, polarizers, phase retarders, diffractive optical elements (commonly known in the art as DOEs), refractive optical elements (commonly known in the art as ROEs), and the like, or any combination thereof) to focus, expand, collimate, shape, polarize, filter, split, combine, crop, absorb, or otherwise modify, condition, etc., the laser energy beam as it propagates along the beam path 114.

[0024] A. Laser Source In one embodiment, the laser source 104 is capable of generating laser pulses. Thus, the laser source 104 may include a pulsed laser source, a CW laser source, a QCW laser source, a burst mode laser, etc., or any combination thereof. When the laser source 104 includes a QCW or CW laser source, the laser source 104 may operate in a pulsed mode, or may operate in a non-pulsed mode, but may further include a pulse gating unit (e.g., an acousto-optic (AO) modulator (AOM), a beam chopper, etc.) that temporally modulates the beam of laser radiation output from the QCW or CW laser source. Although not shown, the apparatus 100 may optionally include one or more harmonic generating crystals (also known as "wavelength conversion crystals") configured to convert the wavelength of the light output by the laser source 104. However, in other embodiments, the laser source 104 may be provided as a QCW or CW laser source and may not include a pulse gating unit. As such, the laser source 104 may be broadly characterized as capable of generating a beam of laser energy, which may be represented as a series of laser pulses, or as a continuous or quasi-continuous laser beam, which may then propagate along the beam path 114. Although many of the embodiments described herein refer to laser pulses, it should be understood that a continuous or quasi-continuous beam may alternatively or additionally be used where appropriate or desired.

[0025] The laser energy output by the laser source 104 may have one or more wavelengths in the ultraviolet (UV), visible, or infrared (IR) portions of the electromagnetic spectrum. Laser energy in the UV portion of the electromagnetic spectrum may have one or more wavelengths in the range of 10 nm (or thereabouts) to 385 nm (or thereabouts), such as 100 nm, 121 nm, 124 nm, 157 nm, 200 nm, 334 nm, 337 nm, 351 nm, 380 nm, etc., or any wavelength between these values. Laser energy in the visible green portion of the electromagnetic spectrum may have one or more wavelengths in the range of 500 nm (or thereabouts) to 560 nm (or thereabouts), such as 511 nm, 515 nm, 530 nm, 532 nm, 543 nm, 568 nm, etc., or any wavelength between these values. Laser energy in the IR region of the electromagnetic spectrum may have one or more wavelengths in the range of 750 nm (or thereabouts) to 15 μm (or thereabouts), such as 600 nm to 1000 nm, 752.5 nm, 780 nm to 1060 nm, 799.3 nm, 980 nm, 1047 nm, 1053 nm, 1060 nm, 1064 nm, 1080 nm, 1090 nm, 1152 nm, 1150 nm to 1350 nm, 1540 nm, 2.6 μm to 4 μm, 4.8 μm to 8.3 μm, 9.4 μm, 10.6 μm, etc., or wavelengths between any of these values.

[0026] When the laser energy beam is represented as a train of laser pulses, the laser pulses output by the laser source 104 may have a pulse width or duration (i.e., based on the full width at half maximum (FWHM) of the optical power in the pulse versus time) ranging from 10 fs to 900 ms, however, it will be understood that the pulse duration may be shorter than 10 fs or longer than 900 ms. In this manner, the at least one laser pulse output by the laser source 104 may be any of the following: 10 fs, 15 fs, 30 fs, 50 fs, 100 fs, 150 fs, 200 fs, 300 fs, 500 fs, 600 fs, 750 fs, 800 fs, 850 fs, 900 fs, 950 fs, 1 ps, 2 ps, 3 ps, 4 ps, 5 ps, 7 ps, 10 ps, ​​15 ps, 25 ps, 50 ps, ​​75 ps, 100 ps, ​​200 ps, ​​500 ps, ​​1 ns, 1.5 ns, 2 ns, 5 ns, 10 ns, 20 ns, 50 ns, 10 The pulse duration may be shorter, longer, or equal to 0 ns, 200 ns, 400 ns, 800 ns, 1000 ns, 2 μs, 5 μs, 10 μs, 15 μs, 20 μs, 25 μs, 30 μs, 40 μs, 50 μs, 100 μs, 300 μs, 500 μs, 900 μs, 1 ms, 2 ms, 5 ms, 10 ms, 20 ms, 50 ms, 100 ms, 300 ms, 500 ms, 900 ms, 1 s, etc., or a value between any of these values.

[0027] The laser pulses output by the laser source 104 can have an average power in the range of 5 mW to 50 kW. However, it will be appreciated that the average power can be less than 5 mW or greater than 50 kW. Thus, the laser pulses output by the laser source 104 can have an average power less than, greater than, or equal to 5 mW, 10 mW, 15 mW, 20 mW, 25 mW, 50 mW, 75 mW, 100 mW, 300 mW, 500 mW, 800 mW, 1 W, 2 W, 3 W, 4 W, 5 W, 6 W, 7 W, 10 W, 15 W, 18 W, 25 W, 30 W, 50 W, 60 W, 100 W, 150 W, 200 W, 250 W, 500 W, 2 kW, 3 kW, 20 kW, 50 kW, etc., or any value between these values.

[0028] Laser pulses may be output by the laser source 104 at a pulse repetition rate ranging from 5 kHz to 5 GHz. However, it will be appreciated that the pulse repetition rate may be less than 5 kHz or greater than 5 GHz. Thus, laser pulses may be output by the laser source 104 at pulse repetition rates less than, greater than, or equal to 5 kHz, 50 kHz, 100 kHz, 175 kHz, 225 kHz, 250 kHz, 275 kHz, 500 kHz, 800 kHz, 900 kHz, 1 MHz, 1.5 MHz, 1.8 MHz, 1.9 MHz, 2 MHz, 2.5 MHz, 3 MHz, 4 MHz, 5 MHz, 10 MHz, 20 MHz, 50 MHz, 60 MHz, 100 MHz, 150 MHz, 200 MHz, 250 MHz, 300 MHz, 350 MHz, 500 MHz, 550 MHz, 600 MHz, 900 MHz, 2 GHz, 10 GHz, etc., or any value between these values.

[0029] In addition to wavelength, average power, and, if the laser energy beam is represented as a series of laser pulses, pulse duration and pulse repetition rate, the laser energy beam irradiated to the workpiece 102 may be characterized by one or more other characteristics, such as pulse energy, peak power, etc. Such characteristics may include the optical intensity (W / cm2) sufficient to process the workpiece 102 (e.g., to form one or more features). 2 (measured in J / cm2) and fluence (J / cm2) 2 The laser beam may be selected (e.g., based on one or more other characteristics, such as wavelength, pulse duration, average power, pulse repetition rate, spot size, etc., as desired) to irradiate a process spot on the workpiece 102 to process the workpiece 102 (e.g., form one or more features), such as measured by a laser beam splitter (e.g., laser light source) at a wavelength of 100 nm, a laser beam splitter (e.g., laser light source), a laser light source ...

[0030] Examples of types of lasers that may characterize the laser source 104 include gas lasers (e.g., carbon dioxide lasers, carbon monoxide lasers, excimer lasers, etc.), solid state lasers (e.g., Nd:YAG lasers, etc.), rod lasers, fiber lasers, photonic crystal rod / fiber lasers, passively mode-locked solid bulk or fiber lasers, dye lasers, mode-locked diode lasers, pulsed lasers (e.g., ms pulsed lasers, ns pulsed lasers, ps pulsed lasers, fs pulsed lasers), CW lasers, QCW lasers, etc., or any combination thereof. In some configurations, gas lasers (e.g., carbon dioxide lasers, etc.) may be configured to operate in one or more modes (e.g., CW mode, QCW mode, pulsed mode, or any combination thereof). Specific examples of laser sources that may be provided as laser source 104 include BOREAS, HEGOA, SIROCCO, or CHINOOK series lasers manufactured by EOLITE, PYROFLEX series lasers manufactured by PYROPHOTONICS, PALADIN Advanced 355 or DIAMOND series (e.g., DIAMOND E series, G series, J-2 series, J-3 series, J-5 series), FLARE NX series, MATRIX QS DPSS series, MEPHISTO Q series, AVIA LX series, AVIA NX series, RAPID NX series, HYPERRAPID NX series, RAPID series, HELIOS series, FIDELITY series, MONACO series, OPERA series, or RAPID FX series lasers manufactured by COHERENT, SPECTRA ASCEND series, EXCELSIOR series, EXPLORER series, FEMTOTRAIN series, HIGHQ-2 series, HIPPO series, ICEFYRE series, NAVIGATOR series, QUANTA-RAY series, QUASAR series, and SOLSTICS manufactured by PHYSICS.ACE series, SPIRIT series, TALON series, VANGUARD series, or VGEN series lasers, PULSTAR series or FIRESTAR series lasers manufactured by SYNRAD, TRUFLOW series lasers (e.g., TRUFLOW 2000, 2600, 3000, 3200, 3600, 4000, 5000, 6000, 8000, 10000, 12000, 15000, 20000), TRUCOAX series lasers (e.g., TRUCOAX 1000), TRUDISK series, TRUPULSE series, TRUDIODE series, TRUFIBER series, or TRUMICRO series lasers, FCPAμJEWEL or FEMTOLITE series lasers manufactured by IMRA AMERICA, AMPLITUDE TANGERINE and SATSUMA series lasers (and MIKAN and T-PULSE series oscillators) manufactured by IPG SYSTEMES, CL series, CLPF series, CLPN series, CLPNT series, CLT series, ELM series, ELPF series, ELPN series, ELPP series, ELR series, ELS series, FLPN series, FLPNT series, FLT series, GLPF series, GLPN series, GLR series, HLPN series, HLPP series, RFL series, TLM series, TLPN series, TLR series, ULPN series, ULR series, ULM series manufactured by IPG PHOTONICS The laser source may include one or more laser sources such as a laser from the VLM series, VLPN series, YLM series, YLPF series, YLPN series, YLPP series, YLR series, YLS series, FLPM series, FLPMT series, DLM series, BLM series, or DLR series of lasers (including, for example, GPLN-532-100-M, GPLN-532-200, GPLN-532-500, ULR / ULM-355-200, etc.), or the like, or any combination thereof.

[0031] B. First Positioner In general, the first positioner 106 is capable of moving the beam axis relative to the workpiece 102 along the X-axis (or X-direction), the Y-axis (or Y-direction), or a combination thereof (e.g., by deflecting the beam path 114 within a first primary angular range 116). Although not shown, the Y-axis (or Y-direction) will be understood to mean an axis (or direction) that is orthogonal to the illustrated X-axis (or X-direction) and Z-axis (or Z-direction).

[0032] Beam axis movement by the first positioner 106 relative to the workpiece 102 is generally limited to scan, move, or position a process spot within a first scan area projected by the scan lens 112. In general, depending on one or more factors such as the configuration of the first positioner 106, the location of the first positioner 106 along the beam path 114, and the beam size of the laser energy beam incident on the first positioner 106, the first scan area may extend in either the X or Y direction to a distance less than, greater than, or equal to 0.01 mm, 0.04 mm, 0.1 mm, 0.5 mm, 1.0 mm, 1.4 mm, 1.5 mm, 1.8 mm, 2 mm, 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, 4.2 mm, 5 mm, 10 mm, 25 mm, 50 mm, 60 mm, etc., or any value between these values. As used herein, the term “beam size” refers to the diameter or width of the laser energy beam, the diameter or width from the beam axis where the optical intensity is 1 / e of the optical intensity at the axis of propagation along the beam path 114. 2 The maximum dimension of the first scan area (e.g., in a plane containing the X-axis and Y-axis (herein referred to as the “XY plane”)) may be greater than, equal to, or less than a corresponding maximum dimension (measured in the XY plane) of a feature (e.g., an opening, recess, via, trench, etc.) to be formed in the workpiece 102.

[0033] Generally, the first positioner 106 is provided as an AO deflector (AOD) system that includes one or more AODs having AO cells formed from materials such as crystalline germanium (Ge), gallium arsenide (GaAs), pyrite (PbMoO4), tellurium dioxide (TeO2), quartz, vitreous SiO2, arsenic trisulfide (As2S3), lithium niobate (LiNbO3), or the like, or any combination thereof. In one embodiment, the AOD system includes at least one (e.g., 1, 2, 3, 4, 5, 6, etc.) single element AOD, at least one (e.g., 1, 2, 3, 4, 5, 6, etc.) multi-element AOD, or the like, or any combination thereof. As used herein, an AOD system that includes only one AOD is referred to as a "single-cell AOD system" and an AOD system that includes more than one AOD is referred to as a "multi-cell AOD system." As used herein, a "single-element" AOD means an AOD with only one ultrasonic transducer element acoustically coupled to an AO cell, and a "multi-element" AOD includes two or more ultrasonic transducer elements acoustically coupled to a common AO cell. An AOD system can be provided as a single-axis AOD system (e.g., a beam axis can be deflected along a single axis) or as a multi-axis AOD system (e.g., a beam axis can be deflected along one or more axes, such as along an X-axis or along a Y-axis, or along any combination thereof) by deflecting the beam path 114 in a corresponding manner. In general, a multi-axis AOD system can be provided as a single-cell AOD system or a multi-cell AOD system. A multi-cell multi-axis AOD system typically includes multiple AODs, each capable of deflecting a beam axis along a different axis. For example, a multi-cell, multi-axis system may include a first AOD (e.g., a single element or multi-element AOD system) capable of deflecting a beam axis along one axis (e.g., along the X axis) and a second AOD (e.g., a single element or multi-element AOD) capable of deflecting a beam axis along a second axis (e.g., along the Y axis).A single-cell multi-axis system typically includes a single AOD capable of deflecting a beam axis along two axes (e.g., along the X and Y axes). For example, a single-cell multi-axis system may include two or more ultrasonic transducer elements acoustically coupled to orthogonally arranged planes, facets, sides, etc. of a common AO cell.

[0034] As will be appreciated by those skilled in the art, AO technologies (e.g., AODs, AOMs, etc.) utilize the diffraction effect caused by one or more acoustic waves propagating through the AO cell (along the "diffraction axis" of the AOD) to diffract an incident light wave (i.e., in the context of this application, a laser energy beam) that is simultaneously propagating through the AO cell (along the "optical axis" within the AOD). Diffraction of the incident laser energy beam produces a diffraction pattern that typically includes zero and first order diffraction peaks, and may also include other diffraction peaks of higher orders (e.g., second order, third order, etc.). As is known in the art, the portion of the laser energy beam diffracted at the zero order diffraction peak is referred to as the "zero order" beam, the portion of the laser energy beam diffracted at the first order diffraction peak is referred to as the "first order" beam, and so on. Generally, the zero order beam and other order beams (e.g., first order beam, etc.) propagate along different beam paths as they exit the AO cell (e.g., through the optical output side of the AO cell). For example, the zero order beam propagates along a zero order beam path, the first order beam propagates along a first order beam path, and so on.

[0035] Acoustic waves are typically input to the AO cell by applying an RF drive signal (e.g., from one or more drivers of the first positioner 106) to the ultrasonic transducer elements. The characteristics (e.g., amplitude, frequency, phase, etc.) of the RF drive signal can be controlled (e.g., based on one or more control signals output by the controller 122, a component-specific controller, etc., or any combination thereof) to adjust the way in which the incident optical waves are diffracted. For example, the frequency of a given RF drive signal determines the angle by which the beam path 114 is deflected. As is known in the art, the angle Θ by which the beam path 114 is deflected can be calculated as follows:

number

[0036] The first beam path exiting the AO cell can typically be considered as the beam path 114 rotated or deflected within the AO cell. Unless otherwise indicated herein, the beam path 114 exiting the AO cell corresponds to the first beam path. The axis (also referred to herein as the “rotation axis”) about which the beam path 114 exiting the AO cell is rotated (e.g., relative to the beam path 114 as it entered the AO cell) is orthogonal to both the diffraction axis of the AO cell and the optical axis along which the incident laser energy beam propagates within the AO cell when the AOD is operated or driven to diffract the incident laser energy beam. Thus, the AOD deflects the incident beam path 114 within a plane (also referred to herein as the “deflection plane”) that includes (or is otherwise substantially parallel to) the diffraction axis of the AO cell and the optical axis within the AO cell. The spatial extent over which the AOD can deflect the beam path 114 within the deflection plane is referred to herein as the “scan region” of the AOD. Thus, the first scan area of ​​the first positioner 106 can be considered to correspond to the scan area of ​​a single AOD (e.g., if the first positioner 106 includes a single AOD), or can be considered to correspond to the combined scan area of ​​the multiple AODs (e.g., if the first positioner 106 includes multiple AODs).

[0037] The first positioner 106 can be characterized as having a "first positioning speed," which refers to the speed at which the first positioner 106 positions (and thereby moves the beam axis) the process spot to any location within the first scan region. For example, the first positioning speed can be greater than or less than 8 kHz, 10 kHz, 20 kHz, 30 kHz, 40 kHz, 50 kHz, 75 kHz, 80 kHz, 100 kHz, 250 kHz, 500 kHz, 750 kHz, 1 MHz, 5 MHz, 10 MHz, 20 MHz, 40 MHz, 50 MHz, 75 MHz, 100 MHz, 125 MHz, 150 MHz, 175 MHz, 200 MHz, 225 MHz, 250 MHz, etc., or a value between any of these values. This range is also referred to herein as the first positioning bandwidth. During operation of the first positioner 106, an RF drive signal is repeatedly applied to one or more ultrasonic transducers of the first positioner 106, and the first positioning bandwidth corresponds to (e.g., is equal to, or at least substantially equal to) the rate at which the RF drive signal is applied. The rate at which the RF drive signal is applied is also referred to as the "update rate" or "refresh rate." As used herein, the inverse of the first positioning rate is referred to as the "first positioning period" and refers to the shortest time it takes for the position of the process spot to change from one location within the first scan area to another location within the first scan area. Thus, the first positioner 106 can be characterized as having a first positioning period that is greater than or less than 200 μs, 125 μs, 100 μs, 50 μs, 33 μs, 25 μs, 20 μs, 15 μs, 13.3 μs, 12.5 μs, 10 μs, 4 μs, 2 μs, 1.3 μs, 1 μs, 0.2 μs, 0.1 μs, 0.05 μs, 0.025 μs, 0.02 μs, 0.013 μs, 0.01 μs, 0.008 μs, 0.0067 μs, 0.0057 μs, 0.0044 μs, 0.004 μs, etc., or a value between any of these values.

[0038] It will be appreciated that the materials forming the AO cell will depend on the wavelength of the laser energy propagating along the beam path 114 to be incident on the AO cell. For example, if the wavelength of the deflected laser energy is in the range of 2 μm (or thereabouts) to 20 μm (or thereabouts), materials such as crystalline germanium can be used, if the wavelength of the deflected laser energy is in the range of 1 μm (or thereabouts) to 11 μm (or thereabouts), materials such as gallium arsenide and arsenic trisulfide can be used, and if the wavelength of the deflected laser energy is in the range of 200 nm (or thereabouts) to 5 μm (or thereabouts), materials such as vitreous SiO2, quartz, lithium niobate, pyrite, and tellurium dioxide can be used.

[0039] When the laser energy beam output by the laser source 104 is represented as a series of laser pulses, the first positioner 106 can be operated to change the beam path 114 at different angles within the primary angular range 116. In one embodiment, the first positioning period is equal to or greater than the pulse duration of each of the laser pulses. Thus, the laser pulses are transmitted through the AO cell of the AOD when the AOD is driven at a fixed RF drive frequency (or a set of fixed RF drive frequencies). By maintaining a fixed RF drive frequency (or a set of fixed RF drive frequencies) on the AOD when the laser pulses are transmitted through the AO cell of the AOD, the laser pulses can generally be deflected uniformly over the entire pulse duration of the laser pulse, which may also be referred to as "full pulse deflection". However, in other embodiments, the first positioning period may be shorter than the pulse duration of the laser pulse, which may allow the laser pulses to be transmitted through the AO cell of the AOD when the RF drive frequency (or a frequency within the set of RF drive frequencies) is being changed. By varying the RF drive frequency provided to the AOD as the laser pulse passes through the AO cell of the AOD, the laser pulse can be split in time, which is sometimes referred to as "partial pulse deflection" or "pulse slicing." Aspects of pulse slicing are described in more detail below. Although pulse slicing techniques are applied herein to split laser pulses in time, it will be understood that these techniques may similarly be applied to split in time any beam of laser energy represented as a continuous or quasi-continuous laser beam.

[0040] C. Second Positioner In general, the second positioner 108 can move the beam axis relative to the workpiece 102 along the X-axis (or X-direction), the Y-axis (or Y-direction), or a combination thereof (e.g., by deflecting the beam path 114 within a first secondary angular range 118a or a second secondary angular range 118b).

[0041] Beam axis movement by the second positioner 108 relative to the workpiece 102 is generally limited to scan, move, or position a process spot within a second scan area projected by the scan lens 112. In general, the second scan area may extend a greater distance in either the X or Y direction than the corresponding distance of the first scan area, depending on one or more factors such as the configuration of the second positioner 108, the location of the second positioner 108 along the beam path 114, the beam size of the laser energy beam incident on the second positioner 108, and the spot size. In view of the above, the second scan area may extend in either the X or Y direction to a distance less than, greater than, or equal to 1 mm, 25 mm, 50 mm, 75 mm, 100 mm, 250 mm, 500 mm, 750 mm, 1 cm, 25 cm, 50 cm, 75 cm, 1 m, 1.25 m, 1.5 m, etc., or any value between these values. The maximum dimension of the second scan area (e.g., in the XY plane) may be greater than, equal to, or less than the maximum dimension (measured in the XY plane) of a feature (e.g., opening, recess, via, trench, scribe line, conductive trace, etc.) formed in the workpiece 102.

[0042] In view of the configurations described herein, the beam axis movement performed by the first positioner 106 can be superimposed on the beam axis movement performed by the second positioner 108. Thus, the second positioner 108 can scan the first scan area within the second scan area.

[0043] In general, the positioning speed at which the second positioner 108 can position the process spot anywhere within the second scan region (thereby moving the beam axis within the second scan region and / or scanning the first scan region within the second scan region) ranges less than the first positioning bandwidth (also referred to herein as the "second positioning bandwidth"). In one embodiment, the second positioning bandwidth ranges from 500 Hz (or thereabouts) to 8 kHz (or thereabouts). For example, the second positioning bandwidth may be greater than, equal to, or less than 500 Hz, 750 Hz, 1 kHz, 1.25 kHz, 1.5 kHz, 1.75 kHz, 2 kHz, 2.5 kHz, 3 kHz, 3.5 kHz, 4 kHz, 4.5 kHz, 5 kHz, 5.5 kHz, 6 kHz, 6.5 kHz, 7 kHz, 7.5 kHz, 8 kHz, etc., or any value between these values.

[0044] In one embodiment, the second positioner 108 may be provided as a galvanometer mirror system including two galvanometer mirror components, a first galvanometer mirror component (e.g., an X-axis galvanometer mirror component) configured to move the beam axis along the X-axis relative to the workpiece 102, and a second galvanometer mirror component (e.g., a Y-axis galvanometer mirror component) configured to move the beam axis along the Y-axis relative to the workpiece 102. However, in other embodiments, the second positioner 108 may be provided as a galvanometer mirror system including only a single galvanometer mirror component configured to move the beam axis along the X-axis and the Y-axis relative to the workpiece 102. In yet other embodiments, the second positioner 108 may be provided as a rotating polygon mirror system, or the like. Thus, it will be appreciated that depending on the particular configuration of the second positioner 108 and the first positioner 106, the second positioning bandwidth may be greater than or equal to the first positioning bandwidth.

[0045] D. Third Positioner The third positioner 110 can move the workpiece 102 (e.g., workpieces 102a and 102b) relative to the scan lens 112, which can result in the movement of the workpiece 102 relative to the beam axis. The movement of the workpiece 102 relative to the beam axis is generally limited to allow the process spot to be scanned, moved, or positioned within the third scan area. Depending on one or more factors, such as the configuration of the third positioner 110, the third scan area may extend in the X direction, the Y direction, or any combination thereof, to a distance greater than or equal to the corresponding distance of the second scan area. However, in general, the maximum dimension of the third scan area (e.g., in the XY plane) is greater than or equal to the corresponding maximum dimension (measured in the XY plane) of the feature formed on the workpiece 102. If desired, the third positioner 110 may be capable of moving the workpiece 102 relative to the beam axis within a scan region extending in the Z direction (e.g., over a range of 1 mm to 50 mm). Thus, the third scan region may extend along the X, Y, and / or Z directions.

[0046] It should be understood that in view of the configurations described herein, the movement of the process spot relative to the workpiece 102 (e.g., by the first positioner 106 and / or the second positioner 108) can be superimposed on the movement of the workpiece 102 by the third positioner 110. Thus, the third positioner 110 can scan the first scan area and / or the second scan area within the third scan area. In general, the positioning speed at which the third positioner 110 can position the workpiece 102 anywhere within the third scan area (thereby moving the workpiece 102 to scan the first scan area within the third scan area and / or scan the second scan area within the third scan area) ranges less than the second positioning bandwidth (also referred to herein as the "third positioning bandwidth"). In one embodiment, the third positioning bandwidth is less than 500 Hz (or about). For example, the third positioning bandwidth may be equal to or lower than 500Hz, 250Hz, 150Hz, 100Hz, 75Hz, 50Hz, 25Hz, 10Hz, 7.5Hz, 5Hz, 2.5Hz, 2Hz, 1.5Hz, 1Hz, etc., or a value between any of these values.

[0047] In one embodiment, the third positioner 110 is provided as one or more linear stages (e.g., capable of imparting translational movement to the workpiece 102 along the X-, Y-, and / or Z-directions, respectively), one or more rotational stages (e.g., capable of imparting rotational movement to the workpiece 102 about axes parallel to the X-, Y-, and / or Z-directions, respectively), or any combination thereof. In one embodiment, the third positioner 110 includes an X-stage for moving the workpiece 102 along the X-direction, and a Y-stage supported by the X-stage (and thereby movable along the X-direction by the X-stage) for moving the workpiece 102 along the Y-direction.

[0048] As previously discussed, the apparatus 100 may use a so-called “stacked” positioning system for the third positioner 110, which allows the workpiece 102 to be moved while the positions of other components, such as the first positioner 106, the second positioner 108, the scan lens 112, etc., remain stationary within the apparatus 100 relative to the workpiece 102 (e.g., via one or more supports, frames, etc., as known in the art). In other embodiments, the third positioner 110 may be arranged and operated to move one or more components, such as the first positioner 106, the second positioner 108, the scan lens 112, etc., or any combination thereof, and the workpiece 102 may remain stationary.

[0049] In yet other embodiments, the third positioner 110 may be provided as a so-called "split-axis" positioning system, in which one or more components, such as the first positioner 106, the second positioner 108, the scan lens 112, etc., or any combination thereof, are carried by one or more linear or rotary stages (e.g., mounted on a frame, gantry, etc.), and the workpiece 102 is carried by one or more other linear or rotary stages. In such embodiments, the third positioner 110 includes one or more linear or rotary stages positioned and operable to move one or more components, such as the scan head (e.g., including the second positioner 108 and the scan lens 112), and one or more linear or rotary stages positioned and operable to move the workpiece 102. For example, the third positioner 110 may include a Y stage to move the workpiece 102 along a Y direction and an X stage to move the scan head along an X direction. Examples of split-axis positioning systems that may be beneficially or advantageously utilized in apparatus 100 include any of those disclosed in U.S. Patent Nos. 5,751,585, 5,798,927, 5,847,960, 6,606,999, 7,605,343, 8,680,430, 8,847,113, or in U.S. Patent Application Publication No. 2014 / 0083983, each of which is incorporated herein by reference in its entirety.

[0050] In one embodiment in which the third positioner 110 includes a Z stage, the Z stage may be positioned and configured to move the workpiece 102 along the Z direction. In this case, the Z stage may be carried by or may carry one or more of the other stages described above for moving or positioning the workpiece 102, or any combination thereof. In another embodiment in which the third positioner 110 includes a Z stage, the Z stage may be positioned and configured to move the scan head along the Z direction. Thus, when the third positioner 110 is provided as a split-axis positioning system, the Z stage may carry or be carried by the X stage. Moving the workpiece 102 or the scan head along the Z direction can change the spot size at the workpiece 102.

[0051] In yet other embodiments, one or more components, such as the first positioner 106, the second positioner 108, and the scan lens 112, may be carried by a multi-axis articulated robot arm (e.g., a two-axis, three-axis, four-axis, five-axis, or six-axis arm). In such embodiments, the second positioner 108 and / or the scan lens 112 may be carried by an end effector of the robot arm, as appropriate. In yet other embodiments, the workpiece 102 may be carried directly on the end effector of the multi-axis articulated robot arm (i.e., without the third positioner 110). In yet other embodiments, the third positioner 110 may be carried on the end effector of the multi-axis articulated robot arm.

[0052] D. Scan Lens In general, the scan lens 112 (e.g., provided as either a simple lens or a compound lens) is typically configured to focus a laser energy beam directed along a beam path to generate a beam waist that may be located at or near a desired process spot. The scan lens 112 may be provided as an f-theta lens, a telecentric lens, an axicon lens (in which case a series of beam waists are generated resulting in multiple process spots offset from one another along the beam axis), or the like, or any combination thereof. The scan lens 112 may be provided as a non-telecentric lens (as shown), an f-theta lens, a telecentric lens, an axicon lens (in which case a series of beam waists are generated resulting in multiple process spots offset from one another along the beam axis), or the like, or any combination thereof.

[0053] In one embodiment, the scan lens 112 is provided as a fixed focal length lens and is coupled to a scan lens positioner (e.g., a lens actuator, not shown) capable of moving the scan lens 112 (e.g., to change the position of the beam waist along the beam axis). For example, the lens actuator may be provided as a voice coil capable of linearly translating the scan lens 112 along the Z direction. In this case, the scan lens 112 may be formed from materials such as fused silica, optical glass, zinc selenide, zinc sulfide, germanium, gallium arsenide, magnesium fluoride, etc. In another embodiment, the scan lens 112 is provided as a variable focal length lens (e.g., a zoom lens, or a so-called "liquid lens" incorporating technology currently offered by COGNEX, VARIOPTIC, etc.) that can be actuated (e.g., via a lens actuator) to change the position of the beam waist along the beam axis. By changing the position of the beam waist along the beam axis, the spot size at the workpiece 102 can be changed.

[0054] In embodiments in which apparatus 100 includes a lens actuator, the lens actuator may be coupled to scan lens 112 (e.g., to allow scan lens 112 to move relative to second positioner 108 within the scan head). Alternatively, the lens actuator may be coupled to scan head 120 (e.g., to allow the scan head itself to move, where scan lens 112 and second positioner 108 move together). In other embodiments, scan lens 112 and second positioner 108 are integrated into different housings (e.g., such that the housing in which scan lens 112 is integrated is moveable relative to the housing in which second positioner 108 is integrated).

[0055] F. Controller Generally, the apparatus 100 includes one or more controllers, such as controller 122, for controlling or facilitating the control and operation of the apparatus 100. In one embodiment, the controller 122 is communicatively coupled (e.g., via one or more wired or wireless serial or parallel communication links, such as USB, RS-232, Ethernet, Firewire, Wi-Fi, RFID, NFC, Bluetooth, Li-Fi, SERCOS, MARCO, EtherCAT, or the like, or any combination thereof) to one or more components of the apparatus 100, such as the laser source 104, the first positioner 106, the second positioner 108, the third positioner 110, the lens actuator, the scan lens 112 (if provided as a variable focal length lens), the fixture, etc., such that these components operate in response to one or more control signals output by the controller 122.

[0056] For example, the controller 122 may control the operation of the first positioner 106, the second positioner 108, or the third positioner 110, or any combination thereof, to effect relative motion between the beam axis and the workpiece, and to effect relative motion between the process spot and the workpiece 102 along a path or trajectory (also referred to herein as a “process trajectory”) within the workpiece 102. It will be appreciated that any two of these positioners, or all three of these, may be controlled such that two positioners (e.g., the first positioner 106 and the second positioner 108, the first positioner 106 and the third positioner 110, the second positioner 108 and the third positioner 110) or all three positioners simultaneously effect relative motion between the process spot and the workpiece 102 (thereby effecting a “compound relative motion” between the beam axis and the workpiece). Of course, at any one time, it is also possible to control only one positioner (e.g., the first positioner 106, the second positioner 108 or the third positioner 110) to cause relative motion between the process spot and the workpiece 102 (thereby causing "non-compound relative motion" between the beam axis and the workpiece).

[0057] In one embodiment, the controller 122 may control the operation of the first positioner 106 to deflect the beam path 114 within the primary angular range 116 in a manner that causes compound or non-compound relative motion between the beam axis and the respective workpiece 102 (e.g., in conjunction with the second positioner 108, or in conjunction with the third positioner 110, or in conjunction with any combination thereof) to cause relative motion between the process spot and the workpiece 102 along a process trajectory within the workpiece 102. In other embodiments, the controller 122 may control the operation of the first positioner 106 to deflect the beam path 114 within the respective primary angular range 116 in a manner that compensates for tracking errors introduced by the second positioner 108.

[0058] Other examples of actions that can be controlled to be performed by one or more of the above-mentioned components include those disclosed in the above-mentioned U.S. Patent Nos. 5,751,585, 5,847,960, 6,606,999, 8,680,430, and 8,847,113, or those disclosed in U.S. Patent Nos. 4,912,487, 5,633,747, 5,638,267, 5,917,300, 6,3 No. 14,463, No. 6,430,465, No. 6,600,600, No. 6,606,998, No. 6,816,294, No. 6,947,454, No. 7,019,891, No. 7,027,199 , No. 7,133,182, No. 7,133,186, No. 7,133,187, No. 7,133,188, No. 7,244,906, No. 7,245,412, No. 7,259,354, No. 7,611, 745, 7,834,293, 8,026,158, 8,076,605, 8,288,679, 8,404,998, 8,497,450, 8,648,277, 8,896,909, 8,928,853, 9,259,802, or as disclosed in U.S. Patent Application Publication Nos. 2014 / 0026351, 2014 / 0196140, 2014 / 01962140, 2014 / 0196351 ... 014 / 0263201, 2014 / 0263212, 2014 / 0263223, 2014 / 0312013, or in German Federal Patent Publication No. DE102013201968B4, or in International Patent Publication No. WO2009 / 087392, or any combination thereof, each of which is incorporated herein by reference in its entirety.In another example, the controller 122 may control the operation of any positioners, including one or more AODs (e.g., in an embodiment, the first positioner 106, the second positioner 108, or a combination thereof) to vary the spot shape or spot size of the laser energy beam irradiated at the process spot (e.g., by chirping the RF signal applied to one or more ultrasonic transducer elements of one or more AODs, by applying a spectrally shaped RF signal to one or more ultrasonic transducer elements of one or more AODs, or the like, or any combination thereof), as disclosed in, for example, International Patent Publication No. WO2017 / 044646A1, which is incorporated herein by reference in its entirety. The applied RF signal may be chirped linearly or nonlinearly in any desired or suitable manner. For example, the applied RF signal may be chirped at a first rate and then chirped at a second rate to diffract the laser energy beam passing through the AO cell in two different ways. In this case, the first speed may be slower or faster than the second speed.

[0059] Typically, the controller 122 includes one or more processors operable to generate the control signals described above upon execution of instructions. The processor may be provided as a programmable processor (e.g., including one or more general purpose computer processors, microprocessors, digital signal processors, etc., or any combination thereof) operable to execute instructions. The instructions executable by the processor may be implemented as software, firmware, etc., or any suitable form of circuitry (including digital, analog, mixed analog / digital circuitry), including programmable logic devices (PLDs), field programmable gate arrays (FPGAs), field programmable object arrays (FPOAs), application specific integrated circuits (ASICs), etc., or any combination thereof. Execution of the instructions may be performed on a single processor, distributed across multiple processors, in parallel across multiple processors within a device or across a network of devices, or the like, or any combination thereof.

[0060] In one embodiment, the controller 122 includes tangible media such as computer memory accessible by the processor (e.g., via one or more wired or wireless communication links). As used herein, "computer memory" includes magnetic media (e.g., magnetic tape, hard disk drive, etc.), optical disks, volatile or non-volatile semiconductor memory (e.g., RAM, ROM, NAND flash memory, NOR flash memory, SONOS memory, etc.), and the like, which may be locally accessible or remotely accessible (e.g., over a network), or any combination thereof. In general, instructions may be stored as computer software (e.g., executable code, files, instructions, etc., library files, etc.). Such computer software may be written in, for example, C, C++, Visual Basic, Java, Python, Tel, Perl, Scheme, Ruby, assembly language, hardware description language (e.g., VHDL, VERILOG, etc.), etc., and may be readily produced by one of ordinary skill in the art from the description set forth herein. Computer software is typically stored in one or more data structures carried by the computer memory.

[0061] Although not shown, one or more drivers (e.g., RF drivers, servo drivers, line drivers, power supplies, etc.) may be communicatively coupled to inputs of one or more components such as the laser source 104, the first positioner 106, the second positioner 108, the third positioner 110, the lens actuator, the scan lens 112 (if provided as a variable focal length lens), etc., to control such components. Thus, one or more components such as the laser source 104, the first positioner 106, the second positioner 108, the third positioner 110, the lens actuator, the scan lens 112 (if provided as a variable focal length lens), etc. may also be considered to include any suitable driver as known in the art. Each driver typically includes an input to which a controller 122 is communicatively coupled, which is capable of generating one or more control signals (e.g., trigger signals, etc.) that may be sent to inputs of one or more drivers associated with one or more components of the device 100. In this manner, components such as the laser source 104, the first positioner 106, the second positioner 108, the third positioner 110, the lens actuator, and the scan lens 112 (if provided as a variable focal length lens) are responsive to control signals generated by the controller 122.

[0062] Although not shown, one or more additional controllers (e.g., component-specific controllers) may be communicatively coupled to inputs of drivers communicatively coupled to (and associated with) components such as the laser source 104, the first positioner 106, the second positioner 108, the third positioner 110, the lens actuator, and the scan lens 112 (if provided as a variable focal length lens), as desired. In this embodiment, each component-specific controller may be communicatively coupled to the controller 122 and capable of generating one or more control signals (e.g., trigger signals, etc.) in response to one or more control signals received from the controller 122. The one or more control signals may then be transmitted to inputs of the driver communicatively coupled thereto. In this embodiment, the component-specific controllers may be operable in a manner similar to that described with respect to the controller 122.

[0063] In other embodiments where one or more component-specific controllers are provided, a component-specific controller associated with a component (e.g., laser source 104) may be communicatively coupled to a component-specific controller associated with a component (e.g., first positioner 106, etc.) In this embodiment, one or more of the component-specific controllers may generate one or more control signals (e.g., trigger signals, etc.) in response to one or more control signals received from one or more other component-specific controllers.

[0064] III. Additional discussion on multi-axis AOD systems In many embodiments described herein, the first positioner 106 is provided as a multi-axis AOD system. Depending on the configuration of the AOD within the AOD system, the AOD may be characterized as a longitudinal mode AOD or a shear mode AOD and may be capable of diffracting a linearly or circularly polarized laser energy beam. Thus, depending on the wavelength of the laser energy beam and the material forming the AO cells of the AODs in the AOD system, the AODs within may be oriented such that the diffraction axis of the AO cells within the AOD is parallel or perpendicular (or at least substantially parallel or perpendicular) to the plane of polarization of the laser energy beam incident thereon. For example, the wavelength of the laser energy beam is in the ultraviolet or visible green region of the electromagnetic spectrum, the AO cells of the AOD are formed from a material such as quartz, and the AOD may be oriented such that the diffraction axis of the AO cells is perpendicular (or at least substantially perpendicular) to the plane of polarization of the incident laser energy beam. In another example, where the wavelength of the laser energy beam is in the so-called mid-wavelength infrared or long-wavelength infrared region of the electromagnetic spectrum (i.e., wavelengths ranging from 3 μm (or thereabouts) to 15 μm (or thereabouts)), and the AO cell of the AOD is formed from a material such as crystalline germanium, the AOD can be oriented so that the diffraction axis of the AO cell is parallel (or at least substantially parallel) to the plane of polarization of the incident laser energy beam.

[0065] 2, the multi-axis AOD system may be provided as a multi-cell multi-axis AOD system 200 including a first AOD 202 and a second AOD 204. Either of the first AOD 202 and the second AOD 204 may be provided by the methods described above. The first AOD 202 is positioned and operable to rotate an incident laser energy beam (e.g., propagating along beam path 114) by any angle (e.g., measured relative to the beam path 114 incident on the first AOD 202) about a first axis of rotation within a first angular range (also referred to herein as a "first AOD angular range 206") to transmit a primary beam propagating along a deflected beam path 114'. Similarly, the second AOD 204 is positioned and operable to rotate the incident laser energy beam transmitted through the first AOD 202 by any angle (e.g., measured relative to the beam path 114' incident on the second AOD 204) within a second angular range (also referred to herein as the "second AOD angular range 208") about a second axis of rotation to transmit the primary beam propagating along a deflected beam path 114". As can be appreciated, each of beam path 114' and beam path 114" represent specific examples of paths along which a laser energy beam can propagate. Accordingly, each of beam path 114' and beam path 114" can also be collectively referred to herein as "beam path 114".

[0066] Typically, the second AOD 204 is oriented with respect to the first AOD 202 such that the second axis of rotation is different from the first axis of rotation. For example, the second axis of rotation may be orthogonal to the first axis of rotation or oblique to the first axis of rotation. The diffraction axis of the second AOD 204 (also referred to as the "second diffraction axis") may be orthogonal to the diffraction axis of the first AOD 202 (also referred to as the "first diffraction axis") or oblique to the diffraction axis of the first AOD 202, if the diffraction axis of the AOD is orthogonal to the rotation axis of the AOD. However, in other embodiments, the second AOD 204 is oriented with respect to the first AOD 202 such that the second axis of rotation is parallel (or at least substantially parallel) to the first axis of rotation. In this case, one or more optical components can be positioned in the beam path 114' to rotate the polarization plane of the first AOD 202 (e.g., by 90 degrees or thereabouts) relative to the direction of the polarization plane of the second AOD 204 when projected onto the second AOD 204, and to rotate the polarization plane of the first AOD 202 (e.g., by 90 degrees or thereabouts) so that the second diffraction axis is parallel (or at least substantially parallel) to the first diffraction axis. See, for example, International Publication No. WO 2019 / 060590 A1 for examples of how the polarization plane may be rotated as described above. When the polarization plane of the first AOD 202 is rotated in the manner described above, the first diffraction axis projected onto the second AOD 204 is rotated (e.g., by 90 degrees or thereabouts) relative to the direction of the second diffraction axis.

[0067] In general, the AO cells in the first AOD 202 are formed from materials that may be the same or different from the AO cells in the second AOD 204. Additionally, the type of acoustic waves that the first AOD 202 uses to polarize an incident laser energy beam may be the same as or different from the type of acoustic waves that the second AOD 204 uses to polarize an incident laser energy beam.

[0068] It will be appreciated that at any given time the AOD system 200 may be operated such that only the first AOD 202 generates a primary beam, or only the second AOD 204 generates a primary beam, or both the first AOD 202 and the second AOD 204 generate primary beams. Thus, the deflection of the beam path 114 caused by the first positioner 106 may be considered to result solely from the deflection obtained from beam path 114', or solely from the deflection obtained from beam path 114", or from a superposition of the deflections obtained from beam paths 114' and 114". Similarly, the primary angular range 116 may be considered to be solely the first AOD angular range 206, or solely the second AOD angular range 208, or a superposition of the first AOD angular range 206 and the second AOD angular range 208. When the first positioner 106 is provided as an AOD system, such as AOD system 200, the first positioner 106 may include one or more other additional optical components, such as a beam trap, a beam expander, a beam shaper, an aperture, a filter, a collimator, a lens, a mirror, a phase retarder, a polarizer, or the like, or any combination thereof, as required.

[0069] IV. Discussion on Diffraction Efficiency in AOD Systems As used herein, the term "diffraction efficiency" refers to the fraction of energy in a laser energy beam incident on an AOD that is diffracted into a first order beam within the AO cell of the AOD. Thus, diffraction efficiency may be expressed as the ratio of the optical power of the first order beam generated by the AOD to the optical power of the incident laser energy beam incident on the AOD. In general, the amplitude of the applied RF drive signal may have a non-linear effect on the diffraction efficiency of the AOD, which may also vary as a function of the frequency of the RF drive signal applied to drive the AOD. In view of the above, in an embodiment in which the first positioner 106 is provided as the AOD system 200 described above, the first RF drive signal applied to drive the first AOD 202 may be characterized as having an amplitude (also referred to herein as the "first amplitude"), and the second RF drive signal applied to drive the second AOD 204 may be characterized as having an amplitude (also referred to herein as the "second amplitude").

[0070] Generally, the first amplitude may be selected or set based on one or more factors such as a first drive frequency of the first RF drive signal, a desired diffraction efficiency when the first AOD202 is driven by the first RF drive signal, a peak optical power of the laser energy beam deflected during the period when the first AOD202 is driven by the first RF drive signal, an average optical power of the laser energy beam deflected during the period when the first AOD202 is driven by the first RF drive signal, or any combination thereof. Similarly, the second amplitude may be selected or set based on one or more factors such as a second drive frequency of the second RF drive signal, a desired diffraction efficiency when the second AOD204 is driven by the second RF drive signal, a peak optical power of the laser energy beam deflected during the period when the second AOD204 is driven by the second RF drive signal, an average optical power of the laser energy beam deflected during the period when the second AOD204 is driven by the second RF drive signal, or any combination thereof.

[0071] V. Pulse Slicing Embodiments As discussed above, regardless of whether first positioner 106 is provided as a single-axis AOD system or a multi-axis AOD system (such as AOD system 200), first positioner 106 can be operated to perform pulse slicing, i.e., to split in time a common laser pulse (also referred to herein as a "mother laser pulse") into at least two laser pulses. As will be appreciated, a pulse slice can be considered a type of laser pulse.

[0072] One embodiment of pulse slicing is exemplarily shown in FIG. 3, where a mother laser pulse 300 is split in time into two pulse slices. Specifically, during a first slice period p1, the mother laser pulse 300 is split into a first pulse slice 300a, and during a second slice period p2, the mother laser pulse 300 is split into a second pulse slice 300b. As will be appreciated, the pulse duration of a pulse slice generally corresponds to the length of the slice period split in time from its mother laser pulse. Thus, for example, the first pulse slice 300a can be characterized as having a pulse duration equal to the first slice period p1, and the second pulse slice 300b can be characterized as having a pulse duration equal to the second slice period p2. Further, as will be appreciated, the pulse duration of a pulse slice may correspond to (e.g., be equal to or at least substantially equal to) the update rate of the first positioner 106 during pulse slicing, an integer multiple of the update rate of the first positioner 106 during pulse slicing, or a combination thereof.

[0073] Successive slice periods may occur consecutively (i.e., one slice period begins immediately after the preceding slice period), or may occur intermittently (i.e., one slice period begins after a delay immediately after the preceding slice period), or a combination thereof. It will be appreciated that when successive slice periods occur intermittently, the length of the delay may be characterized as an integer multiple of the positioning period of the first positioner 106 (which integer may be any integer, such as 1, 2, 3, 4, 5, 10, 20, 50, 100, etc., or any value therebetween). The embodiment shown in FIG. 3 is an example of successive slice periods p1 and p2 occurring intermittently. In view of the above, it will be appreciated that the pulse slices output by the AOD system 200 may constitute a laser energy beam having a pulse repetition rate that is equal to or a multiple of the update rate of the AOD system 200 when the system 200 is operated to perform pulse slicing.

[0074] The total time applied to the common mother laser pulse from the start of the first slice period to the end of the last slice period is less than or equal to the pulse duration of the mother laser pulse (based on the full width at half maximum (FWHM) of the optical power with respect to time). The mother laser pulse can generally be characterized as having a pulse duration longer than the positioning period of the first positioner 106. In an embodiment, the pulse duration of the mother laser pulse is longer than, equal to, or shorter than 1 μs, 2 μs, 5 μs, 10 μs, 15 μs, 20 μs, 25 μs, 30 μs, 40 μs, 50 μs, 100 μs, 300 μs, 500 μs, 900 μs, 1 ms, 2 ms, 5 ms, 10 ms, 20 ms, 50 ms, 100 ms, 300 ms, 500 ms, 900 ms, 1 s, etc., or any value therebetween.

[0075] In one embodiment, the length of each slice period (and thus the pulse duration of each pulse slice) is an integer multiple of the positioning period of the first positioner 106 (eg, the integer is 1, 2, 3, 5, 10, etc., or any value therebetween). In some embodiments, the length of each slice period is greater than, equal to, or less than 200 μs, 125 μs, 100 μs, 50 μs, 33 μs, 25 μs, 20 μs, 13.3 μs, 12.5 μs, 10 μs, 4 μs, 2 μs, 1.3 μs, 1 μs, 0.2 μs, 0.1 μs, 0.05 μs, 0.025 μs, 0.02 μs, 0.013 μs, 0.01 μs, 0.008 μs, 0.0067 μs, 0.0057 μs, 0.0044 μs, 0.004 μs, etc., or any value therebetween. In general, the length of one or more slice periods of a mother laser pulse may be the same as or different from the length of one or more other slice periods of the same mother laser pulse. For example, although FIG. 3 illustrates the first slice period p1 as being equal to the second slice period p2, the length of the first slice period p1 may be longer or shorter than the duration of the second slice period p2.

[0076] Although FIG. 3 illustrates the mother laser pulse 300 being split in time into only two pulse slices (i.e., a first pulse slice 300a and a second pulse slice 300b), it will be understood that the mother laser pulse 300 may be split in time into more than two pulse slices (e.g., three pulse slices, five pulse slices, eight pulse slices, ten pulse slices, twenty-five pulse slices, thirty pulse slices, fifty pulse slices, or the like, or any value therebetween). For example, referring to FIG. 4, the laser pulse 300 may be split in time into four pulse slices 400a, 400b, 400c, and 400d. In one embodiment, the operation of the first positioner 106 is controlled such that the pulse slices in at least one pair of the sequentially split pulse slices are deflected within different first-order angular ranges 116. For example, pulse slice 400a can be deflected within the primary angular range 116 (e.g., by a first angle), then pulse slice 400b can be deflected within the primary angular range 116 (e.g., by a second angle), then pulse slice 400c can be deflected within the primary angular range 116 (e.g., by a third angle), then pulse slice 400d can be deflected within the primary angular range 116 (e.g., by a fourth angle). In other embodiments, the operation of the first positioner 106 is controlled such that pulse slices in at least one pair of sequentially divided pulse slices are deflected by the same angle within the primary angular range 116.

[0077] Outside the slice period, the first positioner 106 can be operated by any method known in the art to attenuate the incident laser energy beam so that the laser energy beam propagating along the beam path 114 has insufficient energy to process the workpiece 102 when ultimately deflected by the first positioner 106. Additionally or alternatively, outside of the slice interval, the first positioner 106 can be operated to deflect the beam path 114 towards a beam trap, a beam dump system, or the like, or any combination thereof. Additionally or alternatively, outside of the slice interval, the first positioner 106 can be deactivated to allow the incident laser energy beam to be transmitted through the AOD of the first positioner 106 and directed towards a beam trap, a beam dump system, or the like, or any combination thereof.

[0078] Although pulse slicing has been described above with respect to a single mother laser pulse (i.e., laser pulse 300), it will be appreciated that the first positioner 106 may be operated to perform pulse slicing with respect to a series of successively propagating mother laser pulses, in which successive mother laser pulses may be separated in time in any desired manner, and two successive mother laser pulses may be separated in time in the same manner or in different manners.

[0079] A. Additional discussion on diffraction efficiency During a slice period, the first positioner 106 may be operated to attenuate the incident laser energy beam such that the optical power of the pulse slice is constant over time, or varies over time, or any combination thereof. For example, the AODs (e.g., the first AOD 202, the second AOD 204, or a combination thereof) may be driven to attenuate the incident laser energy beam by maintaining and / or varying the amplitude of the RF drive signal provided to the AOD during the slice period (e.g., while holding the frequency of the provided RF drive signal constant). Thus, for example, the optical power of the first pulse slice 300a may be constant or vary during the first slice period p1. Similarly, the optical power of the second pulse slice 300b may be constant or vary during the second slice period p2.

[0080] The first positioner 106 can be operated to attenuate the incident laser energy beam (e.g., by maintaining and / or varying the amplitude of the RF drive signal provided to the AOD over successive slice periods) such that the two average and / or peak optical powers are constant or vary over successive slice periods in which a common mother laser pulse is divided in time into multiple pulse slices. Thus, for example, the average or peak optical power of the first pulse slice 300a during the first slice period p1 can be greater than, equal to, or less than the average or peak optical power of the second pulse slice 300b during the second slice period p2. In other examples, the average or peak optical power of pulse slice 400a can be greater than, equal to, or less than the average or peak optical power of any of pulse slices 400b, 400c, 400d. The average or peak optical power of pulse slice 400b may be greater than, equal to, or less than the average or peak optical power of either of pulse slices 400c and 400d. The average or peak optical power of pulse slice 400c may be greater than, equal to, or less than the average or peak optical power of pulse slice 400d.

[0081] Although the above discussion of the operation of the first positioner 106 is in terms of setting or varying the optical power of a pulse slice (i.e., when the first positioner 106 is operated to perform a partial pulse deflection), it will be understood that the first positioner 106 can similarly be operated to set or vary the optical power of a deflected pulse of laser energy when the first positioner 106 performs a full pulse deflection.

[0082] VI. BEAM SPLIT EMBODIMENTS 1 illustrates an embodiment in which the laser processing apparatus 100 includes a single second positioner 108, it will be understood that many of the embodiments disclosed herein are applicable to laser processing apparatuses including multiple (i.e., two or more) second positioners 108. For example, referring to FIG. 31, a laser processing apparatus 3100 may be provided in a manner similar to the laser processing apparatus 100 described above, but may include multiple second positioners (e.g., second positioners 108a and 108b, each collectively referred to as "second positioner 108") and multiple scan lenses (e.g., scan lenses 112a and 112b, each collectively referred to as "scan lenses 112"). As with the laser processing apparatus 100, the scan lenses 112 and corresponding second positioners 108 may be integrated into a common housing or "scan head" if desired. As such, scan lens 112a and corresponding second positioner 108 (i.e., second positioner 108a) may be integrated into a common scan head 120a. Similarly, scan lens 112b and corresponding second positioner 108 (i.e., second positioner 108b) may be integrated into a common scan head 120b. As used herein, each of scan head 120a and scan head 120b may also be collectively referred to herein as "scan head 120."

[0083] If the first positioner 106 is integrated into the laser processing apparatus 3100, the first positioner 106 may be capable of diffracting, reflecting, refracting, or deflecting the laser energy beam to redirect the beam path 114 to either of the second positioners 108. When deflecting the beam path 114 to the second positioner 108a, the beam path 114 may be deflected at any angle (e.g., measured relative to the beam path 114 entering the first positioner 106) within a first angular range (also referred to herein as a "first primary angular range 116a"). Similarly, when deflecting the beam path 114 to the second positioner 108b, the beam path 114 may be deflected at any angle (e.g., measured relative to the beam path 114 entering the first positioner 106) within a second angular range (also referred to herein as a "second primary angular range 116b"). As used herein, each of the first primary angular range 116a and the second primary angular range 116b may also be collectively referred to herein as a "primary angular range 116." Generally, the first primary angular range 116a does not overlap or border the second primary angular range 116b. The first primary angular range 116a may be greater than, less than, or equal to the second primary angular range 116b. As used herein, deflecting the beam path 114 within one or more of the primary angular ranges 116 is referred to herein as "beam divergence."

[0084] In one embodiment, the operation of the first positioner 106 may be controlled to deflect the beam path 114 to the second positioner 108a (e.g., during a first branching period) and to deflect the beam path 114 to the second positioner 108b (e.g., during a second branching period after the first branching period), or vice versa, or a combination thereof. In another example, the operation of the first positioner 106 may be controlled to simultaneously deflect the beam path 114 to the second positioner 108a and the second positioner 108b. In the embodiments described herein, the length of the first branching period may be longer, shorter, or equal to the length of the second branching period. The length of each of the first branching period and the second branching period may be longer, shorter, or equal to the positioning period of the first positioner 106. In one embodiment, the length of each of the first and second branch periods can be characterized as an integer multiple of the positioning period of the first positioner 106 (which can be an integer of 1, 2, 3, 4, 5, 10, 20, 50, 100, etc., or any integer between any of these values). See the section below for further discussion regarding the "positioning period" of the first positioner 106. In one embodiment, the length of each branch period may be longer than, shorter than, or equal to 200 μs, 125 μs, 100 μs, 50 μs, 33 μs, 25 μs, 20 μs, 13.3 μs, 12.5 μs, 10 μs, 4 μs, 2 μs, 1.3 μs, 1 μs, 0.2 μs, 0.1 μs, 0.05 μs, 0.025 μs, 0.02 μs, 0.013 μs, 0.01 μs, 0.008 μs, 0.0067 μs, 0.0057 μs, 0.0044 μs, 0.004 μs, etc., or a value between any of these values.

[0085] In cases where the laser energy beam output by the laser source 104 is represented as a series of laser pulses, each branch period may have a duration equal to or greater than the pulse duration of a laser pulse in the laser energy beam. However, in other embodiments, one or more branch periods may have a duration less than the pulse duration of a laser pulse in the laser energy beam. In such embodiments (or in embodiments where the laser energy beam output by the laser source 104 is represented as a continuous or quasi-continuous laser beam), the beam branching may result in pulse slicing, thereby producing one or more pulse slices.

[0086] VII. Feature Formation In general, whether provided in a laser processing apparatus described with respect to FIG. 1 or FIG. 31 or other laser processing apparatus, the first positioner 106 can be operated and used to rapidly scan or position a process spot within a first scan range (e.g., as described above) to form features (e.g., openings, vias, trenches, slots, scribe lines, recesses, etc.) in the workpiece 102. In some embodiments, the workpiece 102 can be provided as a PCB panel, a PCB, an FPC, an IC, an ICP, a semiconductor device, etc. Thus, the workpiece 102 can include one or more component structures such as a conductor structure (e.g., a film, foil, etc. that may be formed from copper, a copper alloy, a wiring or conductive line structure including one or more metals such as copper, titanium, titanium nitride, tantalum, etc., or any combination thereof), a dielectric structure (e.g., a build-up film, a fiberglass reinforced epoxy laminate, an interlayer dielectric material, a low-k dielectric material, a solder resist, a polymeric material, etc., or any combination thereof), etc., or any combination thereof. The conductive or dielectric structures of the workpiece 102 may have a thickness in the range of 5 μm (or thereabouts) to 500 μm (or thereabouts). Thus, the thickness of the conductive or dielectric structures may be greater than, less than, or equal to 0.5 μm, 0.1 μm, 1 μm, 3 μm, 5 μm, 10 μm, 15 μm, 18 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 50 μm, 70 μm, 80 μm, 100 μm, 110 μm, 120 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 550 μm, 600 μm, etc., or a value between any of these values.

[0087] In one embodiment, referring to FIG. 5, the workpiece 102 includes a dielectric structure 500 on a first side thereof contacted or attached to a first conductive structure 502. The dielectric structure 500 may be provided as a material such as FR4, polyimide, liquid crystal polymer, ABF, etc., and may have a thickness (t1) ranging from 15 μm (or thereabouts) to 120 μm (or thereabouts). The first conductive structure 502 may be provided as a copper or copper alloy foil that may be treated, for example, by a chemical reaction or by a laser darkening process, to increase the absorption of laser energy, or may have an exposed surface that is not darkened. A second conductive structure 504 (e.g., a pad, trace, foil, etc., formed of copper or a copper alloy, etc.) may be contacted or attached to a second side of the dielectric structure 500 opposite the first side. The first conductive structure 502 may have a thickness (t2) equal to (or approximately equal to) 5 μm, 7 μm, 9 μm, 12 μm, 18 μm, 35 μm, 70 μm, 105 μm, etc., or a value between any of these values. If a second conductive structure is present, the second conductive structure may have a thickness (t3) that is less than, greater than, or equal to the thickness (t1) of the first conductive structure 502. Optionally, the workpiece 102 may include one or more additional structures, such as an additional dielectric structure 508 partially shown in FIG. 5, that the second conductive structure 504 contacts or is attached to the second conductive structure 504 (e.g., such that the second conductive structure 504 resides between the dielectric structure 500 and the dielectric structure 508).

[0088] In general, features (e.g., openings, vias, trenches, slots, scribe lines, recesses, etc.) can be characterized as being formed by removing material from one or more constituent structures of the workpiece 102 by ablation. Unless expressly stated, the term "ablation" may refer to "direct ablation," "indirect ablation," or any combination thereof. Direct ablation of a material in the workpiece 102 occurs when the primary cause of ablation is the breakdown of the material due to the material's absorption (e.g., linear absorption, nonlinear absorption, or any combination thereof) of the energy in the irradiated laser energy beam. Indirect ablation (also known as "lift-off") of a target material (e.g., a first conductor) in the workpiece 102 occurs when the primary cause of ablation is melting and vaporization due to heat transferred within and from an adjacent material that absorbs the energy in the laser energy beam that is ultimately irradiated on the workpiece 102. Removal of the target material (e.g., first electrical conductor 502) occurs when pressure within a pocket of evaporated material between the target material and an adjacent material (e.g., resulting from evaporation of the adjacent material) is sufficient to eject the target material from the workpiece 102. Considerations regarding material removal by indirect ablation are known in the art and are described in more detail in International Publication No. WO 2017 / 044646 A1.

[0089] A. Feature formation using scan patterns To form features such as vias (e.g., blind via 600 as illustratively shown in FIG. 6 and through via 700 as illustratively shown in FIG. 7 ) in the workpiece 102 (e.g., configured as described above), the first positioner 106 may be provided as a multi-axis AOD system (e.g., AOD system 200) and operated to scan a process spot (i.e., a spot on the workpiece 102 irradiated with a laser energy beam directed at the workpiece 102, as indicated by arrow 506 in FIG. 5 ) along a process trajectory that defines a scan pattern. When the laser energy beam irradiated at the workpiece 102 is represented as a plurality of pulses, the scan pattern may be characterized as a pattern of spot positions distributed within an area of ​​the workpiece 102 where the feature (e.g., a via) is to be formed. During formation of the feature, the first positioner 106 may be operated to provide full pulse deflection (e.g., as described above), partial pulse deflection, or a combination of full pulse deflection and partial pulse deflection.

[0090] In general, the maximum dimension of the scan pattern (measured in the XY plane) is smaller than or equal to the maximum dimension of the first scan area (measured in the XY plane). Furthermore, the spot size of the process spot scanned along the scan pattern used to form the via is smaller than the maximum dimension (measured in the XY plane) of the via itself (formed in the first conductor structure 502). Thus, the maximum dimension of the via can be equal to (or approximately equal to) 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 105 μm, 110 μm, etc., or a value between any of these values. The maximum dimension (measured in the XY plane) of a via formed in the dielectric structure (e.g., at the bottom of the via or at or near the interface between the dielectric structure and the second conductor structure) may be greater than, less than, or equal to the maximum dimension of a via formed in the first conductor structure 502.

[0091] The scan pattern characteristics may include the number of spot locations in the scan pattern, the arrangement of the spot locations in the scan pattern, the order or sequence in which the spot locations are designated in the scan pattern, the distance between consecutively designated spot locations, etc. Typically, the spot locations are designated when a single laser pulse or a single set of consecutively applied laser pulses is applied to the workpiece 102 at the spot locations. According to embodiments described herein, one or more of these scan pattern characteristics may be selected or set taking into account one or more or all of the above characteristics (e.g., wavelength, average power, pulse duration, pulse repetition rate, pulse energy, peak power, temporal optical power profile, spot size, etc.) of the laser energy beam applied to the workpiece 102 such that the laser energy can be uniformly (or at least somewhat uniformly) distributed over the area of ​​the workpiece 102 where the via is to be formed before the first electrical conductor structure 502 is ultimately ablated (by indirect ablation or a combination of direct and indirect ablation). In this way, the area of ​​the first conductive structure 502 where the via is to be formed can be uniformly (or at least somewhat uniformly) heated to a temperature at or near the processing threshold temperature of the first conductive structure 502 before all spot locations in the scan pattern are designated. Thus, according to the embodiments described herein, the process of forming a via in the workpiece 102 can be characterized as including a process of forming an opening in the first conductive structure 502. Thus, the opening is formed in the first conductive structure 502 by first designating a plurality of spot locations in the scan pattern to uniformly (or at least somewhat uniformly) heat the area of ​​the first conductive structure 502 where the opening is to be formed (to a temperature at or near the processing threshold temperature of the first conductive structure 502), and then designating one or more other spot locations in the scan pattern to vaporize a portion of the dielectric structure 500 below the heated area of ​​the first conductive structure 502 to erupt the heated area of ​​the first conductive structure 502 from the workpiece 102 (i.e., by indirect ablation).

[0092] In view of the above, it will be appreciated that one or more of the scan pattern characteristics described above, in addition to the laser energy beam characteristics (e.g., average power, pulse duration, pulse repetition rate, pulse energy, peak power, spot size, etc., or any combination thereof) can be selected or set to melt all (at least substantially all) of the portions of the first conductive structure 502 located within the region of the workpiece 102 where the via is to be formed (including the region of the first conductive structure 502 located in the center of the region of the workpiece 102 where the via is to be formed (also referred to herein as the "central region of the first conductive structure 502"). However, one or more of the scan pattern characteristics, the laser energy beam characteristics, or a combination thereof can be modified to melt the central region of the first conductive structure 502, but not melt the portions of the first conductive structure 502 surrounding the central region, before the first conductive structure 502 is ablated (e.g., by indirect ablation). In this case, the unmelted central region of first conductor 502 can still be removed by indirect ablation (e.g., during evaporation of the dielectric structure below the unmelted central region of first conductor 502).

[0093] One or more of the scan pattern characteristics may also be selected or set considering the rate at which successively designated spot positions in the scan pattern are designated. The rate at which different spot positions in the scan pattern are designated may be equal (or at least substantially equal) to an update rate of the first positioner 106 during the formation of the vias, an integer multiple of the update rate of the first positioner 106 during the formation of the vias, or a combination thereof. Thus, the rate at which different spot positions in the scan pattern are designated may correspond to an update rate of the first positioner 106 during the formation of the vias. Thus, the total time required to scan the process spots along the scan pattern (also referred to herein as "exposure time") may correspond to the product of the number of spot positions in the scan pattern multiplied by the first positioning period of the first positioner 106 (when operating the first positioner 106 to scan the process spots along the scan pattern).

[0094] As discussed above, during the process of forming a via, laser energy is distributed uniformly (or at least somewhat uniformly) across the area of ​​the workpiece 102 where the via is to be formed before the first conductive structure 502 is ablated (e.g., by direct ablation, indirect ablation, or a combination thereof). Thus, at least two spot positions (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, etc.) of the scan pattern are specified before the first conductive structure 502 is ablated. For example, simulations performed by the inventors indicate that when a laser energy beam, represented as a series of laser pulses (i.e., having a wavelength such as 9.4 μm or 10.6 μm, a spot size of 70 μm, a pulse duration of 1 μs, and a peak power of up to about 1.3 kW) is irradiated on a workpiece 102 provided as a PCB having a dielectric structure formed from FR4 having a thickness of 50 μm (such that the laser energy beam is incident on the first conductive structure 502), a first conductive structure 502 formed from a copper foil having a thickness of 12 μm that has been treated to increase absorption of the laser energy, and a second conductive structure formed from a copper foil having a thickness of 35 μm, ablation of the first conductive structure 502 begins within a period of 6 μs to 8 μs (or thereabouts) after the process spot is first scanned. Thus, according to the simulations, approximately 6 to 8 spot locations can be designated by the laser energy beam before the first conductive structure 502 is ablated.

[0095] i. Example Scan Pattern Embodiments The following describes the scan patterns shown in Figures 8 to 22 and 24(a) which have been performed by the inventors to form circular (or at least generally circular) blind vias using a laser energy beam having a wavelength in the range of 9 μm (or thereabouts) to 11 μm (or thereabouts) (e.g., wavelengths of 9.4 μm (or thereabouts), 10.6 μm (or thereabouts), etc.) in the range of 9 μm (or thereabouts) to 11 μm (or thereabouts) in the workpiece 102 (provided, for example, as described above), a peak power in the range of 250 W (or thereabouts) to 2 kW (or thereabouts), and a spot size in the range of 60 μm (or thereabouts) to 90 μm (or thereabouts) to irradiate the workpiece 102. However, it will be appreciated that the spot size may be smaller than 60 μm, for example, in the range of 30 μm (or thereabouts) to 60 μm (or thereabouts). Thus, a process spot scanned along an exemplary scan pattern as described below may have a spot size of, for example, 40 μm (or thereabouts), 50 μm (or thereabouts), 70 μm (or thereabouts), or 85 μm (or thereabouts), or any value between these values. Typically, a pulse in the laser energy beam irradiated to the workpiece 102 has a pulse duration of 1 μs (or thereabouts). However, it will be understood that the scan patterns described below may be used to form features other than blind vias (e.g., through via trenches, slots, or other recesses or openings), and that the scan patterns may be modified to form features other than vias.

[0096] It will also be appreciated that the laser energy beam irradiated to the workpiece 102 may have a wavelength of 9 μm or less (e.g., in the ultraviolet or green region of the electromagnetic spectrum), provided that other characteristics of the laser energy beam irradiated to the workpiece 102 (e.g., pulse duration, pulse repetition rate, peak power, temporal optical power profile, fluence, etc.) are sufficient to process the workpiece 102. For example, the laser source 104 may be provided as a laser, such as the ULR / ULM-355-200 series lasers manufactured by IPG PHOTONICS. These lasers are high power QCW fiber lasers capable of generating a laser energy beam with a wavelength of 355 nm and an average power of 200 W. The beam is comprised of laser pulses having a pulse duration of about 1.4 ns and output at a pulse repetition rate of 80 MHz. In another example, the laser source 104 may be provided as a laser, such as the GPLN-532 series of lasers manufactured by IPG PHOTONICS (e.g., GPLN-532-200, GPLN-532-500, etc.). The laser may be operated in pulsed or QCW mode and may generate a laser energy beam at a wavelength of 532 nm and an average power of 200 W or more. The beam may be comprised of laser pulses having a pulse duration of about 1.2 ns and output at a pulse repetition rate of about 50 MHz or more.

[0097] Finally, regardless of the wavelength of the laser energy beam irradiated to the workpiece 102, it will be understood that the laser energy beam irradiated to the workpiece 102 may have any suitable or desired characteristics (e.g., spot size, pulse duration, peak power, pulse energy, average power, pulse repetition rate, etc.) based on one or more factors, such as the material composition of the workpiece 102 being processed, acceptable quality and throughput criteria, etc.

[0098] In Figures 8 through 22 and 24(a), the spot locations of the scan patterns are distributed in a circular arrangement (e.g., arranged on or along a common perimeter of an imaginary circle). In these figures, the center of each spot location is indicated by a dot or circle. The horizontal and vertical axes shown are for reference only, and the numbers on each axis indicate distance or position (measured in μm). Thus, the scan patterns shown in Figures 8 through 22 and 24(a) can be characterized as having radii in the range of 10 μm (or thereabouts) to 60 μm (or thereabouts).

[0099] In one embodiment, the scan pattern used to form the vias may be an adjacent furthest type scan pattern, in which a second or subsequent spot location assigned is as far away as possible from any other previously assigned spot location. Examples of adjacent furthest type scan patterns are shown in Figures 8 and 9.

[0100] 8, the adjacent-furthest type scan pattern is comprised of eight spot positions (each of which has a center represented by a dot, such as point 800), with each spot position being designated only once. As exemplarily illustrated, the eight spot positions are disposed in a circular arrangement (e.g., disposed on or along a common periphery of an imaginary circle). The lines connecting the spot positions and the numbers "1", "2", ... "8" adjacent the spot positions indicate the order in which the spot positions in the scan pattern 800 are designated (e.g., by at least one deflected laser energy beam by the first positioner 106). Thus, spot position 1 is the first spot position designated in the scan pattern 800, spot position 2 is the second spot position designated in the scan pattern 800, and so on, with spot position 8 being the last spot position designated in the scan pattern 800.

[0101] 9, the adjacent-farthest type scan pattern consists of 16 spot locations in a circular arrangement (e.g., arranged on or along a common perimeter of an imaginary circle). In the scan pattern shown in FIG. 9, each spot location overlaps another spot location. Thus, the point location identifiers "1,12", "2,11", "3,9", ... "5,16" indicate spot locations, and the lines connecting the spot locations indicate the order in which the spot locations are designated (e.g., by at least a deflected laser energy beam by the first positioner 106) in the scan pattern. Thus, in the scan pattern shown in FIG. 9, the point designated by "1,12" represents the location of the first spot location designated in the scan pattern 800 and the location of the twelfth spot location designated in the scan pattern 800, the point designated by "2,11" represents the location of the second spot location designated in the scan pattern and the location of the eleventh spot location designated in the scan pattern, and so on.

[0102] It will be appreciated that adjacent-furthest type scan patterns can be modified (e.g., so that a second or subsequent spot location specified is located as far away as possible from other previously specified spot locations) and still be suitable for use in forming vias. Examples of modified adjacent-furthest type scan patterns are shown in Figs. 10-22. The scan patterns shown in Figs. 10-22 (in addition to the scan patterns shown in Figs. 8 and 9) can generally be characterized as one of two types. In the first type of scan pattern (also referred to herein as "Type 1 scan patterns"), the midpoint between pairs of consecutively specified spot locations is located at the same location (e.g., the center of an imaginary circle). In the second type of scan pattern (also referred to herein as "Type 2 scan patterns"), the midpoint between pairs of consecutively specified spot locations is not located at the same location. Figs. 8-16, 20-22, and 24(a) show examples of Type 1 scan patterns, and Figs. 17-19 show Type 2 scan patterns.

[0103] A type 2 scan pattern can be characterized as a scan pattern in which adjacent spot locations are designated successively (e.g., as shown in Figures 17 and 19) or as a scan pattern in which adjacent spot locations are not designated successively (e.g., as shown in Figure 18). Scan patterns such as those shown in Figures 17 and 19 are referred to as "continuously designated type 2 scan patterns," and scan patterns such as those shown in Figure 18 are referred to as "non-continuously designated type 2 scan patterns."

[0104] In Figs. 17 and 19, spot positions 1 and 2 are examples of spot positions that are adjacent to one another and are designated consecutively. In Fig. 18, spot positions 1 and 7 are examples of spot positions that are adjacent to one another but are not designated consecutively. Rather, in Fig. 18, spot positions 1 and 2 are not adjacent to one another but are designated consecutively. In the example scan pattern shown in Fig. 18, spot position 7 is located between consecutively designated spot positions 1 and 2 (e.g., along the circumference of a virtual circle). Also, as shown in Fig. 18, spot positions 12 and 1 are located between consecutively designated spot positions 6 and 7 (e.g., along the circumference of a virtual circle). It will be appreciated that the scan patterns shown in Figs. 17-19 can be modified such that any number of spot positions can be located between any two consecutively designated spot positions within the same scan pattern (e.g., along the circumference of a virtual circle).

[0105] Although the example scan patterns shown in Figures 8-22 and 24(a) are shown as having a predetermined number of spot locations (e.g., 4, 8, 12, 16, 18, or 20 spot locations) disposed on or along a common perimeter of an imaginary circle, it will be understood that any scan pattern (whether shown or not) can have a different number of spot locations (e.g., 2, 3, 5, 6, 10, 15, 22, 25, 28, 30, 32, 40, 50, 60, 70, 75, 80, 100, etc., or any value between any of these values) disposed on or along a common perimeter of an imaginary circle, and the spot locations may be designated in any suitable or desired order or sequence. For example, while the example scan patterns shown in Figures 8, 10-13, and 15-20 are shown as having multiple spot locations that are sequentially designated only once, it will be understood that any spot location in these scan patterns may be sequentially designated multiple times (e.g., two, three, four, five, etc.), and it will be understood that spot locations within a common scan pattern may be located on or along other lines, edges, line segments, etc. that describe any desired or suitable shape (e.g., a triangle, square, rectangle, hexagon, ellipse, star, etc., or any combination thereof).

[0106] When scanning the process spot along the second type scan pattern such that non-adjacent spot locations are consecutively designated, any number of spot locations may be located between pairs of consecutively designated spot locations (e.g., along the circumference of an imaginary circle). The number of spot locations that may be located between such pairs of consecutively designated spot locations may range from 3 spot locations to 10 spot locations (e.g., range from 4 spot locations to 6 spot locations).

[0107] ii. Additional discussion on feature shape distortion It has been discovered that vias produced by operating the first positioner 106 (e.g., a multi-axis AOD system such as AOD system 200) to scan process spots along a type 2 scan pattern as described above may have an elliptical opening (at the surface of the workpiece 102), e.g., as shown in FIG. 27, even though the spot positions of the type 2 scan pattern are located on or along a common perimeter of an imaginary circle, e.g., as shown in FIG. 28. To compensate for this distortion in the shape of the via opening, the placement of the spot positions in the type 2 scan pattern can be modified (e.g., such that the spot positions are located on or along a common perimeter of an imaginary ellipse, as shown in FIG. 29). The modified type 2 scan pattern shown in FIG. 29 can be generally characterized as being elliptical in shape. The major axis of this elliptical shape is orthogonal to the major axis of the via opening shape shown in FIG. 27. Any type 2 scan pattern (including the type 2 scan pattern described above) can be modified such that the spot positions are located on or along a perimeter of a common ellipse, rather than located on or along the circumference of a common circle. Scanning the process spot along such a modified scan pattern will result in the final via opening having a more circular shape compared to the elliptical shape shown in FIG.

[0108] iii. Additional discussion on scan patterns, via circularity, and pulse slicing It should be noted that in Figures 8-22 and 24(a), the horizontal and vertical axes do not necessarily represent the direction of the diffraction axis of an AOD in a multi-axis AOD system (e.g., AOD system 200) that operates to scan a process spot along a scan pattern to form a via. In general, a process spot can be scanned along any scan pattern as described herein while operating AOD system 200 to perform full pulse deflection, partial pulse deflection (as described above) (i.e., pulse slicing), or a combination thereof. It has been found that when operating a multi-axis AOD system (e.g., AOD system 200) to perform partial pulse deflection, the circularity of the via opening ultimately formed can depend on one or more factors such as the direction of the scan pattern (i.e., the direction of the "jumps" between successively specified spot positions in the scan pattern relative to the direction of the diffraction axis of the AOD in the multi-axis AOD system), the distance between successively specified spot positions in the scan pattern, and the update rate of the multi-axis AOD system while the process spot is being scanned. Without wishing to be bound by any particular theory, the inventors believe that acoustic transients in the AO cell, which occur when the RF drive frequency applied to the AOD is changed during the passage of a laser pulse through the AO cell of the AOD during pulse slicing, diffract the incident laser energy beam in an undesirable manner. The diffraction phenomenon caused by the acoustic transients can sometimes produce an unacceptable degree of distortion of the process spot on the workpiece 102. It has been observed that the process spot distortion is most severe when the difference in the RF drive frequency applied to a particular AOD is large between two successive first positioning periods of the AOD. It has also been observed that the process spot distortion can be mitigated to some extent by operating multiple AODs of a multi-axis AOD system to sequentially address different spot locations in a scan pattern.

[0109] For example, in the scan pattern shown in Figure 14, the direction of the "jumps" between spot positions 1 and 2 (and between spot positions 7 and 8, and between spot positions 9 and 10) is parallel to one diffraction axis of an AOD in the multi-axis AOD system (e.g., the first diffraction axis of the first AOD 202 of AOD system 200), and the direction of the "jumps" between spot positions 3 and 4 (and between spot positions 5 and 6, and between spot positions 11 and 12) is parallel to the other diffraction axis of an AOD in the multi-axis AOD system (e.g., the second diffraction axis of the second AOD 204 of AOD system 200). Thus, the distance between successively designated spots aligned in the diagonally shown directions (each of which is parallel to the diffraction axis of an AOD in a multi-axis AOD system such as AOD system 200) is greater than the distance between successively designated spots aligned in the horizontal or vertical directions shown in the figure. Thus, when the process spot is scanned along the scan pattern shown in Figure 14, the shape of the process spot on the workpiece 102 may be distorted, resulting in a relatively out-of-round via opening (e.g., as shown in Figure 23). However, if the direction of the scan pattern shown in Figure 14 is rotated relative to the diffraction axis of the AODs in a multi-axis AOD system (e.g., by 45 degrees as shown in Figure 24(a)) so that the directions of the relatively large "jumps" (i.e., jumps between spot positions 1 and 2, between spot positions 3 and 4, between spot positions 5 and 6, between spot positions 7 and 8, between spot positions 9 and 10, and between spot positions 11 and 12) are not parallel to the diffraction axis of any of the AODs, the circularity of the resulting via opening can be improved, as shown in Figure 24(b). As shown in FIG. 14, only a single AOD is operated to scan the process spot between spot positions 1 and 2 (and between spot positions 7 and 8, and between spot positions 9 and 10), or between spot positions 3 and 4 (and between spot positions 5 and 6, and between spot positions 11 and 12).However, as shown in FIG. 24(a), multiple AODs need to be operated to scan the process spot between spot positions 1 and 2, between spot positions 3 and 4, between spot positions 5 and 6, between spot positions 7 and 8, between spot positions 9 and 10, and between spot positions 11 and 12. Similarly, the directions of the "jumps" between successively designated spot positions in the scan pattern shown in FIG. 16 are not parallel to the diffraction axis of any of the AODs in the multi-axis AOD system. As a result, when scanning the process spot along the scan pattern shown in FIG. 16, the ultimately produced via has a relatively high circularity opening (e.g., as shown in FIG. 25).

[0110] It should be noted that within an AOD, each applied RF drive frequency corresponds to an effective phase tilt imparted to the incident laser energy beam. In particular, the phase tilt (in μradians) can be calculated as follows:

number

[0111] For example, the direction of the "jump" between spot positions 1 and 2 in the scan pattern shown in Figure 8 is parallel to one diffraction axis of the AOD (e.g., the first diffraction axis of the first AOD 202 of the AOD system 200), and the direction of the "jump" between spot positions 3 and 4 is parallel to the other diffraction axis of the AOD (e.g., the second diffraction axis of the second AOD 204 of the AOD system 200). Thus, the longest jump achieved by a single AOD is equivalent to about 300μ radians of tilt, which corresponds to a phase tilt of about 4.5μm across the diameter of the laser energy beam passing through the AOD (which may be about 15mm, or about 50% of its 9.4μm wavelength). Thus, the jump from spot position 1 to spot position 2 and the jump from spot position 3 to spot position 4 are relatively large jumps.

[0112] Operating the AOD system 200 with partial pulse deflections to scan a process spot along the scan pattern shown in FIG. 8 at an update rate of 1 MHz (corresponding to a first positioning period of 1 μs) can produce vias with acceptably round openings. However, doubling the update rate to 2 MHz (corresponding to a first positioning period of 0.5 μs) distorts the process spot as scanned along the scan pattern shown in FIG. 8 to produce vias with openings having a more square-like shape. In contrast, the jump distance between successively designated spot positions in scan patterns such as those shown in FIGS. 17 to 19 can be much shorter than the jump distance between successively designated spot positions in scan patterns such as those shown in FIG. 8. For example, the jump between successively designated spot positions in the scan pattern shown in FIG. 19 can be less than 10 μm (less than three times that in the scan pattern shown in FIG. 8). As a result, when the AOD in a multi-axis AOD system is driven at an update rate of 2 MHz, and even when driven at an update rate of 8 MHz (corresponding to a first positioning period of 0.125 μs), distortion of the process spot on the workpiece 102 can be very small.

[0113] In view of the above, a second laser having a relatively large number (e.g., 40 or more) of spot positions (e.g., 45, 50, 60, 75, 80, 90, 100, 124 spot positions, etc., or any number between these values) such that consecutively designated spot positions are spatially separated from one another by up to 6 spot positions and / or such that the distance between jumps of consecutively designated spot positions is less than 15 μm (e.g., 13 μm, 11 μm, 10 μm, 9 μm, 8 μm, 7 μm, etc., or any number between these values). Vias can be formed (e.g., in the workpiece 102 described above) by operating the first positioner 106 (e.g., a multi-axis AOD system such as AOD system 200) at an update rate greater than 1 MHz (e.g., an update rate of 2 MHz, 5 MHz, 8 MHz, 12 MHz, 25 MHz, 50 MHz, etc., or any value between these values ​​or greater) to scan a process spot (e.g., having a spot size in the range described above) along a type 2 scan pattern (e.g., provided by any method described herein).

[0114] iv. Further discussion on localized heat accumulation Depending on one or more factors, such as the wavelength, pulse duration, pulse repetition rate, average power, etc. of the laser pulse irradiated on the workpiece 102, the linear absorption of the material at the spot location (e.g., relative to the wavelength of the laser pulse irradiated at the spot location), the thermal conductivity, thermal diffusivity, specific heat capacity, etc. of the material at or near the spot location, the scan pattern along which the process spot is scanned, etc., or any combination thereof, heat generated as a result of the laser pulse being irradiated at one or more spot locations may diffuse from the irradiated spot location and accumulate in areas of the workpiece 102 outside the process spot, causing an increase in the temperature of the workpiece 102 in areas outside the process spot.

[0115] The accumulated heat will increase the temperature at the area of ​​the workpiece 102 located at or near the spot location where the process spot is irradiated, and if this increase in temperature exceeds a threshold temperature (i.e., a "processing threshold temperature"), it may positively affect the efficiency with which the workpiece 102 can subsequently be processed (e.g., by direct ablation, indirect ablation, or any combination thereof). Typically, the processing threshold temperature associated with a material being processed is equal to or greater than the melting point or glass transition temperature of the material being processed, but less than its vaporization temperature. However, in other embodiments, the processing threshold temperature may be less than the melting point or glass transition temperature of the material being processed (e.g., 98%, 95%, 93%, 90%, 89%, 87%, 85%, 80%, 75%, 70%, 65%, 50%, 40%, etc., of the melting point or glass transition temperature of the material being processed, or a value between any of these values).

[0116] In some cases, the accumulated heat may increase the temperature in areas of the workpiece 102 that are not intended to be processed (each of which is also referred to herein as a "non-feature area" of the workpiece 102). If the temperature is high enough, the non-feature areas of the workpiece 102 may become undesirably damaged (e.g., undesirably scratched, melted, delaminated, annealed, etc.). Thus, it may be preferable to process the workpiece 102 to avoid undesirable heat accumulation in the non-feature areas of the workpiece 102. As used herein, the temperature at which an area of ​​the workpiece 102 may become undesirably damaged is referred to as a "damage threshold temperature." It should be understood that the damage threshold temperature of any non-feature area of ​​the workpiece 102 may depend on one or more factors, such as the thickness, thermal conductivity, thermal diffusivity, specific heat capacity, etc., absorptivity (with respect to the applied laser energy beam) of the material at or near the spot location or in the non-feature area, as well as the thermal conductivity, thermal diffusivity, specific heat capacity, size and dimensions, etc., of structures located near the non-feature area, or any combination thereof.

[0117] a. Avoid unwanted damage It has been found that the workpiece 102 may delaminate when forming the blind vias 600 in the workpiece 102 (e.g., as described above with respect to FIGS. 5 and 6) by scanning a laser energy beam (e.g., along the exemplary scan patterns described above with respect to FIGS. 8-29 or other scan patterns). Examples of areas where the workpiece 102 may delaminate include areas at the interface between the second conductor structure 504 and one or both of the dielectric structure 500 and the dielectric structure 508 at or near the peripheral area of ​​the exposed second conductor structure 504 (e.g., within the area identified by circle "A"), areas at the interface between the second conductor structure 504 and the dielectric structure 508 at or near the central area of ​​the exposed second conductor structure 504 (e.g., within the area identified by circle "B"), and any combination thereof. Applicant's experiments suggest that delamination occurs when the laser pulse irradiated on the workpiece 102 has a relatively high peak power. Towards the end of the process of forming the blind vias 600, the applied laser pulse heats the second conductive structure 504 to a substantial extent, and the heat is transferred from the second conductive structure 504 to non-feature areas (e.g., in areas such as those identified by circles "A" and / or "B") of the dielectric structure 500 and / or dielectric structure 508 adjacent to the heated second conductive structure 504. The accumulated heat can raise the temperature of the adjacent areas of the dielectric structure 500 above its glass transition temperature (and possibly above its thermal decomposition temperature), causing delamination in the workpiece 102 or making the workpiece 102 more susceptible to delamination.

[0118] To prevent delamination during the process of forming the blind vias 600, applicants have discovered that the peak power of the laser pulses applied to the workpiece 102 toward the end of the process can be lower than the peak power of the laser pulses applied earlier to the workpiece 102. It has been found that a combination of lowering the peak power of the applied laser pulses and spatially distributing the applied laser pulses (e.g., along the scan patterns exemplarily described above with respect to Figures 8-29) prevents the second conductor structure 504 from heating to any significant extent and prevents undesirable heat accumulation in adjacent regions of the dielectric structure 500 that may contribute to delamination.

[0119] For example, referring to FIG. 30, the multiple laser pulses irradiated to the workpiece 102 to form the blind via 600 may be provided as pulse slices separated in time by the first positioner 106 from a common mother laser pulse 3000. The pulse slices may be scanned along any suitable or desired scan pattern (e.g., as exemplarily described above with respect to FIGS. 8-29 or otherwise). The mother laser pulse 3000 may have a wavelength in the range of 9 μm (or thereabouts) to 11 μm (or thereabouts) (e.g., wavelengths of 9.4 μm (or thereabouts), 10.6 μm (or thereabouts), etc.) and a peak or average power in the range of 250 W (or thereabouts) to 2 kW (or thereabouts).

[0120] In this case, the pulse slice may include a first pulse slice 3002 and a second pulse slice 3004. A plurality of first pulse slices 3002 are irradiated to the workpiece 102 during a first period (e.g., this may be the total time from the start of the first slice period p1 to the end of the mth slice period pm), and then a plurality of second pulse slices 3004 are irradiated to the workpiece 102 during a second period (e.g., this may be the total time from the start of the m+1th slice period pm+1 to the end of the nth slice period pn). Although FIG. 30 illustrates only two first pulse slices 3002 (corresponding to slice periods p1 and pm), it will be understood that any number of first pulse slices 3002 may be split in time from the mother laser pulse 3000 between the first slice period p1 and the mth slice period pm. Similarly, although FIG. 30 illustrates only two second pulse slices 3004 (corresponding to slice periods pm+1 and pn), it will be appreciated that any number of second pulse slices 3004 may be separated in time from the mother laser pulse 3000 between the m+1 slice period pm+1 and the n slice period pn. The successive slice periods into which the pulse slices are separated in time from the mother laser pulse 3000 during the first period may be continuous, intermittent, or a combination thereof, as described above. Similarly, the successive slice periods into which the pulse slices are separated in time from the mother laser pulse 3000 during the second period may occur continuously, intermittently, or a combination thereof, as described above. Furthermore, although FIG. 30 illustrates the mth slice period pm and the m+1th slice period pm+1 as occurring intermittently (i.e., there is a delay after the mth slice period pm and before the m+1th slice period pm+1), it will be understood that the mth slice period pm and the m+1th slice period pm+1 may also occur continuously (i.e., the m+1th slice period pm+1 may start immediately after the mth slice period pm).

[0121] The first pulse slice 3002 may be characterized as having a substantially constant first optical power P1, and the second pulse slice 3004 may be characterized as having a substantially constant second optical power P2 that is lower than the first optical power P1. In general, as described above, the optical power of the pulse slice may be set (e.g., to the first optical power P1 or to the second optical power P2) by maintaining or varying the amplitude of the RF drive signal provided to the AOD during each slice period. In one embodiment, the first optical power P1 may be in the range of 150W (or thereabouts) to 300W (or thereabouts) (e.g., 200W or thereabouts). The second optical power P2 may be in the range of 75% to 25% (e.g., 50% or thereabouts) of the first optical power P1.

[0122] The laser pulses ultimately applied to the workpiece during the formation of the blind via 600 may have a spot size in the range of 60 μm (or thereabouts) to 90 μm (or thereabouts). However, it will be appreciated that the spot size may be smaller than 60 μm, for example, in the range of 30 μm (or thereabouts) to 60 μm (or thereabouts). Thus, the process spot scanned along the exemplary scan patterns described below may have a spot size of, for example, 40 μm (or thereabouts), 50 μm (or thereabouts), or 85 μm (or thereabouts).

[0123] In one embodiment, the first period is shorter than the second period. For example, the first period may be in the range of 4 μs (or thereabouts) to 8 μs (or thereabouts) and the second period may be in the range of 8 μs (or thereabouts) to 12 μs (or thereabouts). In other embodiments, the first period may be equal to or longer than the second period.

[0124] In one embodiment, the pulse duration of each of the first pulse slices 3002 is equal (or at least substantially equal) to the pulse duration of each of the second pulse slices 3004. For example, the first pulse slice 3002 and the second pulse slice 3004 may each have a pulse duration of 1 μs (or thereabouts). However, in other embodiments, the pulse duration of any of the first pulse slices 3002 is longer or shorter than the pulse duration of any of the second pulse slices 3004.

[0125] 30 illustrates a pulse slicing scheme that includes two pulse slice sets (i.e., a first pulse slice 3002 and a second pulse slice 3004) having different optical powers, it will be appreciated that the pulse slicing scheme described above may be modified to include one or more additional pulse slice sets, each of which may include one or more pulse slices having an optical power different from the first optical power P1 or the second optical power P2, or may have an optical power different from the optical power of the immediately preceding pulse slice set.

[0126] b. Facilitating removal of relatively thick layers It has been found that when forming vias in the workpiece 102 (e.g., as described above with respect to FIGS. 5 and 6) by scanning a laser energy beam (e.g., along the exemplary scan patterns described above with respect to FIGS. 8 to 29 or other scan patterns), if the thickness of the first conductive structure 502 is relatively thin, the via opening (formed in the first conductive material of the workpiece 102) may have a relatively low roundness when the process spot irradiated by the laser energy beam is scanned along the scan patterns described above with respect to FIGS. 8 to 22 and 24(a). For convenience of explanation, the first conductive structure 502 may be considered "relatively thin" if it has a thickness of less than 5 μm (or thereabouts). For example, the relatively thin first conductive structure 502 may have a thickness of 4.5 μm, 4 μm, 3 μm, 2.5 μm, 2 μm, 1.5 μm, 1 μm, etc., or a value between any of these values.

[0127] Indeed, as discussed above, when a process spot illuminated by a laser energy beam having a set of characteristics is scanned along a scan pattern such as those described above with respect to Figures 8-22 and 24(a) to remove a first conductive structure 502 having a thickness greater than 5 μm (e.g., greater than 5 μm, 7 μm, 9 μm, 12 μm, 18 μm, 35 μm, etc., or any value between these values), the laser energy may be distributed uniformly (or at least somewhat uniformly) over the area of ​​the workpiece 102 in which the via is to be formed before the first conductive structure 502 is ablated. However, simulations performed by applicants have shown that when the same laser energy beam (e.g., characterized by the same set of characteristics) is scanned along the same scan pattern, if the first conductive structure 502 is relatively thin (as discussed above), the first conductive structure 502 is ablated before the process spot is scanned over the entire length of the scan pattern. The results of this simulation have been confirmed by experiments performed by applicants.

[0128] A scan pattern such as any of those described above with respect to FIGS. 8-22 and 24(a) may be modified to include one or more spot locations at or near the geometric center of gravity of the scan pattern (e.g., at or near coordinates 0,0 shown in any of FIGS. 8-22 and 24(a)) to improve the circularity of the via openings formed in the relatively thin first conductive structure 502 (e.g., during the process of forming a via (e.g., blind via 600 or through via 700)). Here, the spot locations of the scan pattern actually shown in FIGS. 8-22 and 24(a) are referred to herein as "heating spot locations" and the one or more spot locations at or near the geometric center of gravity of the scan pattern are referred to herein as "removal spot locations". Heating spot locations are designated by the laser energy beam by any suitable method such as those described above with respect to FIGS. 8-22 and 24(a), and one or more removal spot locations are then designated. However, in designating the heating spot locations, the laser energy beam irradiated on the workpiece 102 is characterized by a set of properties (e.g., peak power, pulse duration, pulse energy, etc.) sufficient to uniformly (or at least somewhat uniformly) heat the region of the first conductive structure 502 where the via will be formed to a temperature at or near the processing threshold temperature of the first conductive structure 502, but insufficient to ablate the heated first conductive structure 502. One or more ablation spot locations of the modified scan pattern are then designated using a laser energy beam characterized by a set of properties (e.g., peak power, pulse duration, pulse energy, etc.) sufficient to ablate the heated region of the first conductive structure 502 (e.g., by indirect ablation, direct ablation, or a combination thereof).

[0129] In one embodiment, the peak power of the one or more pulses of the laser energy beam used to designate the ablation spot location is higher than the peak power of the one or more pulses of the laser energy beam used to designate each of the heating spot locations. It will be appreciated that the peak power of each laser pulse, whether it is designating an ablation spot location or a heating spot location, may depend on the thickness of the first conductive structure 502 (i.e., the required peak power decreases as the thickness of the first conductive structure 502 decreases). For example, for a first conductive structure 502 having a thickness of 2 μm, any ablation spot location may be designated by a laser pulse having a peak power in the range of 1 kW (or thereabouts) to 2 kW (or thereabouts), and a heating spot location may be designated by a laser pulse having a peak power in the range of 250 W (or thereabouts) to 350 W (or thereabouts). If the first conductor structure 502 has a thickness of 1.5 μm, any ablation spot location can be specified by a laser pulse having a peak power in the range of, for example, 300 W (or thereabouts) to 500 W (or thereabouts), and a heating spot location can be specified by a laser pulse having a peak power in the range of, for example, 150 W (or thereabouts) to 250 W (or thereabouts).

[0130] In other embodiments, the pulse duration of one or more pulses of the laser energy beam used to designate the removal spot location is greater than or equal to the pulse duration of each pulse used to designate the heating spot location. However, in general, the total time during which the heating spot location is designated will be greater than the total time during which the one or more removal spot locations are designated. For example, the total time during which the one or more removal spot locations are designated may range from 10% (or thereabouts) to 25% (or thereabouts) of the total time during which the heating spot locations are designated. It will be appreciated that one or more removal spot locations may be designated for more than 25% (or thereabouts) of the total time during which the heating spot locations are designated (e.g., 30% to 60% of the total time during which the heating spot locations are designated). In this case, the energy of the laser pulses applied during the removal step will also be used to remove a portion of the dielectric structure 500.

[0131] In one embodiment, by operating the first positioner 106 as described above, characteristics such as peak power and pulse duration of the laser energy beam irradiated to the workpiece 102 during heating and removal of the first conductive structure 502 can be suitably modified.

[0132] v. Further discussion on feature shape distortion As discussed above, the scan patterns illustrated in Figures 8-22 and 24(a) can be characterized as having radii ranging from 10 μm (or thereabouts) to 60 μm (or thereabouts). It will be appreciated that the radius of the scan pattern can be increased, provided that the characteristics of the scan pattern (e.g., the number of spot locations in the scan pattern, the arrangement of the spot locations in the scan pattern, the order or sequence in which the spot locations in the scan pattern are designated, the distance between successively designated spot locations, etc., or any combination thereof) and the characteristics of the laser energy beam irradiated to the workpiece 102 (e.g., average power, pulse duration, pulse repetition rate, pulse energy, peak power, spot size, etc., or any combination thereof) are maintained or modified sufficient to form a via having desired characteristics, such as the shape (e.g., circularity) of the via opening as formed in the first electrical conductor 502.

[0133] For example, when modifying a continuously specified type 2 scan pattern as shown in FIG. 17 or FIG. 19 to have a radius greater than about 60 μm (e.g., 70 μm or more), the modified continuously specified type 2 scan pattern may include, for example, more spot positions (e.g., to maintain a desired pitch between adjacent spot positions, between continuously specified spot positions, etc.). If desired, one or more characteristics (e.g., average power, pulse duration, pulse repetition rate, pulse energy, peak power, spot size, etc.) of the laser energy beam irradiated to the workpiece 102 may also be modified to form vias having desired characteristics, such as the shape (e.g., circularity) of the via opening as formed in the first conductor 502. However, it may be necessary not to simply include more spot positions (e.g., to maintain a desired pitch between adjacent spot positions, between continuously specified spot positions, etc.) when modifying a continuously specified type 2 scan pattern, since portions of the first conductor between the first and last spot positions in the scan pattern may still remain, resulting in a via opening with low circularity.

[0134] An example of a poorly rounded via opening formed in a first conductor (e.g., a copper layer) of a workpiece 102 is shown in the micrograph of FIG. 46. The via opening shown in FIG. 46 was formed by scanning a process spot (e.g., illuminated by a laser energy beam having characteristics falling within the ranges discussed above for the scan patterns shown in FIGS. 17 and 19) across the workpiece 102 along a successively designated Type 2 scan pattern similar to the scan patterns shown in FIGS. 17 and 19. Notably, however, the radius of the scan pattern was increased to 70 μm. In the micrograph shown in FIG. 46, the "tab" located within the dashed region is responsible for the poorly rounded via opening. While not wishing to be bound by a particular theory, it is believed that by the time the last spot location was designated, the temperature of the portion of the first conductor 502 at or near the first spot location of the scan pattern had fallen below the processing threshold temperature of the first conductor 502. Thus, when the final spot location was designated, there was not enough thermal energy in the first conductor 502 at or near the first spot location to facilitate its removal.

[0135] In one embodiment, the circularity of the via opening of the first conductor 502 may be improved by designating one or more of the spot positions initially designated in the scan pattern after all of the other spot positions have been designated. For example, referring to the sequentially designated type 2 scan pattern shown in FIG. 47, after the first through twenty-fourth spot positions 1-24 are designated, the position in the scan pattern designated by the first spot position 1 is designated again (thus the point indicated by "1,25" represents the positions of the first spot position and the twenty-fifth spot position in the scan pattern). If necessary, other previously designated spot positions may be designated after the twenty-fifth spot position. For example, referring again to FIG. 47, spot position 2 is designated after designating spot position 25 (thus the point indicated by "2,26" represents the positions of the second spot position and the twenty-sixth spot position, which overlap with each other). Spot position 3 may be designated after designating spot position 26 (thus the point indicated by "3,27" represents the positions of the third spot position and the twenty-seventh spot position, which overlap with each other). As used herein, spot positions that overlap one another (e.g., as described above) are referred to herein as "successively designated type 2 scan pattern overlap spot positions." For any successively designated type 2 scan pattern overlap spot positions, the spot position that is last designated is referred to as the "last designated overlap spot position." Thus, in the spot positions designated by "1,25," spot position 25 can be referred to as the "last designated overlap spot position," in the spot positions designated by "2,26," spot position 26 can be referred to as the "last designated overlap spot position," and so on.

[0136] In terms of maintaining a desired circularity of the via opening in the first conductor, a suitable continuously designated type 2 scan pattern provides a first 1 spot position as a continuously designated type 2 scan pattern overlap spot position. One or more continuously designated spot positions following the 1 spot position may also be provided as a continuously designated type 2 scan pattern overlap spot position. Thus, the number of continuously designated type 2 scan pattern overlap spot positions that may be included in a type 2 scan pattern may be equal to 1, 2, 3, 4, 5, etc. Instead of specifying the number of continuously designated type 2 scan pattern overlap spot positions that may be included in a type 2 scan pattern, the number of continuously designated type 2 scan pattern overlap spot positions that may be included in a type 2 scan pattern may be expressed as a percentage of the total number of spot positions in the type 2 scan pattern. In this case, the continuously designated type 2 scan pattern overlap spot positions may occupy 12% (or thereabouts) of the total number of spot positions in the type 2 scan pattern. For example, this percentage can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, etc., or a value between any of these values. Ultimately, however, the number of consecutively designated Type 2 scan pattern overlap spot positions included within a Type 2 scan pattern may depend on one or more factors, such as any of the scan pattern characteristics discussed above, any of the characteristics of the laser energy beam irradiated to the workpiece 102 (e.g., wavelength, average power, pulse duration, pulse repetition rate, pulse energy, peak power, light intensity, fluence, spot size, etc.), characteristics of the workpiece 102 (e.g., thickness of the first conductor, etc.), or the like, or any combination thereof. By providing a continuously specified type 2 scan pattern as described above with respect to FIG. 47, a region of the first conductor at or near the first spot location (i.e., spot location 1) can accumulate sufficient thermal energy to facilitate its removal, thereby producing a highly circular via opening in the first conductor (e.g., as shown in FIG. 48).It should be noted that if too many spot positions are provided as consecutively designated type 2 scan pattern overlapping spot positions, the first conductor may be over-processed, again resulting in a poorly rounded via opening in the first conductor as shown in FIG. 49.

[0137] So far, the distance between each pair of consecutively designated spot positions in a consecutively designated type 2 scan pattern, such as any of those described with respect to Figs. 17 and 19, is the same (or at least approximately the same). For example, the distance between spot positions 3 and 4 in either Fig. 17 or Fig. 19 is the same (or approximately the same) as the distance between spot position 1 and the last spot position (i.e., spot position 12 in Fig. 17 and spot position 18 in Fig. 19). In terms of maintaining a desired circularity of the via opening in the first conductor, a suitable consecutively designated type 2 scan pattern can be configured such that the distance between the pair of consecutively designated spot positions, including the last spot position designated, can be shorter than the distances that separate the remaining pairs of consecutively designated spot positions. For example, referring to Fig. 50, the distance between spot positions 24 and 25 can be shorter than the distance between spot positions 1 and 2, between spot positions 10 and 11, etc. In general, the distance between the last two assigned spot locations (e.g., between spot locations 24 and 25) may range between 30% (or thereabouts) and 99% (or thereabouts) of the distance between other pairs of successively assigned spot locations. By providing a successively assigned type 2 scan pattern as described above with respect to FIG. 50, a region of the first conductor at or near the initial spot location (i.e., spot location 1) may accumulate sufficient thermal energy to facilitate its removal, thereby producing a highly circular via opening in the first conductor.

[0138] In other embodiments, the continuously designated type 2 scan pattern can be modified to include one or more spot positions between at least one pair of continuously designated spot positions. Thus, the continuously designated spot positions in one portion of the type 2 scan pattern may be adjacent to each other (e.g., similar to a continuously designated type 2 scan pattern) and the continuously designated spot positions in another portion of the type 2 scan pattern may not be adjacent to each other (e.g., similar to a non-continuously designated type 2 scan pattern). This type of type 2 scan pattern is referred to herein as a "hybrid type 2 scan pattern." An example of a hybrid type 2 scan pattern is shown in FIG. 51. Referring to FIG. 51, the hybrid type 2 scan pattern may include a distance between spot positions 24 and 25 (designated continuously after spot position 24) with spot position 25 located between spot positions 1 and 2. Although FIG. 51 illustrates only one spot location (i.e., spot location 25) located between spot locations 1 and 2, it will be appreciated that multiple spot locations may be located between spot locations 1 and 2 or between any other pair of consecutively designated spot locations. If desired, the hybrid type 2 scan pattern may further include one or more additional spot locations, such as spot location 26 (consecutively designated after spot location 25), located between one or more additional pairs of consecutively designated spot locations, such as between spot locations 2 and 3. By providing a hybrid type 2 scan pattern as described above with respect to FIG. 51, a region of the first conductor at or near the initial spot location (i.e., spot location 1) may accumulate sufficient thermal energy to facilitate its removal, thereby creating a highly circular via opening in the first conductor (e.g., as shown in FIG. 48).Ultimately, however, the number of spot locations added between a pair of consecutively designated spot locations or the number of pairs of consecutively designated spot locations between which spot locations are located may depend on one or more factors, such as any of the scan pattern characteristics described above, any of the characteristics of the laser energy beam irradiated on the workpiece 102 (e.g., wavelength, average power, pulse duration, pulse repetition rate, pulse energy, peak power, light intensity, fluence, spot size, etc.), characteristics of the workpiece 102 (e.g., thickness of the first conductor, etc.), or any combination thereof. It should be noted that if too many spot locations are provided between a pair of consecutively designated spot locations or if too many pairs of consecutively designated spot locations have one or more spot locations between them, the first conductor may be over-machined and a poorly rounded via opening may be produced in the first conductor (e.g., as shown in FIG. 49 ).

[0139] Although type 2 scan patterns useful for generating vias having relatively large radii and highly circular openings have been described separately above with respect to Figures 47, 50 and 51, it should be appreciated that the characteristics inherent to each type of type 2 scan pattern may be combined in any suitable or desired manner.

[0140] B. Feature formation by punch process To form a feature such as a via (e.g., a blind via 600 as illustratively shown in FIG. 6 or a through via 700 as illustratively shown in FIG. 7) in a workpiece 102 (e.g., configured as described above), the first positioner 106 may be provided as a multi-axis AOD system (e.g., AOD system 200) and operated to repeatedly generate process spots at the same (or substantially the same) location in the workpiece 102. As used herein, the term "punch process" refers to applying a set of laser pulses to the same (or substantially the same) spot location in the workpiece 102 to form a feature (e.g., a via or other aperture). During the punch process (e.g., to form a feature such as a via or other aperture), the first positioner 106 may be operated to perform full pulse deflection or partial pulse deflection (i.e., pulse slicing as described above) or a combination of full pulse deflection and partial pulse deflection.

[0141] During a punching process (e.g., to form a feature such as a via or other opening), the first positioner 106 can be operated to prevent excessive heating (as a result of the application of laser pulses) of the material of the workpiece 102 (e.g., the dielectric structure 500) or to prevent the workpiece 102 (or one or more component structures of the workpiece 102) from undesirably warping, delaminating, or modifying. As described in more detail below, during a punching process, the first positioner 106 can be operated to ensure that the laser pulses in at least one consecutive pair of laser pulses in the set are intermittent (i.e., one laser pulse begins following an immediate delay after the previous laser pulse), modify the optical power of one laser pulse in the set relative to the other laser pulses, modify the pulse duration of one laser pulse in the set relative to the other laser pulses, or any combination thereof.

[0142] i. Example of Pulse Slicing Embodiments Referring to FIG. 32, the first positioner 106 can be operated to split a mother laser pulse (e.g., mother laser pulse 3201) into multiple pulse slices in time during the punching process. To this end, the first positioner 106 can be operated to deflect the pulse slices by the same angle (or at least substantially the same angle) within the primary angle range 116 in at least one consecutively split pulse slice pair. It will be appreciated that the multiple pulse slices themselves can be grouped into multiple pulse slice sets (e.g., pulse slice sets 3200a and 3200b, each of which is collectively referred to as "pulse slice sets 3200"). In this case, the first positioner 106 can be operated to deflect the pulse slices in a common pulse slice set 3200 by the same angle (or at least substantially the same angle) within the primary angle range 116, and to deflect the pulse slices in different pulse slice sets 3200 by different angles (or at least substantially different angles) within the primary angle range 116. For example, the first positioner 106 may be operated to deflect the pulse slices in the pulse slice set 3200a by a first angle in the primary angle range 116 shown in FIG. 1 (or by an angle in the first primary angle range 116a shown in FIG. 31) and to deflect the pulse slices in the pulse slice set 3200b by a second angle in the primary angle range 116 shown in FIG. 1 (or by an angle in the second primary angle range 116b shown in FIG. 31). However, it will be understood that the pulse slices in the pulse slice sets 3200a and 3200b may be considered as a common pulse slice set, and thus all of the pulse slice sets 3200a and 3200b of pulse slices may be deflected to the same (or at least substantially the same) angle in the primary angle range 116. As illustratively shown, at a given time, the power of a pulse slice is lower than the power of the mother laser pulse 3201 from which the pulse slice is time-divided.The difference in power between the mother laser pulse 3201 and the pulse slice may be the result of the diffraction efficiency of one or more AODs in the first positioner 106 when the first positioner 106 is operated to generate the pulse slice, inherent optical losses associated with the use of AODs in the first positioner 106, etc., or any combination of these.

[0143] In the illustrated embodiment, the pulse slice set 3200a includes a primary pulse slice 3202a and a plurality of secondary pulse slices 3204a. Similarly, in the illustrated embodiment, the pulse slice set 3200b includes a primary pulse slice 3202b and a plurality of secondary pulse slices 3204b. As used herein, each of the primary pulse slices 3202a and 3202b is collectively referred to as a "primary pulse slice 3202," and each of the secondary pulse slices 3204a and 3204b is collectively referred to as a "secondary pulse slice 3204." In the illustrated embodiment, the pulse duration and pulse energy of the primary pulse slice 3202 is greater than the pulse duration and pulse energy of each of the secondary pulse slices 3204. However, the pulse slice set 3200a may include a plurality of primary pulse slices 3202a and one or more secondary pulse slices 3204a. Similarly, in other embodiments, the pulse slice set 3200b can include a plurality of primary pulse slices 3202b and one or more secondary pulse slices 3204b.

[0144] In one embodiment, the primary pulse slice 3202 is used to ablate (via direct ablation, indirect ablation, or a combination thereof) the first conductive structure 502 of the workpiece 102. In this case, the pulse duration and pulse energy of a single primary pulse slice 3202 are sufficient to ablate the first conductive structure 502 of the workpiece 102. In another case, the pulse duration and pulse energy of each of the multiple primary pulse slices 3202 in the common pulse slice set 3200 are sufficient to ablate the first conductive structure 502 by the multiple primary pulse slices 3202. However, in other embodiments, one or more primary pulse slices 3202 can be used to ablate (via direct ablation, indirect ablation, or a combination thereof) the dielectric structure 500 of the workpiece 102 when the first conductive structure 502 is not present at the desired spot location on the workpiece 102. It should be noted that the pulse duration, pulse energy, peak optical power, and temporal optical power profile (e.g., rectangular as shown by the various pulse slices in FIG. 32) of at least one primary pulse slice 3202 in a pulse slice set may be greater than, less than, or the same as the pulse duration, pulse energy, peak optical power, and temporal optical power profile (e.g., rectangular as shown by the various pulse slices in FIG. 32) of other primary pulse slices 3202 in the same pulse slice set.

[0145] In one embodiment, each secondary pulse slice 3204 is generally used to remove the dielectric structure 500 of the workpiece 102 without significantly modifying the second conductive structure 504 (e.g., to form a blind via such as blind via 600). In this case, the pulse duration and pulse energy of each secondary pulse slice 3204 is sufficient to remove the first conductive structure 502 of the workpiece 102 (e.g., via ablation, evaporation, melting, etc., or any combination thereof), and the pulse duration and / or pulse energy of at least the last secondary pulse slice 3204 is sufficient to remove the dielectric structure 500 of the workpiece 102 without significantly modifying the second conductive structure 504. Thus, the pulse duration, pulse energy, peak optical power, and temporal optical power profile (e.g., rectangular as shown by the various pulse slices in FIG. 32) of at least one secondary pulse slice 3204 in a pulse slice set may be greater than, less than, or the same as the pulse duration, pulse energy, peak optical power, and temporal optical power profile (e.g., rectangular as shown by the various pulse slices in FIG. 32) of other secondary pulse slices 3204 in the same pulse slice set.

[0146] In other embodiments, one or more secondary pulse slices 3204 can be used to ablate (via direct ablation, indirect ablation, or a combination thereof) the second conductive structure 504 of the workpiece 102. In this case, one or more secondary pulse slices 3204 applied to the workpiece 102 after the second conductive structure 504 has been ablated can be used to remove (e.g., via ablation, evaporation, melting, etc., or any combination thereof) the dielectric structure 508 (e.g., to form a through via such as through via 700). Thus, the pulse duration, pulse energy, peak optical power, and temporal optical power profile (e.g., rectangular as shown by the various pulse slices in FIG. 32) of at least one secondary pulse slice 3204 in a pulse slice set may be greater than, less than, or the same as the pulse duration, pulse energy, peak optical power, and temporal optical power profile (e.g., rectangular as shown by the various pulse slices in FIG. 32) of other secondary pulse slices 3204 in the same pulse slice set.

[0147] However, in yet other embodiments, pulse slice sets 3200a and 3200b can be used to form through vias (e.g., through via 700). In this case, pulse slice set 3200a can be used to sequentially remove material from first conductive structure 502 and dielectric structure 500, and pulse slice set 3200b can be used to sequentially remove material from second conductive structure 504 and dielectric structure 508.

[0148] In yet another embodiment, if the dielectric structure 500 is a non-homogeneous material (e.g., FR4, known as fiberglass reinforced epoxy laminate, which includes woven fiberglass in an epoxy resin matrix), and if a portion of the dielectric structure 500 at the desired spot location of the workpiece 102 includes glass material, the pulse duration and pulse energy of at least one secondary pulse slice 3204 intended to remove the glass material can be modified relative to the pulse duration and pulse energy of at least one other secondary pulse slice 3204 intended only to remove the epoxy resin, so as to efficiently remove (e.g., via ablation, evaporation, melting, etc., or any combination thereof) the glass material at the desired spot location. Thus, the pulse duration, pulse energy, peak optical power, and temporal optical power profile (e.g., rectangular as shown by the various pulse slices in FIG. 32) of at least one secondary pulse slice 3204 in a pulse slice set may be greater than, less than, or the same as the pulse duration, pulse energy, peak optical power, and temporal optical power profile (e.g., rectangular as shown by the various pulse slices in FIG. 32) of other secondary pulse slices 3204 in the same pulse slice set.

[0149] When successive laser pulses are applied intermittently during the punch process, the first positioner 106 can be operated to ensure that the time between the start of one laser pulse and the end of the previous laser pulse (also referred to herein as the "gap time") is sufficient to allow some cooling of the material at or near the spot location (e.g., below the material's damage threshold temperature) before the next laser pulse is applied. For example, referring to FIG. 32, the first positioner 106 can be operated to ensure that the gap time Tg1a between the start of the first secondary pulse slice 3204a of the pulse slice set 3200a and the end of the primary pulse slice 3202a of the pulse slice set 3200a is sufficient to allow some cooling of the material of the dielectric structure 500 at or near the spot location before the first secondary pulse slice 3204a is applied, thereby avoiding undesired modification of the material of the dielectric structure 500 at or near the spot location. The gap time Tg1b between the start of the first secondary pulse slice 3204b of the pulse slice set 3200b and the end of the first primary pulse slice 3202b of the pulse slice set 3200b may be longer than, shorter than, or equal to the gap time Tg1a.

[0150] 32, the first positioner 106 can be operated to ensure that the gap time Tg2 between successively applied secondary pulse slices 3204a of the pulse slice set 3200a is sufficient to maintain the material of the dielectric structure 500 at or near the spot location at a temperature sufficient to enable suitable processing of the dielectric structure 500 without undesirably damaging the surrounding material. The gap time between successively applied secondary pulse slices 3204b of the pulse slice set 3200b can be longer, shorter, or equal to the gap time Tg2.

[0151] a. Sequential and interleaved deflection of sets of laser pulses Referring to FIG. 32, the first positioner 106 can be operated to split the mother laser pulse 3201 into multiple pulse slice sets 3200 in time during the punching process. The pulse slices in the laser pulse slice set 3200a are all deflected to the same (or at least substantially the same) angle within the primary angle range 116 before the pulse slices in the laser pulse slice set 3200b are deflected to a different angle. In this manner, the first positioner 106 is operated to deflect the laser pulse slice sets 3200a and 3200b by a sequential deflection method. In another embodiment, the first positioner 106 can be operated to deflect the laser pulse slice sets 3200a and 3200b by an interleaved deflection method. In the interleaved deflection method, during the punch process, the first positioner 106 is operated to temporally divide the mother laser pulse 3201 into multiple pulse slice sets 3200, and one or more pulse slices in the laser pulse slice sets 3200a and 3200b are deflected alternately between different angles within the primary angle range 116.

[0152] For example, referring to FIG. 33, a primary pulse slice 3202a may be deflected by a first angle within the primary angle range 116 shown in FIG. 1 (or by a first angle within the first primary angle range 116a shown in FIG. 31), then a primary pulse slice 3202b may be deflected by a second angle within the primary angle range 116 shown in FIG. 1 (or by a first angle within the second primary angle range 116b shown in FIG. 31), then a secondary pulse slice 3202b may be deflected by a second angle within the primary angle range 116 shown in FIG. 1 (or by a first angle within the second primary angle range 116b shown in FIG. 31), and then a secondary pulse slice 3202c may be deflected by a second angle within the primary angle range 116 shown in FIG. The first positioner 106 can be operated using an interleaved deflection method in which the secondary pulse slice 3204a is deflected by a first angle within the primary angle range 116 shown in FIG. 1 (or by a first angle within the first primary angle range 116a shown in FIG. 31), and then the secondary pulse slice 3204b is deflected by a second angle within the primary angle range 116 shown in FIG. 1 (or by a first angle within the second primary angle range 116b shown in FIG. 31).

[0153] In another example, referring to FIG. 34, similar to the method described with respect to FIG. 33, the first positioner 106 can be operated using an interleaved deflection method in which the secondary pulse slices 3204a and 3204b are alternately deflected between a first angle and a second angle within the primary angle range 116 shown in FIG. 1 (or between a first angle in the first primary angle range 116a and the second primary angle range 116b shown in FIG. 31).

[0154] Considering the above-mentioned gap time between pulse slices in a pulse slice set, the total time required to form a feature (e.g., a via or other opening) by a punch process may vary whether the first positioner 106 is operated by a sequential deflection method or an interleaved deflection method. For example, if the total time required to form a feature using the pulse slice set 3200a is Ta and the total time required to form a feature using the pulse slice set 3200b is Tb (Tb may be longer, shorter, or equal to Ta), then the total time required to form two features using the pulse slice sets 3200a and 3200b is Tt1 when the first positioner 106 is operated by a sequential deflection method (see, for example, FIG. 32). However, the total time required to form the same two features using the pulse slice sets 3200a and 3200b using the interleaved deflection method shown in FIG. 33 is Tt2, which is shorter than Tt1. It should be noted that while gap time Tg1b' is shown in FIG. 33 as being longer than gap time Tg1b, it may be made equal to gap time Tg1b by adjusting the pulse duration and / or power of secondary pulse slice 3204a, by adjusting the gap time between the first primary pulse slice 3202b and the first secondary pulse slice 3204a, by adjusting the gap time Tg2 between secondary pulse slices 3204a, by adjusting the gap time between the last secondary pulse slice 3204a and the first secondary pulse slice 3204b, etc., or by any combination of these.

[0155] Similarly, using the interleaved deflection method shown in FIG. 34, the total time required to form two features using pulse slice sets 3200a and 3200b is Tt2. Note that although gap time Tg1b″ is shown in FIG. 34 as being shorter than gap time Tg1b, it may be made equal to gap time Tg1b by, for example, adjusting the pulse duration and / or power of the first secondary pulse slice 3204a, by adjusting the gap time between the primary pulse slice 3202b and the first secondary pulse slice 3204a, by adjusting the gap time Tg2 between the secondary pulse slices 3204a, etc., or any combination thereof.

[0156] Although embodiments have been described herein with respect to punch processes, it will be understood that these embodiments may also be applied to form features using a scan pattern (e.g., by scanning a process spot along a scan pattern as illustratively described herein with respect to Figures 8 to 29, 47, 50 or 51, or otherwise).

[0157] b. Additional examples of laser pulse sets 32-34, each pulse slice in the pulse slice set has a rectangular temporal power profile, and the peak optical power of any pulse slice in the pulse slice set is the same as the peak optical power of all other pulse slices in the pulse slice set. In other embodiments, one or more pulse slices in the pulse slice set may have a temporal power profile of another shape, the peak optical power of any pulse slice in the pulse slice set may be different from the other pulse slices in the pulse slice set, or a combination thereof.

[0158] Furthermore, in the examples shown in FIG. 32 to FIG. 34, between different pulse slice sets, the characteristics of the pulse slices in one pulse slice set (i.e., pulse energy, pulse duration, temporal power profile, number of pulse slices, gap time, etc.) are the same (or substantially the same) as the characteristics of the corresponding pulse slices in another pulse slice set. Therefore, the pulse slice sets separated in time from the common mother pulse can be considered to be the same. In another embodiment, at least one characteristic (e.g., pulse energy, pulse duration, temporal power profile, number of pulse slices, gap time, etc.) of at least one pulse slice in one pulse slice is different from the characteristics of at least one corresponding pulse slice in another pulse slice set. Therefore, the pulse slice sets separated in time from the common mother pulse can be considered to be different.

[0159] 35-45 illustrate further embodiments of exemplary pulse slice sets that may be generated by operating the first positioner 106 during a punch process or during a process spot scanning process (e.g., by scanning the process spot along any of the above-mentioned scan patterns described herein, or by other methods) to form a feature (e.g., a via or other opening, such as a blind via or a through via).

[0160] 42, the temporal power profile of the secondary pulse slice 3204 is continuously modulated (e.g., as indicated by the downward sloping lines). In this case, the secondary pulse slice 3204 shown in FIG. 42 may be deflected by a single angle within the primary angle range 116, or may be deflected (over time) by multiple angles within a common primary angle range 116. In FIG. 42, reference numeral 3204' denotes another secondary pulse slice relative to another secondary pulse slice 3204 whose temporal power profile is continuously modulated (e.g., increasing rather than decreasing over time). FIGS. 44 and 45 show another embodiment in which the secondary pulse slice 3204 may have different continuously modulated temporal power profiles.

[0161] 43, the temporal power profile of the secondary pulse slice 3204 is modulated in a stepped manner. In this case, the secondary pulse slice 3204 shown in FIG. 43 may be deflected by a single angle within the primary angle range 116, or may be deflected (over time) by multiple angles within a common primary angle range 116. Similar to the example shown in FIG. 42, the secondary pulse slice 3204 shown in FIG. 43 may be inverted (e.g., so that the secondary pulse slice 3204 has a relatively low optical power before being modulated to have a relatively high optical power).

[0162] IX. Conclusion The above is a description of the embodiments and examples of the present invention, and should not be construed as being limiting thereto. Although some specific embodiments and examples have been described with reference to the drawings, those skilled in the art will readily recognize that many modifications to the disclosed embodiments and examples and other embodiments are possible without significantly departing from the novel teachings and advantages of the present invention. Accordingly, all such modifications are intended to be included within the scope of the present invention as defined in the claims. For example, those skilled in the art will understand that the subject matter of any sentence, paragraph, example, or embodiment can be combined with any or all of the subject matter of any other sentence, paragraph, example, or embodiment, unless such combinations are mutually exclusive. Thus, the scope of the present invention should be determined by the following claims and the equivalents of such claims to be included therein.

Claims

1. 1. A method of forming a feature in a workpiece including a first structure and a second structure, the feature including an opening formed in the first structure; scanning the laser energy beam onto the workpiece such that the laser energy beam is incident on the first structure to sequentially irradiate a plurality of spatially distinct spots of the laser energy in a scan pattern, the scanning including: a) applying the laser energy to at least two of the plurality of spatially distinct spot locations to distribute the laser energy within an area of ​​the workpiece where the feature is to be formed; b) after a), irradiating at least two of the plurality of spatially distinct spot locations with the laser energy to indirectly ablate the first structure within the region, thereby forming the opening. method.

2. The method of claim 1 , wherein the first structure is a conductive structure and the second structure is a dielectric structure.

3. The method of claim 2 , wherein the first structure has a thickness in the range of 1 μm to 20 μm.

4. The method of claim 1 , wherein the laser energy has a wavelength in the infrared region of the electromagnetic spectrum.

5. The method of claim 1 , wherein the laser energy has a wavelength in the ultraviolet region of the electromagnetic spectrum.

6. The method of claim 1 , further comprising: scanning the beam of laser energy to deliver the laser energy to each of the plurality of spot locations, the beam of laser energy delivering at least one laser pulse to each of the plurality of spot locations.

7. 7. The method of claim 6, further comprising: scanning said beam of laser energy to deliver said laser energy to at least one of said plurality of spot locations with only one laser pulse.

8. while scanning the laser energy beam to irradiate the laser energy, generating a first laser pulse with a laser source; splitting the first laser pulse in time into a plurality of second laser pulses; 2. The method of claim 1.

9. The method of claim 8 , wherein at least two of the plurality of second laser pulses have different pulse durations.

10. The method of claim 8 , wherein at least two of the plurality of second laser pulses have the same pulse duration.

11. The method of claim 8 , wherein at least one of the plurality of second laser pulses has a pulse duration of 1 μs or less.

12. 12. The method of claim 11, wherein at least one of the plurality of second laser pulses has a pulse duration of 0.5 μs or less.

13. 13. The method of claim 12, wherein at least one of the plurality of second laser pulses has a pulse duration of 0.25 μs or less.

14. 14. The method of claim 13, wherein at least one of the plurality of second laser pulses has a pulse duration of 0.125 μs or less.

15. 15. The method of claim 11, wherein at least one of the second laser pulses has a pulse duration of 0.125 μs or less.

16. The method of claim 8 , wherein at least two of the plurality of second laser pulses have different peak powers.

17. The method of claim 8 , wherein at least two of the plurality of second laser pulses have the same peak power.

18. The method of claim 8 , further comprising: diffracting the first laser pulse when the first laser pulse is split in time.

19. 2. The method of claim 1 , wherein the scan pattern includes at least three spot locations, and when scanning the laser energy beam such that the laser energy is irradiated at the plurality of spatially distinct spot locations of the scan pattern, the laser energy is irradiated at a first spot location of the scan pattern, and thereafter the laser energy is irradiated at a second spot location of the scan pattern, and a first distance between a center of the first spot location and a center of the second spot location of the scan pattern is greater than a second distance between a center of the first spot location and a center of a third spot location of the scan pattern.

20. 2. The method of claim 1 , wherein the scan pattern includes at least three spot locations, and when scanning the laser energy beam such that the laser energy is irradiated at the plurality of spatially distinct spot locations of the scan pattern, the laser energy is irradiated at a first spot location of the scan pattern, then at a second spot location of the scan pattern, and then at a third spot location of the scan pattern, and a first distance between a center of the first spot location and a center of the second spot location of the scan pattern is less than a second distance between a center of the first spot location and a center of a third spot location of the scan pattern.

21. 21. The method of claim 19 or 20, wherein the first distance is less than 15 μm.

22. 22. The method of claim 21, wherein the first distance is less than 10 μm.

23. 2. The method of claim 1, wherein the laser energy is applied to different spot locations at a rate of 20 kHz or greater as the laser energy sequentially applies to the plurality of spatially distinct spots of the scan pattern.

24. 24. The method of claim 23, wherein the rate is greater than or equal to 1 MHz.

25. 25. The method of claim 24, wherein the rate is greater than or equal to 2 MHz.

26. 26. The method of claim 25, wherein the rate is 5 MHz or greater.

27. 27. The method of claim 26, wherein the rate is greater than or equal to 8 MHz.

28. the first structure is made of metal; a portion of the first structure melts as the first structure is indirectly ablated to form the opening; 2. The method of claim 1.

29. 30. The method of claim 28, wherein a portion of the first structure is not melted when the first structure is indirectly ablated to form the opening, and the unmelted portion is surrounded by a melted portion.

30. 1. An apparatus for forming a feature in a workpiece including a first structure and a second structure, the feature including an opening formed in the first structure; a laser source capable of generating a beam of laser energy propagable along a beam path incident on the first structure of the workpiece; a positioner capable of deflecting the beam path; a controller communicatively coupled to the positioner; the controller is configured to control operation of the positioner to perform a scanning process in which the beam path is deflected along a scan pattern to sequentially irradiate the laser energy at a plurality of spatially distinct spot locations of the scan pattern, and during the scanning process: a) the laser energy is capable of being applied to at least two of the plurality of spatially distinct spot locations to distribute the laser energy within an area of ​​the workpiece where the feature is to be formed; b) after a), the laser energy can be applied to at least two of the plurality of spatially distinct spot locations to indirectly ablate the first structure in the region, thereby forming the opening; Device.

31. a laser source capable of generating a laser energy beam having at least one laser pulse, the laser energy beam capable of propagating along a beam path to a workpiece; an acousto-optic deflector (AOD) system capable of deflecting the beam path, the AOD system including a first AOD capable of deflecting the beam path along a first axis in response to an applied first RF signal; a controller communicatively coupled to the AOD system and configured to control operation of the AOD system whereby a frequency of the first RF signal is varied at least twice to split in time a common laser pulse incident on the AOD system into a plurality of pulse slices, the frequency of the first RF signal being varied at a rate of 20 kHz or greater; Equipped with Device.

32. 32. The apparatus of claim 31, wherein the frequency of the first RF signal is varied at a rate of 1 MHz or greater.

33. 33. The apparatus of claim 32, wherein the rate is greater than or equal to 2 MHz.

34. 34. The apparatus of claim 33, wherein the rate is 5 MHz or greater.

35. 35. The apparatus of claim 34, wherein the rate is greater than or equal to 8 MHz.

36. 32. The apparatus of claim 31 , wherein the AOD system further includes a second AOD capable of deflecting the beam path along a second axis in response to an applied second RF signal.

37. 37. The apparatus of claim 36, wherein the controller is further configured to control operation of the AOD system to deflect the beam path, thereby changing the frequency of the first RF signal and the second RF signal each time a pulse slice is separated in time from the common laser pulse.

38. a laser source capable of generating a laser energy beam having at least one laser pulse, the laser energy beam capable of propagating along a beam path to a workpiece; a first scan head including a scan lens; a second scan head including a scan lens; a positioner capable of selectively deflecting the beam path between the first scan head and the second scan head; a controller communicatively coupled to the positioner; the controller is configured to control operation of the positioner to temporally split a common laser pulse incident on the positioner into a plurality of pulse slices including a first set of pulse slices and a second set of pulse slices, the controller further comprising: deflecting the first pulse slice set to the first scan head; deflecting the second set of pulse slices to the second scan head; and wherein at least one pulse slice in the second pulse slice set is located between two consecutive pulse slices in the first pulse slice set in time. Device.

39. 39. The apparatus of claim 38, wherein the at least one pulse slice in the second pulse slice set is located in time between a first pulse slice of the plurality of pulse slices in the first pulse slice set and a second pulse slice of the plurality of pulse slices in the first pulse slice set.

40. 40. The apparatus of claim 39, wherein the positioner includes an acousto-optic deflector (AOD), and the controller is configured to control the AOD to modulate a power of the common laser pulse such that a pulse energy of a pulse slice that is first in time among the plurality of pulse slices in the first pulse slice set is greater than a pulse energy of a pulse slice that is second in time among the plurality of pulse slices in the first pulse slice set.

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